Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 13761 insertions, 0 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
new file mode 100644
index 000000000..8c7d2f4f5
--- /dev/null
+++ b/kernel/events/core.c
@@ -0,0 +1,13761 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Performance events core code:
+ *
+ *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
+ *  Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
+ *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra
+ *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
+ */
+
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <linux/idr.h>
+#include <linux/file.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/hash.h>
+#include <linux/tick.h>
+#include <linux/sysfs.h>
+#include <linux/dcache.h>
+#include <linux/percpu.h>
+#include <linux/ptrace.h>
+#include <linux/reboot.h>
+#include <linux/vmstat.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/vmalloc.h>
+#include <linux/hardirq.h>
+#include <linux/hugetlb.h>
+#include <linux/rculist.h>
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/anon_inodes.h>
+#include <linux/kernel_stat.h>
+#include <linux/cgroup.h>
+#include <linux/perf_event.h>
+#include <linux/trace_events.h>
+#include <linux/hw_breakpoint.h>
+#include <linux/mm_types.h>
+#include <linux/module.h>
+#include <linux/mman.h>
+#include <linux/compat.h>
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <linux/namei.h>
+#include <linux/parser.h>
+#include <linux/sched/clock.h>
+#include <linux/sched/mm.h>
+#include <linux/proc_ns.h>
+#include <linux/mount.h>
+#include <linux/min_heap.h>
+#include <linux/highmem.h>
+#include <linux/pgtable.h>
+#include <linux/buildid.h>
+#include <linux/task_work.h>
+
+#include "internal.h"
+
+#include <asm/irq_regs.h>
+
+typedef int (*remote_function_f)(void *);
+
+struct remote_function_call {
+	struct task_struct	*p;
+	remote_function_f	func;
+	void			*info;
+	int			ret;
+};
+
+static void remote_function(void *data)
+{
+	struct remote_function_call *tfc = data;
+	struct task_struct *p = tfc->p;
+
+	if (p) {
+		/* -EAGAIN */
+		if (task_cpu(p) != smp_processor_id())
+			return;
+
+		/*
+		 * Now that we're on right CPU with IRQs disabled, we can test
+		 * if we hit the right task without races.
+		 */
+
+		tfc->ret = -ESRCH; /* No such (running) process */
+		if (p != current)
+			return;
+	}
+
+	tfc->ret = tfc->func(tfc->info);
+}
+
+/**
+ * task_function_call - call a function on the cpu on which a task runs
+ * @p:		the task to evaluate
+ * @func:	the function to be called
+ * @info:	the function call argument
+ *
+ * Calls the function @func when the task is currently running. This might
+ * be on the current CPU, which just calls the function directly.  This will
+ * retry due to any failures in smp_call_function_single(), such as if the
+ * task_cpu() goes offline concurrently.
+ *
+ * returns @func return value or -ESRCH or -ENXIO when the process isn't running
+ */
+static int
+task_function_call(struct task_struct *p, remote_function_f func, void *info)
+{
+	struct remote_function_call data = {
+		.p	= p,
+		.func	= func,
+		.info	= info,
+		.ret	= -EAGAIN,
+	};
+	int ret;
+
+	for (;;) {
+		ret = smp_call_function_single(task_cpu(p), remote_function,
+					       &data, 1);
+		if (!ret)
+			ret = data.ret;
+
+		if (ret != -EAGAIN)
+			break;
+
+		cond_resched();
+	}
+
+	return ret;
+}
+
+/**
+ * cpu_function_call - call a function on the cpu
+ * @cpu:	target cpu to queue this function
+ * @func:	the function to be called
+ * @info:	the function call argument
+ *
+ * Calls the function @func on the remote cpu.
+ *
+ * returns: @func return value or -ENXIO when the cpu is offline
+ */
+static int cpu_function_call(int cpu, remote_function_f func, void *info)
+{
+	struct remote_function_call data = {
+		.p	= NULL,
+		.func	= func,
+		.info	= info,
+		.ret	= -ENXIO, /* No such CPU */
+	};
+
+	smp_call_function_single(cpu, remote_function, &data, 1);
+
+	return data.ret;
+}
+
+static inline struct perf_cpu_context *
+__get_cpu_context(struct perf_event_context *ctx)
+{
+	return this_cpu_ptr(ctx->pmu->pmu_cpu_context);
+}
+
+static void perf_ctx_lock(struct perf_cpu_context *cpuctx,
+			  struct perf_event_context *ctx)
+{
+	raw_spin_lock(&cpuctx->ctx.lock);
+	if (ctx)
+		raw_spin_lock(&ctx->lock);
+}
+
+static void perf_ctx_unlock(struct perf_cpu_context *cpuctx,
+			    struct perf_event_context *ctx)
+{
+	if (ctx)
+		raw_spin_unlock(&ctx->lock);
+	raw_spin_unlock(&cpuctx->ctx.lock);
+}
+
+#define TASK_TOMBSTONE ((void *)-1L)
+
+static bool is_kernel_event(struct perf_event *event)
+{
+	return READ_ONCE(event->owner) == TASK_TOMBSTONE;
+}
+
+/*
+ * On task ctx scheduling...
+ *
+ * When !ctx->nr_events a task context will not be scheduled. This means
+ * we can disable the scheduler hooks (for performance) without leaving
+ * pending task ctx state.
+ *
+ * This however results in two special cases:
+ *
+ *  - removing the last event from a task ctx; this is relatively straight
+ *    forward and is done in __perf_remove_from_context.
+ *
+ *  - adding the first event to a task ctx; this is tricky because we cannot
+ *    rely on ctx->is_active and therefore cannot use event_function_call().
+ *    See perf_install_in_context().
+ *
+ * If ctx->nr_events, then ctx->is_active and cpuctx->task_ctx are set.
+ */
+
+typedef void (*event_f)(struct perf_event *, struct perf_cpu_context *,
+			struct perf_event_context *, void *);
+
+struct event_function_struct {
+	struct perf_event *event;
+	event_f func;
+	void *data;
+};
+
+static int event_function(void *info)
+{
+	struct event_function_struct *efs = info;
+	struct perf_event *event = efs->event;
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct perf_event_context *task_ctx = cpuctx->task_ctx;
+	int ret = 0;
+
+	lockdep_assert_irqs_disabled();
+
+	perf_ctx_lock(cpuctx, task_ctx);
+	/*
+	 * Since we do the IPI call without holding ctx->lock things can have
+	 * changed, double check we hit the task we set out to hit.
+	 */
+	if (ctx->task) {
+		if (ctx->task != current) {
+			ret = -ESRCH;
+			goto unlock;
+		}
+
+		/*
+		 * We only use event_function_call() on established contexts,
+		 * and event_function() is only ever called when active (or
+		 * rather, we'll have bailed in task_function_call() or the
+		 * above ctx->task != current test), therefore we must have
+		 * ctx->is_active here.
+		 */
+		WARN_ON_ONCE(!ctx->is_active);
+		/*
+		 * And since we have ctx->is_active, cpuctx->task_ctx must
+		 * match.
+		 */
+		WARN_ON_ONCE(task_ctx != ctx);
+	} else {
+		WARN_ON_ONCE(&cpuctx->ctx != ctx);
+	}
+
+	efs->func(event, cpuctx, ctx, efs->data);
+unlock:
+	perf_ctx_unlock(cpuctx, task_ctx);
+
+	return ret;
+}
+
+static void event_function_call(struct perf_event *event, event_f func, void *data)
+{
+	struct perf_event_context *ctx = event->ctx;
+	struct task_struct *task = READ_ONCE(ctx->task); /* verified in event_function */
+	struct event_function_struct efs = {
+		.event = event,
+		.func = func,
+		.data = data,
+	};
+
+	if (!event->parent) {
+		/*
+		 * If this is a !child event, we must hold ctx::mutex to
+		 * stabilize the event->ctx relation. See
+		 * perf_event_ctx_lock().
+		 */
+		lockdep_assert_held(&ctx->mutex);
+	}
+
+	if (!task) {
+		cpu_function_call(event->cpu, event_function, &efs);
+		return;
+	}
+
+	if (task == TASK_TOMBSTONE)
+		return;
+
+again:
+	if (!task_function_call(task, event_function, &efs))
+		return;
+
+	raw_spin_lock_irq(&ctx->lock);
+	/*
+	 * Reload the task pointer, it might have been changed by
+	 * a concurrent perf_event_context_sched_out().
+	 */
+	task = ctx->task;
+	if (task == TASK_TOMBSTONE) {
+		raw_spin_unlock_irq(&ctx->lock);
+		return;
+	}
+	if (ctx->is_active) {
+		raw_spin_unlock_irq(&ctx->lock);
+		goto again;
+	}
+	func(event, NULL, ctx, data);
+	raw_spin_unlock_irq(&ctx->lock);
+}
+
+/*
+ * Similar to event_function_call() + event_function(), but hard assumes IRQs
+ * are already disabled and we're on the right CPU.
+ */
+static void event_function_local(struct perf_event *event, event_f func, void *data)
+{
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct task_struct *task = READ_ONCE(ctx->task);
+	struct perf_event_context *task_ctx = NULL;
+
+	lockdep_assert_irqs_disabled();
+
+	if (task) {
+		if (task == TASK_TOMBSTONE)
+			return;
+
+		task_ctx = ctx;
+	}
+
+	perf_ctx_lock(cpuctx, task_ctx);
+
+	task = ctx->task;
+	if (task == TASK_TOMBSTONE)
+		goto unlock;
+
+	if (task) {
+		/*
+		 * We must be either inactive or active and the right task,
+		 * otherwise we're screwed, since we cannot IPI to somewhere
+		 * else.
+		 */
+		if (ctx->is_active) {
+			if (WARN_ON_ONCE(task != current))
+				goto unlock;
+
+			if (WARN_ON_ONCE(cpuctx->task_ctx != ctx))
+				goto unlock;
+		}
+	} else {
+		WARN_ON_ONCE(&cpuctx->ctx != ctx);
+	}
+
+	func(event, cpuctx, ctx, data);
+unlock:
+	perf_ctx_unlock(cpuctx, task_ctx);
+}
+
+#define PERF_FLAG_ALL (PERF_FLAG_FD_NO_GROUP |\
+		       PERF_FLAG_FD_OUTPUT  |\
+		       PERF_FLAG_PID_CGROUP |\
+		       PERF_FLAG_FD_CLOEXEC)
+
+/*
+ * branch priv levels that need permission checks
+ */
+#define PERF_SAMPLE_BRANCH_PERM_PLM \
+	(PERF_SAMPLE_BRANCH_KERNEL |\
+	 PERF_SAMPLE_BRANCH_HV)
+
+enum event_type_t {
+	EVENT_FLEXIBLE = 0x1,
+	EVENT_PINNED = 0x2,
+	EVENT_TIME = 0x4,
+	/* see ctx_resched() for details */
+	EVENT_CPU = 0x8,
+	EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
+};
+
+/*
+ * perf_sched_events : >0 events exist
+ * perf_cgroup_events: >0 per-cpu cgroup events exist on this cpu
+ */
+
+static void perf_sched_delayed(struct work_struct *work);
+DEFINE_STATIC_KEY_FALSE(perf_sched_events);
+static DECLARE_DELAYED_WORK(perf_sched_work, perf_sched_delayed);
+static DEFINE_MUTEX(perf_sched_mutex);
+static atomic_t perf_sched_count;
+
+static DEFINE_PER_CPU(atomic_t, perf_cgroup_events);
+static DEFINE_PER_CPU(int, perf_sched_cb_usages);
+static DEFINE_PER_CPU(struct pmu_event_list, pmu_sb_events);
+
+static atomic_t nr_mmap_events __read_mostly;
+static atomic_t nr_comm_events __read_mostly;
+static atomic_t nr_namespaces_events __read_mostly;
+static atomic_t nr_task_events __read_mostly;
+static atomic_t nr_freq_events __read_mostly;
+static atomic_t nr_switch_events __read_mostly;
+static atomic_t nr_ksymbol_events __read_mostly;
+static atomic_t nr_bpf_events __read_mostly;
+static atomic_t nr_cgroup_events __read_mostly;
+static atomic_t nr_text_poke_events __read_mostly;
+static atomic_t nr_build_id_events __read_mostly;
+
+static LIST_HEAD(pmus);
+static DEFINE_MUTEX(pmus_lock);
+static struct srcu_struct pmus_srcu;
+static cpumask_var_t perf_online_mask;
+static struct kmem_cache *perf_event_cache;
+
+/*
+ * perf event paranoia level:
+ *  -1 - not paranoid at all
+ *   0 - disallow raw tracepoint access for unpriv
+ *   1 - disallow cpu events for unpriv
+ *   2 - disallow kernel profiling for unpriv
+ */
+int sysctl_perf_event_paranoid __read_mostly = 2;
+
+/* Minimum for 512 kiB + 1 user control page */
+int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
+
+/*
+ * max perf event sample rate
+ */
+#define DEFAULT_MAX_SAMPLE_RATE		100000
+#define DEFAULT_SAMPLE_PERIOD_NS	(NSEC_PER_SEC / DEFAULT_MAX_SAMPLE_RATE)
+#define DEFAULT_CPU_TIME_MAX_PERCENT	25
+
+int sysctl_perf_event_sample_rate __read_mostly	= DEFAULT_MAX_SAMPLE_RATE;
+
+static int max_samples_per_tick __read_mostly	= DIV_ROUND_UP(DEFAULT_MAX_SAMPLE_RATE, HZ);
+static int perf_sample_period_ns __read_mostly	= DEFAULT_SAMPLE_PERIOD_NS;
+
+static int perf_sample_allowed_ns __read_mostly =
+	DEFAULT_SAMPLE_PERIOD_NS * DEFAULT_CPU_TIME_MAX_PERCENT / 100;
+
+static void update_perf_cpu_limits(void)
+{
+	u64 tmp = perf_sample_period_ns;
+
+	tmp *= sysctl_perf_cpu_time_max_percent;
+	tmp = div_u64(tmp, 100);
+	if (!tmp)
+		tmp = 1;
+
+	WRITE_ONCE(perf_sample_allowed_ns, tmp);
+}
+
+static bool perf_rotate_context(struct perf_cpu_context *cpuctx);
+
+int perf_proc_update_handler(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos)
+{
+	int ret;
+	int perf_cpu = sysctl_perf_cpu_time_max_percent;
+	/*
+	 * If throttling is disabled don't allow the write:
+	 */
+	if (write && (perf_cpu == 100 || perf_cpu == 0))
+		return -EINVAL;
+
+	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+	if (ret || !write)
+		return ret;
+
+	max_samples_per_tick = DIV_ROUND_UP(sysctl_perf_event_sample_rate, HZ);
+	perf_sample_period_ns = NSEC_PER_SEC / sysctl_perf_event_sample_rate;
+	update_perf_cpu_limits();
+
+	return 0;
+}
+
+int sysctl_perf_cpu_time_max_percent __read_mostly = DEFAULT_CPU_TIME_MAX_PERCENT;
+
+int perf_cpu_time_max_percent_handler(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos)
+{
+	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+
+	if (ret || !write)
+		return ret;
+
+	if (sysctl_perf_cpu_time_max_percent == 100 ||
+	    sysctl_perf_cpu_time_max_percent == 0) {
+		printk(KERN_WARNING
+		       "perf: Dynamic interrupt throttling disabled, can hang your system!\n");
+		WRITE_ONCE(perf_sample_allowed_ns, 0);
+	} else {
+		update_perf_cpu_limits();
+	}
+
+	return 0;
+}
+
+/*
+ * perf samples are done in some very critical code paths (NMIs).
+ * If they take too much CPU time, the system can lock up and not
+ * get any real work done.  This will drop the sample rate when
+ * we detect that events are taking too long.
+ */
+#define NR_ACCUMULATED_SAMPLES 128
+static DEFINE_PER_CPU(u64, running_sample_length);
+
+static u64 __report_avg;
+static u64 __report_allowed;
+
+static void perf_duration_warn(struct irq_work *w)
+{
+	printk_ratelimited(KERN_INFO
+		"perf: interrupt took too long (%lld > %lld), lowering "
+		"kernel.perf_event_max_sample_rate to %d\n",
+		__report_avg, __report_allowed,
+		sysctl_perf_event_sample_rate);
+}
+
+static DEFINE_IRQ_WORK(perf_duration_work, perf_duration_warn);
+
+void perf_sample_event_took(u64 sample_len_ns)
+{
+	u64 max_len = READ_ONCE(perf_sample_allowed_ns);
+	u64 running_len;
+	u64 avg_len;
+	u32 max;
+
+	if (max_len == 0)
+		return;
+
+	/* Decay the counter by 1 average sample. */
+	running_len = __this_cpu_read(running_sample_length);
+	running_len -= running_len/NR_ACCUMULATED_SAMPLES;
+	running_len += sample_len_ns;
+	__this_cpu_write(running_sample_length, running_len);
+
+	/*
+	 * Note: this will be biased artifically low until we have
+	 * seen NR_ACCUMULATED_SAMPLES. Doing it this way keeps us
+	 * from having to maintain a count.
+	 */
+	avg_len = running_len/NR_ACCUMULATED_SAMPLES;
+	if (avg_len <= max_len)
+		return;
+
+	__report_avg = avg_len;
+	__report_allowed = max_len;
+
+	/*
+	 * Compute a throttle threshold 25% below the current duration.
+	 */
+	avg_len += avg_len / 4;
+	max = (TICK_NSEC / 100) * sysctl_perf_cpu_time_max_percent;
+	if (avg_len < max)
+		max /= (u32)avg_len;
+	else
+		max = 1;
+
+	WRITE_ONCE(perf_sample_allowed_ns, avg_len);
+	WRITE_ONCE(max_samples_per_tick, max);
+
+	sysctl_perf_event_sample_rate = max * HZ;
+	perf_sample_period_ns = NSEC_PER_SEC / sysctl_perf_event_sample_rate;
+
+	if (!irq_work_queue(&perf_duration_work)) {
+		early_printk("perf: interrupt took too long (%lld > %lld), lowering "
+			     "kernel.perf_event_max_sample_rate to %d\n",
+			     __report_avg, __report_allowed,
+			     sysctl_perf_event_sample_rate);
+	}
+}
+
+static atomic64_t perf_event_id;
+
+static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
+			      enum event_type_t event_type);
+
+static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
+			     enum event_type_t event_type);
+
+static void update_context_time(struct perf_event_context *ctx);
+static u64 perf_event_time(struct perf_event *event);
+
+void __weak perf_event_print_debug(void)	{ }
+
+static inline u64 perf_clock(void)
+{
+	return local_clock();
+}
+
+static inline u64 perf_event_clock(struct perf_event *event)
+{
+	return event->clock();
+}
+
+/*
+ * State based event timekeeping...
+ *
+ * The basic idea is to use event->state to determine which (if any) time
+ * fields to increment with the current delta. This means we only need to
+ * update timestamps when we change state or when they are explicitly requested
+ * (read).
+ *
+ * Event groups make things a little more complicated, but not terribly so. The
+ * rules for a group are that if the group leader is OFF the entire group is
+ * OFF, irrespecive of what the group member states are. This results in
+ * __perf_effective_state().
+ *
+ * A futher ramification is that when a group leader flips between OFF and
+ * !OFF, we need to update all group member times.
+ *
+ *
+ * NOTE: perf_event_time() is based on the (cgroup) context time, and thus we
+ * need to make sure the relevant context time is updated before we try and
+ * update our timestamps.
+ */
+
+static __always_inline enum perf_event_state
+__perf_effective_state(struct perf_event *event)
+{
+	struct perf_event *leader = event->group_leader;
+
+	if (leader->state <= PERF_EVENT_STATE_OFF)
+		return leader->state;
+
+	return event->state;
+}
+
+static __always_inline void
+__perf_update_times(struct perf_event *event, u64 now, u64 *enabled, u64 *running)
+{
+	enum perf_event_state state = __perf_effective_state(event);
+	u64 delta = now - event->tstamp;
+
+	*enabled = event->total_time_enabled;
+	if (state >= PERF_EVENT_STATE_INACTIVE)
+		*enabled += delta;
+
+	*running = event->total_time_running;
+	if (state >= PERF_EVENT_STATE_ACTIVE)
+		*running += delta;
+}
+
+static void perf_event_update_time(struct perf_event *event)
+{
+	u64 now = perf_event_time(event);
+
+	__perf_update_times(event, now, &event->total_time_enabled,
+					&event->total_time_running);
+	event->tstamp = now;
+}
+
+static void perf_event_update_sibling_time(struct perf_event *leader)
+{
+	struct perf_event *sibling;
+
+	for_each_sibling_event(sibling, leader)
+		perf_event_update_time(sibling);
+}
+
+static void
+perf_event_set_state(struct perf_event *event, enum perf_event_state state)
+{
+	if (event->state == state)
+		return;
+
+	perf_event_update_time(event);
+	/*
+	 * If a group leader gets enabled/disabled all its siblings
+	 * are affected too.
+	 */
+	if ((event->state < 0) ^ (state < 0))
+		perf_event_update_sibling_time(event);
+
+	WRITE_ONCE(event->state, state);
+}
+
+/*
+ * UP store-release, load-acquire
+ */
+
+#define __store_release(ptr, val)					\
+do {									\
+	barrier();							\
+	WRITE_ONCE(*(ptr), (val));					\
+} while (0)
+
+#define __load_acquire(ptr)						\
+({									\
+	__unqual_scalar_typeof(*(ptr)) ___p = READ_ONCE(*(ptr));	\
+	barrier();							\
+	___p;								\
+})
+
+#ifdef CONFIG_CGROUP_PERF
+
+static inline bool
+perf_cgroup_match(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+
+	/* @event doesn't care about cgroup */
+	if (!event->cgrp)
+		return true;
+
+	/* wants specific cgroup scope but @cpuctx isn't associated with any */
+	if (!cpuctx->cgrp)
+		return false;
+
+	/*
+	 * Cgroup scoping is recursive.  An event enabled for a cgroup is
+	 * also enabled for all its descendant cgroups.  If @cpuctx's
+	 * cgroup is a descendant of @event's (the test covers identity
+	 * case), it's a match.
+	 */
+	return cgroup_is_descendant(cpuctx->cgrp->css.cgroup,
+				    event->cgrp->css.cgroup);
+}
+
+static inline void perf_detach_cgroup(struct perf_event *event)
+{
+	css_put(&event->cgrp->css);
+	event->cgrp = NULL;
+}
+
+static inline int is_cgroup_event(struct perf_event *event)
+{
+	return event->cgrp != NULL;
+}
+
+static inline u64 perf_cgroup_event_time(struct perf_event *event)
+{
+	struct perf_cgroup_info *t;
+
+	t = per_cpu_ptr(event->cgrp->info, event->cpu);
+	return t->time;
+}
+
+static inline u64 perf_cgroup_event_time_now(struct perf_event *event, u64 now)
+{
+	struct perf_cgroup_info *t;
+
+	t = per_cpu_ptr(event->cgrp->info, event->cpu);
+	if (!__load_acquire(&t->active))
+		return t->time;
+	now += READ_ONCE(t->timeoffset);
+	return now;
+}
+
+static inline void __update_cgrp_time(struct perf_cgroup_info *info, u64 now, bool adv)
+{
+	if (adv)
+		info->time += now - info->timestamp;
+	info->timestamp = now;
+	/*
+	 * see update_context_time()
+	 */
+	WRITE_ONCE(info->timeoffset, info->time - info->timestamp);
+}
+
+static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx, bool final)
+{
+	struct perf_cgroup *cgrp = cpuctx->cgrp;
+	struct cgroup_subsys_state *css;
+	struct perf_cgroup_info *info;
+
+	if (cgrp) {
+		u64 now = perf_clock();
+
+		for (css = &cgrp->css; css; css = css->parent) {
+			cgrp = container_of(css, struct perf_cgroup, css);
+			info = this_cpu_ptr(cgrp->info);
+
+			__update_cgrp_time(info, now, true);
+			if (final)
+				__store_release(&info->active, 0);
+		}
+	}
+}
+
+static inline void update_cgrp_time_from_event(struct perf_event *event)
+{
+	struct perf_cgroup_info *info;
+
+	/*
+	 * ensure we access cgroup data only when needed and
+	 * when we know the cgroup is pinned (css_get)
+	 */
+	if (!is_cgroup_event(event))
+		return;
+
+	info = this_cpu_ptr(event->cgrp->info);
+	/*
+	 * Do not update time when cgroup is not active
+	 */
+	if (info->active)
+		__update_cgrp_time(info, perf_clock(), true);
+}
+
+static inline void
+perf_cgroup_set_timestamp(struct perf_cpu_context *cpuctx)
+{
+	struct perf_event_context *ctx = &cpuctx->ctx;
+	struct perf_cgroup *cgrp = cpuctx->cgrp;
+	struct perf_cgroup_info *info;
+	struct cgroup_subsys_state *css;
+
+	/*
+	 * ctx->lock held by caller
+	 * ensure we do not access cgroup data
+	 * unless we have the cgroup pinned (css_get)
+	 */
+	if (!cgrp)
+		return;
+
+	WARN_ON_ONCE(!ctx->nr_cgroups);
+
+	for (css = &cgrp->css; css; css = css->parent) {
+		cgrp = container_of(css, struct perf_cgroup, css);
+		info = this_cpu_ptr(cgrp->info);
+		__update_cgrp_time(info, ctx->timestamp, false);
+		__store_release(&info->active, 1);
+	}
+}
+
+static DEFINE_PER_CPU(struct list_head, cgrp_cpuctx_list);
+
+/*
+ * reschedule events based on the cgroup constraint of task.
+ */
+static void perf_cgroup_switch(struct task_struct *task)
+{
+	struct perf_cgroup *cgrp;
+	struct perf_cpu_context *cpuctx, *tmp;
+	struct list_head *list;
+	unsigned long flags;
+
+	/*
+	 * Disable interrupts and preemption to avoid this CPU's
+	 * cgrp_cpuctx_entry to change under us.
+	 */
+	local_irq_save(flags);
+
+	cgrp = perf_cgroup_from_task(task, NULL);
+
+	list = this_cpu_ptr(&cgrp_cpuctx_list);
+	list_for_each_entry_safe(cpuctx, tmp, list, cgrp_cpuctx_entry) {
+		WARN_ON_ONCE(cpuctx->ctx.nr_cgroups == 0);
+		if (READ_ONCE(cpuctx->cgrp) == cgrp)
+			continue;
+
+		perf_ctx_lock(cpuctx, cpuctx->task_ctx);
+		perf_pmu_disable(cpuctx->ctx.pmu);
+
+		cpu_ctx_sched_out(cpuctx, EVENT_ALL);
+		/*
+		 * must not be done before ctxswout due
+		 * to update_cgrp_time_from_cpuctx() in
+		 * ctx_sched_out()
+		 */
+		cpuctx->cgrp = cgrp;
+		/*
+		 * set cgrp before ctxsw in to allow
+		 * perf_cgroup_set_timestamp() in ctx_sched_in()
+		 * to not have to pass task around
+		 */
+		cpu_ctx_sched_in(cpuctx, EVENT_ALL);
+
+		perf_pmu_enable(cpuctx->ctx.pmu);
+		perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
+	}
+
+	local_irq_restore(flags);
+}
+
+static int perf_cgroup_ensure_storage(struct perf_event *event,
+				struct cgroup_subsys_state *css)
+{
+	struct perf_cpu_context *cpuctx;
+	struct perf_event **storage;
+	int cpu, heap_size, ret = 0;
+
+	/*
+	 * Allow storage to have sufficent space for an iterator for each
+	 * possibly nested cgroup plus an iterator for events with no cgroup.
