1 files changed, 338 insertions, 34 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c3b2c7dfadef..b4f348b4653f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -482,7 +482,7 @@ EXPORT_SYMBOL_GPL(unregister_ftrace_export);
 	 TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO |		\
 	 TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE |			\
 	 TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS |			\
-	 TRACE_ITER_HASH_PTR)
+	 TRACE_ITER_HASH_PTR | TRACE_ITER_TRACE_PRINTK)
 
 /* trace_options that are only supported by global_trace */
 #define TOP_LEVEL_TRACE_FLAGS (TRACE_ITER_PRINTK |			\
@@ -490,7 +490,7 @@ EXPORT_SYMBOL_GPL(unregister_ftrace_export);
 
 /* trace_flags that are default zero for instances */
 #define ZEROED_TRACE_FLAGS \
-	(TRACE_ITER_EVENT_FORK | TRACE_ITER_FUNC_FORK)
+	(TRACE_ITER_EVENT_FORK | TRACE_ITER_FUNC_FORK | TRACE_ITER_TRACE_PRINTK)
 
 /*
  * The global_trace is the descriptor that holds the top-level tracing
@@ -500,6 +500,29 @@ static struct trace_array global_trace = {
 	.trace_flags = TRACE_DEFAULT_FLAGS,
 };
 
+static struct trace_array *printk_trace = &global_trace;
+
+static __always_inline bool printk_binsafe(struct trace_array *tr)
+{
+	/*
+	 * The binary format of traceprintk can cause a crash if used
+	 * by a buffer from another boot. Force the use of the
+	 * non binary version of trace_printk if the trace_printk
+	 * buffer is a boot mapped ring buffer.
+	 */
+	return !(tr->flags & TRACE_ARRAY_FL_BOOT);
+}
+
+static void update_printk_trace(struct trace_array *tr)
+{
+	if (printk_trace == tr)
+		return;
+
+	printk_trace->trace_flags &= ~TRACE_ITER_TRACE_PRINTK;
+	printk_trace = tr;
+	tr->trace_flags |= TRACE_ITER_TRACE_PRINTK;
+}
+
 void trace_set_ring_buffer_expanded(struct trace_array *tr)
 {
 	if (!tr)
@@ -1117,7 +1140,7 @@ EXPORT_SYMBOL_GPL(__trace_array_puts);
  */
 int __trace_puts(unsigned long ip, const char *str, int size)
 {
-	return __trace_array_puts(&global_trace, ip, str, size);
+	return __trace_array_puts(printk_trace, ip, str, size);
 }
 EXPORT_SYMBOL_GPL(__trace_puts);
 
@@ -1128,6 +1151,7 @@ EXPORT_SYMBOL_GPL(__trace_puts);
  */
 int __trace_bputs(unsigned long ip, const char *str)
 {
+	struct trace_array *tr = READ_ONCE(printk_trace);
 	struct ring_buffer_event *event;
 	struct trace_buffer *buffer;
 	struct bputs_entry *entry;
@@ -1135,14 +1159,17 @@ int __trace_bputs(unsigned long ip, const char *str)
 	int size = sizeof(struct bputs_entry);
 	int ret = 0;
 
-	if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
+	if (!printk_binsafe(tr))
+		return __trace_puts(ip, str, strlen(str));
+
+	if (!(tr->trace_flags & TRACE_ITER_PRINTK))
 		return 0;
 
 	if (unlikely(tracing_selftest_running || tracing_disabled))
 		return 0;
 
 	trace_ctx = tracing_gen_ctx();
-	buffer = global_trace.array_buffer.buffer;
+	buffer = tr->array_buffer.buffer;
 
 	ring_buffer_nest_start(buffer);
 	event = __trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size,
@@ -1155,7 +1182,7 @@ int __trace_bputs(unsigned long ip, const char *str)
 	entry->str			= str;
 
