arch/arm/kernel/perf_event.c - linux - Git at Google

 #undef DEBUG

 /*
  * ARM performance counter support.
  *
  * Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
  * Copyright (C) 2010 ARM Ltd., Will Deacon <will.deacon@arm.com>
  *
  * 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/kernel.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/uaccess.h>

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

 static int
 armpmu_map_cache_event(const unsigned (*cache_map)
 				      [PERF_COUNT_HW_CACHE_MAX]
 				      [PERF_COUNT_HW_CACHE_OP_MAX]
 				      [PERF_COUNT_HW_CACHE_RESULT_MAX],
 		       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)(*cache_map)[cache_type][cache_op][cache_result];

 	if (ret == CACHE_OP_UNSUPPORTED)
 		return -ENOENT;

 	return ret;
 }

 static int
 armpmu_map_hw_event(const unsigned (*event_map)[PERF_COUNT_HW_MAX], u64 config)
 {
 	int mapping = (*event_map)[config];
 	return mapping == HW_OP_UNSUPPORTED ? -ENOENT : mapping;
 }

 static int
 armpmu_map_raw_event(u32 raw_event_mask, u64 config)
 {
 	return (int)(config & raw_event_mask);
 }

 int
 armpmu_map_event(struct perf_event *event,
 		 const unsigned (*event_map)[PERF_COUNT_HW_MAX],
 		 const unsigned (*cache_map)
 				[PERF_COUNT_HW_CACHE_MAX]
 				[PERF_COUNT_HW_CACHE_OP_MAX]
 				[PERF_COUNT_HW_CACHE_RESULT_MAX],
 		 u32 raw_event_mask)
 {
 	u64 config = event->attr.config;

 	switch (event->attr.type) {
 	case PERF_TYPE_HARDWARE:
 		return armpmu_map_hw_event(event_map, config);
 	case PERF_TYPE_HW_CACHE:
 		return armpmu_map_cache_event(cache_map, config);
 	case PERF_TYPE_RAW:
 		return armpmu_map_raw_event(raw_event_mask, config);
 	}

 	return -ENOENT;
 }

 int armpmu_event_set_period(struct perf_event *event)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
 	struct hw_perf_event *hwc = &event->hw;
 	s64 left = local64_read(&hwc->period_left);
 	s64 period = hwc->sample_period;
 	int ret = 0;

 	/* The period may have been changed by PERF_EVENT_IOC_PERIOD */
 	if (unlikely(period != hwc->last_period))
 		left = period - (hwc->last_period - left);

 	if (unlikely(left <= -period)) {
 		left = period;
 		local64_set(&hwc->period_left, left);
 		hwc->last_period = period;
 		ret = 1;
 	}

 	if (unlikely(left <= 0)) {
 		left += period;
 		local64_set(&hwc->period_left, left);
 		hwc->last_period = period;
 		ret = 1;
 	}

 	if (left > (s64)armpmu->max_period)
 		left = armpmu->max_period;

 	local64_set(&hwc->prev_count, (u64)-left);

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

 	perf_event_update_userpage(event);

 	return ret;
 }

 u64 armpmu_event_update(struct perf_event *event)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
 	struct hw_perf_event *hwc = &event->hw;
 	u64 delta, prev_raw_count, new_raw_count;

 again:
 	prev_raw_count = local64_read(&hwc->prev_count);
 	new_raw_count = armpmu->read_counter(event);

 	if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
 			     new_raw_count) != prev_raw_count)
 		goto again;

 	delta = (new_raw_count - prev_raw_count) & armpmu->max_period;

 	local64_add(delta, &event->count);
 	local64_sub(delta, &hwc->period_left);

 	return new_raw_count;
 }

 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);
 }

 static void
 armpmu_stop(struct perf_event *event, int flags)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
 	struct hw_perf_event *hwc = &event->hw;

 	/*
 	 * ARM pmu always has to update the counter, so ignore
 	 * PERF_EF_UPDATE, see comments in armpmu_start().
 	 */
 	if (!(hwc->state & PERF_HES_STOPPED)) {
 		armpmu->disable(event);
 		armpmu_event_update(event);
 		hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
 	}
 }

 static void armpmu_start(struct perf_event *event, int flags)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
 	struct hw_perf_event *hwc = &event->hw;

