[PATCH 5/5] arm/perfevents: implement perf event support for ARMv6
Jamie Iles
jamie.iles at picochip.com
Mon Dec 14 09:04:41 EST 2009
This patch implements support for ARMv6 performance counters in the
Linux performance events subsystem. ARMv6 architectures that have the
performance counters should enable HW_PERF_EVENTS and define the
interrupts for the counters in arch/arm/kernel/perf_event.c
Signed-off-by: Jamie Iles <jamie.iles at picochip.com>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Ingo Molnar <mingo at elte.hu>
---
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/perf_event.c | 1034 ++++++++++++++++++++++++++++++++++++++++++
arch/arm/mm/Kconfig | 8 +
3 files changed, 1043 insertions(+), 0 deletions(-)
create mode 100644 arch/arm/kernel/perf_event.c
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 286a276..44ebf36 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -47,6 +47,7 @@ obj-$(CONFIG_CPU_XSC3) += xscale-cp0.o
obj-$(CONFIG_CPU_MOHAWK) += xscale-cp0.o
obj-$(CONFIG_IWMMXT) += iwmmxt.o
obj-$(CONFIG_CPU_HAS_PMU) += pmu.o
+obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o
AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt
ifneq ($(CONFIG_ARCH_EBSA110),y)
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
new file mode 100644
index 0000000..358fd31
--- /dev/null
+++ b/arch/arm/kernel/perf_event.c
@@ -0,0 +1,1034 @@
+#undef DEBUG
+
+/*
+ * ARMv6 performance counter support.
+ *
+ * Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
+ *
+ * This code is based on the sparc64 perf event code, which is in turn based
+ * on the x86 code. Callchain code is based on the ARM OProfile backtrace
+ * code.
+ */
+#define pr_fmt(fmt) "armv6_perfctr: " fmt
+
+#include <linux/kernel.h>
+#include <linux/perf_event.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+
+#include <asm/irq_regs.h>
+#include <asm/stacktrace.h>
+#include <asm/irq.h>
+#include <asm/pmu.h>
+
+/*
+ * ARMv6 has 2 configurable performance counters and a single cycle counter.
+ * They all share a single reset bit but can be written to zero so we can use
+ * that for a reset.
+ *
+ * The counters can't be individually enabled or disabled so when we remove
+ * one event and replace it with another we could get spurious counts from the
+ * wrong event. However, we can take advantage of the fact that the
+ * performance counters can export events to the event bus, and the event bus
+ * itself can be monitored. This requires that we *don't* export the events to
+ * the event bus. The procedure for disabling a configurable counter is:
+ * - change the counter to count the ETMEXTOUT[0] signal (0x20). This
+ * effectively stops the counter from counting.
+ * - disable the counter's interrupt generation (each counter has it's
+ * own interrupt enable bit).
+ * Once stopped, the counter value can be written as 0 to reset.
+ *
+ * To enable a counter:
+ * - enable the counter's interrupt generation.
+ * - set the new event type.
+ *
+ * Note: the dedicated cycle counter only counts cycles and can't be
+ * enabled/disabled independently of the others. When we want to disable the
+ * cycle counter, we have to just disable the interrupt reporting and start
+ * ignoring that counter. When re-enabling, we have to reset the value and
+ * enable the interrupt.
+ */
+
+static const struct pmu_irqs *pmu_irqs;
+
+/*
+ * Hardware lock to serialize accesses to PMU registers. Needed for the
+ * read/modify/write sequences.
