arch/arm/kernel/perf_event.c

#undef DEBUG

/*
 * ARM 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) "hw perfevents: " fmt

#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/perf_event.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>

#include <asm/cputype.h>
#include <asm/irq.h>
#include <asm/irq_regs.h>
#include <asm/pmu.h>
#include <asm/stacktrace.h>

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);

/*
 * ARMv6 supports a maximum of 3 events, starting from index 1. If we add
 * another platform that supports more, we need to increase this to be the
 * largest of all platforms.
 */
#define ARMPMU_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[ARMPMU_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(ARMPMU_MAX_HWEVENTS)];

	/*
	 * A 1 bit for an index indicates that the counter is actively being
	 * used.
	 */
	unsigned long		active_mask[BITS_TO_LONGS(ARMPMU_MAX_HWEVENTS)];
};
DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);

struct arm_pmu {
	const char	*name;
	irqreturn_t	(*handle_irq)(int irq_num, void *dev);
	void		(*enable)(struct hw_perf_event *evt, int idx);
	void		(*disable)(struct hw_perf_event *evt, int idx);
	int		(*event_map)(int evt);
	u64		(*raw_event)(u64);
	int		(*get_event_idx)(struct cpu_hw_events *cpuc,
					 struct hw_perf_event *hwc);
	u32		(*read_counter)(int idx);
	void		(*write_counter)(int idx, u32 val);
	void		(*start)(void);
	void		(*stop)(void);
	int		num_events;
	u64		max_period;
};

/* Set at runtime when we know what CPU type we are. */
static const struct arm_pmu *armpmu;

#define HW_OP_UNSUPPORTED		0xFFFF

#define C(_x) \
	PERF_COUNT_HW_CACHE_##_x

#define CACHE_OP_UNSUPPORTED		0xFFFF

static unsigned armpmu_perf_cache_map[PERF_COUNT_HW_CACHE_MAX]
				     [PERF_COUNT_HW_CACHE_OP_MAX]
				     [PERF_COUNT_HW_CACHE_RESULT_MAX];

static int
armpmu_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)armpmu_perf_cache_map[cache_type][cache_op][cache_result];

	if (ret == CACHE_OP_UNSUPPORTED)
		return -ENOENT;

	return ret;
}

static int
armpmu_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 > (s64)armpmu->max_period)
		left = armpmu->max_period;

	atomic64_set(&hwc->prev_count, (u64)-left);

	armpmu->write_counter(idx, (u64)(-left) & 0xffffffff);

	perf_event_update_userpage(event);

	return ret;
}

static u64
armpmu_event_update(struct perf_event *event,
		    struct hw_perf_event *hwc,
		    int idx)
{
	int shift = 64 - 32;
	s64 prev_raw_count, new_raw_count;
	s64 delta;

again:
	prev_raw_count = atomic64_read(&hwc->prev_count);
	new_raw_count = armpmu->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
armpmu_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);
	armpmu->disable(hwc, idx);

	barrier();

	armpmu_event_update(event, hwc, idx);
	cpuc->events[idx] = NULL;
	clear_bit(idx, cpuc->used_mask);

	perf_event_update_userpage(event);
}

static void
armpmu_read(struct perf_event *event)
{
	struct hw_perf_event *hwc = &event->hw;

	/* Don't read disabled counters! */
	if (hwc->idx < 0)
		return;

	armpmu_event_update(event, hwc, hwc->idx);
}

static void
armpmu_unthrottle(struct perf_event *event)
{
	struct hw_perf_event *hwc = &event->hw;

	/*
	 * Set the period again. Some counters can't be stopped, so when we
	 * were throttled we simply disabled the IRQ source and the counter
	 * may have been left counting. If we don't do this step then we may
	 * get an interrupt too soon or *way* too late if the overflow has
	 * happened since disabling.
	 */
	armpmu_event_set_period(event, hwc, hwc->idx);
	armpmu->enable(hwc, hwc->idx);
}

static int
armpmu_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 = armpmu->get_event_idx(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;
	armpmu->disable(hwc, idx);
	cpuc->events[idx] = event;
	set_bit(idx, cpuc->active_mask);

