Merge tag 'trace-v4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "New features:

   - Tom Zanussi's extended histogram work.

     This adds the synthetic events to have histograms from multiple
     event data Adds triggers "onmatch" and "onmax" to call the
     synthetic events Several updates to the histogram code from this

   - Allow way to nest ring buffer calls in the same context

   - Allow absolute time stamps in ring buffer

   - Rewrite of filter code parsing based on Al Viro's suggestions

   - Setting of trace_clock to global if TSC is unstable (on boot)

   - Better OOM handling when allocating large ring buffers

   - Added initcall tracepoints (consolidated initcall_debug code with
     them)

  And other various fixes and clean ups"

* tag 'trace-v4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (68 commits)
  init: Have initcall_debug still work without CONFIG_TRACEPOINTS
  init, tracing: Have printk come through the trace events for initcall_debug
  init, tracing: instrument security and console initcall trace events
  init, tracing: Add initcall trace events
  tracing: Add rcu dereference annotation for test func that touches filter->prog
  tracing: Add rcu dereference annotation for filter->prog
  tracing: Fixup logic inversion on setting trace_global_clock defaults
  tracing: Hide global trace clock from lockdep
  ring-buffer: Add set/clear_current_oom_origin() during allocations
  ring-buffer: Check if memory is available before allocation
  lockdep: Add print_irqtrace_events() to __warn
  vsprintf: Do not preprocess non-dereferenced pointers for bprintf (%px and %pK)
  tracing: Uninitialized variable in create_tracing_map_fields()
  tracing: Make sure variable string fields are NULL-terminated
  tracing: Add action comparisons when testing matching hist triggers
  tracing: Don't add flag strings when displaying variable references
  tracing: Fix display of hist trigger expressions containing timestamps
  ftrace: Drop a VLA in module_exists()
  tracing: Mention trace_clock=global when warning about unstable clocks
  tracing: Default to using trace_global_clock if sched_clock is unstable
  ...

13 files changed, 5828 insertions, 1692 deletions

diff --git a/kernel/panic.c b/kernel/panic.c
index 9d833d913c84..6c3b08cd1139 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -554,6 +554,8 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 	else
 		dump_stack();
 
+	print_irqtrace_events(current);
+
 	print_oops_end_marker();
 
 	/* Just a warning, don't kill lockdep. */
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 704e55129c3a..2f4af216bd6e 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -51,6 +51,7 @@
 #include <linux/uaccess.h>
 #include <asm/sections.h>
 
+#include <trace/events/initcall.h>
 #define CREATE_TRACE_POINTS
 #include <trace/events/printk.h>
 
@@ -2780,6 +2781,7 @@ EXPORT_SYMBOL(unregister_console);
  */
 void __init console_init(void)
 {
+	int ret;
 	initcall_t *call;
 
 	/* Setup the default TTY line discipline. */
@@ -2790,8 +2792,11 @@ void __init console_init(void)
 	 * inform about problems etc..
 	 */
 	call = __con_initcall_start;
+	trace_initcall_level("console");
 	while (call < __con_initcall_end) {
-		(*call)();
+		trace_initcall_start((*call));
+		ret = (*call)();
+		trace_initcall_finish((*call), ret);
 		call++;
 	}
 }
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 0b249e2f0c3c..c4f0f2e4126e 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -606,7 +606,10 @@ config HIST_TRIGGERS
 	  event activity as an initial guide for further investigation
 	  using more advanced tools.
 
-	  See Documentation/trace/events.txt.
+	  Inter-event tracing of quantities such as latencies is also
+	  supported using hist triggers under this option.
+
+	  See Documentation/trace/histogram.txt.
 	  If in doubt, say N.
 
 config MMIOTRACE_TEST
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index eac9ce2c57a2..16bbf062018f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3902,14 +3902,13 @@ static bool module_exists(const char *module)
 {
 	/* All modules have the symbol __this_module */
 	const char this_mod[] = "__this_module";
-	const int modname_size = MAX_PARAM_PREFIX_LEN + sizeof(this_mod) + 1;
-	char modname[modname_size + 1];
+	char modname[MAX_PARAM_PREFIX_LEN + sizeof(this_mod) + 2];
 	unsigned long val;
 	int n;
 
-	n = snprintf(modname, modname_size + 1, "%s:%s", module, this_mod);
+	n = snprintf(modname, sizeof(modname), "%s:%s", module, this_mod);
 
-	if (n > modname_size)
+	if (n > sizeof(modname) - 1)
 		return false;
 
 	val = module_kallsyms_lookup_name(modname);
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index dcf1c4dd3efe..c9cb9767d49b 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -22,6 +22,7 @@
 #include <linux/hash.h>
 #include <linux/list.h>
 #include <linux/cpu.h>
+#include <linux/oom.h>
 
 #include <asm/local.h>
 
@@ -41,6 +42,8 @@ int ring_buffer_print_entry_header(struct trace_seq *s)
 			 RINGBUF_TYPE_PADDING);
 	trace_seq_printf(s, "\ttime_extend : type == %d\n",
 			 RINGBUF_TYPE_TIME_EXTEND);
+	trace_seq_printf(s, "\ttime_stamp : type == %d\n",
+			 RINGBUF_TYPE_TIME_STAMP);
 	trace_seq_printf(s, "\tdata max type_len  == %d\n",
 			 RINGBUF_TYPE_DATA_TYPE_LEN_MAX);
 
@@ -140,12 +143,15 @@ int ring_buffer_print_entry_header(struct trace_seq *s)
 
 enum {
 	RB_LEN_TIME_EXTEND = 8,
-	RB_LEN_TIME_STAMP = 16,
+	RB_LEN_TIME_STAMP =  8,
 };
 
 #define skip_time_extend(event) \
 	((struct ring_buffer_event *)((char *)event + RB_LEN_TIME_EXTEND))
 
+#define extended_time(event) \
+	(event->type_len >= RINGBUF_TYPE_TIME_EXTEND)
+
 static inline int rb_null_event(struct ring_buffer_event *event)
 {
 	return event->type_len == RINGBUF_TYPE_PADDING && !event->time_delta;
@@ -209,7 +215,7 @@ rb_event_ts_length(struct ring_buffer_event *event)
 {
 	unsigned len = 0;
 
-	if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) {
+	if (extended_time(event)) {
 		/* time extends include the data event after it */
 		len = RB_LEN_TIME_EXTEND;
 		event = skip_time_extend(event);
@@ -231,7 +237,7 @@ unsigned ring_buffer_event_length(struct ring_buffer_event *event)
 {
 	unsigned length;
 
-	if (event->type_len == RINGBUF_TYPE_TIME_EXTEND)
+	if (extended_time(event))
 		event = skip_time_extend(event);
 
 	length = rb_event_length(event);
@@ -248,7 +254,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_length);
 static __always_inline void *
 rb_event_data(struct ring_buffer_event *event)
 {
-	if (event->type_len == RINGBUF_TYPE_TIME_EXTEND)
+	if (extended_time(event))
 		event = skip_time_extend(event);
 	BUG_ON(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX);
 	/* If length is in len field, then array[0] has the data */
@@ -275,6 +281,27 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data);
 #define TS_MASK		((1ULL << TS_SHIFT) - 1)
 #define TS_DELTA_TEST	(~TS_MASK)
 
+/**
+ * ring_buffer_event_time_stamp - return the event's extended timestamp
+ * @event: the event to get the timestamp of
+ *
+ * Returns the extended timestamp associated with a data event.
+ * An extended time_stamp is a 64-bit timestamp represented
+ * internally in a special way that makes the best use of space
+ * contained within a ring buffer event.  This function decodes
+ * it and maps it to a straight u64 value.
+ */
+u64 ring_buffer_event_time_stamp(struct ring_buffer_event *event)
+{
+	u64 ts;
+
+	ts = event->array[0];
+	ts <<= TS_SHIFT;
+	ts += event->time_delta;
+
+	return ts;
+}
+
 /* Flag when events were overwritten */
 #define RB_MISSED_EVENTS	(1 << 31)
 /* Missed count stored at end */
@@ -451,6 +478,7 @@ struct ring_buffer_per_cpu {
 	struct buffer_page		*reader_page;
 	unsigned long			lost_events;
 	unsigned long			last_overrun;
+	unsigned long			nest;
 	local_t				entries_bytes;
 	local_t				entries;
 	local_t				overrun;
@@ -488,6 +516,7 @@ struct ring_buffer {
 	u64				(*clock)(void);
 
 	struct rb_irq_work		irq_work;
+	bool				time_stamp_abs;
 };
 
 struct ring_buffer_iter {
@@ -1134,30 +1163,60 @@ static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer)
 static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu)
 {
 	struct buffer_page *bpage, *tmp;
+	bool user_thread = current->mm != NULL;
+	gfp_t mflags;
 	long i;
 
+	/*
+	 * Check if the available memory is there first.
+	 * Note, si_mem_available() only gives us a rough estimate of available
+	 * memory. It may not be accurate. But we don't care, we just want
+	 * to prevent doing any allocation when it is obvious that it is
+	 * not going to succeed.
+	 */
+	i = si_mem_available();
+	if (i < nr_pages)
+		return -ENOMEM;
+
+	/*
+	 * __GFP_RETRY_MAYFAIL flag makes sure that the allocation fails
+	 * gracefully without invoking oom-killer and the system is not
+	 * destabilized.
+	 */
+	mflags = GFP_KERNEL | __GFP_RETRY_MAYFAIL;
+
+	/*
+	 * If a user thread allocates too much, and si_mem_available()
+	 * reports there's enough memory, even though there is not.
+	 * Make sure the OOM killer kills this thread. This can happen
+	 * even with RETRY_MAYFAIL because another task may be doing
+	 * an allocation after this task has taken all memory.
+	 * This is the task the OOM killer needs to take out during this
+	 * loop, even if it was triggered by an allocation somewhere else.
+	 */
+	if (user_thread)
+		set_current_oom_origin();
 	for (i = 0; i < nr_pages; i++) {
 		struct page *page;
-		/*
-		 * __GFP_RETRY_MAYFAIL flag makes sure that the allocation fails
-		 * gracefully without invoking oom-killer and the system is not
-		 * destabilized.
-		 */
+
 		bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),
-				    GFP_KERNEL | __GFP_RETRY_MAYFAIL,
-				    cpu_to_node(cpu));
+				    mflags, cpu_to_node(cpu));
 		if (!bpage)
 			goto free_pages;
 
 		list_add(&bpage->list, pages);
 
-		page = alloc_pages_node(cpu_to_node(cpu),
-					GFP_KERNEL | __GFP_RETRY_MAYFAIL, 0);
+		page = alloc_pages_node(cpu_to_node(cpu), mflags, 0);
 		if (!page)
 			goto free_pages;
 		bpage->page = page_address(page);
 		rb_init_page(bpage->page);
+
+		if (user_thread && fatal_signal_pending(current))
+			goto free_pages;
 	}
+	if (user_thread)
+		clear_current_oom_origin();
 
 	return 0;
 
@@ -1166,6 +1225,8 @@ free_pages:
 		list_del_init(&bpage->list);
 		free_buffer_page(bpage);
 	}
+	if (user_thread)
+		clear_current_oom_origin();
 
 	return -ENOMEM;
 }
@@ -1382,6 +1443,16 @@ void ring_buffer_set_clock(struct ring_buffer *buffer,
 	buffer->clock = clock;
 }
 
+void ring_buffer_set_time_stamp_abs(struct ring_buffer *buffer, bool abs)
+{
+	buffer->time_stamp_abs = abs;
+}
+
+bool ring_buffer_time_stamp_abs(struct ring_buffer *buffer)
+{
+	return buffer->time_stamp_abs;
+}
+
 static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer);
 
 static inline unsigned long rb_page_entries(struct buffer_page *bpage)
@@ -2206,12 +2277,15 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
 
 /* Slow path, do not inline */
 static noinline struct ring_buffer_event *
-rb_add_time_stamp(struct ring_buffer_event *event, u64 delta)
+rb_add_time_stamp(struct ring_buffer_event *event, u64 delta, bool abs)
 {
-	event->type_len = RINGBUF_TYPE_TIME_EXTEND;
+	if (abs)
+		event->type_len = RINGBUF_TYPE_TIME_STAMP;
+	else
+		event->type_len = RINGBUF_TYPE_TIME_EXTEND;
 
-	/* Not the first event on the page? */
-	if (rb_event_index(event)) {
+	/* Not the first event on the page, or not delta? */
+	if (abs || rb_event_index(event)) {
 		event->time_delta = delta & TS_MASK;
 		event->array[0] = delta >> TS_SHIFT;
 	} else {
@@ -2254,7 +2328,9 @@ rb_update_event(struct ring_buffer_per_cpu *cpu_buffer,
 	 * add it to the start of the resevered space.
 	 */
 	if (unlikely(info->add_timestamp)) {
-		event = rb_add_time_stamp(event, delta);
+		bool abs = ring_buffer_time_stamp_abs(cpu_buffer->buffer);
+
+		event = rb_add_time_stamp(event, info->delta, abs);
 		length -= RB_LEN_TIME_EXTEND;
 		delta = 0;
 	}
@@ -2442,7 +2518,7 @@ static __always_inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer
 
 static inline void rb_event_discard(struct ring_buffer_event *event)
 {
-	if (event->type_len == RINGBUF_TYPE_TIME_EXTEND)
+	if (extended_time(event))
 		event = skip_time_extend(event);
 
 	/* array[0] holds the actual length for the discarded event */
@@ -2486,10 +2562,11 @@ rb_update_write_stamp(struct ring_buffer_per_cpu *cpu_buffer,
 			cpu_buffer->write_stamp =
 				cpu_buffer->commit_page->page->time_stamp;
 		else if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) {
-			delta = event->array[0];
-			delta <<= TS_SHIFT;
-			delta += event->time_delta;
+			delta = ring_buffer_event_time_stamp(event);
 			cpu_buffer->write_stamp += delta;
+		} else if (event->type_len == RINGBUF_TYPE_TIME_STAMP) {
+			delta = ring_buffer_event_time_stamp(event);
+			cpu_buffer->write_stamp = delta;
 		} else
 			cpu_buffer->write_stamp += event->time_delta;
 	}
@@ -2581,10 +2658,10 @@ trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer)
 		bit = pc & NMI_MASK ? RB_CTX_NMI :
 			pc & HARDIRQ_MASK ? RB_CTX_IRQ : RB_CTX_SOFTIRQ;
 
-	if (unlikely(val & (1 << bit)))
+	if (unlikely(val & (1 << (bit + cpu_buffer->nest))))
 		return 1;
 
-	val |= (1 << bit);
+	val |= (1 << (bit + cpu_buffer->nest));
 	cpu_buffer->current_context = val;
 
 	return 0;
@@ -2593,7 +2670,57 @@ trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer)
 static __always_inline void
 trace_recursive_unlock(struct ring_buffer_per_cpu *cpu_buffer)
 {
-	cpu_buffer->current_context &= cpu_buffer->current_context - 1;
+	cpu_buffer->current_context &=
+		cpu_buffer->current_context - (1 << cpu_buffer->nest);
+}
+
+/* The recursive locking above uses 4 bits */
+#define NESTED_BITS 4
+
+/**
+ * ring_buffer_nest_start - Allow to trace while nested
+ * @buffer: The ring buffer to modify
+ *
+ * The ring buffer has a safty mechanism to prevent recursion.
+ * But there may be a case where a trace needs to be done while
+ * tracing something else. In this case, calling this function
+ * will allow this function to nest within a currently active
+ * ring_buffer_lock_reserve().
+ *
+ * Call this function before calling another ring_buffer_lock_reserve() and
+ * call ring_buffer_nest_end() after the nested ring_buffer_unlock_commit().
+ */
+void ring_buffer_nest_start(struct ring_buffer *buffer)
+{
+	struct ring_buffer_per_cpu *cpu_buffer;
+	int cpu;
+
+	/* Enabled by ring_buffer_nest_end() */
+	preempt_disable_notrace();
+	cpu = raw_smp_processor_id();
+	cpu_buffer = buffer->buffers[cpu];
+	/* This is the shift value for the above recusive locking */
+	cpu_buffer->nest += NESTED_BITS;
+}
+
+/**
+ * ring_buffer_nest_end - Allow to trace while nested
+ * @buffer: The ring buffer to modify
+ *
+ * Must be called after ring_buffer_nest_start() and after the
+ * ring_buffer_unlock_commit().
+ */
+void ring_buffer_nest_end(struct ring_buffer *buffer)
+{
+	struct ring_buffer_per_cpu *cpu_buffer;
+	int cpu;
+
+	/* disabled by ring_buffer_nest_start() */
+	cpu = raw_smp_processor_id();
+	cpu_buffer = buffer->buffers[cpu];
+	/* This is the shift value for the above recusive locking */
+	cpu_buffer->nest -= NESTED_BITS;
+	preempt_enable_notrace();
 }
 
 /**
@@ -2637,7 +2764,8 @@ rb_handle_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
 		  sched_clock_stable() ? "" :
 		  "If you just came from a suspend/resume,\n"
 		  "please switch to the trace global clock:\n"
-		  "  echo global > /sys/kernel/debug/tracing/trace_clock\n");
+		  "  echo global > /sys/kernel/debug/tracing/trace_clock\n"
+		  "or add trace_clock=global to the kernel command line\n");
 	info->add_timestamp = 1;
 }
 
@@ -2669,7 +2797,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 	 * If this is the first commit on the page, then it has the same
 	 * timestamp as the page itself.
 	 */
-	if (!tail)
+	if (!tail && !ring_buffer_time_stamp_abs(cpu_buffer->buffer))
 		info->delta = 0;
 
 	/* See if we shot pass the end of this buffer page */
@@ -2746,8 +2874,11 @@ rb_reserve_next_event(struct ring_buffer *buffer,
 	/* make sure this diff is calculated here */
 	barrier();
 
-	/* Did the write stamp get updated already? */
-	if (likely(info.ts >= cpu_buffer->write_stamp)) {
+	if (ring_buffer_time_stamp_abs(buffer)) {
+		info.delta = info.ts;
+		rb_handle_timestamp(cpu_buffer, &info);
+	} else /* Did the write stamp get updated already? */
+		if (likely(info.ts >= cpu_buffer->write_stamp)) {
 		info.delta = diff;
 		if (unlikely(test_time_stamp(info.delta)))
 			rb_handle_timestamp(cpu_buffer, &info);
@@ -3429,14 +3560,13 @@ rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer,
 		return;
 
 	case RINGBUF_TYPE_TIME_EXTEND:
-		delta = event->array[0];
-		delta <<= TS_SHIFT;
-		delta += event->time_delta;
+		delta = ring_buffer_event_time_stamp(event);
 		cpu_buffer->read_stamp += delta;
 		return;
 
 	case RINGBUF_TYPE_TIME_STAMP:
-		/* FIXME: not implemented */
+		delta = ring_buffer_event_time_stamp(event);
+		cpu_buffer->read_stamp = delta;
 		return;
 
 	case RINGBUF_TYPE_DATA:
@@ -3460,14 +3590,13 @@ rb_update_iter_read_stamp(struct ring_buffer_iter *iter,
 		return;
 
 	case RINGBUF_TYPE_TIME_EXTEND:
-		delta = event->array[0];
-		delta <<= TS_SHIFT;
-		delta += event->time_delta;
+		delta = ring_buffer_event_time_stamp(event);
 		iter->read_stamp += delta;
 		return;
 
 	case RINGBUF_TYPE_TIME_STAMP:
-		/* FIXME: not implemented */
+		delta = ring_buffer_event_time_stamp(event);
+		iter->read_stamp = delta;
 		return;
 
 	case RINGBUF_TYPE_DATA:
@@ -3691,6 +3820,8 @@ rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts,
 	struct buffer_page *reader;
 	int nr_loops = 0;
 
+	if (ts)
+		*ts = 0;
  again:
 	/*
 	 * We repeat when a time extend is encountered.
@@ -3727,12 +3858,17 @@ rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts,
 		goto again;
 
 	case RINGBUF_TYPE_TIME_STAMP:
-		/* FIXME: not implemented */
+		if (ts) {
+			*ts = ring_buffer_event_time_stamp(event);
+			ring_buffer_normalize_time_stamp(cpu_buffer->buffer,
+							 cpu_buffer->cpu, ts);
+		}
+		/* Internal data, OK to advance */
 		rb_advance_reader(cpu_buffer);
 		goto again;
 
 	case RINGBUF_TYPE_DATA:
-		if (ts) {
+		if (ts && !(*ts)) {
 			*ts = cpu_buffer->read_stamp + event->time_delta;
 			ring_buffer_normalize_time_stamp(cpu_buffer->buffer,
 							 cpu_buffer->cpu, ts);
@@ -3757,6 +3893,9 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
 	struct ring_buffer_event *event;
 	int nr_loops = 0;
 
+	if (ts)
+		*ts = 0;
+
 	cpu_buffer = iter->cpu_buffer;
 	buffer = cpu_buffer->buffer;
 
@@ -3809,12 +3948,17 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
 		goto again;
 
 	case RINGBUF_TYPE_TIME_STAMP:
-		/* FIXME: not implemented */
+		if (ts) {
+			*ts = ring_buffer_event_time_stamp(event);
+			ring_buffer_normalize_time_stamp(cpu_buffer->buffer,
+							 cpu_buffer->cpu, ts);
+		}
+		/* Internal data, OK to advance */
 		rb_advance_iter(iter);
 		goto again;
 
 	case RINGBUF_TYPE_DATA:
-		if (ts) {
+		if (ts && !(*ts)) {
 			*ts = iter->read_stamp + event->time_delta;
 			ring_buffer_normalize_time_stamp(buffer,
 							 cpu_buffer->cpu, ts);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5071931eb943..dfbcf9ee1447 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -41,6 +41,7 @@
 #include <linux/nmi.h>
 #include <linux/fs.h>
 #include <linux/trace.h>
+#include <linux/sched/clock.h>
 #include <linux/sched/rt.h>
 
 #include "trace.h"
@@ -1168,6 +1169,14 @@ static struct {
 	ARCH_TRACE_CLOCKS
 };
 
+bool trace_clock_in_ns(struct trace_array *tr)
+{
+	if (trace_clocks[tr->clock_id].in_ns)
+		return true;
+
+	return false;
+}
+
 /*
  * trace_parser_get_init - gets the buffer for trace parser
  */
@@ -2269,7 +2278,7 @@ trace_event_buffer_lock_reserve(struct ring_buffer **current_rb,
 
 	*current_rb = trace_file->tr->trace_buffer.buffer;
 
-	if ((trace_file->flags &
+	if (!ring_buffer_time_stamp_abs(*current_rb) && (trace_file->flags &
 	     (EVENT_FILE_FL_SOFT_DISABLED | EVENT_FILE_FL_FILTERED)) &&
 	    (entry = this_cpu_read(trace_buffered_event))) {
 		/* Try to use the per cpu buffer first */
@@ -4515,6 +4524,9 @@ static const char readme_msg[] =
 #ifdef CONFIG_X86_64
 	"     x86-tsc:   TSC cycle counter\n"
 #endif
+	"\n  timestamp_mode\t-view the mode used to timestamp events\n"
+	"       delta:   Delta difference against a buffer-wide timestamp\n"
+	"    absolute:   Absolute (standalone) timestamp\n"
 	"\n  trace_marker\t\t- Writes into this file writes into the kernel buffer\n"
 	"\n  trace_marker_raw\t\t- Writes into this file writes binary data into the kernel buffer\n"
 	"  tracing_cpumask\t- Limit which CPUs to trace\n"
@@ -4691,8 +4703,9 @@ static const char readme_msg[] =
 	"\t            .sym        display an address as a symbol\n"
 	"\t            .sym-offset display an address as a symbol and offset\n"
 	"\t            .execname   display a common_pid as a program name\n"
-	"\t            .syscall    display a syscall id as a syscall name\n\n"
-	"\t            .log2       display log2 value rather than raw number\n\n"
+	"\t            .syscall    display a syscall id as a syscall name\n"
+	"\t            .log2       display log2 value rather than raw number\n"
+	"\t            .usecs      display a common_timestamp in microseconds\n\n"
 	"\t    The 'pause' parameter can be used to pause an existing hist\n"
 	"\t    trigger or to start a hist trigger but not log any events\n"
 	"\t    until told to do so.  'continue' can be used to start or\n"
@@ -6202,7 +6215,7 @@ static int tracing_clock_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int tracing_set_clock(struct trace_array *tr, const char *clockstr)
+int tracing_set_clock(struct trace_array *tr, const char *clockstr)
 {
 	int i;
 
@@ -6282,6 +6295,71 @@ static int tracing_clock_open(struct inode *inode, struct file *file)
 	return ret;
 }
 
+static int tracing_time_stamp_mode_show(struct seq_file *m, void *v)
+{
+	struct trace_array *tr = m->private;
+
+	mutex_lock(&trace_types_lock);
+
+	if (ring_buffer_time_stamp_abs(tr->trace_buffer.buffer))
+		seq_puts(m, "delta [absolute]\n");
+	else
+		seq_puts(m, "[delta] absolute\n");
+
+	mutex_unlock(&trace_types_lock);
+
+	return 0;
+}
+
+static int tracing_time_stamp_mode_open(struct inode *inode, struct file *file)
+{
+	struct trace_array *tr = inode->i_private;
+	int ret;
+
+	if (tracing_disabled)
+		return -ENODEV;
+
+	if (trace_array_get(tr))
+		return -ENODEV;
+
+	ret = single_open(file, tracing_time_stamp_mode_show, inode->i_private);
+	if (ret < 0)
+		trace_array_put(tr);
+
+	return ret;
+}
+
+int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs)
+{
+	int ret = 0;
+
+	mutex_lock(&trace_types_lock);
+
+	if (abs && tr->time_stamp_abs_ref++)
+		goto out;
+
+	if (!abs) {
+		if (WARN_ON_ONCE(!tr->time_stamp_abs_ref)) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		if (--tr->time_stamp_abs_ref)
+			goto out;
+	}
+
+	ring_buffer_set_time_stamp_abs(tr->trace_buffer.buffer, abs);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+	if (tr->max_buffer.buffer)
+		ring_buffer_set_time_stamp_abs(tr->max_buffer.buffer, abs);
+#endif
+ out:
+	mutex_unlock(&trace_types_lock);
+
+	return ret;
+}
+
 struct ftrace_buffer_info {
 	struct trace_iterator	iter;
 	void			*spare;
@@ -6529,6 +6607,13 @@ static const struct file_operations trace_clock_fops = {
 	.write		= tracing_clock_write,
 };
 
+static const struct file_operations trace_time_stamp_mode_fops = {
+	.open		= tracing_time_stamp_mode_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= tracing_single_release_tr,
+};
+
 #ifdef CONFIG_TRACER_SNAPSHOT
 static const struct file_operations snapshot_fops = {
 	.open		= tracing_snapshot_open,
@@ -7699,6 +7784,7 @@ static int instance_mkdir(const char *name)
 
 	INIT_LIST_HEAD(&tr->systems);
 	INIT_LIST_HEAD(&tr->events);
+	INIT_LIST_HEAD(&tr->hist_vars);
 
 	if (allocate_trace_buffers(tr, trace_buf_size) < 0)
 		goto out_free_tr;
@@ -7851,6 +7937,9 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 	trace_create_file("tracing_on", 0644, d_tracer,
 			  tr, &rb_simple_fops);
 
+	trace_create_file("timestamp_mode", 0444, d_tracer, tr,
+			  &trace_time_stamp_mode_fops);
+
 	create_trace_options_dir(tr);
 
 #if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
@@ -8446,6 +8535,7 @@ __init static int tracer_alloc_buffers(void)
 
 	INIT_LIST_HEAD(&global_trace.systems);
 	INIT_LIST_HEAD(&global_trace.events);
+	INIT_LIST_HEAD(&global_trace.hist_vars);
 	list_add(&global_trace.list, &ftrace_trace_arrays);
 
 	apply_trace_boot_options();
@@ -8507,3 +8597,21 @@ __init static int clear_boot_tracer(void)
 
 fs_initcall(tracer_init_tracefs);
 late_initcall_sync(clear_boot_tracer);
+
+#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
+__init static int tracing_set_default_clock(void)
+{
+	/* sched_clock_stable() is determined in late_initcall */
+	if (!trace_boot_clock && !sched_clock_stable()) {
+		printk(KERN_WARNING
+		       "Unstable clock detected, switching default tracing clock to \"global\"\n"
+		       "If you want to keep using the local clock, then add:\n"
+		       "  \"trace_clock=local\"\n"
+		       "on the kernel command line\n");
+		tracing_set_clock(&global_trace, "global");
+	}
+
+	return 0;
+}
+late_initcall_sync(tracing_set_default_clock);
+#endif
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2a6d0325a761..6fb46a06c9dc 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -273,6 +273,8 @@ struct trace_array {
 	/* function tracing enabled */
 	int			function_enabled;
 #endif
+	int			time_stamp_abs_ref;
+	struct list_head	hist_vars;
 };
 
 enum {
@@ -286,6 +288,11 @@ extern struct mutex trace_types_lock;
 extern int trace_array_get(struct trace_array *tr);
 extern void trace_array_put(struct trace_array *tr);
 
+extern int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs);
+extern int tracing_set_clock(struct trace_array *tr, const char *clockstr);
+
+extern bool trace_clock_in_ns(struct trace_array *tr);
+
 /*
  * The global tracer (top) should be the first trace array added,
  * but we check the flag anyway.
@@ -1209,12 +1216,11 @@ struct ftrace_event_field {
 	int			is_signed;
 };
 
+struct prog_entry;
+
 struct event_filter {
-	int			n_preds;	/* Number assigned */
-	int			a_preds;	/* allocated */
-	struct filter_pred __rcu	*preds;
-	struct filter_pred __rcu	*root;
-	char				*filter_string;
+	struct prog_entry __rcu	*prog;
+	char			*filter_string;
 };
 
 struct event_subsystem {
@@ -1291,7 +1297,7 @@ __event_trigger_test_discard(struct trace_event_file *file,
 	unsigned long eflags = file->flags;
 
 	if (eflags & EVENT_FILE_FL_TRIGGER_COND)
-		*tt = event_triggers_call(file, entry);
+		*tt = event_triggers_call(file, entry, event);
 
 	if (test_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags) ||
 	    (unlikely(file->flags & EVENT_FILE_FL_FILTERED) &&
@@ -1328,7 +1334,7 @@ event_trigger_unlock_commit(struct trace_event_file *file,
 		trace_buffer_unlock_commit(file->tr, buffer, event, irq_flags, pc);
 
 	if (tt)
-		event_triggers_post_call(file, tt, entry);
+		event_triggers_post_call(file, tt, entry, event);
 }
 
 /**
@@ -1361,7 +1367,7 @@ event_trigger_unlock_commit_regs(struct trace_event_file *file,
 						irq_flags, pc, regs);
 
 	if (tt)
-		event_triggers_post_call(file, tt, entry);
+		event_triggers_post_call(file, tt, entry, event);
 }
 
 #define FILTER_PRED_INVALID	((unsigned short)-1)
@@ -1406,12 +1412,8 @@ struct filter_pred {
 	unsigned short		*ops;
 	struct ftrace_event_field *field;
 	int 			offset;
-	int 			not;
+	int			not;
 	int 			op;
-	unsigned short		index;
-	unsigned short		parent;
-	unsigned short		left;
-	unsigned short		right;
 };
 
 static inline bool is_string_field(struct ftrace_event_field *field)
@@ -1543,6 +1545,8 @@ extern void pause_named_trigger(struct event_trigger_data *data);
 extern void unpause_named_trigger(struct event_trigger_data *data);
 extern void set_named_trigger_data(struct event_trigger_data *data,
 				   struct event_trigger_data *named_data);
+extern struct event_trigger_data *
+get_named_trigger_data(struct event_trigger_data *data);
 extern int register_event_command(struct event_command *cmd);
 extern int unregister_event_command(struct event_command *cmd);
 extern int register_trigger_hist_enable_disable_cmds(void);
@@ -1586,7 +1590,8 @@ extern int register_trigger_hist_enable_disable_cmds(void);
  */
 struct event_trigger_ops {
 	void			(*func)(struct event_trigger_data *data,
-					void *rec);
+					void *rec,
+					struct ring_buffer_event *rbe);
 	int			(*init)(struct event_trigger_ops *ops,
 					struct event_trigger_data *data);
 	void			(*free)(struct event_trigger_ops *ops,
diff --git a/kernel/trace/trace_clock.c b/kernel/trace/trace_clock.c
index 5fdc779f411d..d8a188e0418a 100644
--- a/kernel/trace/trace_clock.c
+++ b/kernel/trace/trace_clock.c
@@ -96,7 +96,7 @@ u64 notrace trace_clock_global(void)
 	int this_cpu;
 	u64 now;
 
-	local_irq_save(flags);
+	raw_local_irq_save(flags);
 
 	this_cpu = raw_smp_processor_id();
 	now = sched_clock_cpu(this_cpu);
@@ -122,7 +122,7 @@ u64 notrace trace_clock_global(void)
 	arch_spin_unlock(&trace_clock_struct.lock);
 
  out:
-	local_irq_restore(flags);
+	raw_local_irq_restore(flags);
 
 	return now;
 }
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index a764aec3c9a1..1bda4ec95e18 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -33,163 +33,595 @@
 	"# Only events with the given fields will be affected.\n"	\
 	"# If no events are modified, an error message will be displayed here"
 
-enum filter_op_ids
-{
-	OP_OR,
-	OP_AND,
-	OP_GLOB,
-	OP_NE,
-	OP_EQ,
-	OP_LT,
-	OP_LE,
-	OP_GT,
-	OP_GE,
-	OP_BAND,
-	OP_NOT,
-	OP_NONE,
-	OP_OPEN_PAREN,
-};
+/* Due to token parsing '<=' must be before '<' and '>=' must be before '>' */
+#define OPS					\
+	C( OP_GLOB,	"~"  ),			\
+	C( OP_NE,	"!=" ),			\
+	C( OP_EQ,	"==" ),			\
+	C( OP_LE,	"<=" ),			\
+	C( OP_LT,	"<"  ),			\
+	C( OP_GE,	">=" ),			\
+	C( OP_GT,	">"  ),			\
+	C( OP_BAND,	"&"  ),			\
+	C( OP_MAX,	NULL )
 
-struct filter_op {
-	int id;
-	char *string;
-	int precedence;
-};
+#undef C
+#define C(a, b)	a
 
-/* Order must be the same as enum filter_op_ids above */
-static struct filter_op filter_ops[] = {
-	{ OP_OR,	"||",		1 },
-	{ OP_AND,	"&&",		2 },
-	{ OP_GLOB,	"~",		4 },
-	{ OP_NE,	"!=",		4 },
-	{ OP_EQ,	"==",		4 },
-	{ OP_LT,	"<",		5 },
-	{ OP_LE,	"<=",		5 },
-	{ OP_GT,	">",		5 },
-	{ OP_GE,	">=",		5 },
-	{ OP_BAND,	"&",		6 },
-	{ OP_NOT,	"!",		6 },
-	{ OP_NONE,	"OP_NONE",	0 },
-	{ OP_OPEN_PAREN, "(",		0 },
-};
+enum filter_op_ids { OPS };
 
-enum {
-	FILT_ERR_NONE,
-	FILT_ERR_INVALID_OP,
-	FILT_ERR_UNBALANCED_PAREN,
-	FILT_ERR_TOO_MANY_OPERANDS,
-	FILT_ERR_OPERAND_TOO_LONG,
-	FILT_ERR_FIELD_NOT_FOUND,
-	FILT_ERR_ILLEGAL_FIELD_OP,
-	FILT_ERR_ILLEGAL_INTVAL,
-	FILT_ERR_BAD_SUBSYS_FILTER,
-	FILT_ERR_TOO_MANY_PREDS,
-	FILT_ERR_MISSING_FIELD,
-	FILT_ERR_INVALID_FILTER,
-	FILT_ERR_IP_FIELD_ONLY,
-	FILT_ERR_ILLEGAL_NOT_OP,
-};
+#undef C
+#define C(a, b)	b
 
-static char *err_text[] = {
-	"No error",
-	"Invalid operator",
-	"Unbalanced parens",
-	"Too many operands",
-	"Operand too long",
-	"Field not found",
-	"Illegal operation for field type",
-	"Illegal integer value",
-	"Couldn't find or set field in one of a subsystem's events",
-	"Too many terms in predicate expression",
-	"Missing field name and/or value",
-	"Meaningless filter expression",
-	"Only 'ip' field is supported for function trace",
-	"Illegal use of '!'",
-};
+static const char * ops[] = { OPS };
 
