perf: Do the big rename: Performance Counters -> Performance Events

Bye-bye Performance Counters, welcome Performance Events!

In the past few months the perfcounters subsystem has grown out its
initial role of counting hardware events, and has become (and is
becoming) a much broader generic event enumeration, reporting, logging,
monitoring, analysis facility.

Naming its core object 'perf_counter' and naming the subsystem
'perfcounters' has become more and more of a misnomer. With pending
code like hw-breakpoints support the 'counter' name is less and
less appropriate.

All in one, we've decided to rename the subsystem to 'performance
events' and to propagate this rename through all fields, variables
and API names. (in an ABI compatible fashion)

The word 'event' is also a bit shorter than 'counter' - which makes
it slightly more convenient to write/handle as well.

Thanks goes to Stephane Eranian who first observed this misnomer and
suggested a rename.

User-space tooling and ABI compatibility is not affected - this patch
should be function-invariant. (Also, defconfigs were not touched to
keep the size down.)

This patch has been generated via the following script:

  FILES=$(find * -type f | grep -vE 'oprofile|[^K]config')

  sed -i \
    -e 's/PERF_EVENT_/PERF_RECORD_/g' \
    -e 's/PERF_COUNTER/PERF_EVENT/g' \
    -e 's/perf_counter/perf_event/g' \
    -e 's/nb_counters/nb_events/g' \
    -e 's/swcounter/swevent/g' \
    -e 's/tpcounter_event/tp_event/g' \
    $FILES

  for N in $(find . -name perf_counter.[ch]); do
    M=$(echo $N | sed 's/perf_counter/perf_event/g')
    mv $N $M
  done

  FILES=$(find . -name perf_event.*)

  sed -i \
    -e 's/COUNTER_MASK/REG_MASK/g' \
    -e 's/COUNTER/EVENT/g' \
    -e 's/\<event\>/event_id/g' \
    -e 's/counter/event/g' \
    -e 's/Counter/Event/g' \
    $FILES

... to keep it as correct as possible. This script can also be
used by anyone who has pending perfcounters patches - it converts
a Linux kernel tree over to the new naming. We tried to time this
change to the point in time where the amount of pending patches
is the smallest: the end of the merge window.

Namespace clashes were fixed up in a preparatory patch - and some
stylistic fallout will be fixed up in a subsequent patch.

( NOTE: 'counters' are still the proper terminology when we deal
  with hardware registers - and these sed scripts are a bit
  over-eager in renaming them. I've undone some of that, but
  in case there's something left where 'counter' would be
  better than 'event' we can undo that on an individual basis
  instead of touching an otherwise nicely automated patch. )

Suggested-by: Stephane Eranian <eranian@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Paul Mackerras <paulus@samba.org>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 556 insertions, 0 deletions

diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
new file mode 100644
index 000000000000..2d6a1b10c81d
--- /dev/null
+++ b/arch/sparc/kernel/perf_event.c
@@ -0,0 +1,556 @@
+/* Performance event support for sparc64.
+ *
+ * Copyright (C) 2009 David S. Miller <davem@davemloft.net>
+ *
+ * This code is based almost entirely upon the x86 perf event
+ * code, which is:
+ *
+ *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
+ *  Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
+ *  Copyright (C) 2009 Jaswinder Singh Rajput
+ *  Copyright (C) 2009 Advanced Micro Devices, Inc., Robert Richter
+ *  Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ */
+
+#include <linux/perf_event.h>
+#include <linux/kprobes.h>
+#include <linux/kernel.h>
+#include <linux/kdebug.h>
+#include <linux/mutex.h>
+
+#include <asm/cpudata.h>
+#include <asm/atomic.h>
+#include <asm/nmi.h>
+#include <asm/pcr.h>
+
+/* Sparc64 chips have two performance counters, 32-bits each, with
+ * overflow interrupts generated on transition from 0xffffffff to 0.
+ * The counters are accessed in one go using a 64-bit register.
+ *
+ * Both counters are controlled using a single control register.  The
+ * only way to stop all sampling is to clear all of the context (user,
+ * supervisor, hypervisor) sampling enable bits.  But these bits apply
+ * to both counters, thus the two counters can't be enabled/disabled
+ * individually.
+ *
+ * The control register has two event fields, one for each of the two
+ * counters.  It's thus nearly impossible to have one counter going
+ * while keeping the other one stopped.  Therefore it is possible to
+ * get overflow interrupts for counters not currently "in use" and
+ * that condition must be checked in the overflow interrupt handler.
+ *
+ * So we use a hack, in that we program inactive counters with the
+ * "sw_count0" and "sw_count1" events.  These count how many times
+ * the instruction "sethi %hi(0xfc000), %g0" is executed.  It's an
+ * unusual way to encode a NOP and therefore will not trigger in
+ * normal code.
+ */
+
+#define MAX_HWEVENTS			2
+#define MAX_PERIOD			((1UL << 32) - 1)
+
+#define PIC_UPPER_INDEX			0
+#define PIC_LOWER_INDEX			1
+
+struct cpu_hw_events {
+	struct perf_event	*events[MAX_HWEVENTS];
+	unsigned long		used_mask[BITS_TO_LONGS(MAX_HWEVENTS)];
+	unsigned long		active_mask[BITS_TO_LONGS(MAX_HWEVENTS)];
+	int enabled;
+};
+DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = { .enabled = 1, };
+
+struct perf_event_map {
+	u16	encoding;
+	u8	pic_mask;
+#define PIC_NONE	0x00
+#define PIC_UPPER	0x01
+#define PIC_LOWER	0x02
+};
+
+struct sparc_pmu {
+	const struct perf_event_map	*(*event_map)(int);
+	int				max_events;
+	int				upper_shift;
+	int				lower_shift;
+	int				event_mask;
+	int				hv_bit;
+	int				irq_bit;
+	int				upper_nop;
+	int				lower_nop;
+};
+
+static const struct perf_event_map ultra3i_perfmon_event_map[] = {
+	[PERF_COUNT_HW_CPU_CYCLES] = { 0x0000, PIC_UPPER | PIC_LOWER },
+	[PERF_COUNT_HW_INSTRUCTIONS] = { 0x0001, PIC_UPPER | PIC_LOWER },
+	[PERF_COUNT_HW_CACHE_REFERENCES] = { 0x0009, PIC_LOWER },
+	[PERF_COUNT_HW_CACHE_MISSES] = { 0x0009, PIC_UPPER },
+};
+
+static const struct perf_event_map *ultra3i_event_map(int event_id)
+{
+	return &ultra3i_perfmon_event_map[event_id];
+}
+
+static const struct sparc_pmu ultra3i_pmu = {
+	.event_map	= ultra3i_event_map,
+	.max_events	= ARRAY_SIZE(ultra3i_perfmon_event_map),