	/* Set the period for the event. */
	armpmu_event_set_period(event, hwc, idx);

	/* Enable the event. */
	armpmu->enable(hwc, idx);

	/* Propagate our changes to the userspace mapping. */
	perf_event_update_userpage(event);

out:
	return err;
}

static struct pmu pmu = {
	.enable	    = armpmu_enable,
	.disable    = armpmu_disable,
	.unthrottle = armpmu_unthrottle,
	.read	    = armpmu_read,
};

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 != &pmu)
		return 0;

	return armpmu->get_event_idx(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
armpmu_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");
		return -ENODEV;
	}

	for (i = 0; i < pmu_irqs->num_irqs; ++i) {
		err = request_irq(pmu_irqs->irqs[i], armpmu->handle_irq,
				  IRQF_DISABLED, "armpmu", NULL);
		if (err) {
			pr_warning("unable to request IRQ%d for ARM "
				   "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
armpmu_release_hardware(void)
{
	int i;

	for (i = pmu_irqs->num_irqs - 1; i >= 0; --i)
		free_irq(pmu_irqs->irqs[i], NULL);
	armpmu->stop();

	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)) {
		armpmu_release_hardware();
		mutex_unlock(&pmu_reserve_mutex);
	}
}

static int
__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 = armpmu->event_map(event->attr.config);
	} else if (PERF_TYPE_HW_CACHE == event->attr.type) {
		mapping = armpmu_map_cache_event(event->attr.config);
	} else if (PERF_TYPE_RAW == event->attr.type) {
		mapping = armpmu->raw_event(event->attr.config);
	} 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  = armpmu->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;
}

const struct pmu *
hw_perf_event_init(struct perf_event *event)
{
	int err = 0;

	if (!armpmu)
		return ERR_PTR(-ENODEV);

	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 = armpmu_reserve_hardware();
		}

		if (!err)
			atomic_inc(&active_events);
		mutex_unlock(&pmu_reserve_mutex);
	}

	if (err)
		return ERR_PTR(err);

	err = __hw_perf_event_init(event);
	if (err)
		hw_perf_event_destroy(event);

	return err ? ERR_PTR(err) : &pmu;
}

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);

	if (!armpmu)
		return;

	for (idx = 0; idx <= armpmu->num_events; ++idx) {
		struct perf_event *event = cpuc->events[idx];

		if (!event)
			continue;

		armpmu->enable(&event->hw, idx);
	}

	armpmu->start();
}

void
hw_perf_disable(void)
{
	if (armpmu)
		armpmu->stop();
}

/*
 * ARMv6 Performance counter handling code.
 *
 * 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.
 */

enum armv6_perf_types {
	ARMV6_PERFCTR_ICACHE_MISS	    = 0x0,
	ARMV6_PERFCTR_IBUF_STALL	    = 0x1,
	ARMV6_PERFCTR_DDEP_STALL	    = 0x2,
	ARMV6_PERFCTR_ITLB_MISS		    = 0x3,
	ARMV6_PERFCTR_DTLB_MISS		    = 0x4,
	ARMV6_PERFCTR_BR_EXEC		    = 0x5,
	ARMV6_PERFCTR_BR_MISPREDICT	    = 0x6,
	ARMV6_PERFCTR_INSTR_EXEC	    = 0x7,
	ARMV6_PERFCTR_DCACHE_HIT	    = 0x9,
	ARMV6_PERFCTR_DCACHE_ACCESS	    = 0xA,
	ARMV6_PERFCTR_DCACHE_MISS	    = 0xB,
	ARMV6_PERFCTR_DCACHE_WBACK	    = 0xC,
	ARMV6_PERFCTR_SW_PC_CHANGE	    = 0xD,
	ARMV6_PERFCTR_MAIN_TLB_MISS	    = 0xF,
	ARMV6_PERFCTR_EXPL_D_ACCESS	    = 0x10,
	ARMV6_PERFCTR_LSU_FULL_STALL	    = 0x11,
	ARMV6_PERFCTR_WBUF_DRAINED	    = 0x12,
	ARMV6_PERFCTR_CPU_CYCLES	    = 0xFF,
	ARMV6_PERFCTR_NOP		    = 0x20,
};