+	 */
+	for (heap_size = 1; css; css = css->parent)
+		heap_size++;
+
+	for_each_possible_cpu(cpu) {
+		cpuctx = per_cpu_ptr(event->pmu->pmu_cpu_context, cpu);
+		if (heap_size <= cpuctx->heap_size)
+			continue;
+
+		storage = kmalloc_node(heap_size * sizeof(struct perf_event *),
+				       GFP_KERNEL, cpu_to_node(cpu));
+		if (!storage) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		raw_spin_lock_irq(&cpuctx->ctx.lock);
+		if (cpuctx->heap_size < heap_size) {
+			swap(cpuctx->heap, storage);
+			if (storage == cpuctx->heap_default)
+				storage = NULL;
+			cpuctx->heap_size = heap_size;
+		}
+		raw_spin_unlock_irq(&cpuctx->ctx.lock);
+
+		kfree(storage);
+	}
+
+	return ret;
+}
+
+static inline int perf_cgroup_connect(int fd, struct perf_event *event,
+				      struct perf_event_attr *attr,
+				      struct perf_event *group_leader)
+{
+	struct perf_cgroup *cgrp;
+	struct cgroup_subsys_state *css;
+	struct fd f = fdget(fd);
+	int ret = 0;
+
+	if (!f.file)
+		return -EBADF;
+
+	css = css_tryget_online_from_dir(f.file->f_path.dentry,
+					 &perf_event_cgrp_subsys);
+	if (IS_ERR(css)) {
+		ret = PTR_ERR(css);
+		goto out;
+	}
+
+	ret = perf_cgroup_ensure_storage(event, css);
+	if (ret)
+		goto out;
+
+	cgrp = container_of(css, struct perf_cgroup, css);
+	event->cgrp = cgrp;
+
+	/*
+	 * all events in a group must monitor
+	 * the same cgroup because a task belongs
+	 * to only one perf cgroup at a time
+	 */
+	if (group_leader && group_leader->cgrp != cgrp) {
+		perf_detach_cgroup(event);
+		ret = -EINVAL;
+	}
+out:
+	fdput(f);
+	return ret;
+}
+
+static inline void
+perf_cgroup_event_enable(struct perf_event *event, struct perf_event_context *ctx)
+{
+	struct perf_cpu_context *cpuctx;
+
+	if (!is_cgroup_event(event))
+		return;
+
+	/*
+	 * Because cgroup events are always per-cpu events,
+	 * @ctx == &cpuctx->ctx.
+	 */
+	cpuctx = container_of(ctx, struct perf_cpu_context, ctx);
+
+	if (ctx->nr_cgroups++)
+		return;
+
+	cpuctx->cgrp = perf_cgroup_from_task(current, ctx);
+	list_add(&cpuctx->cgrp_cpuctx_entry,
+			per_cpu_ptr(&cgrp_cpuctx_list, event->cpu));
+}
+
+static inline void
+perf_cgroup_event_disable(struct perf_event *event, struct perf_event_context *ctx)
+{
+	struct perf_cpu_context *cpuctx;
+
+	if (!is_cgroup_event(event))
+		return;
+
+	/*
+	 * Because cgroup events are always per-cpu events,
+	 * @ctx == &cpuctx->ctx.
+	 */
+	cpuctx = container_of(ctx, struct perf_cpu_context, ctx);
+
+	if (--ctx->nr_cgroups)
+		return;
+
+	cpuctx->cgrp = NULL;
+	list_del(&cpuctx->cgrp_cpuctx_entry);
+}
+
+#else /* !CONFIG_CGROUP_PERF */
+
+static inline bool
+perf_cgroup_match(struct perf_event *event)
+{
+	return true;
+}
+
+static inline void perf_detach_cgroup(struct perf_event *event)
+{}
+
+static inline int is_cgroup_event(struct perf_event *event)
+{
+	return 0;
+}
+
+static inline void update_cgrp_time_from_event(struct perf_event *event)
+{
+}
+
+static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx,
+						bool final)
+{
+}
+
+static inline int perf_cgroup_connect(pid_t pid, struct perf_event *event,
+				      struct perf_event_attr *attr,
+				      struct perf_event *group_leader)
+{
+	return -EINVAL;
+}
+
+static inline void
+perf_cgroup_set_timestamp(struct perf_cpu_context *cpuctx)
+{
+}
+
+static inline u64 perf_cgroup_event_time(struct perf_event *event)
+{
+	return 0;
+}
+
+static inline u64 perf_cgroup_event_time_now(struct perf_event *event, u64 now)
+{
+	return 0;
+}
+
+static inline void
+perf_cgroup_event_enable(struct perf_event *event, struct perf_event_context *ctx)
+{
+}
+
+static inline void
+perf_cgroup_event_disable(struct perf_event *event, struct perf_event_context *ctx)
+{
+}
+
+static void perf_cgroup_switch(struct task_struct *task)
+{
+}
+#endif
+
+/*
+ * set default to be dependent on timer tick just
+ * like original code
+ */
+#define PERF_CPU_HRTIMER (1000 / HZ)
+/*
+ * function must be called with interrupts disabled
+ */
+static enum hrtimer_restart perf_mux_hrtimer_handler(struct hrtimer *hr)
+{
+	struct perf_cpu_context *cpuctx;
+	bool rotations;
+
+	lockdep_assert_irqs_disabled();
+
+	cpuctx = container_of(hr, struct perf_cpu_context, hrtimer);
+	rotations = perf_rotate_context(cpuctx);
+
+	raw_spin_lock(&cpuctx->hrtimer_lock);
+	if (rotations)
+		hrtimer_forward_now(hr, cpuctx->hrtimer_interval);
+	else
+		cpuctx->hrtimer_active = 0;
+	raw_spin_unlock(&cpuctx->hrtimer_lock);
+
+	return rotations ? HRTIMER_RESTART : HRTIMER_NORESTART;
+}
+
+static void __perf_mux_hrtimer_init(struct perf_cpu_context *cpuctx, int cpu)
+{
+	struct hrtimer *timer = &cpuctx->hrtimer;
+	struct pmu *pmu = cpuctx->ctx.pmu;
+	u64 interval;
+
+	/* no multiplexing needed for SW PMU */
+	if (pmu->task_ctx_nr == perf_sw_context)
+		return;
+
+	/*
+	 * check default is sane, if not set then force to
+	 * default interval (1/tick)
+	 */
+	interval = pmu->hrtimer_interval_ms;
+	if (interval < 1)
+		interval = pmu->hrtimer_interval_ms = PERF_CPU_HRTIMER;
+
+	cpuctx->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * interval);
+
+	raw_spin_lock_init(&cpuctx->hrtimer_lock);
+	hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
+	timer->function = perf_mux_hrtimer_handler;
+}
+
+static int perf_mux_hrtimer_restart(struct perf_cpu_context *cpuctx)
+{
+	struct hrtimer *timer = &cpuctx->hrtimer;
+	struct pmu *pmu = cpuctx->ctx.pmu;
+	unsigned long flags;
+
+	/* not for SW PMU */
+	if (pmu->task_ctx_nr == perf_sw_context)
+		return 0;
+
+	raw_spin_lock_irqsave(&cpuctx->hrtimer_lock, flags);
+	if (!cpuctx->hrtimer_active) {
+		cpuctx->hrtimer_active = 1;
+		hrtimer_forward_now(timer, cpuctx->hrtimer_interval);
+		hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED_HARD);
+	}
+	raw_spin_unlock_irqrestore(&cpuctx->hrtimer_lock, flags);
+
+	return 0;
+}
+
+static int perf_mux_hrtimer_restart_ipi(void *arg)
+{
+	return perf_mux_hrtimer_restart(arg);
+}
+
+void perf_pmu_disable(struct pmu *pmu)
+{
+	int *count = this_cpu_ptr(pmu->pmu_disable_count);
+	if (!(*count)++)
+		pmu->pmu_disable(pmu);
+}
+
+void perf_pmu_enable(struct pmu *pmu)
+{
+	int *count = this_cpu_ptr(pmu->pmu_disable_count);
+	if (!--(*count))
+		pmu->pmu_enable(pmu);
+}
+
+static DEFINE_PER_CPU(struct list_head, active_ctx_list);
+
+/*
+ * perf_event_ctx_activate(), perf_event_ctx_deactivate(), and
+ * perf_event_task_tick() are fully serialized because they're strictly cpu
+ * affine and perf_event_ctx{activate,deactivate} are called with IRQs
+ * disabled, while perf_event_task_tick is called from IRQ context.
+ */
+static void perf_event_ctx_activate(struct perf_event_context *ctx)
+{
+	struct list_head *head = this_cpu_ptr(&active_ctx_list);
+
+	lockdep_assert_irqs_disabled();
+
+	WARN_ON(!list_empty(&ctx->active_ctx_list));
+
+	list_add(&ctx->active_ctx_list, head);
+}
+
+static void perf_event_ctx_deactivate(struct perf_event_context *ctx)
+{
+	lockdep_assert_irqs_disabled();
+
+	WARN_ON(list_empty(&ctx->active_ctx_list));
+
+	list_del_init(&ctx->active_ctx_list);
+}
+
+static void get_ctx(struct perf_event_context *ctx)
+{
+	refcount_inc(&ctx->refcount);
+}
+
+static void *alloc_task_ctx_data(struct pmu *pmu)
+{
+	if (pmu->task_ctx_cache)
+		return kmem_cache_zalloc(pmu->task_ctx_cache, GFP_KERNEL);
+
+	return NULL;
+}
+
+static void free_task_ctx_data(struct pmu *pmu, void *task_ctx_data)
+{
+	if (pmu->task_ctx_cache && task_ctx_data)
+		kmem_cache_free(pmu->task_ctx_cache, task_ctx_data);
+}
+
+static void free_ctx(struct rcu_head *head)
+{
+	struct perf_event_context *ctx;
+
+	ctx = container_of(head, struct perf_event_context, rcu_head);
+	free_task_ctx_data(ctx->pmu, ctx->task_ctx_data);
+	kfree(ctx);
+}
+
+static void put_ctx(struct perf_event_context *ctx)
+{
+	if (refcount_dec_and_test(&ctx->refcount)) {
+		if (ctx->parent_ctx)
+			put_ctx(ctx->parent_ctx);
+		if (ctx->task && ctx->task != TASK_TOMBSTONE)
+			put_task_struct(ctx->task);
+		call_rcu(&ctx->rcu_head, free_ctx);
+	}
+}
+
+/*
+ * Because of perf_event::ctx migration in sys_perf_event_open::move_group and
+ * perf_pmu_migrate_context() we need some magic.
+ *
+ * Those places that change perf_event::ctx will hold both
+ * perf_event_ctx::mutex of the 'old' and 'new' ctx value.
+ *
+ * Lock ordering is by mutex address. There are two other sites where
+ * perf_event_context::mutex nests and those are:
+ *
+ *  - perf_event_exit_task_context()	[ child , 0 ]
+ *      perf_event_exit_event()
+ *        put_event()			[ parent, 1 ]
+ *
+ *  - perf_event_init_context()		[ parent, 0 ]
+ *      inherit_task_group()
+ *        inherit_group()
+ *          inherit_event()
+ *            perf_event_alloc()
+ *              perf_init_event()
+ *                perf_try_init_event()	[ child , 1 ]
+ *
+ * While it appears there is an obvious deadlock here -- the parent and child
+ * nesting levels are inverted between the two. This is in fact safe because
+ * life-time rules separate them. That is an exiting task cannot fork, and a
+ * spawning task cannot (yet) exit.
+ *
+ * But remember that these are parent<->child context relations, and
+ * migration does not affect children, therefore these two orderings should not
+ * interact.
+ *
+ * The change in perf_event::ctx does not affect children (as claimed above)
+ * because the sys_perf_event_open() case will install a new event and break
+ * the ctx parent<->child relation, and perf_pmu_migrate_context() is only
+ * concerned with cpuctx and that doesn't have children.
+ *
+ * The places that change perf_event::ctx will issue:
+ *
+ *   perf_remove_from_context();
+ *   synchronize_rcu();
+ *   perf_install_in_context();
+ *
+ * to affect the change. The remove_from_context() + synchronize_rcu() should
+ * quiesce the event, after which we can install it in the new location. This
+ * means that only external vectors (perf_fops, prctl) can perturb the event
+ * while in transit. Therefore all such accessors should also acquire
+ * perf_event_context::mutex to serialize against this.
+ *
+ * However; because event->ctx can change while we're waiting to acquire
+ * ctx->mutex we must be careful and use the below perf_event_ctx_lock()
+ * function.
+ *
+ * Lock order:
+ *    exec_update_lock
+ *	task_struct::perf_event_mutex
+ *	  perf_event_context::mutex
+ *	    perf_event::child_mutex;
+ *	      perf_event_context::lock
+ *	    perf_event::mmap_mutex
+ *	    mmap_lock
+ *	      perf_addr_filters_head::lock
+ *
+ *    cpu_hotplug_lock
+ *      pmus_lock
+ *	  cpuctx->mutex / perf_event_context::mutex
+ */
+static struct perf_event_context *
+perf_event_ctx_lock_nested(struct perf_event *event, int nesting)
+{
+	struct perf_event_context *ctx;
+
+again:
+	rcu_read_lock();
+	ctx = READ_ONCE(event->ctx);
+	if (!refcount_inc_not_zero(&ctx->refcount)) {
+		rcu_read_unlock();
+		goto again;
+	}
+	rcu_read_unlock();
+
+	mutex_lock_nested(&ctx->mutex, nesting);
+	if (event->ctx != ctx) {
+		mutex_unlock(&ctx->mutex);
+		put_ctx(ctx);
+		goto again;
+	}
+
+	return ctx;
+}
+
+static inline struct perf_event_context *
+perf_event_ctx_lock(struct perf_event *event)
+{
+	return perf_event_ctx_lock_nested(event, 0);
+}
+
+static void perf_event_ctx_unlock(struct perf_event *event,
+				  struct perf_event_context *ctx)
+{
+	mutex_unlock(&ctx->mutex);
+	put_ctx(ctx);
+}
+
+/*
+ * This must be done under the ctx->lock, such as to serialize against
+ * context_equiv(), therefore we cannot call put_ctx() since that might end up
+ * calling scheduler related locks and ctx->lock nests inside those.
+ */
+static __must_check struct perf_event_context *
+unclone_ctx(struct perf_event_context *ctx)
+{
+	struct perf_event_context *parent_ctx = ctx->parent_ctx;
+
+	lockdep_assert_held(&ctx->lock);
+
+	if (parent_ctx)
+		ctx->parent_ctx = NULL;
+	ctx->generation++;
+
+	return parent_ctx;
+}
+
+static u32 perf_event_pid_type(struct perf_event *event, struct task_struct *p,
+				enum pid_type type)
+{
+	u32 nr;
+	/*
+	 * only top level events have the pid namespace they were created in
+	 */
+	if (event->parent)
+		event = event->parent;
+
+	nr = __task_pid_nr_ns(p, type, event->ns);
+	/* avoid -1 if it is idle thread or runs in another ns */
+	if (!nr && !pid_alive(p))
+		nr = -1;
+	return nr;
+}
+
+static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
+{
+	return perf_event_pid_type(event, p, PIDTYPE_TGID);
+}
+
+static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
+{
+	return perf_event_pid_type(event, p, PIDTYPE_PID);
+}
+
+/*
+ * If we inherit events we want to return the parent event id
+ * to userspace.
+ */
+static u64 primary_event_id(struct perf_event *event)
+{
+	u64 id = event->id;
+
+	if (event->parent)
+		id = event->parent->id;
+
+	return id;
+}
+
+/*
+ * Get the perf_event_context for a task and lock it.
+ *
+ * This has to cope with the fact that until it is locked,
+ * the context could get moved to another task.
+ */
+static struct perf_event_context *
+perf_lock_task_context(struct task_struct *task, int ctxn, unsigned long *flags)
+{
+	struct perf_event_context *ctx;
+
+retry:
+	/*
+	 * One of the few rules of preemptible RCU is that one cannot do
+	 * rcu_read_unlock() while holding a scheduler (or nested) lock when
+	 * part of the read side critical section was irqs-enabled -- see
+	 * rcu_read_unlock_special().
+	 *
+	 * Since ctx->lock nests under rq->lock we must ensure the entire read
+	 * side critical section has interrupts disabled.
+	 */
+	local_irq_save(*flags);
+	rcu_read_lock();
+	ctx = rcu_dereference(task->perf_event_ctxp[ctxn]);
+	if (ctx) {
+		/*
+		 * If this context is a clone of another, it might
+		 * get swapped for another underneath us by
+		 * perf_event_task_sched_out, though the
+		 * rcu_read_lock() protects us from any context
+		 * getting freed.  Lock the context and check if it
+		 * got swapped before we could get the lock, and retry
+		 * if so.  If we locked the right context, then it
+		 * can't get swapped on us any more.
+		 */
+		raw_spin_lock(&ctx->lock);
+		if (ctx != rcu_dereference(task->perf_event_ctxp[ctxn])) {
+			raw_spin_unlock(&ctx->lock);
+			rcu_read_unlock();
+			local_irq_restore(*flags);
+			goto retry;
+		}
+
+		if (ctx->task == TASK_TOMBSTONE ||
+		    !refcount_inc_not_zero(&ctx->refcount)) {
+			raw_spin_unlock(&ctx->lock);
+			ctx = NULL;
+		} else {
+			WARN_ON_ONCE(ctx->task != task);
+		}
+	}
+	rcu_read_unlock();
+	if (!ctx)
+		local_irq_restore(*flags);
+	return ctx;
+}
+
+/*
+ * Get the context for a task and increment its pin_count so it
+ * can't get swapped to another task.  This also increments its
+ * reference count so that the context can't get freed.
+ */
+static struct perf_event_context *
+perf_pin_task_context(struct task_struct *task, int ctxn)
+{
+	struct perf_event_context *ctx;
+	unsigned long flags;
+
+	ctx = perf_lock_task_context(task, ctxn, &flags);
+	if (ctx) {
+		++ctx->pin_count;
+		raw_spin_unlock_irqrestore(&ctx->lock, flags);
+	}
+	return ctx;
+}
+
+static void perf_unpin_context(struct perf_event_context *ctx)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&ctx->lock, flags);
+	--ctx->pin_count;
+	raw_spin_unlock_irqrestore(&ctx->lock, flags);
+}
+
+/*
+ * Update the record of the current time in a context.
+ */
+static void __update_context_time(struct perf_event_context *ctx, bool adv)
+{
+	u64 now = perf_clock();
+
+	lockdep_assert_held(&ctx->lock);
+
+	if (adv)
+		ctx->time += now - ctx->timestamp;
+	ctx->timestamp = now;
+
+	/*
+	 * The above: time' = time + (now - timestamp), can be re-arranged
+	 * into: time` = now + (time - timestamp), which gives a single value
+	 * offset to compute future time without locks on.
+	 *
+	 * See perf_event_time_now(), which can be used from NMI context where
+	 * it's (obviously) not possible to acquire ctx->lock in order to read
+	 * both the above values in a consistent manner.
+	 */
+	WRITE_ONCE(ctx->timeoffset, ctx->time - ctx->timestamp);
+}
+
+static void update_context_time(struct perf_event_context *ctx)
+{
+	__update_context_time(ctx, true);
+}
+
+static u64 perf_event_time(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+
+	if (unlikely(!ctx))
+		return 0;
+
+	if (is_cgroup_event(event))
+		return perf_cgroup_event_time(event);
+
+	return ctx->time;
+}
+
+static u64 perf_event_time_now(struct perf_event *event, u64 now)
+{
+	struct perf_event_context *ctx = event->ctx;
+
+	if (unlikely(!ctx))
+		return 0;
+
+	if (is_cgroup_event(event))
+		return perf_cgroup_event_time_now(event, now);
+
+	if (!(__load_acquire(&ctx->is_active) & EVENT_TIME))
+		return ctx->time;
+
+	now += READ_ONCE(ctx->timeoffset);
+	return now;
+}
+
+static enum event_type_t get_event_type(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+	enum event_type_t event_type;
+
+	lockdep_assert_held(&ctx->lock);
+
+	/*
+	 * It's 'group type', really, because if our group leader is
+	 * pinned, so are we.
+	 */
+	if (event->group_leader != event)
+		event = event->group_leader;
+
+	event_type = event->attr.pinned ? EVENT_PINNED : EVENT_FLEXIBLE;
+	if (!ctx->task)
+		event_type |= EVENT_CPU;
+
+	return event_type;
+}
+
+/*
+ * Helper function to initialize event group nodes.
+ */
+static void init_event_group(struct perf_event *event)
+{
+	RB_CLEAR_NODE(&event->group_node);
+	event->group_index = 0;
+}
+
+/*
+ * Extract pinned or flexible groups from the context
+ * based on event attrs bits.
+ */
+static struct perf_event_groups *
+get_event_groups(struct perf_event *event, struct perf_event_context *ctx)
+{
+	if (event->attr.pinned)
+		return &ctx->pinned_groups;
+	else
+		return &ctx->flexible_groups;
+}
+
+/*
+ * Helper function to initializes perf_event_group trees.
+ */
+static void perf_event_groups_init(struct perf_event_groups *groups)
+{
+	groups->tree = RB_ROOT;
+	groups->index = 0;
+}
+
+static inline struct cgroup *event_cgroup(const struct perf_event *event)
+{
+	struct cgroup *cgroup = NULL;
+
+#ifdef CONFIG_CGROUP_PERF
+	if (event->cgrp)
+		cgroup = event->cgrp->css.cgroup;
+#endif
+
+	return cgroup;
+}
+
+/*
+ * Compare function for event groups;
+ *
+ * Implements complex key that first sorts by CPU and then by virtual index
+ * which provides ordering when rotating groups for the same CPU.
+ */
+static __always_inline int
+perf_event_groups_cmp(const int left_cpu, const struct cgroup *left_cgroup,
+		      const u64 left_group_index, const struct perf_event *right)
+{
+	if (left_cpu < right->cpu)
+		return -1;
+	if (left_cpu > right->cpu)
+		return 1;
+
+#ifdef CONFIG_CGROUP_PERF
+	{
+		const struct cgroup *right_cgroup = event_cgroup(right);
+
+		if (left_cgroup != right_cgroup) {
+			if (!left_cgroup) {
+				/*
+				 * Left has no cgroup but right does, no
+				 * cgroups come first.
+				 */
+				return -1;
+			}
+			if (!right_cgroup) {
+				/*
+				 * Right has no cgroup but left does, no
+				 * cgroups come first.
+				 */
+				return 1;
+			}
+			/* Two dissimilar cgroups, order by id. */
+			if (cgroup_id(left_cgroup) < cgroup_id(right_cgroup))
+				return -1;
+
+			return 1;
+		}
+	}
+#endif
+
+	if (left_group_index < right->group_index)
+		return -1;
+	if (left_group_index > right->group_index)
+		return 1;
+
+	return 0;
+}
+
+#define __node_2_pe(node) \
+	rb_entry((node), struct perf_event, group_node)
+
+static inline bool __group_less(struct rb_node *a, const struct rb_node *b)
+{
+	struct perf_event *e = __node_2_pe(a);
+	return perf_event_groups_cmp(e->cpu, event_cgroup(e), e->group_index,
+				     __node_2_pe(b)) < 0;
+}
+
+struct __group_key {
+	int cpu;
+	struct cgroup *cgroup;
+};
+
+static inline int __group_cmp(const void *key, const struct rb_node *node)
+{
+	const struct __group_key *a = key;
+	const struct perf_event *b = __node_2_pe(node);
+
+	/* partial/subtree match: @cpu, @cgroup; ignore: @group_index */
+	return perf_event_groups_cmp(a->cpu, a->cgroup, b->group_index, b);
+}
+
+/*
+ * Insert @event into @groups' tree; using {@event->cpu, ++@groups->index} for
+ * key (see perf_event_groups_less). This places it last inside the CPU
+ * subtree.
+ */
+static void
+perf_event_groups_insert(struct perf_event_groups *groups,
+			 struct perf_event *event)
+{
+	event->group_index = ++groups->index;
+
+	rb_add(&event->group_node, &groups->tree, __group_less);
+}
+
+/*
+ * Helper function to insert event into the pinned or flexible groups.
+ */
+static void
+add_event_to_groups(struct perf_event *event, struct perf_event_context *ctx)
+{
+	struct perf_event_groups *groups;
+
+	groups = get_event_groups(event, ctx);
+	perf_event_groups_insert(groups, event);
+}
+
+/*
+ * Delete a group from a tree.
+ */
+static void
+perf_event_groups_delete(struct perf_event_groups *groups,
+			 struct perf_event *event)
+{
+	WARN_ON_ONCE(RB_EMPTY_NODE(&event->group_node) ||
+		     RB_EMPTY_ROOT(&groups->tree));
+
+	rb_erase(&event->group_node, &groups->tree);
+	init_event_group(event);
+}
+
+/*
+ * Helper function to delete event from its groups.
+ */
+static void
+del_event_from_groups(struct perf_event *event, struct perf_event_context *ctx)
+{
+	struct perf_event_groups *groups;
+
+	groups = get_event_groups(event, ctx);
+	perf_event_groups_delete(groups, event);
+}
+
+/*
+ * Get the leftmost event in the cpu/cgroup subtree.
+ */
+static struct perf_event *
+perf_event_groups_first(struct perf_event_groups *groups, int cpu,
+			struct cgroup *cgrp)
+{
+	struct __group_key key = {
+		.cpu = cpu,
+		.cgroup = cgrp,
+	};
+	struct rb_node *node;
+
+	node = rb_find_first(&key, &groups->tree, __group_cmp);
+	if (node)
+		return __node_2_pe(node);
+
+	return NULL;
+}
+
+/*
+ * Like rb_entry_next_safe() for the @cpu subtree.
+ */
+static struct perf_event *
+perf_event_groups_next(struct perf_event *event)
+{
+	struct __group_key key = {
+		.cpu = event->cpu,
+		.cgroup = event_cgroup(event),
+	};
+	struct rb_node *next;
+
+	next = rb_next_match(&key, &event->group_node, __group_cmp);
+	if (next)
+		return __node_2_pe(next);
+
+	return NULL;
+}
+
+/*
+ * Iterate through the whole groups tree.
+ */
+#define perf_event_groups_for_each(event, groups)			\
+	for (event = rb_entry_safe(rb_first(&((groups)->tree)),		\
+				typeof(*event), group_node); event;	\
+		event = rb_entry_safe(rb_next(&event->group_node),	\
+				typeof(*event), group_node))
+
+/*
+ * Add an event from the lists for its context.
+ * Must be called with ctx->mutex and ctx->lock held.
+ */
+static void
+list_add_event(struct perf_event *event, struct perf_event_context *ctx)
+{
+	lockdep_assert_held(&ctx->lock);
+
+	WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT);
+	event->attach_state |= PERF_ATTACH_CONTEXT;
+
+	event->tstamp = perf_event_time(event);
+
+	/*
+	 * If we're a stand alone event or group leader, we go to the context
+	 * list, group events are kept attached to the group so that
+	 * perf_group_detach can, at all times, locate all siblings.
+	 */
+	if (event->group_leader == event) {
+		event->group_caps = event->event_caps;
+		add_event_to_groups(event, ctx);
+	}
+
+	list_add_rcu(&event->event_entry, &ctx->event_list);
+	ctx->nr_events++;
+	if (event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT)
+		ctx->nr_user++;
+	if (event->attr.inherit_stat)
+		ctx->nr_stat++;
+
+	if (event->state > PERF_EVENT_STATE_OFF)
+		perf_cgroup_event_enable(event, ctx);
+
+	ctx->generation++;
+}
+
+/*
+ * Initialize event state based on the perf_event_attr::disabled.
+ */
+static inline void perf_event__state_init(struct perf_event *event)
+{
+	event->state = event->attr.disabled ? PERF_EVENT_STATE_OFF :
+					      PERF_EVENT_STATE_INACTIVE;
+}
+
+static int __perf_event_read_size(u64 read_format, int nr_siblings)
+{
+	int entry = sizeof(u64); /* value */
+	int size = 0;
+	int nr = 1;
+
+	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+		size += sizeof(u64);
+
+	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+		size += sizeof(u64);
+
+	if (read_format & PERF_FORMAT_ID)
+		entry += sizeof(u64);
+
+	if (read_format & PERF_FORMAT_LOST)
+		entry += sizeof(u64);
+
+	if (read_format & PERF_FORMAT_GROUP) {
+		nr += nr_siblings;
+		size += sizeof(u64);
+	}
+
+	/*
+	 * Since perf_event_validate_size() limits this to 16k and inhibits
+	 * adding more siblings, this will never overflow.
+	 */
+	return size + nr * entry;
+}
+
+static void __perf_event_header_size(struct perf_event *event, u64 sample_type)
+{
+	struct perf_sample_data *data;
+	u16 size = 0;
+
+	if (sample_type & PERF_SAMPLE_IP)
+		size += sizeof(data->ip);
+
+	if (sample_type & PERF_SAMPLE_ADDR)
+		size += sizeof(data->addr);
+
+	if (sample_type & PERF_SAMPLE_PERIOD)
+		size += sizeof(data->period);
+
+	if (sample_type & PERF_SAMPLE_WEIGHT_TYPE)
+		size += sizeof(data->weight.full);
+
+	if (sample_type & PERF_SAMPLE_READ)
+		size += event->read_size;
+
+	if (sample_type & PERF_SAMPLE_DATA_SRC)
+		size += sizeof(data->data_src.val);
+
+	if (sample_type & PERF_SAMPLE_TRANSACTION)
+		size += sizeof(data->txn);
+
+	if (sample_type & PERF_SAMPLE_PHYS_ADDR)
+		size += sizeof(data->phys_addr);
+
+	if (sample_type & PERF_SAMPLE_CGROUP)
+		size += sizeof(data->cgroup);
+
+	if (sample_type & PERF_SAMPLE_DATA_PAGE_SIZE)
+		size += sizeof(data->data_page_size);
+
+	if (sample_type & PERF_SAMPLE_CODE_PAGE_SIZE)
+		size += sizeof(data->code_page_size);
+
+	event->header_size = size;
+}
+
+/*
+ * Called at perf_event creation and when events are attached/detached from a
+ * group.