 	__buffer_unlock_commit(buffer, event);
-	ftrace_trace_stack(&global_trace, buffer, trace_ctx, 4, NULL);
+	ftrace_trace_stack(tr, buffer, trace_ctx, 4, NULL);
 
 	ret = 1;
  out:
@@ -3021,7 +3048,7 @@ void trace_dump_stack(int skip)
 	/* Skip 1 to skip this function. */
 	skip++;
 #endif
-	__ftrace_trace_stack(global_trace.array_buffer.buffer,
+	__ftrace_trace_stack(printk_trace->array_buffer.buffer,
 			     tracing_gen_ctx(), skip, NULL);
 }
 EXPORT_SYMBOL_GPL(trace_dump_stack);
@@ -3240,12 +3267,15 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
 	struct trace_event_call *call = &event_bprint;
 	struct ring_buffer_event *event;
 	struct trace_buffer *buffer;
-	struct trace_array *tr = &global_trace;
+	struct trace_array *tr = READ_ONCE(printk_trace);
 	struct bprint_entry *entry;
 	unsigned int trace_ctx;
 	char *tbuffer;
 	int len = 0, size;
 
+	if (!printk_binsafe(tr))
+		return trace_vprintk(ip, fmt, args);
+
 	if (unlikely(tracing_selftest_running || tracing_disabled))
 		return 0;
 
@@ -3338,7 +3368,7 @@ __trace_array_vprintk(struct trace_buffer *buffer,
 	memcpy(&entry->buf, tbuffer, len + 1);
 	if (!call_filter_check_discard(call, entry, buffer, event)) {
 		__buffer_unlock_commit(buffer, event);
-		ftrace_trace_stack(&global_trace, buffer, trace_ctx, 6, NULL);
+		ftrace_trace_stack(printk_trace, buffer, trace_ctx, 6, NULL);
 	}
 
 out:
@@ -3434,7 +3464,7 @@ int trace_array_printk_buf(struct trace_buffer *buffer,
 	int ret;
 	va_list ap;
 
-	if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
+	if (!(printk_trace->trace_flags & TRACE_ITER_PRINTK))
 		return 0;
 
 	va_start(ap, fmt);
@@ -3446,7 +3476,7 @@ int trace_array_printk_buf(struct trace_buffer *buffer,
 __printf(2, 0)
 int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
 {
-	return trace_array_vprintk(&global_trace, ip, fmt, args);
+	return trace_array_vprintk(printk_trace, ip, fmt, args);
 }
 EXPORT_SYMBOL_GPL(trace_vprintk);
 
@@ -3667,8 +3697,11 @@ static void test_can_verify(void)
 void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 			 va_list ap)
 {
+	long text_delta = iter->tr->text_delta;
+	long data_delta = iter->tr->data_delta;
 	const char *p = fmt;
 	const char *str;
+	bool good;
 	int i, j;
 
 	if (WARN_ON_ONCE(!fmt))
@@ -3687,7 +3720,10 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 
 		j = 0;
 
-		/* We only care about %s and variants */
+		/*
+		 * We only care about %s and variants
+		 * as well as %p[sS] if delta is non-zero
+		 */
 		for (i = 0; p[i]; i++) {
 			if (i + 1 >= iter->fmt_size) {
 				/*
@@ -3716,6 +3752,11 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 				}
 				if (p[i+j] == 's')
 					break;
+
+				if (text_delta && p[i+1] == 'p' &&
+				    ((p[i+2] == 's' || p[i+2] == 'S')))
+					break;
+
 				star = false;
 			}
 			j = 0;
@@ -3729,6 +3770,24 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 		iter->fmt[i] = '\0';
 		trace_seq_vprintf(&iter->seq, iter->fmt, ap);
 
+		/* Add delta to %pS pointers */
+		if (p[i+1] == 'p') {
+			unsigned long addr;
+			char fmt[4];
+
+			fmt[0] = '%';
+			fmt[1] = 'p';
+			fmt[2] = p[i+2]; /* Either %ps or %pS */
+			fmt[3] = '\0';
+
+			addr = va_arg(ap, unsigned long);
+			addr += text_delta;
+			trace_seq_printf(&iter->seq, fmt, (void *)addr);
+
+			p += i + 3;
+			continue;
+		}
+
 		/*
 		 * If iter->seq is full, the above call no longer guarantees
 		 * that ap is in sync with fmt processing, and further calls
@@ -3747,6 +3806,14 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 		/* The ap now points to the string data of the %s */
 		str = va_arg(ap, const char *);
 