enum armv6_counters {
	ARMV6_CYCLE_COUNTER = 1,
	ARMV6_COUNTER0,
	ARMV6_COUNTER1,
};

/*
 * 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 armv6_perf_map[PERF_COUNT_HW_MAX] = {
	[PERF_COUNT_HW_CPU_CYCLES]	    = ARMV6_PERFCTR_CPU_CYCLES,
	[PERF_COUNT_HW_INSTRUCTIONS]	    = ARMV6_PERFCTR_INSTR_EXEC,
	[PERF_COUNT_HW_CACHE_REFERENCES]    = HW_OP_UNSUPPORTED,
	[PERF_COUNT_HW_CACHE_MISSES]	    = HW_OP_UNSUPPORTED,
	[PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = ARMV6_PERFCTR_BR_EXEC,
	[PERF_COUNT_HW_BRANCH_MISSES]	    = ARMV6_PERFCTR_BR_MISPREDICT,
	[PERF_COUNT_HW_BUS_CYCLES]	    = HW_OP_UNSUPPORTED,
};

static const unsigned armv6_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)]	= ARMV6_PERFCTR_DCACHE_ACCESS,
			[C(RESULT_MISS)]	= ARMV6_PERFCTR_DCACHE_MISS,
		},
		[C(OP_WRITE)] = {
			[C(RESULT_ACCESS)]	= ARMV6_PERFCTR_DCACHE_ACCESS,
			[C(RESULT_MISS)]	= ARMV6_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)]	= ARMV6_PERFCTR_ICACHE_MISS,
		},
		[C(OP_WRITE)] = {
			[C(RESULT_ACCESS)]	= CACHE_OP_UNSUPPORTED,
			[C(RESULT_MISS)]	= ARMV6_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)]	= ARMV6_PERFCTR_DTLB_MISS,
		},
		[C(OP_WRITE)] = {
			[C(RESULT_ACCESS)]	= CACHE_OP_UNSUPPORTED,
			[C(RESULT_MISS)]	= ARMV6_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)]	= ARMV6_PERFCTR_ITLB_MISS,
		},
		[C(OP_WRITE)] = {
			[C(RESULT_ACCESS)]	= CACHE_OP_UNSUPPORTED,
			[C(RESULT_MISS)]	= ARMV6_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,
		},
	},
};

enum armv6mpcore_perf_types {
	ARMV6MPCORE_PERFCTR_ICACHE_MISS	    = 0x0,
	ARMV6MPCORE_PERFCTR_IBUF_STALL	    = 0x1,
	ARMV6MPCORE_PERFCTR_DDEP_STALL	    = 0x2,
	ARMV6MPCORE_PERFCTR_ITLB_MISS	    = 0x3,
	ARMV6MPCORE_PERFCTR_DTLB_MISS	    = 0x4,
	ARMV6MPCORE_PERFCTR_BR_EXEC	    = 0x5,
	ARMV6MPCORE_PERFCTR_BR_NOTPREDICT   = 0x6,
	ARMV6MPCORE_PERFCTR_BR_MISPREDICT   = 0x7,
	ARMV6MPCORE_PERFCTR_INSTR_EXEC	    = 0x8,
	ARMV6MPCORE_PERFCTR_DCACHE_RDACCESS = 0xA,
	ARMV6MPCORE_PERFCTR_DCACHE_RDMISS   = 0xB,
	ARMV6MPCORE_PERFCTR_DCACHE_WRACCESS = 0xC,
	ARMV6MPCORE_PERFCTR_DCACHE_WRMISS   = 0xD,
	ARMV6MPCORE_PERFCTR_DCACHE_EVICTION = 0xE,
	ARMV6MPCORE_PERFCTR_SW_PC_CHANGE    = 0xF,
	ARMV6MPCORE_PERFCTR_MAIN_TLB_MISS   = 0x10,
	ARMV6MPCORE_PERFCTR_EXPL_MEM_ACCESS = 0x11,
	ARMV6MPCORE_PERFCTR_LSU_FULL_STALL  = 0x12,
	ARMV6MPCORE_PERFCTR_WBUF_DRAINED    = 0x13,
	ARMV6MPCORE_PERFCTR_CPU_CYCLES	    = 0xFF,
};

