Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 898 insertions, 0 deletions

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
new file mode 100644
index 000000000..453fdfdc6
--- /dev/null
+++ b/drivers/perf/arm_pmu.c
@@ -0,0 +1,898 @@
+#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.
+ */
+#define pr_fmt(fmt) "hw perfevents: " fmt
+
+#include <linux/bitmap.h>
+#include <linux/cpumask.h>
+#include <linux/cpu_pm.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/perf/arm_pmu.h>
+#include <linux/slab.h>
+#include <linux/sched/clock.h>
+#include <linux/spinlock.h>
+#include <linux/irq.h>
+#include <linux/irqdesc.h>
+
+#include <asm/irq_regs.h>
+
+static DEFINE_PER_CPU(struct arm_pmu *, cpu_armpmu);
+static DEFINE_PER_CPU(int, cpu_irq);
+
+static inline u64 arm_pmu_event_max_period(struct perf_event *event)
+{
+	if (event->hw.flags & ARMPMU_EVT_64BIT)
+		return GENMASK_ULL(63, 0);
+	else
+		return GENMASK_ULL(31, 0);
+}
+
+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;
+
+	if (!cache_map)
+		return -ENOENT;
+
+	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;
+
+	if (config >= PERF_COUNT_HW_MAX)
+		return -EINVAL;
+
+	if (!event_map)
+		return -ENOENT;
+
+	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;
+	int type = event->attr.type;
+
+	if (type == event->pmu->type)
+		return armpmu_map_raw_event(raw_event_mask, config);
+
+	switch (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;
+	u64 max_period;
+	int ret = 0;
+
+	max_period = arm_pmu_event_max_period(event);
+	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;
+	}
+
+	/*
+	 * Limit the maximum period to prevent the counter value
+	 * from overtaking the one we are about to program. In
+	 * effect we are reducing max_period to account for
+	 * interrupt latency (and we are being very conservative).
+	 */
+	if (left > (max_period >> 1))
+		left = (max_period >> 1);
+
+	local64_set(&hwc->prev_count, (u64)-left);
+
+	armpmu->write_counter(event, (u64)(-left) & max_period);
+
+	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;
+	u64 max_period = arm_pmu_event_max_period(event);
+
+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) & 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)
+{
+	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 = this_cpu_ptr(armpmu->hw_events);
+	struct hw_perf_event *hwc = &event->hw;
+	int idx = hwc->idx;
+
+	armpmu_stop(event, PERF_EF_UPDATE);
+	hw_events->events[idx] = NULL;
+	armpmu->clear_event_idx(hw_events, event);
+	perf_event_update_userpage(event);
+	/* Clear the allocated counter */
+	hwc->idx = -1;
+}
+
+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 = this_cpu_ptr(armpmu->hw_events);
+	struct hw_perf_event *hwc = &event->hw;
+	int idx;
+
+	/* An event following a process won't be stopped earlier */
+	if (!cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus))
+		return -ENOENT;
+
+	/* If we don't have a space for the counter then finish early. */
+	idx = armpmu->get_event_idx(hw_events, event);
+	if (idx < 0)
+		return idx;
+
+	/*
+	 * 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);
+
+	return 0;
+}
+
+static int
+validate_event(struct pmu *pmu, struct pmu_hw_events *hw_events,
+			       struct perf_event *event)
+{
+	struct arm_pmu *armpmu;
+
+	if (is_software_event(event))
+		return 1;
+
+	/*
+	 * Reject groups spanning multiple HW PMUs (e.g. CPU + CCI). The
+	 * core perf code won't check that the pmu->ctx == leader->ctx
+	 * until after pmu->event_init(event).
+	 */
+	if (event->pmu != pmu)
+		return 0;
+
+	if (event->state < PERF_EVENT_STATE_OFF)
+		return 1;
+
+	if (event->state == PERF_EVENT_STATE_OFF && !event->attr.enable_on_exec)
+		return 1;
+
+	armpmu = to_arm_pmu(event->pmu);
+	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;
+
+	/*
+	 * Initialise the fake PMU. We only need to populate the
+	 * used_mask for the purposes of validation.