+ */
+static void perf_event__header_size(struct perf_event *event)
+{
+	event->read_size =
+		__perf_event_read_size(event->attr.read_format,
+				       event->group_leader->nr_siblings);
+	__perf_event_header_size(event, event->attr.sample_type);
+}
+
+static void perf_event__id_header_size(struct perf_event *event)
+{
+	struct perf_sample_data *data;
+	u64 sample_type = event->attr.sample_type;
+	u16 size = 0;
+
+	if (sample_type & PERF_SAMPLE_TID)
+		size += sizeof(data->tid_entry);
+
+	if (sample_type & PERF_SAMPLE_TIME)
+		size += sizeof(data->time);
+
+	if (sample_type & PERF_SAMPLE_IDENTIFIER)
+		size += sizeof(data->id);
+
+	if (sample_type & PERF_SAMPLE_ID)
+		size += sizeof(data->id);
+
+	if (sample_type & PERF_SAMPLE_STREAM_ID)
+		size += sizeof(data->stream_id);
+
+	if (sample_type & PERF_SAMPLE_CPU)
+		size += sizeof(data->cpu_entry);
+
+	event->id_header_size = size;
+}
+
+/*
+ * Check that adding an event to the group does not result in anybody
+ * overflowing the 64k event limit imposed by the output buffer.
+ *
+ * Specifically, check that the read_size for the event does not exceed 16k,
+ * read_size being the one term that grows with groups size. Since read_size
+ * depends on per-event read_format, also (re)check the existing events.
+ *
+ * This leaves 48k for the constant size fields and things like callchains,
+ * branch stacks and register sets.
+ */
+static bool perf_event_validate_size(struct perf_event *event)
+{
+	struct perf_event *sibling, *group_leader = event->group_leader;
+
+	if (__perf_event_read_size(event->attr.read_format,
+				   group_leader->nr_siblings + 1) > 16*1024)
+		return false;
+
+	if (__perf_event_read_size(group_leader->attr.read_format,
+				   group_leader->nr_siblings + 1) > 16*1024)
+		return false;
+
+	/*
+	 * When creating a new group leader, group_leader->ctx is initialized
+	 * after the size has been validated, but we cannot safely use
+	 * for_each_sibling_event() until group_leader->ctx is set. A new group
+	 * leader cannot have any siblings yet, so we can safely skip checking
+	 * the non-existent siblings.
+	 */
+	if (event == group_leader)
+		return true;
+
+	for_each_sibling_event(sibling, group_leader) {
+		if (__perf_event_read_size(sibling->attr.read_format,
+					   group_leader->nr_siblings + 1) > 16*1024)
+			return false;
+	}
+
+	return true;
+}
+
+static void perf_group_attach(struct perf_event *event)
+{
+	struct perf_event *group_leader = event->group_leader, *pos;
+
+	lockdep_assert_held(&event->ctx->lock);
+
+	/*
+	 * We can have double attach due to group movement in perf_event_open.
+	 */
+	if (event->attach_state & PERF_ATTACH_GROUP)
+		return;
+
+	event->attach_state |= PERF_ATTACH_GROUP;
+
+	if (group_leader == event)
+		return;
+
+	WARN_ON_ONCE(group_leader->ctx != event->ctx);
+
+	group_leader->group_caps &= event->event_caps;
+
+	list_add_tail(&event->sibling_list, &group_leader->sibling_list);
+	group_leader->nr_siblings++;
+	group_leader->group_generation++;
+
+	perf_event__header_size(group_leader);
+
+	for_each_sibling_event(pos, group_leader)
+		perf_event__header_size(pos);
+}
+
+/*
+ * Remove an event from the lists for its context.
+ * Must be called with ctx->mutex and ctx->lock held.
+ */
+static void
+list_del_event(struct perf_event *event, struct perf_event_context *ctx)
+{
+	WARN_ON_ONCE(event->ctx != ctx);
+	lockdep_assert_held(&ctx->lock);
+
+	/*
+	 * We can have double detach due to exit/hot-unplug + close.
+	 */
+	if (!(event->attach_state & PERF_ATTACH_CONTEXT))
+		return;
+
+	event->attach_state &= ~PERF_ATTACH_CONTEXT;
+
+	ctx->nr_events--;
+	if (event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT)
+		ctx->nr_user--;
+	if (event->attr.inherit_stat)
+		ctx->nr_stat--;
+
+	list_del_rcu(&event->event_entry);
+
+	if (event->group_leader == event)
+		del_event_from_groups(event, ctx);
+
+	/*
+	 * If event was in error state, then keep it
+	 * that way, otherwise bogus counts will be
+	 * returned on read(). The only way to get out
+	 * of error state is by explicit re-enabling
+	 * of the event
+	 */
+	if (event->state > PERF_EVENT_STATE_OFF) {
+		perf_cgroup_event_disable(event, ctx);
+		perf_event_set_state(event, PERF_EVENT_STATE_OFF);
+	}
+
+	ctx->generation++;
+}
+
+static int
+perf_aux_output_match(struct perf_event *event, struct perf_event *aux_event)
+{
+	if (!has_aux(aux_event))
+		return 0;
+
+	if (!event->pmu->aux_output_match)
+		return 0;
+
+	return event->pmu->aux_output_match(aux_event);
+}
+
+static void put_event(struct perf_event *event);
+static void event_sched_out(struct perf_event *event,
+			    struct perf_cpu_context *cpuctx,
+			    struct perf_event_context *ctx);
+
+static void perf_put_aux_event(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct perf_event *iter;
+
+	/*
+	 * If event uses aux_event tear down the link
+	 */
+	if (event->aux_event) {
+		iter = event->aux_event;
+		event->aux_event = NULL;
+		put_event(iter);
+		return;
+	}
+
+	/*
+	 * If the event is an aux_event, tear down all links to
+	 * it from other events.
+	 */
+	for_each_sibling_event(iter, event->group_leader) {
+		if (iter->aux_event != event)
+			continue;
+
+		iter->aux_event = NULL;
+		put_event(event);
+
+		/*
+		 * If it's ACTIVE, schedule it out and put it into ERROR
+		 * state so that we don't try to schedule it again. Note
+		 * that perf_event_enable() will clear the ERROR status.
+		 */
+		event_sched_out(iter, cpuctx, ctx);
+		perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
+	}
+}
+
+static bool perf_need_aux_event(struct perf_event *event)
+{
+	return !!event->attr.aux_output || !!event->attr.aux_sample_size;
+}
+
+static int perf_get_aux_event(struct perf_event *event,
+			      struct perf_event *group_leader)
+{
+	/*
+	 * Our group leader must be an aux event if we want to be
+	 * an aux_output. This way, the aux event will precede its
+	 * aux_output events in the group, and therefore will always
+	 * schedule first.
+	 */
+	if (!group_leader)
+		return 0;
+
+	/*
+	 * aux_output and aux_sample_size are mutually exclusive.
+	 */
+	if (event->attr.aux_output && event->attr.aux_sample_size)
+		return 0;
+
+	if (event->attr.aux_output &&
+	    !perf_aux_output_match(event, group_leader))
+		return 0;
+
+	if (event->attr.aux_sample_size && !group_leader->pmu->snapshot_aux)
+		return 0;
+
+	if (!atomic_long_inc_not_zero(&group_leader->refcount))
+		return 0;
+
+	/*
+	 * Link aux_outputs to their aux event; this is undone in
+	 * perf_group_detach() by perf_put_aux_event(). When the
+	 * group in torn down, the aux_output events loose their
+	 * link to the aux_event and can't schedule any more.
+	 */
+	event->aux_event = group_leader;
+
+	return 1;
+}
+
+static inline struct list_head *get_event_list(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+	return event->attr.pinned ? &ctx->pinned_active : &ctx->flexible_active;
+}
+
+/*
+ * Events that have PERF_EV_CAP_SIBLING require being part of a group and
+ * cannot exist on their own, schedule them out and move them into the ERROR
+ * state. Also see _perf_event_enable(), it will not be able to recover
+ * this ERROR state.
+ */
+static inline void perf_remove_sibling_event(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+
+	event_sched_out(event, cpuctx, ctx);
+	perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
+}
+
+static void perf_group_detach(struct perf_event *event)
+{
+	struct perf_event *leader = event->group_leader;
+	struct perf_event *sibling, *tmp;
+	struct perf_event_context *ctx = event->ctx;
+
+	lockdep_assert_held(&ctx->lock);
+
+	/*
+	 * We can have double detach due to exit/hot-unplug + close.
+	 */
+	if (!(event->attach_state & PERF_ATTACH_GROUP))
+		return;
+
+	event->attach_state &= ~PERF_ATTACH_GROUP;
+
+	perf_put_aux_event(event);
+
+	/*
+	 * If this is a sibling, remove it from its group.
+	 */
+	if (leader != event) {
+		list_del_init(&event->sibling_list);
+		event->group_leader->nr_siblings--;
+		event->group_leader->group_generation++;
+		goto out;
+	}
+
+	/*
+	 * If this was a group event with sibling events then
+	 * upgrade the siblings to singleton events by adding them
+	 * to whatever list we are on.
+	 */
+	list_for_each_entry_safe(sibling, tmp, &event->sibling_list, sibling_list) {
+
+		if (sibling->event_caps & PERF_EV_CAP_SIBLING)
+			perf_remove_sibling_event(sibling);
+
+		sibling->group_leader = sibling;
+		list_del_init(&sibling->sibling_list);
+
+		/* Inherit group flags from the previous leader */
+		sibling->group_caps = event->group_caps;
+
+		if (sibling->attach_state & PERF_ATTACH_CONTEXT) {
+			add_event_to_groups(sibling, event->ctx);
+
+			if (sibling->state == PERF_EVENT_STATE_ACTIVE)
+				list_add_tail(&sibling->active_list, get_event_list(sibling));
+		}
+
+		WARN_ON_ONCE(sibling->ctx != event->ctx);
+	}
+
+out:
+	for_each_sibling_event(tmp, leader)
+		perf_event__header_size(tmp);
+
+	perf_event__header_size(leader);
+}
+
+static void sync_child_event(struct perf_event *child_event);
+
+static void perf_child_detach(struct perf_event *event)
+{
+	struct perf_event *parent_event = event->parent;
+
+	if (!(event->attach_state & PERF_ATTACH_CHILD))
+		return;
+
+	event->attach_state &= ~PERF_ATTACH_CHILD;
+
+	if (WARN_ON_ONCE(!parent_event))
+		return;
+
+	lockdep_assert_held(&parent_event->child_mutex);
+
+	sync_child_event(event);
+	list_del_init(&event->child_list);
+}
+
+static bool is_orphaned_event(struct perf_event *event)
+{
+	return event->state == PERF_EVENT_STATE_DEAD;
+}
+
+static inline int __pmu_filter_match(struct perf_event *event)
+{
+	struct pmu *pmu = event->pmu;
+	return pmu->filter_match ? pmu->filter_match(event) : 1;
+}
+
+/*
+ * Check whether we should attempt to schedule an event group based on
+ * PMU-specific filtering. An event group can consist of HW and SW events,
+ * potentially with a SW leader, so we must check all the filters, to
+ * determine whether a group is schedulable:
+ */
+static inline int pmu_filter_match(struct perf_event *event)
+{
+	struct perf_event *sibling;
+	unsigned long flags;
+	int ret = 1;
+
+	if (!__pmu_filter_match(event))
+		return 0;
+
+	local_irq_save(flags);
+	for_each_sibling_event(sibling, event) {
+		if (!__pmu_filter_match(sibling)) {
+			ret = 0;
+			break;
+		}
+	}
+	local_irq_restore(flags);
+
+	return ret;
+}
+
+static inline int
+event_filter_match(struct perf_event *event)
+{
+	return (event->cpu == -1 || event->cpu == smp_processor_id()) &&
+	       perf_cgroup_match(event) && pmu_filter_match(event);
+}
+
+static void
+event_sched_out(struct perf_event *event,
+		  struct perf_cpu_context *cpuctx,
+		  struct perf_event_context *ctx)
+{
+	enum perf_event_state state = PERF_EVENT_STATE_INACTIVE;
+
+	WARN_ON_ONCE(event->ctx != ctx);
+	lockdep_assert_held(&ctx->lock);
+
+	if (event->state != PERF_EVENT_STATE_ACTIVE)
+		return;
+
+	/*
+	 * Asymmetry; we only schedule events _IN_ through ctx_sched_in(), but
+	 * we can schedule events _OUT_ individually through things like
+	 * __perf_remove_from_context().
+	 */
+	list_del_init(&event->active_list);
+
+	perf_pmu_disable(event->pmu);
+
+	event->pmu->del(event, 0);
+	event->oncpu = -1;
+
+	if (event->pending_disable) {
+		event->pending_disable = 0;
+		perf_cgroup_event_disable(event, ctx);
+		state = PERF_EVENT_STATE_OFF;
+	}
+
+	if (event->pending_sigtrap) {
+		bool dec = true;
+
+		event->pending_sigtrap = 0;
+		if (state != PERF_EVENT_STATE_OFF &&
+		    !event->pending_work) {
+			event->pending_work = 1;
+			dec = false;
+			WARN_ON_ONCE(!atomic_long_inc_not_zero(&event->refcount));
+			task_work_add(current, &event->pending_task, TWA_RESUME);
+		}
+		if (dec)
+			local_dec(&event->ctx->nr_pending);
+	}
+
+	perf_event_set_state(event, state);
+
+	if (!is_software_event(event))
+		cpuctx->active_oncpu--;
+	if (!--ctx->nr_active)
+		perf_event_ctx_deactivate(ctx);
+	if (event->attr.freq && event->attr.sample_freq)
+		ctx->nr_freq--;
+	if (event->attr.exclusive || !cpuctx->active_oncpu)
+		cpuctx->exclusive = 0;
+
+	perf_pmu_enable(event->pmu);
+}
+
+static void
+group_sched_out(struct perf_event *group_event,
+		struct perf_cpu_context *cpuctx,
+		struct perf_event_context *ctx)
+{
+	struct perf_event *event;
+
+	if (group_event->state != PERF_EVENT_STATE_ACTIVE)
+		return;
+
+	perf_pmu_disable(ctx->pmu);
+
+	event_sched_out(group_event, cpuctx, ctx);
+
+	/*
+	 * Schedule out siblings (if any):
+	 */
+	for_each_sibling_event(event, group_event)
+		event_sched_out(event, cpuctx, ctx);
+
+	perf_pmu_enable(ctx->pmu);
+}
+
+#define DETACH_GROUP	0x01UL
+#define DETACH_CHILD	0x02UL
+#define DETACH_DEAD	0x04UL
+
+/*
+ * Cross CPU call to remove a performance event
+ *
+ * We disable the event on the hardware level first. After that we
+ * remove it from the context list.
+ */
+static void
+__perf_remove_from_context(struct perf_event *event,
+			   struct perf_cpu_context *cpuctx,
+			   struct perf_event_context *ctx,
+			   void *info)
+{
+	unsigned long flags = (unsigned long)info;
+
+	if (ctx->is_active & EVENT_TIME) {
+		update_context_time(ctx);
+		update_cgrp_time_from_cpuctx(cpuctx, false);
+	}
+
+	/*
+	 * Ensure event_sched_out() switches to OFF, at the very least
+	 * this avoids raising perf_pending_task() at this time.
+	 */
+	if (flags & DETACH_DEAD)
+		event->pending_disable = 1;
+	event_sched_out(event, cpuctx, ctx);
+	if (flags & DETACH_GROUP)
+		perf_group_detach(event);
+	if (flags & DETACH_CHILD)
+		perf_child_detach(event);
+	list_del_event(event, ctx);
+	if (flags & DETACH_DEAD)
+		event->state = PERF_EVENT_STATE_DEAD;
+
+	if (!ctx->nr_events && ctx->is_active) {
+		if (ctx == &cpuctx->ctx)
+			update_cgrp_time_from_cpuctx(cpuctx, true);
+
+		ctx->is_active = 0;
+		ctx->rotate_necessary = 0;
+		if (ctx->task) {
+			WARN_ON_ONCE(cpuctx->task_ctx != ctx);
+			cpuctx->task_ctx = NULL;
+		}
+	}
+}
+
+/*
+ * Remove the event from a task's (or a CPU's) list of events.
+ *
+ * If event->ctx is a cloned context, callers must make sure that
+ * every task struct that event->ctx->task could possibly point to
+ * remains valid.  This is OK when called from perf_release since
+ * that only calls us on the top-level context, which can't be a clone.
+ * When called from perf_event_exit_task, it's OK because the
+ * context has been detached from its task.
+ */
+static void perf_remove_from_context(struct perf_event *event, unsigned long flags)
+{
+	struct perf_event_context *ctx = event->ctx;
+
+	lockdep_assert_held(&ctx->mutex);
+
+	/*
+	 * Because of perf_event_exit_task(), perf_remove_from_context() ought
+	 * to work in the face of TASK_TOMBSTONE, unlike every other
+	 * event_function_call() user.
+	 */
+	raw_spin_lock_irq(&ctx->lock);
+	/*
+	 * Cgroup events are per-cpu events, and must IPI because of
+	 * cgrp_cpuctx_list.
+	 */
+	if (!ctx->is_active && !is_cgroup_event(event)) {
+		__perf_remove_from_context(event, __get_cpu_context(ctx),
+					   ctx, (void *)flags);
+		raw_spin_unlock_irq(&ctx->lock);
+		return;
+	}
+	raw_spin_unlock_irq(&ctx->lock);
+
+	event_function_call(event, __perf_remove_from_context, (void *)flags);
+}
+
+/*
+ * Cross CPU call to disable a performance event
+ */
+static void __perf_event_disable(struct perf_event *event,
+				 struct perf_cpu_context *cpuctx,
+				 struct perf_event_context *ctx,
+				 void *info)
+{
+	if (event->state < PERF_EVENT_STATE_INACTIVE)
+		return;
+
+	if (ctx->is_active & EVENT_TIME) {
+		update_context_time(ctx);
+		update_cgrp_time_from_event(event);
+	}
+
+	if (event == event->group_leader)
+		group_sched_out(event, cpuctx, ctx);
+	else
+		event_sched_out(event, cpuctx, ctx);
+
+	perf_event_set_state(event, PERF_EVENT_STATE_OFF);
+	perf_cgroup_event_disable(event, ctx);
+}
+
+/*
+ * Disable an event.
+ *
+ * If event->ctx is a cloned context, callers must make sure that
+ * every task struct that event->ctx->task could possibly point to
+ * remains valid.  This condition is satisfied when called through
+ * perf_event_for_each_child or perf_event_for_each because they
+ * hold the top-level event's child_mutex, so any descendant that
+ * goes to exit will block in perf_event_exit_event().
+ *
+ * When called from perf_pending_irq it's OK because event->ctx
+ * is the current context on this CPU and preemption is disabled,
+ * hence we can't get into perf_event_task_sched_out for this context.
+ */
+static void _perf_event_disable(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+
+	raw_spin_lock_irq(&ctx->lock);
+	if (event->state <= PERF_EVENT_STATE_OFF) {
+		raw_spin_unlock_irq(&ctx->lock);
+		return;
+	}
+	raw_spin_unlock_irq(&ctx->lock);
+
+	event_function_call(event, __perf_event_disable, NULL);
+}
+
+void perf_event_disable_local(struct perf_event *event)
+{
+	event_function_local(event, __perf_event_disable, NULL);
+}
+
+/*
+ * Strictly speaking kernel users cannot create groups and therefore this
+ * interface does not need the perf_event_ctx_lock() magic.
+ */
+void perf_event_disable(struct perf_event *event)
+{
+	struct perf_event_context *ctx;
+
+	ctx = perf_event_ctx_lock(event);
+	_perf_event_disable(event);
+	perf_event_ctx_unlock(event, ctx);
+}
+EXPORT_SYMBOL_GPL(perf_event_disable);
+
+void perf_event_disable_inatomic(struct perf_event *event)
+{
+	event->pending_disable = 1;
+	irq_work_queue(&event->pending_irq);
+}
+
+#define MAX_INTERRUPTS (~0ULL)
+
+static void perf_log_throttle(struct perf_event *event, int enable);
+static void perf_log_itrace_start(struct perf_event *event);
+
+static int
+event_sched_in(struct perf_event *event,
+		 struct perf_cpu_context *cpuctx,
+		 struct perf_event_context *ctx)
+{
+	int ret = 0;
+
+	WARN_ON_ONCE(event->ctx != ctx);
+
+	lockdep_assert_held(&ctx->lock);
+
+	if (event->state <= PERF_EVENT_STATE_OFF)
+		return 0;
+
+	WRITE_ONCE(event->oncpu, smp_processor_id());
+	/*
+	 * Order event::oncpu write to happen before the ACTIVE state is
+	 * visible. This allows perf_event_{stop,read}() to observe the correct
+	 * ->oncpu if it sees ACTIVE.
+	 */
+	smp_wmb();
+	perf_event_set_state(event, PERF_EVENT_STATE_ACTIVE);
+
+	/*
+	 * Unthrottle events, since we scheduled we might have missed several
+	 * ticks already, also for a heavily scheduling task there is little
+	 * guarantee it'll get a tick in a timely manner.
+	 */
+	if (unlikely(event->hw.interrupts == MAX_INTERRUPTS)) {
+		perf_log_throttle(event, 1);
+		event->hw.interrupts = 0;
+	}
+
+	perf_pmu_disable(event->pmu);
+
+	perf_log_itrace_start(event);
+
+	if (event->pmu->add(event, PERF_EF_START)) {
+		perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE);
+		event->oncpu = -1;
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	if (!is_software_event(event))
+		cpuctx->active_oncpu++;
+	if (!ctx->nr_active++)
+		perf_event_ctx_activate(ctx);
+	if (event->attr.freq && event->attr.sample_freq)
+		ctx->nr_freq++;
+
+	if (event->attr.exclusive)
+		cpuctx->exclusive = 1;
+
+out:
+	perf_pmu_enable(event->pmu);
+
+	return ret;
+}
+
+static int
+group_sched_in(struct perf_event *group_event,
+	       struct perf_cpu_context *cpuctx,
+	       struct perf_event_context *ctx)
+{
+	struct perf_event *event, *partial_group = NULL;
+	struct pmu *pmu = ctx->pmu;
+
+	if (group_event->state == PERF_EVENT_STATE_OFF)
+		return 0;
+
+	pmu->start_txn(pmu, PERF_PMU_TXN_ADD);
+
+	if (event_sched_in(group_event, cpuctx, ctx))
+		goto error;
+
+	/*
+	 * Schedule in siblings as one group (if any):
+	 */
+	for_each_sibling_event(event, group_event) {
+		if (event_sched_in(event, cpuctx, ctx)) {
+			partial_group = event;
+			goto group_error;
+		}
+	}
+
+	if (!pmu->commit_txn(pmu))
+		return 0;
+
+group_error:
+	/*
+	 * Groups can be scheduled in as one unit only, so undo any
+	 * partial group before returning:
+	 * The events up to the failed event are scheduled out normally.
+	 */
+	for_each_sibling_event(event, group_event) {
+		if (event == partial_group)
+			break;
+
+		event_sched_out(event, cpuctx, ctx);
+	}
+	event_sched_out(group_event, cpuctx, ctx);
+
+error:
+	pmu->cancel_txn(pmu);
+	return -EAGAIN;
+}
+
+/*
+ * Work out whether we can put this event group on the CPU now.
+ */
+static int group_can_go_on(struct perf_event *event,
+			   struct perf_cpu_context *cpuctx,
+			   int can_add_hw)
+{
+	/*
+	 * Groups consisting entirely of software events can always go on.
+	 */
+	if (event->group_caps & PERF_EV_CAP_SOFTWARE)
+		return 1;
+	/*
+	 * If an exclusive group is already on, no other hardware
+	 * events can go on.
+	 */
+	if (cpuctx->exclusive)
+		return 0;
+	/*
+	 * If this group is exclusive and there are already
+	 * events on the CPU, it can't go on.
+	 */
+	if (event->attr.exclusive && !list_empty(get_event_list(event)))
+		return 0;
+	/*
+	 * Otherwise, try to add it if all previous groups were able
+	 * to go on.
+	 */
+	return can_add_hw;
+}
+
+static void add_event_to_ctx(struct perf_event *event,
+			       struct perf_event_context *ctx)
+{
+	list_add_event(event, ctx);
+	perf_group_attach(event);
+}
+
+static void ctx_sched_out(struct perf_event_context *ctx,
+			  struct perf_cpu_context *cpuctx,
+			  enum event_type_t event_type);
+static void
+ctx_sched_in(struct perf_event_context *ctx,
+	     struct perf_cpu_context *cpuctx,
+	     enum event_type_t event_type);
+
+static void task_ctx_sched_out(struct perf_cpu_context *cpuctx,
+			       struct perf_event_context *ctx,
+			       enum event_type_t event_type)
+{
+	if (!cpuctx->task_ctx)
+		return;
+
+	if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
+		return;
+
+	ctx_sched_out(ctx, cpuctx, event_type);
+}
+
+static void perf_event_sched_in(struct perf_cpu_context *cpuctx,
+				struct perf_event_context *ctx)
+{
+	cpu_ctx_sched_in(cpuctx, EVENT_PINNED);
+	if (ctx)
+		ctx_sched_in(ctx, cpuctx, EVENT_PINNED);
+	cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
+	if (ctx)
+		ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE);
+}
+
+/*
+ * We want to maintain the following priority of scheduling:
+ *  - CPU pinned (EVENT_CPU | EVENT_PINNED)
+ *  - task pinned (EVENT_PINNED)
+ *  - CPU flexible (EVENT_CPU | EVENT_FLEXIBLE)
+ *  - task flexible (EVENT_FLEXIBLE).
+ *
+ * In order to avoid unscheduling and scheduling back in everything every
+ * time an event is added, only do it for the groups of equal priority and
+ * below.
+ *
+ * This can be called after a batch operation on task events, in which case
+ * event_type is a bit mask of the types of events involved. For CPU events,
+ * event_type is only either EVENT_PINNED or EVENT_FLEXIBLE.
+ */
+static void ctx_resched(struct perf_cpu_context *cpuctx,
+			struct perf_event_context *task_ctx,
+			enum event_type_t event_type)
+{
+	enum event_type_t ctx_event_type;
+	bool cpu_event = !!(event_type & EVENT_CPU);
+
+	/*
+	 * If pinned groups are involved, flexible groups also need to be
+	 * scheduled out.
+	 */
+	if (event_type & EVENT_PINNED)
+		event_type |= EVENT_FLEXIBLE;
+
+	ctx_event_type = event_type & EVENT_ALL;
+
+	perf_pmu_disable(cpuctx->ctx.pmu);
+	if (task_ctx)
+		task_ctx_sched_out(cpuctx, task_ctx, event_type);
+
+	/*
+	 * Decide which cpu ctx groups to schedule out based on the types
+	 * of events that caused rescheduling:
+	 *  - EVENT_CPU: schedule out corresponding groups;
+	 *  - EVENT_PINNED task events: schedule out EVENT_FLEXIBLE groups;
+	 *  - otherwise, do nothing more.
+	 */
+	if (cpu_event)
+		cpu_ctx_sched_out(cpuctx, ctx_event_type);
+	else if (ctx_event_type & EVENT_PINNED)
+		cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+
+	perf_event_sched_in(cpuctx, task_ctx);
+	perf_pmu_enable(cpuctx->ctx.pmu);
+}
+
+void perf_pmu_resched(struct pmu *pmu)
+{
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+	struct perf_event_context *task_ctx = cpuctx->task_ctx;
+
+	perf_ctx_lock(cpuctx, task_ctx);
+	ctx_resched(cpuctx, task_ctx, EVENT_ALL|EVENT_CPU);
+	perf_ctx_unlock(cpuctx, task_ctx);
+}
+
+/*
+ * Cross CPU call to install and enable a performance event
+ *
+ * Very similar to remote_function() + event_function() but cannot assume that
+ * things like ctx->is_active and cpuctx->task_ctx are set.
+ */
+static int  __perf_install_in_context(void *info)
+{
+	struct perf_event *event = info;
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct perf_event_context *task_ctx = cpuctx->task_ctx;
+	bool reprogram = true;
+	int ret = 0;
+
+	raw_spin_lock(&cpuctx->ctx.lock);
+	if (ctx->task) {
+		raw_spin_lock(&ctx->lock);
+		task_ctx = ctx;
+
+		reprogram = (ctx->task == current);
+
+		/*
+		 * If the task is running, it must be running on this CPU,
+		 * otherwise we cannot reprogram things.