/*
 * 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 armv6mpcore_perf_map[PERF_COUNT_HW_MAX] = {
	[PERF_COUNT_HW_CPU_CYCLES]	    = ARMV6MPCORE_PERFCTR_CPU_CYCLES,
	[PERF_COUNT_HW_INSTRUCTIONS]	    = ARMV6MPCORE_PERFCTR_INSTR_EXEC,
	[PERF_COUNT_HW_CACHE_REFERENCES]    = HW_OP_UNSUPPORTED,
	[PERF_COUNT_HW_CACHE_MISSES]	    = HW_OP_UNSUPPORTED,
	[PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = ARMV6MPCORE_PERFCTR_BR_EXEC,
	[PERF_COUNT_HW_BRANCH_MISSES]	    = ARMV6MPCORE_PERFCTR_BR_MISPREDICT,
	[PERF_COUNT_HW_BUS_CYCLES]	    = HW_OP_UNSUPPORTED,
};

static const unsigned armv6mpcore_perf_cache_map[PERF_COUNT_HW_CACHE_MAX]
					[PERF_COUNT_HW_CACHE_OP_MAX]
					[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
	[C(L1D)] = {
		[C(OP_READ)] = {
			[C(RESULT_ACCESS)]  =
				ARMV6MPCORE_PERFCTR_DCACHE_RDACCESS,
			[C(RESULT_MISS)]    =
				ARMV6MPCORE_PERFCTR_DCACHE_RDMISS,
		},
		[C(OP_WRITE)] = {
			[C(RESULT_ACCESS)]  =
				ARMV6MPCORE_PERFCTR_DCACHE_WRACCESS,
			[C(RESULT_MISS)]    =
				ARMV6MPCORE_PERFCTR_DCACHE_WRMISS,
		},
		[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)]    = ARMV6MPCORE_PERFCTR_ICACHE_MISS,
		},
		[C(OP_WRITE)] = {
			[C(RESULT_ACCESS)]  = CACHE_OP_UNSUPPORTED,
			[C(RESULT_MISS)]    = ARMV6MPCORE_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)]    = ARMV6MPCORE_PERFCTR_DTLB_MISS,
		},
		[C(OP_WRITE)] = {
			[C(RESULT_ACCESS)]  = CACHE_OP_UNSUPPORTED,
			[C(RESULT_MISS)]    = ARMV6MPCORE_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)]    = ARMV6MPCORE_PERFCTR_ITLB_MISS,
		},
		[C(OP_WRITE)] = {
			[C(RESULT_ACCESS)]  = CACHE_OP_UNSUPPORTED,
			[C(RESULT_MISS)]    = ARMV6MPCORE_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 inline unsigned long
armv6_pmcr_read(void)
{
	u32 val;
	asm volatile("mrc   p15, 0, %0, c15, c12, 0" : "=r"(val));
	return val;
}

static inline void
armv6_pmcr_write(unsigned long val)
{
	asm volatile("mcr   p15, 0, %0, c15, c12, 0" : : "r"(val));
}