+ */
+DEFINE_SPINLOCK(pmu_lock);
+
+enum arm_perf_types {
+ ARM_PERFCTR_ICACHE_MISS = 0x0,
+ ARM_PERFCTR_IBUF_STALL = 0x1,
+ ARM_PERFCTR_DDEP_STALL = 0x2,
+ ARM_PERFCTR_ITLB_MISS = 0x3,
+ ARM_PERFCTR_DTLB_MISS = 0x4,
+ ARM_PERFCTR_BR_EXEC = 0x5,
+ ARM_PERFCTR_BR_MISPREDICT = 0x6,
+ ARM_PERFCTR_INSTR_EXEC = 0x7,
+ ARM_PERFCTR_DCACHE_HIT = 0x9,
+ ARM_PERFCTR_DCACHE_ACCESS = 0xA,
+ ARM_PERFCTR_DCACHE_MISS = 0xB,
+ ARM_PERFCTR_DCACHE_WBACK = 0xC,
+ ARM_PERFCTR_SW_PC_CHANGE = 0xD,
+ ARM_PERFCTR_MAIN_TLB_MISS = 0xF,
+ ARM_PERFCTR_EXPL_D_ACCESS = 0x10,
+ ARM_PERFCTR_LSU_FULL_STALL = 0x11,
+ ARM_PERFCTR_WBUF_DRAINED = 0x12,
+ ARM_PERFCTR_CPU_CYCLES = 0xFF,
+ ARM_PERFCTR_NOP = 0x20,
+};
+
+/* We support using the full 32 bits of each counter. */
+#define MAX_PERIOD ((1LLU << 32) - 1)
+
+enum armv6_counters {
+ ARMV6_CYCLE_COUNTER = 1,
+ ARMV6_COUNTER0,
+ ARMV6_COUNTER1,
+};
+
+/* We support 3 simultaneous events, but they begin from 1. */
+#define ARMV6_MAX_HWEVENTS 4
+
+/* The events for a given CPU. */
+struct cpu_hw_events {
+ /*
+ * The events that are active on the CPU for the given index. Index 0
+ * is reserved.
+ */
+ struct perf_event *events[ARMV6_MAX_HWEVENTS];
+
+ /*
+ * A 1 bit for an index indicates that the counter is being used for
+ * an event. A 0 means that the counter can be used.
+ */
+ unsigned long used_mask[BITS_TO_LONGS(ARMV6_MAX_HWEVENTS)];
+
+ /*
+ * A 1 bit for an index indicates that the counter is actively being
+ * used.
+ */
+ unsigned long active_mask[BITS_TO_LONGS(ARMV6_MAX_HWEVENTS)];
+};
+DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);
+
+#define HW_OP_UNSUPPORTED 0xFFFF
+
+/*
+ * The hardware events that we support. We do support cache operations but
+ * we have harvard caches and no way to combine instruction and data
+ * accesses/misses in hardware.
+ */
+static const unsigned v6_perf_map[PERF_COUNT_HW_MAX] = {
+ [PERF_COUNT_HW_CPU_CYCLES] = ARM_PERFCTR_CPU_CYCLES,
+ [PERF_COUNT_HW_INSTRUCTIONS] = ARM_PERFCTR_INSTR_EXEC,
+ [PERF_COUNT_HW_CACHE_REFERENCES] = HW_OP_UNSUPPORTED,
+ [PERF_COUNT_HW_CACHE_MISSES] = HW_OP_UNSUPPORTED,
+ [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = ARM_PERFCTR_BR_EXEC,
+ [PERF_COUNT_HW_BRANCH_MISSES] = ARM_PERFCTR_BR_MISPREDICT,
+ [PERF_COUNT_HW_BUS_CYCLES] = HW_OP_UNSUPPORTED,
+};
+
+static inline int
+armv6_map_hw_event(u64 config)
+{
+ int mapping = v6_perf_map[config];
+ if (HW_OP_UNSUPPORTED == mapping)
+ mapping = -EOPNOTSUPP;
+ return mapping;
+}
+
+#define C(_x) \
+ PERF_COUNT_HW_CACHE_##_x
+
+#define CACHE_OP_UNSUPPORTED 0xFFFF
+
+static const unsigned v6_perf_cache_map[PERF_COUNT_HW_CACHE_MAX]
+ [PERF_COUNT_HW_CACHE_OP_MAX]
+ [PERF_COUNT_HW_CACHE_RESULT_MAX] = {
+ [C(L1D)] = {
+ /*
+ * The performance counters don't differentiate between read
+ * and write accesses/misses so this isn't strictly correct,
+ * but it's the best we can do. Writes and reads get
+ * combined.