+		 *
+		 * If its not running, we don't care, ctx->lock will
+		 * serialize against it becoming runnable.
+		 */
+		if (task_curr(ctx->task) && !reprogram) {
+			ret = -ESRCH;
+			goto unlock;
+		}
+
+		WARN_ON_ONCE(reprogram && cpuctx->task_ctx && cpuctx->task_ctx != ctx);
+	} else if (task_ctx) {
+		raw_spin_lock(&task_ctx->lock);
+	}
+
+#ifdef CONFIG_CGROUP_PERF
+	if (event->state > PERF_EVENT_STATE_OFF && is_cgroup_event(event)) {
+		/*
+		 * If the current cgroup doesn't match the event's
+		 * cgroup, we should not try to schedule it.
+		 */
+		struct perf_cgroup *cgrp = perf_cgroup_from_task(current, ctx);
+		reprogram = cgroup_is_descendant(cgrp->css.cgroup,
+					event->cgrp->css.cgroup);
+	}
+#endif
+
+	if (reprogram) {
+		ctx_sched_out(ctx, cpuctx, EVENT_TIME);
+		add_event_to_ctx(event, ctx);
+		ctx_resched(cpuctx, task_ctx, get_event_type(event));
+	} else {
+		add_event_to_ctx(event, ctx);
+	}
+
+unlock:
+	perf_ctx_unlock(cpuctx, task_ctx);
+
+	return ret;
+}
+
+static bool exclusive_event_installable(struct perf_event *event,
+					struct perf_event_context *ctx);
+
+/*
+ * Attach a performance event to a context.
+ *
+ * Very similar to event_function_call, see comment there.
+ */
+static void
+perf_install_in_context(struct perf_event_context *ctx,
+			struct perf_event *event,
+			int cpu)
+{
+	struct task_struct *task = READ_ONCE(ctx->task);
+
+	lockdep_assert_held(&ctx->mutex);
+
+	WARN_ON_ONCE(!exclusive_event_installable(event, ctx));
+
+	if (event->cpu != -1)
+		event->cpu = cpu;
+
+	/*
+	 * Ensures that if we can observe event->ctx, both the event and ctx
+	 * will be 'complete'. See perf_iterate_sb_cpu().
+	 */
+	smp_store_release(&event->ctx, ctx);
+
+	/*
+	 * perf_event_attr::disabled events will not run and can be initialized
+	 * without IPI. Except when this is the first event for the context, in
+	 * that case we need the magic of the IPI to set ctx->is_active.
+	 * Similarly, cgroup events for the context also needs the IPI to
+	 * manipulate the cgrp_cpuctx_list.
+	 *
+	 * The IOC_ENABLE that is sure to follow the creation of a disabled
+	 * event will issue the IPI and reprogram the hardware.
+	 */
+	if (__perf_effective_state(event) == PERF_EVENT_STATE_OFF &&
+	    ctx->nr_events && !is_cgroup_event(event)) {
+		raw_spin_lock_irq(&ctx->lock);
+		if (ctx->task == TASK_TOMBSTONE) {
+			raw_spin_unlock_irq(&ctx->lock);
+			return;
+		}
+		add_event_to_ctx(event, ctx);
+		raw_spin_unlock_irq(&ctx->lock);
+		return;
+	}
+
+	if (!task) {
+		cpu_function_call(cpu, __perf_install_in_context, event);
+		return;
+	}
+
+	/*
+	 * Should not happen, we validate the ctx is still alive before calling.
+	 */
+	if (WARN_ON_ONCE(task == TASK_TOMBSTONE))
+		return;
+
+	/*
+	 * Installing events is tricky because we cannot rely on ctx->is_active
+	 * to be set in case this is the nr_events 0 -> 1 transition.
+	 *
+	 * Instead we use task_curr(), which tells us if the task is running.
+	 * However, since we use task_curr() outside of rq::lock, we can race
+	 * against the actual state. This means the result can be wrong.
+	 *
+	 * If we get a false positive, we retry, this is harmless.
+	 *
+	 * If we get a false negative, things are complicated. If we are after
+	 * perf_event_context_sched_in() ctx::lock will serialize us, and the
+	 * value must be correct. If we're before, it doesn't matter since
+	 * perf_event_context_sched_in() will program the counter.
+	 *
+	 * However, this hinges on the remote context switch having observed
+	 * our task->perf_event_ctxp[] store, such that it will in fact take
+	 * ctx::lock in perf_event_context_sched_in().
+	 *
+	 * We do this by task_function_call(), if the IPI fails to hit the task
+	 * we know any future context switch of task must see the
+	 * perf_event_ctpx[] store.
+	 */
+
+	/*
+	 * This smp_mb() orders the task->perf_event_ctxp[] store with the
+	 * task_cpu() load, such that if the IPI then does not find the task
+	 * running, a future context switch of that task must observe the
+	 * store.
+	 */
+	smp_mb();
+again:
+	if (!task_function_call(task, __perf_install_in_context, event))
+		return;
+
+	raw_spin_lock_irq(&ctx->lock);
+	task = ctx->task;
+	if (WARN_ON_ONCE(task == TASK_TOMBSTONE)) {
+		/*
+		 * Cannot happen because we already checked above (which also
+		 * cannot happen), and we hold ctx->mutex, which serializes us
+		 * against perf_event_exit_task_context().
+		 */
+		raw_spin_unlock_irq(&ctx->lock);
+		return;
+	}
+	/*
+	 * If the task is not running, ctx->lock will avoid it becoming so,
+	 * thus we can safely install the event.
+	 */
+	if (task_curr(task)) {
+		raw_spin_unlock_irq(&ctx->lock);
+		goto again;
+	}
+	add_event_to_ctx(event, ctx);
+	raw_spin_unlock_irq(&ctx->lock);
+}
+
+/*
+ * Cross CPU call to enable a performance event
+ */
+static void __perf_event_enable(struct perf_event *event,
+				struct perf_cpu_context *cpuctx,
+				struct perf_event_context *ctx,
+				void *info)
+{
+	struct perf_event *leader = event->group_leader;
+	struct perf_event_context *task_ctx;
+
+	if (event->state >= PERF_EVENT_STATE_INACTIVE ||
+	    event->state <= PERF_EVENT_STATE_ERROR)
+		return;
+
+	if (ctx->is_active)
+		ctx_sched_out(ctx, cpuctx, EVENT_TIME);
+
+	perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE);
+	perf_cgroup_event_enable(event, ctx);
+
+	if (!ctx->is_active)
+		return;
+
+	if (!event_filter_match(event)) {
+		ctx_sched_in(ctx, cpuctx, EVENT_TIME);
+		return;
+	}
+
+	/*
+	 * If the event is in a group and isn't the group leader,
+	 * then don't put it on unless the group is on.
+	 */
+	if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE) {
+		ctx_sched_in(ctx, cpuctx, EVENT_TIME);
+		return;
+	}
+
+	task_ctx = cpuctx->task_ctx;
+	if (ctx->task)
+		WARN_ON_ONCE(task_ctx != ctx);
+
+	ctx_resched(cpuctx, task_ctx, get_event_type(event));
+}
+
+/*
+ * Enable an event.
+ *
+ * If event->ctx is a cloned context, callers must make sure that
+ * every task struct that event->ctx->task could possibly point to
+ * remains valid.  This condition is satisfied when called through
+ * perf_event_for_each_child or perf_event_for_each as described
+ * for perf_event_disable.
+ */
+static void _perf_event_enable(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+
+	raw_spin_lock_irq(&ctx->lock);
+	if (event->state >= PERF_EVENT_STATE_INACTIVE ||
+	    event->state <  PERF_EVENT_STATE_ERROR) {
+out:
+		raw_spin_unlock_irq(&ctx->lock);
+		return;
+	}
+
+	/*
+	 * If the event is in error state, clear that first.
+	 *
+	 * That way, if we see the event in error state below, we know that it
+	 * has gone back into error state, as distinct from the task having
+	 * been scheduled away before the cross-call arrived.
+	 */
+	if (event->state == PERF_EVENT_STATE_ERROR) {
+		/*
+		 * Detached SIBLING events cannot leave ERROR state.
+		 */
+		if (event->event_caps & PERF_EV_CAP_SIBLING &&
+		    event->group_leader == event)
+			goto out;
+
+		event->state = PERF_EVENT_STATE_OFF;
+	}
+	raw_spin_unlock_irq(&ctx->lock);
+
+	event_function_call(event, __perf_event_enable, NULL);
+}
+
+/*
+ * See perf_event_disable();
+ */
+void perf_event_enable(struct perf_event *event)
+{
+	struct perf_event_context *ctx;
+
+	ctx = perf_event_ctx_lock(event);
+	_perf_event_enable(event);
+	perf_event_ctx_unlock(event, ctx);
+}
+EXPORT_SYMBOL_GPL(perf_event_enable);
+
+struct stop_event_data {
+	struct perf_event	*event;
+	unsigned int		restart;
+};
+
+static int __perf_event_stop(void *info)
+{
+	struct stop_event_data *sd = info;
+	struct perf_event *event = sd->event;
+
+	/* if it's already INACTIVE, do nothing */
+	if (READ_ONCE(event->state) != PERF_EVENT_STATE_ACTIVE)
+		return 0;
+
+	/* matches smp_wmb() in event_sched_in() */
+	smp_rmb();
+
+	/*
+	 * There is a window with interrupts enabled before we get here,
+	 * so we need to check again lest we try to stop another CPU's event.
+	 */
+	if (READ_ONCE(event->oncpu) != smp_processor_id())
+		return -EAGAIN;
+
+	event->pmu->stop(event, PERF_EF_UPDATE);
+
+	/*
+	 * May race with the actual stop (through perf_pmu_output_stop()),
+	 * but it is only used for events with AUX ring buffer, and such
+	 * events will refuse to restart because of rb::aux_mmap_count==0,
+	 * see comments in perf_aux_output_begin().
+	 *
+	 * Since this is happening on an event-local CPU, no trace is lost
+	 * while restarting.
+	 */
+	if (sd->restart)
+		event->pmu->start(event, 0);
+
+	return 0;
+}
+
+static int perf_event_stop(struct perf_event *event, int restart)
+{
+	struct stop_event_data sd = {
+		.event		= event,
+		.restart	= restart,
+	};
+	int ret = 0;
+
+	do {
+		if (READ_ONCE(event->state) != PERF_EVENT_STATE_ACTIVE)
+			return 0;
+
+		/* matches smp_wmb() in event_sched_in() */
+		smp_rmb();
+
+		/*
+		 * We only want to restart ACTIVE events, so if the event goes
+		 * inactive here (event->oncpu==-1), there's nothing more to do;
+		 * fall through with ret==-ENXIO.
+		 */
+		ret = cpu_function_call(READ_ONCE(event->oncpu),
+					__perf_event_stop, &sd);
+	} while (ret == -EAGAIN);
+
+	return ret;
+}
+
+/*
+ * In order to contain the amount of racy and tricky in the address filter
+ * configuration management, it is a two part process:
+ *
+ * (p1) when userspace mappings change as a result of (1) or (2) or (3) below,
+ *      we update the addresses of corresponding vmas in
+ *	event::addr_filter_ranges array and bump the event::addr_filters_gen;
+ * (p2) when an event is scheduled in (pmu::add), it calls
+ *      perf_event_addr_filters_sync() which calls pmu::addr_filters_sync()
+ *      if the generation has changed since the previous call.
+ *
+ * If (p1) happens while the event is active, we restart it to force (p2).
+ *
+ * (1) perf_addr_filters_apply(): adjusting filters' offsets based on
+ *     pre-existing mappings, called once when new filters arrive via SET_FILTER
+ *     ioctl;
+ * (2) perf_addr_filters_adjust(): adjusting filters' offsets based on newly
+ *     registered mapping, called for every new mmap(), with mm::mmap_lock down
+ *     for reading;
+ * (3) perf_event_addr_filters_exec(): clearing filters' offsets in the process
+ *     of exec.
+ */
+void perf_event_addr_filters_sync(struct perf_event *event)
+{
+	struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
+
+	if (!has_addr_filter(event))
+		return;
+
+	raw_spin_lock(&ifh->lock);
+	if (event->addr_filters_gen != event->hw.addr_filters_gen) {
+		event->pmu->addr_filters_sync(event);
+		event->hw.addr_filters_gen = event->addr_filters_gen;
+	}
+	raw_spin_unlock(&ifh->lock);
+}
+EXPORT_SYMBOL_GPL(perf_event_addr_filters_sync);
+
+static int _perf_event_refresh(struct perf_event *event, int refresh)
+{
+	/*
+	 * not supported on inherited events
+	 */
+	if (event->attr.inherit || !is_sampling_event(event))
+		return -EINVAL;
+
+	atomic_add(refresh, &event->event_limit);
+	_perf_event_enable(event);
+
+	return 0;
+}
+
+/*
+ * See perf_event_disable()
+ */
+int perf_event_refresh(struct perf_event *event, int refresh)
+{
+	struct perf_event_context *ctx;
+	int ret;
+
+	ctx = perf_event_ctx_lock(event);
+	ret = _perf_event_refresh(event, refresh);
+	perf_event_ctx_unlock(event, ctx);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(perf_event_refresh);
+
+static int perf_event_modify_breakpoint(struct perf_event *bp,
+					 struct perf_event_attr *attr)
+{
+	int err;
+
+	_perf_event_disable(bp);
+
+	err = modify_user_hw_breakpoint_check(bp, attr, true);
+
+	if (!bp->attr.disabled)
+		_perf_event_enable(bp);
+
+	return err;
+}
+
+/*
+ * Copy event-type-independent attributes that may be modified.
+ */
+static void perf_event_modify_copy_attr(struct perf_event_attr *to,
+					const struct perf_event_attr *from)
+{
+	to->sig_data = from->sig_data;
+}
+
+static int perf_event_modify_attr(struct perf_event *event,
+				  struct perf_event_attr *attr)
+{
+	int (*func)(struct perf_event *, struct perf_event_attr *);
+	struct perf_event *child;
+	int err;
+
+	if (event->attr.type != attr->type)
+		return -EINVAL;
+
+	switch (event->attr.type) {
+	case PERF_TYPE_BREAKPOINT:
+		func = perf_event_modify_breakpoint;
+		break;
+	default:
+		/* Place holder for future additions. */
+		return -EOPNOTSUPP;
+	}
+
+	WARN_ON_ONCE(event->ctx->parent_ctx);
+
+	mutex_lock(&event->child_mutex);
+	/*
+	 * Event-type-independent attributes must be copied before event-type
+	 * modification, which will validate that final attributes match the
+	 * source attributes after all relevant attributes have been copied.
+	 */
+	perf_event_modify_copy_attr(&event->attr, attr);
+	err = func(event, attr);
+	if (err)
+		goto out;
+	list_for_each_entry(child, &event->child_list, child_list) {
+		perf_event_modify_copy_attr(&child->attr, attr);
+		err = func(child, attr);
+		if (err)
+			goto out;
+	}
+out:
+	mutex_unlock(&event->child_mutex);
+	return err;
+}
+
+static void ctx_sched_out(struct perf_event_context *ctx,
+			  struct perf_cpu_context *cpuctx,
+			  enum event_type_t event_type)
+{
+	struct perf_event *event, *tmp;
+	int is_active = ctx->is_active;
+
+	lockdep_assert_held(&ctx->lock);
+
+	if (likely(!ctx->nr_events)) {
+		/*
+		 * See __perf_remove_from_context().
+		 */
+		WARN_ON_ONCE(ctx->is_active);
+		if (ctx->task)
+			WARN_ON_ONCE(cpuctx->task_ctx);
+		return;
+	}
+
+	/*
+	 * Always update time if it was set; not only when it changes.
+	 * Otherwise we can 'forget' to update time for any but the last
+	 * context we sched out. For example:
+	 *
+	 *   ctx_sched_out(.event_type = EVENT_FLEXIBLE)
+	 *   ctx_sched_out(.event_type = EVENT_PINNED)
+	 *
+	 * would only update time for the pinned events.
+	 */
+	if (is_active & EVENT_TIME) {
+		/* update (and stop) ctx time */
+		update_context_time(ctx);
+		update_cgrp_time_from_cpuctx(cpuctx, ctx == &cpuctx->ctx);
+		/*
+		 * CPU-release for the below ->is_active store,
+		 * see __load_acquire() in perf_event_time_now()
+		 */
+		barrier();
+	}
+
+	ctx->is_active &= ~event_type;
+	if (!(ctx->is_active & EVENT_ALL))
+		ctx->is_active = 0;
+
+	if (ctx->task) {
+		WARN_ON_ONCE(cpuctx->task_ctx != ctx);
+		if (!ctx->is_active)
+			cpuctx->task_ctx = NULL;
+	}
+
+	is_active ^= ctx->is_active; /* changed bits */
+
+	if (!ctx->nr_active || !(is_active & EVENT_ALL))
+		return;
+
+	perf_pmu_disable(ctx->pmu);
+	if (is_active & EVENT_PINNED) {
+		list_for_each_entry_safe(event, tmp, &ctx->pinned_active, active_list)
+			group_sched_out(event, cpuctx, ctx);
+	}
+
+	if (is_active & EVENT_FLEXIBLE) {
+		list_for_each_entry_safe(event, tmp, &ctx->flexible_active, active_list)
+			group_sched_out(event, cpuctx, ctx);
+
+		/*
+		 * Since we cleared EVENT_FLEXIBLE, also clear
+		 * rotate_necessary, is will be reset by
+		 * ctx_flexible_sched_in() when needed.
+		 */
+		ctx->rotate_necessary = 0;
+	}
+	perf_pmu_enable(ctx->pmu);
+}
+
+/*
+ * Test whether two contexts are equivalent, i.e. whether they have both been
+ * cloned from the same version of the same context.
+ *
+ * Equivalence is measured using a generation number in the context that is
+ * incremented on each modification to it; see unclone_ctx(), list_add_event()
+ * and list_del_event().
+ */
+static int context_equiv(struct perf_event_context *ctx1,
+			 struct perf_event_context *ctx2)
+{
+	lockdep_assert_held(&ctx1->lock);
+	lockdep_assert_held(&ctx2->lock);
+
+	/* Pinning disables the swap optimization */
+	if (ctx1->pin_count || ctx2->pin_count)
+		return 0;
+
+	/* If ctx1 is the parent of ctx2 */
+	if (ctx1 == ctx2->parent_ctx && ctx1->generation == ctx2->parent_gen)
+		return 1;
+
+	/* If ctx2 is the parent of ctx1 */
+	if (ctx1->parent_ctx == ctx2 && ctx1->parent_gen == ctx2->generation)
+		return 1;
+
+	/*
+	 * If ctx1 and ctx2 have the same parent; we flatten the parent
+	 * hierarchy, see perf_event_init_context().
+	 */
+	if (ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx &&
+			ctx1->parent_gen == ctx2->parent_gen)
+		return 1;
+
+	/* Unmatched */
+	return 0;
+}
+
+static void __perf_event_sync_stat(struct perf_event *event,
+				     struct perf_event *next_event)
+{
+	u64 value;
+
+	if (!event->attr.inherit_stat)
+		return;
+
+	/*
+	 * Update the event value, we cannot use perf_event_read()
+	 * because we're in the middle of a context switch and have IRQs
+	 * disabled, which upsets smp_call_function_single(), however
+	 * we know the event must be on the current CPU, therefore we
+	 * don't need to use it.
+	 */
+	if (event->state == PERF_EVENT_STATE_ACTIVE)
+		event->pmu->read(event);
+
+	perf_event_update_time(event);
+
+	/*
+	 * In order to keep per-task stats reliable we need to flip the event
+	 * values when we flip the contexts.
+	 */
+	value = local64_read(&next_event->count);
+	value = local64_xchg(&event->count, value);
+	local64_set(&next_event->count, value);
+
+	swap(event->total_time_enabled, next_event->total_time_enabled);
+	swap(event->total_time_running, next_event->total_time_running);
+
+	/*
+	 * Since we swizzled the values, update the user visible data too.
+	 */
+	perf_event_update_userpage(event);
+	perf_event_update_userpage(next_event);
+}
+
+static void perf_event_sync_stat(struct perf_event_context *ctx,
+				   struct perf_event_context *next_ctx)
+{
+	struct perf_event *event, *next_event;
+
+	if (!ctx->nr_stat)
+		return;
+
+	update_context_time(ctx);
+
+	event = list_first_entry(&ctx->event_list,
+				   struct perf_event, event_entry);
+
+	next_event = list_first_entry(&next_ctx->event_list,
+					struct perf_event, event_entry);
+
+	while (&event->event_entry != &ctx->event_list &&
+	       &next_event->event_entry != &next_ctx->event_list) {
+
+		__perf_event_sync_stat(event, next_event);
+
+		event = list_next_entry(event, event_entry);
+		next_event = list_next_entry(next_event, event_entry);
+	}
+}
+
+static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
+					 struct task_struct *next)
+{
+	struct perf_event_context *ctx = task->perf_event_ctxp[ctxn];
+	struct perf_event_context *next_ctx;
+	struct perf_event_context *parent, *next_parent;
+	struct perf_cpu_context *cpuctx;
+	int do_switch = 1;
+	struct pmu *pmu;
+
+	if (likely(!ctx))
+		return;
+
+	pmu = ctx->pmu;
+	cpuctx = __get_cpu_context(ctx);
+	if (!cpuctx->task_ctx)
+		return;
+
+	rcu_read_lock();
+	next_ctx = next->perf_event_ctxp[ctxn];
+	if (!next_ctx)
+		goto unlock;
+
+	parent = rcu_dereference(ctx->parent_ctx);
+	next_parent = rcu_dereference(next_ctx->parent_ctx);
+
+	/* If neither context have a parent context; they cannot be clones. */
+	if (!parent && !next_parent)
+		goto unlock;
+
+	if (next_parent == ctx || next_ctx == parent || next_parent == parent) {
+		/*
+		 * Looks like the two contexts are clones, so we might be
+		 * able to optimize the context switch.  We lock both
+		 * contexts and check that they are clones under the
+		 * lock (including re-checking that neither has been
+		 * uncloned in the meantime).  It doesn't matter which
+		 * order we take the locks because no other cpu could
+		 * be trying to lock both of these tasks.
+		 */
+		raw_spin_lock(&ctx->lock);
+		raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
+		if (context_equiv(ctx, next_ctx)) {
+
+			perf_pmu_disable(pmu);
+
+			/* PMIs are disabled; ctx->nr_pending is stable. */
+			if (local_read(&ctx->nr_pending) ||
+			    local_read(&next_ctx->nr_pending)) {
+				/*
+				 * Must not swap out ctx when there's pending
+				 * events that rely on the ctx->task relation.
+				 */
+				raw_spin_unlock(&next_ctx->lock);
+				rcu_read_unlock();
+				goto inside_switch;
+			}
+
+			WRITE_ONCE(ctx->task, next);
+			WRITE_ONCE(next_ctx->task, task);
+
+			if (cpuctx->sched_cb_usage && pmu->sched_task)
+				pmu->sched_task(ctx, false);
+
+			/*
+			 * PMU specific parts of task perf context can require
+			 * additional synchronization. As an example of such
+			 * synchronization see implementation details of Intel
+			 * LBR call stack data profiling;
+			 */
+			if (pmu->swap_task_ctx)
+				pmu->swap_task_ctx(ctx, next_ctx);
+			else
+				swap(ctx->task_ctx_data, next_ctx->task_ctx_data);
+
+			perf_pmu_enable(pmu);
+
+			/*
+			 * RCU_INIT_POINTER here is safe because we've not
+			 * modified the ctx and the above modification of
+			 * ctx->task and ctx->task_ctx_data are immaterial
+			 * since those values are always verified under
+			 * ctx->lock which we're now holding.
+			 */
+			RCU_INIT_POINTER(task->perf_event_ctxp[ctxn], next_ctx);
+			RCU_INIT_POINTER(next->perf_event_ctxp[ctxn], ctx);
+
+			do_switch = 0;
+
+			perf_event_sync_stat(ctx, next_ctx);
+		}
+		raw_spin_unlock(&next_ctx->lock);
+		raw_spin_unlock(&ctx->lock);
+	}
+unlock:
+	rcu_read_unlock();
+
+	if (do_switch) {
+		raw_spin_lock(&ctx->lock);
+		perf_pmu_disable(pmu);
+
+inside_switch:
+		if (cpuctx->sched_cb_usage && pmu->sched_task)
+			pmu->sched_task(ctx, false);
+		task_ctx_sched_out(cpuctx, ctx, EVENT_ALL);
+
+		perf_pmu_enable(pmu);
+		raw_spin_unlock(&ctx->lock);
+	}
+}
+
+static DEFINE_PER_CPU(struct list_head, sched_cb_list);
+
+void perf_sched_cb_dec(struct pmu *pmu)
+{
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+
+	this_cpu_dec(perf_sched_cb_usages);
+
+	if (!--cpuctx->sched_cb_usage)
+		list_del(&cpuctx->sched_cb_entry);
+}
+
+
+void perf_sched_cb_inc(struct pmu *pmu)
+{
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+
+	if (!cpuctx->sched_cb_usage++)
+		list_add(&cpuctx->sched_cb_entry, this_cpu_ptr(&sched_cb_list));
+
+	this_cpu_inc(perf_sched_cb_usages);
+}
+
+/*
+ * This function provides the context switch callback to the lower code
+ * layer. It is invoked ONLY when the context switch callback is enabled.
+ *
+ * This callback is relevant even to per-cpu events; for example multi event
+ * PEBS requires this to provide PID/TID information. This requires we flush
+ * all queued PEBS records before we context switch to a new task.
+ */
+static void __perf_pmu_sched_task(struct perf_cpu_context *cpuctx, bool sched_in)
+{
+	struct pmu *pmu;
+
+	pmu = cpuctx->ctx.pmu; /* software PMUs will not have sched_task */
+
+	if (WARN_ON_ONCE(!pmu->sched_task))
+		return;
+
+	perf_ctx_lock(cpuctx, cpuctx->task_ctx);
+	perf_pmu_disable(pmu);
+
+	pmu->sched_task(cpuctx->task_ctx, sched_in);
+
+	perf_pmu_enable(pmu);
+	perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
+}
+
+static void perf_pmu_sched_task(struct task_struct *prev,
+				struct task_struct *next,
+				bool sched_in)
+{
+	struct perf_cpu_context *cpuctx;
+
+	if (prev == next)
+		return;
+
+	list_for_each_entry(cpuctx, this_cpu_ptr(&sched_cb_list), sched_cb_entry) {
+		/* will be handled in perf_event_context_sched_in/out */
+		if (cpuctx->task_ctx)
+			continue;
+
+		__perf_pmu_sched_task(cpuctx, sched_in);
+	}
+}
+
+static void perf_event_switch(struct task_struct *task,
+			      struct task_struct *next_prev, bool sched_in);
+
+#define for_each_task_context_nr(ctxn)					\
+	for ((ctxn) = 0; (ctxn) < perf_nr_task_contexts; (ctxn)++)
+
+/*
+ * Called from scheduler to remove the events of the current task,
+ * with interrupts disabled.
+ *
+ * We stop each event and update the event value in event->count.
+ *
+ * This does not protect us against NMI, but disable()
+ * sets the disabled bit in the control field of event _before_
+ * accessing the event control register. If a NMI hits, then it will
+ * not restart the event.
+ */
+void __perf_event_task_sched_out(struct task_struct *task,
+				 struct task_struct *next)
+{
+	int ctxn;
+
+	if (__this_cpu_read(perf_sched_cb_usages))
+		perf_pmu_sched_task(task, next, false);
+
+	if (atomic_read(&nr_switch_events))
+		perf_event_switch(task, next, false);
+
+	for_each_task_context_nr(ctxn)
+		perf_event_context_sched_out(task, ctxn, next);
+
+	/*
+	 * if cgroup events exist on this CPU, then we need
+	 * to check if we have to switch out PMU state.