#define ARMV6_PMCR_ENABLE		(1 << 0)
#define ARMV6_PMCR_CTR01_RESET		(1 << 1)
#define ARMV6_PMCR_CCOUNT_RESET		(1 << 2)
#define ARMV6_PMCR_CCOUNT_DIV		(1 << 3)
#define ARMV6_PMCR_COUNT0_IEN		(1 << 4)
#define ARMV6_PMCR_COUNT1_IEN		(1 << 5)
#define ARMV6_PMCR_CCOUNT_IEN		(1 << 6)
#define ARMV6_PMCR_COUNT0_OVERFLOW	(1 << 8)
#define ARMV6_PMCR_COUNT1_OVERFLOW	(1 << 9)
#define ARMV6_PMCR_CCOUNT_OVERFLOW	(1 << 10)
#define ARMV6_PMCR_EVT_COUNT0_SHIFT	20
#define ARMV6_PMCR_EVT_COUNT0_MASK	(0xFF << ARMV6_PMCR_EVT_COUNT0_SHIFT)
#define ARMV6_PMCR_EVT_COUNT1_SHIFT	12
#define ARMV6_PMCR_EVT_COUNT1_MASK	(0xFF << ARMV6_PMCR_EVT_COUNT1_SHIFT)

#define ARMV6_PMCR_OVERFLOWED_MASK \
	(ARMV6_PMCR_COUNT0_OVERFLOW | ARMV6_PMCR_COUNT1_OVERFLOW | \
	 ARMV6_PMCR_CCOUNT_OVERFLOW)

static inline int
armv6_pmcr_has_overflowed(unsigned long pmcr)
{
	return (pmcr & ARMV6_PMCR_OVERFLOWED_MASK);
}

static inline int
armv6_pmcr_counter_has_overflowed(unsigned long pmcr,
				  enum armv6_counters counter)
{
	int ret = 0;

	if (ARMV6_CYCLE_COUNTER == counter)
		ret = pmcr & ARMV6_PMCR_CCOUNT_OVERFLOW;
	else if (ARMV6_COUNTER0 == counter)
		ret = pmcr & ARMV6_PMCR_COUNT0_OVERFLOW;
	else if (ARMV6_COUNTER1 == counter)
		ret = pmcr & ARMV6_PMCR_COUNT1_OVERFLOW;
	else
		WARN_ONCE(1, "invalid counter number (%d)\n", counter);

	return ret;
}

static inline u32
armv6pmu_read_counter(int counter)
{
	unsigned long value = 0;

	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
		WARN_ONCE(1, "invalid counter number (%d)\n", counter);

	return value;
}

static inline void
armv6pmu_write_counter(int counter,
		       u32 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
		WARN_ONCE(1, "invalid counter number (%d)\n", counter);
}

void
armv6pmu_enable_event(struct hw_perf_event *hwc,
		      int idx)
{
	unsigned long val, mask, evt, flags;

	if (ARMV6_CYCLE_COUNTER == idx) {
		mask	= 0;
		evt	= ARMV6_PMCR_CCOUNT_IEN;
	} else if (ARMV6_COUNTER0 == idx) {
		mask	= ARMV6_PMCR_EVT_COUNT0_MASK;
		evt	= (hwc->config_base << ARMV6_PMCR_EVT_COUNT0_SHIFT) |
			  ARMV6_PMCR_COUNT0_IEN;
	} else if (ARMV6_COUNTER1 == idx) {
		mask	= ARMV6_PMCR_EVT_COUNT1_MASK;
		evt	= (hwc->config_base << ARMV6_PMCR_EVT_COUNT1_SHIFT) |
			  ARMV6_PMCR_COUNT1_IEN;
	} else {
		WARN_ONCE(1, "invalid counter number (%d)\n", idx);
		return;
	}