+ */
+ [C(OP_READ)] = {
+ [C(RESULT_ACCESS)] = ARM_PERFCTR_DCACHE_ACCESS,
+ [C(RESULT_MISS)] = ARM_PERFCTR_DCACHE_MISS,
+ },
+ [C(OP_WRITE)] = {
+ [C(RESULT_ACCESS)] = ARM_PERFCTR_DCACHE_ACCESS,
+ [C(RESULT_MISS)] = ARM_PERFCTR_DCACHE_MISS,
+ },
+ [C(OP_PREFETCH)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = CACHE_OP_UNSUPPORTED,
+ },
+ },
+ [C(L1I)] = {
+ [C(OP_READ)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = ARM_PERFCTR_ICACHE_MISS,
+ },
+ [C(OP_WRITE)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = ARM_PERFCTR_ICACHE_MISS,
+ },
+ [C(OP_PREFETCH)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = CACHE_OP_UNSUPPORTED,
+ },
+ },
+ [C(LL)] = {
+ [C(OP_READ)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = CACHE_OP_UNSUPPORTED,
+ },
+ [C(OP_WRITE)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = CACHE_OP_UNSUPPORTED,
+ },
+ [C(OP_PREFETCH)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = CACHE_OP_UNSUPPORTED,
+ },
+ },
+ [C(DTLB)] = {
+ /*
+ * The ARM performance counters can count micro DTLB misses,
+ * micro ITLB misses and main TLB misses. There isn't an event
+ * for TLB misses, so use the micro misses here and if users
+ * want the main TLB misses they can use a raw counter.
+ */
+ [C(OP_READ)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = ARM_PERFCTR_DTLB_MISS,
+ },
+ [C(OP_WRITE)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = ARM_PERFCTR_DTLB_MISS,
+ },
+ [C(OP_PREFETCH)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = CACHE_OP_UNSUPPORTED,
+ },
+ },
+ [C(ITLB)] = {
+ [C(OP_READ)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = ARM_PERFCTR_ITLB_MISS,
+ },
+ [C(OP_WRITE)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = ARM_PERFCTR_ITLB_MISS,
+ },
+ [C(OP_PREFETCH)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = CACHE_OP_UNSUPPORTED,
+ },
+ },
+ [C(BPU)] = {
+ [C(OP_READ)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = CACHE_OP_UNSUPPORTED,
+ },
+ [C(OP_WRITE)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = CACHE_OP_UNSUPPORTED,
+ },
+ [C(OP_PREFETCH)] = {
+ [C(RESULT_ACCESS)] = CACHE_OP_UNSUPPORTED,
+ [C(RESULT_MISS)] = CACHE_OP_UNSUPPORTED,
+ },
+ },
+};
+
+static const int
+armv6_map_cache_event(u64 config)
+{
+ unsigned int cache_type, cache_op, cache_result, ret;
+
+ cache_type = (config >> 0) & 0xff;
+ if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
+ return -EINVAL;
+
+ cache_op = (config >> 8) & 0xff;
+ if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
+ return -EINVAL;
+
+ cache_result = (config >> 16) & 0xff;
+ if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
+ return -EINVAL;
+
+ ret = (int)v6_perf_cache_map[cache_type][cache_op][cache_result];
+
+ if (ret == CACHE_OP_UNSUPPORTED)
+ return -ENOENT;
+
+ return ret;
+}
+
+#define PMCR_ENABLE (1 << 0)
+#define PMCR_CTR01_RESET (1 << 1)
+#define PMCR_CCOUNT_RESET (1 << 2)
+#define PMCR_CCOUNT_DIV (1 << 3)
+#define PMCR_COUNT0_IEN (1 << 4)
+#define PMCR_COUNT1_IEN (1 << 5)
+#define PMCR_CCOUNT_IEN (1 << 6)
+#define PMCR_COUNT0_OVERFLOW (1 << 8)
+#define PMCR_COUNT1_OVERFLOW (1 << 9)
+#define PMCR_CCOUNT_OVERFLOW (1 << 10)
+#define PMCR_EVT_COUNT0_SHIFT 20
+#define PMCR_EVT_COUNT0_MASK (0xFF << PMCR_EVT_COUNT0_SHIFT)