+	.upper_shift	= 11,
+	.lower_shift	= 4,
+	.event_mask	= 0x3f,
+	.upper_nop	= 0x1c,
+	.lower_nop	= 0x14,
+};
+
+static const struct perf_event_map niagara2_perfmon_event_map[] = {
+	[PERF_COUNT_HW_CPU_CYCLES] = { 0x02ff, PIC_UPPER | PIC_LOWER },
+	[PERF_COUNT_HW_INSTRUCTIONS] = { 0x02ff, PIC_UPPER | PIC_LOWER },
+	[PERF_COUNT_HW_CACHE_REFERENCES] = { 0x0208, PIC_UPPER | PIC_LOWER },
+	[PERF_COUNT_HW_CACHE_MISSES] = { 0x0302, PIC_UPPER | PIC_LOWER },
+	[PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = { 0x0201, PIC_UPPER | PIC_LOWER },
+	[PERF_COUNT_HW_BRANCH_MISSES] = { 0x0202, PIC_UPPER | PIC_LOWER },
+};
+
+static const struct perf_event_map *niagara2_event_map(int event_id)
+{
+	return &niagara2_perfmon_event_map[event_id];
+}
+
+static const struct sparc_pmu niagara2_pmu = {
+	.event_map	= niagara2_event_map,
+	.max_events	= ARRAY_SIZE(niagara2_perfmon_event_map),
+	.upper_shift	= 19,
+	.lower_shift	= 6,
+	.event_mask	= 0xfff,
+	.hv_bit		= 0x8,
+	.irq_bit	= 0x03,
+	.upper_nop	= 0x220,
+	.lower_nop	= 0x220,
+};
+
+static const struct sparc_pmu *sparc_pmu __read_mostly;
+
+static u64 event_encoding(u64 event_id, int idx)
+{
+	if (idx == PIC_UPPER_INDEX)
+		event_id <<= sparc_pmu->upper_shift;
+	else
+		event_id <<= sparc_pmu->lower_shift;
+	return event_id;
+}
+
+static u64 mask_for_index(int idx)
+{
+	return event_encoding(sparc_pmu->event_mask, idx);
+}
+
+static u64 nop_for_index(int idx)
+{
+	return event_encoding(idx == PIC_UPPER_INDEX ?
+			      sparc_pmu->upper_nop :
+			      sparc_pmu->lower_nop, idx);
+}
+
+static inline void sparc_pmu_enable_event(struct hw_perf_event *hwc,
+					    int idx)
+{
+	u64 val, mask = mask_for_index(idx);
+
+	val = pcr_ops->read();
+	pcr_ops->write((val & ~mask) | hwc->config);
+}
+
+static inline void sparc_pmu_disable_event(struct hw_perf_event *hwc,
+					     int idx)
+{
+	u64 mask = mask_for_index(idx);
+	u64 nop = nop_for_index(idx);
+	u64 val = pcr_ops->read();
+
+	pcr_ops->write((val & ~mask) | nop);
+}
+
+void hw_perf_enable(void)
+{
+	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+	u64 val;
+	int i;
+
+	if (cpuc->enabled)
+		return;
+
+	cpuc->enabled = 1;
+	barrier();
+
+	val = pcr_ops->read();
+
+	for (i = 0; i < MAX_HWEVENTS; i++) {
+		struct perf_event *cp = cpuc->events[i];
+		struct hw_perf_event *hwc;
+
+		if (!cp)
+			continue;
+		hwc = &cp->hw;
+		val |= hwc->config_base;
+	}
+
+	pcr_ops->write(val);
+}
+
+void hw_perf_disable(void)
+{
+	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+	u64 val;
+
+	if (!cpuc->enabled)
+		return;
+
+	cpuc->enabled = 0;
+
+	val = pcr_ops->read();
+	val &= ~(PCR_UTRACE | PCR_STRACE |
+		 sparc_pmu->hv_bit | sparc_pmu->irq_bit);
+	pcr_ops->write(val);
+}
+
+static u32 read_pmc(int idx)
+{
+	u64 val;
+
+	read_pic(val);
+	if (idx == PIC_UPPER_INDEX)
+		val >>= 32;
+
+	return val & 0xffffffff;
+}
+
+static void write_pmc(int idx, u64 val)
+{
+	u64 shift, mask, pic;
+
+	shift = 0;
+	if (idx == PIC_UPPER_INDEX)
+		shift = 32;
+
+	mask = ((u64) 0xffffffff) << shift;
+	val <<= shift;
+
+	read_pic(pic);
+	pic &= ~mask;
+	pic |= val;
+	write_pic(pic);
+}
+
+static int sparc_perf_event_set_period(struct perf_event *event,
+					 struct hw_perf_event *hwc, int idx)
+{
+	s64 left = atomic64_read(&hwc->period_left);
+	s64 period = hwc->sample_period;
+	int ret = 0;
+
+	if (unlikely(left <= -period)) {
+		left = period;