+	 * cgroup event are system-wide mode only
+	 */
+	if (atomic_read(this_cpu_ptr(&perf_cgroup_events)))
+		perf_cgroup_switch(next);
+}
+
+/*
+ * Called with IRQs disabled
+ */
+static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
+			      enum event_type_t event_type)
+{
+	ctx_sched_out(&cpuctx->ctx, cpuctx, event_type);
+}
+
+static bool perf_less_group_idx(const void *l, const void *r)
+{
+	const struct perf_event *le = *(const struct perf_event **)l;
+	const struct perf_event *re = *(const struct perf_event **)r;
+
+	return le->group_index < re->group_index;
+}
+
+static void swap_ptr(void *l, void *r)
+{
+	void **lp = l, **rp = r;
+
+	swap(*lp, *rp);
+}
+
+static const struct min_heap_callbacks perf_min_heap = {
+	.elem_size = sizeof(struct perf_event *),
+	.less = perf_less_group_idx,
+	.swp = swap_ptr,
+};
+
+static void __heap_add(struct min_heap *heap, struct perf_event *event)
+{
+	struct perf_event **itrs = heap->data;
+
+	if (event) {
+		itrs[heap->nr] = event;
+		heap->nr++;
+	}
+}
+
+static noinline int visit_groups_merge(struct perf_cpu_context *cpuctx,
+				struct perf_event_groups *groups, int cpu,
+				int (*func)(struct perf_event *, void *),
+				void *data)
+{
+#ifdef CONFIG_CGROUP_PERF
+	struct cgroup_subsys_state *css = NULL;
+#endif
+	/* Space for per CPU and/or any CPU event iterators. */
+	struct perf_event *itrs[2];
+	struct min_heap event_heap;
+	struct perf_event **evt;
+	int ret;
+
+	if (cpuctx) {
+		event_heap = (struct min_heap){
+			.data = cpuctx->heap,
+			.nr = 0,
+			.size = cpuctx->heap_size,
+		};
+
+		lockdep_assert_held(&cpuctx->ctx.lock);
+
+#ifdef CONFIG_CGROUP_PERF
+		if (cpuctx->cgrp)
+			css = &cpuctx->cgrp->css;
+#endif
+	} else {
+		event_heap = (struct min_heap){
+			.data = itrs,
+			.nr = 0,
+			.size = ARRAY_SIZE(itrs),
+		};
+		/* Events not within a CPU context may be on any CPU. */
+		__heap_add(&event_heap, perf_event_groups_first(groups, -1, NULL));
+	}
+	evt = event_heap.data;
+
+	__heap_add(&event_heap, perf_event_groups_first(groups, cpu, NULL));
+
+#ifdef CONFIG_CGROUP_PERF
+	for (; css; css = css->parent)
+		__heap_add(&event_heap, perf_event_groups_first(groups, cpu, css->cgroup));
+#endif
+
+	min_heapify_all(&event_heap, &perf_min_heap);
+
+	while (event_heap.nr) {
+		ret = func(*evt, data);
+		if (ret)
+			return ret;
+
+		*evt = perf_event_groups_next(*evt);
+		if (*evt)
+			min_heapify(&event_heap, 0, &perf_min_heap);
+		else
+			min_heap_pop(&event_heap, &perf_min_heap);
+	}
+
+	return 0;
+}
+
+/*
+ * Because the userpage is strictly per-event (there is no concept of context,
+ * so there cannot be a context indirection), every userpage must be updated
+ * when context time starts :-(
+ *
+ * IOW, we must not miss EVENT_TIME edges.
+ */
+static inline bool event_update_userpage(struct perf_event *event)
+{
+	if (likely(!atomic_read(&event->mmap_count)))
+		return false;
+
+	perf_event_update_time(event);
+	perf_event_update_userpage(event);
+
+	return true;
+}
+
+static inline void group_update_userpage(struct perf_event *group_event)
+{
+	struct perf_event *event;
+
+	if (!event_update_userpage(group_event))
+		return;
+
+	for_each_sibling_event(event, group_event)
+		event_update_userpage(event);
+}
+
+static int merge_sched_in(struct perf_event *event, void *data)
+{
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	int *can_add_hw = data;
+
+	if (event->state <= PERF_EVENT_STATE_OFF)
+		return 0;
+
+	if (!event_filter_match(event))
+		return 0;
+
+	if (group_can_go_on(event, cpuctx, *can_add_hw)) {
+		if (!group_sched_in(event, cpuctx, ctx))
+			list_add_tail(&event->active_list, get_event_list(event));
+	}
+
+	if (event->state == PERF_EVENT_STATE_INACTIVE) {
+		*can_add_hw = 0;
+		if (event->attr.pinned) {
+			perf_cgroup_event_disable(event, ctx);
+			perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
+		} else {
+			ctx->rotate_necessary = 1;
+			perf_mux_hrtimer_restart(cpuctx);
+			group_update_userpage(event);
+		}
+	}
+
+	return 0;
+}
+
+static void
+ctx_pinned_sched_in(struct perf_event_context *ctx,
+		    struct perf_cpu_context *cpuctx)
+{
+	int can_add_hw = 1;
+
+	if (ctx != &cpuctx->ctx)
+		cpuctx = NULL;
+
+	visit_groups_merge(cpuctx, &ctx->pinned_groups,
+			   smp_processor_id(),
+			   merge_sched_in, &can_add_hw);
+}
+
+static void
+ctx_flexible_sched_in(struct perf_event_context *ctx,
+		      struct perf_cpu_context *cpuctx)
+{
+	int can_add_hw = 1;
+
+	if (ctx != &cpuctx->ctx)
+		cpuctx = NULL;
+
+	visit_groups_merge(cpuctx, &ctx->flexible_groups,
+			   smp_processor_id(),
+			   merge_sched_in, &can_add_hw);
+}
+
+static void
+ctx_sched_in(struct perf_event_context *ctx,
+	     struct perf_cpu_context *cpuctx,
+	     enum event_type_t event_type)
+{
+	int is_active = ctx->is_active;
+
+	lockdep_assert_held(&ctx->lock);
+
+	if (likely(!ctx->nr_events))
+		return;
+
+	if (!(is_active & EVENT_TIME)) {
+		/* start ctx time */
+		__update_context_time(ctx, false);
+		perf_cgroup_set_timestamp(cpuctx);
+		/*
+		 * CPU-release for the below ->is_active store,
+		 * see __load_acquire() in perf_event_time_now()
+		 */
+		barrier();
+	}
+
+	ctx->is_active |= (event_type | EVENT_TIME);
+	if (ctx->task) {
+		if (!is_active)
+			cpuctx->task_ctx = ctx;
+		else
+			WARN_ON_ONCE(cpuctx->task_ctx != ctx);
+	}
+
+	is_active ^= ctx->is_active; /* changed bits */
+
+	/*
+	 * First go through the list and put on any pinned groups
+	 * in order to give them the best chance of going on.
+	 */
+	if (is_active & EVENT_PINNED)
+		ctx_pinned_sched_in(ctx, cpuctx);
+
+	/* Then walk through the lower prio flexible groups */
+	if (is_active & EVENT_FLEXIBLE)
+		ctx_flexible_sched_in(ctx, cpuctx);
+}
+
+static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
+			     enum event_type_t event_type)
+{
+	struct perf_event_context *ctx = &cpuctx->ctx;
+
+	ctx_sched_in(ctx, cpuctx, event_type);
+}
+
+static void perf_event_context_sched_in(struct perf_event_context *ctx,
+					struct task_struct *task)
+{
+	struct perf_cpu_context *cpuctx;
+	struct pmu *pmu;
+
+	cpuctx = __get_cpu_context(ctx);
+
+	/*
+	 * HACK: for HETEROGENEOUS the task context might have switched to a
+	 * different PMU, force (re)set the context,
+	 */
+	pmu = ctx->pmu = cpuctx->ctx.pmu;
+
+	if (cpuctx->task_ctx == ctx) {
+		if (cpuctx->sched_cb_usage)
+			__perf_pmu_sched_task(cpuctx, true);
+		return;
+	}
+
+	perf_ctx_lock(cpuctx, ctx);
+	/*
+	 * We must check ctx->nr_events while holding ctx->lock, such
+	 * that we serialize against perf_install_in_context().
+	 */
+	if (!ctx->nr_events)
+		goto unlock;
+
+	perf_pmu_disable(pmu);
+	/*
+	 * We want to keep the following priority order:
+	 * cpu pinned (that don't need to move), task pinned,
+	 * cpu flexible, task flexible.
+	 *
+	 * However, if task's ctx is not carrying any pinned
+	 * events, no need to flip the cpuctx's events around.
+	 */
+	if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree))
+		cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+	perf_event_sched_in(cpuctx, ctx);
+
+	if (cpuctx->sched_cb_usage && pmu->sched_task)
+		pmu->sched_task(cpuctx->task_ctx, true);
+
+	perf_pmu_enable(pmu);
+
+unlock:
+	perf_ctx_unlock(cpuctx, ctx);
+}
+
+/*
+ * Called from scheduler to add the events of the current task
+ * with interrupts disabled.
+ *
+ * We restore the event value and then enable it.
+ *
+ * This does not protect us against NMI, but enable()
+ * sets the enabled bit in the control field of event _before_
+ * accessing the event control register. If a NMI hits, then it will
+ * keep the event running.
+ */
+void __perf_event_task_sched_in(struct task_struct *prev,
+				struct task_struct *task)
+{
+	struct perf_event_context *ctx;
+	int ctxn;
+
+	for_each_task_context_nr(ctxn) {
+		ctx = task->perf_event_ctxp[ctxn];
+		if (likely(!ctx))
+			continue;
+
+		perf_event_context_sched_in(ctx, task);
+	}
+
+	if (atomic_read(&nr_switch_events))
+		perf_event_switch(task, prev, true);
+
+	if (__this_cpu_read(perf_sched_cb_usages))
+		perf_pmu_sched_task(prev, task, true);
+}
+
+static u64 perf_calculate_period(struct perf_event *event, u64 nsec, u64 count)
+{
+	u64 frequency = event->attr.sample_freq;
+	u64 sec = NSEC_PER_SEC;
+	u64 divisor, dividend;
+
+	int count_fls, nsec_fls, frequency_fls, sec_fls;
+
+	count_fls = fls64(count);
+	nsec_fls = fls64(nsec);
+	frequency_fls = fls64(frequency);
+	sec_fls = 30;
+
+	/*
+	 * We got @count in @nsec, with a target of sample_freq HZ
+	 * the target period becomes:
+	 *
+	 *             @count * 10^9
+	 * period = -------------------
+	 *          @nsec * sample_freq
+	 *
+	 */
+
+	/*
+	 * Reduce accuracy by one bit such that @a and @b converge
+	 * to a similar magnitude.
+	 */
+#define REDUCE_FLS(a, b)		\
+do {					\
+	if (a##_fls > b##_fls) {	\
+		a >>= 1;		\
+		a##_fls--;		\
+	} else {			\
+		b >>= 1;		\
+		b##_fls--;		\
+	}				\
+} while (0)
+
+	/*
+	 * Reduce accuracy until either term fits in a u64, then proceed with
+	 * the other, so that finally we can do a u64/u64 division.
+	 */
+	while (count_fls + sec_fls > 64 && nsec_fls + frequency_fls > 64) {
+		REDUCE_FLS(nsec, frequency);
+		REDUCE_FLS(sec, count);
+	}
+
+	if (count_fls + sec_fls > 64) {
+		divisor = nsec * frequency;
+
+		while (count_fls + sec_fls > 64) {
+			REDUCE_FLS(count, sec);
+			divisor >>= 1;
+		}
+
+		dividend = count * sec;
+	} else {
+		dividend = count * sec;
+
+		while (nsec_fls + frequency_fls > 64) {
+			REDUCE_FLS(nsec, frequency);
+			dividend >>= 1;
+		}
+
+		divisor = nsec * frequency;
+	}
+
+	if (!divisor)
+		return dividend;
+
+	return div64_u64(dividend, divisor);
+}
+
+static DEFINE_PER_CPU(int, perf_throttled_count);
+static DEFINE_PER_CPU(u64, perf_throttled_seq);
+
+static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count, bool disable)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	s64 period, sample_period;
+	s64 delta;
+
+	period = perf_calculate_period(event, nsec, count);
+
+	delta = (s64)(period - hwc->sample_period);
+	delta = (delta + 7) / 8; /* low pass filter */
+
+	sample_period = hwc->sample_period + delta;
+
+	if (!sample_period)
+		sample_period = 1;
+
+	hwc->sample_period = sample_period;
+
+	if (local64_read(&hwc->period_left) > 8*sample_period) {
+		if (disable)
+			event->pmu->stop(event, PERF_EF_UPDATE);
+
+		local64_set(&hwc->period_left, 0);
+
+		if (disable)
+			event->pmu->start(event, PERF_EF_RELOAD);
+	}
+}
+
+/*
+ * combine freq adjustment with unthrottling to avoid two passes over the
+ * events. At the same time, make sure, having freq events does not change
+ * the rate of unthrottling as that would introduce bias.
+ */
+static void perf_adjust_freq_unthr_context(struct perf_event_context *ctx,
+					   int needs_unthr)
+{
+	struct perf_event *event;
+	struct hw_perf_event *hwc;
+	u64 now, period = TICK_NSEC;
+	s64 delta;
+
+	/*
+	 * only need to iterate over all events iff:
+	 * - context have events in frequency mode (needs freq adjust)
+	 * - there are events to unthrottle on this cpu
+	 */
+	if (!(ctx->nr_freq || needs_unthr))
+		return;
+
+	raw_spin_lock(&ctx->lock);
+	perf_pmu_disable(ctx->pmu);
+
+	list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+		if (event->state != PERF_EVENT_STATE_ACTIVE)
+			continue;
+
+		if (!event_filter_match(event))
+			continue;
+
+		perf_pmu_disable(event->pmu);
+
+		hwc = &event->hw;
+
+		if (hwc->interrupts == MAX_INTERRUPTS) {
+			hwc->interrupts = 0;
+			perf_log_throttle(event, 1);
+			event->pmu->start(event, 0);
+		}
+
+		if (!event->attr.freq || !event->attr.sample_freq)
+			goto next;
+
+		/*
+		 * stop the event and update event->count
+		 */
+		event->pmu->stop(event, PERF_EF_UPDATE);
+
+		now = local64_read(&event->count);
+		delta = now - hwc->freq_count_stamp;
+		hwc->freq_count_stamp = now;
+
+		/*
+		 * restart the event
+		 * reload only if value has changed
+		 * we have stopped the event so tell that
+		 * to perf_adjust_period() to avoid stopping it
+		 * twice.
+		 */
+		if (delta > 0)
+			perf_adjust_period(event, period, delta, false);
+
+		event->pmu->start(event, delta > 0 ? PERF_EF_RELOAD : 0);
+	next:
+		perf_pmu_enable(event->pmu);
+	}
+
+	perf_pmu_enable(ctx->pmu);
+	raw_spin_unlock(&ctx->lock);
+}
+
+/*
+ * Move @event to the tail of the @ctx's elegible events.
+ */
+static void rotate_ctx(struct perf_event_context *ctx, struct perf_event *event)
+{
+	/*
+	 * Rotate the first entry last of non-pinned groups. Rotation might be
+	 * disabled by the inheritance code.
+	 */
+	if (ctx->rotate_disable)
+		return;
+
+	perf_event_groups_delete(&ctx->flexible_groups, event);
+	perf_event_groups_insert(&ctx->flexible_groups, event);
+}
+
+/* pick an event from the flexible_groups to rotate */
+static inline struct perf_event *
+ctx_event_to_rotate(struct perf_event_context *ctx)
+{
+	struct perf_event *event;
+
+	/* pick the first active flexible event */
+	event = list_first_entry_or_null(&ctx->flexible_active,
+					 struct perf_event, active_list);
+
+	/* if no active flexible event, pick the first event */
+	if (!event) {
+		event = rb_entry_safe(rb_first(&ctx->flexible_groups.tree),
+				      typeof(*event), group_node);
+	}
+
+	/*
+	 * Unconditionally clear rotate_necessary; if ctx_flexible_sched_in()
+	 * finds there are unschedulable events, it will set it again.
+	 */
+	ctx->rotate_necessary = 0;
+
+	return event;
+}
+
+static bool perf_rotate_context(struct perf_cpu_context *cpuctx)
+{
+	struct perf_event *cpu_event = NULL, *task_event = NULL;
+	struct perf_event_context *task_ctx = NULL;
+	int cpu_rotate, task_rotate;
+
+	/*
+	 * Since we run this from IRQ context, nobody can install new
+	 * events, thus the event count values are stable.
+	 */
+
+	cpu_rotate = cpuctx->ctx.rotate_necessary;
+	task_ctx = cpuctx->task_ctx;
+	task_rotate = task_ctx ? task_ctx->rotate_necessary : 0;
+
+	if (!(cpu_rotate || task_rotate))
+		return false;
+
+	perf_ctx_lock(cpuctx, cpuctx->task_ctx);
+	perf_pmu_disable(cpuctx->ctx.pmu);
+
+	if (task_rotate)
+		task_event = ctx_event_to_rotate(task_ctx);
+	if (cpu_rotate)
+		cpu_event = ctx_event_to_rotate(&cpuctx->ctx);
+
+	/*
+	 * As per the order given at ctx_resched() first 'pop' task flexible
+	 * and then, if needed CPU flexible.
+	 */
+	if (task_event || (task_ctx && cpu_event))
+		ctx_sched_out(task_ctx, cpuctx, EVENT_FLEXIBLE);
+	if (cpu_event)
+		cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+
+	if (task_event)
+		rotate_ctx(task_ctx, task_event);
+	if (cpu_event)
+		rotate_ctx(&cpuctx->ctx, cpu_event);
+
+	perf_event_sched_in(cpuctx, task_ctx);
+
+	perf_pmu_enable(cpuctx->ctx.pmu);
+	perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
+
+	return true;
+}
+
+void perf_event_task_tick(void)
+{
+	struct list_head *head = this_cpu_ptr(&active_ctx_list);
+	struct perf_event_context *ctx, *tmp;
+	int throttled;
+
+	lockdep_assert_irqs_disabled();
+
+	__this_cpu_inc(perf_throttled_seq);
+	throttled = __this_cpu_xchg(perf_throttled_count, 0);
+	tick_dep_clear_cpu(smp_processor_id(), TICK_DEP_BIT_PERF_EVENTS);
+
+	list_for_each_entry_safe(ctx, tmp, head, active_ctx_list)
+		perf_adjust_freq_unthr_context(ctx, throttled);
+}
+
+static int event_enable_on_exec(struct perf_event *event,
+				struct perf_event_context *ctx)
+{
+	if (!event->attr.enable_on_exec)
+		return 0;
+
+	event->attr.enable_on_exec = 0;
+	if (event->state >= PERF_EVENT_STATE_INACTIVE)
+		return 0;
+
+	perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE);
+
+	return 1;
+}
+
+/*
+ * Enable all of a task's events that have been marked enable-on-exec.
+ * This expects task == current.
+ */
+static void perf_event_enable_on_exec(int ctxn)
+{
+	struct perf_event_context *ctx, *clone_ctx = NULL;
+	enum event_type_t event_type = 0;
+	struct perf_cpu_context *cpuctx;
+	struct perf_event *event;
+	unsigned long flags;
+	int enabled = 0;
+
+	local_irq_save(flags);
+	ctx = current->perf_event_ctxp[ctxn];
+	if (!ctx || !ctx->nr_events)
+		goto out;
+
+	cpuctx = __get_cpu_context(ctx);
+	perf_ctx_lock(cpuctx, ctx);
+	ctx_sched_out(ctx, cpuctx, EVENT_TIME);
+	list_for_each_entry(event, &ctx->event_list, event_entry) {
+		enabled |= event_enable_on_exec(event, ctx);
+		event_type |= get_event_type(event);
+	}
+
+	/*
+	 * Unclone and reschedule this context if we enabled any event.
+	 */
+	if (enabled) {
+		clone_ctx = unclone_ctx(ctx);
+		ctx_resched(cpuctx, ctx, event_type);
+	} else {
+		ctx_sched_in(ctx, cpuctx, EVENT_TIME);
+	}
+	perf_ctx_unlock(cpuctx, ctx);
+
+out:
+	local_irq_restore(flags);
+
+	if (clone_ctx)
+		put_ctx(clone_ctx);
+}
+
+static void perf_remove_from_owner(struct perf_event *event);
+static void perf_event_exit_event(struct perf_event *event,
+				  struct perf_event_context *ctx);
+
+/*
+ * Removes all events from the current task that have been marked
+ * remove-on-exec, and feeds their values back to parent events.
+ */
+static void perf_event_remove_on_exec(int ctxn)
+{
+	struct perf_event_context *ctx, *clone_ctx = NULL;
+	struct perf_event *event, *next;
+	unsigned long flags;
+	bool modified = false;
+
+	ctx = perf_pin_task_context(current, ctxn);
+	if (!ctx)
+		return;
+
+	mutex_lock(&ctx->mutex);
+
+	if (WARN_ON_ONCE(ctx->task != current))
+		goto unlock;
+
+	list_for_each_entry_safe(event, next, &ctx->event_list, event_entry) {
+		if (!event->attr.remove_on_exec)
+			continue;
+
+		if (!is_kernel_event(event))
+			perf_remove_from_owner(event);
+
+		modified = true;
+
+		perf_event_exit_event(event, ctx);
+	}
+
+	raw_spin_lock_irqsave(&ctx->lock, flags);
+	if (modified)
+		clone_ctx = unclone_ctx(ctx);
+	--ctx->pin_count;
+	raw_spin_unlock_irqrestore(&ctx->lock, flags);
+
+unlock:
+	mutex_unlock(&ctx->mutex);
+
+	put_ctx(ctx);
+	if (clone_ctx)
+		put_ctx(clone_ctx);
+}
+
+struct perf_read_data {
+	struct perf_event *event;
+	bool group;
+	int ret;
+};
+
+static int __perf_event_read_cpu(struct perf_event *event, int event_cpu)
+{
+	u16 local_pkg, event_pkg;
+
+	if (event->group_caps & PERF_EV_CAP_READ_ACTIVE_PKG) {
+		int local_cpu = smp_processor_id();
+
+		event_pkg = topology_physical_package_id(event_cpu);
+		local_pkg = topology_physical_package_id(local_cpu);
+
+		if (event_pkg == local_pkg)
+			return local_cpu;
+	}
+
+	return event_cpu;
+}
+
+/*
+ * Cross CPU call to read the hardware event
+ */
+static void __perf_event_read(void *info)
+{
+	struct perf_read_data *data = info;
+	struct perf_event *sub, *event = data->event;
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct pmu *pmu = event->pmu;
+
+	/*
+	 * If this is a task context, we need to check whether it is
+	 * the current task context of this cpu.  If not it has been
+	 * scheduled out before the smp call arrived.  In that case
+	 * event->count would have been updated to a recent sample
+	 * when the event was scheduled out.
+	 */
+	if (ctx->task && cpuctx->task_ctx != ctx)
+		return;
+
+	raw_spin_lock(&ctx->lock);
+	if (ctx->is_active & EVENT_TIME) {
+		update_context_time(ctx);
+		update_cgrp_time_from_event(event);
+	}
+
+	perf_event_update_time(event);
+	if (data->group)
+		perf_event_update_sibling_time(event);
+
+	if (event->state != PERF_EVENT_STATE_ACTIVE)
+		goto unlock;
+
+	if (!data->group) {
+		pmu->read(event);
+		data->ret = 0;
+		goto unlock;
+	}
+
+	pmu->start_txn(pmu, PERF_PMU_TXN_READ);
+
+	pmu->read(event);
+
+	for_each_sibling_event(sub, event) {
+		if (sub->state == PERF_EVENT_STATE_ACTIVE) {
+			/*
+			 * Use sibling's PMU rather than @event's since
+			 * sibling could be on different (eg: software) PMU.
+			 */
+			sub->pmu->read(sub);
+		}
+	}
+
+	data->ret = pmu->commit_txn(pmu);
+
+unlock:
+	raw_spin_unlock(&ctx->lock);
+}
+
+static inline u64 perf_event_count(struct perf_event *event)
+{
+	return local64_read(&event->count) + atomic64_read(&event->child_count);
+}
+
+static void calc_timer_values(struct perf_event *event,
+				u64 *now,
+				u64 *enabled,
+				u64 *running)
+{
+	u64 ctx_time;
+
+	*now = perf_clock();
+	ctx_time = perf_event_time_now(event, *now);
+	__perf_update_times(event, ctx_time, enabled, running);
+}
+
+/*
+ * NMI-safe method to read a local event, that is an event that
+ * is:
+ *   - either for the current task, or for this CPU
+ *   - does not have inherit set, for inherited task events
+ *     will not be local and we cannot read them atomically
+ *   - must not have a pmu::count method
+ */
+int perf_event_read_local(struct perf_event *event, u64 *value,
+			  u64 *enabled, u64 *running)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	/*
+	 * Disabling interrupts avoids all counter scheduling (context
+	 * switches, timer based rotation and IPIs).
+	 */
+	local_irq_save(flags);
+
+	/*
+	 * It must not be an event with inherit set, we cannot read
+	 * all child counters from atomic context.
+	 */
+	if (event->attr.inherit) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+
+	/* If this is a per-task event, it must be for current */
+	if ((event->attach_state & PERF_ATTACH_TASK) &&
+	    event->hw.target != current) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* If this is a per-CPU event, it must be for this CPU */
+	if (!(event->attach_state & PERF_ATTACH_TASK) &&
+	    event->cpu != smp_processor_id()) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* If this is a pinned event it must be running on this CPU */
+	if (event->attr.pinned && event->oncpu != smp_processor_id()) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	/*
+	 * If the event is currently on this CPU, its either a per-task event,
+	 * or local to this CPU. Furthermore it means its ACTIVE (otherwise
+	 * oncpu == -1).
+	 */
+	if (event->oncpu == smp_processor_id())
+		event->pmu->read(event);
+
+	*value = local64_read(&event->count);
+	if (enabled || running) {
+		u64 __enabled, __running, __now;
+
+		calc_timer_values(event, &__now, &__enabled, &__running);
+		if (enabled)
+			*enabled = __enabled;
+		if (running)
+			*running = __running;
+	}
+out:
+	local_irq_restore(flags);
+
+	return ret;
+}
+
+static int perf_event_read(struct perf_event *event, bool group)
+{
+	enum perf_event_state state = READ_ONCE(event->state);
+	int event_cpu, ret = 0;
+
+	/*
+	 * If event is enabled and currently active on a CPU, update the
+	 * value in the event structure:
+	 */
+again:
+	if (state == PERF_EVENT_STATE_ACTIVE) {
+		struct perf_read_data data;
+
+		/*
+		 * Orders the ->state and ->oncpu loads such that if we see
+		 * ACTIVE we must also see the right ->oncpu.
+		 *
+		 * Matches the smp_wmb() from event_sched_in().
+		 */
+		smp_rmb();
+
+		event_cpu = READ_ONCE(event->oncpu);
+		if ((unsigned)event_cpu >= nr_cpu_ids)
+			return 0;
+
+		data = (struct perf_read_data){
+			.event = event,
+			.group = group,
+			.ret = 0,
+		};
+
+		preempt_disable();
+		event_cpu = __perf_event_read_cpu(event, event_cpu);
+
+		/*
+		 * Purposely ignore the smp_call_function_single() return
+		 * value.
+		 *
+		 * If event_cpu isn't a valid CPU it means the event got
+		 * scheduled out and that will have updated the event count.
+		 *
+		 * Therefore, either way, we'll have an up-to-date event count
+		 * after this.
+		 */
+		(void)smp_call_function_single(event_cpu, __perf_event_read, &data, 1);
+		preempt_enable();
+		ret = data.ret;
+
+	} else if (state == PERF_EVENT_STATE_INACTIVE) {
+		struct perf_event_context *ctx = event->ctx;
+		unsigned long flags;
+
+		raw_spin_lock_irqsave(&ctx->lock, flags);
+		state = event->state;
+		if (state != PERF_EVENT_STATE_INACTIVE) {
+			raw_spin_unlock_irqrestore(&ctx->lock, flags);
+			goto again;
+		}
+
+		/*
+		 * May read while context is not active (e.g., thread is
+		 * blocked), in that case we cannot update context time
+		 */
+		if (ctx->is_active & EVENT_TIME) {
+			update_context_time(ctx);
+			update_cgrp_time_from_event(event);
+		}
+
+		perf_event_update_time(event);
+		if (group)
+			perf_event_update_sibling_time(event);
+		raw_spin_unlock_irqrestore(&ctx->lock, flags);
+	}
+
+	return ret;
+}
+
+/*
+ * Initialize the perf_event context in a task_struct:
+ */
+static void __perf_event_init_context(struct perf_event_context *ctx)
+{
+	raw_spin_lock_init(&ctx->lock);
+	mutex_init(&ctx->mutex);
+	INIT_LIST_HEAD(&ctx->active_ctx_list);
+	perf_event_groups_init(&ctx->pinned_groups);
+	perf_event_groups_init(&ctx->flexible_groups);
+	INIT_LIST_HEAD(&ctx->event_list);
+	INIT_LIST_HEAD(&ctx->pinned_active);
+	INIT_LIST_HEAD(&ctx->flexible_active);
+	refcount_set(&ctx->refcount, 1);
+}
+
+static struct perf_event_context *
+alloc_perf_context(struct pmu *pmu, struct task_struct *task)
+{
+	struct perf_event_context *ctx;
+
+	ctx = kzalloc(sizeof(struct perf_event_context), GFP_KERNEL);
+	if (!ctx)
+		return NULL;
+
+	__perf_event_init_context(ctx);
+	if (task)
+		ctx->task = get_task_struct(task);
+	ctx->pmu = pmu;
+
+	return ctx;
+}
+
+static struct task_struct *
+find_lively_task_by_vpid(pid_t vpid)
+{
+	struct task_struct *task;
+
+	rcu_read_lock();
+	if (!vpid)
+		task = current;
+	else
+		task = find_task_by_vpid(vpid);
+	if (task)
+		get_task_struct(task);
+	rcu_read_unlock();
+
+	if (!task)
+		return ERR_PTR(-ESRCH);
+
+	return task;
+}
+
+/*
+ * Returns a matching context with refcount and pincount.