+#define PMCR_EVT_COUNT1_SHIFT 12
+#define PMCR_EVT_COUNT1_MASK (0xFF << PMCR_EVT_COUNT1_SHIFT)
+
+static inline unsigned long
+pmcr_read(void)
+{
+ u32 val;
+ asm volatile("mrc p15, 0, %0, c15, c12, 0" : "=r"(val));
+ return val;
+}
+
+static inline void
+pmcr_write(unsigned long val)
+{
+ asm volatile("mcr p15, 0, %0, c15, c12, 0" : : "r"(val));
+}
+
+#define PMCR_OVERFLOWED_MASK \
+ (PMCR_COUNT0_OVERFLOW | PMCR_COUNT1_OVERFLOW | PMCR_CCOUNT_OVERFLOW)
+
+static inline int
+pmcr_has_overflowed(unsigned long pmcr)
+{
+ return (pmcr & PMCR_OVERFLOWED_MASK);
+}
+
+static inline int
+pmcr_counter_has_overflowed(unsigned long pmcr,
+ enum armv6_counters counter)
+{
+ int ret;
+
+ if (ARMV6_CYCLE_COUNTER == counter)
+ ret = pmcr & PMCR_CCOUNT_OVERFLOW;
+ else if (ARMV6_COUNTER0 == counter)
+ ret = pmcr & PMCR_COUNT0_OVERFLOW;
+ else if (ARMV6_COUNTER1 == counter)
+ ret = pmcr & PMCR_COUNT1_OVERFLOW;
+ else
+ BUG();
+
+ return ret;
+}
+
+static inline unsigned long
+armv6pmu_read_counter(enum armv6_counters counter)
+{
+ unsigned long value;
+
+ if (ARMV6_CYCLE_COUNTER == counter)
+ asm volatile("mrc p15, 0, %0, c15, c12, 1" : "=r"(value));
+ else if (ARMV6_COUNTER0 == counter)
+ asm volatile("mrc p15, 0, %0, c15, c12, 2" : "=r"(value));
+ else if (ARMV6_COUNTER1 == counter)
+ asm volatile("mrc p15, 0, %0, c15, c12, 3" : "=r"(value));
+ else
+ BUG();
+
+ return value;
+}
+
+static inline void
+armv6pmu_write_counter(enum armv6_counters counter,
+ unsigned long value)
+{
+ if (ARMV6_CYCLE_COUNTER == counter)
+ asm volatile("mcr p15, 0, %0, c15, c12, 1" : : "r"(value));
+ else if (ARMV6_COUNTER0 == counter)
+ asm volatile("mcr p15, 0, %0, c15, c12, 2" : : "r"(value));
+ else if (ARMV6_COUNTER1 == counter)
+ asm volatile("mcr p15, 0, %0, c15, c12, 3" : : "r"(value));
+ else
+ BUG();
+}
+
+static int
+armv6pmu_place_event(struct cpu_hw_events *cpuc,
+ struct hw_perf_event *event)
+{
+ /* Always place a cycle counter into the cycle counter. */
+ if (ARM_PERFCTR_CPU_CYCLES == event->config_base) {
+ if (test_and_set_bit(ARMV6_CYCLE_COUNTER, cpuc->used_mask))
+ return -EAGAIN;
+
+ return ARMV6_CYCLE_COUNTER;
+ } else {
+ /*
+ * For anything other than a cycle counter, try and use
+ * counter0 and counter1.
+ */
+ if (!test_and_set_bit(ARMV6_COUNTER1, cpuc->used_mask)) {
+ return ARMV6_COUNTER1;
+ }
+
+ if (!test_and_set_bit(ARMV6_COUNTER0, cpuc->used_mask)) {
+ return ARMV6_COUNTER0;
+ }
+
+ /* The counters are all in use. */
+ return -EAGAIN;
+ }
+}
+
+static void
+armv6pmu_disable_event(struct cpu_hw_events *cpuc,
+ struct hw_perf_event *hwc,
+ int idx)
+{
+ unsigned long val, mask, evt, flags;
+
+ if (ARMV6_CYCLE_COUNTER == idx) {
+ mask = PMCR_CCOUNT_IEN;
+ evt = 0;
+ } else if (ARMV6_COUNTER0 == idx) {
+ mask = PMCR_COUNT0_IEN | PMCR_EVT_COUNT0_MASK;
+ evt = ARM_PERFCTR_NOP << PMCR_EVT_COUNT0_SHIFT;
+ } else if (ARMV6_COUNTER1 == idx) {
+ mask = PMCR_COUNT1_IEN | PMCR_EVT_COUNT1_MASK;
+ evt = ARM_PERFCTR_NOP << PMCR_EVT_COUNT1_SHIFT;
+ } else {
+ BUG();
+ }
+
+ /*
+ * Mask out the current event and set the counter to count the number
+ * of ETM bus signal assertion cycles. The external reporting should
+ * be disabled and so this should never increment.