 	/*
 	 * ARM pmu always has to reprogram the period, so ignore
 	 * PERF_EF_RELOAD, see the comment below.
 	 */
 	if (flags & PERF_EF_RELOAD)
 		WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));

 	hwc->state = 0;
 	/*
 	 * Set the period again. Some counters can't be stopped, so when we
 	 * were stopped 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);
 	armpmu->enable(event);
 }

 static void
 armpmu_del(struct perf_event *event, int flags)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
 	struct pmu_hw_events *hw_events = armpmu->get_hw_events();
 	struct hw_perf_event *hwc = &event->hw;
 	int idx = hwc->idx;

 	WARN_ON(idx < 0);

 	armpmu_stop(event, PERF_EF_UPDATE);
 	hw_events->events[idx] = NULL;
 	clear_bit(idx, hw_events->used_mask);

 	perf_event_update_userpage(event);
 }

 static int
 armpmu_add(struct perf_event *event, int flags)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
 	struct pmu_hw_events *hw_events = armpmu->get_hw_events();
 	struct hw_perf_event *hwc = &event->hw;
 	int idx;
 	int err = 0;

 	perf_pmu_disable(event->pmu);

 	/* If we don't have a space for the counter then finish early. */
 	idx = armpmu->get_event_idx(hw_events, event);
 	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(event);
 	hw_events->events[idx] = event;

 	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
 	if (flags & PERF_EF_START)
 		armpmu_start(event, PERF_EF_RELOAD);

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

 out:
 	perf_pmu_enable(event->pmu);
 	return err;
 }

 static int
 validate_event(struct pmu_hw_events *hw_events,
 	       struct perf_event *event)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
 	struct pmu *leader_pmu = event->group_leader->pmu;

 	if (event->pmu != leader_pmu || event->state <= PERF_EVENT_STATE_OFF)
 		return 1;

 	return armpmu->get_event_idx(hw_events, event) >= 0;
 }

 static int
 validate_group(struct perf_event *event)
 {
 	struct perf_event *sibling, *leader = event->group_leader;
 	struct pmu_hw_events fake_pmu;
 	DECLARE_BITMAP(fake_used_mask, ARMPMU_MAX_HWEVENTS);

 	/*
 	 * Initialise the fake PMU. We only need to populate the
 	 * used_mask for the purposes of validation.
 	 */
 	memset(fake_used_mask, 0, sizeof(fake_used_mask));
 	fake_pmu.used_mask = fake_used_mask;

 	if (!validate_event(&fake_pmu, leader))
 		return -EINVAL;

 	list_for_each_entry(sibling, &leader->sibling_list, group_entry) {
 		if (!validate_event(&fake_pmu, sibling))
 			return -EINVAL;
 	}

 	if (!validate_event(&fake_pmu, event))
 		return -EINVAL;

 	return 0;
 }

 static irqreturn_t armpmu_dispatch_irq(int irq, void *dev)
 {
 	struct arm_pmu *armpmu = (struct arm_pmu *) dev;
 	struct platform_device *plat_device = armpmu->plat_device;
 	struct arm_pmu_platdata *plat = dev_get_platdata(&plat_device->dev);

 	if (plat && plat->handle_irq)
 		return plat->handle_irq(irq, dev, armpmu->handle_irq);
 	else
 		return armpmu->handle_irq(irq, dev);
 }

 static void
 armpmu_release_hardware(struct arm_pmu *armpmu)
 {
 	armpmu->free_irq(armpmu);
 	pm_runtime_put_sync(&armpmu->plat_device->dev);
 }

 static int
 armpmu_reserve_hardware(struct arm_pmu *armpmu)
 {
 	int err;
 	struct platform_device *pmu_device = armpmu->plat_device;

 	if (!pmu_device)
 		return -ENODEV;

 	pm_runtime_get_sync(&pmu_device->dev);
 	err = armpmu->request_irq(armpmu, armpmu_dispatch_irq);
 	if (err) {
 		armpmu_release_hardware(armpmu);
 		return err;
 	}

 	return 0;
 }

 static void
 hw_perf_event_destroy(struct perf_event *event)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
 	atomic_t *active_events	 = &armpmu->active_events;
 	struct mutex *pmu_reserve_mutex = &armpmu->reserve_mutex;