-struct opstack_op {
-	enum filter_op_ids op;
-	struct list_head list;
-};
+/*
+ * pred functions are OP_LE, OP_LT, OP_GE, OP_GT, and OP_BAND
+ * pred_funcs_##type below must match the order of them above.
+ */
+#define PRED_FUNC_START			OP_LE
+#define PRED_FUNC_MAX			(OP_BAND - PRED_FUNC_START)
+
+#define ERRORS								\
+	C(NONE,			"No error"),				\
+	C(INVALID_OP,		"Invalid operator"),			\
+	C(TOO_MANY_OPEN,	"Too many '('"),			\
+	C(TOO_MANY_CLOSE,	"Too few '('"),				\
+	C(MISSING_QUOTE,	"Missing matching quote"),		\
+	C(OPERAND_TOO_LONG,	"Operand too long"),			\
+	C(EXPECT_STRING,	"Expecting string field"),		\
+	C(EXPECT_DIGIT,		"Expecting numeric field"),		\
+	C(ILLEGAL_FIELD_OP,	"Illegal operation for field type"),	\
+	C(FIELD_NOT_FOUND,	"Field not found"),			\
+	C(ILLEGAL_INTVAL,	"Illegal integer value"),		\
+	C(BAD_SUBSYS_FILTER,	"Couldn't find or set field in one of a subsystem's events"), \
+	C(TOO_MANY_PREDS,	"Too many terms in predicate expression"), \
+	C(INVALID_FILTER,	"Meaningless filter expression"),	\
+	C(IP_FIELD_ONLY,	"Only 'ip' field is supported for function trace"), \
+	C(INVALID_VALUE,	"Invalid value (did you forget quotes)?"),
+
+#undef C
+#define C(a, b)		FILT_ERR_##a
+
+enum { ERRORS };
+
+#undef C
+#define C(a, b)		b
+
+static char *err_text[] = { ERRORS };
+
+/* Called after a '!' character but "!=" and "!~" are not "not"s */
+static bool is_not(const char *str)
+{
+	switch (str[1]) {
+	case '=':
+	case '~':
+		return false;
+	}
+	return true;
+}
 
-struct postfix_elt {
-	enum filter_op_ids op;
-	char *operand;
-	struct list_head list;
+/**
+ * prog_entry - a singe entry in the filter program
+ * @target:	     Index to jump to on a branch (actually one minus the index)
+ * @when_to_branch:  The value of the result of the predicate to do a branch
+ * @pred:	     The predicate to execute.
+ */
+struct prog_entry {
+	int			target;
+	int			when_to_branch;
+	struct filter_pred	*pred;
 };
 
-struct filter_parse_state {
-	struct filter_op *ops;
-	struct list_head opstack;
-	struct list_head postfix;
+/**
+ * update_preds- assign a program entry a label target
+ * @prog: The program array
+ * @N: The index of the current entry in @prog
+ * @when_to_branch: What to assign a program entry for its branch condition
+ *
+ * The program entry at @N has a target that points to the index of a program
+ * entry that can have its target and when_to_branch fields updated.
+ * Update the current program entry denoted by index @N target field to be
+ * that of the updated entry. This will denote the entry to update if
+ * we are processing an "||" after an "&&"
+ */
+static void update_preds(struct prog_entry *prog, int N, int invert)
+{
+	int t, s;
+
+	t = prog[N].target;
+	s = prog[t].target;
+	prog[t].when_to_branch = invert;
+	prog[t].target = N;
+	prog[N].target = s;
+}
+
+struct filter_parse_error {
 	int lasterr;
 	int lasterr_pos;
-
-	struct {
-		char *string;
-		unsigned int cnt;
-		unsigned int tail;
-	} infix;
-
-	struct {
-		char string[MAX_FILTER_STR_VAL];
-		int pos;
-		unsigned int tail;
-	} operand;
 };
 
-struct pred_stack {
-	struct filter_pred	**preds;
-	int			index;
+static void parse_error(struct filter_parse_error *pe, int err, int pos)
+{
+	pe->lasterr = err;
+	pe->lasterr_pos = pos;
+}
+
+typedef int (*parse_pred_fn)(const char *str, void *data, int pos,
+			     struct filter_parse_error *pe,
+			     struct filter_pred **pred);
+
+enum {
+	INVERT		= 1,
+	PROCESS_AND	= 2,
+	PROCESS_OR	= 4,
 };
 
-/* If not of not match is equal to not of not, then it is a match */
+/*
+ * Without going into a formal proof, this explains the method that is used in
+ * parsing the logical expressions.
+ *
+ * For example, if we have: "a && !(!b || (c && g)) || d || e && !f"
+ * The first pass will convert it into the following program:
+ *
+ * n1: r=a;       l1: if (!r) goto l4;
+ * n2: r=b;       l2: if (!r) goto l4;
+ * n3: r=c; r=!r; l3: if (r) goto l4;
+ * n4: r=g; r=!r; l4: if (r) goto l5;
+ * n5: r=d;       l5: if (r) goto T
+ * n6: r=e;       l6: if (!r) goto l7;
+ * n7: r=f; r=!r; l7: if (!r) goto F
+ * T: return TRUE
+ * F: return FALSE
+ *
+ * To do this, we use a data structure to represent each of the above
+ * predicate and conditions that has:
+ *
+ *  predicate, when_to_branch, invert, target
+ *
+ * The "predicate" will hold the function to determine the result "r".
+ * The "when_to_branch" denotes what "r" should be if a branch is to be taken
+ * "&&" would contain "!r" or (0) and "||" would contain "r" or (1).
+ * The "invert" holds whether the value should be reversed before testing.
+ * The "target" contains the label "l#" to jump to.
+ *
+ * A stack is created to hold values when parentheses are used.
+ *
+ * To simplify the logic, the labels will start at 0 and not 1.
+ *
+ * The possible invert values are 1 and 0. The number of "!"s that are in scope
+ * before the predicate determines the invert value, if the number is odd then
+ * the invert value is 1 and 0 otherwise. This means the invert value only
+ * needs to be toggled when a new "!" is introduced compared to what is stored
+ * on the stack, where parentheses were used.
+ *
+ * The top of the stack and "invert" are initialized to zero.
+ *
+ * ** FIRST PASS **
+ *
+ * #1 A loop through all the tokens is done:
+ *
+ * #2 If the token is an "(", the stack is push, and the current stack value
+ *    gets the current invert value, and the loop continues to the next token.
+ *    The top of the stack saves the "invert" value to keep track of what
+ *    the current inversion is. As "!(a && !b || c)" would require all
+ *    predicates being affected separately by the "!" before the parentheses.
+ *    And that would end up being equivalent to "(!a || b) && !c"
+ *
+ * #3 If the token is an "!", the current "invert" value gets inverted, and
+ *    the loop continues. Note, if the next token is a predicate, then
+ *    this "invert" value is only valid for the current program entry,
+ *    and does not affect other predicates later on.
+ *
+ * The only other acceptable token is the predicate string.
+ *
+ * #4 A new entry into the program is added saving: the predicate and the
+ *    current value of "invert". The target is currently assigned to the
+ *    previous program index (this will not be its final value).
+ *
+ * #5 We now enter another loop and look at the next token. The only valid
+ *    tokens are ")", "&&", "||" or end of the input string "\0".
+ *
+ * #6 The invert variable is reset to the current value saved on the top of
+ *    the stack.
+ *
+ * #7 The top of the stack holds not only the current invert value, but also
+ *    if a "&&" or "||" needs to be processed. Note, the "&&" takes higher
+ *    precedence than "||". That is "a && b || c && d" is equivalent to
+ *    "(a && b) || (c && d)". Thus the first thing to do is to see if "&&" needs
+ *    to be processed. This is the case if an "&&" was the last token. If it was
+ *    then we call update_preds(). This takes the program, the current index in
+ *    the program, and the current value of "invert".  More will be described
+ *    below about this function.
+ *
+ * #8 If the next token is "&&" then we set a flag in the top of the stack
+ *    that denotes that "&&" needs to be processed, break out of this loop
+ *    and continue with the outer loop.
+ *
+ * #9 Otherwise, if a "||" needs to be processed then update_preds() is called.
+ *    This is called with the program, the current index in the program, but
+ *    this time with an inverted value of "invert" (that is !invert). This is
+ *    because the value taken will become the "when_to_branch" value of the
+ *    program.
+ *    Note, this is called when the next token is not an "&&". As stated before,
+ *    "&&" takes higher precedence, and "||" should not be processed yet if the
+ *    next logical operation is "&&".
+ *
+ * #10 If the next token is "||" then we set a flag in the top of the stack
+ *     that denotes that "||" needs to be processed, break out of this loop
+ *     and continue with the outer loop.
+ *
+ * #11 If this is the end of the input string "\0" then we break out of both
+ *     loops.
+ *
+ * #12 Otherwise, the next token is ")", where we pop the stack and continue
+ *     this inner loop.
+ *
+ * Now to discuss the update_pred() function, as that is key to the setting up
+ * of the program. Remember the "target" of the program is initialized to the
+ * previous index and not the "l" label. The target holds the index into the
+ * program that gets affected by the operand. Thus if we have something like
+ *  "a || b && c", when we process "a" the target will be "-1" (undefined).
+ * When we process "b", its target is "0", which is the index of "a", as that's
+ * the predicate that is affected by "||". But because the next token after "b"
+ * is "&&" we don't call update_preds(). Instead continue to "c". As the
+ * next token after "c" is not "&&" but the end of input, we first process the
+ * "&&" by calling update_preds() for the "&&" then we process the "||" by
+ * callin updates_preds() with the values for processing "||".
+ *
+ * What does that mean? What update_preds() does is to first save the "target"
+ * of the program entry indexed by the current program entry's "target"
+ * (remember the "target" is initialized to previous program entry), and then
+ * sets that "target" to the current index which represents the label "l#".
+ * That entry's "when_to_branch" is set to the value passed in (the "invert"
+ * or "!invert"). Then it sets the current program entry's target to the saved
+ * "target" value (the old value of the program that had its "target" updated
+ * to the label).
+ *
+ * Looking back at "a || b && c", we have the following steps:
+ *  "a"  - prog[0] = { "a", X, -1 } // pred, when_to_branch, target
+ *  "||" - flag that we need to process "||"; continue outer loop
+ *  "b"  - prog[1] = { "b", X, 0 }
+ *  "&&" - flag that we need to process "&&"; continue outer loop
+ * (Notice we did not process "||")
+ *  "c"  - prog[2] = { "c", X, 1 }
+ *  update_preds(prog, 2, 0); // invert = 0 as we are processing "&&"
+ *    t = prog[2].target; // t = 1
+ *    s = prog[t].target; // s = 0
+ *    prog[t].target = 2; // Set target to "l2"
+ *    prog[t].when_to_branch = 0;
+ *    prog[2].target = s;
+ * update_preds(prog, 2, 1); // invert = 1 as we are now processing "||"
+ *    t = prog[2].target; // t = 0
+ *    s = prog[t].target; // s = -1
+ *    prog[t].target = 2; // Set target to "l2"
+ *    prog[t].when_to_branch = 1;
+ *    prog[2].target = s;
+ *
+ * #13 Which brings us to the final step of the first pass, which is to set
+ *     the last program entry's when_to_branch and target, which will be
+ *     when_to_branch = 0; target = N; ( the label after the program entry after
+ *     the last program entry processed above).
+ *
+ * If we denote "TRUE" to be the entry after the last program entry processed,
+ * and "FALSE" the program entry after that, we are now done with the first
+ * pass.
+ *
+ * Making the above "a || b && c" have a progam of:
+ *  prog[0] = { "a", 1, 2 }
+ *  prog[1] = { "b", 0, 2 }
+ *  prog[2] = { "c", 0, 3 }
+ *
+ * Which translates into:
+ * n0: r = a; l0: if (r) goto l2;
+ * n1: r = b; l1: if (!r) goto l2;
+ * n2: r = c; l2: if (!r) goto l3;  // Which is the same as "goto F;"
+ * T: return TRUE; l3:
+ * F: return FALSE
+ *
+ * Although, after the first pass, the program is correct, it is
+ * inefficient. The simple sample of "a || b && c" could be easily been
+ * converted into:
+ * n0: r = a; if (r) goto T
+ * n1: r = b; if (!r) goto F
+ * n2: r = c; if (!r) goto F
+ * T: return TRUE;
+ * F: return FALSE;
+ *
+ * The First Pass is over the input string. The next too passes are over
+ * the program itself.
+ *
+ * ** SECOND PASS **
+ *
+ * Which brings us to the second pass. If a jump to a label has the
+ * same condition as that label, it can instead jump to its target.
+ * The original example of "a && !(!b || (c && g)) || d || e && !f"
+ * where the first pass gives us:
+ *
+ * n1: r=a;       l1: if (!r) goto l4;
+ * n2: r=b;       l2: if (!r) goto l4;
+ * n3: r=c; r=!r; l3: if (r) goto l4;
+ * n4: r=g; r=!r; l4: if (r) goto l5;
+ * n5: r=d;       l5: if (r) goto T
+ * n6: r=e;       l6: if (!r) goto l7;
+ * n7: r=f; r=!r; l7: if (!r) goto F:
+ * T: return TRUE;
+ * F: return FALSE
+ *
+ * We can see that "l3: if (r) goto l4;" and at l4, we have "if (r) goto l5;".
+ * And "l5: if (r) goto T", we could optimize this by converting l3 and l4
+ * to go directly to T. To accomplish this, we start from the last
+ * entry in the program and work our way back. If the target of the entry
+ * has the same "when_to_branch" then we could use that entry's target.
+ * Doing this, the above would end up as:
+ *
+ * n1: r=a;       l1: if (!r) goto l4;
+ * n2: r=b;       l2: if (!r) goto l4;
+ * n3: r=c; r=!r; l3: if (r) goto T;
+ * n4: r=g; r=!r; l4: if (r) goto T;
+ * n5: r=d;       l5: if (r) goto T;
+ * n6: r=e;       l6: if (!r) goto F;
+ * n7: r=f; r=!r; l7: if (!r) goto F;
+ * T: return TRUE
+ * F: return FALSE
+ *
+ * In that same pass, if the "when_to_branch" doesn't match, we can simply
+ * go to the program entry after the label. That is, "l2: if (!r) goto l4;"
+ * where "l4: if (r) goto T;", then we can convert l2 to be:
+ * "l2: if (!r) goto n5;".
+ *
+ * This will have the second pass give us:
+ * n1: r=a;       l1: if (!r) goto n5;
+ * n2: r=b;       l2: if (!r) goto n5;
+ * n3: r=c; r=!r; l3: if (r) goto T;
+ * n4: r=g; r=!r; l4: if (r) goto T;
+ * n5: r=d;       l5: if (r) goto T
+ * n6: r=e;       l6: if (!r) goto F;
+ * n7: r=f; r=!r; l7: if (!r) goto F
+ * T: return TRUE
+ * F: return FALSE
+ *
+ * Notice, all the "l#" labels are no longer used, and they can now
+ * be discarded.
+ *
+ * ** THIRD PASS **
+ *
+ * For the third pass we deal with the inverts. As they simply just
+ * make the "when_to_branch" get inverted, a simple loop over the
+ * program to that does: "when_to_branch ^= invert;" will do the
+ * job, leaving us with:
+ * n1: r=a; if (!r) goto n5;
+ * n2: r=b; if (!r) goto n5;
+ * n3: r=c: if (!r) goto T;
+ * n4: r=g; if (!r) goto T;
+ * n5: r=d; if (r) goto T
+ * n6: r=e; if (!r) goto F;
+ * n7: r=f; if (r) goto F
+ * T: return TRUE
+ * F: return FALSE
+ *
+ * As "r = a; if (!r) goto n5;" is obviously the same as
+ * "if (!a) goto n5;" without doing anything we can interperate the
+ * program as:
+ * n1: if (!a) goto n5;
+ * n2: if (!b) goto n5;
+ * n3: if (!c) goto T;
+ * n4: if (!g) goto T;
+ * n5: if (d) goto T
+ * n6: if (!e) goto F;
+ * n7: if (f) goto F
+ * T: return TRUE
+ * F: return FALSE
+ *
+ * Since the inverts are discarded at the end, there's no reason to store
+ * them in the program array (and waste memory). A separate array to hold
+ * the inverts is used and freed at the end.
+ */
+static struct prog_entry *
+predicate_parse(const char *str, int nr_parens, int nr_preds,
+		parse_pred_fn parse_pred, void *data,
+		struct filter_parse_error *pe)
+{
+	struct prog_entry *prog_stack;
+	struct prog_entry *prog;
+	const char *ptr = str;
+	char *inverts = NULL;
+	int *op_stack;
+	int *top;
+	int invert = 0;
+	int ret = -ENOMEM;
+	int len;
+	int N = 0;
+	int i;
+
+	nr_preds += 2; /* For TRUE and FALSE */
+
+	op_stack = kmalloc(sizeof(*op_stack) * nr_parens, GFP_KERNEL);
+	if (!op_stack)
+		return ERR_PTR(-ENOMEM);
+	prog_stack = kmalloc(sizeof(*prog_stack) * nr_preds, GFP_KERNEL);
+	if (!prog_stack) {
+		parse_error(pe, -ENOMEM, 0);
+		goto out_free;
+	}
+	inverts = kmalloc(sizeof(*inverts) * nr_preds, GFP_KERNEL);
+	if (!inverts) {
+		parse_error(pe, -ENOMEM, 0);
+		goto out_free;
+	}
+
+	top = op_stack;
+	prog = prog_stack;
+	*top = 0;
+
+	/* First pass */
+	while (*ptr) {						/* #1 */
+		const char *next = ptr++;
+
+		if (isspace(*next))
+			continue;
+
+		switch (*next) {
+		case '(':					/* #2 */
+			if (top - op_stack > nr_parens)
+				return ERR_PTR(-EINVAL);
+			*(++top) = invert;
+			continue;
+		case '!':					/* #3 */
+			if (!is_not(next))
+				break;
+			invert = !invert;
+			continue;
+		}
+
+		if (N >= nr_preds) {
+			parse_error(pe, FILT_ERR_TOO_MANY_PREDS, next - str);
+			goto out_free;
+		}
+
+		inverts[N] = invert;				/* #4 */
+		prog[N].target = N-1;
+
+		len = parse_pred(next, data, ptr - str, pe, &prog[N].pred);
+		if (len < 0) {
+			ret = len;
+			goto out_free;
+		}
+		ptr = next + len;
+
+		N++;
+
+		ret = -1;
+		while (1) {					/* #5 */
+			next = ptr++;
+			if (isspace(*next))
+				continue;
+
+			switch (*next) {
+			case ')':
+			case '\0':
+				break;
+			case '&':
+			case '|':
+				if (next[1] == next[0]) {
+					ptr++;
+					break;
+				}
+			default:
+				parse_error(pe, FILT_ERR_TOO_MANY_PREDS,
+					    next - str);
+				goto out_free;
+			}
+
+			invert = *top & INVERT;
+
+			if (*top & PROCESS_AND) {		/* #7 */
+				update_preds(prog, N - 1, invert);
+				*top &= ~PROCESS_AND;
+			}
+			if (*next == '&') {			/* #8 */
+				*top |= PROCESS_AND;
+				break;
+			}
+			if (*top & PROCESS_OR) {		/* #9 */
+				update_preds(prog, N - 1, !invert);
+				*top &= ~PROCESS_OR;
+			}
+			if (*next == '|') {			/* #10 */
+				*top |= PROCESS_OR;
+				break;
+			}
+			if (!*next)				/* #11 */
+				goto out;
+
+			if (top == op_stack) {
+				ret = -1;
+				/* Too few '(' */
+				parse_error(pe, FILT_ERR_TOO_MANY_CLOSE, ptr - str);
+				goto out_free;
+			}
+			top--;					/* #12 */
+		}
+	}
+ out:
+	if (top != op_stack) {
+		/* Too many '(' */
+		parse_error(pe, FILT_ERR_TOO_MANY_OPEN, ptr - str);
+		goto out_free;
+	}
+
+	prog[N].pred = NULL;					/* #13 */
+	prog[N].target = 1;		/* TRUE */
+	prog[N+1].pred = NULL;
+	prog[N+1].target = 0;		/* FALSE */
+	prog[N-1].target = N;
+	prog[N-1].when_to_branch = false;
+
+	/* Second Pass */
+	for (i = N-1 ; i--; ) {
+		int target = prog[i].target;
+		if (prog[i].when_to_branch == prog[target].when_to_branch)
+			prog[i].target = prog[target].target;
+	}
+
+	/* Third Pass */
+	for (i = 0; i < N; i++) {
+		invert = inverts[i] ^ prog[i].when_to_branch;
+		prog[i].when_to_branch = invert;
+		/* Make sure the program always moves forward */
+		if (WARN_ON(prog[i].target <= i)) {
+			ret = -EINVAL;
+			goto out_free;
+		}
+	}
+
+	return prog;
+out_free:
+	kfree(op_stack);
+	kfree(prog_stack);
+	kfree(inverts);
+	return ERR_PTR(ret);
+}
+
 #define DEFINE_COMPARISON_PRED(type)					\
 static int filter_pred_LT_##type(struct filter_pred *pred, void *event)	\
 {									\
 	type *addr = (type *)(event + pred->offset);			\
 	type val = (type)pred->val;					\
-	int match = (*addr < val);					\
-	return !!match == !pred->not;					\
+	return *addr < val;						\
 }									\
 static int filter_pred_LE_##type(struct filter_pred *pred, void *event)	\
 {									\
 	type *addr = (type *)(event + pred->offset);			\
 	type val = (type)pred->val;					\
-	int match = (*addr <= val);					\
-	return !!match == !pred->not;					\
+	return *addr <= val;						\
 }									\
 static int filter_pred_GT_##type(struct filter_pred *pred, void *event)	\
 {									\
 	type *addr = (type *)(event + pred->offset);			\
 	type val = (type)pred->val;					\
-	int match = (*addr > val);					\
-	return !!match == !pred->not;					\
+	return *addr > val;					\
 }									\
 static int filter_pred_GE_##type(struct filter_pred *pred, void *event)	\
 {									\
 	type *addr = (type *)(event + pred->offset);			\
 	type val = (type)pred->val;					\
-	int match = (*addr >= val);					\
-	return !!match == !pred->not;					\
+	return *addr >= val;						\
 }									\
 static int filter_pred_BAND_##type(struct filter_pred *pred, void *event) \
 {									\
 	type *addr = (type *)(event + pred->offset);			\
 	type val = (type)pred->val;					\
-	int match = !!(*addr & val);					\
-	return match == !pred->not;					\
+	return !!(*addr & val);						\
 }									\
 static const filter_pred_fn_t pred_funcs_##type[] = {			\
-	filter_pred_LT_##type,						\
 	filter_pred_LE_##type,						\
-	filter_pred_GT_##type,						\
+	filter_pred_LT_##type,						\
 	filter_pred_GE_##type,						\
+	filter_pred_GT_##type,						\
 	filter_pred_BAND_##type,					\
 };
 
-#define PRED_FUNC_START			OP_LT
-
 #define DEFINE_EQUALITY_PRED(size)					\
 static int filter_pred_##size(struct filter_pred *pred, void *event)	\
 {									\
@@ -272,44 +704,36 @@ static int filter_pred_strloc(struct filter_pred *pred, void *event)
 static int filter_pred_cpu(struct filter_pred *pred, void *event)
 {
 	int cpu, cmp;
-	int match = 0;
 
 	cpu = raw_smp_processor_id();
 	cmp = pred->val;
 
 	switch (pred->op) {
 	case OP_EQ:
-		match = cpu == cmp;
-		break;
+		return cpu == cmp;
+	case OP_NE:
+		return cpu != cmp;
 	case OP_LT:
-		match = cpu < cmp;
-		break;
+		return cpu < cmp;
 	case OP_LE:
-		match = cpu <= cmp;
-		break;
+		return cpu <= cmp;
 	case OP_GT:
-		match = cpu > cmp;
-		break;
+		return cpu > cmp;
 	case OP_GE:
-		match = cpu >= cmp;
-		break;
+		return cpu >= cmp;
 	default:
-		break;
+		return 0;
 	}
-
-	return !!match == !pred->not;
 }
 
 /* Filter predicate for COMM. */
 static int filter_pred_comm(struct filter_pred *pred, void *event)
 {
-	int cmp, match;
+	int cmp;
 
 	cmp = pred->regex.match(current->comm, &pred->regex,
-				pred->regex.field_len);
-	match = cmp ^ pred->not;
-
-	return match;
+				TASK_COMM_LEN);
+	return cmp ^ pred->not;
 }
 
 static int filter_pred_none(struct filter_pred *pred, void *event)
@@ -366,6 +790,7 @@ static int regex_match_glob(char *str, struct regex *r, int len __maybe_unused)
 		return 1;
 	return 0;
 }
+
 /**
  * filter_parse_regex - parse a basic regex
  * @buff:   the raw regex
@@ -426,10 +851,9 @@ static void filter_build_regex(struct filter_pred *pred)
 	struct regex *r = &pred->regex;
 	char *search;
 	enum regex_type type = MATCH_FULL;
-	int not = 0;
 
 	if (pred->op == OP_GLOB) {
-		type = filter_parse_regex(r->pattern, r->len, &search, &not);
+		type = filter_parse_regex(r->pattern, r->len, &search, &pred->not);
 		r->len = strlen(search);
 		memmove(r->pattern, search, r->len+1);
 	}
@@ -451,210 +875,32 @@ static void filter_build_regex(struct filter_pred *pred)
 		r->match = regex_match_glob;
 		break;
 	}
-
-	pred->not ^= not;
-}
-
-enum move_type {
-	MOVE_DOWN,
-	MOVE_UP_FROM_LEFT,
-	MOVE_UP_FROM_RIGHT
-};
-
-static struct filter_pred *
-get_pred_parent(struct filter_pred *pred, struct filter_pred *preds,
-		int index, enum move_type *move)
-{
-	if (pred->parent & FILTER_PRED_IS_RIGHT)
-		*move = MOVE_UP_FROM_RIGHT;
-	else
-		*move = MOVE_UP_FROM_LEFT;
-	pred = &preds[pred->parent & ~FILTER_PRED_IS_RIGHT];
-
-	return pred;
-}
-
-enum walk_return {
-	WALK_PRED_ABORT,
-	WALK_PRED_PARENT,
-	WALK_PRED_DEFAULT,
-};
-
-typedef int (*filter_pred_walkcb_t) (enum move_type move,
-				     struct filter_pred *pred,
-				     int *err, void *data);
-
-static int walk_pred_tree(struct filter_pred *preds,
-			  struct filter_pred *root,
-			  filter_pred_walkcb_t cb, void *data)
-{
-	struct filter_pred *pred = root;
-	enum move_type move = MOVE_DOWN;
-	int done = 0;
-
-	if  (!preds)
-		return -EINVAL;
-
-	do {
-		int err = 0, ret;
-
-		ret = cb(move, pred, &err, data);
-		if (ret == WALK_PRED_ABORT)
-			return err;
-		if (ret == WALK_PRED_PARENT)
-			goto get_parent;
-
-		switch (move) {
-		case MOVE_DOWN:
-			if (pred->left != FILTER_PRED_INVALID) {
-				pred = &preds[pred->left];
-				continue;
-			}
-			goto get_parent;
-		case MOVE_UP_FROM_LEFT:
-			pred = &preds[pred->right];
-			move = MOVE_DOWN;
-			continue;
-		case MOVE_UP_FROM_RIGHT:
- get_parent:
-			if (pred == root)
-				break;
-			pred = get_pred_parent(pred, preds,
-					       pred->parent,
-					       &move);
-			continue;
-		}
-		done = 1;
-	} while (!done);
-
-	/* We are fine. */
-	return 0;
-}
-
-/*
- * A series of AND or ORs where found together. Instead of
- * climbing up and down the tree branches, an array of the
- * ops were made in order of checks. We can just move across
- * the array and short circuit if needed.
- */
-static int process_ops(struct filter_pred *preds,
-		       struct filter_pred *op, void *rec)
-{
-	struct filter_pred *pred;
-	int match = 0;
-	int type;
-	int i;
-
-	/*
-	 * Micro-optimization: We set type to true if op
-	 * is an OR and false otherwise (AND). Then we
-	 * just need to test if the match is equal to
-	 * the type, and if it is, we can short circuit the
-	 * rest of the checks:
-	 *
-	 * if ((match && op->op == OP_OR) ||
-	 *     (!match && op->op == OP_AND))
-	 *	  return match;
-	 */
-	type = op->op == OP_OR;
-
-	for (i = 0; i < op->val; i++) {
-		pred = &preds[op->ops[i]];
-		if (!WARN_ON_ONCE(!pred->fn))
-			match = pred->fn(pred, rec);
-		if (!!match == type)
-			break;
-	}
-	/* If not of not match is equal to not of not, then it is a match */
-	return !!match == !op->not;
-}
-
-struct filter_match_preds_data {
-	struct filter_pred *preds;
-	int match;
-	void *rec;
-};
-
-static int filter_match_preds_cb(enum move_type move, struct filter_pred *pred,
-				 int *err, void *data)
-{
-	struct filter_match_preds_data *d = data;
-
-	*err = 0;
-	switch (move) {
-	case MOVE_DOWN:
-		/* only AND and OR have children */
-		if (pred->left != FILTER_PRED_INVALID) {
-			/* If ops is set, then it was folded. */
-			if (!pred->ops)
-				return WALK_PRED_DEFAULT;
-			/* We can treat folded ops as a leaf node */
-			d->match = process_ops(d->preds, pred, d->rec);
-		} else {
-			if (!WARN_ON_ONCE(!pred->fn))
-				d->match = pred->fn(pred, d->rec);
-		}
-
-		return WALK_PRED_PARENT;
-	case MOVE_UP_FROM_LEFT:
-		/*
-		 * Check for short circuits.
-		 *
-		 * Optimization: !!match == (pred->op == OP_OR)
-		 *   is the same as:
-		 * if ((match && pred->op == OP_OR) ||
-		 *     (!match && pred->op == OP_AND))
-		 */
-		if (!!d->match == (pred->op == OP_OR))
-			return WALK_PRED_PARENT;
-		break;
-	case MOVE_UP_FROM_RIGHT:
-		break;
-	}
-
-	return WALK_PRED_DEFAULT;
 }
 
 /* return 1 if event matches, 0 otherwise (discard) */
 int filter_match_preds(struct event_filter *filter, void *rec)
 {
-	struct filter_pred *preds;
-	struct filter_pred *root;
-	struct filter_match_preds_data data = {
-		/* match is currently meaningless */
-		.match = -1,
-		.rec   = rec,
-	};
-	int n_preds, ret;
+	struct prog_entry *prog;
+	int i;
 
 	/* no filter is considered a match */
 	if (!filter)
 		return 1;
 
-	n_preds = filter->n_preds;
-	if (!n_preds)
+	prog = rcu_dereference_sched(filter->prog);
+	if (!prog)
 		return 1;
 
-	/*
-	 * n_preds, root and filter->preds are protect with preemption disabled.
-	 */
-	root = rcu_dereference_sched(filter->root);
-	if (!root)
-		return 1;
-
-	data.preds = preds = rcu_dereference_sched(filter->preds);
-	ret = walk_pred_tree(preds, root, filter_match_preds_cb, &data);
-	WARN_ON(ret);
-	return data.match;
+	for (i = 0; prog[i].pred; i++) {
+		struct filter_pred *pred = prog[i].pred;
+		int match = pred->fn(pred, rec);
+		if (match == prog[i].when_to_branch)
+			i = prog[i].target;
+	}
+	return prog[i].target;
 }
 EXPORT_SYMBOL_GPL(filter_match_preds);
 
-static void parse_error(struct filter_parse_state *ps, int err, int pos)
-{
-	ps->lasterr = err;
-	ps->lasterr_pos = pos;
-}
-
 static void remove_filter_string(struct event_filter *filter)
 {
 	if (!filter)
@@ -664,57 +910,44 @@ static void remove_filter_string(struct event_filter *filter)
 	filter->filter_string = NULL;
 }
 
-static int replace_filter_string(struct event_filter *filter,
-				 char *filter_string)
-{
-	kfree(filter->filter_string);
-	filter->filter_string = kstrdup(filter_string, GFP_KERNEL);
-	if (!filter->filter_string)
-		return -ENOMEM;
-
-	return 0;
-}
-
-static int append_filter_string(struct event_filter *filter,
-				char *string)
-{
-	int newlen;
-	char *new_filter_string;
-
-	BUG_ON(!filter->filter_string);
-	newlen = strlen(filter->filter_string) + strlen(string) + 1;
-	new_filter_string = kmalloc(newlen, GFP_KERNEL);
-	if (!new_filter_string)
-		return -ENOMEM;
-
-	strcpy(new_filter_string, filter->filter_string);
-	strcat(new_filter_string, string);
-	kfree(filter->filter_string);
-	filter->filter_string = new_filter_string;
-
-	return 0;
-}
-
-static void append_filter_err(struct filter_parse_state *ps,
+static void append_filter_err(struct filter_parse_error *pe,
 			      struct event_filter *filter)
 {
-	int pos = ps->lasterr_pos;
-	char *buf, *pbuf;
+	struct trace_seq *s;
+	int pos = pe->lasterr_pos;
+	char *buf;
+	int len;
+
+	if (WARN_ON(!filter->filter_string))
+		return;
 
-	buf = (char *)__get_free_page(GFP_KERNEL);
-	if (!buf)
+	s = kmalloc(sizeof(*s), GFP_KERNEL);
+	if (!s)
 		return;
+	trace_seq_init(s);
 
-	append_filter_string(filter, "\n");
-	memset(buf, ' ', PAGE_SIZE);
-	if (pos > PAGE_SIZE - 128)
-		pos = 0;
-	buf[pos] = '^';
-	pbuf = &buf[pos] + 1;
+	len = strlen(filter->filter_string);
+	if (pos > len)
+		pos = len;
 
-	sprintf(pbuf, "\nparse_error: %s\n", err_text[ps->lasterr]);
-	append_filter_string(filter, buf);
-	free_page((unsigned long) buf);
+	/* indexing is off by one */
+	if (pos)
+		pos++;
+
+	trace_seq_puts(s, filter->filter_string);
+	if (pe->lasterr > 0) {
+		trace_seq_printf(s, "\n%*s", pos, "^");
+		trace_seq_printf(s, "\nparse_error: %s\n", err_text[pe->lasterr]);
+	} else {
+		trace_seq_printf(s, "\nError: (%d)\n", pe->lasterr);
+	}
+	trace_seq_putc(s, 0);
+	buf = kmemdup_nul(s->buffer, s->seq.len, GFP_KERNEL);
+	if (buf) {
+		kfree(filter->filter_string);
+		filter->filter_string = buf;
+	}
+	kfree(s);
 }
 
 static inline struct event_filter *event_filter(struct trace_event_file *file)
@@ -747,108 +980,18 @@ void print_subsystem_event_filter(struct event_subsystem *system,
 	mutex_unlock(&event_mutex);
 }
 
-static int __alloc_pred_stack(struct pred_stack *stack, int n_preds)
-{
-	stack->preds = kcalloc(n_preds + 1, sizeof(*stack->preds), GFP_KERNEL);
-	if (!stack->preds)
-		return -ENOMEM;
-	stack->index = n_preds;
-	return 0;
-}
-
-static void __free_pred_stack(struct pred_stack *stack)
-{
-	kfree(stack->preds);
-	stack->index = 0;
-}
-
-static int __push_pred_stack(struct pred_stack *stack,
-			     struct filter_pred *pred)
-{
-	int index = stack->index;
-
-	if (WARN_ON(index == 0))
-		return -ENOSPC;
-
-	stack->preds[--index] = pred;
-	stack->index = index;
-	return 0;
-}
-
-static struct filter_pred *
-__pop_pred_stack(struct pred_stack *stack)
-{
-	struct filter_pred *pred;
-	int index = stack->index;
-
-	pred = stack->preds[index++];
-	if (!pred)
-		return NULL;
-
-	stack->index = index;
-	return pred;
-}
-
-static int filter_set_pred(struct event_filter *filter,
-			   int idx,
-			   struct pred_stack *stack,
-			   struct filter_pred *src)
-{
-	struct filter_pred *dest = &filter->preds[idx];
-	struct filter_pred *left;
-	struct filter_pred *right;
-
-	*dest = *src;
-	dest->index = idx;
-
-	if (dest->op == OP_OR || dest->op == OP_AND) {
-		right = __pop_pred_stack(stack);
-		left = __pop_pred_stack(stack);
-		if (!left || !right)
-			return -EINVAL;
-		/*
-		 * If both children can be folded
-		 * and they are the same op as this op or a leaf,
-		 * then this op can be folded.
-		 */
-		if (left->index & FILTER_PRED_FOLD &&
-		    ((left->op == dest->op && !left->not) ||
-		     left->left == FILTER_PRED_INVALID) &&
-		    right->index & FILTER_PRED_FOLD &&
-		    ((right->op == dest->op && !right->not) ||
-		     right->left == FILTER_PRED_INVALID))
-			dest->index |= FILTER_PRED_FOLD;
-
-		dest->left = left->index & ~FILTER_PRED_FOLD;
-		dest->right = right->index & ~FILTER_PRED_FOLD;
-		left->parent = dest->index & ~FILTER_PRED_FOLD;
-		right->parent = dest->index | FILTER_PRED_IS_RIGHT;
-	} else {
-		/*
-		 * Make dest->left invalid to be used as a quick
-		 * way to know this is a leaf node.
-		 */
-		dest->left = FILTER_PRED_INVALID;
-
-		/* All leafs allow folding the parent ops. */
-		dest->index |= FILTER_PRED_FOLD;
-	}
-
-	return __push_pred_stack(stack, dest);
-}
-
-static void __free_preds(struct event_filter *filter)
+static void free_prog(struct event_filter *filter)
 {
+	struct prog_entry *prog;
 	int i;
 
-	if (filter->preds) {
-		for (i = 0; i < filter->n_preds; i++)
-			kfree(filter->preds[i].ops);
-		kfree(filter->preds);
-		filter->preds = NULL;
-	}
-	filter->a_preds = 0;
-	filter->n_preds = 0;
+	prog = rcu_access_pointer(filter->prog);
+	if (!prog)
+		return;
+
+	for (i = 0; prog[i].pred; i++)
+		kfree(prog[i].pred);
+	kfree(prog);
 }
 
 static void filter_disable(struct trace_event_file *file)
@@ -866,7 +1009,7 @@ static void __free_filter(struct event_filter *filter)
 	if (!filter)
 		return;
 