+ */
+static struct perf_event_context *
+find_get_context(struct pmu *pmu, struct task_struct *task,
+		struct perf_event *event)
+{
+	struct perf_event_context *ctx, *clone_ctx = NULL;
+	struct perf_cpu_context *cpuctx;
+	void *task_ctx_data = NULL;
+	unsigned long flags;
+	int ctxn, err;
+	int cpu = event->cpu;
+
+	if (!task) {
+		/* Must be root to operate on a CPU event: */
+		err = perf_allow_cpu(&event->attr);
+		if (err)
+			return ERR_PTR(err);
+
+		cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+		ctx = &cpuctx->ctx;
+		get_ctx(ctx);
+		raw_spin_lock_irqsave(&ctx->lock, flags);
+		++ctx->pin_count;
+		raw_spin_unlock_irqrestore(&ctx->lock, flags);
+
+		return ctx;
+	}
+
+	err = -EINVAL;
+	ctxn = pmu->task_ctx_nr;
+	if (ctxn < 0)
+		goto errout;
+
+	if (event->attach_state & PERF_ATTACH_TASK_DATA) {
+		task_ctx_data = alloc_task_ctx_data(pmu);
+		if (!task_ctx_data) {
+			err = -ENOMEM;
+			goto errout;
+		}
+	}
+
+retry:
+	ctx = perf_lock_task_context(task, ctxn, &flags);
+	if (ctx) {
+		clone_ctx = unclone_ctx(ctx);
+		++ctx->pin_count;
+
+		if (task_ctx_data && !ctx->task_ctx_data) {
+			ctx->task_ctx_data = task_ctx_data;
+			task_ctx_data = NULL;
+		}
+		raw_spin_unlock_irqrestore(&ctx->lock, flags);
+
+		if (clone_ctx)
+			put_ctx(clone_ctx);
+	} else {
+		ctx = alloc_perf_context(pmu, task);
+		err = -ENOMEM;
+		if (!ctx)
+			goto errout;
+
+		if (task_ctx_data) {
+			ctx->task_ctx_data = task_ctx_data;
+			task_ctx_data = NULL;
+		}
+
+		err = 0;
+		mutex_lock(&task->perf_event_mutex);
+		/*
+		 * If it has already passed perf_event_exit_task().
+		 * we must see PF_EXITING, it takes this mutex too.
+		 */
+		if (task->flags & PF_EXITING)
+			err = -ESRCH;
+		else if (task->perf_event_ctxp[ctxn])
+			err = -EAGAIN;
+		else {
+			get_ctx(ctx);
+			++ctx->pin_count;
+			rcu_assign_pointer(task->perf_event_ctxp[ctxn], ctx);
+		}
+		mutex_unlock(&task->perf_event_mutex);
+
+		if (unlikely(err)) {
+			put_ctx(ctx);
+
+			if (err == -EAGAIN)
+				goto retry;
+			goto errout;
+		}
+	}
+
+	free_task_ctx_data(pmu, task_ctx_data);
+	return ctx;
+
+errout:
+	free_task_ctx_data(pmu, task_ctx_data);
+	return ERR_PTR(err);
+}
+
+static void perf_event_free_filter(struct perf_event *event);
+
+static void free_event_rcu(struct rcu_head *head)
+{
+	struct perf_event *event;
+
+	event = container_of(head, struct perf_event, rcu_head);
+	if (event->ns)
+		put_pid_ns(event->ns);
+	perf_event_free_filter(event);
+	kmem_cache_free(perf_event_cache, event);
+}
+
+static void ring_buffer_attach(struct perf_event *event,
+			       struct perf_buffer *rb);
+
+static void detach_sb_event(struct perf_event *event)
+{
+	struct pmu_event_list *pel = per_cpu_ptr(&pmu_sb_events, event->cpu);
+
+	raw_spin_lock(&pel->lock);
+	list_del_rcu(&event->sb_list);
+	raw_spin_unlock(&pel->lock);
+}
+
+static bool is_sb_event(struct perf_event *event)
+{
+	struct perf_event_attr *attr = &event->attr;
+
+	if (event->parent)
+		return false;
+
+	if (event->attach_state & PERF_ATTACH_TASK)
+		return false;
+
+	if (attr->mmap || attr->mmap_data || attr->mmap2 ||
+	    attr->comm || attr->comm_exec ||
+	    attr->task || attr->ksymbol ||
+	    attr->context_switch || attr->text_poke ||
+	    attr->bpf_event)
+		return true;
+	return false;
+}
+
+static void unaccount_pmu_sb_event(struct perf_event *event)
+{
+	if (is_sb_event(event))
+		detach_sb_event(event);
+}
+
+static void unaccount_event_cpu(struct perf_event *event, int cpu)
+{
+	if (event->parent)
+		return;
+
+	if (is_cgroup_event(event))
+		atomic_dec(&per_cpu(perf_cgroup_events, cpu));
+}
+
+#ifdef CONFIG_NO_HZ_FULL
+static DEFINE_SPINLOCK(nr_freq_lock);
+#endif
+
+static void unaccount_freq_event_nohz(void)
+{
+#ifdef CONFIG_NO_HZ_FULL
+	spin_lock(&nr_freq_lock);
+	if (atomic_dec_and_test(&nr_freq_events))
+		tick_nohz_dep_clear(TICK_DEP_BIT_PERF_EVENTS);
+	spin_unlock(&nr_freq_lock);
+#endif
+}
+
+static void unaccount_freq_event(void)
+{
+	if (tick_nohz_full_enabled())
+		unaccount_freq_event_nohz();
+	else
+		atomic_dec(&nr_freq_events);
+}
+
+static void unaccount_event(struct perf_event *event)
+{
+	bool dec = false;
+
+	if (event->parent)
+		return;
+
+	if (event->attach_state & (PERF_ATTACH_TASK | PERF_ATTACH_SCHED_CB))
+		dec = true;
+	if (event->attr.mmap || event->attr.mmap_data)
+		atomic_dec(&nr_mmap_events);
+	if (event->attr.build_id)
+		atomic_dec(&nr_build_id_events);
+	if (event->attr.comm)
+		atomic_dec(&nr_comm_events);
+	if (event->attr.namespaces)
+		atomic_dec(&nr_namespaces_events);
+	if (event->attr.cgroup)
+		atomic_dec(&nr_cgroup_events);
+	if (event->attr.task)
+		atomic_dec(&nr_task_events);
+	if (event->attr.freq)
+		unaccount_freq_event();
+	if (event->attr.context_switch) {
+		dec = true;
+		atomic_dec(&nr_switch_events);
+	}
+	if (is_cgroup_event(event))
+		dec = true;
+	if (has_branch_stack(event))
+		dec = true;
+	if (event->attr.ksymbol)
+		atomic_dec(&nr_ksymbol_events);
+	if (event->attr.bpf_event)
+		atomic_dec(&nr_bpf_events);
+	if (event->attr.text_poke)
+		atomic_dec(&nr_text_poke_events);
+
+	if (dec) {
+		if (!atomic_add_unless(&perf_sched_count, -1, 1))
+			schedule_delayed_work(&perf_sched_work, HZ);
+	}
+
+	unaccount_event_cpu(event, event->cpu);
+
+	unaccount_pmu_sb_event(event);
+}
+
+static void perf_sched_delayed(struct work_struct *work)
+{
+	mutex_lock(&perf_sched_mutex);
+	if (atomic_dec_and_test(&perf_sched_count))
+		static_branch_disable(&perf_sched_events);
+	mutex_unlock(&perf_sched_mutex);
+}
+
+/*
+ * The following implement mutual exclusion of events on "exclusive" pmus
+ * (PERF_PMU_CAP_EXCLUSIVE). Such pmus can only have one event scheduled
+ * at a time, so we disallow creating events that might conflict, namely:
+ *
+ *  1) cpu-wide events in the presence of per-task events,
+ *  2) per-task events in the presence of cpu-wide events,
+ *  3) two matching events on the same context.
+ *
+ * The former two cases are handled in the allocation path (perf_event_alloc(),
+ * _free_event()), the latter -- before the first perf_install_in_context().
+ */
+static int exclusive_event_init(struct perf_event *event)
+{
+	struct pmu *pmu = event->pmu;
+
+	if (!is_exclusive_pmu(pmu))
+		return 0;
+
+	/*
+	 * Prevent co-existence of per-task and cpu-wide events on the
+	 * same exclusive pmu.
+	 *
+	 * Negative pmu::exclusive_cnt means there are cpu-wide
+	 * events on this "exclusive" pmu, positive means there are
+	 * per-task events.
+	 *
+	 * Since this is called in perf_event_alloc() path, event::ctx
+	 * doesn't exist yet; it is, however, safe to use PERF_ATTACH_TASK
+	 * to mean "per-task event", because unlike other attach states it
+	 * never gets cleared.
+	 */
+	if (event->attach_state & PERF_ATTACH_TASK) {
+		if (!atomic_inc_unless_negative(&pmu->exclusive_cnt))
+			return -EBUSY;
+	} else {
+		if (!atomic_dec_unless_positive(&pmu->exclusive_cnt))
+			return -EBUSY;
+	}
+
+	return 0;
+}
+
+static void exclusive_event_destroy(struct perf_event *event)
+{
+	struct pmu *pmu = event->pmu;
+
+	if (!is_exclusive_pmu(pmu))
+		return;
+
+	/* see comment in exclusive_event_init() */
+	if (event->attach_state & PERF_ATTACH_TASK)
+		atomic_dec(&pmu->exclusive_cnt);
+	else
+		atomic_inc(&pmu->exclusive_cnt);
+}
+
+static bool exclusive_event_match(struct perf_event *e1, struct perf_event *e2)
+{
+	if ((e1->pmu == e2->pmu) &&
+	    (e1->cpu == e2->cpu ||
+	     e1->cpu == -1 ||
+	     e2->cpu == -1))
+		return true;
+	return false;
+}
+
+static bool exclusive_event_installable(struct perf_event *event,
+					struct perf_event_context *ctx)
+{
+	struct perf_event *iter_event;
+	struct pmu *pmu = event->pmu;
+
+	lockdep_assert_held(&ctx->mutex);
+
+	if (!is_exclusive_pmu(pmu))
+		return true;
+
+	list_for_each_entry(iter_event, &ctx->event_list, event_entry) {
+		if (exclusive_event_match(iter_event, event))
+			return false;
+	}
+
+	return true;
+}
+
+static void perf_addr_filters_splice(struct perf_event *event,
+				       struct list_head *head);
+
+static void _free_event(struct perf_event *event)
+{
+	irq_work_sync(&event->pending_irq);
+
+	unaccount_event(event);
+
+	security_perf_event_free(event);
+
+	if (event->rb) {
+		/*
+		 * Can happen when we close an event with re-directed output.
+		 *
+		 * Since we have a 0 refcount, perf_mmap_close() will skip
+		 * over us; possibly making our ring_buffer_put() the last.
+		 */
+		mutex_lock(&event->mmap_mutex);
+		ring_buffer_attach(event, NULL);
+		mutex_unlock(&event->mmap_mutex);
+	}
+
+	if (is_cgroup_event(event))
+		perf_detach_cgroup(event);
+
+	if (!event->parent) {
+		if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
+			put_callchain_buffers();
+	}
+
+	perf_event_free_bpf_prog(event);
+	perf_addr_filters_splice(event, NULL);
+	kfree(event->addr_filter_ranges);
+
+	if (event->destroy)
+		event->destroy(event);
+
+	/*
+	 * Must be after ->destroy(), due to uprobe_perf_close() using
+	 * hw.target.
+	 */
+	if (event->hw.target)
+		put_task_struct(event->hw.target);
+
+	/*
+	 * perf_event_free_task() relies on put_ctx() being 'last', in particular
+	 * all task references must be cleaned up.
+	 */
+	if (event->ctx)
+		put_ctx(event->ctx);
+
+	exclusive_event_destroy(event);
+	module_put(event->pmu->module);
+
+	call_rcu(&event->rcu_head, free_event_rcu);
+}
+
+/*
+ * Used to free events which have a known refcount of 1, such as in error paths
+ * where the event isn't exposed yet and inherited events.
+ */
+static void free_event(struct perf_event *event)
+{
+	if (WARN(atomic_long_cmpxchg(&event->refcount, 1, 0) != 1,
+				"unexpected event refcount: %ld; ptr=%p\n",
+				atomic_long_read(&event->refcount), event)) {
+		/* leak to avoid use-after-free */
+		return;
+	}
+
+	_free_event(event);
+}
+
+/*
+ * Remove user event from the owner task.
+ */
+static void perf_remove_from_owner(struct perf_event *event)
+{
+	struct task_struct *owner;
+
+	rcu_read_lock();
+	/*
+	 * Matches the smp_store_release() in perf_event_exit_task(). If we
+	 * observe !owner it means the list deletion is complete and we can
+	 * indeed free this event, otherwise we need to serialize on
+	 * owner->perf_event_mutex.
+	 */
+	owner = READ_ONCE(event->owner);
+	if (owner) {
+		/*
+		 * Since delayed_put_task_struct() also drops the last
+		 * task reference we can safely take a new reference
+		 * while holding the rcu_read_lock().
+		 */
+		get_task_struct(owner);
+	}
+	rcu_read_unlock();
+
+	if (owner) {
+		/*
+		 * If we're here through perf_event_exit_task() we're already
+		 * holding ctx->mutex which would be an inversion wrt. the
+		 * normal lock order.
+		 *
+		 * However we can safely take this lock because its the child
+		 * ctx->mutex.
+		 */
+		mutex_lock_nested(&owner->perf_event_mutex, SINGLE_DEPTH_NESTING);
+
+		/*
+		 * We have to re-check the event->owner field, if it is cleared
+		 * we raced with perf_event_exit_task(), acquiring the mutex
+		 * ensured they're done, and we can proceed with freeing the
+		 * event.
+		 */
+		if (event->owner) {
+			list_del_init(&event->owner_entry);
+			smp_store_release(&event->owner, NULL);
+		}
+		mutex_unlock(&owner->perf_event_mutex);
+		put_task_struct(owner);
+	}
+}
+
+static void put_event(struct perf_event *event)
+{
+	if (!atomic_long_dec_and_test(&event->refcount))
+		return;
+
+	_free_event(event);
+}
+
+/*
+ * Kill an event dead; while event:refcount will preserve the event
+ * object, it will not preserve its functionality. Once the last 'user'
+ * gives up the object, we'll destroy the thing.
+ */
+int perf_event_release_kernel(struct perf_event *event)
+{
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_event *child, *tmp;
+	LIST_HEAD(free_list);
+
+	/*
+	 * If we got here through err_file: fput(event_file); we will not have
+	 * attached to a context yet.
+	 */
+	if (!ctx) {
+		WARN_ON_ONCE(event->attach_state &
+				(PERF_ATTACH_CONTEXT|PERF_ATTACH_GROUP));
+		goto no_ctx;
+	}
+
+	if (!is_kernel_event(event))
+		perf_remove_from_owner(event);
+
+	ctx = perf_event_ctx_lock(event);
+	WARN_ON_ONCE(ctx->parent_ctx);
+
+	/*
+	 * Mark this event as STATE_DEAD, there is no external reference to it
+	 * anymore.
+	 *
+	 * Anybody acquiring event->child_mutex after the below loop _must_
+	 * also see this, most importantly inherit_event() which will avoid
+	 * placing more children on the list.
+	 *
+	 * Thus this guarantees that we will in fact observe and kill _ALL_
+	 * child events.
+	 */
+	perf_remove_from_context(event, DETACH_GROUP|DETACH_DEAD);
+
+	perf_event_ctx_unlock(event, ctx);
+
+again:
+	mutex_lock(&event->child_mutex);
+	list_for_each_entry(child, &event->child_list, child_list) {
+
+		/*
+		 * Cannot change, child events are not migrated, see the
+		 * comment with perf_event_ctx_lock_nested().
+		 */
+		ctx = READ_ONCE(child->ctx);
+		/*
+		 * Since child_mutex nests inside ctx::mutex, we must jump
+		 * through hoops. We start by grabbing a reference on the ctx.
+		 *
+		 * Since the event cannot get freed while we hold the
+		 * child_mutex, the context must also exist and have a !0
+		 * reference count.
+		 */
+		get_ctx(ctx);
+
+		/*
+		 * Now that we have a ctx ref, we can drop child_mutex, and
+		 * acquire ctx::mutex without fear of it going away. Then we
+		 * can re-acquire child_mutex.
+		 */
+		mutex_unlock(&event->child_mutex);
+		mutex_lock(&ctx->mutex);
+		mutex_lock(&event->child_mutex);
+
+		/*
+		 * Now that we hold ctx::mutex and child_mutex, revalidate our
+		 * state, if child is still the first entry, it didn't get freed
+		 * and we can continue doing so.
+		 */
+		tmp = list_first_entry_or_null(&event->child_list,
+					       struct perf_event, child_list);
+		if (tmp == child) {
+			perf_remove_from_context(child, DETACH_GROUP);
+			list_move(&child->child_list, &free_list);
+			/*
+			 * This matches the refcount bump in inherit_event();
+			 * this can't be the last reference.
+			 */
+			put_event(event);
+		}
+
+		mutex_unlock(&event->child_mutex);
+		mutex_unlock(&ctx->mutex);
+		put_ctx(ctx);
+		goto again;
+	}
+	mutex_unlock(&event->child_mutex);
+
+	list_for_each_entry_safe(child, tmp, &free_list, child_list) {
+		void *var = &child->ctx->refcount;
+
+		list_del(&child->child_list);
+		free_event(child);
+
+		/*
+		 * Wake any perf_event_free_task() waiting for this event to be
+		 * freed.
+		 */
+		smp_mb(); /* pairs with wait_var_event() */
+		wake_up_var(var);
+	}
+
+no_ctx:
+	put_event(event); /* Must be the 'last' reference */
+	return 0;
+}
+EXPORT_SYMBOL_GPL(perf_event_release_kernel);
+
+/*
+ * Called when the last reference to the file is gone.
+ */
+static int perf_release(struct inode *inode, struct file *file)
+{
+	perf_event_release_kernel(file->private_data);
+	return 0;
+}
+
+static u64 __perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
+{
+	struct perf_event *child;
+	u64 total = 0;
+
+	*enabled = 0;
+	*running = 0;
+
+	mutex_lock(&event->child_mutex);
+
+	(void)perf_event_read(event, false);
+	total += perf_event_count(event);
+
+	*enabled += event->total_time_enabled +
+			atomic64_read(&event->child_total_time_enabled);
+	*running += event->total_time_running +
+			atomic64_read(&event->child_total_time_running);
+
+	list_for_each_entry(child, &event->child_list, child_list) {
+		(void)perf_event_read(child, false);
+		total += perf_event_count(child);
+		*enabled += child->total_time_enabled;
+		*running += child->total_time_running;
+	}
+	mutex_unlock(&event->child_mutex);
+
+	return total;
+}
+
+u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
+{
+	struct perf_event_context *ctx;
+	u64 count;
+
+	ctx = perf_event_ctx_lock(event);
+	count = __perf_event_read_value(event, enabled, running);
+	perf_event_ctx_unlock(event, ctx);
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(perf_event_read_value);
+
+static int __perf_read_group_add(struct perf_event *leader,
+					u64 read_format, u64 *values)
+{
+	struct perf_event_context *ctx = leader->ctx;
+	struct perf_event *sub, *parent;
+	unsigned long flags;
+	int n = 1; /* skip @nr */
+	int ret;
+
+	ret = perf_event_read(leader, true);
+	if (ret)
+		return ret;
+
+	raw_spin_lock_irqsave(&ctx->lock, flags);
+	/*
+	 * Verify the grouping between the parent and child (inherited)
+	 * events is still in tact.
+	 *
+	 * Specifically:
+	 *  - leader->ctx->lock pins leader->sibling_list
+	 *  - parent->child_mutex pins parent->child_list
+	 *  - parent->ctx->mutex pins parent->sibling_list
+	 *
+	 * Because parent->ctx != leader->ctx (and child_list nests inside
+	 * ctx->mutex), group destruction is not atomic between children, also
+	 * see perf_event_release_kernel(). Additionally, parent can grow the
+	 * group.
+	 *
+	 * Therefore it is possible to have parent and child groups in a
+	 * different configuration and summing over such a beast makes no sense
+	 * what so ever.
+	 *
+	 * Reject this.
+	 */
+	parent = leader->parent;
+	if (parent &&
+	    (parent->group_generation != leader->group_generation ||
+	     parent->nr_siblings != leader->nr_siblings)) {
+		ret = -ECHILD;
+		goto unlock;
+	}
+
+	/*
+	 * Since we co-schedule groups, {enabled,running} times of siblings
+	 * will be identical to those of the leader, so we only publish one
+	 * set.
+	 */
+	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
+		values[n++] += leader->total_time_enabled +
+			atomic64_read(&leader->child_total_time_enabled);
+	}
+
+	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
+		values[n++] += leader->total_time_running +
+			atomic64_read(&leader->child_total_time_running);
+	}
+
+	/*
+	 * Write {count,id} tuples for every sibling.
+	 */
+	values[n++] += perf_event_count(leader);
+	if (read_format & PERF_FORMAT_ID)
+		values[n++] = primary_event_id(leader);
+	if (read_format & PERF_FORMAT_LOST)
+		values[n++] = atomic64_read(&leader->lost_samples);
+
+	for_each_sibling_event(sub, leader) {
+		values[n++] += perf_event_count(sub);
+		if (read_format & PERF_FORMAT_ID)
+			values[n++] = primary_event_id(sub);
+		if (read_format & PERF_FORMAT_LOST)
+			values[n++] = atomic64_read(&sub->lost_samples);
+	}
+
+unlock:
+	raw_spin_unlock_irqrestore(&ctx->lock, flags);
+	return ret;
+}
+
+static int perf_read_group(struct perf_event *event,
+				   u64 read_format, char __user *buf)
+{
+	struct perf_event *leader = event->group_leader, *child;
+	struct perf_event_context *ctx = leader->ctx;
+	int ret;
+	u64 *values;
+
+	lockdep_assert_held(&ctx->mutex);
+
+	values = kzalloc(event->read_size, GFP_KERNEL);
+	if (!values)
+		return -ENOMEM;
+
+	values[0] = 1 + leader->nr_siblings;
+
+	mutex_lock(&leader->child_mutex);
+
+	ret = __perf_read_group_add(leader, read_format, values);
+	if (ret)
+		goto unlock;
+
+	list_for_each_entry(child, &leader->child_list, child_list) {
+		ret = __perf_read_group_add(child, read_format, values);
+		if (ret)
+			goto unlock;
+	}
+
+	mutex_unlock(&leader->child_mutex);
+
+	ret = event->read_size;
+	if (copy_to_user(buf, values, event->read_size))
+		ret = -EFAULT;
+	goto out;
+
+unlock:
+	mutex_unlock(&leader->child_mutex);
+out:
+	kfree(values);
+	return ret;
+}
+
+static int perf_read_one(struct perf_event *event,
+				 u64 read_format, char __user *buf)
+{
+	u64 enabled, running;
+	u64 values[5];
+	int n = 0;
+
+	values[n++] = __perf_event_read_value(event, &enabled, &running);
+	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+		values[n++] = enabled;
+	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+		values[n++] = running;
+	if (read_format & PERF_FORMAT_ID)
+		values[n++] = primary_event_id(event);
+	if (read_format & PERF_FORMAT_LOST)
+		values[n++] = atomic64_read(&event->lost_samples);
+
+	if (copy_to_user(buf, values, n * sizeof(u64)))
+		return -EFAULT;
+
+	return n * sizeof(u64);
+}
+
+static bool is_event_hup(struct perf_event *event)
+{
+	bool no_children;
+
+	if (event->state > PERF_EVENT_STATE_EXIT)
+		return false;
+
+	mutex_lock(&event->child_mutex);
+	no_children = list_empty(&event->child_list);
+	mutex_unlock(&event->child_mutex);
+	return no_children;
+}
+
+/*
+ * Read the performance event - simple non blocking version for now
+ */
+static ssize_t
+__perf_read(struct perf_event *event, char __user *buf, size_t count)
+{
+	u64 read_format = event->attr.read_format;
+	int ret;
+
+	/*
+	 * Return end-of-file for a read on an event that is in
+	 * error state (i.e. because it was pinned but it couldn't be
+	 * scheduled on to the CPU at some point).
+	 */
+	if (event->state == PERF_EVENT_STATE_ERROR)
+		return 0;
+
+	if (count < event->read_size)
+		return -ENOSPC;
+
+	WARN_ON_ONCE(event->ctx->parent_ctx);
+	if (read_format & PERF_FORMAT_GROUP)
+		ret = perf_read_group(event, read_format, buf);
+	else
+		ret = perf_read_one(event, read_format, buf);
+
+	return ret;
+}
+
+static ssize_t
+perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+	struct perf_event *event = file->private_data;
+	struct perf_event_context *ctx;
+	int ret;
+
+	ret = security_perf_event_read(event);
+	if (ret)
+		return ret;
+
+	ctx = perf_event_ctx_lock(event);
+	ret = __perf_read(event, buf, count);
+	perf_event_ctx_unlock(event, ctx);
+
+	return ret;
+}
+
+static __poll_t perf_poll(struct file *file, poll_table *wait)
+{
+	struct perf_event *event = file->private_data;
+	struct perf_buffer *rb;
+	__poll_t events = EPOLLHUP;
+
+	poll_wait(file, &event->waitq, wait);
+
+	if (is_event_hup(event))
+		return events;
+
+	/*
+	 * Pin the event->rb by taking event->mmap_mutex; otherwise
+	 * perf_event_set_output() can swizzle our rb and make us miss wakeups.
+	 */
+	mutex_lock(&event->mmap_mutex);
+	rb = event->rb;
+	if (rb)
+		events = atomic_xchg(&rb->poll, 0);
+	mutex_unlock(&event->mmap_mutex);
+	return events;
+}
+
+static void _perf_event_reset(struct perf_event *event)
+{
+	(void)perf_event_read(event, false);
+	local64_set(&event->count, 0);
+	perf_event_update_userpage(event);
+}
+
+/* Assume it's not an event with inherit set. */
+u64 perf_event_pause(struct perf_event *event, bool reset)
+{
+	struct perf_event_context *ctx;
+	u64 count;
+
+	ctx = perf_event_ctx_lock(event);
+	WARN_ON_ONCE(event->attr.inherit);
+	_perf_event_disable(event);
+	count = local64_read(&event->count);
+	if (reset)
+		local64_set(&event->count, 0);
+	perf_event_ctx_unlock(event, ctx);
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(perf_event_pause);
+
+/*
+ * Holding the top-level event's child_mutex means that any
+ * descendant process that has inherited this event will block
+ * in perf_event_exit_event() if it goes to exit, thus satisfying the
+ * task existence requirements of perf_event_enable/disable.
+ */
+static void perf_event_for_each_child(struct perf_event *event,
+					void (*func)(struct perf_event *))
+{
+	struct perf_event *child;
+
+	WARN_ON_ONCE(event->ctx->parent_ctx);
+
+	mutex_lock(&event->child_mutex);
+	func(event);
+	list_for_each_entry(child, &event->child_list, child_list)
+		func(child);
+	mutex_unlock(&event->child_mutex);
+}
+
+static void perf_event_for_each(struct perf_event *event,
+				  void (*func)(struct perf_event *))
+{
+	struct perf_event_context *ctx = event->ctx;
+	struct perf_event *sibling;
+
+	lockdep_assert_held(&ctx->mutex);
+
+	event = event->group_leader;
+
+	perf_event_for_each_child(event, func);
+	for_each_sibling_event(sibling, event)
+		perf_event_for_each_child(sibling, func);
+}
+
+static void __perf_event_period(struct perf_event *event,
+				struct perf_cpu_context *cpuctx,
+				struct perf_event_context *ctx,
+				void *info)
+{
+	u64 value = *((u64 *)info);
+	bool active;
+
+	if (event->attr.freq) {
+		event->attr.sample_freq = value;
+	} else {
+		event->attr.sample_period = value;
+		event->hw.sample_period = value;
+	}
+
+	active = (event->state == PERF_EVENT_STATE_ACTIVE);
+	if (active) {
+		perf_pmu_disable(ctx->pmu);
+		/*
+		 * We could be throttled; unthrottle now to avoid the tick
+		 * trying to unthrottle while we already re-started the event.