	/*
	 * 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 = armv6_pmcr_read();
	val &= ~mask;
	val |= evt;
	armv6_pmcr_write(val);
	spin_unlock_irqrestore(&pmu_lock, flags);
}

static irqreturn_t
armv6pmu_handle_irq(int irq_num,
		    void *dev)
{
	unsigned long pmcr = armv6_pmcr_read();
	struct perf_sample_data data;
	struct cpu_hw_events *cpuc;
	struct pt_regs *regs;
	int idx;

	if (!armv6_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.
	 */
	armv6_pmcr_write(pmcr);

	data.addr = 0;

	cpuc = &__get_cpu_var(cpu_hw_events);
	for (idx = 0; idx <= armpmu->num_events; ++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 (!armv6_pmcr_counter_has_overflowed(pmcr, idx))
			continue;

		hwc = &event->hw;
		armpmu_event_update(event, hwc, idx);
		data.period = event->hw.last_period;
		if (!armpmu_event_set_period(event, hwc, idx))
			continue;

		if (perf_event_overflow(event, 0, &data, regs))
			armpmu->disable(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;
}

static void
armv6pmu_start(void)
{
	unsigned long flags, val;

	spin_lock_irqsave(&pmu_lock, flags);
	val = armv6_pmcr_read();
	val |= ARMV6_PMCR_ENABLE;
	armv6_pmcr_write(val);
	spin_unlock_irqrestore(&pmu_lock, flags);
}

void
armv6pmu_stop(void)
{
	unsigned long flags, val;

	spin_lock_irqsave(&pmu_lock, flags);
	val = armv6_pmcr_read();
	val &= ~ARMV6_PMCR_ENABLE;
	armv6_pmcr_write(val);
	spin_unlock_irqrestore(&pmu_lock, flags);
}

static inline int
armv6pmu_event_map(int config)
{
	int mapping = armv6_perf_map[config];
	if (HW_OP_UNSUPPORTED == mapping)
		mapping = -EOPNOTSUPP;
	return mapping;
}

static inline int
armv6mpcore_pmu_event_map(int config)
{
	int mapping = armv6mpcore_perf_map[config];
	if (HW_OP_UNSUPPORTED == mapping)
		mapping = -EOPNOTSUPP;
	return mapping;
}

static u64
armv6pmu_raw_event(u64 config)
{
	return config & 0xff;
}

static int
armv6pmu_get_event_idx(struct cpu_hw_events *cpuc,
		       struct hw_perf_event *event)
{
	/* Always place a cycle counter into the cycle counter. */
	if (ARMV6_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 hw_perf_event *hwc,
		       int idx)
{
	unsigned long val, mask, evt, flags;

	if (ARMV6_CYCLE_COUNTER == idx) {
		mask	= ARMV6_PMCR_CCOUNT_IEN;
		evt	= 0;
	} else if (ARMV6_COUNTER0 == idx) {
		mask	= ARMV6_PMCR_COUNT0_IEN | ARMV6_PMCR_EVT_COUNT0_MASK;
		evt	= ARMV6_PERFCTR_NOP << ARMV6_PMCR_EVT_COUNT0_SHIFT;
	} else if (ARMV6_COUNTER1 == idx) {
		mask	= ARMV6_PMCR_COUNT1_IEN | ARMV6_PMCR_EVT_COUNT1_MASK;
		evt	= ARMV6_PERFCTR_NOP << ARMV6_PMCR_EVT_COUNT1_SHIFT;
	} else {
		WARN_ONCE(1, "invalid counter number (%d)\n", idx);
		return;
	}