 	if (atomic_dec_and_mutex_lock(active_events, pmu_reserve_mutex)) {
 		armpmu_release_hardware(armpmu);
 		mutex_unlock(pmu_reserve_mutex);
 	}
 }

 static int
 event_requires_mode_exclusion(struct perf_event_attr *attr)
 {
 	return attr->exclude_idle || attr->exclude_user ||
 	       attr->exclude_kernel || attr->exclude_hv;
 }

 static int
 __hw_perf_event_init(struct perf_event *event)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
 	struct hw_perf_event *hwc = &event->hw;
 	int mapping, err;

 	mapping = armpmu->map_event(event);

 	if (mapping < 0) {
 		pr_debug("event %x:%llx not supported\n", event->attr.type,
 			 event->attr.config);
 		return mapping;
 	}

 	/*
 	 * 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;
 	hwc->config_base	= 0;
 	hwc->config		= 0;
 	hwc->event_base		= 0;

 	/*
 	 * Check whether we need to exclude the counter from certain modes.
 	 */
 	if ((!armpmu->set_event_filter ||
 	     armpmu->set_event_filter(hwc, &event->attr)) &&
 	     event_requires_mode_exclusion(&event->attr)) {
 		pr_debug("ARM performance counters do not support "
 			 "mode exclusion\n");
 		return -EOPNOTSUPP;
 	}

 	/*
 	 * Store the event encoding into the config_base field.
 	 */
 	hwc->config_base	    |= (unsigned long)mapping;

 	if (!hwc->sample_period) {
 		/*
 		 * For non-sampling runs, limit the sample_period to half
 		 * of the counter width. That way, the new counter value
 		 * is far less likely to overtake the previous one unless
 		 * you have some serious IRQ latency issues.
 		 */
 		hwc->sample_period  = armpmu->max_period >> 1;
 		hwc->last_period    = hwc->sample_period;
 		local64_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 armpmu_event_init(struct perf_event *event)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
 	int err = 0;
 	atomic_t *active_events = &armpmu->active_events;

 	/* does not support taken branch sampling */
 	if (has_branch_stack(event))
 		return -EOPNOTSUPP;

 	if (armpmu->map_event(event) == -ENOENT)
 		return -ENOENT;

 	event->destroy = hw_perf_event_destroy;

 	if (!atomic_inc_not_zero(active_events)) {
 		mutex_lock(&armpmu->reserve_mutex);
 		if (atomic_read(active_events) == 0)
 			err = armpmu_reserve_hardware(armpmu);

 		if (!err)
 			atomic_inc(active_events);
 		mutex_unlock(&armpmu->reserve_mutex);
 	}

 	if (err)
 		return err;

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

 	return err;
 }

 static void armpmu_enable(struct pmu *pmu)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(pmu);
 	struct pmu_hw_events *hw_events = armpmu->get_hw_events();
 	int enabled = bitmap_weight(hw_events->used_mask, armpmu->num_events);

 	if (enabled)
 		armpmu->start(armpmu);
 }

 static void armpmu_disable(struct pmu *pmu)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(pmu);
 	armpmu->stop(armpmu);
 }

 #ifdef CONFIG_PM_RUNTIME
 static int armpmu_runtime_resume(struct device *dev)
 {
 	struct arm_pmu_platdata *plat = dev_get_platdata(dev);

 	if (plat && plat->runtime_resume)
 		return plat->runtime_resume(dev);

 	return 0;
 }

 static int armpmu_runtime_suspend(struct device *dev)
 {
 	struct arm_pmu_platdata *plat = dev_get_platdata(dev);

 	if (plat && plat->runtime_suspend)
 		return plat->runtime_suspend(dev);

 	return 0;
 }
 #endif

 const struct dev_pm_ops armpmu_dev_pm_ops = {
 	SET_RUNTIME_PM_OPS(armpmu_runtime_suspend, armpmu_runtime_resume, NULL)
 };

 static void __init armpmu_init(struct arm_pmu *armpmu)
 {
 	atomic_set(&armpmu->active_events, 0);
 	mutex_init(&armpmu->reserve_mutex);