+		atomic64_set(&hwc->period_left, left);
+		hwc->last_period = period;
+		ret = 1;
+	}
+
+	if (unlikely(left <= 0)) {
+		left += period;
+		atomic64_set(&hwc->period_left, left);
+		hwc->last_period = period;
+		ret = 1;
+	}
+	if (left > MAX_PERIOD)
+		left = MAX_PERIOD;
+
+	atomic64_set(&hwc->prev_count, (u64)-left);
+
+	write_pmc(idx, (u64)(-left) & 0xffffffff);
+
+	perf_event_update_userpage(event);
+
+	return ret;
+}
+
+static int sparc_pmu_enable(struct perf_event *event)
+{
+	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+	struct hw_perf_event *hwc = &event->hw;
+	int idx = hwc->idx;
+
+	if (test_and_set_bit(idx, cpuc->used_mask))
+		return -EAGAIN;
+
+	sparc_pmu_disable_event(hwc, idx);
+
+	cpuc->events[idx] = event;
+	set_bit(idx, cpuc->active_mask);
+
+	sparc_perf_event_set_period(event, hwc, idx);
+	sparc_pmu_enable_event(hwc, idx);
+	perf_event_update_userpage(event);
+	return 0;
+}
+
+static u64 sparc_perf_event_update(struct perf_event *event,
+				     struct hw_perf_event *hwc, int idx)
+{
+	int shift = 64 - 32;
+	u64 prev_raw_count, new_raw_count;
+	s64 delta;
+
+again:
+	prev_raw_count = atomic64_read(&hwc->prev_count);
+	new_raw_count = read_pmc(idx);
+
+	if (atomic64_cmpxchg(&hwc->prev_count, prev_raw_count,
+			     new_raw_count) != prev_raw_count)
+		goto again;
+
+	delta = (new_raw_count << shift) - (prev_raw_count << shift);
+	delta >>= shift;
+
+	atomic64_add(delta, &event->count);
+	atomic64_sub(delta, &hwc->period_left);
+
+	return new_raw_count;
+}
+
+static void sparc_pmu_disable(struct perf_event *event)
+{
+	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+	struct hw_perf_event *hwc = &event->hw;
+	int idx = hwc->idx;
+
+	clear_bit(idx, cpuc->active_mask);
+	sparc_pmu_disable_event(hwc, idx);
+
+	barrier();
+
+	sparc_perf_event_update(event, hwc, idx);
+	cpuc->events[idx] = NULL;
+	clear_bit(idx, cpuc->used_mask);
+
+	perf_event_update_userpage(event);
+}
+
+static void sparc_pmu_read(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	sparc_perf_event_update(event, hwc, hwc->idx);
+}
+
+static void sparc_pmu_unthrottle(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	sparc_pmu_enable_event(hwc, hwc->idx);
+}
+
+static atomic_t active_events = ATOMIC_INIT(0);
+static DEFINE_MUTEX(pmc_grab_mutex);
+
+void perf_event_grab_pmc(void)
+{
+	if (atomic_inc_not_zero(&active_events))
+		return;
+
+	mutex_lock(&pmc_grab_mutex);
+	if (atomic_read(&active_events) == 0) {
+		if (atomic_read(&nmi_active) > 0) {
+			on_each_cpu(stop_nmi_watchdog, NULL, 1);
+			BUG_ON(atomic_read(&nmi_active) != 0);
+		}
+		atomic_inc(&active_events);
+	}
+	mutex_unlock(&pmc_grab_mutex);
+}
+
+void perf_event_release_pmc(void)
+{
+	if (atomic_dec_and_mutex_lock(&active_events, &pmc_grab_mutex)) {
+		if (atomic_read(&nmi_active) == 0)
+			on_each_cpu(start_nmi_watchdog, NULL, 1);
+		mutex_unlock(&pmc_grab_mutex);
+	}
+}
+
+static void hw_perf_event_destroy(struct perf_event *event)
+{
+	perf_event_release_pmc();
+}
+
+static int __hw_perf_event_init(struct perf_event *event)
+{
+	struct perf_event_attr *attr = &event->attr;
+	struct hw_perf_event *hwc = &event->hw;
+	const struct perf_event_map *pmap;
+	u64 enc;
+
+	if (atomic_read(&nmi_active) < 0)
+		return -ENODEV;
+
+	if (attr->type != PERF_TYPE_HARDWARE)
+		return -EOPNOTSUPP;
+
+	if (attr->config >= sparc_pmu->max_events)
+		return -EINVAL;
+
+	perf_event_grab_pmc();