+ */
+ spin_lock_irqsave(&pmu_lock, flags);
+ val = pmcr_read();
+ val &= ~mask;
+ val |= evt;
+ pmcr_write(val);
+ spin_unlock_irqrestore(&pmu_lock, flags);
+}
+
+static void
+armv6pmu_enable_event(struct cpu_hw_events *cpuc,
+ struct hw_perf_event *hwc,
+ int idx)
+{
+ unsigned long val, mask, evt, flags;
+
+ if (ARMV6_CYCLE_COUNTER == idx) {
+ mask = 0;
+ evt = PMCR_CCOUNT_IEN;
+ } else if (ARMV6_COUNTER0 == idx) {
+ mask = PMCR_EVT_COUNT0_MASK;
+ evt = (hwc->config_base << PMCR_EVT_COUNT0_SHIFT) |
+ PMCR_COUNT0_IEN;
+ } else if (ARMV6_COUNTER1 == idx) {
+ mask = PMCR_EVT_COUNT1_MASK;
+ evt = (hwc->config_base << PMCR_EVT_COUNT1_SHIFT) |
+ PMCR_COUNT1_IEN;
+ } else {
+ BUG();
+ }
+
+ /*
+ * Mask out the current event and set the counter to count the event
+ * that we're interested in.
+ */
+ spin_lock_irqsave(&pmu_lock, flags);
+ val = pmcr_read();
+ val &= ~mask;
+ val |= evt;
+ pmcr_write(val);
+ spin_unlock_irqrestore(&pmu_lock, flags);
+}
+
+static int
+armv6pmu_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);
+
+ armv6pmu_write_counter(idx, (u64)(-left) & 0xffffffff);
+
+ perf_event_update_userpage(event);
+
+ return ret;
+}
+
+static int
+armv6pmu_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;
+ int err = 0;
+
+ /* If we don't have a space for the counter then finish early. */
+ idx = armv6pmu_place_event(cpuc, hwc);
+ if (idx < 0) {
+ err = idx;
+ goto out;
+ }
+
+ /*
+ * If there is an event in the counter we are going to use then make
+ * sure it is disabled.
+ */
+ event->hw.idx = idx;
+ armv6pmu_disable_event(cpuc, hwc, idx);
+ cpuc->events[idx] = event;
+ set_bit(idx, cpuc->active_mask);
+
+ /* Set the period for the event. */
+ armv6pmu_event_set_period(event, hwc, idx);
+
+ /* Enable the event. */
+ armv6pmu_enable_event(cpuc, hwc, idx);
+
+ /* Propagate our changes to the userspace mapping. */
+ perf_event_update_userpage(event);
+
+out:
+ return err;
+}
+
+static u64
+armv6pmu_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 = armv6pmu_read_counter(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
+armv6pmu_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;
+
+ WARN_ON(idx < 0);
+
+ clear_bit(idx, cpuc->active_mask);
+ armv6pmu_disable_event(cpuc, hwc, idx);
+
+ barrier();
+
+ armv6pmu_event_update(event, hwc, idx);
+ cpuc->events[idx] = NULL;
+ clear_bit(idx, cpuc->used_mask);
+
+ perf_event_update_userpage(event);
+}
+
+static void
+armv6pmu_read(struct perf_event *event)
+{
+ struct hw_perf_event *hwc = &event->hw;
+
+ /* Don't read disabled counters! */
+ if (hwc->idx < 0)
+ return;
+
+ armv6pmu_event_update(event, hwc, hwc->idx);
+}
+
+static void
+armv6pmu_unthrottle(struct perf_event *event)
+{
+ struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+ struct hw_perf_event *hwc = &event->hw;
+
+ armv6pmu_enable_event(cpuc, hwc, hwc->idx);
+}
+
+static irqreturn_t
+armv6_perfcounters_irq(int irq_num,
+ void *dev)
+{
+ unsigned long pmcr = pmcr_read();
+ struct perf_sample_data data;
+ struct cpu_hw_events *cpuc;
+ struct pt_regs *regs;
+ int idx;
+
+ if (!pmcr_has_overflowed(pmcr))
+ return IRQ_NONE;
+
+ regs = get_irq_regs();
+
+ /*
+ * The interrupts are cleared by writing the overflow flags back to
+ * the control register. All of the other bits don't have any effect
+ * if they are rewritten, so write the whole value back.
+ */
+ pmcr_write(pmcr);
+
+ data.addr = 0;
+
+ cpuc = &__get_cpu_var(cpu_hw_events);
+ for (idx = 0; idx < ARMV6_MAX_HWEVENTS; ++idx) {
+ struct perf_event *event = cpuc->events[idx];
+ struct hw_perf_event *hwc;
+
+ if (!test_bit(idx, cpuc->active_mask))
+ continue;
+
+ /*
+ * We have a single interrupt for all counters. Check that
+ * each counter has overflowed before we process it.