-	__free_preds(filter);
+	free_prog(filter);
 	kfree(filter->filter_string);
 	kfree(filter);
 }
@@ -876,38 +1019,6 @@ void free_event_filter(struct event_filter *filter)
 	__free_filter(filter);
 }
 
-static struct event_filter *__alloc_filter(void)
-{
-	struct event_filter *filter;
-
-	filter = kzalloc(sizeof(*filter), GFP_KERNEL);
-	return filter;
-}
-
-static int __alloc_preds(struct event_filter *filter, int n_preds)
-{
-	struct filter_pred *pred;
-	int i;
-
-	if (filter->preds)
-		__free_preds(filter);
-
-	filter->preds = kcalloc(n_preds, sizeof(*filter->preds), GFP_KERNEL);
-
-	if (!filter->preds)
-		return -ENOMEM;
-
-	filter->a_preds = n_preds;
-	filter->n_preds = 0;
-
-	for (i = 0; i < n_preds; i++) {
-		pred = &filter->preds[i];
-		pred->fn = filter_pred_none;
-	}
-
-	return 0;
-}
-
 static inline void __remove_filter(struct trace_event_file *file)
 {
 	filter_disable(file);
@@ -944,27 +1055,6 @@ static void filter_free_subsystem_filters(struct trace_subsystem_dir *dir,
 	}
 }
 
-static int filter_add_pred(struct filter_parse_state *ps,
-			   struct event_filter *filter,
-			   struct filter_pred *pred,
-			   struct pred_stack *stack)
-{
-	int err;
-
-	if (WARN_ON(filter->n_preds == filter->a_preds)) {
-		parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0);
-		return -ENOSPC;
-	}
-
-	err = filter_set_pred(filter, filter->n_preds, stack, pred);
-	if (err)
-		return err;
-
-	filter->n_preds++;
-
-	return 0;
-}
-
 int filter_assign_type(const char *type)
 {
 	if (strstr(type, "__data_loc") && strstr(type, "char"))
@@ -976,761 +1066,449 @@ int filter_assign_type(const char *type)
 	return FILTER_OTHER;
 }
 
-static bool is_legal_op(struct ftrace_event_field *field, enum filter_op_ids op)
-{
-	if (is_string_field(field) &&
-	    (op != OP_EQ && op != OP_NE && op != OP_GLOB))
-		return false;
-	if (!is_string_field(field) && op == OP_GLOB)
-		return false;
-
-	return true;
-}
-
 static filter_pred_fn_t select_comparison_fn(enum filter_op_ids op,
 					    int field_size, int field_is_signed)
 {
 	filter_pred_fn_t fn = NULL;
+	int pred_func_index = -1;
+
+	switch (op) {
+	case OP_EQ:
+	case OP_NE:
+		break;
+	default:
+		if (WARN_ON_ONCE(op < PRED_FUNC_START))
+			return NULL;
+		pred_func_index = op - PRED_FUNC_START;
+		if (WARN_ON_ONCE(pred_func_index > PRED_FUNC_MAX))
+			return NULL;
+	}
 
 	switch (field_size) {
 	case 8:
-		if (op == OP_EQ || op == OP_NE)
+		if (pred_func_index < 0)
 			fn = filter_pred_64;
 		else if (field_is_signed)
-			fn = pred_funcs_s64[op - PRED_FUNC_START];
+			fn = pred_funcs_s64[pred_func_index];
 		else
-			fn = pred_funcs_u64[op - PRED_FUNC_START];
+			fn = pred_funcs_u64[pred_func_index];
 		break;
 	case 4:
-		if (op == OP_EQ || op == OP_NE)
+		if (pred_func_index < 0)
 			fn = filter_pred_32;
 		else if (field_is_signed)
-			fn = pred_funcs_s32[op - PRED_FUNC_START];
+			fn = pred_funcs_s32[pred_func_index];
 		else
-			fn = pred_funcs_u32[op - PRED_FUNC_START];
+			fn = pred_funcs_u32[pred_func_index];
 		break;
 	case 2:
-		if (op == OP_EQ || op == OP_NE)
+		if (pred_func_index < 0)
 			fn = filter_pred_16;
 		else if (field_is_signed)
-			fn = pred_funcs_s16[op - PRED_FUNC_START];
+			fn = pred_funcs_s16[pred_func_index];
 		else
-			fn = pred_funcs_u16[op - PRED_FUNC_START];
+			fn = pred_funcs_u16[pred_func_index];
 		break;
 	case 1:
-		if (op == OP_EQ || op == OP_NE)
+		if (pred_func_index < 0)
 			fn = filter_pred_8;
 		else if (field_is_signed)
-			fn = pred_funcs_s8[op - PRED_FUNC_START];
+			fn = pred_funcs_s8[pred_func_index];
 		else
-			fn = pred_funcs_u8[op - PRED_FUNC_START];
+			fn = pred_funcs_u8[pred_func_index];
 		break;
 	}
 
 	return fn;
 }
 
-static int init_pred(struct filter_parse_state *ps,
-		     struct ftrace_event_field *field,
-		     struct filter_pred *pred)
-
+/* Called when a predicate is encountered by predicate_parse() */
+static int parse_pred(const char *str, void *data,
+		      int pos, struct filter_parse_error *pe,
+		      struct filter_pred **pred_ptr)
 {
-	filter_pred_fn_t fn = filter_pred_none;
-	unsigned long long val;
+	struct trace_event_call *call = data;
+	struct ftrace_event_field *field;
+	struct filter_pred *pred = NULL;
+	char num_buf[24];	/* Big enough to hold an address */
+	char *field_name;
+	char q;
+	u64 val;
+	int len;
 	int ret;
+	int op;
+	int s;
+	int i = 0;
 
-	pred->offset = field->offset;
-
-	if (!is_legal_op(field, pred->op)) {
-		parse_error(ps, FILT_ERR_ILLEGAL_FIELD_OP, 0);
-		return -EINVAL;
-	}
-
-	if (field->filter_type == FILTER_COMM) {
-		filter_build_regex(pred);
-		fn = filter_pred_comm;
-		pred->regex.field_len = TASK_COMM_LEN;
-	} else if (is_string_field(field)) {
-		filter_build_regex(pred);
-
-		if (field->filter_type == FILTER_STATIC_STRING) {
-			fn = filter_pred_string;
-			pred->regex.field_len = field->size;
-		} else if (field->filter_type == FILTER_DYN_STRING)
-			fn = filter_pred_strloc;
-		else
-			fn = filter_pred_pchar;
-	} else if (is_function_field(field)) {
-		if (strcmp(field->name, "ip")) {
-			parse_error(ps, FILT_ERR_IP_FIELD_ONLY, 0);
-			return -EINVAL;
-		}
-	} else {
-		if (field->is_signed)
-			ret = kstrtoll(pred->regex.pattern, 0, &val);
-		else
-			ret = kstrtoull(pred->regex.pattern, 0, &val);
-		if (ret) {
-			parse_error(ps, FILT_ERR_ILLEGAL_INTVAL, 0);
-			return -EINVAL;
-		}
-		pred->val = val;
-
-		if (field->filter_type == FILTER_CPU)
-			fn = filter_pred_cpu;
-		else
-			fn = select_comparison_fn(pred->op, field->size,
-					  field->is_signed);
-		if (!fn) {
-			parse_error(ps, FILT_ERR_INVALID_OP, 0);
-			return -EINVAL;
-		}
-	}
-
-	if (pred->op == OP_NE)
-		pred->not ^= 1;
-
-	pred->fn = fn;
-	return 0;
-}
-
-static void parse_init(struct filter_parse_state *ps,
-		       struct filter_op *ops,
-		       char *infix_string)
-{
-	memset(ps, '\0', sizeof(*ps));
-
-	ps->infix.string = infix_string;
-	ps->infix.cnt = strlen(infix_string);
-	ps->ops = ops;
-
-	INIT_LIST_HEAD(&ps->opstack);
-	INIT_LIST_HEAD(&ps->postfix);
-}
-
-static char infix_next(struct filter_parse_state *ps)
-{
-	if (!ps->infix.cnt)
-		return 0;
-
-	ps->infix.cnt--;
-
-	return ps->infix.string[ps->infix.tail++];
-}
+	/* First find the field to associate to */
+	while (isspace(str[i]))
+		i++;
+	s = i;
 
-static char infix_peek(struct filter_parse_state *ps)
-{
-	if (ps->infix.tail == strlen(ps->infix.string))
-		return 0;
+	while (isalnum(str[i]) || str[i] == '_')
+		i++;
 
-	return ps->infix.string[ps->infix.tail];
-}
+	len = i - s;
 
-static void infix_advance(struct filter_parse_state *ps)
-{
-	if (!ps->infix.cnt)
-		return;
+	if (!len)
+		return -1;
 
-	ps->infix.cnt--;
-	ps->infix.tail++;
-}
+	field_name = kmemdup_nul(str + s, len, GFP_KERNEL);
+	if (!field_name)
+		return -ENOMEM;
 
-static inline int is_precedence_lower(struct filter_parse_state *ps,
-				      int a, int b)
-{
-	return ps->ops[a].precedence < ps->ops[b].precedence;
-}
+	/* Make sure that the field exists */
 
-static inline int is_op_char(struct filter_parse_state *ps, char c)
-{
-	int i;
-
-	for (i = 0; strcmp(ps->ops[i].string, "OP_NONE"); i++) {
-		if (ps->ops[i].string[0] == c)
-			return 1;
+	field = trace_find_event_field(call, field_name);
+	kfree(field_name);
+	if (!field) {
+		parse_error(pe, FILT_ERR_FIELD_NOT_FOUND, pos + i);
+		return -EINVAL;
 	}
 
-	return 0;
-}
+	while (isspace(str[i]))
+		i++;
 
-static int infix_get_op(struct filter_parse_state *ps, char firstc)
-{
-	char nextc = infix_peek(ps);
-	char opstr[3];
-	int i;
-
-	opstr[0] = firstc;
-	opstr[1] = nextc;
-	opstr[2] = '\0';
-
-	for (i = 0; strcmp(ps->ops[i].string, "OP_NONE"); i++) {
-		if (!strcmp(opstr, ps->ops[i].string)) {
-			infix_advance(ps);
-			return ps->ops[i].id;
-		}
+	/* Make sure this op is supported */
+	for (op = 0; ops[op]; op++) {
+		/* This is why '<=' must come before '<' in ops[] */
+		if (strncmp(str + i, ops[op], strlen(ops[op])) == 0)
+			break;
 	}
 
-	opstr[1] = '\0';
-
-	for (i = 0; strcmp(ps->ops[i].string, "OP_NONE"); i++) {
-		if (!strcmp(opstr, ps->ops[i].string))
-			return ps->ops[i].id;
+	if (!ops[op]) {
+		parse_error(pe, FILT_ERR_INVALID_OP, pos + i);
+		goto err_free;
 	}
 
-	return OP_NONE;
-}
-
-static inline void clear_operand_string(struct filter_parse_state *ps)
-{
-	memset(ps->operand.string, '\0', MAX_FILTER_STR_VAL);
-	ps->operand.tail = 0;
-}
-
-static inline int append_operand_char(struct filter_parse_state *ps, char c)
-{
-	if (ps->operand.tail == MAX_FILTER_STR_VAL - 1)
-		return -EINVAL;
-
-	ps->operand.string[ps->operand.tail++] = c;
+	i += strlen(ops[op]);
 
-	return 0;
-}
+	while (isspace(str[i]))
+		i++;
 
-static int filter_opstack_push(struct filter_parse_state *ps,
-			       enum filter_op_ids op)
-{
-	struct opstack_op *opstack_op;
+	s = i;
 
-	opstack_op = kmalloc(sizeof(*opstack_op), GFP_KERNEL);
-	if (!opstack_op)
+	pred = kzalloc(sizeof(*pred), GFP_KERNEL);
+	if (!pred)
 		return -ENOMEM;
 
-	opstack_op->op = op;
-	list_add(&opstack_op->list, &ps->opstack);
+	pred->field = field;
+	pred->offset = field->offset;
+	pred->op = op;
 
-	return 0;
-}
+	if (ftrace_event_is_function(call)) {
+		/*
+		 * Perf does things different with function events.
+		 * It only allows an "ip" field, and expects a string.
+		 * But the string does not need to be surrounded by quotes.
+		 * If it is a string, the assigned function as a nop,
+		 * (perf doesn't use it) and grab everything.
+		 */
+		if (strcmp(field->name, "ip") != 0) {
+			 parse_error(pe, FILT_ERR_IP_FIELD_ONLY, pos + i);
+			 goto err_free;
+		 }
+		 pred->fn = filter_pred_none;
+
+		 /*
+		  * Quotes are not required, but if they exist then we need
+		  * to read them till we hit a matching one.
+		  */
+		 if (str[i] == '\'' || str[i] == '"')
+			 q = str[i];
+		 else
+			 q = 0;
+
+		 for (i++; str[i]; i++) {
+			 if (q && str[i] == q)
+				 break;
+			 if (!q && (str[i] == ')' || str[i] == '&' ||
+				    str[i] == '|'))
+				 break;
+		 }
+		 /* Skip quotes */
+		 if (q)
+			 s++;
+		len = i - s;
+		if (len >= MAX_FILTER_STR_VAL) {
+			parse_error(pe, FILT_ERR_OPERAND_TOO_LONG, pos + i);
+			goto err_free;
+		}
 
-static int filter_opstack_empty(struct filter_parse_state *ps)
-{
-	return list_empty(&ps->opstack);
-}
+		pred->regex.len = len;
+		strncpy(pred->regex.pattern, str + s, len);
+		pred->regex.pattern[len] = 0;
+
+	/* This is either a string, or an integer */
+	} else if (str[i] == '\'' || str[i] == '"') {
+		char q = str[i];
+
+		/* Make sure the op is OK for strings */
+		switch (op) {
+		case OP_NE:
+			pred->not = 1;
+			/* Fall through */
+		case OP_GLOB:
+		case OP_EQ:
+			break;
+		default:
+			parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i);
+			goto err_free;
+		}
 
-static int filter_opstack_top(struct filter_parse_state *ps)
-{
-	struct opstack_op *opstack_op;
+		/* Make sure the field is OK for strings */
+		if (!is_string_field(field)) {
+			parse_error(pe, FILT_ERR_EXPECT_DIGIT, pos + i);
+			goto err_free;
+		}
 
-	if (filter_opstack_empty(ps))
-		return OP_NONE;
+		for (i++; str[i]; i++) {
+			if (str[i] == q)
+				break;
+		}
+		if (!str[i]) {
+			parse_error(pe, FILT_ERR_MISSING_QUOTE, pos + i);
+			goto err_free;
+		}
 
-	opstack_op = list_first_entry(&ps->opstack, struct opstack_op, list);
+		/* Skip quotes */
+		s++;
+		len = i - s;
+		if (len >= MAX_FILTER_STR_VAL) {
+			parse_error(pe, FILT_ERR_OPERAND_TOO_LONG, pos + i);
+			goto err_free;
+		}
 
-	return opstack_op->op;
-}
+		pred->regex.len = len;
+		strncpy(pred->regex.pattern, str + s, len);
+		pred->regex.pattern[len] = 0;
 
-static int filter_opstack_pop(struct filter_parse_state *ps)
-{
-	struct opstack_op *opstack_op;
-	enum filter_op_ids op;
+		filter_build_regex(pred);
 
-	if (filter_opstack_empty(ps))
-		return OP_NONE;
+		if (field->filter_type == FILTER_COMM) {
+			pred->fn = filter_pred_comm;
 
-	opstack_op = list_first_entry(&ps->opstack, struct opstack_op, list);
-	op = opstack_op->op;
-	list_del(&opstack_op->list);
+		} else if (field->filter_type == FILTER_STATIC_STRING) {
+			pred->fn = filter_pred_string;
+			pred->regex.field_len = field->size;
 
-	kfree(opstack_op);
+		} else if (field->filter_type == FILTER_DYN_STRING)
+			pred->fn = filter_pred_strloc;
+		else
+			pred->fn = filter_pred_pchar;
+		/* go past the last quote */
+		i++;
 
-	return op;
-}
+	} else if (isdigit(str[i])) {
 
-static void filter_opstack_clear(struct filter_parse_state *ps)
-{
-	while (!filter_opstack_empty(ps))
-		filter_opstack_pop(ps);
-}
-
-static char *curr_operand(struct filter_parse_state *ps)
-{
-	return ps->operand.string;
-}
+		/* Make sure the field is not a string */
+		if (is_string_field(field)) {
+			parse_error(pe, FILT_ERR_EXPECT_STRING, pos + i);
+			goto err_free;
+		}
 
-static int postfix_append_operand(struct filter_parse_state *ps, char *operand)
-{
-	struct postfix_elt *elt;
+		if (op == OP_GLOB) {
+			parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i);
+			goto err_free;
+		}
 
-	elt = kmalloc(sizeof(*elt), GFP_KERNEL);
-	if (!elt)
-		return -ENOMEM;
+		/* We allow 0xDEADBEEF */
+		while (isalnum(str[i]))
+			i++;
 
-	elt->op = OP_NONE;
-	elt->operand = kstrdup(operand, GFP_KERNEL);
-	if (!elt->operand) {
-		kfree(elt);
-		return -ENOMEM;
-	}
+		len = i - s;
+		/* 0xfeedfacedeadbeef is 18 chars max */
+		if (len >= sizeof(num_buf)) {
+			parse_error(pe, FILT_ERR_OPERAND_TOO_LONG, pos + i);
+			goto err_free;
+		}
 
-	list_add_tail(&elt->list, &ps->postfix);
+		strncpy(num_buf, str + s, len);
+		num_buf[len] = 0;
 
-	return 0;
-}
+		/* Make sure it is a value */
+		if (field->is_signed)
+			ret = kstrtoll(num_buf, 0, &val);
+		else
+			ret = kstrtoull(num_buf, 0, &val);
+		if (ret) {
+			parse_error(pe, FILT_ERR_ILLEGAL_INTVAL, pos + s);
+			goto err_free;
+		}
 
-static int postfix_append_op(struct filter_parse_state *ps, enum filter_op_ids op)
-{
-	struct postfix_elt *elt;
+		pred->val = val;
 
-	elt = kmalloc(sizeof(*elt), GFP_KERNEL);
-	if (!elt)
-		return -ENOMEM;
+		if (field->filter_type == FILTER_CPU)
+			pred->fn = filter_pred_cpu;
+		else {
+			pred->fn = select_comparison_fn(pred->op, field->size,
+							field->is_signed);
+			if (pred->op == OP_NE)
+				pred->not = 1;
+		}
 
-	elt->op = op;
-	elt->operand = NULL;
+	} else {
+		parse_error(pe, FILT_ERR_INVALID_VALUE, pos + i);
+		goto err_free;
+	}
 
-	list_add_tail(&elt->list, &ps->postfix);
+	*pred_ptr = pred;
+	return i;
 
-	return 0;
+err_free:
+	kfree(pred);
+	return -EINVAL;
 }
 
-static void postfix_clear(struct filter_parse_state *ps)
-{
-	struct postfix_elt *elt;
+enum {
+	TOO_MANY_CLOSE		= -1,
+	TOO_MANY_OPEN		= -2,
+	MISSING_QUOTE		= -3,
+};
 
-	while (!list_empty(&ps->postfix)) {
-		elt = list_first_entry(&ps->postfix, struct postfix_elt, list);
-		list_del(&elt->list);
-		kfree(elt->operand);
-		kfree(elt);
-	}
-}
+/*
+ * Read the filter string once to calculate the number of predicates
+ * as well as how deep the parentheses go.
+ *
+ * Returns:
+ *   0 - everything is fine (err is undefined)
+ *  -1 - too many ')'
+ *  -2 - too many '('
+ *  -3 - No matching quote
+ */
+static int calc_stack(const char *str, int *parens, int *preds, int *err)
+{
+	bool is_pred = false;
+	int nr_preds = 0;
+	int open = 1; /* Count the expression as "(E)" */
+	int last_quote = 0;
+	int max_open = 1;
+	int quote = 0;
+	int i;
 
-static int filter_parse(struct filter_parse_state *ps)
-{
-	enum filter_op_ids op, top_op;
-	int in_string = 0;
-	char ch;
+	*err = 0;
 
-	while ((ch = infix_next(ps))) {
-		if (ch == '"') {
-			in_string ^= 1;
+	for (i = 0; str[i]; i++) {
+		if (isspace(str[i]))
 			continue;
-		}
-
-		if (in_string)
-			goto parse_operand;
-
-		if (isspace(ch))
+		if (quote) {
+			if (str[i] == quote)
+			       quote = 0;
 			continue;
+		}
 
-		if (is_op_char(ps, ch)) {
-			op = infix_get_op(ps, ch);
-			if (op == OP_NONE) {
-				parse_error(ps, FILT_ERR_INVALID_OP, 0);
-				return -EINVAL;
-			}
-
-			if (strlen(curr_operand(ps))) {
-				postfix_append_operand(ps, curr_operand(ps));
-				clear_operand_string(ps);
-			}
-
-			while (!filter_opstack_empty(ps)) {
-				top_op = filter_opstack_top(ps);
-				if (!is_precedence_lower(ps, top_op, op)) {
-					top_op = filter_opstack_pop(ps);
-					postfix_append_op(ps, top_op);
-					continue;
-				}
+		switch (str[i]) {
+		case '\'':
+		case '"':
+			quote = str[i];
+			last_quote = i;
+			break;
+		case '|':
+		case '&':
+			if (str[i+1] != str[i])
 				break;
-			}
-
-			filter_opstack_push(ps, op);
+			is_pred = false;
 			continue;
-		}
-
-		if (ch == '(') {
-			filter_opstack_push(ps, OP_OPEN_PAREN);
+		case '(':
+			is_pred = false;
+			open++;
+			if (open > max_open)
+				max_open = open;
 			continue;
-		}
-
-		if (ch == ')') {
-			if (strlen(curr_operand(ps))) {
-				postfix_append_operand(ps, curr_operand(ps));
-				clear_operand_string(ps);
-			}
-
-			top_op = filter_opstack_pop(ps);
-			while (top_op != OP_NONE) {
-				if (top_op == OP_OPEN_PAREN)
-					break;
-				postfix_append_op(ps, top_op);
-				top_op = filter_opstack_pop(ps);
-			}
-			if (top_op == OP_NONE) {
-				parse_error(ps, FILT_ERR_UNBALANCED_PAREN, 0);
-				return -EINVAL;
+		case ')':
+			is_pred = false;
+			if (open == 1) {
+				*err = i;
+				return TOO_MANY_CLOSE;
 			}
+			open--;
 			continue;
 		}
-parse_operand:
-		if (append_operand_char(ps, ch)) {
-			parse_error(ps, FILT_ERR_OPERAND_TOO_LONG, 0);
-			return -EINVAL;
+		if (!is_pred) {
+			nr_preds++;
+			is_pred = true;
 		}
 	}
 
-	if (strlen(curr_operand(ps)))
-		postfix_append_operand(ps, curr_operand(ps));
-
-	while (!filter_opstack_empty(ps)) {
-		top_op = filter_opstack_pop(ps);
-		if (top_op == OP_NONE)
-			break;
-		if (top_op == OP_OPEN_PAREN) {
-			parse_error(ps, FILT_ERR_UNBALANCED_PAREN, 0);
-			return -EINVAL;
-		}
-		postfix_append_op(ps, top_op);
+	if (quote) {
+		*err = last_quote;
+		return MISSING_QUOTE;
 	}
 
-	return 0;
-}
-
-static struct filter_pred *create_pred(struct filter_parse_state *ps,
-				       struct trace_event_call *call,
-				       enum filter_op_ids op,
-				       char *operand1, char *operand2)
-{
-	struct ftrace_event_field *field;
-	static struct filter_pred pred;
-
-	memset(&pred, 0, sizeof(pred));
-	pred.op = op;
-
-	if (op == OP_AND || op == OP_OR)
-		return &pred;
-
-	if (!operand1 || !operand2) {
-		parse_error(ps, FILT_ERR_MISSING_FIELD, 0);
-		return NULL;
-	}
-
-	field = trace_find_event_field(call, operand1);
-	if (!field) {
-		parse_error(ps, FILT_ERR_FIELD_NOT_FOUND, 0);
-		return NULL;
-	}
-
-	strcpy(pred.regex.pattern, operand2);
-	pred.regex.len = strlen(pred.regex.pattern);
-	pred.field = field;
-	return init_pred(ps, field, &pred) ? NULL : &pred;
-}
-
-static int check_preds(struct filter_parse_state *ps)
-{
-	int n_normal_preds = 0, n_logical_preds = 0;
-	struct postfix_elt *elt;
-	int cnt = 0;
-
-	list_for_each_entry(elt, &ps->postfix, list) {
-		if (elt->op == OP_NONE) {
-			cnt++;
-			continue;
-		}
+	if (open != 1) {
+		int level = open;
 
-		if (elt->op == OP_AND || elt->op == OP_OR) {
-			n_logical_preds++;
-			cnt--;
-			continue;
+		/* find the bad open */
+		for (i--; i; i--) {
+			if (quote) {
+				if (str[i] == quote)
+					quote = 0;
+				continue;
+			}
+			switch (str[i]) {
+			case '(':
+				if (level == open) {
+					*err = i;
+					return TOO_MANY_OPEN;
+				}
+				level--;
+				break;
+			case ')':
+				level++;
+				break;
+			case '\'':
+			case '"':
+				quote = str[i];
+				break;
+			}
 		}
-		if (elt->op != OP_NOT)
-			cnt--;
-		n_normal_preds++;
-		/* all ops should have operands */
-		if (cnt < 0)
-			break;
-	}
-
-	if (cnt != 1 || !n_normal_preds || n_logical_preds >= n_normal_preds) {
-		parse_error(ps, FILT_ERR_INVALID_FILTER, 0);
-		return -EINVAL;
+		/* First character is the '(' with missing ')' */
+		*err = 0;
+		return TOO_MANY_OPEN;
 	}
 
+	/* Set the size of the required stacks */
+	*parens = max_open;
+	*preds = nr_preds;
 	return 0;
 }
 
-static int count_preds(struct filter_parse_state *ps)
-{
-	struct postfix_elt *elt;
-	int n_preds = 0;
-
-	list_for_each_entry(elt, &ps->postfix, list) {
-		if (elt->op == OP_NONE)
-			continue;
-		n_preds++;
-	}
-
-	return n_preds;
-}
-
-struct check_pred_data {
-	int count;
-	int max;
-};
-
-static int check_pred_tree_cb(enum move_type move, struct filter_pred *pred,
-			      int *err, void *data)
-{
-	struct check_pred_data *d = data;
-
-	if (WARN_ON(d->count++ > d->max)) {
-		*err = -EINVAL;
-		return WALK_PRED_ABORT;
-	}
-	return WALK_PRED_DEFAULT;
-}
-
-/*
- * The tree is walked at filtering of an event. If the tree is not correctly
- * built, it may cause an infinite loop. Check here that the tree does
- * indeed terminate.
- */
-static int check_pred_tree(struct event_filter *filter,
-			   struct filter_pred *root)
-{
-	struct check_pred_data data = {
-		/*
-		 * The max that we can hit a node is three times.
-		 * Once going down, once coming up from left, and
-		 * once coming up from right. This is more than enough
-		 * since leafs are only hit a single time.
-		 */
-		.max   = 3 * filter->n_preds,
-		.count = 0,
-	};
-
-	return walk_pred_tree(filter->preds, root,
-			      check_pred_tree_cb, &data);
-}
-
-static int count_leafs_cb(enum move_type move, struct filter_pred *pred,
-			  int *err, void *data)
-{
-	int *count = data;
-
-	if ((move == MOVE_DOWN) &&
-	    (pred->left == FILTER_PRED_INVALID))
-		(*count)++;
-
-	return WALK_PRED_DEFAULT;
-}
-
-static int count_leafs(struct filter_pred *preds, struct filter_pred *root)
-{
-	int count = 0, ret;
-
-	ret = walk_pred_tree(preds, root, count_leafs_cb, &count);
-	WARN_ON(ret);
-	return count;
-}
-
-struct fold_pred_data {
-	struct filter_pred *root;
-	int count;
-	int children;
-};
-
-static int fold_pred_cb(enum move_type move, struct filter_pred *pred,
-			int *err, void *data)
-{
-	struct fold_pred_data *d = data;
-	struct filter_pred *root = d->root;
-
-	if (move != MOVE_DOWN)
-		return WALK_PRED_DEFAULT;
-	if (pred->left != FILTER_PRED_INVALID)
-		return WALK_PRED_DEFAULT;
-
-	if (WARN_ON(d->count == d->children)) {
-		*err = -EINVAL;
-		return WALK_PRED_ABORT;
-	}
-
-	pred->index &= ~FILTER_PRED_FOLD;
-	root->ops[d->count++] = pred->index;
-	return WALK_PRED_DEFAULT;
-}
-
-static int fold_pred(struct filter_pred *preds, struct filter_pred *root)
-{
-	struct fold_pred_data data = {
-		.root  = root,
-		.count = 0,
-	};
-	int children;
-
-	/* No need to keep the fold flag */
-	root->index &= ~FILTER_PRED_FOLD;
-
-	/* If the root is a leaf then do nothing */
-	if (root->left == FILTER_PRED_INVALID)
-		return 0;
-
-	/* count the children */
-	children = count_leafs(preds, &preds[root->left]);
-	children += count_leafs(preds, &preds[root->right]);
-
-	root->ops = kcalloc(children, sizeof(*root->ops), GFP_KERNEL);
-	if (!root->ops)
-		return -ENOMEM;
-
-	root->val = children;
-	data.children = children;
-	return walk_pred_tree(preds, root, fold_pred_cb, &data);
-}
-
-static int fold_pred_tree_cb(enum move_type move, struct filter_pred *pred,
-			     int *err, void *data)
-{
-	struct filter_pred *preds = data;
-
-	if (move != MOVE_DOWN)
-		return WALK_PRED_DEFAULT;
-	if (!(pred->index & FILTER_PRED_FOLD))
-		return WALK_PRED_DEFAULT;
-
-	*err = fold_pred(preds, pred);
-	if (*err)
-		return WALK_PRED_ABORT;
-
-	/* eveyrhing below is folded, continue with parent */
-	return WALK_PRED_PARENT;
-}
-
-/*
- * To optimize the processing of the ops, if we have several "ors" or
- * "ands" together, we can put them in an array and process them all
- * together speeding up the filter logic.
- */
-static int fold_pred_tree(struct event_filter *filter,
-			   struct filter_pred *root)
-{
-	return walk_pred_tree(filter->preds, root, fold_pred_tree_cb,
-			      filter->preds);
-}
-
-static int replace_preds(struct trace_event_call *call,
+static int process_preds(struct trace_event_call *call,
+			 const char *filter_string,
 			 struct event_filter *filter,
-			 struct filter_parse_state *ps,
-			 bool dry_run)
+			 struct filter_parse_error *pe)
 {
-	char *operand1 = NULL, *operand2 = NULL;
-	struct filter_pred *pred;
-	struct filter_pred *root;
-	struct postfix_elt *elt;
-	struct pred_stack stack = { }; /* init to NULL */
-	int err;
-	int n_preds = 0;
-
-	n_preds = count_preds(ps);
-	if (n_preds >= MAX_FILTER_PRED) {
-		parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0);
-		return -ENOSPC;
-	}
-
-	err = check_preds(ps);
-	if (err)
-		return err;
-
-	if (!dry_run) {
-		err = __alloc_pred_stack(&stack, n_preds);
-		if (err)
-			return err;
-		err = __alloc_preds(filter, n_preds);
-		if (err)
-			goto fail;
-	}
-
-	n_preds = 0;
-	list_for_each_entry(elt, &ps->postfix, list) {
-		if (elt->op == OP_NONE) {
-			if (!operand1)
-				operand1 = elt->operand;
-			else if (!operand2)
-				operand2 = elt->operand;
-			else {
-				parse_error(ps, FILT_ERR_TOO_MANY_OPERANDS, 0);
-				err = -EINVAL;
-				goto fail;
-			}
-			continue;
-		}
-
-		if (elt->op == OP_NOT) {
-			if (!n_preds || operand1 || operand2) {
-				parse_error(ps, FILT_ERR_ILLEGAL_NOT_OP, 0);
-				err = -EINVAL;
-				goto fail;
-			}
-			if (!dry_run)
-				filter->preds[n_preds - 1].not ^= 1;
-			continue;
-		}
-
-		if (WARN_ON(n_preds++ == MAX_FILTER_PRED)) {
-			parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0);
-			err = -ENOSPC;
-			goto fail;
-		}
-
-		pred = create_pred(ps, call, elt->op, operand1, operand2);
-		if (!pred) {
-			err = -EINVAL;
-			goto fail;
-		}
+	struct prog_entry *prog;
+	int nr_parens;
+	int nr_preds;
+	int index;
+	int ret;
 
-		if (!dry_run) {
-			err = filter_add_pred(ps, filter, pred, &stack);
-			if (err)
-				goto fail;
+	ret = calc_stack(filter_string, &nr_parens, &nr_preds, &index);
+	if (ret < 0) {
+		switch (ret) {
+		case MISSING_QUOTE:
+			parse_error(pe, FILT_ERR_MISSING_QUOTE, index);
+			break;
+		case TOO_MANY_OPEN:
+			parse_error(pe, FILT_ERR_TOO_MANY_OPEN, index);
+			break;
+		default:
+			parse_error(pe, FILT_ERR_TOO_MANY_CLOSE, index);
 		}
-
-		operand1 = operand2 = NULL;
+		return ret;
 	}
 
-	if (!dry_run) {
-		/* We should have one item left on the stack */
-		pred = __pop_pred_stack(&stack);
-		if (!pred)
-			return -EINVAL;
-		/* This item is where we start from in matching */
-		root = pred;
-		/* Make sure the stack is empty */
-		pred = __pop_pred_stack(&stack);
-		if (WARN_ON(pred)) {
-			err = -EINVAL;
-			filter->root = NULL;
-			goto fail;
-		}
-		err = check_pred_tree(filter, root);
-		if (err)
-			goto fail;
-
-		/* Optimize the tree */
-		err = fold_pred_tree(filter, root);
-		if (err)
-			goto fail;
-
-		/* We don't set root until we know it works */
-		barrier();
-		filter->root = root;
+	if (!nr_preds) {
+		prog = NULL;
+	} else {
+		prog = predicate_parse(filter_string, nr_parens, nr_preds,
+			       parse_pred, call, pe);
+		if (IS_ERR(prog))
+			return PTR_ERR(prog);
 	}
-
-	err = 0;
-fail:
-	__free_pred_stack(&stack);
-	return err;
+	rcu_assign_pointer(filter->prog, prog);
+	return 0;
 }
 
 static inline void event_set_filtered_flag(struct trace_event_file *file)
@@ -1780,72 +1558,53 @@ struct filter_list {
 	struct event_filter	*filter;
 };
 
-static int replace_system_preds(struct trace_subsystem_dir *dir,
+static int process_system_preds(struct trace_subsystem_dir *dir,
 				struct trace_array *tr,
-				struct filter_parse_state *ps,
+				struct filter_parse_error *pe,
 				char *filter_string)
 {
 	struct trace_event_file *file;
 	struct filter_list *filter_item;
+	struct event_filter *filter = NULL;
 	struct filter_list *tmp;
 	LIST_HEAD(filter_list);
 	bool fail = true;
 	int err;
 
 	list_for_each_entry(file, &tr->events, list) {
-		if (file->system != dir)
-			continue;
-
-		/*
-		 * Try to see if the filter can be applied
-		 *  (filter arg is ignored on dry_run)
-		 */
-		err = replace_preds(file->event_call, NULL, ps, true);
-		if (err)
-			event_set_no_set_filter_flag(file);
-		else
-			event_clear_no_set_filter_flag(file);
-	}
-
-	list_for_each_entry(file, &tr->events, list) {
-		struct event_filter *filter;
 
 		if (file->system != dir)
 			continue;
 
-		if (event_no_set_filter_flag(file))
-			continue;
-
-		filter_item = kzalloc(sizeof(*filter_item), GFP_KERNEL);
-		if (!filter_item)
-			goto fail_mem;
-
-		list_add_tail(&filter_item->list, &filter_list);
-
-		filter_item->filter = __alloc_filter();
-		if (!filter_item->filter)
+		filter = kzalloc(sizeof(*filter), GFP_KERNEL);
+		if (!filter)
 			goto fail_mem;
-		filter = filter_item->filter;
 
-		/* Can only fail on no memory */
-		err = replace_filter_string(filter, filter_string);
-		if (err)
+		filter->filter_string = kstrdup(filter_string, GFP_KERNEL);
+		if (!filter->filter_string)
 			goto fail_mem;
 
-		err = replace_preds(file->event_call, filter, ps, false);
+		err = process_preds(file->event_call, filter_string, filter, pe);
 		if (err) {
 			filter_disable(file);
-			parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);
-			append_filter_err(ps, filter);
+			parse_error(pe, FILT_ERR_BAD_SUBSYS_FILTER, 0);
+			append_filter_err(pe, filter);
 		} else
 			event_set_filtered_flag(file);
+
+
+		filter_item = kzalloc(sizeof(*filter_item), GFP_KERNEL);
+		if (!filter_item)
+			goto fail_mem;
+
+		list_add_tail(&filter_item->list, &filter_list);
 		/*
 		 * Regardless of if this returned an error, we still
 		 * replace the filter for the call.
 		 */
-		filter = event_filter(file);
-		event_set_filter(file, filter_item->filter);
-		filter_item->filter = filter;
+		filter_item->filter = event_filter(file);
+		event_set_filter(file, filter);
+		filter = NULL;
 
 		fail = false;
 	}
@@ -1871,9 +1630,10 @@ static int replace_system_preds(struct trace_subsystem_dir *dir,
 		list_del(&filter_item->list);
 		kfree(filter_item);
 	}
-	parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);
+	parse_error(pe, FILT_ERR_BAD_SUBSYS_FILTER, 0);
 	return -EINVAL;
  fail_mem:
+	kfree(filter);
 	/* If any call succeeded, we still need to sync */
 	if (!fail)
 		synchronize_sched();
@@ -1885,47 +1645,42 @@ static int replace_system_preds(struct trace_subsystem_dir *dir,
 	return -ENOMEM;
 }
 