+		good = trace_safe_str(iter, str, star, len);
+
+		/* Could be from the last boot */
+		if (data_delta && !good) {
+			str += data_delta;
+			good = trace_safe_str(iter, str, star, len);
+		}
+
 		/*
 		 * If you hit this warning, it is likely that the
 		 * trace event in question used %s on a string that
@@ -3756,8 +3823,7 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
 		 * instead. See samples/trace_events/trace-events-sample.h
 		 * for reference.
 		 */
-		if (WARN_ONCE(!trace_safe_str(iter, str, star, len),
-			      "fmt: '%s' current_buffer: '%s'",
+		if (WARN_ONCE(!good, "fmt: '%s' current_buffer: '%s'",
 			      fmt, seq_buf_str(&iter->seq.seq))) {
 			int ret;
 
@@ -4919,6 +4985,11 @@ static int tracing_open(struct inode *inode, struct file *file)
 static bool
 trace_ok_for_array(struct tracer *t, struct trace_array *tr)
 {
+#ifdef CONFIG_TRACER_SNAPSHOT
+	/* arrays with mapped buffer range do not have snapshots */
+	if (tr->range_addr_start && t->use_max_tr)
+		return false;
+#endif
 	return (tr->flags & TRACE_ARRAY_FL_GLOBAL) || t->allow_instances;
 }
 
@@ -5011,7 +5082,7 @@ static int show_traces_open(struct inode *inode, struct file *file)
 	return 0;
 }
 
-static int show_traces_release(struct inode *inode, struct file *file)
+static int tracing_seq_release(struct inode *inode, struct file *file)
 {
 	struct trace_array *tr = inode->i_private;
 
@@ -5052,7 +5123,7 @@ static const struct file_operations show_traces_fops = {
 	.open		= show_traces_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
-	.release	= show_traces_release,
+	.release	= tracing_seq_release,
 };
 
 static ssize_t
@@ -5237,7 +5308,8 @@ int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set)
 int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
 {
 	if ((mask == TRACE_ITER_RECORD_TGID) ||
-	    (mask == TRACE_ITER_RECORD_CMD))
+	    (mask == TRACE_ITER_RECORD_CMD) ||
+	    (mask == TRACE_ITER_TRACE_PRINTK))
 		lockdep_assert_held(&event_mutex);
 
 	/* do nothing if flag is already set */
@@ -5249,6 +5321,25 @@ int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
 		if (tr->current_trace->flag_changed(tr, mask, !!enabled))
 			return -EINVAL;
 
+	if (mask == TRACE_ITER_TRACE_PRINTK) {
+		if (enabled) {
+			update_printk_trace(tr);
+		} else {
+			/*
+			 * The global_trace cannot clear this.
+			 * It's flag only gets cleared if another instance sets it.
+			 */
+			if (printk_trace == &global_trace)
+				return -EINVAL;
+			/*
+			 * An instance must always have it set.
+			 * by default, that's the global_trace instane.
+			 */
+			if (printk_trace == tr)
+				update_printk_trace(&global_trace);
+		}
+	}
+
 	if (enabled)
 		tr->trace_flags |= mask;
 	else
@@ -6034,6 +6125,18 @@ out:
 	return ret;
 }
 
+static void update_last_data(struct trace_array *tr)
+{
+	if (!tr->text_delta && !tr->data_delta)
+		return;
+
+	/* Clear old data */
+	tracing_reset_online_cpus(&tr->array_buffer);
+
+	/* Using current data now */
+	tr->text_delta = 0;
+	tr->data_delta = 0;
+}
 
 /**
  * tracing_update_buffers - used by tracing facility to expand ring buffers
@@ -6051,6 +6154,9 @@ int tracing_update_buffers(struct trace_array *tr)
 	int ret = 0;
 
 	mutex_lock(&trace_types_lock);
+
+	update_last_data(tr);
+
 	if (!tr->ring_buffer_expanded)
 		ret = __tracing_resize_ring_buffer(tr, trace_buf_size,
 						RING_BUFFER_ALL_CPUS);
@@ -6106,6 +6212,8 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf)
 
 	mutex_lock(&trace_types_lock);
 