+ */
+ if (!pmcr_counter_has_overflowed(pmcr, idx))
+ continue;
+
+ hwc = &event->hw;
+ armv6pmu_event_update(event, hwc, idx);
+ data.period = event->hw.last_period;
+ if (!armv6pmu_event_set_period(event, hwc, idx))
+ continue;
+
+ if (perf_event_overflow(event, 0, &data, regs))
+ armv6pmu_disable_event(cpuc, hwc, idx);
+ }
+
+ /*
+ * Handle the pending perf events.
+ *
+ * Note: this call *must* be run with interrupts enabled. For
+ * platforms that can have the PMU interrupts raised as a PMI, this
+ * will not work.
+ */
+ perf_event_do_pending();
+
+ return IRQ_HANDLED;
+}
+
+void
+hw_perf_enable(void)
+{
+ /* Enable all of the perf events on hardware. */
+ int idx;
+ struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+ unsigned long flags, val;
+
+ for (idx = 0; idx < ARMV6_MAX_HWEVENTS; ++idx) {
+ struct perf_event *event = cpuc->events[idx];
+
+ if (!event)
+ continue;
+
+ armv6pmu_enable_event(cpuc, &event->hw, idx);
+ }
+
+ spin_lock_irqsave(&pmu_lock, flags);
+ val = pmcr_read();
+ val |= PMCR_ENABLE;
+ pmcr_write(val);
+ spin_unlock_irqrestore(&pmu_lock, flags);
+}
+
+void
+hw_perf_disable(void)
+{
+ unsigned long flags, val;
+
+ spin_lock_irqsave(&pmu_lock, flags);
+ val = pmcr_read();
+ val &= ~PMCR_ENABLE;
+ pmcr_write(val);
+ spin_unlock_irqrestore(&pmu_lock, flags);
+}
+
+static const struct pmu armv6pmu = {
+ .enable = armv6pmu_enable,
+ .disable = armv6pmu_disable,
+ .read = armv6pmu_read,
+ .unthrottle = armv6pmu_unthrottle,
+};
+
+static int
+validate_event(struct cpu_hw_events *cpuc,
+ struct perf_event *event)
+{
+ struct hw_perf_event fake_event = event->hw;
+
+ if (event->pmu && event->pmu != &armv6pmu)
+ return 0;
+
+ return armv6pmu_place_event(cpuc, &fake_event) >= 0;
+}
+
+static int
+validate_group(struct perf_event *event)
+{
+ struct perf_event *sibling, *leader = event->group_leader;
+ struct cpu_hw_events fake_pmu;
+
+ memset(&fake_pmu, 0, sizeof(fake_pmu));
+
+ if (!validate_event(&fake_pmu, leader))
+ return -ENOSPC;
+
+ list_for_each_entry(sibling, &leader->sibling_list, group_entry) {
+ if (!validate_event(&fake_pmu, sibling))
+ return -ENOSPC;
+ }
+
+ if (!validate_event(&fake_pmu, event))
+ return -ENOSPC;
+
+ return 0;
+}
+
+static int
+armv6_hw_perf_event_init(struct perf_event *event)
+{
+ struct hw_perf_event *hwc = &event->hw;
+ int mapping, err;
+
+ /* Decode the generic type into an ARM event identifier. */
+ if (PERF_TYPE_HARDWARE == event->attr.type) {
+ mapping = armv6_map_hw_event(event->attr.config);
+ } else if (PERF_TYPE_HW_CACHE == event->attr.type) {
+ mapping = armv6_map_cache_event(event->attr.config);
+ } else if (PERF_TYPE_RAW == event->attr.type) {
+ /* The EvtCountN field of the PMCR is 8 bits. */
+ mapping = event->attr.config & 0xFF;
+ } else {
+ pr_debug("event type %x not supported\n", event->attr.type);
+ return -EOPNOTSUPP;
+ }
+
+ if (mapping < 0) {
+ pr_debug("event %x:%llx not supported\n", event->attr.type,
+ event->attr.config);
+ return mapping;
+ }
+
+ /*
+ * Check whether we need to exclude the counter from certain modes.