-static int create_filter_start(char *filter_str, bool set_str,
-			       struct filter_parse_state **psp,
+static int create_filter_start(char *filter_string, bool set_str,
+			       struct filter_parse_error **pse,
 			       struct event_filter **filterp)
 {
 	struct event_filter *filter;
-	struct filter_parse_state *ps = NULL;
+	struct filter_parse_error *pe = NULL;
 	int err = 0;
 
-	WARN_ON_ONCE(*psp || *filterp);
+	if (WARN_ON_ONCE(*pse || *filterp))
+		return -EINVAL;
 
-	/* allocate everything, and if any fails, free all and fail */
-	filter = __alloc_filter();
-	if (filter && set_str)
-		err = replace_filter_string(filter, filter_str);
+	filter = kzalloc(sizeof(*filter), GFP_KERNEL);
+	if (filter && set_str) {
+		filter->filter_string = kstrdup(filter_string, GFP_KERNEL);
+		if (!filter->filter_string)
+			err = -ENOMEM;
+	}
 
-	ps = kzalloc(sizeof(*ps), GFP_KERNEL);
+	pe = kzalloc(sizeof(*pe), GFP_KERNEL);
 
-	if (!filter || !ps || err) {
-		kfree(ps);
+	if (!filter || !pe || err) {
+		kfree(pe);
 		__free_filter(filter);
 		return -ENOMEM;
 	}
 
 	/* we're committed to creating a new filter */
 	*filterp = filter;
-	*psp = ps;
+	*pse = pe;
 
-	parse_init(ps, filter_ops, filter_str);
-	err = filter_parse(ps);
-	if (err && set_str)
-		append_filter_err(ps, filter);
-	return err;
+	return 0;
 }
 
-static void create_filter_finish(struct filter_parse_state *ps)
+static void create_filter_finish(struct filter_parse_error *pe)
 {
-	if (ps) {
-		filter_opstack_clear(ps);
-		postfix_clear(ps);
-		kfree(ps);
-	}
+	kfree(pe);
 }
 
 /**
@@ -1945,24 +1700,20 @@ static void create_filter_finish(struct filter_parse_state *ps)
  * freeing it.
  */
 static int create_filter(struct trace_event_call *call,
-			 char *filter_str, bool set_str,
+			 char *filter_string, bool set_str,
 			 struct event_filter **filterp)
 {
+	struct filter_parse_error *pe = NULL;
 	struct event_filter *filter = NULL;
-	struct filter_parse_state *ps = NULL;
 	int err;
 
-	err = create_filter_start(filter_str, set_str, &ps, &filter);
-	if (!err) {
-		err = replace_preds(call, filter, ps, false);
-		if (err && set_str)
-			append_filter_err(ps, filter);
-	}
-	if (err && !set_str) {
-		free_event_filter(filter);
-		filter = NULL;
-	}
-	create_filter_finish(ps);
+	err = create_filter_start(filter_string, set_str, &pe, &filter);
+	if (err)
+		return err;
+
+	err = process_preds(call, filter_string, filter, pe);
+	if (err && set_str)
+		append_filter_err(pe, filter);
 
 	*filterp = filter;
 	return err;
@@ -1989,21 +1740,21 @@ static int create_system_filter(struct trace_subsystem_dir *dir,
 				char *filter_str, struct event_filter **filterp)
 {
 	struct event_filter *filter = NULL;
-	struct filter_parse_state *ps = NULL;
+	struct filter_parse_error *pe = NULL;
 	int err;
 
-	err = create_filter_start(filter_str, true, &ps, &filter);
+	err = create_filter_start(filter_str, true, &pe, &filter);
 	if (!err) {
-		err = replace_system_preds(dir, tr, ps, filter_str);
+		err = process_system_preds(dir, tr, pe, filter_str);
 		if (!err) {
 			/* System filters just show a default message */
 			kfree(filter->filter_string);
 			filter->filter_string = NULL;
 		} else {
-			append_filter_err(ps, filter);
+			append_filter_err(pe, filter);
 		}
 	}
-	create_filter_finish(ps);
+	create_filter_finish(pe);
 
 	*filterp = filter;
 	return err;
@@ -2186,66 +1937,80 @@ static int __ftrace_function_set_filter(int filter, char *buf, int len,
 	return ret;
 }
 
-static int ftrace_function_check_pred(struct filter_pred *pred, int leaf)
+static int ftrace_function_check_pred(struct filter_pred *pred)
 {
 	struct ftrace_event_field *field = pred->field;
 
-	if (leaf) {
-		/*
-		 * Check the leaf predicate for function trace, verify:
-		 *  - only '==' and '!=' is used
-		 *  - the 'ip' field is used
-		 */
-		if ((pred->op != OP_EQ) && (pred->op != OP_NE))
-			return -EINVAL;
+	/*
+	 * Check the predicate for function trace, verify:
+	 *  - only '==' and '!=' is used
+	 *  - the 'ip' field is used
+	 */
+	if ((pred->op != OP_EQ) && (pred->op != OP_NE))
+		return -EINVAL;
 
-		if (strcmp(field->name, "ip"))
-			return -EINVAL;
-	} else {
-		/*
-		 * Check the non leaf predicate for function trace, verify:
-		 *  - only '||' is used
-		*/
-		if (pred->op != OP_OR)
-			return -EINVAL;
-	}
+	if (strcmp(field->name, "ip"))
+		return -EINVAL;
 
 	return 0;
 }
 
-static int ftrace_function_set_filter_cb(enum move_type move,
-					 struct filter_pred *pred,
-					 int *err, void *data)
+static int ftrace_function_set_filter_pred(struct filter_pred *pred,
+					   struct function_filter_data *data)
 {
+	int ret;
+
 	/* Checking the node is valid for function trace. */
-	if ((move != MOVE_DOWN) ||
-	    (pred->left != FILTER_PRED_INVALID)) {
-		*err = ftrace_function_check_pred(pred, 0);
-	} else {
-		*err = ftrace_function_check_pred(pred, 1);
-		if (*err)
-			return WALK_PRED_ABORT;
-
-		*err = __ftrace_function_set_filter(pred->op == OP_EQ,
-						    pred->regex.pattern,
-						    pred->regex.len,
-						    data);
-	}
+	ret = ftrace_function_check_pred(pred);
+	if (ret)
+		return ret;
 
-	return (*err) ? WALK_PRED_ABORT : WALK_PRED_DEFAULT;
+	return __ftrace_function_set_filter(pred->op == OP_EQ,
+					    pred->regex.pattern,
+					    pred->regex.len,
+					    data);
+}
+
+static bool is_or(struct prog_entry *prog, int i)
+{
+	int target;
+
+	/*
+	 * Only "||" is allowed for function events, thus,
+	 * all true branches should jump to true, and any
+	 * false branch should jump to false.
+	 */
+	target = prog[i].target + 1;
+	/* True and false have NULL preds (all prog entries should jump to one */
+	if (prog[target].pred)
+		return false;
+
+	/* prog[target].target is 1 for TRUE, 0 for FALSE */
+	return prog[i].when_to_branch == prog[target].target;
 }
 
 static int ftrace_function_set_filter(struct perf_event *event,
 				      struct event_filter *filter)
 {
+	struct prog_entry *prog = rcu_dereference_protected(filter->prog,
+						lockdep_is_held(&event_mutex));
 	struct function_filter_data data = {
 		.first_filter  = 1,
 		.first_notrace = 1,
 		.ops           = &event->ftrace_ops,
 	};
+	int i;
 
-	return walk_pred_tree(filter->preds, filter->root,
-			      ftrace_function_set_filter_cb, &data);
+	for (i = 0; prog[i].pred; i++) {
+		struct filter_pred *pred = prog[i].pred;
+
+		if (!is_or(prog, i))
+			return -EINVAL;
+
+		if (ftrace_function_set_filter_pred(pred, &data) < 0)
+			return -EINVAL;
+	}
+	return 0;
 }
 #else
 static int ftrace_function_set_filter(struct perf_event *event,
@@ -2388,26 +2153,28 @@ static int test_pred_visited_fn(struct filter_pred *pred, void *event)
 	return 1;
 }
 
-static int test_walk_pred_cb(enum move_type move, struct filter_pred *pred,
-			     int *err, void *data)
+static void update_pred_fn(struct event_filter *filter, char *fields)
 {
-	char *fields = data;
+	struct prog_entry *prog = rcu_dereference_protected(filter->prog,
+						lockdep_is_held(&event_mutex));
+	int i;
 
-	if ((move == MOVE_DOWN) &&
-	    (pred->left == FILTER_PRED_INVALID)) {
+	for (i = 0; prog[i].pred; i++) {
+		struct filter_pred *pred = prog[i].pred;
 		struct ftrace_event_field *field = pred->field;
 
+		WARN_ON_ONCE(!pred->fn);
+
 		if (!field) {
-			WARN(1, "all leafs should have field defined");
-			return WALK_PRED_DEFAULT;
+			WARN_ONCE(1, "all leafs should have field defined %d", i);
+			continue;
 		}
+
 		if (!strchr(fields, *field->name))
-			return WALK_PRED_DEFAULT;
+			continue;
 
-		WARN_ON(!pred->fn);
 		pred->fn = test_pred_visited_fn;
 	}
-	return WALK_PRED_DEFAULT;
 }
 
 static __init int ftrace_test_event_filter(void)
@@ -2431,20 +2198,22 @@ static __init int ftrace_test_event_filter(void)
 			break;
 		}
 
+		/* Needed to dereference filter->prog */
+		mutex_lock(&event_mutex);
 		/*
 		 * The preemption disabling is not really needed for self
 		 * tests, but the rcu dereference will complain without it.
 		 */
 		preempt_disable();
 		if (*d->not_visited)
-			walk_pred_tree(filter->preds, filter->root,
-				       test_walk_pred_cb,
-				       d->not_visited);
+			update_pred_fn(filter, d->not_visited);
 
 		test_pred_visited = 0;
 		err = filter_match_preds(filter, &d->rec);
 		preempt_enable();
 
+		mutex_unlock(&event_mutex);
+
 		__free_filter(filter);
 
 		if (test_pred_visited) {
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1e1558c99d56..0d7b3ffbecc2 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -20,15 +20,39 @@
 #include <linux/slab.h>
 #include <linux/stacktrace.h>
 #include <linux/rculist.h>
+#include <linux/tracefs.h>
 
 #include "tracing_map.h"
 #include "trace.h"
 
+#define SYNTH_SYSTEM		"synthetic"
+#define SYNTH_FIELDS_MAX	16
+
+#define STR_VAR_LEN_MAX		32 /* must be multiple of sizeof(u64) */
+
 struct hist_field;
 
-typedef u64 (*hist_field_fn_t) (struct hist_field *field, void *event);
+typedef u64 (*hist_field_fn_t) (struct hist_field *field,
+				struct tracing_map_elt *elt,
+				struct ring_buffer_event *rbe,
+				void *event);
 
 #define HIST_FIELD_OPERANDS_MAX	2
+#define HIST_FIELDS_MAX		(TRACING_MAP_FIELDS_MAX + TRACING_MAP_VARS_MAX)
+#define HIST_ACTIONS_MAX	8
+
+enum field_op_id {
+	FIELD_OP_NONE,
+	FIELD_OP_PLUS,
+	FIELD_OP_MINUS,
+	FIELD_OP_UNARY_MINUS,
+};
+
+struct hist_var {
+	char				*name;
+	struct hist_trigger_data	*hist_data;
+	unsigned int			idx;
+};
 
 struct hist_field {
 	struct ftrace_event_field	*field;
@@ -37,27 +61,49 @@ struct hist_field {
 	unsigned int			size;
 	unsigned int			offset;
 	unsigned int                    is_signed;
+	const char			*type;
 	struct hist_field		*operands[HIST_FIELD_OPERANDS_MAX];
+	struct hist_trigger_data	*hist_data;
+	struct hist_var			var;
+	enum field_op_id		operator;
+	char				*system;
+	char				*event_name;
+	char				*name;
+	unsigned int			var_idx;
+	unsigned int			var_ref_idx;
+	bool                            read_once;
 };
 
-static u64 hist_field_none(struct hist_field *field, void *event)
+static u64 hist_field_none(struct hist_field *field,
+			   struct tracing_map_elt *elt,
+			   struct ring_buffer_event *rbe,
+			   void *event)
 {
 	return 0;
 }
 
-static u64 hist_field_counter(struct hist_field *field, void *event)
+static u64 hist_field_counter(struct hist_field *field,
+			      struct tracing_map_elt *elt,
+			      struct ring_buffer_event *rbe,
+			      void *event)
 {
 	return 1;
 }
 
-static u64 hist_field_string(struct hist_field *hist_field, void *event)
+static u64 hist_field_string(struct hist_field *hist_field,
+			     struct tracing_map_elt *elt,
+			     struct ring_buffer_event *rbe,
+			     void *event)
 {
 	char *addr = (char *)(event + hist_field->field->offset);
 
 	return (u64)(unsigned long)addr;
 }
 
-static u64 hist_field_dynstring(struct hist_field *hist_field, void *event)
+static u64 hist_field_dynstring(struct hist_field *hist_field,
+				struct tracing_map_elt *elt,
+				struct ring_buffer_event *rbe,
+				void *event)
 {
 	u32 str_item = *(u32 *)(event + hist_field->field->offset);
 	int str_loc = str_item & 0xffff;
@@ -66,24 +112,74 @@ static u64 hist_field_dynstring(struct hist_field *hist_field, void *event)
 	return (u64)(unsigned long)addr;
 }
 
-static u64 hist_field_pstring(struct hist_field *hist_field, void *event)
+static u64 hist_field_pstring(struct hist_field *hist_field,
+			      struct tracing_map_elt *elt,
+			      struct ring_buffer_event *rbe,
+			      void *event)
 {
 	char **addr = (char **)(event + hist_field->field->offset);
 
 	return (u64)(unsigned long)*addr;
 }
 
-static u64 hist_field_log2(struct hist_field *hist_field, void *event)
+static u64 hist_field_log2(struct hist_field *hist_field,
+			   struct tracing_map_elt *elt,
+			   struct ring_buffer_event *rbe,
+			   void *event)
 {
 	struct hist_field *operand = hist_field->operands[0];
 
-	u64 val = operand->fn(operand, event);
+	u64 val = operand->fn(operand, elt, rbe, event);
 
 	return (u64) ilog2(roundup_pow_of_two(val));
 }
 
+static u64 hist_field_plus(struct hist_field *hist_field,
+			   struct tracing_map_elt *elt,
+			   struct ring_buffer_event *rbe,
+			   void *event)
+{
+	struct hist_field *operand1 = hist_field->operands[0];
+	struct hist_field *operand2 = hist_field->operands[1];
+
+	u64 val1 = operand1->fn(operand1, elt, rbe, event);
+	u64 val2 = operand2->fn(operand2, elt, rbe, event);
+
+	return val1 + val2;
+}
+
+static u64 hist_field_minus(struct hist_field *hist_field,
+			    struct tracing_map_elt *elt,
+			    struct ring_buffer_event *rbe,
+			    void *event)
+{
+	struct hist_field *operand1 = hist_field->operands[0];
+	struct hist_field *operand2 = hist_field->operands[1];
+
+	u64 val1 = operand1->fn(operand1, elt, rbe, event);
+	u64 val2 = operand2->fn(operand2, elt, rbe, event);
+
+	return val1 - val2;
+}
+
+static u64 hist_field_unary_minus(struct hist_field *hist_field,
+				  struct tracing_map_elt *elt,
+				  struct ring_buffer_event *rbe,
+				  void *event)
+{
+	struct hist_field *operand = hist_field->operands[0];
+
+	s64 sval = (s64)operand->fn(operand, elt, rbe, event);
+	u64 val = (u64)-sval;
+
+	return val;
+}
+
 #define DEFINE_HIST_FIELD_FN(type)					\
-static u64 hist_field_##type(struct hist_field *hist_field, void *event)\
+	static u64 hist_field_##type(struct hist_field *hist_field,	\
+				     struct tracing_map_elt *elt,	\
+				     struct ring_buffer_event *rbe,	\
+				     void *event)			\
 {									\
 	type *addr = (type *)(event + hist_field->field->offset);	\
 									\
@@ -126,6 +222,19 @@ enum hist_field_flags {
 	HIST_FIELD_FL_SYSCALL		= 1 << 7,
 	HIST_FIELD_FL_STACKTRACE	= 1 << 8,
 	HIST_FIELD_FL_LOG2		= 1 << 9,
+	HIST_FIELD_FL_TIMESTAMP		= 1 << 10,
+	HIST_FIELD_FL_TIMESTAMP_USECS	= 1 << 11,
+	HIST_FIELD_FL_VAR		= 1 << 12,
+	HIST_FIELD_FL_EXPR		= 1 << 13,
+	HIST_FIELD_FL_VAR_REF		= 1 << 14,
+	HIST_FIELD_FL_CPU		= 1 << 15,
+	HIST_FIELD_FL_ALIAS		= 1 << 16,
+};
+
+struct var_defs {
+	unsigned int	n_vars;
+	char		*name[TRACING_MAP_VARS_MAX];
+	char		*expr[TRACING_MAP_VARS_MAX];
 };
 
 struct hist_trigger_attrs {
@@ -133,25 +242,1437 @@ struct hist_trigger_attrs {
 	char		*vals_str;
 	char		*sort_key_str;
 	char		*name;
+	char		*clock;
 	bool		pause;
 	bool		cont;
 	bool		clear;
+	bool		ts_in_usecs;
 	unsigned int	map_bits;
+
+	char		*assignment_str[TRACING_MAP_VARS_MAX];
+	unsigned int	n_assignments;
+
+	char		*action_str[HIST_ACTIONS_MAX];
+	unsigned int	n_actions;
+
+	struct var_defs	var_defs;
+};
+
+struct field_var {
+	struct hist_field	*var;
+	struct hist_field	*val;
+};
+
+struct field_var_hist {
+	struct hist_trigger_data	*hist_data;
+	char				*cmd;
 };
 
 struct hist_trigger_data {
-	struct hist_field               *fields[TRACING_MAP_FIELDS_MAX];
+	struct hist_field               *fields[HIST_FIELDS_MAX];
 	unsigned int			n_vals;
 	unsigned int			n_keys;
 	unsigned int			n_fields;
+	unsigned int			n_vars;
 	unsigned int			key_size;
 	struct tracing_map_sort_key	sort_keys[TRACING_MAP_SORT_KEYS_MAX];
 	unsigned int			n_sort_keys;
 	struct trace_event_file		*event_file;
 	struct hist_trigger_attrs	*attrs;
 	struct tracing_map		*map;
+	bool				enable_timestamps;
+	bool				remove;
+	struct hist_field               *var_refs[TRACING_MAP_VARS_MAX];
+	unsigned int			n_var_refs;
+
+	struct action_data		*actions[HIST_ACTIONS_MAX];
+	unsigned int			n_actions;
+
+	struct hist_field               *synth_var_refs[SYNTH_FIELDS_MAX];
+	unsigned int                    n_synth_var_refs;
+	struct field_var		*field_vars[SYNTH_FIELDS_MAX];
+	unsigned int			n_field_vars;
+	unsigned int			n_field_var_str;
+	struct field_var_hist		*field_var_hists[SYNTH_FIELDS_MAX];
+	unsigned int			n_field_var_hists;
+
+	struct field_var		*max_vars[SYNTH_FIELDS_MAX];
+	unsigned int			n_max_vars;
+	unsigned int			n_max_var_str;
+};
+
+struct synth_field {
+	char *type;
+	char *name;
+	size_t size;
+	bool is_signed;
+	bool is_string;
+};
+
+struct synth_event {
+	struct list_head			list;
+	int					ref;
+	char					*name;
+	struct synth_field			**fields;
+	unsigned int				n_fields;
+	unsigned int				n_u64;
+	struct trace_event_class		class;
+	struct trace_event_call			call;
+	struct tracepoint			*tp;
+};
+
+struct action_data;
+
+typedef void (*action_fn_t) (struct hist_trigger_data *hist_data,
+			     struct tracing_map_elt *elt, void *rec,
+			     struct ring_buffer_event *rbe,
+			     struct action_data *data, u64 *var_ref_vals);
+
+struct action_data {
+	action_fn_t		fn;
+	unsigned int		n_params;
+	char			*params[SYNTH_FIELDS_MAX];
+
+	union {
+		struct {
+			unsigned int		var_ref_idx;
+			char			*match_event;
+			char			*match_event_system;
+			char			*synth_event_name;
+			struct synth_event	*synth_event;
+		} onmatch;
+
+		struct {
+			char			*var_str;
+			char			*fn_name;
+			unsigned int		max_var_ref_idx;
+			struct hist_field	*max_var;
+			struct hist_field	*var;
+		} onmax;
+	};
+};
+
+
+static char last_hist_cmd[MAX_FILTER_STR_VAL];
+static char hist_err_str[MAX_FILTER_STR_VAL];
+
+static void last_cmd_set(char *str)
+{
+	if (!str)
+		return;
+
+	strncpy(last_hist_cmd, str, MAX_FILTER_STR_VAL - 1);
+}
+
+static void hist_err(char *str, char *var)
+{
+	int maxlen = MAX_FILTER_STR_VAL - 1;
+
+	if (!str)
+		return;
+
+	if (strlen(hist_err_str))
+		return;
+
+	if (!var)
+		var = "";
+
+	if (strlen(hist_err_str) + strlen(str) + strlen(var) > maxlen)
+		return;
+
+	strcat(hist_err_str, str);
+	strcat(hist_err_str, var);
+}
+
+static void hist_err_event(char *str, char *system, char *event, char *var)
+{
+	char err[MAX_FILTER_STR_VAL];
+
+	if (system && var)
+		snprintf(err, MAX_FILTER_STR_VAL, "%s.%s.%s", system, event, var);
+	else if (system)
+		snprintf(err, MAX_FILTER_STR_VAL, "%s.%s", system, event);
+	else
+		strncpy(err, var, MAX_FILTER_STR_VAL);
+
+	hist_err(str, err);
+}
+
+static void hist_err_clear(void)
+{
+	hist_err_str[0] = '\0';
+}
+
+static bool have_hist_err(void)
+{
+	if (strlen(hist_err_str))
+		return true;
+
+	return false;
+}
+
+static LIST_HEAD(synth_event_list);
+static DEFINE_MUTEX(synth_event_mutex);
+
+struct synth_trace_event {
+	struct trace_entry	ent;
+	u64			fields[];
+};
+
+static int synth_event_define_fields(struct trace_event_call *call)
+{
+	struct synth_trace_event trace;
+	int offset = offsetof(typeof(trace), fields);
+	struct synth_event *event = call->data;
+	unsigned int i, size, n_u64;
+	char *name, *type;
+	bool is_signed;
+	int ret = 0;
+
+	for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
+		size = event->fields[i]->size;
+		is_signed = event->fields[i]->is_signed;
+		type = event->fields[i]->type;
+		name = event->fields[i]->name;
+		ret = trace_define_field(call, type, name, offset, size,
+					 is_signed, FILTER_OTHER);
+		if (ret)
+			break;
+
+		if (event->fields[i]->is_string) {
+			offset += STR_VAR_LEN_MAX;
+			n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
+		} else {
+			offset += sizeof(u64);
+			n_u64++;
+		}
+	}
+
+	event->n_u64 = n_u64;
+
+	return ret;
+}
+
+static bool synth_field_signed(char *type)
+{
+	if (strncmp(type, "u", 1) == 0)
+		return false;
+
+	return true;
+}
+
+static int synth_field_is_string(char *type)
+{
+	if (strstr(type, "char[") != NULL)
+		return true;
+
+	return false;
+}
+
+static int synth_field_string_size(char *type)
+{
+	char buf[4], *end, *start;
+	unsigned int len;
+	int size, err;
+
+	start = strstr(type, "char[");
+	if (start == NULL)
+		return -EINVAL;
+	start += strlen("char[");
+
+	end = strchr(type, ']');
+	if (!end || end < start)
+		return -EINVAL;
+
+	len = end - start;
+	if (len > 3)
+		return -EINVAL;
+
+	strncpy(buf, start, len);
+	buf[len] = '\0';
+
+	err = kstrtouint(buf, 0, &size);
+	if (err)
+		return err;
+
+	if (size > STR_VAR_LEN_MAX)
+		return -EINVAL;
+
+	return size;
+}
+
+static int synth_field_size(char *type)
+{
+	int size = 0;
+
+	if (strcmp(type, "s64") == 0)
+		size = sizeof(s64);
+	else if (strcmp(type, "u64") == 0)
+		size = sizeof(u64);
+	else if (strcmp(type, "s32") == 0)
+		size = sizeof(s32);
+	else if (strcmp(type, "u32") == 0)
+		size = sizeof(u32);
+	else if (strcmp(type, "s16") == 0)
+		size = sizeof(s16);
+	else if (strcmp(type, "u16") == 0)
+		size = sizeof(u16);
+	else if (strcmp(type, "s8") == 0)
+		size = sizeof(s8);
+	else if (strcmp(type, "u8") == 0)
+		size = sizeof(u8);
+	else if (strcmp(type, "char") == 0)
+		size = sizeof(char);
+	else if (strcmp(type, "unsigned char") == 0)
+		size = sizeof(unsigned char);
+	else if (strcmp(type, "int") == 0)
+		size = sizeof(int);
+	else if (strcmp(type, "unsigned int") == 0)
+		size = sizeof(unsigned int);
+	else if (strcmp(type, "long") == 0)
+		size = sizeof(long);
+	else if (strcmp(type, "unsigned long") == 0)
+		size = sizeof(unsigned long);
+	else if (strcmp(type, "pid_t") == 0)
+		size = sizeof(pid_t);
+	else if (synth_field_is_string(type))
+		size = synth_field_string_size(type);
+
+	return size;
+}
+
+static const char *synth_field_fmt(char *type)
+{
+	const char *fmt = "%llu";
+
+	if (strcmp(type, "s64") == 0)
+		fmt = "%lld";
+	else if (strcmp(type, "u64") == 0)
+		fmt = "%llu";
+	else if (strcmp(type, "s32") == 0)
+		fmt = "%d";
+	else if (strcmp(type, "u32") == 0)
+		fmt = "%u";
+	else if (strcmp(type, "s16") == 0)
+		fmt = "%d";
+	else if (strcmp(type, "u16") == 0)
+		fmt = "%u";
+	else if (strcmp(type, "s8") == 0)
+		fmt = "%d";
+	else if (strcmp(type, "u8") == 0)
+		fmt = "%u";
+	else if (strcmp(type, "char") == 0)
+		fmt = "%d";
+	else if (strcmp(type, "unsigned char") == 0)
+		fmt = "%u";
+	else if (strcmp(type, "int") == 0)
+		fmt = "%d";
+	else if (strcmp(type, "unsigned int") == 0)
+		fmt = "%u";
+	else if (strcmp(type, "long") == 0)
+		fmt = "%ld";
+	else if (strcmp(type, "unsigned long") == 0)
+		fmt = "%lu";
+	else if (strcmp(type, "pid_t") == 0)
+		fmt = "%d";
+	else if (synth_field_is_string(type))
+		fmt = "%s";
+
+	return fmt;
+}
+
+static enum print_line_t print_synth_event(struct trace_iterator *iter,
+					   int flags,
+					   struct trace_event *event)
+{
+	struct trace_array *tr = iter->tr;
+	struct trace_seq *s = &iter->seq;
+	struct synth_trace_event *entry;
+	struct synth_event *se;
+	unsigned int i, n_u64;
+	char print_fmt[32];
+	const char *fmt;
+
+	entry = (struct synth_trace_event *)iter->ent;
+	se = container_of(event, struct synth_event, call.event);
+
+	trace_seq_printf(s, "%s: ", se->name);
+
+	for (i = 0, n_u64 = 0; i < se->n_fields; i++) {
+		if (trace_seq_has_overflowed(s))
+			goto end;
+
+		fmt = synth_field_fmt(se->fields[i]->type);
+
+		/* parameter types */
+		if (tr->trace_flags & TRACE_ITER_VERBOSE)
+			trace_seq_printf(s, "%s ", fmt);
+
+		snprintf(print_fmt, sizeof(print_fmt), "%%s=%s%%s", fmt);
+
+		/* parameter values */
+		if (se->fields[i]->is_string) {
+			trace_seq_printf(s, print_fmt, se->fields[i]->name,
+					 (char *)&entry->fields[n_u64],
+					 i == se->n_fields - 1 ? "" : " ");
+			n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
+		} else {
+			trace_seq_printf(s, print_fmt, se->fields[i]->name,
+					 entry->fields[n_u64],
+					 i == se->n_fields - 1 ? "" : " ");
+			n_u64++;
+		}
+	}
+end:
+	trace_seq_putc(s, '\n');
+
+	return trace_handle_return(s);
+}
+
+static struct trace_event_functions synth_event_funcs = {
+	.trace		= print_synth_event
+};
+
+static notrace void trace_event_raw_event_synth(void *__data,
+						u64 *var_ref_vals,
+						unsigned int var_ref_idx)
+{
+	struct trace_event_file *trace_file = __data;
+	struct synth_trace_event *entry;
+	struct trace_event_buffer fbuffer;
+	struct ring_buffer *buffer;
+	struct synth_event *event;
+	unsigned int i, n_u64;
+	int fields_size = 0;
+
+	event = trace_file->event_call->data;
+
+	if (trace_trigger_soft_disabled(trace_file))
+		return;
+
+	fields_size = event->n_u64 * sizeof(u64);
+
+	/*
+	 * Avoid ring buffer recursion detection, as this event
+	 * is being performed within another event.
+	 */
+	buffer = trace_file->tr->trace_buffer.buffer;
+	ring_buffer_nest_start(buffer);
+
+	entry = trace_event_buffer_reserve(&fbuffer, trace_file,
+					   sizeof(*entry) + fields_size);
+	if (!entry)
+		goto out;
+
+	for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
+		if (event->fields[i]->is_string) {
+			char *str_val = (char *)(long)var_ref_vals[var_ref_idx + i];
+			char *str_field = (char *)&entry->fields[n_u64];
+
+			strscpy(str_field, str_val, STR_VAR_LEN_MAX);
+			n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
+		} else {
+			entry->fields[n_u64] = var_ref_vals[var_ref_idx + i];
+			n_u64++;
+		}
+	}
+
+	trace_event_buffer_commit(&fbuffer);
+out:
+	ring_buffer_nest_end(buffer);
+}
+
+static void free_synth_event_print_fmt(struct trace_event_call *call)
+{
+	if (call) {
+		kfree(call->print_fmt);
+		call->print_fmt = NULL;
+	}
+}
+
+static int __set_synth_event_print_fmt(struct synth_event *event,
+				       char *buf, int len)
+{
+	const char *fmt;
+	int pos = 0;
+	int i;
+
+	/* When len=0, we just calculate the needed length */
+#define LEN_OR_ZERO (len ? len - pos : 0)
+
+	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
+	for (i = 0; i < event->n_fields; i++) {
+		fmt = synth_field_fmt(event->fields[i]->type);
+		pos += snprintf(buf + pos, LEN_OR_ZERO, "%s=%s%s",
+				event->fields[i]->name, fmt,
+				i == event->n_fields - 1 ? "" : ", ");
+	}
+	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
+
+	for (i = 0; i < event->n_fields; i++) {
+		pos += snprintf(buf + pos, LEN_OR_ZERO,
+				", REC->%s", event->fields[i]->name);
+	}
+
+#undef LEN_OR_ZERO
+
+	/* return the length of print_fmt */
+	return pos;
+}
+
+static int set_synth_event_print_fmt(struct trace_event_call *call)
+{
+	struct synth_event *event = call->data;
+	char *print_fmt;
+	int len;
+
+	/* First: called with 0 length to calculate the needed length */
+	len = __set_synth_event_print_fmt(event, NULL, 0);
+
+	print_fmt = kmalloc(len + 1, GFP_KERNEL);
+	if (!print_fmt)
+		return -ENOMEM;
+
+	/* Second: actually write the @print_fmt */
+	__set_synth_event_print_fmt(event, print_fmt, len + 1);
+	call->print_fmt = print_fmt;
+
+	return 0;
+}
+
+static void free_synth_field(struct synth_field *field)
+{
+	kfree(field->type);
+	kfree(field->name);
+	kfree(field);
+}
+
+static struct synth_field *parse_synth_field(char *field_type,
+					     char *field_name)
+{
+	struct synth_field *field;
+	int len, ret = 0;
+	char *array;
+
+	if (field_type[0] == ';')
+		field_type++;
+
+	len = strlen(field_name);
+	if (field_name[len - 1] == ';')
+		field_name[len - 1] = '\0';
+
+	field = kzalloc(sizeof(*field), GFP_KERNEL);
+	if (!field)
+		return ERR_PTR(-ENOMEM);
+
+	len = strlen(field_type) + 1;
+	array = strchr(field_name, '[');
+	if (array)
+		len += strlen(array);
+	field->type = kzalloc(len, GFP_KERNEL);
+	if (!field->type) {
+		ret = -ENOMEM;
+		goto free;
+	}
+	strcat(field->type, field_type);
+	if (array) {
+		strcat(field->type, array);
+		*array = '\0';
+	}
+
+	field->size = synth_field_size(field->type);
+	if (!field->size) {
+		ret = -EINVAL;
+		goto free;
+	}
+
+	if (synth_field_is_string(field->type))
+		field->is_string = true;
+
+	field->is_signed = synth_field_signed(field->type);
+
+	field->name = kstrdup(field_name, GFP_KERNEL);
+	if (!field->name) {
+		ret = -ENOMEM;
+		goto free;
+	}
+ out:
+	return field;
+ free:
+	free_synth_field(field);
+	field = ERR_PTR(ret);
+	goto out;
+}
+
+static void free_synth_tracepoint(struct tracepoint *tp)
+{
+	if (!tp)
+		return;
+
+	kfree(tp->name);
+	kfree(tp);
+}
+
+static struct tracepoint *alloc_synth_tracepoint(char *name)
+{
+	struct tracepoint *tp;
+
+	tp = kzalloc(sizeof(*tp), GFP_KERNEL);
+	if (!tp)
+		return ERR_PTR(-ENOMEM);
+
+	tp->name = kstrdup(name, GFP_KERNEL);
+	if (!tp->name) {
+		kfree(tp);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	return tp;
+}
+
+typedef void (*synth_probe_func_t) (void *__data, u64 *var_ref_vals,
+				    unsigned int var_ref_idx);
+
+static inline void trace_synth(struct synth_event *event, u64 *var_ref_vals,
+			       unsigned int var_ref_idx)
+{
+	struct tracepoint *tp = event->tp;
+
+	if (unlikely(atomic_read(&tp->key.enabled) > 0)) {
+		struct tracepoint_func *probe_func_ptr;
+		synth_probe_func_t probe_func;
+		void *__data;
+
+		if (!(cpu_online(raw_smp_processor_id())))
+			return;
+
+		probe_func_ptr = rcu_dereference_sched((tp)->funcs);
+		if (probe_func_ptr) {
+			do {
+				probe_func = probe_func_ptr->func;
+				__data = probe_func_ptr->data;
+				probe_func(__data, var_ref_vals, var_ref_idx);
+			} while ((++probe_func_ptr)->func);
+		}
+	}
+}
+
+static struct synth_event *find_synth_event(const char *name)
+{
+	struct synth_event *event;
+
+	list_for_each_entry(event, &synth_event_list, list) {
+		if (strcmp(event->name, name) == 0)
+			return event;
+	}
+
+	return NULL;
+}
+
+static int register_synth_event(struct synth_event *event)
+{
+	struct trace_event_call *call = &event->call;
+	int ret = 0;
+
+	event->call.class = &event->class;
+	event->class.system = kstrdup(SYNTH_SYSTEM, GFP_KERNEL);
+	if (!event->class.system) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	event->tp = alloc_synth_tracepoint(event->name);
+	if (IS_ERR(event->tp)) {
+		ret = PTR_ERR(event->tp);
+		event->tp = NULL;
+		goto out;
+	}
+
+	INIT_LIST_HEAD(&call->class->fields);
+	call->event.funcs = &synth_event_funcs;
+	call->class->define_fields = synth_event_define_fields;
+
+	ret = register_trace_event(&call->event);
+	if (!ret) {
+		ret = -ENODEV;
+		goto out;
+	}
+	call->flags = TRACE_EVENT_FL_TRACEPOINT;
+	call->class->reg = trace_event_reg;
+	call->class->probe = trace_event_raw_event_synth;
+	call->data = event;
+	call->tp = event->tp;
+
+	ret = trace_add_event_call(call);
+	if (ret) {
+		pr_warn("Failed to register synthetic event: %s\n",
+			trace_event_name(call));
+		goto err;
+	}
+
+	ret = set_synth_event_print_fmt(call);
+	if (ret < 0) {
+		trace_remove_event_call(call);
+		goto err;
+	}
+ out:
+	return ret;
+ err:
+	unregister_trace_event(&call->event);
+	goto out;
+}
+
+static int unregister_synth_event(struct synth_event *event)
+{
+	struct trace_event_call *call = &event->call;
+	int ret;
+
+	ret = trace_remove_event_call(call);
+
+	return ret;
+}
+
+static void free_synth_event(struct synth_event *event)
+{
+	unsigned int i;
+
+	if (!event)
+		return;
+
+	for (i = 0; i < event->n_fields; i++)
+		free_synth_field(event->fields[i]);
+
+	kfree(event->fields);
+	kfree(event->name);
+	kfree(event->class.system);
+	free_synth_tracepoint(event->tp);
+	free_synth_event_print_fmt(&event->call);
+	kfree(event);
+}
+
+static struct synth_event *alloc_synth_event(char *event_name, int n_fields,
+					     struct synth_field **fields)
+{
+	struct synth_event *event;
+	unsigned int i;
+
+	event = kzalloc(sizeof(*event), GFP_KERNEL);
+	if (!event) {
+		event = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	event->name = kstrdup(event_name, GFP_KERNEL);
+	if (!event->name) {
+		kfree(event);
+		event = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	event->fields = kcalloc(n_fields, sizeof(*event->fields), GFP_KERNEL);
+	if (!event->fields) {
+		free_synth_event(event);
+		event = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	for (i = 0; i < n_fields; i++)
+		event->fields[i] = fields[i];
+
+	event->n_fields = n_fields;
+ out:
+	return event;
+}
+
+static void action_trace(struct hist_trigger_data *hist_data,
+			 struct tracing_map_elt *elt, void *rec,
+			 struct ring_buffer_event *rbe,
+			 struct action_data *data, u64 *var_ref_vals)
+{
+	struct synth_event *event = data->onmatch.synth_event;
+
+	trace_synth(event, var_ref_vals, data->onmatch.var_ref_idx);
+}
+
+struct hist_var_data {
+	struct list_head list;
+	struct hist_trigger_data *hist_data;
+};
+
+static void add_or_delete_synth_event(struct synth_event *event, int delete)
+{
+	if (delete)
+		free_synth_event(event);
+	else {
+		mutex_lock(&synth_event_mutex);
+		if (!find_synth_event(event->name))
+			list_add(&event->list, &synth_event_list);
+		else
+			free_synth_event(event);
+		mutex_unlock(&synth_event_mutex);
+	}
+}
+
+static int create_synth_event(int argc, char **argv)
+{
+	struct synth_field *field, *fields[SYNTH_FIELDS_MAX];
+	struct synth_event *event = NULL;
+	bool delete_event = false;
+	int i, n_fields = 0, ret = 0;
+	char *name;
+
+	mutex_lock(&synth_event_mutex);
+
+	/*
+	 * Argument syntax:
+	 *  - Add synthetic event: <event_name> field[;field] ...
+	 *  - Remove synthetic event: !<event_name> field[;field] ...
+	 *      where 'field' = type field_name
+	 */
+	if (argc < 1) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	name = argv[0];
+	if (name[0] == '!') {
+		delete_event = true;
+		name++;
+	}
+
+	event = find_synth_event(name);
+	if (event) {
+		if (delete_event) {
+			if (event->ref) {
+				event = NULL;
+				ret = -EBUSY;
+				goto out;
+			}
+			list_del(&event->list);
+			goto out;
+		}
+		event = NULL;
+		ret = -EEXIST;
+		goto out;
+	} else if (delete_event)
+		goto out;
+
+	if (argc < 2) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	for (i = 1; i < argc - 1; i++) {
+		if (strcmp(argv[i], ";") == 0)
+			continue;
+		if (n_fields == SYNTH_FIELDS_MAX) {
+			ret = -EINVAL;
+			goto err;
+		}
+
+		field = parse_synth_field(argv[i], argv[i + 1]);
+		if (IS_ERR(field)) {
+			ret = PTR_ERR(field);
+			goto err;
+		}
+		fields[n_fields] = field;
+		i++; n_fields++;
+	}
+
+	if (i < argc) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	event = alloc_synth_event(name, n_fields, fields);
+	if (IS_ERR(event)) {
+		ret = PTR_ERR(event);
+		event = NULL;
+		goto err;
+	}
+ out:
+	mutex_unlock(&synth_event_mutex);
+
+	if (event) {
+		if (delete_event) {
+			ret = unregister_synth_event(event);
+			add_or_delete_synth_event(event, !ret);
+		} else {
+			ret = register_synth_event(event);
+			add_or_delete_synth_event(event, ret);
+		}
+	}
+
+	return ret;
+ err:
+	mutex_unlock(&synth_event_mutex);
+
+	for (i = 0; i < n_fields; i++)
+		free_synth_field(fields[i]);
+	free_synth_event(event);
+
+	return ret;
+}
+
+static int release_all_synth_events(void)
+{
+	struct list_head release_events;
+	struct synth_event *event, *e;
+	int ret = 0;
+
+	INIT_LIST_HEAD(&release_events);
+
+	mutex_lock(&synth_event_mutex);
+
+	list_for_each_entry(event, &synth_event_list, list) {
+		if (event->ref) {
+			mutex_unlock(&synth_event_mutex);
+			return -EBUSY;
+		}
+	}
+
+	list_splice_init(&event->list, &release_events);
+
+	mutex_unlock(&synth_event_mutex);
+
+	list_for_each_entry_safe(event, e, &release_events, list) {
+		list_del(&event->list);
+
+		ret = unregister_synth_event(event);
+		add_or_delete_synth_event(event, !ret);
+	}
+
+	return ret;
+}
+
+
+static void *synth_events_seq_start(struct seq_file *m, loff_t *pos)
+{
+	mutex_lock(&synth_event_mutex);
+
+	return seq_list_start(&synth_event_list, *pos);
+}
+
+static void *synth_events_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return seq_list_next(v, &synth_event_list, pos);
+}
+
+static void synth_events_seq_stop(struct seq_file *m, void *v)
+{
+	mutex_unlock(&synth_event_mutex);
+}
+
+static int synth_events_seq_show(struct seq_file *m, void *v)
+{
+	struct synth_field *field;
+	struct synth_event *event = v;
+	unsigned int i;
+
+	seq_printf(m, "%s\t", event->name);
+
+	for (i = 0; i < event->n_fields; i++) {
+		field = event->fields[i];
+
+		/* parameter values */
+		seq_printf(m, "%s %s%s", field->type, field->name,
+			   i == event->n_fields - 1 ? "" : "; ");
+	}
+
+	seq_putc(m, '\n');
+
+	return 0;
+}
+
+static const struct seq_operations synth_events_seq_op = {
+	.start  = synth_events_seq_start,
+	.next   = synth_events_seq_next,
+	.stop   = synth_events_seq_stop,
+	.show   = synth_events_seq_show
+};
+
+static int synth_events_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
+		ret = release_all_synth_events();
+		if (ret < 0)
+			return ret;
+	}
+
+	return seq_open(file, &synth_events_seq_op);
+}
+
+static ssize_t synth_events_write(struct file *file,
+				  const char __user *buffer,
+				  size_t count, loff_t *ppos)
+{
+	return trace_parse_run_command(file, buffer, count, ppos,
+				       create_synth_event);
+}
+
+static const struct file_operations synth_events_fops = {
+	.open           = synth_events_open,
+	.write		= synth_events_write,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = seq_release,
+};
+
+static u64 hist_field_timestamp(struct hist_field *hist_field,
+				struct tracing_map_elt *elt,
+				struct ring_buffer_event *rbe,
+				void *event)
+{
+	struct hist_trigger_data *hist_data = hist_field->hist_data;
+	struct trace_array *tr = hist_data->event_file->tr;
+
+	u64 ts = ring_buffer_event_time_stamp(rbe);
+
+	if (hist_data->attrs->ts_in_usecs && trace_clock_in_ns(tr))
+		ts = ns2usecs(ts);
+
+	return ts;
+}
+
+static u64 hist_field_cpu(struct hist_field *hist_field,
+			  struct tracing_map_elt *elt,
+			  struct ring_buffer_event *rbe,
+			  void *event)
+{
+	int cpu = smp_processor_id();
+
+	return cpu;
+}
+
+static struct hist_field *
+check_field_for_var_ref(struct hist_field *hist_field,
+			struct hist_trigger_data *var_data,
+			unsigned int var_idx)
+{
+	struct hist_field *found = NULL;
+
+	if (hist_field && hist_field->flags & HIST_FIELD_FL_VAR_REF) {
+		if (hist_field->var.idx == var_idx &&
+		    hist_field->var.hist_data == var_data) {
+			found = hist_field;
+		}
+	}
+
+	return found;
+}
+
+static struct hist_field *
+check_field_for_var_refs(struct hist_trigger_data *hist_data,
+			 struct hist_field *hist_field,
+			 struct hist_trigger_data *var_data,
+			 unsigned int var_idx,
+			 unsigned int level)
+{
+	struct hist_field *found = NULL;
+	unsigned int i;
+
+	if (level > 3)
+		return found;
+
+	if (!hist_field)
+		return found;
+
+	found = check_field_for_var_ref(hist_field, var_data, var_idx);
+	if (found)
+		return found;
+
+	for (i = 0; i < HIST_FIELD_OPERANDS_MAX; i++) {
+		struct hist_field *operand;
+
+		operand = hist_field->operands[i];
+		found = check_field_for_var_refs(hist_data, operand, var_data,
+						 var_idx, level + 1);
+		if (found)
+			return found;
+	}
+
+	return found;
+}
+
+static struct hist_field *find_var_ref(struct hist_trigger_data *hist_data,
+				       struct hist_trigger_data *var_data,
+				       unsigned int var_idx)
+{
+	struct hist_field *hist_field, *found = NULL;
+	unsigned int i;
+
+	for_each_hist_field(i, hist_data) {
+		hist_field = hist_data->fields[i];
+		found = check_field_for_var_refs(hist_data, hist_field,
+						 var_data, var_idx, 0);
+		if (found)
+			return found;
+	}
+
+	for (i = 0; i < hist_data->n_synth_var_refs; i++) {
+		hist_field = hist_data->synth_var_refs[i];
+		found = check_field_for_var_refs(hist_data, hist_field,
+						 var_data, var_idx, 0);
+		if (found)
+			return found;
+	}
+
+	return found;
+}
+
+static struct hist_field *find_any_var_ref(struct hist_trigger_data *hist_data,
+					   unsigned int var_idx)
+{
+	struct trace_array *tr = hist_data->event_file->tr;
+	struct hist_field *found = NULL;
+	struct hist_var_data *var_data;
+
+	list_for_each_entry(var_data, &tr->hist_vars, list) {
+		if (var_data->hist_data == hist_data)
+			continue;
+		found = find_var_ref(var_data->hist_data, hist_data, var_idx);
+		if (found)
+			break;
+	}
+
+	return found;
+}
+
+static bool check_var_refs(struct hist_trigger_data *hist_data)
+{
+	struct hist_field *field;
+	bool found = false;
+	int i;
+
+	for_each_hist_field(i, hist_data) {
+		field = hist_data->fields[i];
+		if (field && field->flags & HIST_FIELD_FL_VAR) {
+			if (find_any_var_ref(hist_data, field->var.idx)) {
+				found = true;
+				break;
+			}
+		}
+	}
+
+	return found;
+}
+
+static struct hist_var_data *find_hist_vars(struct hist_trigger_data *hist_data)
+{
+	struct trace_array *tr = hist_data->event_file->tr;
+	struct hist_var_data *var_data, *found = NULL;
+
+	list_for_each_entry(var_data, &tr->hist_vars, list) {
+		if (var_data->hist_data == hist_data) {
+			found = var_data;
+			break;
+		}
+	}
+
+	return found;
+}
+
+static bool field_has_hist_vars(struct hist_field *hist_field,
+				unsigned int level)
+{
+	int i;
+
+	if (level > 3)
+		return false;
+
+	if (!hist_field)
+		return false;
+
+	if (hist_field->flags & HIST_FIELD_FL_VAR ||
+	    hist_field->flags & HIST_FIELD_FL_VAR_REF)
+		return true;
+
+	for (i = 0; i < HIST_FIELD_OPERANDS_MAX; i++) {
+		struct hist_field *operand;
+
+		operand = hist_field->operands[i];
+		if (field_has_hist_vars(operand, level + 1))
+			return true;
+	}
+
+	return false;
+}
+
+static bool has_hist_vars(struct hist_trigger_data *hist_data)
+{
+	struct hist_field *hist_field;
+	int i;
+
+	for_each_hist_field(i, hist_data) {
+		hist_field = hist_data->fields[i];
+		if (field_has_hist_vars(hist_field, 0))
+			return true;
+	}
+
+	return false;
+}
+
+static int save_hist_vars(struct hist_trigger_data *hist_data)
+{
+	struct trace_array *tr = hist_data->event_file->tr;
+	struct hist_var_data *var_data;
+
+	var_data = find_hist_vars(hist_data);
+	if (var_data)
+		return 0;
+
+	if (trace_array_get(tr) < 0)
+		return -ENODEV;
+
+	var_data = kzalloc(sizeof(*var_data), GFP_KERNEL);
+	if (!var_data) {
+		trace_array_put(tr);
+		return -ENOMEM;
+	}
+
+	var_data->hist_data = hist_data;
+	list_add(&var_data->list, &tr->hist_vars);
+
+	return 0;
+}
+
+static void remove_hist_vars(struct hist_trigger_data *hist_data)
+{
+	struct trace_array *tr = hist_data->event_file->tr;
+	struct hist_var_data *var_data;
+
+	var_data = find_hist_vars(hist_data);
+	if (!var_data)
+		return;
+
+	if (WARN_ON(check_var_refs(hist_data)))
+		return;
+
+	list_del(&var_data->list);
+
+	kfree(var_data);
+
+	trace_array_put(tr);
+}
+
+static struct hist_field *find_var_field(struct hist_trigger_data *hist_data,
+					 const char *var_name)
+{
+	struct hist_field *hist_field, *found = NULL;
+	int i;
+
+	for_each_hist_field(i, hist_data) {
+		hist_field = hist_data->fields[i];
+		if (hist_field && hist_field->flags & HIST_FIELD_FL_VAR &&
+		    strcmp(hist_field->var.name, var_name) == 0) {
+			found = hist_field;
+			break;
+		}
+	}
+
+	return found;
+}
+
+static struct hist_field *find_var(struct hist_trigger_data *hist_data,
+				   struct trace_event_file *file,
+				   const char *var_name)
+{
+	struct hist_trigger_data *test_data;
+	struct event_trigger_data *test;
+	struct hist_field *hist_field;
+
+	hist_field = find_var_field(hist_data, var_name);
+	if (hist_field)
+		return hist_field;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			test_data = test->private_data;
+			hist_field = find_var_field(test_data, var_name);
+			if (hist_field)
+				return hist_field;
+		}
+	}
+
+	return NULL;
+}
+
+static struct trace_event_file *find_var_file(struct trace_array *tr,
+					      char *system,
+					      char *event_name,
+					      char *var_name)
+{
+	struct hist_trigger_data *var_hist_data;
+	struct hist_var_data *var_data;
+	struct trace_event_file *file, *found = NULL;
+
+	if (system)
+		return find_event_file(tr, system, event_name);
+
+	list_for_each_entry(var_data, &tr->hist_vars, list) {
+		var_hist_data = var_data->hist_data;
+		file = var_hist_data->event_file;
+		if (file == found)
+			continue;
+
+		if (find_var_field(var_hist_data, var_name)) {
+			if (found) {
+				hist_err_event("Variable name not unique, need to use fully qualified name (subsys.event.var) for variable: ", system, event_name, var_name);
+				return NULL;
+			}
+
+			found = file;
+		}
+	}
+
+	return found;
+}
+
+static struct hist_field *find_file_var(struct trace_event_file *file,
+					const char *var_name)
+{
+	struct hist_trigger_data *test_data;
+	struct event_trigger_data *test;
+	struct hist_field *hist_field;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			test_data = test->private_data;
+			hist_field = find_var_field(test_data, var_name);
+			if (hist_field)
+				return hist_field;
+		}
+	}
+
+	return NULL;
+}
+
+static struct hist_field *
+find_match_var(struct hist_trigger_data *hist_data, char *var_name)
+{
+	struct trace_array *tr = hist_data->event_file->tr;
+	struct hist_field *hist_field, *found = NULL;
+	struct trace_event_file *file;
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		struct action_data *data = hist_data->actions[i];
+
+		if (data->fn == action_trace) {
+			char *system = data->onmatch.match_event_system;
+			char *event_name = data->onmatch.match_event;
+
+			file = find_var_file(tr, system, event_name, var_name);
+			if (!file)
+				continue;
+			hist_field = find_file_var(file, var_name);
+			if (hist_field) {
+				if (found) {
+					hist_err_event("Variable name not unique, need to use fully qualified name (subsys.event.var) for variable: ", system, event_name, var_name);
+					return ERR_PTR(-EINVAL);
+				}
+
+				found = hist_field;
+			}
+		}
+	}
+	return found;
+}
+
+static struct hist_field *find_event_var(struct hist_trigger_data *hist_data,
+					 char *system,
+					 char *event_name,
+					 char *var_name)
+{
+	struct trace_array *tr = hist_data->event_file->tr;
+	struct hist_field *hist_field = NULL;
+	struct trace_event_file *file;
+
+	if (!system || !event_name) {
+		hist_field = find_match_var(hist_data, var_name);
+		if (IS_ERR(hist_field))
+			return NULL;
+		if (hist_field)
+			return hist_field;
+	}
+
+	file = find_var_file(tr, system, event_name, var_name);
+	if (!file)
+		return NULL;
+
+	hist_field = find_file_var(file, var_name);
+
+	return hist_field;
+}
+
+struct hist_elt_data {
+	char *comm;
+	u64 *var_ref_vals;
+	char *field_var_str[SYNTH_FIELDS_MAX];
 };
 