+	update_last_data(tr);
+
 	if (!tr->ring_buffer_expanded) {
 		ret = __tracing_resize_ring_buffer(tr, trace_buf_size,
 						RING_BUFFER_ALL_CPUS);
@@ -6854,6 +6962,37 @@ tracing_total_entries_read(struct file *filp, char __user *ubuf,
 }
 
 static ssize_t
+tracing_last_boot_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+	struct trace_array *tr = filp->private_data;
+	struct seq_buf seq;
+	char buf[64];
+
+	seq_buf_init(&seq, buf, 64);
+
+	seq_buf_printf(&seq, "text delta:\t%ld\n", tr->text_delta);
+	seq_buf_printf(&seq, "data delta:\t%ld\n", tr->data_delta);
+
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, seq_buf_used(&seq));
+}
+
+static int tracing_buffer_meta_open(struct inode *inode, struct file *filp)
+{
+	struct trace_array *tr = inode->i_private;
+	int cpu = tracing_get_cpu(inode);
+	int ret;
+
+	ret = tracing_check_open_get_tr(tr);
+	if (ret)
+		return ret;
+
+	ret = ring_buffer_meta_seq_init(filp, tr->array_buffer.buffer, cpu);
+	if (ret < 0)
+		__trace_array_put(tr);
+	return ret;
+}
+
+static ssize_t
 tracing_free_buffer_write(struct file *filp, const char __user *ubuf,
 			  size_t cnt, loff_t *ppos)
 {
@@ -7429,6 +7568,13 @@ static const struct file_operations tracing_entries_fops = {
 	.release	= tracing_release_generic_tr,
 };
 
+static const struct file_operations tracing_buffer_meta_fops = {
+	.open		= tracing_buffer_meta_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= tracing_seq_release,
+};
+
 static const struct file_operations tracing_total_entries_fops = {
 	.open		= tracing_open_generic_tr,
 	.read		= tracing_total_entries_read,
@@ -7469,6 +7615,13 @@ static const struct file_operations trace_time_stamp_mode_fops = {
 	.release	= tracing_single_release_tr,
 };
 
+static const struct file_operations last_boot_fops = {
+	.open		= tracing_open_generic_tr,
+	.read		= tracing_last_boot_read,
+	.llseek		= generic_file_llseek,
+	.release	= tracing_release_generic_tr,
+};
+
 #ifdef CONFIG_TRACER_SNAPSHOT
 static const struct file_operations snapshot_fops = {
 	.open		= tracing_snapshot_open,
@@ -8661,12 +8814,17 @@ tracing_init_tracefs_percpu(struct trace_array *tr, long cpu)
 	trace_create_cpu_file("buffer_size_kb", TRACE_MODE_READ, d_cpu,
 				tr, cpu, &tracing_entries_fops);
 
+	if (tr->range_addr_start)
+		trace_create_cpu_file("buffer_meta", TRACE_MODE_READ, d_cpu,
+				      tr, cpu, &tracing_buffer_meta_fops);
 #ifdef CONFIG_TRACER_SNAPSHOT
-	trace_create_cpu_file("snapshot", TRACE_MODE_WRITE, d_cpu,
-				tr, cpu, &snapshot_fops);
+	if (!tr->range_addr_start) {
+		trace_create_cpu_file("snapshot", TRACE_MODE_WRITE, d_cpu,
+				      tr, cpu, &snapshot_fops);
 
-	trace_create_cpu_file("snapshot_raw", TRACE_MODE_READ, d_cpu,
-				tr, cpu, &snapshot_raw_fops);
+		trace_create_cpu_file("snapshot_raw", TRACE_MODE_READ, d_cpu,
+				      tr, cpu, &snapshot_raw_fops);
+	}
 #endif
 }
 
@@ -9203,7 +9361,21 @@ allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int size
 
 	buf->tr = tr;
 
-	buf->buffer = ring_buffer_alloc(size, rb_flags);
+	if (tr->range_addr_start && tr->range_addr_size) {
+		buf->buffer = ring_buffer_alloc_range(size, rb_flags, 0,
+						      tr->range_addr_start,
+						      tr->range_addr_size);
+
+		ring_buffer_last_boot_delta(buf->buffer,
+					    &tr->text_delta, &tr->data_delta);
+		/*
+		 * This is basically the same as a mapped buffer,
+		 * with the same restrictions.
+		 */
+		tr->mapped++;
+	} else {
+		buf->buffer = ring_buffer_alloc(size, rb_flags);
+	}
 	if (!buf->buffer)
 		return -ENOMEM;
 