+	 */
+	memset(&fake_pmu.used_mask, 0, sizeof(fake_pmu.used_mask));
+
+	if (!validate_event(event->pmu, &fake_pmu, leader))
+		return -EINVAL;
+
+	if (event == leader)
+		return 0;
+
+	for_each_sibling_event(sibling, leader) {
+		if (!validate_event(event->pmu, &fake_pmu, sibling))
+			return -EINVAL;
+	}
+
+	if (!validate_event(event->pmu, &fake_pmu, event))
+		return -EINVAL;
+
+	return 0;
+}
+
+static irqreturn_t armpmu_dispatch_irq(int irq, void *dev)
+{
+	struct arm_pmu *armpmu;
+	int ret;
+	u64 start_clock, finish_clock;
+
+	/*
+	 * we request the IRQ with a (possibly percpu) struct arm_pmu**, but
+	 * the handlers expect a struct arm_pmu*. The percpu_irq framework will
+	 * do any necessary shifting, we just need to perform the first
+	 * dereference.
+	 */
+	armpmu = *(void **)dev;
+	if (WARN_ON_ONCE(!armpmu))
+		return IRQ_NONE;
+
+	start_clock = sched_clock();
+	ret = armpmu->handle_irq(armpmu);
+	finish_clock = sched_clock();
+
+	perf_sample_event_took(finish_clock - start_clock);
+	return ret;
+}
+
+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;
+
+	hwc->flags = 0;
+	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 (!is_sampling_event(event)) {
+		/*
+		 * 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  = arm_pmu_event_max_period(event) >> 1;
+		hwc->last_period    = hwc->sample_period;
+		local64_set(&hwc->period_left, hwc->sample_period);
+	}
+
+	return validate_group(event);
+}
+
+static int armpmu_event_init(struct perf_event *event)
+{
+	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
+
+	/*
+	 * Reject CPU-affine events for CPUs that are of a different class to
+	 * that which this PMU handles. Process-following events (where
+	 * event->cpu == -1) can be migrated between CPUs, and thus we have to
+	 * reject them later (in armpmu_add) if they're scheduled on a
+	 * different class of CPU.
+	 */
+	if (event->cpu != -1 &&
+		!cpumask_test_cpu(event->cpu, &armpmu->supported_cpus))
+		return -ENOENT;
+
+	/* does not support taken branch sampling */
+	if (has_branch_stack(event))
+		return -EOPNOTSUPP;
+
+	if (armpmu->map_event(event) == -ENOENT)
+		return -ENOENT;
+
+	return __hw_perf_event_init(event);
+}
+
+static void armpmu_enable(struct pmu *pmu)
+{
+	struct arm_pmu *armpmu = to_arm_pmu(pmu);
+	struct pmu_hw_events *hw_events = this_cpu_ptr(armpmu->hw_events);
+	int enabled = bitmap_weight(hw_events->used_mask, armpmu->num_events);
+
+	/* For task-bound events we may be called on other CPUs */
+	if (!cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus))
+		return;
+
+	if (enabled)
+		armpmu->start(armpmu);
+}
+
+static void armpmu_disable(struct pmu *pmu)
+{
+	struct arm_pmu *armpmu = to_arm_pmu(pmu);
+
+	/* For task-bound events we may be called on other CPUs */
+	if (!cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus))
+		return;
+
+	armpmu->stop(armpmu);
+}
+
+/*
+ * In heterogeneous systems, events are specific to a particular
+ * microarchitecture, and aren't suitable for another. Thus, only match CPUs of
+ * the same microarchitecture.
+ */
+static int armpmu_filter_match(struct perf_event *event)
+{
+	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
+	unsigned int cpu = smp_processor_id();
+	int ret;
+
+	ret = cpumask_test_cpu(cpu, &armpmu->supported_cpus);
+	if (ret && armpmu->filter_match)
+		return armpmu->filter_match(event);
+
+	return ret;
+}
+
+static ssize_t armpmu_cpumask_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct arm_pmu *armpmu = to_arm_pmu(dev_get_drvdata(dev));
+	return cpumap_print_to_pagebuf(true, buf, &armpmu->supported_cpus);
+}
+
+static DEVICE_ATTR(cpus, S_IRUGO, armpmu_cpumask_show, NULL);
+
+static struct attribute *armpmu_common_attrs[] = {
+	&dev_attr_cpus.attr,
+	NULL,
+};
+
+static struct attribute_group armpmu_common_attr_group = {
+	.attrs = armpmu_common_attrs,
+};
+
+/* Set at runtime when we know what CPU type we are. */
+static struct arm_pmu *__oprofile_cpu_pmu;
+
+/*
+ * Despite the names, these two functions are CPU-specific and are used
+ * by the OProfile/perf code.