+static u64 hist_field_var_ref(struct hist_field *hist_field,
+			      struct tracing_map_elt *elt,
+			      struct ring_buffer_event *rbe,
+			      void *event)
+{
+	struct hist_elt_data *elt_data;
+	u64 var_val = 0;
+
+	elt_data = elt->private_data;
+	var_val = elt_data->var_ref_vals[hist_field->var_ref_idx];
+
+	return var_val;
+}
+
+static bool resolve_var_refs(struct hist_trigger_data *hist_data, void *key,
+			     u64 *var_ref_vals, bool self)
+{
+	struct hist_trigger_data *var_data;
+	struct tracing_map_elt *var_elt;
+	struct hist_field *hist_field;
+	unsigned int i, var_idx;
+	bool resolved = true;
+	u64 var_val = 0;
+
+	for (i = 0; i < hist_data->n_var_refs; i++) {
+		hist_field = hist_data->var_refs[i];
+		var_idx = hist_field->var.idx;
+		var_data = hist_field->var.hist_data;
+
+		if (var_data == NULL) {
+			resolved = false;
+			break;
+		}
+
+		if ((self && var_data != hist_data) ||
+		    (!self && var_data == hist_data))
+			continue;
+
+		var_elt = tracing_map_lookup(var_data->map, key);
+		if (!var_elt) {
+			resolved = false;
+			break;
+		}
+
+		if (!tracing_map_var_set(var_elt, var_idx)) {
+			resolved = false;
+			break;
+		}
+
+		if (self || !hist_field->read_once)
+			var_val = tracing_map_read_var(var_elt, var_idx);
+		else
+			var_val = tracing_map_read_var_once(var_elt, var_idx);
+
+		var_ref_vals[i] = var_val;
+	}
+
+	return resolved;
+}
+
 static const char *hist_field_name(struct hist_field *field,
 				   unsigned int level)
 {
@@ -162,8 +1683,26 @@ static const char *hist_field_name(struct hist_field *field,
 
 	if (field->field)
 		field_name = field->field->name;
-	else if (field->flags & HIST_FIELD_FL_LOG2)
+	else if (field->flags & HIST_FIELD_FL_LOG2 ||
+		 field->flags & HIST_FIELD_FL_ALIAS)
 		field_name = hist_field_name(field->operands[0], ++level);
+	else if (field->flags & HIST_FIELD_FL_CPU)
+		field_name = "cpu";
+	else if (field->flags & HIST_FIELD_FL_EXPR ||
+		 field->flags & HIST_FIELD_FL_VAR_REF) {
+		if (field->system) {
+			static char full_name[MAX_FILTER_STR_VAL];
+
+			strcat(full_name, field->system);
+			strcat(full_name, ".");
+			strcat(full_name, field->event_name);
+			strcat(full_name, ".");
+			strcat(full_name, field->name);
+			field_name = full_name;
+		} else
+			field_name = field->name;
+	} else if (field->flags & HIST_FIELD_FL_TIMESTAMP)
+		field_name = "common_timestamp";
 
 	if (field_name == NULL)
 		field_name = "";
@@ -232,16 +1771,119 @@ static int parse_map_size(char *str)
 
 static void destroy_hist_trigger_attrs(struct hist_trigger_attrs *attrs)
 {
+	unsigned int i;
+
 	if (!attrs)
 		return;
 
+	for (i = 0; i < attrs->n_assignments; i++)
+		kfree(attrs->assignment_str[i]);
+
+	for (i = 0; i < attrs->n_actions; i++)
+		kfree(attrs->action_str[i]);
+
 	kfree(attrs->name);
 	kfree(attrs->sort_key_str);
 	kfree(attrs->keys_str);
 	kfree(attrs->vals_str);
+	kfree(attrs->clock);
 	kfree(attrs);
 }
 
+static int parse_action(char *str, struct hist_trigger_attrs *attrs)
+{
+	int ret = -EINVAL;
+
+	if (attrs->n_actions >= HIST_ACTIONS_MAX)
+		return ret;
+
+	if ((strncmp(str, "onmatch(", strlen("onmatch(")) == 0) ||
+	    (strncmp(str, "onmax(", strlen("onmax(")) == 0)) {
+		attrs->action_str[attrs->n_actions] = kstrdup(str, GFP_KERNEL);
+		if (!attrs->action_str[attrs->n_actions]) {
+			ret = -ENOMEM;
+			return ret;
+		}
+		attrs->n_actions++;
+		ret = 0;
+	}
+
+	return ret;
+}
+
+static int parse_assignment(char *str, struct hist_trigger_attrs *attrs)
+{
+	int ret = 0;
+
+	if ((strncmp(str, "key=", strlen("key=")) == 0) ||
+	    (strncmp(str, "keys=", strlen("keys=")) == 0)) {
+		attrs->keys_str = kstrdup(str, GFP_KERNEL);
+		if (!attrs->keys_str) {
+			ret = -ENOMEM;
+			goto out;
+		}
+	} else if ((strncmp(str, "val=", strlen("val=")) == 0) ||
+		 (strncmp(str, "vals=", strlen("vals=")) == 0) ||
+		 (strncmp(str, "values=", strlen("values=")) == 0)) {
+		attrs->vals_str = kstrdup(str, GFP_KERNEL);
+		if (!attrs->vals_str) {
+			ret = -ENOMEM;
+			goto out;
+		}
+	} else if (strncmp(str, "sort=", strlen("sort=")) == 0) {
+		attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
+		if (!attrs->sort_key_str) {
+			ret = -ENOMEM;
+			goto out;
+		}
+	} else if (strncmp(str, "name=", strlen("name=")) == 0) {
+		attrs->name = kstrdup(str, GFP_KERNEL);
+		if (!attrs->name) {
+			ret = -ENOMEM;
+			goto out;
+		}
+	} else if (strncmp(str, "clock=", strlen("clock=")) == 0) {
+		strsep(&str, "=");
+		if (!str) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		str = strstrip(str);
+		attrs->clock = kstrdup(str, GFP_KERNEL);
+		if (!attrs->clock) {
+			ret = -ENOMEM;
+			goto out;
+		}
+	} else if (strncmp(str, "size=", strlen("size=")) == 0) {
+		int map_bits = parse_map_size(str);
+
+		if (map_bits < 0) {
+			ret = map_bits;
+			goto out;
+		}
+		attrs->map_bits = map_bits;
+	} else {
+		char *assignment;
+
+		if (attrs->n_assignments == TRACING_MAP_VARS_MAX) {
+			hist_err("Too many variables defined: ", str);
+			ret = -EINVAL;
+			goto out;
+		}
+
+		assignment = kstrdup(str, GFP_KERNEL);
+		if (!assignment) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		attrs->assignment_str[attrs->n_assignments++] = assignment;
+	}
+ out:
+	return ret;
+}
+
 static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str)
 {
 	struct hist_trigger_attrs *attrs;
@@ -254,35 +1896,21 @@ static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str)
 	while (trigger_str) {
 		char *str = strsep(&trigger_str, ":");
 
-		if ((strncmp(str, "key=", strlen("key=")) == 0) ||
-		    (strncmp(str, "keys=", strlen("keys=")) == 0))
-			attrs->keys_str = kstrdup(str, GFP_KERNEL);
-		else if ((strncmp(str, "val=", strlen("val=")) == 0) ||
-			 (strncmp(str, "vals=", strlen("vals=")) == 0) ||
-			 (strncmp(str, "values=", strlen("values=")) == 0))
-			attrs->vals_str = kstrdup(str, GFP_KERNEL);
-		else if (strncmp(str, "sort=", strlen("sort=")) == 0)
-			attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
-		else if (strncmp(str, "name=", strlen("name=")) == 0)
-			attrs->name = kstrdup(str, GFP_KERNEL);
-		else if (strcmp(str, "pause") == 0)
+		if (strchr(str, '=')) {
+			ret = parse_assignment(str, attrs);
+			if (ret)
+				goto free;
+		} else if (strcmp(str, "pause") == 0)
 			attrs->pause = true;
 		else if ((strcmp(str, "cont") == 0) ||
 			 (strcmp(str, "continue") == 0))
 			attrs->cont = true;
 		else if (strcmp(str, "clear") == 0)
 			attrs->clear = true;
-		else if (strncmp(str, "size=", strlen("size=")) == 0) {
-			int map_bits = parse_map_size(str);
-
-			if (map_bits < 0) {
-				ret = map_bits;
+		else {
+			ret = parse_action(str, attrs);
+			if (ret)
 				goto free;
-			}
-			attrs->map_bits = map_bits;
-		} else {
-			ret = -EINVAL;
-			goto free;
 		}
 	}
 
@@ -291,6 +1919,14 @@ static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str)
 		goto free;
 	}
 
+	if (!attrs->clock) {
+		attrs->clock = kstrdup("global", GFP_KERNEL);
+		if (!attrs->clock) {
+			ret = -ENOMEM;
+			goto free;
+		}
+	}
+
 	return attrs;
  free:
 	destroy_hist_trigger_attrs(attrs);
@@ -313,64 +1949,203 @@ static inline void save_comm(char *comm, struct task_struct *task)
 	memcpy(comm, task->comm, TASK_COMM_LEN);
 }
 
-static void hist_trigger_elt_comm_free(struct tracing_map_elt *elt)
+static void hist_elt_data_free(struct hist_elt_data *elt_data)
 {
-	kfree((char *)elt->private_data);
+	unsigned int i;
+
+	for (i = 0; i < SYNTH_FIELDS_MAX; i++)
+		kfree(elt_data->field_var_str[i]);
+
+	kfree(elt_data->comm);
+	kfree(elt_data);
 }
 
-static int hist_trigger_elt_comm_alloc(struct tracing_map_elt *elt)
+static void hist_trigger_elt_data_free(struct tracing_map_elt *elt)
+{
+	struct hist_elt_data *elt_data = elt->private_data;
+
+	hist_elt_data_free(elt_data);
+}
+
+static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt)
 {
 	struct hist_trigger_data *hist_data = elt->map->private_data;
+	unsigned int size = TASK_COMM_LEN;
+	struct hist_elt_data *elt_data;
 	struct hist_field *key_field;
-	unsigned int i;
+	unsigned int i, n_str;
+
+	elt_data = kzalloc(sizeof(*elt_data), GFP_KERNEL);
+	if (!elt_data)
+		return -ENOMEM;
 
 	for_each_hist_key_field(i, hist_data) {
 		key_field = hist_data->fields[i];
 
 		if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
-			unsigned int size = TASK_COMM_LEN + 1;
-
-			elt->private_data = kzalloc(size, GFP_KERNEL);
-			if (!elt->private_data)
+			elt_data->comm = kzalloc(size, GFP_KERNEL);
+			if (!elt_data->comm) {
+				kfree(elt_data);
 				return -ENOMEM;
+			}
 			break;
 		}
 	}
 
+	n_str = hist_data->n_field_var_str + hist_data->n_max_var_str;
+
+	size = STR_VAR_LEN_MAX;
+
+	for (i = 0; i < n_str; i++) {
+		elt_data->field_var_str[i] = kzalloc(size, GFP_KERNEL);
+		if (!elt_data->field_var_str[i]) {
+			hist_elt_data_free(elt_data);
+			return -ENOMEM;
+		}
+	}
+
+	elt->private_data = elt_data;
+
 	return 0;
 }
 
-static void hist_trigger_elt_comm_copy(struct tracing_map_elt *to,
-				       struct tracing_map_elt *from)
+static void hist_trigger_elt_data_init(struct tracing_map_elt *elt)
+{
+	struct hist_elt_data *elt_data = elt->private_data;
+
+	if (elt_data->comm)
+		save_comm(elt_data->comm, current);
+}
+
+static const struct tracing_map_ops hist_trigger_elt_data_ops = {
+	.elt_alloc	= hist_trigger_elt_data_alloc,
+	.elt_free	= hist_trigger_elt_data_free,
+	.elt_init	= hist_trigger_elt_data_init,
+};
+
+static const char *get_hist_field_flags(struct hist_field *hist_field)
+{
+	const char *flags_str = NULL;
+
+	if (hist_field->flags & HIST_FIELD_FL_HEX)
+		flags_str = "hex";
+	else if (hist_field->flags & HIST_FIELD_FL_SYM)
+		flags_str = "sym";
+	else if (hist_field->flags & HIST_FIELD_FL_SYM_OFFSET)
+		flags_str = "sym-offset";
+	else if (hist_field->flags & HIST_FIELD_FL_EXECNAME)
+		flags_str = "execname";
+	else if (hist_field->flags & HIST_FIELD_FL_SYSCALL)
+		flags_str = "syscall";
+	else if (hist_field->flags & HIST_FIELD_FL_LOG2)
+		flags_str = "log2";
+	else if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP_USECS)
+		flags_str = "usecs";
+
+	return flags_str;
+}
+
+static void expr_field_str(struct hist_field *field, char *expr)
 {
-	char *comm_from = from->private_data;
-	char *comm_to = to->private_data;
+	if (field->flags & HIST_FIELD_FL_VAR_REF)
+		strcat(expr, "$");
+
+	strcat(expr, hist_field_name(field, 0));
 
-	if (comm_from)
-		memcpy(comm_to, comm_from, TASK_COMM_LEN + 1);
+	if (field->flags && !(field->flags & HIST_FIELD_FL_VAR_REF)) {
+		const char *flags_str = get_hist_field_flags(field);
+
+		if (flags_str) {
+			strcat(expr, ".");
+			strcat(expr, flags_str);
+		}
+	}
 }
 
-static void hist_trigger_elt_comm_init(struct tracing_map_elt *elt)
+static char *expr_str(struct hist_field *field, unsigned int level)
 {
-	char *comm = elt->private_data;
+	char *expr;
+
+	if (level > 1)
+		return NULL;
+
+	expr = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL);
+	if (!expr)
+		return NULL;
+
+	if (!field->operands[0]) {
+		expr_field_str(field, expr);
+		return expr;
+	}
+
+	if (field->operator == FIELD_OP_UNARY_MINUS) {
+		char *subexpr;
 
-	if (comm)
-		save_comm(comm, current);
+		strcat(expr, "-(");
+		subexpr = expr_str(field->operands[0], ++level);
+		if (!subexpr) {
+			kfree(expr);
+			return NULL;
+		}
+		strcat(expr, subexpr);
+		strcat(expr, ")");
+
+		kfree(subexpr);
+
+		return expr;
+	}
+
+	expr_field_str(field->operands[0], expr);
+
+	switch (field->operator) {
+	case FIELD_OP_MINUS:
+		strcat(expr, "-");
+		break;
+	case FIELD_OP_PLUS:
+		strcat(expr, "+");
+		break;
+	default:
+		kfree(expr);
+		return NULL;
+	}
+
+	expr_field_str(field->operands[1], expr);
+
+	return expr;
 }
 
-static const struct tracing_map_ops hist_trigger_elt_comm_ops = {
-	.elt_alloc	= hist_trigger_elt_comm_alloc,
-	.elt_copy	= hist_trigger_elt_comm_copy,
-	.elt_free	= hist_trigger_elt_comm_free,
-	.elt_init	= hist_trigger_elt_comm_init,
-};
+static int contains_operator(char *str)
+{
+	enum field_op_id field_op = FIELD_OP_NONE;
+	char *op;
+
+	op = strpbrk(str, "+-");
+	if (!op)
+		return FIELD_OP_NONE;
+
+	switch (*op) {
+	case '-':
+		if (*str == '-')
+			field_op = FIELD_OP_UNARY_MINUS;
+		else
+			field_op = FIELD_OP_MINUS;
+		break;
+	case '+':
+		field_op = FIELD_OP_PLUS;
+		break;
+	default:
+		break;
+	}
+
+	return field_op;
+}
 
 static void destroy_hist_field(struct hist_field *hist_field,
 			       unsigned int level)
 {
 	unsigned int i;
 
-	if (level > 2)
+	if (level > 3)
 		return;
 
 	if (!hist_field)
@@ -379,11 +2154,17 @@ static void destroy_hist_field(struct hist_field *hist_field,
 	for (i = 0; i < HIST_FIELD_OPERANDS_MAX; i++)
 		destroy_hist_field(hist_field->operands[i], level + 1);
 
+	kfree(hist_field->var.name);
+	kfree(hist_field->name);
+	kfree(hist_field->type);
+
 	kfree(hist_field);
 }
 
-static struct hist_field *create_hist_field(struct ftrace_event_field *field,
-					    unsigned long flags)
+static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
+					    struct ftrace_event_field *field,
+					    unsigned long flags,
+					    char *var_name)
 {
 	struct hist_field *hist_field;
 
@@ -394,8 +2175,22 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
 	if (!hist_field)
 		return NULL;
 
+	hist_field->hist_data = hist_data;
+
+	if (flags & HIST_FIELD_FL_EXPR || flags & HIST_FIELD_FL_ALIAS)
+		goto out; /* caller will populate */
+
+	if (flags & HIST_FIELD_FL_VAR_REF) {
+		hist_field->fn = hist_field_var_ref;
+		goto out;
+	}
+
 	if (flags & HIST_FIELD_FL_HITCOUNT) {
 		hist_field->fn = hist_field_counter;
+		hist_field->size = sizeof(u64);
+		hist_field->type = kstrdup("u64", GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
 		goto out;
 	}
 
@@ -407,8 +2202,29 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
 	if (flags & HIST_FIELD_FL_LOG2) {
 		unsigned long fl = flags & ~HIST_FIELD_FL_LOG2;
 		hist_field->fn = hist_field_log2;
-		hist_field->operands[0] = create_hist_field(field, fl);
+		hist_field->operands[0] = create_hist_field(hist_data, field, fl, NULL);
 		hist_field->size = hist_field->operands[0]->size;
+		hist_field->type = kstrdup(hist_field->operands[0]->type, GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
+		goto out;
+	}
+
+	if (flags & HIST_FIELD_FL_TIMESTAMP) {
+		hist_field->fn = hist_field_timestamp;
+		hist_field->size = sizeof(u64);
+		hist_field->type = kstrdup("u64", GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
+		goto out;
+	}
+
+	if (flags & HIST_FIELD_FL_CPU) {
+		hist_field->fn = hist_field_cpu;
+		hist_field->size = sizeof(int);
+		hist_field->type = kstrdup("unsigned int", GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
 		goto out;
 	}
 
@@ -418,6 +2234,11 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
 	if (is_string_field(field)) {
 		flags |= HIST_FIELD_FL_STRING;
 
+		hist_field->size = MAX_FILTER_STR_VAL;
+		hist_field->type = kstrdup(field->type, GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
+
 		if (field->filter_type == FILTER_STATIC_STRING)
 			hist_field->fn = hist_field_string;
 		else if (field->filter_type == FILTER_DYN_STRING)
@@ -425,6 +2246,12 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
 		else
 			hist_field->fn = hist_field_pstring;
 	} else {
+		hist_field->size = field->size;
+		hist_field->is_signed = field->is_signed;
+		hist_field->type = kstrdup(field->type, GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
+
 		hist_field->fn = select_value_fn(field->size,
 						 field->is_signed);
 		if (!hist_field->fn) {
@@ -436,14 +2263,23 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
 	hist_field->field = field;
 	hist_field->flags = flags;
 
+	if (var_name) {
+		hist_field->var.name = kstrdup(var_name, GFP_KERNEL);
+		if (!hist_field->var.name)
+			goto free;
+	}
+
 	return hist_field;
+ free:
+	destroy_hist_field(hist_field, 0);
+	return NULL;
 }
 
 static void destroy_hist_fields(struct hist_trigger_data *hist_data)
 {
 	unsigned int i;
 
-	for (i = 0; i < TRACING_MAP_FIELDS_MAX; i++) {
+	for (i = 0; i < HIST_FIELDS_MAX; i++) {
 		if (hist_data->fields[i]) {
 			destroy_hist_field(hist_data->fields[i], 0);
 			hist_data->fields[i] = NULL;
@@ -451,69 +2287,1610 @@ static void destroy_hist_fields(struct hist_trigger_data *hist_data)
 	}
 }
 