 	armpmu->pmu = (struct pmu) {
 		.pmu_enable	= armpmu_enable,
 		.pmu_disable	= armpmu_disable,
 		.event_init	= armpmu_event_init,
 		.add		= armpmu_add,
 		.del		= armpmu_del,
 		.start		= armpmu_start,
 		.stop		= armpmu_stop,
 		.read		= armpmu_read,
 	};
 }

 int armpmu_register(struct arm_pmu *armpmu, int type)
 {
 	armpmu_init(armpmu);
 	pm_runtime_enable(&armpmu->plat_device->dev);
 	pr_info("enabled with %s PMU driver, %d counters available\n",
 			armpmu->name, armpmu->num_events);
 	return perf_pmu_register(&armpmu->pmu, armpmu->name, type);
 }

 /*
  * Callchain handling code.
  */

 /*
  * 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 __user *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 *
 user_backtrace(struct frame_tail __user *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;

 	perf_callchain_store(entry, buftail.lr);

 	/*
 	 * Frame pointers should strictly progress back up the stack
 	 * (towards higher addresses).
 	 */
 	if (tail + 1 >= buftail.fp)
 		return NULL;

 	return buftail.fp - 1;
 }

 void
 perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
 {
 	struct frame_tail __user *tail;

 	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}

 	tail = (struct frame_tail __user *)regs->ARM_fp - 1;

 	while ((entry->nr < PERF_MAX_STACK_DEPTH) &&
 	       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;
 	perf_callchain_store(entry, fr->pc);
 	return 0;
 }

 void
 perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
 {
 	struct stackframe fr;

 	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}

 	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);
 }

 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
 	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
 		return perf_guest_cbs->get_guest_ip();

 	return instruction_pointer(regs);
 }

 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
 	int misc = 0;

 	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
 		if (perf_guest_cbs->is_user_mode())
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
 	} else {
 		if (user_mode(regs))
 			misc |= PERF_RECORD_MISC_USER;
 		else
 			misc |= PERF_RECORD_MISC_KERNEL;
 	}

 	return misc;
 }
	#undef DEBUG

	/*
	* ARM performance counter support.
	*
	* Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
	* Copyright (C) 2010 ARM Ltd., Will Deacon <will.deacon@arm.com>
	*
	* 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/kernel.h>
	#include <linux/platform_device.h>
	#include <linux/pm_runtime.h>
	#include <linux/uaccess.h>

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

	static int
	armpmu_map_cache_event(const unsigned (*cache_map)
	[PERF_COUNT_HW_CACHE_MAX]
	[PERF_COUNT_HW_CACHE_OP_MAX]
	[PERF_COUNT_HW_CACHE_RESULT_MAX],
	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)(*cache_map)[cache_type][cache_op][cache_result];

	if (ret == CACHE_OP_UNSUPPORTED)
	return -ENOENT;

	return ret;
	}

	static int
	armpmu_map_hw_event(const unsigned (*event_map)[PERF_COUNT_HW_MAX], u64 config)
	{
	int mapping = (*event_map)[config];
	return mapping == HW_OP_UNSUPPORTED ? -ENOENT : mapping;
	}

	static int
	armpmu_map_raw_event(u32 raw_event_mask, u64 config)
	{
	return (int)(config & raw_event_mask);
	}

	int
	armpmu_map_event(struct perf_event *event,
	const unsigned (*event_map)[PERF_COUNT_HW_MAX],
	const unsigned (*cache_map)
	[PERF_COUNT_HW_CACHE_MAX]
	[PERF_COUNT_HW_CACHE_OP_MAX]
	[PERF_COUNT_HW_CACHE_RESULT_MAX],
	u32 raw_event_mask)
	{
	u64 config = event->attr.config;

	switch (event->attr.type) {
	case PERF_TYPE_HARDWARE:
	return armpmu_map_hw_event(event_map, config);
	case PERF_TYPE_HW_CACHE:
	return armpmu_map_cache_event(cache_map, config);
	case PERF_TYPE_RAW:
	return armpmu_map_raw_event(raw_event_mask, config);
	}

	return -ENOENT;
	}

	int armpmu_event_set_period(struct perf_event *event)
	{
	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
	struct hw_perf_event *hwc = &event->hw;
	s64 left = local64_read(&hwc->period_left);
	s64 period = hwc->sample_period;
	int ret = 0;