+ */
+const char *perf_pmu_name(void)
+{
+	if (!__oprofile_cpu_pmu)
+		return NULL;
+
+	return __oprofile_cpu_pmu->name;
+}
+EXPORT_SYMBOL_GPL(perf_pmu_name);
+
+int perf_num_counters(void)
+{
+	int max_events = 0;
+
+	if (__oprofile_cpu_pmu != NULL)
+		max_events = __oprofile_cpu_pmu->num_events;
+
+	return max_events;
+}
+EXPORT_SYMBOL_GPL(perf_num_counters);
+
+static int armpmu_count_irq_users(const int irq)
+{
+	int cpu, count = 0;
+
+	for_each_possible_cpu(cpu) {
+		if (per_cpu(cpu_irq, cpu) == irq)
+			count++;
+	}
+
+	return count;
+}
+
+void armpmu_free_irq(int irq, int cpu)
+{
+	if (per_cpu(cpu_irq, cpu) == 0)
+		return;
+	if (WARN_ON(irq != per_cpu(cpu_irq, cpu)))
+		return;
+
+	if (!irq_is_percpu_devid(irq))
+		free_irq(irq, per_cpu_ptr(&cpu_armpmu, cpu));
+	else if (armpmu_count_irq_users(irq) == 1)
+		free_percpu_irq(irq, &cpu_armpmu);
+
+	per_cpu(cpu_irq, cpu) = 0;
+}
+
+int armpmu_request_irq(int irq, int cpu)
+{
+	int err = 0;
+	const irq_handler_t handler = armpmu_dispatch_irq;
+	if (!irq)
+		return 0;
+
+	if (!irq_is_percpu_devid(irq)) {
+		unsigned long irq_flags;
+
+		err = irq_force_affinity(irq, cpumask_of(cpu));
+
+		if (err && num_possible_cpus() > 1) {
+			pr_warn("unable to set irq affinity (irq=%d, cpu=%u)\n",
+				irq, cpu);
+			goto err_out;
+		}
+
+		irq_flags = IRQF_PERCPU |
+			    IRQF_NOBALANCING |
+			    IRQF_NO_THREAD;
+
+		irq_set_status_flags(irq, IRQ_NOAUTOEN);
+		err = request_irq(irq, handler, irq_flags, "arm-pmu",
+				  per_cpu_ptr(&cpu_armpmu, cpu));
+	} else if (armpmu_count_irq_users(irq) == 0) {
+		err = request_percpu_irq(irq, handler, "arm-pmu",
+					 &cpu_armpmu);
+	}
+
+	if (err)
+		goto err_out;
+
+	per_cpu(cpu_irq, cpu) = irq;
+	return 0;
+
+err_out:
+	pr_err("unable to request IRQ%d for ARM PMU counters\n", irq);
+	return err;
+}
+
+static int armpmu_get_cpu_irq(struct arm_pmu *pmu, int cpu)
+{
+	struct pmu_hw_events __percpu *hw_events = pmu->hw_events;
+	return per_cpu(hw_events->irq, cpu);
+}
+
+/*
+ * PMU hardware loses all context when a CPU goes offline.
+ * When a CPU is hotplugged back in, since some hardware registers are
+ * UNKNOWN at reset, the PMU must be explicitly reset to avoid reading
+ * junk values out of them.