-static int create_hitcount_val(struct hist_trigger_data *hist_data)
+static int init_var_ref(struct hist_field *ref_field,
+			struct hist_field *var_field,
+			char *system, char *event_name)
 {
-	hist_data->fields[HITCOUNT_IDX] =
-		create_hist_field(NULL, HIST_FIELD_FL_HITCOUNT);
-	if (!hist_data->fields[HITCOUNT_IDX])
-		return -ENOMEM;
+	int err = 0;
+
+	ref_field->var.idx = var_field->var.idx;
+	ref_field->var.hist_data = var_field->hist_data;
+	ref_field->size = var_field->size;
+	ref_field->is_signed = var_field->is_signed;
+	ref_field->flags |= var_field->flags &
+		(HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);
+
+	if (system) {
+		ref_field->system = kstrdup(system, GFP_KERNEL);
+		if (!ref_field->system)
+			return -ENOMEM;
+	}
 
-	hist_data->n_vals++;
+	if (event_name) {
+		ref_field->event_name = kstrdup(event_name, GFP_KERNEL);
+		if (!ref_field->event_name) {
+			err = -ENOMEM;
+			goto free;
+		}
+	}
 
-	if (WARN_ON(hist_data->n_vals > TRACING_MAP_VALS_MAX))
+	if (var_field->var.name) {
+		ref_field->name = kstrdup(var_field->var.name, GFP_KERNEL);
+		if (!ref_field->name) {
+			err = -ENOMEM;
+			goto free;
+		}
+	} else if (var_field->name) {
+		ref_field->name = kstrdup(var_field->name, GFP_KERNEL);
+		if (!ref_field->name) {
+			err = -ENOMEM;
+			goto free;
+		}
+	}
+
+	ref_field->type = kstrdup(var_field->type, GFP_KERNEL);
+	if (!ref_field->type) {
+		err = -ENOMEM;
+		goto free;
+	}
+ out:
+	return err;
+ free:
+	kfree(ref_field->system);
+	kfree(ref_field->event_name);
+	kfree(ref_field->name);
+
+	goto out;
+}
+
+static struct hist_field *create_var_ref(struct hist_field *var_field,
+					 char *system, char *event_name)
+{
+	unsigned long flags = HIST_FIELD_FL_VAR_REF;
+	struct hist_field *ref_field;
+
+	ref_field = create_hist_field(var_field->hist_data, NULL, flags, NULL);
+	if (ref_field) {
+		if (init_var_ref(ref_field, var_field, system, event_name)) {
+			destroy_hist_field(ref_field, 0);
+			return NULL;
+		}
+	}
+
+	return ref_field;
+}
+
+static bool is_var_ref(char *var_name)
+{
+	if (!var_name || strlen(var_name) < 2 || var_name[0] != '$')
+		return false;
+
+	return true;
+}
+
+static char *field_name_from_var(struct hist_trigger_data *hist_data,
+				 char *var_name)
+{
+	char *name, *field;
+	unsigned int i;
+
+	for (i = 0; i < hist_data->attrs->var_defs.n_vars; i++) {
+		name = hist_data->attrs->var_defs.name[i];
+
+		if (strcmp(var_name, name) == 0) {
+			field = hist_data->attrs->var_defs.expr[i];
+			if (contains_operator(field) || is_var_ref(field))
+				continue;
+			return field;
+		}
+	}
+
+	return NULL;
+}
+
+static char *local_field_var_ref(struct hist_trigger_data *hist_data,
+				 char *system, char *event_name,
+				 char *var_name)
+{
+	struct trace_event_call *call;
+
+	if (system && event_name) {
+		call = hist_data->event_file->event_call;
+
+		if (strcmp(system, call->class->system) != 0)
+			return NULL;
+
+		if (strcmp(event_name, trace_event_name(call)) != 0)
+			return NULL;
+	}
+
+	if (!!system != !!event_name)
+		return NULL;
+
+	if (!is_var_ref(var_name))
+		return NULL;
+
+	var_name++;
+
+	return field_name_from_var(hist_data, var_name);
+}
+
+static struct hist_field *parse_var_ref(struct hist_trigger_data *hist_data,
+					char *system, char *event_name,
+					char *var_name)
+{
+	struct hist_field *var_field = NULL, *ref_field = NULL;
+
+	if (!is_var_ref(var_name))
+		return NULL;
+
+	var_name++;
+
+	var_field = find_event_var(hist_data, system, event_name, var_name);
+	if (var_field)
+		ref_field = create_var_ref(var_field, system, event_name);
+
+	if (!ref_field)
+		hist_err_event("Couldn't find variable: $",
+			       system, event_name, var_name);
+
+	return ref_field;
+}
+
+static struct ftrace_event_field *
+parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file,
+	    char *field_str, unsigned long *flags)
+{
+	struct ftrace_event_field *field = NULL;
+	char *field_name, *modifier, *str;
+
+	modifier = str = kstrdup(field_str, GFP_KERNEL);
+	if (!modifier)
+		return ERR_PTR(-ENOMEM);
+
+	field_name = strsep(&modifier, ".");
+	if (modifier) {
+		if (strcmp(modifier, "hex") == 0)
+			*flags |= HIST_FIELD_FL_HEX;
+		else if (strcmp(modifier, "sym") == 0)
+			*flags |= HIST_FIELD_FL_SYM;
+		else if (strcmp(modifier, "sym-offset") == 0)
+			*flags |= HIST_FIELD_FL_SYM_OFFSET;
+		else if ((strcmp(modifier, "execname") == 0) &&
+			 (strcmp(field_name, "common_pid") == 0))
+			*flags |= HIST_FIELD_FL_EXECNAME;
+		else if (strcmp(modifier, "syscall") == 0)
+			*flags |= HIST_FIELD_FL_SYSCALL;
+		else if (strcmp(modifier, "log2") == 0)
+			*flags |= HIST_FIELD_FL_LOG2;
+		else if (strcmp(modifier, "usecs") == 0)
+			*flags |= HIST_FIELD_FL_TIMESTAMP_USECS;
+		else {
+			field = ERR_PTR(-EINVAL);
+			goto out;
+		}
+	}
+
+	if (strcmp(field_name, "common_timestamp") == 0) {
+		*flags |= HIST_FIELD_FL_TIMESTAMP;
+		hist_data->enable_timestamps = true;
+		if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS)
+			hist_data->attrs->ts_in_usecs = true;
+	} else if (strcmp(field_name, "cpu") == 0)
+		*flags |= HIST_FIELD_FL_CPU;
+	else {
+		field = trace_find_event_field(file->event_call, field_name);
+		if (!field || !field->size) {
+			field = ERR_PTR(-EINVAL);
+			goto out;
+		}
+	}
+ out:
+	kfree(str);
+
+	return field;
+}
+
+static struct hist_field *create_alias(struct hist_trigger_data *hist_data,
+				       struct hist_field *var_ref,
+				       char *var_name)
+{
+	struct hist_field *alias = NULL;
+	unsigned long flags = HIST_FIELD_FL_ALIAS | HIST_FIELD_FL_VAR;
+
+	alias = create_hist_field(hist_data, NULL, flags, var_name);
+	if (!alias)
+		return NULL;
+
+	alias->fn = var_ref->fn;
+	alias->operands[0] = var_ref;
+
+	if (init_var_ref(alias, var_ref, var_ref->system, var_ref->event_name)) {
+		destroy_hist_field(alias, 0);
+		return NULL;
+	}
+
+	return alias;
+}
+
+static struct hist_field *parse_atom(struct hist_trigger_data *hist_data,
+				     struct trace_event_file *file, char *str,
+				     unsigned long *flags, char *var_name)
+{
+	char *s, *ref_system = NULL, *ref_event = NULL, *ref_var = str;
+	struct ftrace_event_field *field = NULL;
+	struct hist_field *hist_field = NULL;
+	int ret = 0;
+
+	s = strchr(str, '.');
+	if (s) {
+		s = strchr(++s, '.');
+		if (s) {
+			ref_system = strsep(&str, ".");
+			if (!str) {
+				ret = -EINVAL;
+				goto out;
+			}
+			ref_event = strsep(&str, ".");
+			if (!str) {
+				ret = -EINVAL;
+				goto out;
+			}
+			ref_var = str;
+		}
+	}
+
+	s = local_field_var_ref(hist_data, ref_system, ref_event, ref_var);
+	if (!s) {
+		hist_field = parse_var_ref(hist_data, ref_system, ref_event, ref_var);
+		if (hist_field) {
+			hist_data->var_refs[hist_data->n_var_refs] = hist_field;
+			hist_field->var_ref_idx = hist_data->n_var_refs++;
+			if (var_name) {
+				hist_field = create_alias(hist_data, hist_field, var_name);
+				if (!hist_field) {
+					ret = -ENOMEM;
+					goto out;
+				}
+			}
+			return hist_field;
+		}
+	} else
+		str = s;
+
+	field = parse_field(hist_data, file, str, flags);
+	if (IS_ERR(field)) {
+		ret = PTR_ERR(field);
+		goto out;
+	}
+
+	hist_field = create_hist_field(hist_data, field, *flags, var_name);
+	if (!hist_field) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	return hist_field;
+ out:
+	return ERR_PTR(ret);
+}
+
+static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
+				     struct trace_event_file *file,
+				     char *str, unsigned long flags,
+				     char *var_name, unsigned int level);
+
+static struct hist_field *parse_unary(struct hist_trigger_data *hist_data,
+				      struct trace_event_file *file,
+				      char *str, unsigned long flags,
+				      char *var_name, unsigned int level)
+{
+	struct hist_field *operand1, *expr = NULL;
+	unsigned long operand_flags;
+	int ret = 0;
+	char *s;
+
+	/* we support only -(xxx) i.e. explicit parens required */
+
+	if (level > 3) {
+		hist_err("Too many subexpressions (3 max): ", str);
+		ret = -EINVAL;
+		goto free;
+	}
+
+	str++; /* skip leading '-' */
+
+	s = strchr(str, '(');
+	if (s)
+		str++;
+	else {
+		ret = -EINVAL;
+		goto free;
+	}
+
+	s = strrchr(str, ')');
+	if (s)
+		*s = '\0';
+	else {
+		ret = -EINVAL; /* no closing ')' */
+		goto free;
+	}
+
+	flags |= HIST_FIELD_FL_EXPR;
+	expr = create_hist_field(hist_data, NULL, flags, var_name);
+	if (!expr) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	operand_flags = 0;
+	operand1 = parse_expr(hist_data, file, str, operand_flags, NULL, ++level);
+	if (IS_ERR(operand1)) {
+		ret = PTR_ERR(operand1);
+		goto free;
+	}
+
+	expr->flags |= operand1->flags &
+		(HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);
+	expr->fn = hist_field_unary_minus;
+	expr->operands[0] = operand1;
+	expr->operator = FIELD_OP_UNARY_MINUS;
+	expr->name = expr_str(expr, 0);
+	expr->type = kstrdup(operand1->type, GFP_KERNEL);
+	if (!expr->type) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	return expr;
+ free:
+	destroy_hist_field(expr, 0);
+	return ERR_PTR(ret);
+}
+
+static int check_expr_operands(struct hist_field *operand1,
+			       struct hist_field *operand2)
+{
+	unsigned long operand1_flags = operand1->flags;
+	unsigned long operand2_flags = operand2->flags;
+
+	if ((operand1_flags & HIST_FIELD_FL_VAR_REF) ||
+	    (operand1_flags & HIST_FIELD_FL_ALIAS)) {
+		struct hist_field *var;
+
+		var = find_var_field(operand1->var.hist_data, operand1->name);
+		if (!var)
+			return -EINVAL;
+		operand1_flags = var->flags;
+	}
+
+	if ((operand2_flags & HIST_FIELD_FL_VAR_REF) ||
+	    (operand2_flags & HIST_FIELD_FL_ALIAS)) {
+		struct hist_field *var;
+
+		var = find_var_field(operand2->var.hist_data, operand2->name);
+		if (!var)
+			return -EINVAL;
+		operand2_flags = var->flags;
+	}
+
+	if ((operand1_flags & HIST_FIELD_FL_TIMESTAMP_USECS) !=
+	    (operand2_flags & HIST_FIELD_FL_TIMESTAMP_USECS)) {
+		hist_err("Timestamp units in expression don't match", NULL);
 		return -EINVAL;
+	}
 
 	return 0;
 }
 
-static int create_val_field(struct hist_trigger_data *hist_data,
-			    unsigned int val_idx,
-			    struct trace_event_file *file,
-			    char *field_str)
+static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
+				     struct trace_event_file *file,
+				     char *str, unsigned long flags,
+				     char *var_name, unsigned int level)
 {
-	struct ftrace_event_field *field = NULL;
-	unsigned long flags = 0;
-	char *field_name;
+	struct hist_field *operand1 = NULL, *operand2 = NULL, *expr = NULL;
+	unsigned long operand_flags;
+	int field_op, ret = -EINVAL;
+	char *sep, *operand1_str;
+
+	if (level > 3) {
+		hist_err("Too many subexpressions (3 max): ", str);
+		return ERR_PTR(-EINVAL);
+	}
+
+	field_op = contains_operator(str);
+
+	if (field_op == FIELD_OP_NONE)
+		return parse_atom(hist_data, file, str, &flags, var_name);
+
+	if (field_op == FIELD_OP_UNARY_MINUS)
+		return parse_unary(hist_data, file, str, flags, var_name, ++level);
+
+	switch (field_op) {
+	case FIELD_OP_MINUS:
+		sep = "-";
+		break;
+	case FIELD_OP_PLUS:
+		sep = "+";
+		break;
+	default:
+		goto free;
+	}
+
+	operand1_str = strsep(&str, sep);
+	if (!operand1_str || !str)
+		goto free;
+
+	operand_flags = 0;
+	operand1 = parse_atom(hist_data, file, operand1_str,
+			      &operand_flags, NULL);
+	if (IS_ERR(operand1)) {
+		ret = PTR_ERR(operand1);
+		operand1 = NULL;
+		goto free;
+	}
+
+	/* rest of string could be another expression e.g. b+c in a+b+c */
+	operand_flags = 0;
+	operand2 = parse_expr(hist_data, file, str, operand_flags, NULL, ++level);
+	if (IS_ERR(operand2)) {
+		ret = PTR_ERR(operand2);
+		operand2 = NULL;
+		goto free;
+	}
+
+	ret = check_expr_operands(operand1, operand2);
+	if (ret)
+		goto free;
+
+	flags |= HIST_FIELD_FL_EXPR;
+
+	flags |= operand1->flags &
+		(HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);
+
+	expr = create_hist_field(hist_data, NULL, flags, var_name);
+	if (!expr) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	operand1->read_once = true;
+	operand2->read_once = true;
+
+	expr->operands[0] = operand1;
+	expr->operands[1] = operand2;
+	expr->operator = field_op;
+	expr->name = expr_str(expr, 0);
+	expr->type = kstrdup(operand1->type, GFP_KERNEL);
+	if (!expr->type) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	switch (field_op) {
+	case FIELD_OP_MINUS:
+		expr->fn = hist_field_minus;
+		break;
+	case FIELD_OP_PLUS:
+		expr->fn = hist_field_plus;
+		break;
+	default:
+		ret = -EINVAL;
+		goto free;
+	}
+
+	return expr;
+ free:
+	destroy_hist_field(operand1, 0);
+	destroy_hist_field(operand2, 0);
+	destroy_hist_field(expr, 0);
+
+	return ERR_PTR(ret);
+}
+
+static char *find_trigger_filter(struct hist_trigger_data *hist_data,
+				 struct trace_event_file *file)
+{
+	struct event_trigger_data *test;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			if (test->private_data == hist_data)
+				return test->filter_str;
+		}
+	}
+
+	return NULL;
+}
+
+static struct event_command trigger_hist_cmd;
+static int event_hist_trigger_func(struct event_command *cmd_ops,
+				   struct trace_event_file *file,
+				   char *glob, char *cmd, char *param);
+
+static bool compatible_keys(struct hist_trigger_data *target_hist_data,
+			    struct hist_trigger_data *hist_data,
+			    unsigned int n_keys)
+{
+	struct hist_field *target_hist_field, *hist_field;
+	unsigned int n, i, j;
+
+	if (hist_data->n_fields - hist_data->n_vals != n_keys)
+		return false;
+
+	i = hist_data->n_vals;
+	j = target_hist_data->n_vals;
+
+	for (n = 0; n < n_keys; n++) {
+		hist_field = hist_data->fields[i + n];
+		target_hist_field = target_hist_data->fields[j + n];
+
+		if (strcmp(hist_field->type, target_hist_field->type) != 0)
+			return false;
+		if (hist_field->size != target_hist_field->size)
+			return false;
+		if (hist_field->is_signed != target_hist_field->is_signed)
+			return false;
+	}
+
+	return true;
+}
+
+static struct hist_trigger_data *
+find_compatible_hist(struct hist_trigger_data *target_hist_data,
+		     struct trace_event_file *file)
+{
+	struct hist_trigger_data *hist_data;
+	struct event_trigger_data *test;
+	unsigned int n_keys;
+
+	n_keys = target_hist_data->n_fields - target_hist_data->n_vals;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			hist_data = test->private_data;
+
+			if (compatible_keys(target_hist_data, hist_data, n_keys))
+				return hist_data;
+		}
+	}
+
+	return NULL;
+}
+
+static struct trace_event_file *event_file(struct trace_array *tr,
+					   char *system, char *event_name)
+{
+	struct trace_event_file *file;
+
+	file = find_event_file(tr, system, event_name);
+	if (!file)
+		return ERR_PTR(-EINVAL);
+
+	return file;
+}
+
+static struct hist_field *
+find_synthetic_field_var(struct hist_trigger_data *target_hist_data,
+			 char *system, char *event_name, char *field_name)
+{
+	struct hist_field *event_var;
+	char *synthetic_name;
+
+	synthetic_name = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL);
+	if (!synthetic_name)
+		return ERR_PTR(-ENOMEM);
+
+	strcpy(synthetic_name, "synthetic_");
+	strcat(synthetic_name, field_name);
+
+	event_var = find_event_var(target_hist_data, system, event_name, synthetic_name);
+
+	kfree(synthetic_name);
+
+	return event_var;
+}
+
+/**
+ * create_field_var_hist - Automatically create a histogram and var for a field
+ * @target_hist_data: The target hist trigger
+ * @subsys_name: Optional subsystem name
+ * @event_name: Optional event name
+ * @field_name: The name of the field (and the resulting variable)
+ *
+ * Hist trigger actions fetch data from variables, not directly from
+ * events.  However, for convenience, users are allowed to directly
+ * specify an event field in an action, which will be automatically
+ * converted into a variable on their behalf.
+
+ * If a user specifies a field on an event that isn't the event the
+ * histogram currently being defined (the target event histogram), the
+ * only way that can be accomplished is if a new hist trigger is
+ * created and the field variable defined on that.
+ *
+ * This function creates a new histogram compatible with the target
+ * event (meaning a histogram with the same key as the target
+ * histogram), and creates a variable for the specified field, but
+ * with 'synthetic_' prepended to the variable name in order to avoid
+ * collision with normal field variables.
+ *
+ * Return: The variable created for the field.
+ */
+static struct hist_field *
+create_field_var_hist(struct hist_trigger_data *target_hist_data,
+		      char *subsys_name, char *event_name, char *field_name)
+{
+	struct trace_array *tr = target_hist_data->event_file->tr;
+	struct hist_field *event_var = ERR_PTR(-EINVAL);
+	struct hist_trigger_data *hist_data;
+	unsigned int i, n, first = true;
+	struct field_var_hist *var_hist;
+	struct trace_event_file *file;
+	struct hist_field *key_field;
+	char *saved_filter;
+	char *cmd;
+	int ret;
+
+	if (target_hist_data->n_field_var_hists >= SYNTH_FIELDS_MAX) {
+		hist_err_event("onmatch: Too many field variables defined: ",
+			       subsys_name, event_name, field_name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	file = event_file(tr, subsys_name, event_name);
+
+	if (IS_ERR(file)) {
+		hist_err_event("onmatch: Event file not found: ",
+			       subsys_name, event_name, field_name);
+		ret = PTR_ERR(file);
+		return ERR_PTR(ret);
+	}
+
+	/*
+	 * Look for a histogram compatible with target.  We'll use the
+	 * found histogram specification to create a new matching
+	 * histogram with our variable on it.  target_hist_data is not
+	 * yet a registered histogram so we can't use that.
+	 */
+	hist_data = find_compatible_hist(target_hist_data, file);
+	if (!hist_data) {
+		hist_err_event("onmatch: Matching event histogram not found: ",
+			       subsys_name, event_name, field_name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	/* See if a synthetic field variable has already been created */
+	event_var = find_synthetic_field_var(target_hist_data, subsys_name,
+					     event_name, field_name);
+	if (!IS_ERR_OR_NULL(event_var))
+		return event_var;
+
+	var_hist = kzalloc(sizeof(*var_hist), GFP_KERNEL);
+	if (!var_hist)
+		return ERR_PTR(-ENOMEM);
+
+	cmd = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL);
+	if (!cmd) {
+		kfree(var_hist);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	/* Use the same keys as the compatible histogram */
+	strcat(cmd, "keys=");
+
+	for_each_hist_key_field(i, hist_data) {
+		key_field = hist_data->fields[i];
+		if (!first)
+			strcat(cmd, ",");
+		strcat(cmd, key_field->field->name);
+		first = false;
+	}
+
+	/* Create the synthetic field variable specification */
+	strcat(cmd, ":synthetic_");
+	strcat(cmd, field_name);
+	strcat(cmd, "=");
+	strcat(cmd, field_name);
+
+	/* Use the same filter as the compatible histogram */
+	saved_filter = find_trigger_filter(hist_data, file);
+	if (saved_filter) {
+		strcat(cmd, " if ");
+		strcat(cmd, saved_filter);
+	}
+
+	var_hist->cmd = kstrdup(cmd, GFP_KERNEL);
+	if (!var_hist->cmd) {
+		kfree(cmd);
+		kfree(var_hist);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	/* Save the compatible histogram information */
+	var_hist->hist_data = hist_data;
+
+	/* Create the new histogram with our variable */
+	ret = event_hist_trigger_func(&trigger_hist_cmd, file,
+				      "", "hist", cmd);
+	if (ret) {
+		kfree(cmd);
+		kfree(var_hist->cmd);
+		kfree(var_hist);
+		hist_err_event("onmatch: Couldn't create histogram for field: ",
+			       subsys_name, event_name, field_name);
+		return ERR_PTR(ret);
+	}
+
+	kfree(cmd);
+
+	/* If we can't find the variable, something went wrong */
+	event_var = find_synthetic_field_var(target_hist_data, subsys_name,
+					     event_name, field_name);
+	if (IS_ERR_OR_NULL(event_var)) {
+		kfree(var_hist->cmd);
+		kfree(var_hist);
+		hist_err_event("onmatch: Couldn't find synthetic variable: ",
+			       subsys_name, event_name, field_name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	n = target_hist_data->n_field_var_hists;
+	target_hist_data->field_var_hists[n] = var_hist;
+	target_hist_data->n_field_var_hists++;
+
+	return event_var;
+}
+
+static struct hist_field *
+find_target_event_var(struct hist_trigger_data *hist_data,
+		      char *subsys_name, char *event_name, char *var_name)
+{
+	struct trace_event_file *file = hist_data->event_file;
+	struct hist_field *hist_field = NULL;
+
+	if (subsys_name) {
+		struct trace_event_call *call;
+
+		if (!event_name)
+			return NULL;
+
+		call = file->event_call;
+
+		if (strcmp(subsys_name, call->class->system) != 0)
+			return NULL;
+
+		if (strcmp(event_name, trace_event_name(call)) != 0)
+			return NULL;
+	}
+
+	hist_field = find_var_field(hist_data, var_name);
+
+	return hist_field;
+}
+
+static inline void __update_field_vars(struct tracing_map_elt *elt,
+				       struct ring_buffer_event *rbe,
+				       void *rec,
+				       struct field_var **field_vars,
+				       unsigned int n_field_vars,
+				       unsigned int field_var_str_start)
+{
+	struct hist_elt_data *elt_data = elt->private_data;
+	unsigned int i, j, var_idx;
+	u64 var_val;
+
+	for (i = 0, j = field_var_str_start; i < n_field_vars; i++) {
+		struct field_var *field_var = field_vars[i];
+		struct hist_field *var = field_var->var;
+		struct hist_field *val = field_var->val;
+
+		var_val = val->fn(val, elt, rbe, rec);
+		var_idx = var->var.idx;
+
+		if (val->flags & HIST_FIELD_FL_STRING) {
+			char *str = elt_data->field_var_str[j++];
+			char *val_str = (char *)(uintptr_t)var_val;
+
+			strscpy(str, val_str, STR_VAR_LEN_MAX);
+			var_val = (u64)(uintptr_t)str;
+		}
+		tracing_map_set_var(elt, var_idx, var_val);
+	}
+}
+
+static void update_field_vars(struct hist_trigger_data *hist_data,
+			      struct tracing_map_elt *elt,
+			      struct ring_buffer_event *rbe,
+			      void *rec)
+{
+	__update_field_vars(elt, rbe, rec, hist_data->field_vars,
+			    hist_data->n_field_vars, 0);
+}
+
+static void update_max_vars(struct hist_trigger_data *hist_data,
+			    struct tracing_map_elt *elt,
+			    struct ring_buffer_event *rbe,
+			    void *rec)
+{
+	__update_field_vars(elt, rbe, rec, hist_data->max_vars,
+			    hist_data->n_max_vars, hist_data->n_field_var_str);
+}
+
+static struct hist_field *create_var(struct hist_trigger_data *hist_data,
+				     struct trace_event_file *file,
+				     char *name, int size, const char *type)
+{
+	struct hist_field *var;
+	int idx;
+
+	if (find_var(hist_data, file, name) && !hist_data->remove) {
+		var = ERR_PTR(-EINVAL);
+		goto out;
+	}
+
+	var = kzalloc(sizeof(struct hist_field), GFP_KERNEL);
+	if (!var) {
+		var = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+
+	idx = tracing_map_add_var(hist_data->map);
+	if (idx < 0) {
+		kfree(var);
+		var = ERR_PTR(-EINVAL);
+		goto out;
+	}
+
+	var->flags = HIST_FIELD_FL_VAR;
+	var->var.idx = idx;
+	var->var.hist_data = var->hist_data = hist_data;
+	var->size = size;
+	var->var.name = kstrdup(name, GFP_KERNEL);
+	var->type = kstrdup(type, GFP_KERNEL);
+	if (!var->var.name || !var->type) {
+		kfree(var->var.name);
+		kfree(var->type);
+		kfree(var);
+		var = ERR_PTR(-ENOMEM);
+	}
+ out:
+	return var;
+}
+
+static struct field_var *create_field_var(struct hist_trigger_data *hist_data,
+					  struct trace_event_file *file,
+					  char *field_name)
+{
+	struct hist_field *val = NULL, *var = NULL;
+	unsigned long flags = HIST_FIELD_FL_VAR;
+	struct field_var *field_var;
 	int ret = 0;
 
-	if (WARN_ON(val_idx >= TRACING_MAP_VALS_MAX))
+	if (hist_data->n_field_vars >= SYNTH_FIELDS_MAX) {
+		hist_err("Too many field variables defined: ", field_name);
+		ret = -EINVAL;
+		goto err;
+	}
+
+	val = parse_atom(hist_data, file, field_name, &flags, NULL);
+	if (IS_ERR(val)) {
+		hist_err("Couldn't parse field variable: ", field_name);
+		ret = PTR_ERR(val);
+		goto err;
+	}
+
+	var = create_var(hist_data, file, field_name, val->size, val->type);
+	if (IS_ERR(var)) {
+		hist_err("Couldn't create or find variable: ", field_name);
+		kfree(val);
+		ret = PTR_ERR(var);
+		goto err;
+	}
+
+	field_var = kzalloc(sizeof(struct field_var), GFP_KERNEL);
+	if (!field_var) {
+		kfree(val);
+		kfree(var);
+		ret =  -ENOMEM;
+		goto err;
+	}
+
+	field_var->var = var;
+	field_var->val = val;
+ out:
+	return field_var;
+ err:
+	field_var = ERR_PTR(ret);
+	goto out;
+}
+
+/**
+ * create_target_field_var - Automatically create a variable for a field
+ * @target_hist_data: The target hist trigger
+ * @subsys_name: Optional subsystem name
+ * @event_name: Optional event name
+ * @var_name: The name of the field (and the resulting variable)
+ *
+ * Hist trigger actions fetch data from variables, not directly from
+ * events.  However, for convenience, users are allowed to directly
+ * specify an event field in an action, which will be automatically
+ * converted into a variable on their behalf.
+
+ * This function creates a field variable with the name var_name on
+ * the hist trigger currently being defined on the target event.  If
+ * subsys_name and event_name are specified, this function simply
+ * verifies that they do in fact match the target event subsystem and
+ * event name.
+ *
+ * Return: The variable created for the field.
+ */
+static struct field_var *
+create_target_field_var(struct hist_trigger_data *target_hist_data,
+			char *subsys_name, char *event_name, char *var_name)
+{
+	struct trace_event_file *file = target_hist_data->event_file;
+
+	if (subsys_name) {
+		struct trace_event_call *call;
+
+		if (!event_name)
+			return NULL;
+
+		call = file->event_call;
+
+		if (strcmp(subsys_name, call->class->system) != 0)
+			return NULL;
+
+		if (strcmp(event_name, trace_event_name(call)) != 0)
+			return NULL;
+	}
+
+	return create_field_var(target_hist_data, file, var_name);
+}
+
+static void onmax_print(struct seq_file *m,
+			struct hist_trigger_data *hist_data,
+			struct tracing_map_elt *elt,
+			struct action_data *data)
+{
+	unsigned int i, save_var_idx, max_idx = data->onmax.max_var->var.idx;
+
+	seq_printf(m, "\n\tmax: %10llu", tracing_map_read_var(elt, max_idx));
+
+	for (i = 0; i < hist_data->n_max_vars; i++) {
+		struct hist_field *save_val = hist_data->max_vars[i]->val;
+		struct hist_field *save_var = hist_data->max_vars[i]->var;
+		u64 val;
+
+		save_var_idx = save_var->var.idx;
+
+		val = tracing_map_read_var(elt, save_var_idx);
+
+		if (save_val->flags & HIST_FIELD_FL_STRING) {
+			seq_printf(m, "  %s: %-32s", save_var->var.name,
+				   (char *)(uintptr_t)(val));
+		} else
+			seq_printf(m, "  %s: %10llu", save_var->var.name, val);
+	}
+}
+
+static void onmax_save(struct hist_trigger_data *hist_data,
+		       struct tracing_map_elt *elt, void *rec,
+		       struct ring_buffer_event *rbe,
+		       struct action_data *data, u64 *var_ref_vals)
+{
+	unsigned int max_idx = data->onmax.max_var->var.idx;
+	unsigned int max_var_ref_idx = data->onmax.max_var_ref_idx;
+
+	u64 var_val, max_val;
+
+	var_val = var_ref_vals[max_var_ref_idx];
+	max_val = tracing_map_read_var(elt, max_idx);
+
+	if (var_val <= max_val)
+		return;
+
+	tracing_map_set_var(elt, max_idx, var_val);
+
+	update_max_vars(hist_data, elt, rbe, rec);
+}
+
+static void onmax_destroy(struct action_data *data)
+{
+	unsigned int i;
+
+	destroy_hist_field(data->onmax.max_var, 0);
+	destroy_hist_field(data->onmax.var, 0);
+
+	kfree(data->onmax.var_str);
+	kfree(data->onmax.fn_name);
+
+	for (i = 0; i < data->n_params; i++)
+		kfree(data->params[i]);
+
+	kfree(data);
+}
+
+static int onmax_create(struct hist_trigger_data *hist_data,
+			struct action_data *data)
+{
+	struct trace_event_file *file = hist_data->event_file;
+	struct hist_field *var_field, *ref_field, *max_var;
+	unsigned int var_ref_idx = hist_data->n_var_refs;
+	struct field_var *field_var;
+	char *onmax_var_str, *param;
+	unsigned long flags;
+	unsigned int i;
+	int ret = 0;
+
+	onmax_var_str = data->onmax.var_str;
+	if (onmax_var_str[0] != '$') {
+		hist_err("onmax: For onmax(x), x must be a variable: ", onmax_var_str);
 		return -EINVAL;
+	}
+	onmax_var_str++;
 
-	field_name = strsep(&field_str, ".");
-	if (field_str) {
-		if (strcmp(field_str, "hex") == 0)
-			flags |= HIST_FIELD_FL_HEX;
-		else {
+	var_field = find_target_event_var(hist_data, NULL, NULL, onmax_var_str);
+	if (!var_field) {
+		hist_err("onmax: Couldn't find onmax variable: ", onmax_var_str);
+		return -EINVAL;
+	}
+
+	flags = HIST_FIELD_FL_VAR_REF;
+	ref_field = create_hist_field(hist_data, NULL, flags, NULL);
+	if (!ref_field)
+		return -ENOMEM;
+
+	if (init_var_ref(ref_field, var_field, NULL, NULL)) {
+		destroy_hist_field(ref_field, 0);
+		ret = -ENOMEM;
+		goto out;
+	}
+	hist_data->var_refs[hist_data->n_var_refs] = ref_field;
+	ref_field->var_ref_idx = hist_data->n_var_refs++;
+	data->onmax.var = ref_field;
+
+	data->fn = onmax_save;
+	data->onmax.max_var_ref_idx = var_ref_idx;
+	max_var = create_var(hist_data, file, "max", sizeof(u64), "u64");
+	if (IS_ERR(max_var)) {
+		hist_err("onmax: Couldn't create onmax variable: ", "max");
+		ret = PTR_ERR(max_var);
+		goto out;
+	}
+	data->onmax.max_var = max_var;
+
+	for (i = 0; i < data->n_params; i++) {
+		param = kstrdup(data->params[i], GFP_KERNEL);
+		if (!param) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		field_var = create_target_field_var(hist_data, NULL, NULL, param);
+		if (IS_ERR(field_var)) {
+			hist_err("onmax: Couldn't create field variable: ", param);
+			ret = PTR_ERR(field_var);
+			kfree(param);
+			goto out;
+		}
+
+		hist_data->max_vars[hist_data->n_max_vars++] = field_var;
+		if (field_var->val->flags & HIST_FIELD_FL_STRING)
+			hist_data->n_max_var_str++;
+
+		kfree(param);
+	}
+ out:
+	return ret;
+}
+
+static int parse_action_params(char *params, struct action_data *data)
+{
+	char *param, *saved_param;
+	int ret = 0;
+
+	while (params) {
+		if (data->n_params >= SYNTH_FIELDS_MAX)
+			goto out;
+
+		param = strsep(&params, ",");
+		if (!param) {
 			ret = -EINVAL;
 			goto out;
 		}
+
+		param = strstrip(param);
+		if (strlen(param) < 2) {
+			hist_err("Invalid action param: ", param);
+			ret = -EINVAL;
+			goto out;
+		}
+
+		saved_param = kstrdup(param, GFP_KERNEL);
+		if (!saved_param) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		data->params[data->n_params++] = saved_param;
 	}
+ out:
+	return ret;
+}
 