@@ -9240,6 +9412,10 @@ static int allocate_trace_buffers(struct trace_array *tr, int size)
 		return ret;
 
 #ifdef CONFIG_TRACER_MAX_TRACE
+	/* Fix mapped buffer trace arrays do not have snapshot buffers */
+	if (tr->range_addr_start)
+		return 0;
+
 	ret = allocate_trace_buffer(tr, &tr->max_buffer,
 				    allocate_snapshot ? size : 1);
 	if (MEM_FAIL(ret, "Failed to allocate trace buffer\n")) {
@@ -9340,7 +9516,9 @@ static int trace_array_create_dir(struct trace_array *tr)
 }
 
 static struct trace_array *
-trace_array_create_systems(const char *name, const char *systems)
+trace_array_create_systems(const char *name, const char *systems,
+			   unsigned long range_addr_start,
+			   unsigned long range_addr_size)
 {
 	struct trace_array *tr;
 	int ret;
@@ -9366,6 +9544,10 @@ trace_array_create_systems(const char *name, const char *systems)
 			goto out_free_tr;
 	}
 
+	/* Only for boot up memory mapped ring buffers */
+	tr->range_addr_start = range_addr_start;
+	tr->range_addr_size = range_addr_size;
+
 	tr->trace_flags = global_trace.trace_flags & ~ZEROED_TRACE_FLAGS;
 
 	cpumask_copy(tr->tracing_cpumask, cpu_all_mask);
@@ -9423,7 +9605,7 @@ trace_array_create_systems(const char *name, const char *systems)
 
 static struct trace_array *trace_array_create(const char *name)
 {
-	return trace_array_create_systems(name, NULL);
+	return trace_array_create_systems(name, NULL, 0, 0);
 }
 
 static int instance_mkdir(const char *name)
@@ -9448,6 +9630,31 @@ out_unlock:
 	return ret;
 }
 
+static u64 map_pages(u64 start, u64 size)
+{
+	struct page **pages;
+	phys_addr_t page_start;
+	unsigned int page_count;
+	unsigned int i;
+	void *vaddr;
+
+	page_count = DIV_ROUND_UP(size, PAGE_SIZE);
+
+	page_start = start;
+	pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
+	if (!pages)
+		return 0;
+
+	for (i = 0; i < page_count; i++) {
+		phys_addr_t addr = page_start + i * PAGE_SIZE;
+		pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
+	}
+	vaddr = vmap(pages, page_count, VM_MAP, PAGE_KERNEL);
+	kfree(pages);
+
+	return (u64)(unsigned long)vaddr;
+}
+
 /**
  * trace_array_get_by_name - Create/Lookup a trace array, given its name.
  * @name: The name of the trace array to be looked up/created.
@@ -9477,7 +9684,7 @@ struct trace_array *trace_array_get_by_name(const char *name, const char *system
 			goto out_unlock;
 	}
 
-	tr = trace_array_create_systems(name, systems);
+	tr = trace_array_create_systems(name, systems, 0, 0);
 
 	if (IS_ERR(tr))
 		tr = NULL;
@@ -9507,6 +9714,9 @@ static int __remove_instance(struct trace_array *tr)
 			set_tracer_flag(tr, 1 << i, 0);
 	}
 
+	if (printk_trace == tr)
+		update_printk_trace(&global_trace);
+
 	tracing_set_nop(tr);
 	clear_ftrace_function_probes(tr);
 	event_trace_del_tracer(tr);
@@ -9669,10 +9879,15 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 	if (ftrace_create_function_files(tr, d_tracer))
 		MEM_FAIL(1, "Could not allocate function filter files");
 