+ */
+static int arm_perf_starting_cpu(unsigned int cpu, struct hlist_node *node)
+{
+	struct arm_pmu *pmu = hlist_entry_safe(node, struct arm_pmu, node);
+	int irq;
+
+	if (!cpumask_test_cpu(cpu, &pmu->supported_cpus))
+		return 0;
+	if (pmu->reset)
+		pmu->reset(pmu);
+
+	per_cpu(cpu_armpmu, cpu) = pmu;
+
+	irq = armpmu_get_cpu_irq(pmu, cpu);
+	if (irq) {
+		if (irq_is_percpu_devid(irq))
+			enable_percpu_irq(irq, IRQ_TYPE_NONE);
+		else
+			enable_irq(irq);
+	}
+
+	return 0;
+}
+
+static int arm_perf_teardown_cpu(unsigned int cpu, struct hlist_node *node)
+{
+	struct arm_pmu *pmu = hlist_entry_safe(node, struct arm_pmu, node);
+	int irq;
+
+	if (!cpumask_test_cpu(cpu, &pmu->supported_cpus))
+		return 0;
+
+	irq = armpmu_get_cpu_irq(pmu, cpu);
+	if (irq) {
+		if (irq_is_percpu_devid(irq))
+			disable_percpu_irq(irq);
+		else
+			disable_irq_nosync(irq);
+	}
+
+	per_cpu(cpu_armpmu, cpu) = NULL;
+
+	return 0;
+}
+
+#ifdef CONFIG_CPU_PM
+static void cpu_pm_pmu_setup(struct arm_pmu *armpmu, unsigned long cmd)
+{
+	struct pmu_hw_events *hw_events = this_cpu_ptr(armpmu->hw_events);
+	struct perf_event *event;
+	int idx;
+
+	for (idx = 0; idx < armpmu->num_events; idx++) {
+		event = hw_events->events[idx];
+		if (!event)
+			continue;
+
+		switch (cmd) {
+		case CPU_PM_ENTER:
+			/*
+			 * Stop and update the counter
+			 */
+			armpmu_stop(event, PERF_EF_UPDATE);
+			break;
+		case CPU_PM_EXIT:
+		case CPU_PM_ENTER_FAILED:
+			 /*
+			  * Restore and enable the counter.
+			  * armpmu_start() indirectly calls
+			  *
+			  * perf_event_update_userpage()
+			  *
+			  * that requires RCU read locking to be functional,
+			  * wrap the call within RCU_NONIDLE to make the
+			  * RCU subsystem aware this cpu is not idle from
+			  * an RCU perspective for the armpmu_start() call
+			  * duration.
+			  */
+			RCU_NONIDLE(armpmu_start(event, PERF_EF_RELOAD));
+			break;
+		default:
+			break;
+		}
+	}
+}
+
+static int cpu_pm_pmu_notify(struct notifier_block *b, unsigned long cmd,
+			     void *v)
+{
+	struct arm_pmu *armpmu = container_of(b, struct arm_pmu, cpu_pm_nb);
+	struct pmu_hw_events *hw_events = this_cpu_ptr(armpmu->hw_events);
+	int enabled = bitmap_weight(hw_events->used_mask, armpmu->num_events);
+
+	if (!cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus))
+		return NOTIFY_DONE;
+
+	/*
+	 * Always reset the PMU registers on power-up even if
+	 * there are no events running.
+	 */
+	if (cmd == CPU_PM_EXIT && armpmu->reset)
+		armpmu->reset(armpmu);
+
+	if (!enabled)
+		return NOTIFY_OK;
+
+	switch (cmd) {
+	case CPU_PM_ENTER:
+		armpmu->stop(armpmu);
+		cpu_pm_pmu_setup(armpmu, cmd);
+		break;
+	case CPU_PM_EXIT:
+	case CPU_PM_ENTER_FAILED:
+		cpu_pm_pmu_setup(armpmu, cmd);
+		armpmu->start(armpmu);
+		break;
+	default:
+		return NOTIFY_DONE;
+	}
+
+	return NOTIFY_OK;
+}
+
+static int cpu_pm_pmu_register(struct arm_pmu *cpu_pmu)
+{
+	cpu_pmu->cpu_pm_nb.notifier_call = cpu_pm_pmu_notify;
+	return cpu_pm_register_notifier(&cpu_pmu->cpu_pm_nb);
+}
+
+static void cpu_pm_pmu_unregister(struct arm_pmu *cpu_pmu)
+{