	/* The period may have been changed by PERF_EVENT_IOC_PERIOD */
	if (unlikely(period != hwc->last_period))
	left = period - (hwc->last_period - left);

	if (unlikely(left <= -period)) {
	left = period;
	local64_set(&hwc->period_left, left);
	hwc->last_period = period;
	ret = 1;
	}

	if (unlikely(left <= 0)) {
	left += period;
	local64_set(&hwc->period_left, left);
	hwc->last_period = period;
	ret = 1;
	}

	if (left > (s64)armpmu->max_period)
	left = armpmu->max_period;

	local64_set(&hwc->prev_count, (u64)-left);

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

	perf_event_update_userpage(event);

	return ret;
	}

	u64 armpmu_event_update(struct perf_event *event)
	{
	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
	struct hw_perf_event *hwc = &event->hw;
	u64 delta, prev_raw_count, new_raw_count;

	again:
	prev_raw_count = local64_read(&hwc->prev_count);
	new_raw_count = armpmu->read_counter(event);

	if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
	new_raw_count) != prev_raw_count)
	goto again;

	delta = (new_raw_count - prev_raw_count) & armpmu->max_period;

	local64_add(delta, &event->count);
	local64_sub(delta, &hwc->period_left);

	return new_raw_count;
	}

	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);
	}

	static void
	armpmu_stop(struct perf_event *event, int flags)
	{
	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
	struct hw_perf_event *hwc = &event->hw;

	/*
	* ARM pmu always has to update the counter, so ignore
	* PERF_EF_UPDATE, see comments in armpmu_start().
	*/
	if (!(hwc->state & PERF_HES_STOPPED)) {
	armpmu->disable(event);
	armpmu_event_update(event);
	hwc->state \|= PERF_HES_STOPPED \| PERF_HES_UPTODATE;
	}
	}

	static void armpmu_start(struct perf_event *event, int flags)
	{
	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
	struct hw_perf_event *hwc = &event->hw;

	/*
	* ARM pmu always has to reprogram the period, so ignore
	* PERF_EF_RELOAD, see the comment below.
	*/
	if (flags & PERF_EF_RELOAD)
	WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));

	hwc->state = 0;
	/*
	* Set the period again. Some counters can't be stopped, so when we
	* were stopped 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);
	armpmu->enable(event);
	}

	static void
	armpmu_del(struct perf_event *event, int flags)
	{
	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
	struct pmu_hw_events *hw_events = armpmu->get_hw_events();
	struct hw_perf_event *hwc = &event->hw;
	int idx = hwc->idx;

	WARN_ON(idx < 0);

	armpmu_stop(event, PERF_EF_UPDATE);
	hw_events->events[idx] = NULL;
	clear_bit(idx, hw_events->used_mask);

	perf_event_update_userpage(event);
	}

	static int
	armpmu_add(struct perf_event *event, int flags)
	{
	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
	struct pmu_hw_events *hw_events = armpmu->get_hw_events();
	struct hw_perf_event *hwc = &event->hw;
	int idx;
	int err = 0;

	perf_pmu_disable(event->pmu);

	/* If we don't have a space for the counter then finish early. */
	idx = armpmu->get_event_idx(hw_events, event);
	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(event);
	hw_events->events[idx] = event;

	hwc->state = PERF_HES_STOPPED \| PERF_HES_UPTODATE;
	if (flags & PERF_EF_START)
	armpmu_start(event, PERF_EF_RELOAD);

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

	out:
	perf_pmu_enable(event->pmu);
	return err;
	}

	static int
	validate_event(struct pmu_hw_events *hw_events,
	struct perf_event *event)
	{
	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
	struct pmu *leader_pmu = event->group_leader->pmu;

	if (event->pmu != leader_pmu \|\| event->state <= PERF_EVENT_STATE_OFF)
	return 1;

	return armpmu->get_event_idx(hw_events, event) >= 0;
	}

	static int
	validate_group(struct perf_event *event)
	{
	struct perf_event sibling, leader = event->group_leader;
	struct pmu_hw_events fake_pmu;
	DECLARE_BITMAP(fake_used_mask, ARMPMU_MAX_HWEVENTS);