+		 */
+		if (event->hw.interrupts == MAX_INTERRUPTS) {
+			event->hw.interrupts = 0;
+			perf_log_throttle(event, 1);
+		}
+		event->pmu->stop(event, PERF_EF_UPDATE);
+	}
+
+	local64_set(&event->hw.period_left, 0);
+
+	if (active) {
+		event->pmu->start(event, PERF_EF_RELOAD);
+		perf_pmu_enable(ctx->pmu);
+	}
+}
+
+static int perf_event_check_period(struct perf_event *event, u64 value)
+{
+	return event->pmu->check_period(event, value);
+}
+
+static int _perf_event_period(struct perf_event *event, u64 value)
+{
+	if (!is_sampling_event(event))
+		return -EINVAL;
+
+	if (!value)
+		return -EINVAL;
+
+	if (event->attr.freq && value > sysctl_perf_event_sample_rate)
+		return -EINVAL;
+
+	if (perf_event_check_period(event, value))
+		return -EINVAL;
+
+	if (!event->attr.freq && (value & (1ULL << 63)))
+		return -EINVAL;
+
+	event_function_call(event, __perf_event_period, &value);
+
+	return 0;
+}
+
+int perf_event_period(struct perf_event *event, u64 value)
+{
+	struct perf_event_context *ctx;
+	int ret;
+
+	ctx = perf_event_ctx_lock(event);
+	ret = _perf_event_period(event, value);
+	perf_event_ctx_unlock(event, ctx);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(perf_event_period);
+
+static const struct file_operations perf_fops;
+
+static inline int perf_fget_light(int fd, struct fd *p)
+{
+	struct fd f = fdget(fd);
+	if (!f.file)
+		return -EBADF;
+
+	if (f.file->f_op != &perf_fops) {
+		fdput(f);
+		return -EBADF;
+	}
+	*p = f;
+	return 0;
+}
+
+static int perf_event_set_output(struct perf_event *event,
+				 struct perf_event *output_event);
+static int perf_event_set_filter(struct perf_event *event, void __user *arg);
+static int perf_copy_attr(struct perf_event_attr __user *uattr,
+			  struct perf_event_attr *attr);
+
+static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned long arg)
+{
+	void (*func)(struct perf_event *);
+	u32 flags = arg;
+
+	switch (cmd) {
+	case PERF_EVENT_IOC_ENABLE:
+		func = _perf_event_enable;
+		break;
+	case PERF_EVENT_IOC_DISABLE:
+		func = _perf_event_disable;
+		break;
+	case PERF_EVENT_IOC_RESET:
+		func = _perf_event_reset;
+		break;
+
+	case PERF_EVENT_IOC_REFRESH:
+		return _perf_event_refresh(event, arg);
+
+	case PERF_EVENT_IOC_PERIOD:
+	{
+		u64 value;
+
+		if (copy_from_user(&value, (u64 __user *)arg, sizeof(value)))
+			return -EFAULT;
+
+		return _perf_event_period(event, value);
+	}
+	case PERF_EVENT_IOC_ID:
+	{
+		u64 id = primary_event_id(event);
+
+		if (copy_to_user((void __user *)arg, &id, sizeof(id)))
+			return -EFAULT;
+		return 0;
+	}
+
+	case PERF_EVENT_IOC_SET_OUTPUT:
+	{
+		int ret;
+		if (arg != -1) {
+			struct perf_event *output_event;
+			struct fd output;
+			ret = perf_fget_light(arg, &output);
+			if (ret)
+				return ret;
+			output_event = output.file->private_data;
+			ret = perf_event_set_output(event, output_event);
+			fdput(output);
+		} else {
+			ret = perf_event_set_output(event, NULL);
+		}
+		return ret;
+	}
+
+	case PERF_EVENT_IOC_SET_FILTER:
+		return perf_event_set_filter(event, (void __user *)arg);
+
+	case PERF_EVENT_IOC_SET_BPF:
+	{
+		struct bpf_prog *prog;
+		int err;
+
+		prog = bpf_prog_get(arg);
+		if (IS_ERR(prog))
+			return PTR_ERR(prog);
+
+		err = perf_event_set_bpf_prog(event, prog, 0);
+		if (err) {
+			bpf_prog_put(prog);
+			return err;
+		}
+
+		return 0;
+	}
+
+	case PERF_EVENT_IOC_PAUSE_OUTPUT: {
+		struct perf_buffer *rb;
+
+		rcu_read_lock();
+		rb = rcu_dereference(event->rb);
+		if (!rb || !rb->nr_pages) {
+			rcu_read_unlock();
+			return -EINVAL;
+		}
+		rb_toggle_paused(rb, !!arg);
+		rcu_read_unlock();
+		return 0;
+	}
+
+	case PERF_EVENT_IOC_QUERY_BPF:
+		return perf_event_query_prog_array(event, (void __user *)arg);
+
+	case PERF_EVENT_IOC_MODIFY_ATTRIBUTES: {
+		struct perf_event_attr new_attr;
+		int err = perf_copy_attr((struct perf_event_attr __user *)arg,
+					 &new_attr);
+
+		if (err)
+			return err;
+
+		return perf_event_modify_attr(event,  &new_attr);
+	}
+	default:
+		return -ENOTTY;
+	}
+
+	if (flags & PERF_IOC_FLAG_GROUP)
+		perf_event_for_each(event, func);
+	else
+		perf_event_for_each_child(event, func);
+
+	return 0;
+}
+
+static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct perf_event *event = file->private_data;
+	struct perf_event_context *ctx;
+	long ret;
+
+	/* Treat ioctl like writes as it is likely a mutating operation. */
+	ret = security_perf_event_write(event);
+	if (ret)
+		return ret;
+
+	ctx = perf_event_ctx_lock(event);
+	ret = _perf_ioctl(event, cmd, arg);
+	perf_event_ctx_unlock(event, ctx);
+
+	return ret;
+}
+
+#ifdef CONFIG_COMPAT
+static long perf_compat_ioctl(struct file *file, unsigned int cmd,
+				unsigned long arg)
+{
+	switch (_IOC_NR(cmd)) {
+	case _IOC_NR(PERF_EVENT_IOC_SET_FILTER):
+	case _IOC_NR(PERF_EVENT_IOC_ID):
+	case _IOC_NR(PERF_EVENT_IOC_QUERY_BPF):
+	case _IOC_NR(PERF_EVENT_IOC_MODIFY_ATTRIBUTES):
+		/* Fix up pointer size (usually 4 -> 8 in 32-on-64-bit case */
+		if (_IOC_SIZE(cmd) == sizeof(compat_uptr_t)) {
+			cmd &= ~IOCSIZE_MASK;
+			cmd |= sizeof(void *) << IOCSIZE_SHIFT;
+		}
+		break;
+	}
+	return perf_ioctl(file, cmd, arg);
+}
+#else
+# define perf_compat_ioctl NULL
+#endif
+
+int perf_event_task_enable(void)
+{
+	struct perf_event_context *ctx;
+	struct perf_event *event;
+
+	mutex_lock(&current->perf_event_mutex);
+	list_for_each_entry(event, &current->perf_event_list, owner_entry) {
+		ctx = perf_event_ctx_lock(event);
+		perf_event_for_each_child(event, _perf_event_enable);
+		perf_event_ctx_unlock(event, ctx);
+	}
+	mutex_unlock(&current->perf_event_mutex);
+
+	return 0;
+}
+
+int perf_event_task_disable(void)
+{
+	struct perf_event_context *ctx;
+	struct perf_event *event;
+
+	mutex_lock(&current->perf_event_mutex);
+	list_for_each_entry(event, &current->perf_event_list, owner_entry) {
+		ctx = perf_event_ctx_lock(event);
+		perf_event_for_each_child(event, _perf_event_disable);
+		perf_event_ctx_unlock(event, ctx);
+	}
+	mutex_unlock(&current->perf_event_mutex);
+
+	return 0;
+}
+
+static int perf_event_index(struct perf_event *event)
+{
+	if (event->hw.state & PERF_HES_STOPPED)
+		return 0;
+
+	if (event->state != PERF_EVENT_STATE_ACTIVE)
+		return 0;
+
+	return event->pmu->event_idx(event);
+}
+
+static void perf_event_init_userpage(struct perf_event *event)
+{
+	struct perf_event_mmap_page *userpg;
+	struct perf_buffer *rb;
+
+	rcu_read_lock();
+	rb = rcu_dereference(event->rb);
+	if (!rb)
+		goto unlock;
+
+	userpg = rb->user_page;
+
+	/* Allow new userspace to detect that bit 0 is deprecated */
+	userpg->cap_bit0_is_deprecated = 1;
+	userpg->size = offsetof(struct perf_event_mmap_page, __reserved);
+	userpg->data_offset = PAGE_SIZE;
+	userpg->data_size = perf_data_size(rb);
+
+unlock:
+	rcu_read_unlock();
+}
+
+void __weak arch_perf_update_userpage(
+	struct perf_event *event, struct perf_event_mmap_page *userpg, u64 now)
+{
+}
+
+/*
+ * Callers need to ensure there can be no nesting of this function, otherwise
+ * the seqlock logic goes bad. We can not serialize this because the arch
+ * code calls this from NMI context.
+ */
+void perf_event_update_userpage(struct perf_event *event)
+{
+	struct perf_event_mmap_page *userpg;
+	struct perf_buffer *rb;
+	u64 enabled, running, now;
+
+	rcu_read_lock();
+	rb = rcu_dereference(event->rb);
+	if (!rb)
+		goto unlock;
+
+	/*
+	 * compute total_time_enabled, total_time_running
+	 * based on snapshot values taken when the event
+	 * was last scheduled in.
+	 *
+	 * we cannot simply called update_context_time()
+	 * because of locking issue as we can be called in
+	 * NMI context
+	 */
+	calc_timer_values(event, &now, &enabled, &running);
+
+	userpg = rb->user_page;
+	/*
+	 * Disable preemption to guarantee consistent time stamps are stored to
+	 * the user page.
+	 */
+	preempt_disable();
+	++userpg->lock;
+	barrier();
+	userpg->index = perf_event_index(event);
+	userpg->offset = perf_event_count(event);
+	if (userpg->index)
+		userpg->offset -= local64_read(&event->hw.prev_count);
+
+	userpg->time_enabled = enabled +
+			atomic64_read(&event->child_total_time_enabled);
+
+	userpg->time_running = running +
+			atomic64_read(&event->child_total_time_running);
+
+	arch_perf_update_userpage(event, userpg, now);
+
+	barrier();
+	++userpg->lock;
+	preempt_enable();
+unlock:
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(perf_event_update_userpage);
+
+static vm_fault_t perf_mmap_fault(struct vm_fault *vmf)
+{
+	struct perf_event *event = vmf->vma->vm_file->private_data;
+	struct perf_buffer *rb;
+	vm_fault_t ret = VM_FAULT_SIGBUS;
+
+	if (vmf->flags & FAULT_FLAG_MKWRITE) {
+		if (vmf->pgoff == 0)
+			ret = 0;
+		return ret;
+	}
+
+	rcu_read_lock();
+	rb = rcu_dereference(event->rb);
+	if (!rb)
+		goto unlock;
+
+	if (vmf->pgoff && (vmf->flags & FAULT_FLAG_WRITE))
+		goto unlock;
+
+	vmf->page = perf_mmap_to_page(rb, vmf->pgoff);
+	if (!vmf->page)
+		goto unlock;
+
+	get_page(vmf->page);
+	vmf->page->mapping = vmf->vma->vm_file->f_mapping;
+	vmf->page->index   = vmf->pgoff;
+
+	ret = 0;
+unlock:
+	rcu_read_unlock();
+
+	return ret;
+}
+
+static void ring_buffer_attach(struct perf_event *event,
+			       struct perf_buffer *rb)
+{
+	struct perf_buffer *old_rb = NULL;
+	unsigned long flags;
+
+	WARN_ON_ONCE(event->parent);
+
+	if (event->rb) {
+		/*
+		 * Should be impossible, we set this when removing
+		 * event->rb_entry and wait/clear when adding event->rb_entry.
+		 */
+		WARN_ON_ONCE(event->rcu_pending);
+
+		old_rb = event->rb;
+		spin_lock_irqsave(&old_rb->event_lock, flags);
+		list_del_rcu(&event->rb_entry);
+		spin_unlock_irqrestore(&old_rb->event_lock, flags);
+
+		event->rcu_batches = get_state_synchronize_rcu();
+		event->rcu_pending = 1;
+	}
+
+	if (rb) {
+		if (event->rcu_pending) {
+			cond_synchronize_rcu(event->rcu_batches);
+			event->rcu_pending = 0;
+		}
+
+		spin_lock_irqsave(&rb->event_lock, flags);
+		list_add_rcu(&event->rb_entry, &rb->event_list);
+		spin_unlock_irqrestore(&rb->event_lock, flags);
+	}
+
+	/*
+	 * Avoid racing with perf_mmap_close(AUX): stop the event
+	 * before swizzling the event::rb pointer; if it's getting
+	 * unmapped, its aux_mmap_count will be 0 and it won't
+	 * restart. See the comment in __perf_pmu_output_stop().
+	 *
+	 * Data will inevitably be lost when set_output is done in
+	 * mid-air, but then again, whoever does it like this is
+	 * not in for the data anyway.
+	 */
+	if (has_aux(event))
+		perf_event_stop(event, 0);
+
+	rcu_assign_pointer(event->rb, rb);
+
+	if (old_rb) {
+		ring_buffer_put(old_rb);
+		/*
+		 * Since we detached before setting the new rb, so that we
+		 * could attach the new rb, we could have missed a wakeup.
+		 * Provide it now.
+		 */
+		wake_up_all(&event->waitq);
+	}
+}
+
+static void ring_buffer_wakeup(struct perf_event *event)
+{
+	struct perf_buffer *rb;
+
+	if (event->parent)
+		event = event->parent;
+
+	rcu_read_lock();
+	rb = rcu_dereference(event->rb);
+	if (rb) {
+		list_for_each_entry_rcu(event, &rb->event_list, rb_entry)
+			wake_up_all(&event->waitq);
+	}
+	rcu_read_unlock();
+}
+
+struct perf_buffer *ring_buffer_get(struct perf_event *event)
+{
+	struct perf_buffer *rb;
+
+	if (event->parent)
+		event = event->parent;
+
+	rcu_read_lock();
+	rb = rcu_dereference(event->rb);
+	if (rb) {
+		if (!refcount_inc_not_zero(&rb->refcount))
+			rb = NULL;
+	}
+	rcu_read_unlock();
+
+	return rb;
+}
+
+void ring_buffer_put(struct perf_buffer *rb)
+{
+	if (!refcount_dec_and_test(&rb->refcount))
+		return;
+
+	WARN_ON_ONCE(!list_empty(&rb->event_list));
+
+	call_rcu(&rb->rcu_head, rb_free_rcu);
+}
+
+static void perf_mmap_open(struct vm_area_struct *vma)
+{
+	struct perf_event *event = vma->vm_file->private_data;
+
+	atomic_inc(&event->mmap_count);
+	atomic_inc(&event->rb->mmap_count);
+
+	if (vma->vm_pgoff)
+		atomic_inc(&event->rb->aux_mmap_count);
+
+	if (event->pmu->event_mapped)
+		event->pmu->event_mapped(event, vma->vm_mm);
+}
+
+static void perf_pmu_output_stop(struct perf_event *event);
+
+/*
+ * A buffer can be mmap()ed multiple times; either directly through the same
+ * event, or through other events by use of perf_event_set_output().
+ *
+ * In order to undo the VM accounting done by perf_mmap() we need to destroy
+ * the buffer here, where we still have a VM context. This means we need
+ * to detach all events redirecting to us.
+ */
+static void perf_mmap_close(struct vm_area_struct *vma)
+{
+	struct perf_event *event = vma->vm_file->private_data;
+	struct perf_buffer *rb = ring_buffer_get(event);
+	struct user_struct *mmap_user = rb->mmap_user;
+	int mmap_locked = rb->mmap_locked;
+	unsigned long size = perf_data_size(rb);
+	bool detach_rest = false;
+
+	if (event->pmu->event_unmapped)
+		event->pmu->event_unmapped(event, vma->vm_mm);
+
+	/*
+	 * rb->aux_mmap_count will always drop before rb->mmap_count and
+	 * event->mmap_count, so it is ok to use event->mmap_mutex to
+	 * serialize with perf_mmap here.
+	 */
+	if (rb_has_aux(rb) && vma->vm_pgoff == rb->aux_pgoff &&
+	    atomic_dec_and_mutex_lock(&rb->aux_mmap_count, &event->mmap_mutex)) {
+		/*
+		 * Stop all AUX events that are writing to this buffer,
+		 * so that we can free its AUX pages and corresponding PMU
+		 * data. Note that after rb::aux_mmap_count dropped to zero,
+		 * they won't start any more (see perf_aux_output_begin()).
+		 */
+		perf_pmu_output_stop(event);
+
+		/* now it's safe to free the pages */
+		atomic_long_sub(rb->aux_nr_pages - rb->aux_mmap_locked, &mmap_user->locked_vm);
+		atomic64_sub(rb->aux_mmap_locked, &vma->vm_mm->pinned_vm);
+
+		/* this has to be the last one */
+		rb_free_aux(rb);
+		WARN_ON_ONCE(refcount_read(&rb->aux_refcount));
+
+		mutex_unlock(&event->mmap_mutex);
+	}
+
+	if (atomic_dec_and_test(&rb->mmap_count))
+		detach_rest = true;
+
+	if (!atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex))
+		goto out_put;
+
+	ring_buffer_attach(event, NULL);
+	mutex_unlock(&event->mmap_mutex);
+
+	/* If there's still other mmap()s of this buffer, we're done. */
+	if (!detach_rest)
+		goto out_put;
+
+	/*
+	 * No other mmap()s, detach from all other events that might redirect
+	 * into the now unreachable buffer. Somewhat complicated by the
+	 * fact that rb::event_lock otherwise nests inside mmap_mutex.
+	 */
+again:
+	rcu_read_lock();
+	list_for_each_entry_rcu(event, &rb->event_list, rb_entry) {
+		if (!atomic_long_inc_not_zero(&event->refcount)) {
+			/*
+			 * This event is en-route to free_event() which will
+			 * detach it and remove it from the list.
+			 */
+			continue;
+		}
+		rcu_read_unlock();
+
+		mutex_lock(&event->mmap_mutex);
+		/*
+		 * Check we didn't race with perf_event_set_output() which can
+		 * swizzle the rb from under us while we were waiting to
+		 * acquire mmap_mutex.
+		 *
+		 * If we find a different rb; ignore this event, a next
+		 * iteration will no longer find it on the list. We have to
+		 * still restart the iteration to make sure we're not now
+		 * iterating the wrong list.
+		 */
+		if (event->rb == rb)
+			ring_buffer_attach(event, NULL);
+
+		mutex_unlock(&event->mmap_mutex);
+		put_event(event);
+
+		/*
+		 * Restart the iteration; either we're on the wrong list or
+		 * destroyed its integrity by doing a deletion.
+		 */
+		goto again;
+	}
+	rcu_read_unlock();
+
+	/*
+	 * It could be there's still a few 0-ref events on the list; they'll
+	 * get cleaned up by free_event() -- they'll also still have their
+	 * ref on the rb and will free it whenever they are done with it.
+	 *
+	 * Aside from that, this buffer is 'fully' detached and unmapped,
+	 * undo the VM accounting.
+	 */
+
+	atomic_long_sub((size >> PAGE_SHIFT) + 1 - mmap_locked,
+			&mmap_user->locked_vm);
+	atomic64_sub(mmap_locked, &vma->vm_mm->pinned_vm);
+	free_uid(mmap_user);
+
+out_put:
+	ring_buffer_put(rb); /* could be last */
+}
+
+static const struct vm_operations_struct perf_mmap_vmops = {
+	.open		= perf_mmap_open,
+	.close		= perf_mmap_close, /* non mergeable */
+	.fault		= perf_mmap_fault,
+	.page_mkwrite	= perf_mmap_fault,
+};
+
+static int perf_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct perf_event *event = file->private_data;
+	unsigned long user_locked, user_lock_limit;
+	struct user_struct *user = current_user();
+	struct perf_buffer *rb = NULL;
+	unsigned long locked, lock_limit;
+	unsigned long vma_size;
+	unsigned long nr_pages;
+	long user_extra = 0, extra = 0;
+	int ret = 0, flags = 0;
+
+	/*
+	 * Don't allow mmap() of inherited per-task counters. This would
+	 * create a performance issue due to all children writing to the
+	 * same rb.
+	 */
+	if (event->cpu == -1 && event->attr.inherit)
+		return -EINVAL;
+
+	if (!(vma->vm_flags & VM_SHARED))
+		return -EINVAL;
+
+	ret = security_perf_event_read(event);
+	if (ret)
+		return ret;
+
+	vma_size = vma->vm_end - vma->vm_start;
+
+	if (vma->vm_pgoff == 0) {
+		nr_pages = (vma_size / PAGE_SIZE) - 1;
+	} else {
+		/*
+		 * AUX area mapping: if rb->aux_nr_pages != 0, it's already
+		 * mapped, all subsequent mappings should have the same size
+		 * and offset. Must be above the normal perf buffer.
+		 */
+		u64 aux_offset, aux_size;
+
+		if (!event->rb)
+			return -EINVAL;
+
+		nr_pages = vma_size / PAGE_SIZE;
+
+		mutex_lock(&event->mmap_mutex);
+		ret = -EINVAL;
+
+		rb = event->rb;
+		if (!rb)
+			goto aux_unlock;
+
+		aux_offset = READ_ONCE(rb->user_page->aux_offset);
+		aux_size = READ_ONCE(rb->user_page->aux_size);
+
+		if (aux_offset < perf_data_size(rb) + PAGE_SIZE)
+			goto aux_unlock;
+
+		if (aux_offset != vma->vm_pgoff << PAGE_SHIFT)
+			goto aux_unlock;
+
+		/* already mapped with a different offset */
+		if (rb_has_aux(rb) && rb->aux_pgoff != vma->vm_pgoff)
+			goto aux_unlock;
+
+		if (aux_size != vma_size || aux_size != nr_pages * PAGE_SIZE)
+			goto aux_unlock;
+
+		/* already mapped with a different size */
+		if (rb_has_aux(rb) && rb->aux_nr_pages != nr_pages)
+			goto aux_unlock;
+
+		if (!is_power_of_2(nr_pages))
+			goto aux_unlock;
+
+		if (!atomic_inc_not_zero(&rb->mmap_count))
+			goto aux_unlock;
+
+		if (rb_has_aux(rb)) {
+			atomic_inc(&rb->aux_mmap_count);
+			ret = 0;
+			goto unlock;
+		}
+
+		atomic_set(&rb->aux_mmap_count, 1);
+		user_extra = nr_pages;
+
+		goto accounting;
+	}
+
+	/*
+	 * If we have rb pages ensure they're a power-of-two number, so we
+	 * can do bitmasks instead of modulo.
+	 */
+	if (nr_pages != 0 && !is_power_of_2(nr_pages))
+		return -EINVAL;
+
+	if (vma_size != PAGE_SIZE * (1 + nr_pages))
+		return -EINVAL;
+
+	WARN_ON_ONCE(event->ctx->parent_ctx);
+again:
+	mutex_lock(&event->mmap_mutex);
+	if (event->rb) {
+		if (data_page_nr(event->rb) != nr_pages) {
+			ret = -EINVAL;
+			goto unlock;
+		}
+
+		if (!atomic_inc_not_zero(&event->rb->mmap_count)) {
+			/*
+			 * Raced against perf_mmap_close(); remove the
+			 * event and try again.
+			 */
+			ring_buffer_attach(event, NULL);
+			mutex_unlock(&event->mmap_mutex);
+			goto again;
+		}
+
+		goto unlock;
+	}
+
+	user_extra = nr_pages + 1;
+
+accounting:
+	user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10);
+
+	/*
+	 * Increase the limit linearly with more CPUs:
+	 */
+	user_lock_limit *= num_online_cpus();
+
+	user_locked = atomic_long_read(&user->locked_vm);
+
+	/*
+	 * sysctl_perf_event_mlock may have changed, so that
+	 *     user->locked_vm > user_lock_limit
+	 */
+	if (user_locked > user_lock_limit)
+		user_locked = user_lock_limit;
+	user_locked += user_extra;
+
+	if (user_locked > user_lock_limit) {
+		/*
+		 * charge locked_vm until it hits user_lock_limit;
+		 * charge the rest from pinned_vm
+		 */
+		extra = user_locked - user_lock_limit;
+		user_extra -= extra;
+	}
+
+	lock_limit = rlimit(RLIMIT_MEMLOCK);
+	lock_limit >>= PAGE_SHIFT;
+	locked = atomic64_read(&vma->vm_mm->pinned_vm) + extra;
+
+	if ((locked > lock_limit) && perf_is_paranoid() &&
+		!capable(CAP_IPC_LOCK)) {
+		ret = -EPERM;
+		goto unlock;
+	}
+
+	WARN_ON(!rb && event->rb);
+
+	if (vma->vm_flags & VM_WRITE)
+		flags |= RING_BUFFER_WRITABLE;
+
+	if (!rb) {
+		rb = rb_alloc(nr_pages,
+			      event->attr.watermark ? event->attr.wakeup_watermark : 0,
+			      event->cpu, flags);
+
+		if (!rb) {
+			ret = -ENOMEM;
+			goto unlock;
+		}
+
+		atomic_set(&rb->mmap_count, 1);
+		rb->mmap_user = get_current_user();
+		rb->mmap_locked = extra;
+
+		ring_buffer_attach(event, rb);
+
+		perf_event_update_time(event);
+		perf_event_init_userpage(event);
+		perf_event_update_userpage(event);
+	} else {
+		ret = rb_alloc_aux(rb, event, vma->vm_pgoff, nr_pages,
+				   event->attr.aux_watermark, flags);
+		if (!ret)
+			rb->aux_mmap_locked = extra;
+	}
+
+unlock:
+	if (!ret) {
+		atomic_long_add(user_extra, &user->locked_vm);
+		atomic64_add(extra, &vma->vm_mm->pinned_vm);
+
+		atomic_inc(&event->mmap_count);
+	} else if (rb) {
+		atomic_dec(&rb->mmap_count);
+	}
+aux_unlock:
+	mutex_unlock(&event->mmap_mutex);
+
+	/*
+	 * Since pinned accounting is per vm we cannot allow fork() to copy our
+	 * vma.
+	 */
+	vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND | VM_DONTDUMP;
+	vma->vm_ops = &perf_mmap_vmops;
+
+	if (event->pmu->event_mapped)
+		event->pmu->event_mapped(event, vma->vm_mm);
+
+	return ret;
+}
+
+static int perf_fasync(int fd, struct file *filp, int on)
+{
+	struct inode *inode = file_inode(filp);
+	struct perf_event *event = filp->private_data;
+	int retval;
+
+	inode_lock(inode);
+	retval = fasync_helper(fd, filp, on, &event->fasync);
+	inode_unlock(inode);
+
+	if (retval < 0)
+		return retval;
+
+	return 0;
+}
+
+static const struct file_operations perf_fops = {
+	.llseek			= no_llseek,
+	.release		= perf_release,
+	.read			= perf_read,
+	.poll			= perf_poll,
+	.unlocked_ioctl		= perf_ioctl,
+	.compat_ioctl		= perf_compat_ioctl,
+	.mmap			= perf_mmap,
+	.fasync			= perf_fasync,
+};
+
+/*
+ * Perf event wakeup
+ *
+ * If there's data, ensure we set the poll() state and publish everything
+ * to user-space before waking everybody up.
+ */
+
+static inline struct fasync_struct **perf_event_fasync(struct perf_event *event)
+{
+	/* only the parent has fasync state */
+	if (event->parent)
+		event = event->parent;
+	return &event->fasync;
+}
+
+void perf_event_wakeup(struct perf_event *event)
+{
+	ring_buffer_wakeup(event);
+
+	if (event->pending_kill) {
+		kill_fasync(perf_event_fasync(event), SIGIO, event->pending_kill);
+		event->pending_kill = 0;
+	}
+}
+
+static void perf_sigtrap(struct perf_event *event)
+{
+	/*
+	 * We'd expect this to only occur if the irq_work is delayed and either
+	 * ctx->task or current has changed in the meantime. This can be the
+	 * case on architectures that do not implement arch_irq_work_raise().