+ * The ARM performance counters are on all of the time so if someone
+ * has asked us for some excludes then we have to fail.
+ */
+ if (event->attr.exclude_kernel || event->attr.exclude_user ||
+ event->attr.exclude_hv || event->attr.exclude_idle) {
+ pr_debug("ARM performance counters do not support "
+ "mode exclusion\n");
+ return -EPERM;
+ }
+
+ /*
+ * We don't assign an index until we actually place the event onto
+ * hardware. Use -1 to signify that we haven't decided where to put it
+ * yet. For SMP systems, each core has it's own PMU so we can't do any
+ * clever allocation or constraints checking at this point.
+ */
+ hwc->idx = -1;
+
+ /*
+ * Store the event encoding into the config_base field. config and
+ * event_base are unused as the only 2 things we need to know are
+ * the event mapping and the counter to use. The counter to use is
+ * also the indx and the config_base is the event type.
+ */
+ hwc->config_base = (unsigned long)mapping;
+ hwc->config = 0;
+ hwc->event_base = 0;
+
+ if (!hwc->sample_period) {
+ hwc->sample_period = MAX_PERIOD;
+ hwc->last_period = hwc->sample_period;
+ atomic64_set(&hwc->period_left, hwc->sample_period);
+ }
+
+ err = 0;
+ if (event->group_leader != event) {
+ err = validate_group(event);
+ if (err)
+ return -EINVAL;
+ }
+
+ return err;
+}
+
+static int
+armv6pmu_reserve_hardware(void)
+{
+ int i;
+ int err;
+
+ pmu_irqs = reserve_pmu();
+ if (IS_ERR(pmu_irqs)) {
+ pr_warning("unable to reserve pmu\n");
+ return PTR_ERR(pmu_irqs);
+ }
+
+ init_pmu();
+
+ if (pmu_irqs->num_irqs < 1) {
+ pr_err("no irqs for PMUs defined\n");
+ }
+
+ for (i = 0; i < pmu_irqs->num_irqs; ++i) {
+ err = request_irq(pmu_irqs->irqs[i], armv6_perfcounters_irq,
+ IRQF_DISABLED, "armv6_perfctr", NULL);
+ if (err) {
+ pr_warning("unable to request IRQ%d for ARMv6 "
+ "perf counters\n", pmu_irqs->irqs[i]);
+ break;
+ }
+ }
+
+ if (err) {
+ for (i = i - 1; i >= 0; --i)
+ free_irq(pmu_irqs->irqs[i], NULL);
+ release_pmu(pmu_irqs);
+ pmu_irqs = NULL;
+ }
+
+ return err;
+}
+
+static void
+armv6pmu_release_hardware(void)
+{
+ int i;
+
+ for (i = pmu_irqs->num_irqs - 1; i >= 0; --i) {
+ free_irq(pmu_irqs->irqs[i], NULL);
+ }
+ pmcr_write(0);
+
+ release_pmu(pmu_irqs);
+ pmu_irqs = NULL;
+}
+
+static atomic_t active_events = ATOMIC_INIT(0);
+static DEFINE_MUTEX(pmu_reserve_mutex);
+
+static void
+hw_perf_event_destroy(struct perf_event *event)
+{
+ if (atomic_dec_and_mutex_lock(&active_events, &pmu_reserve_mutex)) {
+ armv6pmu_release_hardware();
+ mutex_unlock(&pmu_reserve_mutex);
+ }
+}
+
+const struct pmu *
+hw_perf_event_init(struct perf_event *event)
+{
+ int err = 0;
+
+ /* We support 3 events: one cycle counter and 2 programmable. */
+ perf_max_events = 3;
+ event->destroy = hw_perf_event_destroy;
+
+ if (!atomic_inc_not_zero(&active_events)) {
+ if (atomic_read(&active_events) > perf_max_events) {
+ atomic_dec(&active_events);
+ return ERR_PTR(-ENOSPC);
+ }
+
+ mutex_lock(&pmu_reserve_mutex);
+ if (atomic_read(&active_events) == 0) {
+ err = armv6pmu_reserve_hardware();
+ }
+
+ if (!err)
+ atomic_inc(&active_events);
+ mutex_unlock(&pmu_reserve_mutex);
+ }
+
+ if (err)
+ return ERR_PTR(err);
+
+ err = armv6_hw_perf_event_init(event);
+ if (err)
+ hw_perf_event_destroy(event);
+
+ return err ? ERR_PTR(err) : &armv6pmu;
+}
+
+/* Callchain handling code. */
+static inline void
+callchain_store(struct perf_callchain_entry *entry,
+ u64 ip)
+{
+ if (entry->nr < PERF_MAX_STACK_DEPTH)
+ entry->ip[entry->nr++] = ip;
+}
+
+/*
+ * The registers we're interested in are at the end of the variable
+ * length saved register structure. The fp points at the end of this
+ * structure so the address of this struct is:
+ * (struct frame_tail *)(xxx->fp)-1
+ *
+ * This code has been adapted from the ARM OProfile support.