	/*
	* Initialise the fake PMU. We only need to populate the
	* used_mask for the purposes of validation.
	*/
	memset(fake_used_mask, 0, sizeof(fake_used_mask));
	fake_pmu.used_mask = fake_used_mask;

	if (!validate_event(&fake_pmu, leader))
	return -EINVAL;

	list_for_each_entry(sibling, &leader->sibling_list, group_entry) {
	if (!validate_event(&fake_pmu, sibling))
	return -EINVAL;
	}

	if (!validate_event(&fake_pmu, event))
	return -EINVAL;

	return 0;
	}

	static irqreturn_t armpmu_dispatch_irq(int irq, void *dev)
	{
	struct arm_pmu armpmu = (struct arm_pmu ) dev;
	struct platform_device *plat_device = armpmu->plat_device;
	struct arm_pmu_platdata *plat = dev_get_platdata(&plat_device->dev);

	if (plat && plat->handle_irq)
	return plat->handle_irq(irq, dev, armpmu->handle_irq);
	else
	return armpmu->handle_irq(irq, dev);
	}

	static void
	armpmu_release_hardware(struct arm_pmu *armpmu)
	{
	armpmu->free_irq(armpmu);
	pm_runtime_put_sync(&armpmu->plat_device->dev);
	}

	static int
	armpmu_reserve_hardware(struct arm_pmu *armpmu)
	{
	int err;
	struct platform_device *pmu_device = armpmu->plat_device;

	if (!pmu_device)
	return -ENODEV;

	pm_runtime_get_sync(&pmu_device->dev);
	err = armpmu->request_irq(armpmu, armpmu_dispatch_irq);
	if (err) {
	armpmu_release_hardware(armpmu);
	return err;
	}

	return 0;
	}

	static void
	hw_perf_event_destroy(struct perf_event *event)
	{
	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
	atomic_t *active_events = &armpmu->active_events;
	struct mutex *pmu_reserve_mutex = &armpmu->reserve_mutex;

	if (atomic_dec_and_mutex_lock(active_events, pmu_reserve_mutex)) {
	armpmu_release_hardware(armpmu);
	mutex_unlock(pmu_reserve_mutex);
	}
	}

	static int
	event_requires_mode_exclusion(struct perf_event_attr *attr)
	{
	return attr->exclude_idle \|\| attr->exclude_user \|\|
	attr->exclude_kernel \|\| attr->exclude_hv;
	}

	static int
	__hw_perf_event_init(struct perf_event *event)
	{
	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
	struct hw_perf_event *hwc = &event->hw;
	int mapping, err;

	mapping = armpmu->map_event(event);

	if (mapping < 0) {
	pr_debug("event %x:%llx not supported\n", event->attr.type,
	event->attr.config);
	return mapping;
	}

	/*
	* 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;
	hwc->config_base = 0;
	hwc->config = 0;
	hwc->event_base = 0;

	/*
	* Check whether we need to exclude the counter from certain modes.
	*/
	if ((!armpmu->set_event_filter \|\|
	armpmu->set_event_filter(hwc, &event->attr)) &&
	event_requires_mode_exclusion(&event->attr)) {
	pr_debug("ARM performance counters do not support "
	"mode exclusion\n");
	return -EOPNOTSUPP;
	}

	/*
	* Store the event encoding into the config_base field.
	*/
	hwc->config_base \|= (unsigned long)mapping;

	if (!hwc->sample_period) {
	/*
	* For non-sampling runs, limit the sample_period to half
	* of the counter width. That way, the new counter value
	* is far less likely to overtake the previous one unless
	* you have some serious IRQ latency issues.
	*/
	hwc->sample_period = armpmu->max_period >> 1;
	hwc->last_period = hwc->sample_period;
	local64_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 armpmu_event_init(struct perf_event *event)
	{
	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
	int err = 0;
	atomic_t *active_events = &armpmu->active_events;

	/* does not support taken branch sampling */
	if (has_branch_stack(event))
	return -EOPNOTSUPP;

	if (armpmu->map_event(event) == -ENOENT)
	return -ENOENT;

	event->destroy = hw_perf_event_destroy;

	if (!atomic_inc_not_zero(active_events)) {
	mutex_lock(&armpmu->reserve_mutex);
	if (atomic_read(active_events) == 0)
	err = armpmu_reserve_hardware(armpmu);

	if (!err)
	atomic_inc(active_events);
	mutex_unlock(&armpmu->reserve_mutex);
	}

	if (err)
	return err;