+	event->destroy = hw_perf_event_destroy;
+
+	/* We save the enable bits in the config_base.  So to
+	 * turn off sampling just write 'config', and to enable
+	 * things write 'config | config_base'.
+	 */
+	hwc->config_base = sparc_pmu->irq_bit;
+	if (!attr->exclude_user)
+		hwc->config_base |= PCR_UTRACE;
+	if (!attr->exclude_kernel)
+		hwc->config_base |= PCR_STRACE;
+	if (!attr->exclude_hv)
+		hwc->config_base |= sparc_pmu->hv_bit;
+
+	if (!hwc->sample_period) {
+		hwc->sample_period = MAX_PERIOD;
+		hwc->last_period = hwc->sample_period;
+		atomic64_set(&hwc->period_left, hwc->sample_period);
+	}
+
+	pmap = sparc_pmu->event_map(attr->config);
+
+	enc = pmap->encoding;
+	if (pmap->pic_mask & PIC_UPPER) {
+		hwc->idx = PIC_UPPER_INDEX;
+		enc <<= sparc_pmu->upper_shift;
+	} else {
+		hwc->idx = PIC_LOWER_INDEX;
+		enc <<= sparc_pmu->lower_shift;
+	}
+
+	hwc->config |= enc;
+	return 0;
+}
+
+static const struct pmu pmu = {
+	.enable		= sparc_pmu_enable,
+	.disable	= sparc_pmu_disable,
+	.read		= sparc_pmu_read,
+	.unthrottle	= sparc_pmu_unthrottle,
+};
+
+const struct pmu *hw_perf_event_init(struct perf_event *event)
+{
+	int err = __hw_perf_event_init(event);
+
+	if (err)
+		return ERR_PTR(err);
+	return &pmu;
+}
+
+void perf_event_print_debug(void)
+{
+	unsigned long flags;
+	u64 pcr, pic;
+	int cpu;
+
+	if (!sparc_pmu)
+		return;
+
+	local_irq_save(flags);
+
+	cpu = smp_processor_id();
+
+	pcr = pcr_ops->read();
+	read_pic(pic);
+
+	pr_info("\n");
+	pr_info("CPU#%d: PCR[%016llx] PIC[%016llx]\n",
+		cpu, pcr, pic);
+
+	local_irq_restore(flags);
+}
+
+static int __kprobes perf_event_nmi_handler(struct notifier_block *self,
+					      unsigned long cmd, void *__args)
+{
+	struct die_args *args = __args;
+	struct perf_sample_data data;
+	struct cpu_hw_events *cpuc;
+	struct pt_regs *regs;
+	int idx;
+
+	if (!atomic_read(&active_events))
+		return NOTIFY_DONE;
+
+	switch (cmd) {
+	case DIE_NMI:
+		break;
+
+	default:
+		return NOTIFY_DONE;
+	}
+
+	regs = args->regs;
+
+	data.addr = 0;
+
+	cpuc = &__get_cpu_var(cpu_hw_events);
+	for (idx = 0; idx < MAX_HWEVENTS; idx++) {
+		struct perf_event *event = cpuc->events[idx];
+		struct hw_perf_event *hwc;
+		u64 val;
+
+		if (!test_bit(idx, cpuc->active_mask))
+			continue;
+		hwc = &event->hw;
+		val = sparc_perf_event_update(event, hwc, idx);
+		if (val & (1ULL << 31))
+			continue;
+
+		data.period = event->hw.last_period;
+		if (!sparc_perf_event_set_period(event, hwc, idx))
+			continue;
+
+		if (perf_event_overflow(event, 1, &data, regs))
+			sparc_pmu_disable_event(hwc, idx);
+	}
+
+	return NOTIFY_STOP;
+}
+
+static __read_mostly struct notifier_block perf_event_nmi_notifier = {
+	.notifier_call		= perf_event_nmi_handler,
+};
+
+static bool __init supported_pmu(void)
+{
+	if (!strcmp(sparc_pmu_type, "ultra3i")) {
+		sparc_pmu = &ultra3i_pmu;
+		return true;
+	}
+	if (!strcmp(sparc_pmu_type, "niagara2")) {
+		sparc_pmu = &niagara2_pmu;
+		return true;
+	}
+	return false;
+}
+
+void __init init_hw_perf_events(void)
+{
+	pr_info("Performance events: ");
+
+	if (!supported_pmu()) {
+		pr_cont("No support for PMU type '%s'\n", sparc_pmu_type);
+		return;
+	}
+
+	pr_cont("Supported PMU type is '%s'\n", sparc_pmu_type);
+
+	/* All sparc64 PMUs currently have 2 events.  But this simple
+	 * driver only supports one active event at a time.
+	 */
+	perf_max_events = 1;
+
+	register_die_notifier(&perf_event_nmi_notifier);
+}