-	field = trace_find_event_field(file->event_call, field_name);
-	if (!field || !field->size) {
+static struct action_data *onmax_parse(char *str)
+{
+	char *onmax_fn_name, *onmax_var_str;
+	struct action_data *data;
+	int ret = -EINVAL;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return ERR_PTR(-ENOMEM);
+
+	onmax_var_str = strsep(&str, ")");
+	if (!onmax_var_str || !str) {
 		ret = -EINVAL;
-		goto out;
+		goto free;
+	}
+
+	data->onmax.var_str = kstrdup(onmax_var_str, GFP_KERNEL);
+	if (!data->onmax.var_str) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	strsep(&str, ".");
+	if (!str)
+		goto free;
+
+	onmax_fn_name = strsep(&str, "(");
+	if (!onmax_fn_name || !str)
+		goto free;
+
+	if (strncmp(onmax_fn_name, "save", strlen("save")) == 0) {
+		char *params = strsep(&str, ")");
+
+		if (!params) {
+			ret = -EINVAL;
+			goto free;
+		}
+
+		ret = parse_action_params(params, data);
+		if (ret)
+			goto free;
+	} else
+		goto free;
+
+	data->onmax.fn_name = kstrdup(onmax_fn_name, GFP_KERNEL);
+	if (!data->onmax.fn_name) {
+		ret = -ENOMEM;
+		goto free;
+	}
+ out:
+	return data;
+ free:
+	onmax_destroy(data);
+	data = ERR_PTR(ret);
+	goto out;
+}
+
+static void onmatch_destroy(struct action_data *data)
+{
+	unsigned int i;
+
+	mutex_lock(&synth_event_mutex);
+
+	kfree(data->onmatch.match_event);
+	kfree(data->onmatch.match_event_system);
+	kfree(data->onmatch.synth_event_name);
+
+	for (i = 0; i < data->n_params; i++)
+		kfree(data->params[i]);
+
+	if (data->onmatch.synth_event)
+		data->onmatch.synth_event->ref--;
+
+	kfree(data);
+
+	mutex_unlock(&synth_event_mutex);
+}
+
+static void destroy_field_var(struct field_var *field_var)
+{
+	if (!field_var)
+		return;
+
+	destroy_hist_field(field_var->var, 0);
+	destroy_hist_field(field_var->val, 0);
+
+	kfree(field_var);
+}
+
+static void destroy_field_vars(struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_field_vars; i++)
+		destroy_field_var(hist_data->field_vars[i]);
+}
+
+static void save_field_var(struct hist_trigger_data *hist_data,
+			   struct field_var *field_var)
+{
+	hist_data->field_vars[hist_data->n_field_vars++] = field_var;
+
+	if (field_var->val->flags & HIST_FIELD_FL_STRING)
+		hist_data->n_field_var_str++;
+}
+
+
+static void destroy_synth_var_refs(struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_synth_var_refs; i++)
+		destroy_hist_field(hist_data->synth_var_refs[i], 0);
+}
+
+static void save_synth_var_ref(struct hist_trigger_data *hist_data,
+			 struct hist_field *var_ref)
+{
+	hist_data->synth_var_refs[hist_data->n_synth_var_refs++] = var_ref;
+
+	hist_data->var_refs[hist_data->n_var_refs] = var_ref;
+	var_ref->var_ref_idx = hist_data->n_var_refs++;
+}
+
+static int check_synth_field(struct synth_event *event,
+			     struct hist_field *hist_field,
+			     unsigned int field_pos)
+{
+	struct synth_field *field;
+
+	if (field_pos >= event->n_fields)
+		return -EINVAL;
+
+	field = event->fields[field_pos];
+
+	if (strcmp(field->type, hist_field->type) != 0)
+		return -EINVAL;
+
+	return 0;
+}
+
+static struct hist_field *
+onmatch_find_var(struct hist_trigger_data *hist_data, struct action_data *data,
+		 char *system, char *event, char *var)
+{
+	struct hist_field *hist_field;
+
+	var++; /* skip '$' */
+
+	hist_field = find_target_event_var(hist_data, system, event, var);
+	if (!hist_field) {
+		if (!system) {
+			system = data->onmatch.match_event_system;
+			event = data->onmatch.match_event;
+		}
+
+		hist_field = find_event_var(hist_data, system, event, var);
+	}
+
+	if (!hist_field)
+		hist_err_event("onmatch: Couldn't find onmatch param: $", system, event, var);
+
+	return hist_field;
+}
+
+static struct hist_field *
+onmatch_create_field_var(struct hist_trigger_data *hist_data,
+			 struct action_data *data, char *system,
+			 char *event, char *var)
+{
+	struct hist_field *hist_field = NULL;
+	struct field_var *field_var;
+
+	/*
+	 * First try to create a field var on the target event (the
+	 * currently being defined).  This will create a variable for
+	 * unqualified fields on the target event, or if qualified,
+	 * target fields that have qualified names matching the target.
+	 */
+	field_var = create_target_field_var(hist_data, system, event, var);
+
+	if (field_var && !IS_ERR(field_var)) {
+		save_field_var(hist_data, field_var);
+		hist_field = field_var->var;
+	} else {
+		field_var = NULL;
+		/*
+		 * If no explicit system.event is specfied, default to
+		 * looking for fields on the onmatch(system.event.xxx)
+		 * event.
+		 */
+		if (!system) {
+			system = data->onmatch.match_event_system;
+			event = data->onmatch.match_event;
+		}
+
+		/*
+		 * At this point, we're looking at a field on another
+		 * event.  Because we can't modify a hist trigger on
+		 * another event to add a variable for a field, we need
+		 * to create a new trigger on that event and create the
+		 * variable at the same time.
+		 */
+		hist_field = create_field_var_hist(hist_data, system, event, var);
+		if (IS_ERR(hist_field))
+			goto free;
+	}
+ out:
+	return hist_field;
+ free:
+	destroy_field_var(field_var);
+	hist_field = NULL;
+	goto out;
+}
+
+static int onmatch_create(struct hist_trigger_data *hist_data,
+			  struct trace_event_file *file,
+			  struct action_data *data)
+{
+	char *event_name, *param, *system = NULL;
+	struct hist_field *hist_field, *var_ref;
+	unsigned int i, var_ref_idx;
+	unsigned int field_pos = 0;
+	struct synth_event *event;
+	int ret = 0;
+
+	mutex_lock(&synth_event_mutex);
+	event = find_synth_event(data->onmatch.synth_event_name);
+	if (!event) {
+		hist_err("onmatch: Couldn't find synthetic event: ", data->onmatch.synth_event_name);
+		mutex_unlock(&synth_event_mutex);
+		return -EINVAL;
+	}
+	event->ref++;
+	mutex_unlock(&synth_event_mutex);
+
+	var_ref_idx = hist_data->n_var_refs;
+
+	for (i = 0; i < data->n_params; i++) {
+		char *p;
+
+		p = param = kstrdup(data->params[i], GFP_KERNEL);
+		if (!param) {
+			ret = -ENOMEM;
+			goto err;
+		}
+
+		system = strsep(&param, ".");
+		if (!param) {
+			param = (char *)system;
+			system = event_name = NULL;
+		} else {
+			event_name = strsep(&param, ".");
+			if (!param) {
+				kfree(p);
+				ret = -EINVAL;
+				goto err;
+			}
+		}
+
+		if (param[0] == '$')
+			hist_field = onmatch_find_var(hist_data, data, system,
+						      event_name, param);
+		else
+			hist_field = onmatch_create_field_var(hist_data, data,
+							      system,
+							      event_name,
+							      param);
+
+		if (!hist_field) {
+			kfree(p);
+			ret = -EINVAL;
+			goto err;
+		}
+
+		if (check_synth_field(event, hist_field, field_pos) == 0) {
+			var_ref = create_var_ref(hist_field, system, event_name);
+			if (!var_ref) {
+				kfree(p);
+				ret = -ENOMEM;
+				goto err;
+			}
+
+			save_synth_var_ref(hist_data, var_ref);
+			field_pos++;
+			kfree(p);
+			continue;
+		}
+
+		hist_err_event("onmatch: Param type doesn't match synthetic event field type: ",
+			       system, event_name, param);
+		kfree(p);
+		ret = -EINVAL;
+		goto err;
+	}
+
+	if (field_pos != event->n_fields) {
+		hist_err("onmatch: Param count doesn't match synthetic event field count: ", event->name);
+		ret = -EINVAL;
+		goto err;
+	}
+
+	data->fn = action_trace;
+	data->onmatch.synth_event = event;
+	data->onmatch.var_ref_idx = var_ref_idx;
+ out:
+	return ret;
+ err:
+	mutex_lock(&synth_event_mutex);
+	event->ref--;
+	mutex_unlock(&synth_event_mutex);
+
+	goto out;
+}
+
+static struct action_data *onmatch_parse(struct trace_array *tr, char *str)
+{
+	char *match_event, *match_event_system;
+	char *synth_event_name, *params;
+	struct action_data *data;
+	int ret = -EINVAL;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return ERR_PTR(-ENOMEM);
+
+	match_event = strsep(&str, ")");
+	if (!match_event || !str) {
+		hist_err("onmatch: Missing closing paren: ", match_event);
+		goto free;
+	}
+
+	match_event_system = strsep(&match_event, ".");
+	if (!match_event) {
+		hist_err("onmatch: Missing subsystem for match event: ", match_event_system);
+		goto free;
+	}
+
+	if (IS_ERR(event_file(tr, match_event_system, match_event))) {
+		hist_err_event("onmatch: Invalid subsystem or event name: ",
+			       match_event_system, match_event, NULL);
+		goto free;
+	}
+
+	data->onmatch.match_event = kstrdup(match_event, GFP_KERNEL);
+	if (!data->onmatch.match_event) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	data->onmatch.match_event_system = kstrdup(match_event_system, GFP_KERNEL);
+	if (!data->onmatch.match_event_system) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	strsep(&str, ".");
+	if (!str) {
+		hist_err("onmatch: Missing . after onmatch(): ", str);
+		goto free;
+	}
+
+	synth_event_name = strsep(&str, "(");
+	if (!synth_event_name || !str) {
+		hist_err("onmatch: Missing opening paramlist paren: ", synth_event_name);
+		goto free;
 	}
 
-	hist_data->fields[val_idx] = create_hist_field(field, flags);
-	if (!hist_data->fields[val_idx]) {
+	data->onmatch.synth_event_name = kstrdup(synth_event_name, GFP_KERNEL);
+	if (!data->onmatch.synth_event_name) {
 		ret = -ENOMEM;
+		goto free;
+	}
+
+	params = strsep(&str, ")");
+	if (!params || !str || (str && strlen(str))) {
+		hist_err("onmatch: Missing closing paramlist paren: ", params);
+		goto free;
+	}
+
+	ret = parse_action_params(params, data);
+	if (ret)
+		goto free;
+ out:
+	return data;
+ free:
+	onmatch_destroy(data);
+	data = ERR_PTR(ret);
+	goto out;
+}
+
+static int create_hitcount_val(struct hist_trigger_data *hist_data)
+{
+	hist_data->fields[HITCOUNT_IDX] =
+		create_hist_field(hist_data, NULL, HIST_FIELD_FL_HITCOUNT, NULL);
+	if (!hist_data->fields[HITCOUNT_IDX])
+		return -ENOMEM;
+
+	hist_data->n_vals++;
+	hist_data->n_fields++;
+
+	if (WARN_ON(hist_data->n_vals > TRACING_MAP_VALS_MAX))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int __create_val_field(struct hist_trigger_data *hist_data,
+			      unsigned int val_idx,
+			      struct trace_event_file *file,
+			      char *var_name, char *field_str,
+			      unsigned long flags)
+{
+	struct hist_field *hist_field;
+	int ret = 0;
+
+	hist_field = parse_expr(hist_data, file, field_str, flags, var_name, 0);
+	if (IS_ERR(hist_field)) {
+		ret = PTR_ERR(hist_field);
 		goto out;
 	}
 
+	hist_data->fields[val_idx] = hist_field;
+
 	++hist_data->n_vals;
+	++hist_data->n_fields;
 
-	if (WARN_ON(hist_data->n_vals > TRACING_MAP_VALS_MAX))
+	if (WARN_ON(hist_data->n_vals > TRACING_MAP_VALS_MAX + TRACING_MAP_VARS_MAX))
 		ret = -EINVAL;
  out:
 	return ret;
 }
 
+static int create_val_field(struct hist_trigger_data *hist_data,
+			    unsigned int val_idx,
+			    struct trace_event_file *file,
+			    char *field_str)
+{
+	if (WARN_ON(val_idx >= TRACING_MAP_VALS_MAX))
+		return -EINVAL;
+
+	return __create_val_field(hist_data, val_idx, file, NULL, field_str, 0);
+}
+
+static int create_var_field(struct hist_trigger_data *hist_data,
+			    unsigned int val_idx,
+			    struct trace_event_file *file,
+			    char *var_name, char *expr_str)
+{
+	unsigned long flags = 0;
+
+	if (WARN_ON(val_idx >= TRACING_MAP_VALS_MAX + TRACING_MAP_VARS_MAX))
+		return -EINVAL;
+
+	if (find_var(hist_data, file, var_name) && !hist_data->remove) {
+		hist_err("Variable already defined: ", var_name);
+		return -EINVAL;
+	}
+
+	flags |= HIST_FIELD_FL_VAR;
+	hist_data->n_vars++;
+	if (WARN_ON(hist_data->n_vars > TRACING_MAP_VARS_MAX))
+		return -EINVAL;
+
+	return __create_val_field(hist_data, val_idx, file, var_name, expr_str, flags);
+}
+
 static int create_val_fields(struct hist_trigger_data *hist_data,
 			     struct trace_event_file *file)
 {
 	char *fields_str, *field_str;
-	unsigned int i, j;
+	unsigned int i, j = 1;
 	int ret;
 
 	ret = create_hitcount_val(hist_data);
@@ -533,12 +3910,15 @@ static int create_val_fields(struct hist_trigger_data *hist_data,
 		field_str = strsep(&fields_str, ",");
 		if (!field_str)
 			break;
+
 		if (strcmp(field_str, "hitcount") == 0)
 			continue;
+
 		ret = create_val_field(hist_data, j++, file, field_str);
 		if (ret)
 			goto out;
 	}
+
 	if (fields_str && (strcmp(fields_str, "hitcount") != 0))
 		ret = -EINVAL;
  out:
@@ -551,12 +3931,13 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 			    struct trace_event_file *file,
 			    char *field_str)
 {
-	struct ftrace_event_field *field = NULL;
+	struct hist_field *hist_field = NULL;
+
 	unsigned long flags = 0;
 	unsigned int key_size;
 	int ret = 0;
 
-	if (WARN_ON(key_idx >= TRACING_MAP_FIELDS_MAX))
+	if (WARN_ON(key_idx >= HIST_FIELDS_MAX))
 		return -EINVAL;
 
 	flags |= HIST_FIELD_FL_KEY;
@@ -564,57 +3945,40 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 	if (strcmp(field_str, "stacktrace") == 0) {
 		flags |= HIST_FIELD_FL_STACKTRACE;
 		key_size = sizeof(unsigned long) * HIST_STACKTRACE_DEPTH;
+		hist_field = create_hist_field(hist_data, NULL, flags, NULL);
 	} else {
-		char *field_name = strsep(&field_str, ".");
-
-		if (field_str) {
-			if (strcmp(field_str, "hex") == 0)
-				flags |= HIST_FIELD_FL_HEX;
-			else if (strcmp(field_str, "sym") == 0)
-				flags |= HIST_FIELD_FL_SYM;
-			else if (strcmp(field_str, "sym-offset") == 0)
-				flags |= HIST_FIELD_FL_SYM_OFFSET;
-			else if ((strcmp(field_str, "execname") == 0) &&
-				 (strcmp(field_name, "common_pid") == 0))
-				flags |= HIST_FIELD_FL_EXECNAME;
-			else if (strcmp(field_str, "syscall") == 0)
-				flags |= HIST_FIELD_FL_SYSCALL;
-			else if (strcmp(field_str, "log2") == 0)
-				flags |= HIST_FIELD_FL_LOG2;
-			else {
-				ret = -EINVAL;
-				goto out;
-			}
+		hist_field = parse_expr(hist_data, file, field_str, flags,
+					NULL, 0);
+		if (IS_ERR(hist_field)) {
+			ret = PTR_ERR(hist_field);
+			goto out;
 		}
 
-		field = trace_find_event_field(file->event_call, field_name);
-		if (!field || !field->size) {
+		if (hist_field->flags & HIST_FIELD_FL_VAR_REF) {
+			hist_err("Using variable references as keys not supported: ", field_str);
+			destroy_hist_field(hist_field, 0);
 			ret = -EINVAL;
 			goto out;
 		}
 
-		if (is_string_field(field))
-			key_size = MAX_FILTER_STR_VAL;
-		else
-			key_size = field->size;
+		key_size = hist_field->size;
 	}
 
-	hist_data->fields[key_idx] = create_hist_field(field, flags);
-	if (!hist_data->fields[key_idx]) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	hist_data->fields[key_idx] = hist_field;
 
 	key_size = ALIGN(key_size, sizeof(u64));
 	hist_data->fields[key_idx]->size = key_size;
 	hist_data->fields[key_idx]->offset = key_offset;
+
 	hist_data->key_size += key_size;
+
 	if (hist_data->key_size > HIST_KEY_SIZE_MAX) {
 		ret = -EINVAL;
 		goto out;
 	}
 
 	hist_data->n_keys++;
+	hist_data->n_fields++;
 
 	if (WARN_ON(hist_data->n_keys > TRACING_MAP_KEYS_MAX))
 		return -EINVAL;
@@ -658,21 +4022,113 @@ static int create_key_fields(struct hist_trigger_data *hist_data,
 	return ret;
 }
 
+static int create_var_fields(struct hist_trigger_data *hist_data,
+			     struct trace_event_file *file)
+{
+	unsigned int i, j = hist_data->n_vals;
+	int ret = 0;
+
+	unsigned int n_vars = hist_data->attrs->var_defs.n_vars;
+
+	for (i = 0; i < n_vars; i++) {
+		char *var_name = hist_data->attrs->var_defs.name[i];
+		char *expr = hist_data->attrs->var_defs.expr[i];
+
+		ret = create_var_field(hist_data, j++, file, var_name, expr);
+		if (ret)
+			goto out;
+	}
+ out:
+	return ret;
+}
+
+static void free_var_defs(struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->attrs->var_defs.n_vars; i++) {
+		kfree(hist_data->attrs->var_defs.name[i]);
+		kfree(hist_data->attrs->var_defs.expr[i]);
+	}
+
+	hist_data->attrs->var_defs.n_vars = 0;
+}
+
+static int parse_var_defs(struct hist_trigger_data *hist_data)
+{
+	char *s, *str, *var_name, *field_str;
+	unsigned int i, j, n_vars = 0;
+	int ret = 0;
+
+	for (i = 0; i < hist_data->attrs->n_assignments; i++) {
+		str = hist_data->attrs->assignment_str[i];
+		for (j = 0; j < TRACING_MAP_VARS_MAX; j++) {
+			field_str = strsep(&str, ",");
+			if (!field_str)
+				break;
+
+			var_name = strsep(&field_str, "=");
+			if (!var_name || !field_str) {
+				hist_err("Malformed assignment: ", var_name);
+				ret = -EINVAL;
+				goto free;
+			}
+
+			if (n_vars == TRACING_MAP_VARS_MAX) {
+				hist_err("Too many variables defined: ", var_name);
+				ret = -EINVAL;
+				goto free;
+			}
+
+			s = kstrdup(var_name, GFP_KERNEL);
+			if (!s) {
+				ret = -ENOMEM;
+				goto free;
+			}
+			hist_data->attrs->var_defs.name[n_vars] = s;
+
+			s = kstrdup(field_str, GFP_KERNEL);
+			if (!s) {
+				kfree(hist_data->attrs->var_defs.name[n_vars]);
+				ret = -ENOMEM;
+				goto free;
+			}
+			hist_data->attrs->var_defs.expr[n_vars++] = s;
+
+			hist_data->attrs->var_defs.n_vars = n_vars;
+		}
+	}
+
+	return ret;
+ free:
+	free_var_defs(hist_data);
+
+	return ret;
+}
+
 static int create_hist_fields(struct hist_trigger_data *hist_data,
 			      struct trace_event_file *file)
 {
 	int ret;
 
+	ret = parse_var_defs(hist_data);
+	if (ret)
+		goto out;
+
 	ret = create_val_fields(hist_data, file);
 	if (ret)
 		goto out;
 
-	ret = create_key_fields(hist_data, file);
+	ret = create_var_fields(hist_data, file);
 	if (ret)
 		goto out;
 
-	hist_data->n_fields = hist_data->n_vals + hist_data->n_keys;
+	ret = create_key_fields(hist_data, file);
+	if (ret)
+		goto out;
  out:
+	free_var_defs(hist_data);
+
 	return ret;
 }
 
@@ -695,7 +4151,7 @@ static int create_sort_keys(struct hist_trigger_data *hist_data)
 	char *fields_str = hist_data->attrs->sort_key_str;
 	struct tracing_map_sort_key *sort_key;
 	int descending, ret = 0;
-	unsigned int i, j;
+	unsigned int i, j, k;
 
 	hist_data->n_sort_keys = 1; /* we always have at least one, hitcount */
 
@@ -743,12 +4199,19 @@ static int create_sort_keys(struct hist_trigger_data *hist_data)
 			continue;
 		}
 
-		for (j = 1; j < hist_data->n_fields; j++) {
+		for (j = 1, k = 1; j < hist_data->n_fields; j++) {
+			unsigned int idx;
+
 			hist_field = hist_data->fields[j];
+			if (hist_field->flags & HIST_FIELD_FL_VAR)
+				continue;
+
+			idx = k++;
+
 			test_name = hist_field_name(hist_field, 0);
 
 			if (strcmp(field_name, test_name) == 0) {
-				sort_key->field_idx = j;
+				sort_key->field_idx = idx;
 				descending = is_descending(field_str);
 				if (descending < 0) {
 					ret = descending;
@@ -763,16 +4226,230 @@ static int create_sort_keys(struct hist_trigger_data *hist_data)
 			break;
 		}
 	}
+
 	hist_data->n_sort_keys = i;
  out:
 	return ret;
 }
 
+static void destroy_actions(struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		struct action_data *data = hist_data->actions[i];
+
+		if (data->fn == action_trace)
+			onmatch_destroy(data);
+		else if (data->fn == onmax_save)
+			onmax_destroy(data);
+		else
+			kfree(data);
+	}
+}
+
+static int parse_actions(struct hist_trigger_data *hist_data)
+{
+	struct trace_array *tr = hist_data->event_file->tr;
+	struct action_data *data;
+	unsigned int i;
+	int ret = 0;
+	char *str;
+
+	for (i = 0; i < hist_data->attrs->n_actions; i++) {
+		str = hist_data->attrs->action_str[i];
+
+		if (strncmp(str, "onmatch(", strlen("onmatch(")) == 0) {
+			char *action_str = str + strlen("onmatch(");
+
+			data = onmatch_parse(tr, action_str);
+			if (IS_ERR(data)) {
+				ret = PTR_ERR(data);
+				break;
+			}
+			data->fn = action_trace;
+		} else if (strncmp(str, "onmax(", strlen("onmax(")) == 0) {
+			char *action_str = str + strlen("onmax(");
+
+			data = onmax_parse(action_str);
+			if (IS_ERR(data)) {
+				ret = PTR_ERR(data);
+				break;
+			}
+			data->fn = onmax_save;
+		} else {
+			ret = -EINVAL;
+			break;
+		}
+
+		hist_data->actions[hist_data->n_actions++] = data;
+	}
+
+	return ret;
+}
+
+static int create_actions(struct hist_trigger_data *hist_data,
+			  struct trace_event_file *file)
+{
+	struct action_data *data;
+	unsigned int i;
+	int ret = 0;
+
+	for (i = 0; i < hist_data->attrs->n_actions; i++) {
+		data = hist_data->actions[i];
+
+		if (data->fn == action_trace) {
+			ret = onmatch_create(hist_data, file, data);
+			if (ret)
+				return ret;
+		} else if (data->fn == onmax_save) {
+			ret = onmax_create(hist_data, data);
+			if (ret)
+				return ret;
+		}
+	}
+
+	return ret;
+}
+
+static void print_actions(struct seq_file *m,
+			  struct hist_trigger_data *hist_data,
+			  struct tracing_map_elt *elt)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		struct action_data *data = hist_data->actions[i];
+
+		if (data->fn == onmax_save)
+			onmax_print(m, hist_data, elt, data);
+	}
+}
+
+static void print_onmax_spec(struct seq_file *m,
+			     struct hist_trigger_data *hist_data,
+			     struct action_data *data)
+{
+	unsigned int i;
+
+	seq_puts(m, ":onmax(");
+	seq_printf(m, "%s", data->onmax.var_str);
+	seq_printf(m, ").%s(", data->onmax.fn_name);
+
+	for (i = 0; i < hist_data->n_max_vars; i++) {
+		seq_printf(m, "%s", hist_data->max_vars[i]->var->var.name);
+		if (i < hist_data->n_max_vars - 1)
+			seq_puts(m, ",");
+	}
+	seq_puts(m, ")");
+}
+
+static void print_onmatch_spec(struct seq_file *m,
+			       struct hist_trigger_data *hist_data,
+			       struct action_data *data)
+{
+	unsigned int i;
+
+	seq_printf(m, ":onmatch(%s.%s).", data->onmatch.match_event_system,
+		   data->onmatch.match_event);
+
+	seq_printf(m, "%s(", data->onmatch.synth_event->name);
+
+	for (i = 0; i < data->n_params; i++) {
+		if (i)
+			seq_puts(m, ",");
+		seq_printf(m, "%s", data->params[i]);
+	}
+
+	seq_puts(m, ")");
+}
+
+static bool actions_match(struct hist_trigger_data *hist_data,
+			  struct hist_trigger_data *hist_data_test)
+{
+	unsigned int i, j;
+
+	if (hist_data->n_actions != hist_data_test->n_actions)
+		return false;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		struct action_data *data = hist_data->actions[i];
+		struct action_data *data_test = hist_data_test->actions[i];
+
+		if (data->fn != data_test->fn)
+			return false;
+
+		if (data->n_params != data_test->n_params)
+			return false;
+
+		for (j = 0; j < data->n_params; j++) {
+			if (strcmp(data->params[j], data_test->params[j]) != 0)
+				return false;
+		}
+
+		if (data->fn == action_trace) {
+			if (strcmp(data->onmatch.synth_event_name,
+				   data_test->onmatch.synth_event_name) != 0)
+				return false;
+			if (strcmp(data->onmatch.match_event_system,
+				   data_test->onmatch.match_event_system) != 0)
+				return false;
+			if (strcmp(data->onmatch.match_event,
+				   data_test->onmatch.match_event) != 0)
+				return false;
+		} else if (data->fn == onmax_save) {
+			if (strcmp(data->onmax.var_str,
+				   data_test->onmax.var_str) != 0)
+				return false;
+			if (strcmp(data->onmax.fn_name,
+				   data_test->onmax.fn_name) != 0)
+				return false;
+		}
+	}
+
+	return true;
+}
+
+
+static void print_actions_spec(struct seq_file *m,
+			       struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		struct action_data *data = hist_data->actions[i];
+
+		if (data->fn == action_trace)
+			print_onmatch_spec(m, hist_data, data);
+		else if (data->fn == onmax_save)
+			print_onmax_spec(m, hist_data, data);
+	}
+}
+
+static void destroy_field_var_hists(struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_field_var_hists; i++) {
+		kfree(hist_data->field_var_hists[i]->cmd);
+		kfree(hist_data->field_var_hists[i]);
+	}
+}
+
 static void destroy_hist_data(struct hist_trigger_data *hist_data)
 {
+	if (!hist_data)
+		return;
+
 	destroy_hist_trigger_attrs(hist_data->attrs);
 	destroy_hist_fields(hist_data);
 	tracing_map_destroy(hist_data->map);
+
+	destroy_actions(hist_data);
+	destroy_field_vars(hist_data);
+	destroy_field_var_hists(hist_data);
+	destroy_synth_var_refs(hist_data);
+
 	kfree(hist_data);
 }
 
@@ -781,7 +4458,7 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
 	struct tracing_map *map = hist_data->map;
 	struct ftrace_event_field *field;
 	struct hist_field *hist_field;
-	int i, idx;
+	int i, idx = 0;
 
 	for_each_hist_field(i, hist_data) {
 		hist_field = hist_data->fields[i];
@@ -792,6 +4469,9 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
 
 			if (hist_field->flags & HIST_FIELD_FL_STACKTRACE)
 				cmp_fn = tracing_map_cmp_none;
+			else if (!field)
+				cmp_fn = tracing_map_cmp_num(hist_field->size,
+							     hist_field->is_signed);
 			else if (is_string_field(field))
 				cmp_fn = tracing_map_cmp_string;
 			else
@@ -800,36 +4480,29 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
 			idx = tracing_map_add_key_field(map,
 							hist_field->offset,
 							cmp_fn);
-
-		} else
+		} else if (!(hist_field->flags & HIST_FIELD_FL_VAR))
 			idx = tracing_map_add_sum_field(map);
 
 		if (idx < 0)
 			return idx;
-	}
-
-	return 0;
-}
-
-static bool need_tracing_map_ops(struct hist_trigger_data *hist_data)
-{
-	struct hist_field *key_field;
-	unsigned int i;
-
-	for_each_hist_key_field(i, hist_data) {
-		key_field = hist_data->fields[i];
 
-		if (key_field->flags & HIST_FIELD_FL_EXECNAME)
-			return true;
+		if (hist_field->flags & HIST_FIELD_FL_VAR) {
+			idx = tracing_map_add_var(map);
+			if (idx < 0)
+				return idx;
+			hist_field->var.idx = idx;
+			hist_field->var.hist_data = hist_data;
+		}
 	}
 
-	return false;
+	return 0;
 }
 
 static struct hist_trigger_data *
 create_hist_data(unsigned int map_bits,
 		 struct hist_trigger_attrs *attrs,
-		 struct trace_event_file *file)
+		 struct trace_event_file *file,
+		 bool remove)
 {
 	const struct tracing_map_ops *map_ops = NULL;
 	struct hist_trigger_data *hist_data;
@@ -840,6 +4513,12 @@ create_hist_data(unsigned int map_bits,
 		return ERR_PTR(-ENOMEM);
 
 	hist_data->attrs = attrs;
+	hist_data->remove = remove;
+	hist_data->event_file = file;
+
+	ret = parse_actions(hist_data);
+	if (ret)
+		goto free;
 
 	ret = create_hist_fields(hist_data, file);
 	if (ret)
@@ -849,8 +4528,7 @@ create_hist_data(unsigned int map_bits,
 	if (ret)
 		goto free;
 
-	if (need_tracing_map_ops(hist_data))
-		map_ops = &hist_trigger_elt_comm_ops;
+	map_ops = &hist_trigger_elt_data_ops;
 
 	hist_data->map = tracing_map_create(map_bits, hist_data->key_size,
 					    map_ops, hist_data);
@@ -863,12 +4541,6 @@ create_hist_data(unsigned int map_bits,
 	ret = create_tracing_map_fields(hist_data);
 	if (ret)
 		goto free;
-
-	ret = tracing_map_init(hist_data->map);
-	if (ret)
-		goto free;
-
-	hist_data->event_file = file;
  out:
 	return hist_data;
  free:
@@ -882,18 +4554,39 @@ create_hist_data(unsigned int map_bits,
 }
 
 static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
-				    struct tracing_map_elt *elt,
-				    void *rec)
+				    struct tracing_map_elt *elt, void *rec,
+				    struct ring_buffer_event *rbe,
+				    u64 *var_ref_vals)
 {
+	struct hist_elt_data *elt_data;
 	struct hist_field *hist_field;
-	unsigned int i;
+	unsigned int i, var_idx;
 	u64 hist_val;
 
+	elt_data = elt->private_data;
+	elt_data->var_ref_vals = var_ref_vals;
+
 	for_each_hist_val_field(i, hist_data) {
 		hist_field = hist_data->fields[i];
-		hist_val = hist_field->fn(hist_field, rec);
+		hist_val = hist_field->fn(hist_field, elt, rbe, rec);
+		if (hist_field->flags & HIST_FIELD_FL_VAR) {
+			var_idx = hist_field->var.idx;
+			tracing_map_set_var(elt, var_idx, hist_val);
+			continue;
+		}
 		tracing_map_update_sum(elt, i, hist_val);
 	}
+
+	for_each_hist_key_field(i, hist_data) {
+		hist_field = hist_data->fields[i];
+		if (hist_field->flags & HIST_FIELD_FL_VAR) {
+			hist_val = hist_field->fn(hist_field, elt, rbe, rec);
+			var_idx = hist_field->var.idx;
+			tracing_map_set_var(elt, var_idx, hist_val);
+		}
+	}
+
+	update_field_vars(hist_data, elt, rbe, rec);
 }
 
 static inline void add_to_key(char *compound_key, void *key,
@@ -920,15 +4613,31 @@ static inline void add_to_key(char *compound_key, void *key,
 	memcpy(compound_key + key_field->offset, key, size);
 }
 
-static void event_hist_trigger(struct event_trigger_data *data, void *rec)
+static void
+hist_trigger_actions(struct hist_trigger_data *hist_data,
+		     struct tracing_map_elt *elt, void *rec,
+		     struct ring_buffer_event *rbe, u64 *var_ref_vals)
+{
+	struct action_data *data;
+	unsigned int i;
+
+	for (i = 0; i < hist_data->n_actions; i++) {
+		data = hist_data->actions[i];
+		data->fn(hist_data, elt, rec, rbe, data, var_ref_vals);
+	}
+}
+
+static void event_hist_trigger(struct event_trigger_data *data, void *rec,
+			       struct ring_buffer_event *rbe)
 {
 	struct hist_trigger_data *hist_data = data->private_data;
 	bool use_compound_key = (hist_data->n_keys > 1);
 	unsigned long entries[HIST_STACKTRACE_DEPTH];
+	u64 var_ref_vals[TRACING_MAP_VARS_MAX];
 	char compound_key[HIST_KEY_SIZE_MAX];
+	struct tracing_map_elt *elt = NULL;
 	struct stack_trace stacktrace;
 	struct hist_field *key_field;
-	struct tracing_map_elt *elt;
 	u64 field_contents;
 	void *key = NULL;
 	unsigned int i;
@@ -949,7 +4658,7 @@ static void event_hist_trigger(struct event_trigger_data *data, void *rec)
 
 			key = entries;
 		} else {
-			field_contents = key_field->fn(key_field, rec);
+			field_contents = key_field->fn(key_field, elt, rbe, rec);
 			if (key_field->flags & HIST_FIELD_FL_STRING) {
 				key = (void *)(unsigned long)field_contents;
 				use_compound_key = true;
@@ -964,9 +4673,18 @@ static void event_hist_trigger(struct event_trigger_data *data, void *rec)
 	if (use_compound_key)
 		key = compound_key;
 
+	if (hist_data->n_var_refs &&
+	    !resolve_var_refs(hist_data, key, var_ref_vals, false))
+		return;
+
 	elt = tracing_map_insert(hist_data->map, key);
-	if (elt)
-		hist_trigger_elt_update(hist_data, elt, rec);
+	if (!elt)
+		return;
+
+	hist_trigger_elt_update(hist_data, elt, rec, rbe, var_ref_vals);
+
+	if (resolve_var_refs(hist_data, key, var_ref_vals, true))
+		hist_trigger_actions(hist_data, elt, rec, rbe, var_ref_vals);
 }
 
 static void hist_trigger_stacktrace_print(struct seq_file *m,
@@ -1023,7 +4741,13 @@ hist_trigger_entry_print(struct seq_file *m,
 			seq_printf(m, "%s: [%llx] %-55s", field_name,
 				   uval, str);
 		} else if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
-			char *comm = elt->private_data;
+			struct hist_elt_data *elt_data = elt->private_data;
+			char *comm;
+
+			if (WARN_ON_ONCE(!elt_data))
+				return;
+
+			comm = elt_data->comm;
 
 			uval = *(u64 *)(key + key_field->offset);
 			seq_printf(m, "%s: %-16s[%10llu]", field_name,
@@ -1067,6 +4791,10 @@ hist_trigger_entry_print(struct seq_file *m,
 	for (i = 1; i < hist_data->n_vals; i++) {
 		field_name = hist_field_name(hist_data->fields[i], 0);
 
+		if (hist_data->fields[i]->flags & HIST_FIELD_FL_VAR ||
+		    hist_data->fields[i]->flags & HIST_FIELD_FL_EXPR)
+			continue;
+
 		if (hist_data->fields[i]->flags & HIST_FIELD_FL_HEX) {
 			seq_printf(m, "  %s: %10llx", field_name,
 				   tracing_map_read_sum(elt, i));
@@ -1076,6 +4804,8 @@ hist_trigger_entry_print(struct seq_file *m,
 		}
 	}
 
+	print_actions(m, hist_data, elt);
+
 	seq_puts(m, "\n");
 }
 
@@ -1144,6 +4874,11 @@ static int hist_show(struct seq_file *m, void *v)
 			hist_trigger_show(m, data, n++);
 	}
 
+	if (have_hist_err()) {
+		seq_printf(m, "\nERROR: %s\n", hist_err_str);
+		seq_printf(m, "  Last command: %s\n", last_hist_cmd);
+	}
+
  out_unlock:
 	mutex_unlock(&event_mutex);
 
@@ -1162,37 +4897,22 @@ const struct file_operations event_hist_fops = {
 	.release = single_release,
 };
 
-static const char *get_hist_field_flags(struct hist_field *hist_field)
-{
-	const char *flags_str = NULL;
-
-	if (hist_field->flags & HIST_FIELD_FL_HEX)
-		flags_str = "hex";
-	else if (hist_field->flags & HIST_FIELD_FL_SYM)
-		flags_str = "sym";
-	else if (hist_field->flags & HIST_FIELD_FL_SYM_OFFSET)
-		flags_str = "sym-offset";
-	else if (hist_field->flags & HIST_FIELD_FL_EXECNAME)
-		flags_str = "execname";
-	else if (hist_field->flags & HIST_FIELD_FL_SYSCALL)
-		flags_str = "syscall";
-	else if (hist_field->flags & HIST_FIELD_FL_LOG2)
-		flags_str = "log2";
-
-	return flags_str;
-}
-
 static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
 {
 	const char *field_name = hist_field_name(hist_field, 0);
 
-	seq_printf(m, "%s", field_name);
-	if (hist_field->flags) {
-		const char *flags_str = get_hist_field_flags(hist_field);
-
-		if (flags_str)
-			seq_printf(m, ".%s", flags_str);
-	}
+	if (hist_field->var.name)
+		seq_printf(m, "%s=", hist_field->var.name);
+
+	if (hist_field->flags & HIST_FIELD_FL_CPU)
+		seq_puts(m, "cpu");
+	else if (field_name) {
+		if (hist_field->flags & HIST_FIELD_FL_VAR_REF ||
+		    hist_field->flags & HIST_FIELD_FL_ALIAS)
+			seq_putc(m, '$');
+		seq_printf(m, "%s", field_name);
+	} else if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP)
+		seq_puts(m, "common_timestamp");
 }
 
 static int event_hist_trigger_print(struct seq_file *m,
@@ -1200,7 +4920,8 @@ static int event_hist_trigger_print(struct seq_file *m,
 				    struct event_trigger_data *data)
 {
 	struct hist_trigger_data *hist_data = data->private_data;
-	struct hist_field *key_field;
+	struct hist_field *field;
+	bool have_var = false;
 	unsigned int i;
 
 	seq_puts(m, "hist:");
@@ -1211,25 +4932,47 @@ static int event_hist_trigger_print(struct seq_file *m,
 	seq_puts(m, "keys=");
 
 	for_each_hist_key_field(i, hist_data) {
-		key_field = hist_data->fields[i];
+		field = hist_data->fields[i];
 
 		if (i > hist_data->n_vals)
 			seq_puts(m, ",");
 