	/*
	 * 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 = armv6_pmcr_read();
	val &= ~mask;
	val |= evt;
	armv6_pmcr_write(val);
	spin_unlock_irqrestore(&pmu_lock, flags);
}

static void
armv6mpcore_pmu_disable_event(struct hw_perf_event *hwc,
			      int idx)
{
	unsigned long val, mask, flags, evt = 0;

	if (ARMV6_CYCLE_COUNTER == idx) {
		mask	= ARMV6_PMCR_CCOUNT_IEN;
	} else if (ARMV6_COUNTER0 == idx) {
		mask	= ARMV6_PMCR_COUNT0_IEN;
	} else if (ARMV6_COUNTER1 == idx) {
		mask	= ARMV6_PMCR_COUNT1_IEN;
	} else {
		WARN_ONCE(1, "invalid counter number (%d)\n", idx);
		return;
	}

	/*
	 * Unlike UP ARMv6, we don't have a way of stopping the counters. We
	 * simply disable the interrupt reporting.
	 */
	spin_lock_irqsave(&pmu_lock, flags);
	val = armv6_pmcr_read();
	val &= ~mask;
	val |= evt;
	armv6_pmcr_write(val);
	spin_unlock_irqrestore(&pmu_lock, flags);
}

static const struct arm_pmu armv6pmu = {
	.name			= "v6",
	.handle_irq		= armv6pmu_handle_irq,
	.enable			= armv6pmu_enable_event,
	.disable		= armv6pmu_disable_event,
	.event_map		= armv6pmu_event_map,
	.raw_event		= armv6pmu_raw_event,
	.read_counter		= armv6pmu_read_counter,
	.write_counter		= armv6pmu_write_counter,
	.get_event_idx		= armv6pmu_get_event_idx,
	.start			= armv6pmu_start,
	.stop			= armv6pmu_stop,
	.num_events		= 3,
	.max_period		= (1LLU << 32) - 1,
};

/*
 * ARMv6mpcore is almost identical to single core ARMv6 with the exception
 * that some of the events have different enumerations and that there is no
 * *hack* to stop the programmable counters. To stop the counters we simply
 * disable the interrupt reporting and update the event. When unthrottling we
 * reset the period and enable the interrupt reporting.
 */
static const struct arm_pmu armv6mpcore_pmu = {
	.name			= "v6mpcore",
	.handle_irq		= armv6pmu_handle_irq,
	.enable			= armv6pmu_enable_event,
	.disable		= armv6mpcore_pmu_disable_event,
	.event_map		= armv6mpcore_pmu_event_map,
	.raw_event		= armv6pmu_raw_event,
	.read_counter		= armv6pmu_read_counter,
	.write_counter		= armv6pmu_write_counter,
	.get_event_idx		= armv6pmu_get_event_idx,
	.start			= armv6pmu_start,
	.stop			= armv6pmu_stop,
	.num_events		= 3,
	.max_period		= (1LLU << 32) - 1,
};

static int __init
init_hw_perf_events(void)
{
	unsigned long cpuid = read_cpuid_id();
	unsigned long implementor = (cpuid & 0xFF000000) >> 24;
	unsigned long part_number = (cpuid & 0xFFF0);

	/* We only support ARM CPUs implemented by ARM at the moment. */
	if (0x41 == implementor) {
		switch (part_number) {
		case 0xB360:	/* ARM1136 */
		case 0xB560:	/* ARM1156 */
		case 0xB760:	/* ARM1176 */
			armpmu = &armv6pmu;
			memcpy(armpmu_perf_cache_map, armv6_perf_cache_map,
					sizeof(armv6_perf_cache_map));
			perf_max_events	= armv6pmu.num_events;
			break;
		case 0xB020:	/* ARM11mpcore */
			armpmu = &armv6mpcore_pmu;
			memcpy(armpmu_perf_cache_map,
			       armv6mpcore_perf_cache_map,
			       sizeof(armv6mpcore_perf_cache_map));
			perf_max_events = armv6mpcore_pmu.num_events;
			break;
		default:
			pr_info("no hardware support available\n");
			perf_max_events = -1;
		}
	}

	if (armpmu)
		pr_info("enabled with %s PMU driver\n",
				armpmu->name);

	return 0;
}
arch_initcall(init_hw_perf_events);

/*
 * 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;
}