+ */
+struct frame_tail {
+ struct frame_tail *fp;
+ unsigned long sp;
+ unsigned long lr;
+} __attribute__((packed));
+
+/*
+ * Get the return address for a single stackframe and return a pointer to the
+ * next frame tail.
+ */
+static struct frame_tail *
+user_backtrace(struct frame_tail *tail,
+ struct perf_callchain_entry *entry)
+{
+ struct frame_tail buftail;
+
+ /* Also check accessibility of one struct frame_tail beyond */
+ if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
+ return NULL;
+ if (__copy_from_user_inatomic(&buftail, tail, sizeof(buftail)))
+ return NULL;
+
+ callchain_store(entry, buftail.lr);
+
+ /*
+ * Frame pointers should strictly progress back up the stack
+ * (towards higher addresses).
+ */
+ if (tail >= buftail.fp)
+ return NULL;
+
+ return buftail.fp - 1;
+}
+
+static void
+perf_callchain_user(struct pt_regs *regs,
+ struct perf_callchain_entry *entry)
+{
+ struct frame_tail *tail;
+
+ callchain_store(entry, PERF_CONTEXT_USER);
+
+ if (!user_mode(regs))
+ regs = task_pt_regs(current);
+
+ tail = (struct frame_tail *)regs->ARM_fp - 1;
+
+ while (tail && !((unsigned long)tail & 0x3))
+ tail = user_backtrace(tail, entry);
+}
+
+/*
+ * Gets called by walk_stackframe() for every stackframe. This will be called
+ * whist unwinding the stackframe and is like a subroutine return so we use
+ * the PC.
+ */
+static int
+callchain_trace(struct stackframe *fr,
+ void *data)
+{
+ struct perf_callchain_entry *entry = data;
+ callchain_store(entry, fr->pc);
+ return 0;
+}
+
+static void
+perf_callchain_kernel(struct pt_regs *regs,
+ struct perf_callchain_entry *entry)
+{
+ struct stackframe fr;
+
+ callchain_store(entry, PERF_CONTEXT_KERNEL);
+ fr.fp = regs->ARM_fp;
+ fr.sp = regs->ARM_sp;
+ fr.lr = regs->ARM_lr;
+ fr.pc = regs->ARM_pc;
+ walk_stackframe(&fr, callchain_trace, entry);
+}
+
+static void
+perf_do_callchain(struct pt_regs *regs,
+ struct perf_callchain_entry *entry)
+{
+ int is_user;
+
+ if (!regs)
+ return;
+
+ is_user = user_mode(regs);
+
+ if (!current || !current->pid)
+ return;
+
+ if (is_user && current->state != TASK_RUNNING)
+ return;
+
+ if (!is_user)
+ perf_callchain_kernel(regs, entry);
+
+ if (current->mm)
+ perf_callchain_user(regs, entry);
+}
+
+static DEFINE_PER_CPU(struct perf_callchain_entry, pmc_irq_entry);
+
+struct perf_callchain_entry *
+perf_callchain(struct pt_regs *regs)
+{
+ struct perf_callchain_entry *entry = &__get_cpu_var(pmc_irq_entry);
+
+ entry->nr = 0;
+ perf_do_callchain(regs, entry);
+ return entry;
+}
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index fc5c05b..89a26ea 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -791,3 +791,11 @@ config ARM_L1_CACHE_SHIFT
int
default 6 if ARCH_OMAP3 || ARCH_S5PC1XX
default 5
+
+config HW_PERF_EVENTS
+ bool "Enable hardware performance counter support for perf events"
+ depends on PERF_EVENTS && CPU_HAS_PMU && CPU_V6
+ default n
+ help
+ Enable hardware performance counter support for perf events. If
+ disabled, perf events will use software events only.
--
1.6.5.4
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