-		if (key_field->flags & HIST_FIELD_FL_STACKTRACE)
+		if (field->flags & HIST_FIELD_FL_STACKTRACE)
 			seq_puts(m, "stacktrace");
 		else
-			hist_field_print(m, key_field);
+			hist_field_print(m, field);
 	}
 
 	seq_puts(m, ":vals=");
 
 	for_each_hist_val_field(i, hist_data) {
+		field = hist_data->fields[i];
+		if (field->flags & HIST_FIELD_FL_VAR) {
+			have_var = true;
+			continue;
+		}
+
 		if (i == HITCOUNT_IDX)
 			seq_puts(m, "hitcount");
 		else {
 			seq_puts(m, ",");
-			hist_field_print(m, hist_data->fields[i]);
+			hist_field_print(m, field);
+		}
+	}
+
+	if (have_var) {
+		unsigned int n = 0;
+
+		seq_puts(m, ":");
+
+		for_each_hist_val_field(i, hist_data) {
+			field = hist_data->fields[i];
+
+			if (field->flags & HIST_FIELD_FL_VAR) {
+				if (n++)
+					seq_puts(m, ",");
+				hist_field_print(m, field);
+			}
 		}
 	}
 
@@ -1237,28 +4980,36 @@ static int event_hist_trigger_print(struct seq_file *m,
 
 	for (i = 0; i < hist_data->n_sort_keys; i++) {
 		struct tracing_map_sort_key *sort_key;
+		unsigned int idx, first_key_idx;
+
+		/* skip VAR vals */
+		first_key_idx = hist_data->n_vals - hist_data->n_vars;
 
 		sort_key = &hist_data->sort_keys[i];
+		idx = sort_key->field_idx;
+
+		if (WARN_ON(idx >= HIST_FIELDS_MAX))
+			return -EINVAL;
 
 		if (i > 0)
 			seq_puts(m, ",");
 
-		if (sort_key->field_idx == HITCOUNT_IDX)
+		if (idx == HITCOUNT_IDX)
 			seq_puts(m, "hitcount");
 		else {
-			unsigned int idx = sort_key->field_idx;
-
-			if (WARN_ON(idx >= TRACING_MAP_FIELDS_MAX))
-				return -EINVAL;
-
+			if (idx >= first_key_idx)
+				idx += hist_data->n_vars;
 			hist_field_print(m, hist_data->fields[idx]);
 		}
 
 		if (sort_key->descending)
 			seq_puts(m, ".descending");
 	}
-
 	seq_printf(m, ":size=%u", (1 << hist_data->map->map_bits));
+	if (hist_data->enable_timestamps)
+		seq_printf(m, ":clock=%s", hist_data->attrs->clock);
+
+	print_actions_spec(m, hist_data);
 
 	if (data->filter_str)
 		seq_printf(m, " if %s", data->filter_str);
@@ -1286,6 +5037,21 @@ static int event_hist_trigger_init(struct event_trigger_ops *ops,
 	return 0;
 }
 
+static void unregister_field_var_hists(struct hist_trigger_data *hist_data)
+{
+	struct trace_event_file *file;
+	unsigned int i;
+	char *cmd;
+	int ret;
+
+	for (i = 0; i < hist_data->n_field_var_hists; i++) {
+		file = hist_data->field_var_hists[i]->hist_data->event_file;
+		cmd = hist_data->field_var_hists[i]->cmd;
+		ret = event_hist_trigger_func(&trigger_hist_cmd, file,
+					      "!hist", "hist", cmd);
+	}
+}
+
 static void event_hist_trigger_free(struct event_trigger_ops *ops,
 				    struct event_trigger_data *data)
 {
@@ -1298,7 +5064,13 @@ static void event_hist_trigger_free(struct event_trigger_ops *ops,
 	if (!data->ref) {
 		if (data->name)
 			del_named_trigger(data);
+
 		trigger_data_free(data);
+
+		remove_hist_vars(hist_data);
+
+		unregister_field_var_hists(hist_data);
+
 		destroy_hist_data(hist_data);
 	}
 }
@@ -1425,6 +5197,15 @@ static bool hist_trigger_match(struct event_trigger_data *data,
 			return false;
 		if (key_field->offset != key_field_test->offset)
 			return false;
+		if (key_field->size != key_field_test->size)
+			return false;
+		if (key_field->is_signed != key_field_test->is_signed)
+			return false;
+		if (!!key_field->var.name != !!key_field_test->var.name)
+			return false;
+		if (key_field->var.name &&
+		    strcmp(key_field->var.name, key_field_test->var.name) != 0)
+			return false;
 	}
 
 	for (i = 0; i < hist_data->n_sort_keys; i++) {
@@ -1440,6 +5221,9 @@ static bool hist_trigger_match(struct event_trigger_data *data,
 	    (strcmp(data->filter_str, data_test->filter_str) != 0))
 		return false;
 
+	if (!actions_match(hist_data, hist_data_test))
+		return false;
+
 	return true;
 }
 
@@ -1456,6 +5240,7 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 		if (named_data) {
 			if (!hist_trigger_match(data, named_data, named_data,
 						true)) {
+				hist_err("Named hist trigger doesn't match existing named trigger (includes variables): ", hist_data->attrs->name);
 				ret = -EINVAL;
 				goto out;
 			}
@@ -1475,13 +5260,16 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 				test->paused = false;
 			else if (hist_data->attrs->clear)
 				hist_clear(test);
-			else
+			else {
+				hist_err("Hist trigger already exists", NULL);
 				ret = -EEXIST;
+			}
 			goto out;
 		}
 	}
  new:
 	if (hist_data->attrs->cont || hist_data->attrs->clear) {
+		hist_err("Can't clear or continue a nonexistent hist trigger", NULL);
 		ret = -ENOENT;
 		goto out;
 	}
@@ -1490,7 +5278,6 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 		data->paused = true;
 
 	if (named_data) {
-		destroy_hist_data(data->private_data);
 		data->private_data = named_data->private_data;
 		set_named_trigger_data(data, named_data);
 		data->ops = &event_hist_trigger_named_ops;
@@ -1502,8 +5289,32 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 			goto out;
 	}
 
-	list_add_rcu(&data->list, &file->triggers);
+	if (hist_data->enable_timestamps) {
+		char *clock = hist_data->attrs->clock;
+
+		ret = tracing_set_clock(file->tr, hist_data->attrs->clock);
+		if (ret) {
+			hist_err("Couldn't set trace_clock: ", clock);
+			goto out;
+		}
+
+		tracing_set_time_stamp_abs(file->tr, true);
+	}
+
+	if (named_data)
+		destroy_hist_data(hist_data);
+
 	ret++;
+ out:
+	return ret;
+}
+
+static int hist_trigger_enable(struct event_trigger_data *data,
+			       struct trace_event_file *file)
+{
+	int ret = 0;
+
+	list_add_tail_rcu(&data->list, &file->triggers);
 
 	update_cond_flag(file);
 
@@ -1512,10 +5323,55 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 		update_cond_flag(file);
 		ret--;
 	}
- out:
+
 	return ret;
 }
 
+static bool have_hist_trigger_match(struct event_trigger_data *data,
+				    struct trace_event_file *file)
+{
+	struct hist_trigger_data *hist_data = data->private_data;
+	struct event_trigger_data *test, *named_data = NULL;
+	bool match = false;
+
+	if (hist_data->attrs->name)
+		named_data = find_named_trigger(hist_data->attrs->name);
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			if (hist_trigger_match(data, test, named_data, false)) {
+				match = true;
+				break;
+			}
+		}
+	}
+
+	return match;
+}
+
+static bool hist_trigger_check_refs(struct event_trigger_data *data,
+				    struct trace_event_file *file)
+{
+	struct hist_trigger_data *hist_data = data->private_data;
+	struct event_trigger_data *test, *named_data = NULL;
+
+	if (hist_data->attrs->name)
+		named_data = find_named_trigger(hist_data->attrs->name);
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			if (!hist_trigger_match(data, test, named_data, false))
+				continue;
+			hist_data = test->private_data;
+			if (check_var_refs(hist_data))
+				return true;
+			break;
+		}
+	}
+
+	return false;
+}
+
 static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops,
 				    struct event_trigger_data *data,
 				    struct trace_event_file *file)
@@ -1541,17 +5397,55 @@ static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops,
 
 	if (unregistered && test->ops->free)
 		test->ops->free(test->ops, test);
+
+	if (hist_data->enable_timestamps) {
+		if (!hist_data->remove || unregistered)
+			tracing_set_time_stamp_abs(file->tr, false);
+	}
+}
+
+static bool hist_file_check_refs(struct trace_event_file *file)
+{
+	struct hist_trigger_data *hist_data;
+	struct event_trigger_data *test;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			hist_data = test->private_data;
+			if (check_var_refs(hist_data))
+				return true;
+		}
+	}
+
+	return false;
 }
 
 static void hist_unreg_all(struct trace_event_file *file)
 {
 	struct event_trigger_data *test, *n;
+	struct hist_trigger_data *hist_data;
+	struct synth_event *se;
+	const char *se_name;
+
+	if (hist_file_check_refs(file))
+		return;
 
 	list_for_each_entry_safe(test, n, &file->triggers, list) {
 		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			hist_data = test->private_data;
 			list_del_rcu(&test->list);
 			trace_event_trigger_enable_disable(file, 0);
+
+			mutex_lock(&synth_event_mutex);
+			se_name = trace_event_name(file->event_call);
+			se = find_synth_event(se_name);
+			if (se)
+				se->ref--;
+			mutex_unlock(&synth_event_mutex);
+
 			update_cond_flag(file);
+			if (hist_data->enable_timestamps)
+				tracing_set_time_stamp_abs(file->tr, false);
 			if (test->ops->free)
 				test->ops->free(test->ops, test);
 		}
@@ -1567,16 +5461,54 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
 	struct hist_trigger_attrs *attrs;
 	struct event_trigger_ops *trigger_ops;
 	struct hist_trigger_data *hist_data;
-	char *trigger;
+	struct synth_event *se;
+	const char *se_name;
+	bool remove = false;
+	char *trigger, *p;
 	int ret = 0;
 
+	if (glob && strlen(glob)) {
+		last_cmd_set(param);
+		hist_err_clear();
+	}
+
 	if (!param)
 		return -EINVAL;
 
-	/* separate the trigger from the filter (k:v [if filter]) */
-	trigger = strsep(&param, " \t");
-	if (!trigger)
-		return -EINVAL;
+	if (glob[0] == '!')
+		remove = true;
+
+	/*
+	 * separate the trigger from the filter (k:v [if filter])
+	 * allowing for whitespace in the trigger
+	 */
+	p = trigger = param;
+	do {
+		p = strstr(p, "if");
+		if (!p)
+			break;
+		if (p == param)
+			return -EINVAL;
+		if (*(p - 1) != ' ' && *(p - 1) != '\t') {
+			p++;
+			continue;
+		}
+		if (p >= param + strlen(param) - strlen("if") - 1)
+			return -EINVAL;
+		if (*(p + strlen("if")) != ' ' && *(p + strlen("if")) != '\t') {
+			p++;
+			continue;
+		}
+		break;
+	} while (p);
+
+	if (!p)
+		param = NULL;
+	else {
+		*(p - 1) = '\0';
+		param = strstrip(p);
+		trigger = strstrip(trigger);
+	}
 
 	attrs = parse_hist_trigger_attrs(trigger);
 	if (IS_ERR(attrs))
@@ -1585,7 +5517,7 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
 	if (attrs->map_bits)
 		hist_trigger_bits = attrs->map_bits;
 
-	hist_data = create_hist_data(hist_trigger_bits, attrs, file);
+	hist_data = create_hist_data(hist_trigger_bits, attrs, file, remove);
 	if (IS_ERR(hist_data)) {
 		destroy_hist_trigger_attrs(attrs);
 		return PTR_ERR(hist_data);
@@ -1593,10 +5525,11 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
 
 	trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
 
-	ret = -ENOMEM;
 	trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
-	if (!trigger_data)
+	if (!trigger_data) {
+		ret = -ENOMEM;
 		goto out_free;
+	}
 
 	trigger_data->count = -1;
 	trigger_data->ops = trigger_ops;
@@ -1614,8 +5547,24 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
 			goto out_free;
 	}
 
-	if (glob[0] == '!') {
+	if (remove) {
+		if (!have_hist_trigger_match(trigger_data, file))
+			goto out_free;
+
+		if (hist_trigger_check_refs(trigger_data, file)) {
+			ret = -EBUSY;
+			goto out_free;
+		}
+
 		cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
+
+		mutex_lock(&synth_event_mutex);
+		se_name = trace_event_name(file->event_call);
+		se = find_synth_event(se_name);
+		if (se)
+			se->ref--;
+		mutex_unlock(&synth_event_mutex);
+
 		ret = 0;
 		goto out_free;
 	}
@@ -1632,14 +5581,47 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
 		goto out_free;
 	} else if (ret < 0)
 		goto out_free;
+
+	if (get_named_trigger_data(trigger_data))
+		goto enable;
+
+	if (has_hist_vars(hist_data))
+		save_hist_vars(hist_data);
+
+	ret = create_actions(hist_data, file);
+	if (ret)
+		goto out_unreg;
+
+	ret = tracing_map_init(hist_data->map);
+	if (ret)
+		goto out_unreg;
+enable:
+	ret = hist_trigger_enable(trigger_data, file);
+	if (ret)
+		goto out_unreg;
+
+	mutex_lock(&synth_event_mutex);
+	se_name = trace_event_name(file->event_call);
+	se = find_synth_event(se_name);
+	if (se)
+		se->ref++;
+	mutex_unlock(&synth_event_mutex);
+
 	/* Just return zero, not the number of registered triggers */
 	ret = 0;
  out:
+	if (ret == 0)
+		hist_err_clear();
+
 	return ret;
+ out_unreg:
+	cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
  out_free:
 	if (cmd_ops->set_filter)
 		cmd_ops->set_filter(NULL, trigger_data, NULL);
 
+	remove_hist_vars(hist_data);
+
 	kfree(trigger_data);
 
 	destroy_hist_data(hist_data);
@@ -1669,7 +5651,8 @@ __init int register_trigger_hist_cmd(void)
 }
 
 static void
-hist_enable_trigger(struct event_trigger_data *data, void *rec)
+hist_enable_trigger(struct event_trigger_data *data, void *rec,
+		    struct ring_buffer_event *event)
 {
 	struct enable_trigger_data *enable_data = data->private_data;
 	struct event_trigger_data *test;
@@ -1685,7 +5668,8 @@ hist_enable_trigger(struct event_trigger_data *data, void *rec)
 }
 
 static void
-hist_enable_count_trigger(struct event_trigger_data *data, void *rec)
+hist_enable_count_trigger(struct event_trigger_data *data, void *rec,
+			  struct ring_buffer_event *event)
 {
 	if (!data->count)
 		return;
@@ -1693,7 +5677,7 @@ hist_enable_count_trigger(struct event_trigger_data *data, void *rec)
 	if (data->count != -1)
 		(data->count)--;
 
-	hist_enable_trigger(data, rec);
+	hist_enable_trigger(data, rec, event);
 }
 
 static struct event_trigger_ops hist_enable_trigger_ops = {
@@ -1798,3 +5782,31 @@ __init int register_trigger_hist_enable_disable_cmds(void)
 
 	return ret;
 }
+
+static __init int trace_events_hist_init(void)
+{
+	struct dentry *entry = NULL;
+	struct dentry *d_tracer;
+	int err = 0;
+
+	d_tracer = tracing_init_dentry();
+	if (IS_ERR(d_tracer)) {
+		err = PTR_ERR(d_tracer);
+		goto err;
+	}
+
+	entry = tracefs_create_file("synthetic_events", 0644, d_tracer,
+				    NULL, &synth_events_fops);
+	if (!entry) {
+		err = -ENODEV;
+		goto err;
+	}
+
+	return err;
+ err:
+	pr_warn("Could not create tracefs 'synthetic_events' entry\n");
+
+	return err;
+}
+
+fs_initcall(trace_events_hist_init);
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 87411482a46f..d251cabcf69a 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -63,7 +63,8 @@ void trigger_data_free(struct event_trigger_data *data)
  * any trigger that should be deferred, ETT_NONE if nothing to defer.
  */
 enum event_trigger_type
-event_triggers_call(struct trace_event_file *file, void *rec)
+event_triggers_call(struct trace_event_file *file, void *rec,
+		    struct ring_buffer_event *event)
 {
 	struct event_trigger_data *data;
 	enum event_trigger_type tt = ETT_NONE;
@@ -76,7 +77,7 @@ event_triggers_call(struct trace_event_file *file, void *rec)
 		if (data->paused)
 			continue;
 		if (!rec) {
-			data->ops->func(data, rec);
+			data->ops->func(data, rec, event);
 			continue;
 		}
 		filter = rcu_dereference_sched(data->filter);
@@ -86,7 +87,7 @@ event_triggers_call(struct trace_event_file *file, void *rec)
 			tt |= data->cmd_ops->trigger_type;
 			continue;
 		}
-		data->ops->func(data, rec);
+		data->ops->func(data, rec, event);
 	}
 	return tt;
 }
@@ -108,7 +109,7 @@ EXPORT_SYMBOL_GPL(event_triggers_call);
 void
 event_triggers_post_call(struct trace_event_file *file,
 			 enum event_trigger_type tt,
-			 void *rec)
+			 void *rec, struct ring_buffer_event *event)
 {
 	struct event_trigger_data *data;
 
@@ -116,7 +117,7 @@ event_triggers_post_call(struct trace_event_file *file,
 		if (data->paused)
 			continue;
 		if (data->cmd_ops->trigger_type & tt)
-			data->ops->func(data, rec);
+			data->ops->func(data, rec, event);
 	}
 }
 EXPORT_SYMBOL_GPL(event_triggers_post_call);
@@ -908,8 +909,15 @@ void set_named_trigger_data(struct event_trigger_data *data,
 	data->named_data = named_data;
 }
 
+struct event_trigger_data *
+get_named_trigger_data(struct event_trigger_data *data)
+{
+	return data->named_data;
+}
+
 static void
-traceon_trigger(struct event_trigger_data *data, void *rec)
+traceon_trigger(struct event_trigger_data *data, void *rec,
+		struct ring_buffer_event *event)
 {
 	if (tracing_is_on())
 		return;
@@ -918,7 +926,8 @@ traceon_trigger(struct event_trigger_data *data, void *rec)
 }
 
 static void
-traceon_count_trigger(struct event_trigger_data *data, void *rec)
+traceon_count_trigger(struct event_trigger_data *data, void *rec,
+		      struct ring_buffer_event *event)
 {
 	if (tracing_is_on())
 		return;
@@ -933,7 +942,8 @@ traceon_count_trigger(struct event_trigger_data *data, void *rec)
 }
 
 static void
-traceoff_trigger(struct event_trigger_data *data, void *rec)
+traceoff_trigger(struct event_trigger_data *data, void *rec,
+		 struct ring_buffer_event *event)
 {
 	if (!tracing_is_on())
 		return;
@@ -942,7 +952,8 @@ traceoff_trigger(struct event_trigger_data *data, void *rec)
 }
 
 static void
-traceoff_count_trigger(struct event_trigger_data *data, void *rec)
+traceoff_count_trigger(struct event_trigger_data *data, void *rec,
+		       struct ring_buffer_event *event)
 {
 	if (!tracing_is_on())
 		return;
@@ -1039,13 +1050,15 @@ static struct event_command trigger_traceoff_cmd = {
 
 #ifdef CONFIG_TRACER_SNAPSHOT
 static void
-snapshot_trigger(struct event_trigger_data *data, void *rec)
+snapshot_trigger(struct event_trigger_data *data, void *rec,
+		 struct ring_buffer_event *event)
 {
 	tracing_snapshot();
 }
 
 static void
-snapshot_count_trigger(struct event_trigger_data *data, void *rec)
+snapshot_count_trigger(struct event_trigger_data *data, void *rec,
+		       struct ring_buffer_event *event)
 {
 	if (!data->count)
 		return;
@@ -1053,7 +1066,7 @@ snapshot_count_trigger(struct event_trigger_data *data, void *rec)
 	if (data->count != -1)
 		(data->count)--;
 
-	snapshot_trigger(data, rec);
+	snapshot_trigger(data, rec, event);
 }
 
 static int
@@ -1141,13 +1154,15 @@ static __init int register_trigger_snapshot_cmd(void) { return 0; }
 #endif
 
 static void
-stacktrace_trigger(struct event_trigger_data *data, void *rec)
+stacktrace_trigger(struct event_trigger_data *data, void *rec,
+		   struct ring_buffer_event *event)
 {
 	trace_dump_stack(STACK_SKIP);
 }
 
 static void
-stacktrace_count_trigger(struct event_trigger_data *data, void *rec)
+stacktrace_count_trigger(struct event_trigger_data *data, void *rec,
+			 struct ring_buffer_event *event)
 {
 	if (!data->count)
 		return;
@@ -1155,7 +1170,7 @@ stacktrace_count_trigger(struct event_trigger_data *data, void *rec)
 	if (data->count != -1)
 		(data->count)--;
 
-	stacktrace_trigger(data, rec);
+	stacktrace_trigger(data, rec, event);
 }
 
 static int
@@ -1217,7 +1232,8 @@ static __init void unregister_trigger_traceon_traceoff_cmds(void)
 }
 
 static void
-event_enable_trigger(struct event_trigger_data *data, void *rec)
+event_enable_trigger(struct event_trigger_data *data, void *rec,
+		     struct ring_buffer_event *event)
 {
 	struct enable_trigger_data *enable_data = data->private_data;
 
@@ -1228,7 +1244,8 @@ event_enable_trigger(struct event_trigger_data *data, void *rec)
 }
 
 static void
-event_enable_count_trigger(struct event_trigger_data *data, void *rec)
+event_enable_count_trigger(struct event_trigger_data *data, void *rec,
+			   struct ring_buffer_event *event)
 {
 	struct enable_trigger_data *enable_data = data->private_data;
 
@@ -1242,7 +1259,7 @@ event_enable_count_trigger(struct event_trigger_data *data, void *rec)
 	if (data->count != -1)
 		(data->count)--;
 
-	event_enable_trigger(data, rec);
+	event_enable_trigger(data, rec, event);
 }
 
 int event_enable_trigger_print(struct seq_file *m,
diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c
index 07e75344725b..5cadb1b8b5fe 100644
--- a/kernel/trace/tracing_map.c
+++ b/kernel/trace/tracing_map.c
@@ -66,6 +66,73 @@ u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i)
 	return (u64)atomic64_read(&elt->fields[i].sum);
 }
 
+/**
+ * tracing_map_set_var - Assign a tracing_map_elt's variable field
+ * @elt: The tracing_map_elt
+ * @i: The index of the given variable associated with the tracing_map_elt
+ * @n: The value to assign
+ *
+ * Assign n to variable i associated with the specified tracing_map_elt
+ * instance.  The index i is the index returned by the call to
+ * tracing_map_add_var() when the tracing map was set up.
+ */
+void tracing_map_set_var(struct tracing_map_elt *elt, unsigned int i, u64 n)
+{
+	atomic64_set(&elt->vars[i], n);
+	elt->var_set[i] = true;
+}
+
+/**
+ * tracing_map_var_set - Return whether or not a variable has been set
+ * @elt: The tracing_map_elt
+ * @i: The index of the given variable associated with the tracing_map_elt
+ *
+ * Return true if the variable has been set, false otherwise.  The
+ * index i is the index returned by the call to tracing_map_add_var()
+ * when the tracing map was set up.
+ */
+bool tracing_map_var_set(struct tracing_map_elt *elt, unsigned int i)
+{
+	return elt->var_set[i];
+}
+
+/**
+ * tracing_map_read_var - Return the value of a tracing_map_elt's variable field
+ * @elt: The tracing_map_elt
+ * @i: The index of the given variable associated with the tracing_map_elt
+ *
+ * Retrieve the value of the variable i associated with the specified
+ * tracing_map_elt instance.  The index i is the index returned by the
+ * call to tracing_map_add_var() when the tracing map was set
+ * up.
+ *
+ * Return: The variable value associated with field i for elt.
+ */
+u64 tracing_map_read_var(struct tracing_map_elt *elt, unsigned int i)
+{
+	return (u64)atomic64_read(&elt->vars[i]);
+}
+
+/**
+ * tracing_map_read_var_once - Return and reset a tracing_map_elt's variable field
+ * @elt: The tracing_map_elt
+ * @i: The index of the given variable associated with the tracing_map_elt
+ *
+ * Retrieve the value of the variable i associated with the specified
+ * tracing_map_elt instance, and reset the variable to the 'not set'
+ * state.  The index i is the index returned by the call to
+ * tracing_map_add_var() when the tracing map was set up.  The reset
+ * essentially makes the variable a read-once variable if it's only
+ * accessed using this function.
+ *
+ * Return: The variable value associated with field i for elt.
+ */
+u64 tracing_map_read_var_once(struct tracing_map_elt *elt, unsigned int i)
+{
+	elt->var_set[i] = false;
+	return (u64)atomic64_read(&elt->vars[i]);
+}
+
 int tracing_map_cmp_string(void *val_a, void *val_b)
 {
 	char *a = val_a;
@@ -171,6 +238,28 @@ int tracing_map_add_sum_field(struct tracing_map *map)
 }
 
 /**
+ * tracing_map_add_var - Add a field describing a tracing_map var
+ * @map: The tracing_map
+ *
+ * Add a var to the map and return the index identifying it in the map
+ * and associated tracing_map_elts.  This is the index used for
+ * instance to update a var for a particular tracing_map_elt using
+ * tracing_map_update_var() or reading it via tracing_map_read_var().
+ *
+ * Return: The index identifying the var in the map and associated
+ * tracing_map_elts, or -EINVAL on error.
+ */
+int tracing_map_add_var(struct tracing_map *map)
+{
+	int ret = -EINVAL;
+
+	if (map->n_vars < TRACING_MAP_VARS_MAX)
+		ret = map->n_vars++;
+
+	return ret;
+}
+
+/**
  * tracing_map_add_key_field - Add a field describing a tracing_map key
  * @map: The tracing_map
  * @offset: The offset within the key
@@ -280,6 +369,11 @@ static void tracing_map_elt_clear(struct tracing_map_elt *elt)
 		if (elt->fields[i].cmp_fn == tracing_map_cmp_atomic64)
 			atomic64_set(&elt->fields[i].sum, 0);
 
+	for (i = 0; i < elt->map->n_vars; i++) {
+		atomic64_set(&elt->vars[i], 0);
+		elt->var_set[i] = false;
+	}
+
 	if (elt->map->ops && elt->map->ops->elt_clear)
 		elt->map->ops->elt_clear(elt);
 }
@@ -306,6 +400,8 @@ static void tracing_map_elt_free(struct tracing_map_elt *elt)
 	if (elt->map->ops && elt->map->ops->elt_free)
 		elt->map->ops->elt_free(elt);
 	kfree(elt->fields);
+	kfree(elt->vars);
+	kfree(elt->var_set);
 	kfree(elt->key);
 	kfree(elt);
 }
@@ -333,6 +429,18 @@ static struct tracing_map_elt *tracing_map_elt_alloc(struct tracing_map *map)
 		goto free;
 	}
 
+	elt->vars = kcalloc(map->n_vars, sizeof(*elt->vars), GFP_KERNEL);
+	if (!elt->vars) {
+		err = -ENOMEM;
+		goto free;
+	}
+
+	elt->var_set = kcalloc(map->n_vars, sizeof(*elt->var_set), GFP_KERNEL);
+	if (!elt->var_set) {
+		err = -ENOMEM;
+		goto free;
+	}
+
 	tracing_map_elt_init_fields(elt);
 
 	if (map->ops && map->ops->elt_alloc) {
@@ -414,7 +522,9 @@ static inline struct tracing_map_elt *
 __tracing_map_insert(struct tracing_map *map, void *key, bool lookup_only)
 {
 	u32 idx, key_hash, test_key;
+	int dup_try = 0;
 	struct tracing_map_entry *entry;
+	struct tracing_map_elt *val;
 
 	key_hash = jhash(key, map->key_size, 0);
 	if (key_hash == 0)
@@ -426,11 +536,33 @@ __tracing_map_insert(struct tracing_map *map, void *key, bool lookup_only)
 		entry = TRACING_MAP_ENTRY(map->map, idx);
 		test_key = entry->key;
 
-		if (test_key && test_key == key_hash && entry->val &&
-		    keys_match(key, entry->val->key, map->key_size)) {
-			if (!lookup_only)
-				atomic64_inc(&map->hits);
-			return entry->val;
+		if (test_key && test_key == key_hash) {
+			val = READ_ONCE(entry->val);
+			if (val &&
+			    keys_match(key, val->key, map->key_size)) {
+				if (!lookup_only)
+					atomic64_inc(&map->hits);
+				return val;
+			} else if (unlikely(!val)) {
+				/*
+				 * The key is present. But, val (pointer to elt
+				 * struct) is still NULL. which means some other
+				 * thread is in the process of inserting an
+				 * element.
+				 *
+				 * On top of that, it's key_hash is same as the
+				 * one being inserted right now. So, it's
+				 * possible that the element has the same
+				 * key as well.
+				 */
+
+				dup_try++;
+				if (dup_try > map->map_size) {
+					atomic64_inc(&map->drops);
+					break;
+				}
+				continue;
+			}
 		}
 
 		if (!test_key) {
@@ -452,6 +584,13 @@ __tracing_map_insert(struct tracing_map *map, void *key, bool lookup_only)
 				atomic64_inc(&map->hits);
 
 				return entry->val;
+			} else {
+				/*
+				 * cmpxchg() failed. Loop around once
+				 * more to check what key was inserted.
+				 */
+				dup_try++;
+				continue;
 			}
 		}
 
@@ -816,67 +955,15 @@ create_sort_entry(void *key, struct tracing_map_elt *elt)
 	return sort_entry;
 }
 
-static struct tracing_map_elt *copy_elt(struct tracing_map_elt *elt)
-{
-	struct tracing_map_elt *dup_elt;
-	unsigned int i;
-
-	dup_elt = tracing_map_elt_alloc(elt->map);
-	if (IS_ERR(dup_elt))
-		return NULL;
-
-	if (elt->map->ops && elt->map->ops->elt_copy)
-		elt->map->ops->elt_copy(dup_elt, elt);
-
-	dup_elt->private_data = elt->private_data;
-	memcpy(dup_elt->key, elt->key, elt->map->key_size);
-
-	for (i = 0; i < elt->map->n_fields; i++) {
-		atomic64_set(&dup_elt->fields[i].sum,
-			     atomic64_read(&elt->fields[i].sum));
-		dup_elt->fields[i].cmp_fn = elt->fields[i].cmp_fn;
-	}
-
-	return dup_elt;
-}
-
-static int merge_dup(struct tracing_map_sort_entry **sort_entries,
-		     unsigned int target, unsigned int dup)
-{
-	struct tracing_map_elt *target_elt, *elt;
-	bool first_dup = (target - dup) == 1;
-	int i;
-
-	if (first_dup) {
-		elt = sort_entries[target]->elt;
-		target_elt = copy_elt(elt);
-		if (!target_elt)
-			return -ENOMEM;
-		sort_entries[target]->elt = target_elt;
-		sort_entries[target]->elt_copied = true;
-	} else
-		target_elt = sort_entries[target]->elt;
-
-	elt = sort_entries[dup]->elt;
-
-	for (i = 0; i < elt->map->n_fields; i++)
-		atomic64_add(atomic64_read(&elt->fields[i].sum),
-			     &target_elt->fields[i].sum);
-
-	sort_entries[dup]->dup = true;
-
-	return 0;
-}
-
-static int merge_dups(struct tracing_map_sort_entry **sort_entries,
+static void detect_dups(struct tracing_map_sort_entry **sort_entries,
 		      int n_entries, unsigned int key_size)
 {
 	unsigned int dups = 0, total_dups = 0;
-	int err, i, j;
+	int i;
 	void *key;
 
 	if (n_entries < 2)
-		return total_dups;
+		return;
 
 	sort(sort_entries, n_entries, sizeof(struct tracing_map_sort_entry *),
 	     (int (*)(const void *, const void *))cmp_entries_dup, NULL);
@@ -885,30 +972,14 @@ static int merge_dups(struct tracing_map_sort_entry **sort_entries,
 	for (i = 1; i < n_entries; i++) {
 		if (!memcmp(sort_entries[i]->key, key, key_size)) {
 			dups++; total_dups++;
-			err = merge_dup(sort_entries, i - dups, i);
-			if (err)
-				return err;
 			continue;
 		}
 		key = sort_entries[i]->key;
 		dups = 0;
 	}
 
-	if (!total_dups)
-		return total_dups;
-
-	for (i = 0, j = 0; i < n_entries; i++) {
-		if (!sort_entries[i]->dup) {
-			sort_entries[j] = sort_entries[i];
-			if (j++ != i)
-				sort_entries[i] = NULL;
-		} else {
-			destroy_sort_entry(sort_entries[i]);
-			sort_entries[i] = NULL;
-		}
-	}
-
-	return total_dups;
+	WARN_ONCE(total_dups > 0,
+		  "Duplicates detected: %d\n", total_dups);
 }
 
 static bool is_key(struct tracing_map *map, unsigned int field_idx)
@@ -1034,10 +1105,7 @@ int tracing_map_sort_entries(struct tracing_map *map,
 		return 1;
 	}
 
-	ret = merge_dups(entries, n_entries, map->key_size);
-	if (ret < 0)
-		goto free;
-	n_entries -= ret;
+	detect_dups(entries, n_entries, map->key_size);
 
 	if (is_key(map, sort_keys[0].field_idx))
 		cmp_entries_fn = cmp_entries_key;
diff --git a/kernel/trace/tracing_map.h b/kernel/trace/tracing_map.h
index 5b5bbf8ae550..053eb92b2d31 100644
--- a/kernel/trace/tracing_map.h
+++ b/kernel/trace/tracing_map.h
@@ -10,6 +10,7 @@
 #define TRACING_MAP_VALS_MAX		3
 #define TRACING_MAP_FIELDS_MAX		(TRACING_MAP_KEYS_MAX + \
 					 TRACING_MAP_VALS_MAX)
+#define TRACING_MAP_VARS_MAX		16
 #define TRACING_MAP_SORT_KEYS_MAX	2
 
 typedef int (*tracing_map_cmp_fn_t) (void *val_a, void *val_b);
@@ -137,6 +138,8 @@ struct tracing_map_field {
 struct tracing_map_elt {
 	struct tracing_map		*map;
 	struct tracing_map_field	*fields;
+	atomic64_t			*vars;
+	bool				*var_set;
 	void				*key;
 	void				*private_data;
 };
@@ -192,6 +195,7 @@ struct tracing_map {
 	int				key_idx[TRACING_MAP_KEYS_MAX];
 	unsigned int			n_keys;
 	struct tracing_map_sort_key	sort_key;
+	unsigned int			n_vars;
 	atomic64_t			hits;
 	atomic64_t			drops;
 };
@@ -215,11 +219,6 @@ struct tracing_map {
  *	Element allocation occurs before tracing begins, when the
  *	tracing_map_init() call is made by client code.
  *
- * @elt_copy: At certain points in the lifetime of an element, it may
- *	need to be copied.  The copy should include a copy of the
- *	client-allocated data, which can be copied into the 'to'
- *	element from the 'from' element.
- *
  * @elt_free: When a tracing_map_elt is freed, this function is called
  *	and allows client-allocated per-element data to be freed.
  *
@@ -233,8 +232,6 @@ struct tracing_map {
  */
 struct tracing_map_ops {
 	int			(*elt_alloc)(struct tracing_map_elt *elt);
-	void			(*elt_copy)(struct tracing_map_elt *to,
-					    struct tracing_map_elt *from);
 	void			(*elt_free)(struct tracing_map_elt *elt);
 	void			(*elt_clear)(struct tracing_map_elt *elt);
 	void			(*elt_init)(struct tracing_map_elt *elt);
@@ -248,6 +245,7 @@ tracing_map_create(unsigned int map_bits,
 extern int tracing_map_init(struct tracing_map *map);
 
 extern int tracing_map_add_sum_field(struct tracing_map *map);
+extern int tracing_map_add_var(struct tracing_map *map);
 extern int tracing_map_add_key_field(struct tracing_map *map,
 				     unsigned int offset,
 				     tracing_map_cmp_fn_t cmp_fn);
@@ -267,7 +265,13 @@ extern int tracing_map_cmp_none(void *val_a, void *val_b);
 
 extern void tracing_map_update_sum(struct tracing_map_elt *elt,
 				   unsigned int i, u64 n);
+extern void tracing_map_set_var(struct tracing_map_elt *elt,
+				unsigned int i, u64 n);
+extern bool tracing_map_var_set(struct tracing_map_elt *elt, unsigned int i);
 extern u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i);
+extern u64 tracing_map_read_var(struct tracing_map_elt *elt, unsigned int i);
+extern u64 tracing_map_read_var_once(struct tracing_map_elt *elt, unsigned int i);
+
 extern void tracing_map_set_field_descr(struct tracing_map *map,
 					unsigned int i,
 					unsigned int key_offset,