+	if (tr->range_addr_start) {
+		trace_create_file("last_boot_info", TRACE_MODE_READ, d_tracer,
+				  tr, &last_boot_fops);
 #ifdef CONFIG_TRACER_SNAPSHOT
-	trace_create_file("snapshot", TRACE_MODE_WRITE, d_tracer,
-			  tr, &snapshot_fops);
+	} else {
+		trace_create_file("snapshot", TRACE_MODE_WRITE, d_tracer,
+				  tr, &snapshot_fops);
 #endif
+	}
 
 	trace_create_file("error_log", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_err_log_fops);
@@ -10292,6 +10507,7 @@ __init static void enable_instances(void)
 {
 	struct trace_array *tr;
 	char *curr_str;
+	char *name;
 	char *str;
 	char *tok;
 
@@ -10300,19 +10516,107 @@ __init static void enable_instances(void)
 	str = boot_instance_info;
 
 	while ((curr_str = strsep(&str, "\t"))) {
+		phys_addr_t start = 0;
+		phys_addr_t size = 0;
+		unsigned long addr = 0;
+		bool traceprintk = false;
+		bool traceoff = false;
+		char *flag_delim;
+		char *addr_delim;
 
 		tok = strsep(&curr_str, ",");
 
-		if (IS_ENABLED(CONFIG_TRACER_MAX_TRACE))
-			do_allocate_snapshot(tok);
+		flag_delim = strchr(tok, '^');
+		addr_delim = strchr(tok, '@');
 
-		tr = trace_array_get_by_name(tok, NULL);
-		if (!tr) {
-			pr_warn("Failed to create instance buffer %s\n", curr_str);
+		if (addr_delim)
+			*addr_delim++ = '\0';
+
+		if (flag_delim)
+			*flag_delim++ = '\0';
+
+		name = tok;
+
+		if (flag_delim) {
+			char *flag;
+
+			while ((flag = strsep(&flag_delim, "^"))) {
+				if (strcmp(flag, "traceoff") == 0) {
+					traceoff = true;
+				} else if ((strcmp(flag, "printk") == 0) ||
+					   (strcmp(flag, "traceprintk") == 0) ||
+					   (strcmp(flag, "trace_printk") == 0)) {
+					traceprintk = true;
+				} else {
+					pr_info("Tracing: Invalid instance flag '%s' for %s\n",
+						flag, name);
+				}
+			}
+		}
+
+		tok = addr_delim;
+		if (tok && isdigit(*tok)) {
+			start = memparse(tok, &tok);
+			if (!start) {
+				pr_warn("Tracing: Invalid boot instance address for %s\n",
+					name);
+				continue;
+			}
+			if (*tok != ':') {
+				pr_warn("Tracing: No size specified for instance %s\n", name);
+				continue;
+			}
+			tok++;
+			size = memparse(tok, &tok);
+			if (!size) {
+				pr_warn("Tracing: Invalid boot instance size for %s\n",
+					name);
+				continue;
+			}
+		} else if (tok) {
+			if (!reserve_mem_find_by_name(tok, &start, &size)) {
+				start = 0;
+				pr_warn("Failed to map boot instance %s to %s\n", name, tok);
+				continue;
+			}
+		}
+
+		if (start) {
+			addr = map_pages(start, size);
+			if (addr) {
+				pr_info("Tracing: mapped boot instance %s at physical memory %pa of size 0x%lx\n",
+					name, &start, (unsigned long)size);
+			} else {
+				pr_warn("Tracing: Failed to map boot instance %s\n", name);
+				continue;
+			}
+		} else {
+			/* Only non mapped buffers have snapshot buffers */
+			if (IS_ENABLED(CONFIG_TRACER_MAX_TRACE))
+				do_allocate_snapshot(name);
+		}
+
+		tr = trace_array_create_systems(name, NULL, addr, size);
+		if (IS_ERR(tr)) {
+			pr_warn("Tracing: Failed to create instance buffer %s\n", curr_str);
 			continue;
 		}
-		/* Allow user space to delete it */
-		trace_array_put(tr);
+
+		if (traceoff)
+			tracer_tracing_off(tr);
+
+		if (traceprintk)
+			update_printk_trace(tr);
+
+		/*
+		 * If start is set, then this is a mapped buffer, and
+		 * cannot be deleted by user space, so keep the reference
+		 * to it.
+		 */
+		if (start)
+			tr->flags |= TRACE_ARRAY_FL_BOOT;
+		else
+			trace_array_put(tr);
 
 		while ((tok = strsep(&curr_str, ","))) {
 			early_enable_events(tr, tok, true);