+	cpu_pm_unregister_notifier(&cpu_pmu->cpu_pm_nb);
+}
+#else
+static inline int cpu_pm_pmu_register(struct arm_pmu *cpu_pmu) { return 0; }
+static inline void cpu_pm_pmu_unregister(struct arm_pmu *cpu_pmu) { }
+#endif
+
+static int cpu_pmu_init(struct arm_pmu *cpu_pmu)
+{
+	int err;
+
+	err = cpuhp_state_add_instance(CPUHP_AP_PERF_ARM_STARTING,
+				       &cpu_pmu->node);
+	if (err)
+		goto out;
+
+	err = cpu_pm_pmu_register(cpu_pmu);
+	if (err)
+		goto out_unregister;
+
+	return 0;
+
+out_unregister:
+	cpuhp_state_remove_instance_nocalls(CPUHP_AP_PERF_ARM_STARTING,
+					    &cpu_pmu->node);
+out:
+	return err;
+}
+
+static void cpu_pmu_destroy(struct arm_pmu *cpu_pmu)
+{
+	cpu_pm_pmu_unregister(cpu_pmu);
+	cpuhp_state_remove_instance_nocalls(CPUHP_AP_PERF_ARM_STARTING,
+					    &cpu_pmu->node);
+}
+
+static struct arm_pmu *__armpmu_alloc(gfp_t flags)
+{
+	struct arm_pmu *pmu;
+	int cpu;
+
+	pmu = kzalloc(sizeof(*pmu), flags);
+	if (!pmu) {
+		pr_info("failed to allocate PMU device!\n");
+		goto out;
+	}
+
+	pmu->hw_events = alloc_percpu_gfp(struct pmu_hw_events, flags);
+	if (!pmu->hw_events) {
+		pr_info("failed to allocate per-cpu PMU data.\n");
+		goto out_free_pmu;
+	}
+
+	pmu->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,
+		.filter_match	= armpmu_filter_match,
+		.attr_groups	= pmu->attr_groups,
+		/*
+		 * This is a CPU PMU potentially in a heterogeneous
+		 * configuration (e.g. big.LITTLE). This is not an uncore PMU,
+		 * and we have taken ctx sharing into account (e.g. with our
+		 * pmu::filter_match callback and pmu::event_init group
+		 * validation).
+		 */
+		.capabilities	= PERF_PMU_CAP_HETEROGENEOUS_CPUS,
+	};
+
+	pmu->attr_groups[ARMPMU_ATTR_GROUP_COMMON] =
+		&armpmu_common_attr_group;
+
+	for_each_possible_cpu(cpu) {
+		struct pmu_hw_events *events;
+
+		events = per_cpu_ptr(pmu->hw_events, cpu);
+		raw_spin_lock_init(&events->pmu_lock);
+		events->percpu_pmu = pmu;
+	}
+
+	return pmu;
+
+out_free_pmu:
+	kfree(pmu);
+out:
+	return NULL;
+}
+
+struct arm_pmu *armpmu_alloc(void)
+{
+	return __armpmu_alloc(GFP_KERNEL);
+}
+
+struct arm_pmu *armpmu_alloc_atomic(void)
+{
+	return __armpmu_alloc(GFP_ATOMIC);
+}
+
+
+void armpmu_free(struct arm_pmu *pmu)
+{
+	free_percpu(pmu->hw_events);
+	kfree(pmu);
+}
+
+int armpmu_register(struct arm_pmu *pmu)
+{
+	int ret;
+
+	ret = cpu_pmu_init(pmu);
+	if (ret)
+		return ret;
+
+	ret = perf_pmu_register(&pmu->pmu, pmu->name, -1);
+	if (ret)
+		goto out_destroy;
+
+	if (!__oprofile_cpu_pmu)
+		__oprofile_cpu_pmu = pmu;
+
+	pr_info("enabled with %s PMU driver, %d counters available\n",
+		pmu->name, pmu->num_events);
+
+	return 0;
+
+out_destroy:
+	cpu_pmu_destroy(pmu);
+	return ret;
+}
+
+static int arm_pmu_hp_init(void)
+{
+	int ret;
+
+	ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_STARTING,
+				      "perf/arm/pmu:starting",
+				      arm_perf_starting_cpu,
+				      arm_perf_teardown_cpu);
+	if (ret)
+		pr_err("CPU hotplug notifier for ARM PMU could not be registered: %d\n",
+		       ret);
+	return ret;
+}
+subsys_initcall(arm_pmu_hp_init);