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

	return err;
	}

	static void armpmu_enable(struct pmu *pmu)
	{
	struct arm_pmu *armpmu = to_arm_pmu(pmu);
	struct pmu_hw_events *hw_events = armpmu->get_hw_events();
	int enabled = bitmap_weight(hw_events->used_mask, armpmu->num_events);

	if (enabled)
	armpmu->start(armpmu);
	}

	static void armpmu_disable(struct pmu *pmu)
	{
	struct arm_pmu *armpmu = to_arm_pmu(pmu);
	armpmu->stop(armpmu);
	}

	#ifdef CONFIG_PM_RUNTIME
	static int armpmu_runtime_resume(struct device *dev)
	{
	struct arm_pmu_platdata *plat = dev_get_platdata(dev);

	if (plat && plat->runtime_resume)
	return plat->runtime_resume(dev);

	return 0;
	}

	static int armpmu_runtime_suspend(struct device *dev)
	{
	struct arm_pmu_platdata *plat = dev_get_platdata(dev);

	if (plat && plat->runtime_suspend)
	return plat->runtime_suspend(dev);

	return 0;
	}
	#endif

	const struct dev_pm_ops armpmu_dev_pm_ops = {
	SET_RUNTIME_PM_OPS(armpmu_runtime_suspend, armpmu_runtime_resume, NULL)
	};

	static void __init armpmu_init(struct arm_pmu *armpmu)
	{
	atomic_set(&armpmu->active_events, 0);
	mutex_init(&armpmu->reserve_mutex);

	armpmu->pmu = (struct pmu) {
	.pmu_enable = armpmu_enable,
	.pmu_disable = armpmu_disable,
	.event_init = armpmu_event_init,
	.add = armpmu_add,
	.del = armpmu_del,
	.start = armpmu_start,
	.stop = armpmu_stop,
	.read = armpmu_read,
	};
	}

	int armpmu_register(struct arm_pmu *armpmu, int type)
	{
	armpmu_init(armpmu);
	pm_runtime_enable(&armpmu->plat_device->dev);
	pr_info("enabled with %s PMU driver, %d counters available\n",
	armpmu->name, armpmu->num_events);
	return perf_pmu_register(&armpmu->pmu, armpmu->name, type);
	}

	/*
	* Callchain handling code.
	*/

	/*
	* 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 __user *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 *
	user_backtrace(struct frame_tail __user *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;

	perf_callchain_store(entry, buftail.lr);

	/*
	* Frame pointers should strictly progress back up the stack
	* (towards higher addresses).
	*/
	if (tail + 1 >= buftail.fp)
	return NULL;

	return buftail.fp - 1;
	}

	void
	perf_callchain_user(struct perf_callchain_entry entry, struct pt_regs regs)
	{
	struct frame_tail __user *tail;

	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
	/* We don't support guest os callchain now */
	return;
	}

	tail = (struct frame_tail __user *)regs->ARM_fp - 1;

	while ((entry->nr < PERF_MAX_STACK_DEPTH) &&
	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;
	perf_callchain_store(entry, fr->pc);
	return 0;
	}

	void
	perf_callchain_kernel(struct perf_callchain_entry entry, struct pt_regs regs)
	{
	struct stackframe fr;

	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
	/* We don't support guest os callchain now */
	return;
	}

	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);
	}

	unsigned long perf_instruction_pointer(struct pt_regs *regs)
	{
	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
	return perf_guest_cbs->get_guest_ip();

	return instruction_pointer(regs);
	}

	unsigned long perf_misc_flags(struct pt_regs *regs)
	{
	int misc = 0;

	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
	if (perf_guest_cbs->is_user_mode())
	misc \|= PERF_RECORD_MISC_GUEST_USER;
	else
	misc \|= PERF_RECORD_MISC_GUEST_KERNEL;
	} else {
	if (user_mode(regs))
	misc \|= PERF_RECORD_MISC_USER;
	else
	misc \|= PERF_RECORD_MISC_KERNEL;
	}

	return misc;
	}