+	 */
+	if (WARN_ON_ONCE(event->ctx->task != current))
+		return;
+
+	/*
+	 * Both perf_pending_task() and perf_pending_irq() can race with the
+	 * task exiting.
+	 */
+	if (current->flags & PF_EXITING)
+		return;
+
+	send_sig_perf((void __user *)event->pending_addr,
+		      event->attr.type, event->attr.sig_data);
+}
+
+/*
+ * Deliver the pending work in-event-context or follow the context.
+ */
+static void __perf_pending_irq(struct perf_event *event)
+{
+	int cpu = READ_ONCE(event->oncpu);
+
+	/*
+	 * If the event isn't running; we done. event_sched_out() will have
+	 * taken care of things.
+	 */
+	if (cpu < 0)
+		return;
+
+	/*
+	 * Yay, we hit home and are in the context of the event.
+	 */
+	if (cpu == smp_processor_id()) {
+		if (event->pending_sigtrap) {
+			event->pending_sigtrap = 0;
+			perf_sigtrap(event);
+			local_dec(&event->ctx->nr_pending);
+		}
+		if (event->pending_disable) {
+			event->pending_disable = 0;
+			perf_event_disable_local(event);
+		}
+		return;
+	}
+
+	/*
+	 *  CPU-A			CPU-B
+	 *
+	 *  perf_event_disable_inatomic()
+	 *    @pending_disable = CPU-A;
+	 *    irq_work_queue();
+	 *
+	 *  sched-out
+	 *    @pending_disable = -1;
+	 *
+	 *				sched-in
+	 *				perf_event_disable_inatomic()
+	 *				  @pending_disable = CPU-B;
+	 *				  irq_work_queue(); // FAILS
+	 *
+	 *  irq_work_run()
+	 *    perf_pending_irq()
+	 *
+	 * But the event runs on CPU-B and wants disabling there.
+	 */
+	irq_work_queue_on(&event->pending_irq, cpu);
+}
+
+static void perf_pending_irq(struct irq_work *entry)
+{
+	struct perf_event *event = container_of(entry, struct perf_event, pending_irq);
+	int rctx;
+
+	/*
+	 * If we 'fail' here, that's OK, it means recursion is already disabled
+	 * and we won't recurse 'further'.
+	 */
+	rctx = perf_swevent_get_recursion_context();
+
+	/*
+	 * The wakeup isn't bound to the context of the event -- it can happen
+	 * irrespective of where the event is.
+	 */
+	if (event->pending_wakeup) {
+		event->pending_wakeup = 0;
+		perf_event_wakeup(event);
+	}
+
+	__perf_pending_irq(event);
+
+	if (rctx >= 0)
+		perf_swevent_put_recursion_context(rctx);
+}
+
+static void perf_pending_task(struct callback_head *head)
+{
+	struct perf_event *event = container_of(head, struct perf_event, pending_task);
+	int rctx;
+
+	/*
+	 * If we 'fail' here, that's OK, it means recursion is already disabled
+	 * and we won't recurse 'further'.
+	 */
+	preempt_disable_notrace();
+	rctx = perf_swevent_get_recursion_context();
+
+	if (event->pending_work) {
+		event->pending_work = 0;
+		perf_sigtrap(event);
+		local_dec(&event->ctx->nr_pending);
+	}
+
+	if (rctx >= 0)
+		perf_swevent_put_recursion_context(rctx);
+	preempt_enable_notrace();
+
+	put_event(event);
+}
+
+#ifdef CONFIG_GUEST_PERF_EVENTS
+struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
+
+DEFINE_STATIC_CALL_RET0(__perf_guest_state, *perf_guest_cbs->state);
+DEFINE_STATIC_CALL_RET0(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
+DEFINE_STATIC_CALL_RET0(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
+
+void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs)))
+		return;
+
+	rcu_assign_pointer(perf_guest_cbs, cbs);
+	static_call_update(__perf_guest_state, cbs->state);
+	static_call_update(__perf_guest_get_ip, cbs->get_ip);
+
+	/* Implementing ->handle_intel_pt_intr is optional. */
+	if (cbs->handle_intel_pt_intr)
+		static_call_update(__perf_guest_handle_intel_pt_intr,
+				   cbs->handle_intel_pt_intr);
+}
+EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
+
+void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs) != cbs))
+		return;
+
+	rcu_assign_pointer(perf_guest_cbs, NULL);
+	static_call_update(__perf_guest_state, (void *)&__static_call_return0);
+	static_call_update(__perf_guest_get_ip, (void *)&__static_call_return0);
+	static_call_update(__perf_guest_handle_intel_pt_intr,
+			   (void *)&__static_call_return0);
+	synchronize_rcu();
+}
+EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
+#endif
+
+static void
+perf_output_sample_regs(struct perf_output_handle *handle,
+			struct pt_regs *regs, u64 mask)
+{
+	int bit;
+	DECLARE_BITMAP(_mask, 64);
+
+	bitmap_from_u64(_mask, mask);
+	for_each_set_bit(bit, _mask, sizeof(mask) * BITS_PER_BYTE) {
+		u64 val;
+
+		val = perf_reg_value(regs, bit);
+		perf_output_put(handle, val);
+	}
+}
+
+static void perf_sample_regs_user(struct perf_regs *regs_user,
+				  struct pt_regs *regs)
+{
+	if (user_mode(regs)) {
+		regs_user->abi = perf_reg_abi(current);
+		regs_user->regs = regs;
+	} else if (!(current->flags & PF_KTHREAD)) {
+		perf_get_regs_user(regs_user, regs);
+	} else {
+		regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
+		regs_user->regs = NULL;
+	}
+}
+
+static void perf_sample_regs_intr(struct perf_regs *regs_intr,
+				  struct pt_regs *regs)
+{
+	regs_intr->regs = regs;
+	regs_intr->abi  = perf_reg_abi(current);
+}
+
+
+/*
+ * Get remaining task size from user stack pointer.
+ *
+ * It'd be better to take stack vma map and limit this more
+ * precisely, but there's no way to get it safely under interrupt,
+ * so using TASK_SIZE as limit.
+ */
+static u64 perf_ustack_task_size(struct pt_regs *regs)
+{
+	unsigned long addr = perf_user_stack_pointer(regs);
+
+	if (!addr || addr >= TASK_SIZE)
+		return 0;
+
+	return TASK_SIZE - addr;
+}
+
+static u16
+perf_sample_ustack_size(u16 stack_size, u16 header_size,
+			struct pt_regs *regs)
+{
+	u64 task_size;
+
+	/* No regs, no stack pointer, no dump. */
+	if (!regs)
+		return 0;
+
+	/*
+	 * Check if we fit in with the requested stack size into the:
+	 * - TASK_SIZE
+	 *   If we don't, we limit the size to the TASK_SIZE.
+	 *
+	 * - remaining sample size
+	 *   If we don't, we customize the stack size to
+	 *   fit in to the remaining sample size.
+	 */
+
+	task_size  = min((u64) USHRT_MAX, perf_ustack_task_size(regs));
+	stack_size = min(stack_size, (u16) task_size);
+
+	/* Current header size plus static size and dynamic size. */
+	header_size += 2 * sizeof(u64);
+
+	/* Do we fit in with the current stack dump size? */
+	if ((u16) (header_size + stack_size) < header_size) {
+		/*
+		 * If we overflow the maximum size for the sample,
+		 * we customize the stack dump size to fit in.
+		 */
+		stack_size = USHRT_MAX - header_size - sizeof(u64);
+		stack_size = round_up(stack_size, sizeof(u64));
+	}
+
+	return stack_size;
+}
+
+static void
+perf_output_sample_ustack(struct perf_output_handle *handle, u64 dump_size,
+			  struct pt_regs *regs)
+{
+	/* Case of a kernel thread, nothing to dump */
+	if (!regs) {
+		u64 size = 0;
+		perf_output_put(handle, size);
+	} else {
+		unsigned long sp;
+		unsigned int rem;
+		u64 dyn_size;
+
+		/*
+		 * We dump:
+		 * static size
+		 *   - the size requested by user or the best one we can fit
+		 *     in to the sample max size
+		 * data
+		 *   - user stack dump data
+		 * dynamic size
+		 *   - the actual dumped size
+		 */
+
+		/* Static size. */
+		perf_output_put(handle, dump_size);
+
+		/* Data. */
+		sp = perf_user_stack_pointer(regs);
+		rem = __output_copy_user(handle, (void *) sp, dump_size);
+		dyn_size = dump_size - rem;
+
+		perf_output_skip(handle, rem);
+
+		/* Dynamic size. */
+		perf_output_put(handle, dyn_size);
+	}
+}
+
+static unsigned long perf_prepare_sample_aux(struct perf_event *event,
+					  struct perf_sample_data *data,
+					  size_t size)
+{
+	struct perf_event *sampler = event->aux_event;
+	struct perf_buffer *rb;
+
+	data->aux_size = 0;
+
+	if (!sampler)
+		goto out;
+
+	if (WARN_ON_ONCE(READ_ONCE(sampler->state) != PERF_EVENT_STATE_ACTIVE))
+		goto out;
+
+	if (WARN_ON_ONCE(READ_ONCE(sampler->oncpu) != smp_processor_id()))
+		goto out;
+
+	rb = ring_buffer_get(sampler);
+	if (!rb)
+		goto out;
+
+	/*
+	 * If this is an NMI hit inside sampling code, don't take
+	 * the sample. See also perf_aux_sample_output().
+	 */
+	if (READ_ONCE(rb->aux_in_sampling)) {
+		data->aux_size = 0;
+	} else {
+		size = min_t(size_t, size, perf_aux_size(rb));
+		data->aux_size = ALIGN(size, sizeof(u64));
+	}
+	ring_buffer_put(rb);
+
+out:
+	return data->aux_size;
+}
+
+static long perf_pmu_snapshot_aux(struct perf_buffer *rb,
+                                 struct perf_event *event,
+                                 struct perf_output_handle *handle,
+                                 unsigned long size)
+{
+	unsigned long flags;
+	long ret;
+
+	/*
+	 * Normal ->start()/->stop() callbacks run in IRQ mode in scheduler
+	 * paths. If we start calling them in NMI context, they may race with
+	 * the IRQ ones, that is, for example, re-starting an event that's just
+	 * been stopped, which is why we're using a separate callback that
+	 * doesn't change the event state.
+	 *
+	 * IRQs need to be disabled to prevent IPIs from racing with us.
+	 */
+	local_irq_save(flags);
+	/*
+	 * Guard against NMI hits inside the critical section;
+	 * see also perf_prepare_sample_aux().
+	 */
+	WRITE_ONCE(rb->aux_in_sampling, 1);
+	barrier();
+
+	ret = event->pmu->snapshot_aux(event, handle, size);
+
+	barrier();
+	WRITE_ONCE(rb->aux_in_sampling, 0);
+	local_irq_restore(flags);
+
+	return ret;
+}
+
+static void perf_aux_sample_output(struct perf_event *event,
+				   struct perf_output_handle *handle,
+				   struct perf_sample_data *data)
+{
+	struct perf_event *sampler = event->aux_event;
+	struct perf_buffer *rb;
+	unsigned long pad;
+	long size;
+
+	if (WARN_ON_ONCE(!sampler || !data->aux_size))
+		return;
+
+	rb = ring_buffer_get(sampler);
+	if (!rb)
+		return;
+
+	size = perf_pmu_snapshot_aux(rb, sampler, handle, data->aux_size);
+
+	/*
+	 * An error here means that perf_output_copy() failed (returned a
+	 * non-zero surplus that it didn't copy), which in its current
+	 * enlightened implementation is not possible. If that changes, we'd
+	 * like to know.
+	 */
+	if (WARN_ON_ONCE(size < 0))
+		goto out_put;
+
+	/*
+	 * The pad comes from ALIGN()ing data->aux_size up to u64 in
+	 * perf_prepare_sample_aux(), so should not be more than that.
+	 */
+	pad = data->aux_size - size;
+	if (WARN_ON_ONCE(pad >= sizeof(u64)))
+		pad = 8;
+
+	if (pad) {
+		u64 zero = 0;
+		perf_output_copy(handle, &zero, pad);
+	}
+
+out_put:
+	ring_buffer_put(rb);
+}
+
+static void __perf_event_header__init_id(struct perf_event_header *header,
+					 struct perf_sample_data *data,
+					 struct perf_event *event,
+					 u64 sample_type)
+{
+	data->type = event->attr.sample_type;
+	header->size += event->id_header_size;
+
+	if (sample_type & PERF_SAMPLE_TID) {
+		/* namespace issues */
+		data->tid_entry.pid = perf_event_pid(event, current);
+		data->tid_entry.tid = perf_event_tid(event, current);
+	}
+
+	if (sample_type & PERF_SAMPLE_TIME)
+		data->time = perf_event_clock(event);
+
+	if (sample_type & (PERF_SAMPLE_ID | PERF_SAMPLE_IDENTIFIER))
+		data->id = primary_event_id(event);
+
+	if (sample_type & PERF_SAMPLE_STREAM_ID)
+		data->stream_id = event->id;
+
+	if (sample_type & PERF_SAMPLE_CPU) {
+		data->cpu_entry.cpu	 = raw_smp_processor_id();
+		data->cpu_entry.reserved = 0;
+	}
+}
+
+void perf_event_header__init_id(struct perf_event_header *header,
+				struct perf_sample_data *data,
+				struct perf_event *event)
+{
+	if (event->attr.sample_id_all)
+		__perf_event_header__init_id(header, data, event, event->attr.sample_type);
+}
+
+static void __perf_event__output_id_sample(struct perf_output_handle *handle,
+					   struct perf_sample_data *data)
+{
+	u64 sample_type = data->type;
+
+	if (sample_type & PERF_SAMPLE_TID)
+		perf_output_put(handle, data->tid_entry);
+
+	if (sample_type & PERF_SAMPLE_TIME)
+		perf_output_put(handle, data->time);
+
+	if (sample_type & PERF_SAMPLE_ID)
+		perf_output_put(handle, data->id);
+
+	if (sample_type & PERF_SAMPLE_STREAM_ID)
+		perf_output_put(handle, data->stream_id);
+
+	if (sample_type & PERF_SAMPLE_CPU)
+		perf_output_put(handle, data->cpu_entry);
+
+	if (sample_type & PERF_SAMPLE_IDENTIFIER)
+		perf_output_put(handle, data->id);
+}
+
+void perf_event__output_id_sample(struct perf_event *event,
+				  struct perf_output_handle *handle,
+				  struct perf_sample_data *sample)
+{
+	if (event->attr.sample_id_all)
+		__perf_event__output_id_sample(handle, sample);
+}
+
+static void perf_output_read_one(struct perf_output_handle *handle,
+				 struct perf_event *event,
+				 u64 enabled, u64 running)
+{
+	u64 read_format = event->attr.read_format;
+	u64 values[5];
+	int n = 0;
+
+	values[n++] = perf_event_count(event);
+	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
+		values[n++] = enabled +
+			atomic64_read(&event->child_total_time_enabled);
+	}
+	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
+		values[n++] = running +
+			atomic64_read(&event->child_total_time_running);
+	}
+	if (read_format & PERF_FORMAT_ID)
+		values[n++] = primary_event_id(event);
+	if (read_format & PERF_FORMAT_LOST)
+		values[n++] = atomic64_read(&event->lost_samples);
+
+	__output_copy(handle, values, n * sizeof(u64));
+}
+
+static void perf_output_read_group(struct perf_output_handle *handle,
+			    struct perf_event *event,
+			    u64 enabled, u64 running)
+{
+	struct perf_event *leader = event->group_leader, *sub;
+	u64 read_format = event->attr.read_format;
+	unsigned long flags;
+	u64 values[6];
+	int n = 0;
+
+	/*
+	 * Disabling interrupts avoids all counter scheduling
+	 * (context switches, timer based rotation and IPIs).
+	 */
+	local_irq_save(flags);
+
+	values[n++] = 1 + leader->nr_siblings;
+
+	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+		values[n++] = enabled;
+
+	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+		values[n++] = running;
+
+	if ((leader != event) &&
+	    (leader->state == PERF_EVENT_STATE_ACTIVE))
+		leader->pmu->read(leader);
+
+	values[n++] = perf_event_count(leader);
+	if (read_format & PERF_FORMAT_ID)
+		values[n++] = primary_event_id(leader);
+	if (read_format & PERF_FORMAT_LOST)
+		values[n++] = atomic64_read(&leader->lost_samples);
+
+	__output_copy(handle, values, n * sizeof(u64));
+
+	for_each_sibling_event(sub, leader) {
+		n = 0;
+
+		if ((sub != event) &&
+		    (sub->state == PERF_EVENT_STATE_ACTIVE))
+			sub->pmu->read(sub);
+
+		values[n++] = perf_event_count(sub);
+		if (read_format & PERF_FORMAT_ID)
+			values[n++] = primary_event_id(sub);
+		if (read_format & PERF_FORMAT_LOST)
+			values[n++] = atomic64_read(&sub->lost_samples);
+
+		__output_copy(handle, values, n * sizeof(u64));
+	}
+
+	local_irq_restore(flags);
+}
+
+#define PERF_FORMAT_TOTAL_TIMES (PERF_FORMAT_TOTAL_TIME_ENABLED|\
+				 PERF_FORMAT_TOTAL_TIME_RUNNING)
+
+/*
+ * XXX PERF_SAMPLE_READ vs inherited events seems difficult.
+ *
+ * The problem is that its both hard and excessively expensive to iterate the
+ * child list, not to mention that its impossible to IPI the children running
+ * on another CPU, from interrupt/NMI context.
+ */
+static void perf_output_read(struct perf_output_handle *handle,
+			     struct perf_event *event)
+{
+	u64 enabled = 0, running = 0, now;
+	u64 read_format = event->attr.read_format;
+
+	/*
+	 * compute total_time_enabled, total_time_running
+	 * based on snapshot values taken when the event
+	 * was last scheduled in.
+	 *
+	 * we cannot simply called update_context_time()
+	 * because of locking issue as we are called in
+	 * NMI context
+	 */
+	if (read_format & PERF_FORMAT_TOTAL_TIMES)
+		calc_timer_values(event, &now, &enabled, &running);
+
+	if (event->attr.read_format & PERF_FORMAT_GROUP)
+		perf_output_read_group(handle, event, enabled, running);
+	else
+		perf_output_read_one(handle, event, enabled, running);
+}
+
+void perf_output_sample(struct perf_output_handle *handle,
+			struct perf_event_header *header,
+			struct perf_sample_data *data,
+			struct perf_event *event)
+{
+	u64 sample_type = data->type;
+
+	perf_output_put(handle, *header);
+
+	if (sample_type & PERF_SAMPLE_IDENTIFIER)
+		perf_output_put(handle, data->id);
+
+	if (sample_type & PERF_SAMPLE_IP)
+		perf_output_put(handle, data->ip);
+
+	if (sample_type & PERF_SAMPLE_TID)
+		perf_output_put(handle, data->tid_entry);
+
+	if (sample_type & PERF_SAMPLE_TIME)
+		perf_output_put(handle, data->time);
+
+	if (sample_type & PERF_SAMPLE_ADDR)
+		perf_output_put(handle, data->addr);
+
+	if (sample_type & PERF_SAMPLE_ID)
+		perf_output_put(handle, data->id);
+
+	if (sample_type & PERF_SAMPLE_STREAM_ID)
+		perf_output_put(handle, data->stream_id);
+
+	if (sample_type & PERF_SAMPLE_CPU)
+		perf_output_put(handle, data->cpu_entry);
+
+	if (sample_type & PERF_SAMPLE_PERIOD)
+		perf_output_put(handle, data->period);
+
+	if (sample_type & PERF_SAMPLE_READ)
+		perf_output_read(handle, event);
+
+	if (sample_type & PERF_SAMPLE_CALLCHAIN) {
+		int size = 1;
+
+		size += data->callchain->nr;
+		size *= sizeof(u64);
+		__output_copy(handle, data->callchain, size);
+	}
+
+	if (sample_type & PERF_SAMPLE_RAW) {
+		struct perf_raw_record *raw = data->raw;
+
+		if (raw) {
+			struct perf_raw_frag *frag = &raw->frag;
+
+			perf_output_put(handle, raw->size);
+			do {
+				if (frag->copy) {
+					__output_custom(handle, frag->copy,
+							frag->data, frag->size);
+				} else {
+					__output_copy(handle, frag->data,
+						      frag->size);
+				}
+				if (perf_raw_frag_last(frag))
+					break;
+				frag = frag->next;
+			} while (1);
+			if (frag->pad)
+				__output_skip(handle, NULL, frag->pad);
+		} else {
+			struct {
+				u32	size;
+				u32	data;
+			} raw = {
+				.size = sizeof(u32),
+				.data = 0,
+			};
+			perf_output_put(handle, raw);
+		}
+	}
+
+	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+		if (data->sample_flags & PERF_SAMPLE_BRANCH_STACK) {
+			size_t size;
+
+			size = data->br_stack->nr
+			     * sizeof(struct perf_branch_entry);
+
+			perf_output_put(handle, data->br_stack->nr);
+			if (branch_sample_hw_index(event))
+				perf_output_put(handle, data->br_stack->hw_idx);
+			perf_output_copy(handle, data->br_stack->entries, size);
+		} else {
+			/*
+			 * we always store at least the value of nr
+			 */
+			u64 nr = 0;
+			perf_output_put(handle, nr);
+		}
+	}
+
+	if (sample_type & PERF_SAMPLE_REGS_USER) {
+		u64 abi = data->regs_user.abi;
+
+		/*
+		 * If there are no regs to dump, notice it through
+		 * first u64 being zero (PERF_SAMPLE_REGS_ABI_NONE).
+		 */
+		perf_output_put(handle, abi);
+
+		if (abi) {
+			u64 mask = event->attr.sample_regs_user;
+			perf_output_sample_regs(handle,
+						data->regs_user.regs,
+						mask);
+		}
+	}
+
+	if (sample_type & PERF_SAMPLE_STACK_USER) {
+		perf_output_sample_ustack(handle,
+					  data->stack_user_size,
+					  data->regs_user.regs);
+	}
+
+	if (sample_type & PERF_SAMPLE_WEIGHT_TYPE)
+		perf_output_put(handle, data->weight.full);
+
+	if (sample_type & PERF_SAMPLE_DATA_SRC)
+		perf_output_put(handle, data->data_src.val);
+
+	if (sample_type & PERF_SAMPLE_TRANSACTION)
+		perf_output_put(handle, data->txn);
+
+	if (sample_type & PERF_SAMPLE_REGS_INTR) {
+		u64 abi = data->regs_intr.abi;
+		/*
+		 * If there are no regs to dump, notice it through
+		 * first u64 being zero (PERF_SAMPLE_REGS_ABI_NONE).
+		 */
+		perf_output_put(handle, abi);
+
+		if (abi) {
+			u64 mask = event->attr.sample_regs_intr;
+
+			perf_output_sample_regs(handle,
+						data->regs_intr.regs,
+						mask);
+		}
+	}
+
+	if (sample_type & PERF_SAMPLE_PHYS_ADDR)
+		perf_output_put(handle, data->phys_addr);
+
+	if (sample_type & PERF_SAMPLE_CGROUP)
+		perf_output_put(handle, data->cgroup);
+
+	if (sample_type & PERF_SAMPLE_DATA_PAGE_SIZE)
+		perf_output_put(handle, data->data_page_size);
+
+	if (sample_type & PERF_SAMPLE_CODE_PAGE_SIZE)
+		perf_output_put(handle, data->code_page_size);
+
+	if (sample_type & PERF_SAMPLE_AUX) {
+		perf_output_put(handle, data->aux_size);
+
+		if (data->aux_size)
+			perf_aux_sample_output(event, handle, data);
+	}
+
+	if (!event->attr.watermark) {
+		int wakeup_events = event->attr.wakeup_events;
+
+		if (wakeup_events) {
+			struct perf_buffer *rb = handle->rb;
+			int events = local_inc_return(&rb->events);
+
+			if (events >= wakeup_events) {
+				local_sub(wakeup_events, &rb->events);
+				local_inc(&rb->wakeup);
+			}
+		}
+	}
+}
+
+static u64 perf_virt_to_phys(u64 virt)
+{
+	u64 phys_addr = 0;
+
+	if (!virt)
+		return 0;
+
+	if (virt >= TASK_SIZE) {
+		/* If it's vmalloc()d memory, leave phys_addr as 0 */
+		if (virt_addr_valid((void *)(uintptr_t)virt) &&
+		    !(virt >= VMALLOC_START && virt < VMALLOC_END))
+			phys_addr = (u64)virt_to_phys((void *)(uintptr_t)virt);
+	} else {
+		/*
+		 * Walking the pages tables for user address.
+		 * Interrupts are disabled, so it prevents any tear down
+		 * of the page tables.
+		 * Try IRQ-safe get_user_page_fast_only first.
+		 * If failed, leave phys_addr as 0.
+		 */
+		if (current->mm != NULL) {
+			struct page *p;
+
+			pagefault_disable();
+			if (get_user_page_fast_only(virt, 0, &p)) {
+				phys_addr = page_to_phys(p) + virt % PAGE_SIZE;
+				put_page(p);
+			}
+			pagefault_enable();
+		}
+	}
+
+	return phys_addr;
+}
+
+/*
+ * Return the pagetable size of a given virtual address.
+ */
+static u64 perf_get_pgtable_size(struct mm_struct *mm, unsigned long addr)
+{
+	u64 size = 0;
+
+#ifdef CONFIG_HAVE_FAST_GUP
+	pgd_t *pgdp, pgd;
+	p4d_t *p4dp, p4d;
+	pud_t *pudp, pud;
+	pmd_t *pmdp, pmd;
+	pte_t *ptep, pte;
+
+	pgdp = pgd_offset(mm, addr);
+	pgd = READ_ONCE(*pgdp);
+	if (pgd_none(pgd))
+		return 0;
+
+	if (pgd_leaf(pgd))
+		return pgd_leaf_size(pgd);
+
+	p4dp = p4d_offset_lockless(pgdp, pgd, addr);
+	p4d = READ_ONCE(*p4dp);
+	if (!p4d_present(p4d))
+		return 0;
+
+	if (p4d_leaf(p4d))
+		return p4d_leaf_size(p4d);
+
+	pudp = pud_offset_lockless(p4dp, p4d, addr);
+	pud = READ_ONCE(*pudp);
+	if (!pud_present(pud))
+		return 0;
+
+	if (pud_leaf(pud))
+		return pud_leaf_size(pud);
+
+	pmdp = pmd_offset_lockless(pudp, pud, addr);
+	pmd = READ_ONCE(*pmdp);
+	if (!pmd_present(pmd))
+		return 0;
+
+	if (pmd_leaf(pmd))
+		return pmd_leaf_size(pmd);
+
+	ptep = pte_offset_map(&pmd, addr);
+	pte = ptep_get_lockless(ptep);
+	if (pte_present(pte))
+		size = pte_leaf_size(pte);
+	pte_unmap(ptep);
+#endif /* CONFIG_HAVE_FAST_GUP */
+
+	return size;
+}
+
+static u64 perf_get_page_size(unsigned long addr)
+{
+	struct mm_struct *mm;
+	unsigned long flags;
+	u64 size;
+
+	if (!addr)
+		return 0;
+
+	/*
+	 * Software page-table walkers must disable IRQs,
+	 * which prevents any tear down of the page tables.
+	 */
+	local_irq_save(flags);
+
+	mm = current->mm;
+	if (!mm) {
+		/*
+		 * For kernel threads and the like, use init_mm so that
+		 * we can find kernel memory.
+		 */
+		mm = &init_mm;
+	}
+
+	size = perf_get_pgtable_size(mm, addr);
+
+	local_irq_restore(flags);
+
+	return size;
+}
+
+static struct perf_callchain_entry __empty_callchain = { .nr = 0, };
+
+struct perf_callchain_entry *
+perf_callchain(struct perf_event *event, struct pt_regs *regs)
+{
+	bool kernel = !event->attr.exclude_callchain_kernel;
+	bool user   = !event->attr.exclude_callchain_user;
+	/* Disallow cross-task user callchains. */
+	bool crosstask = event->ctx->task && event->ctx->task != current;
+	const u32 max_stack = event->attr.sample_max_stack;
+	struct perf_callchain_entry *callchain;
+
+	if (!kernel && !user)
+		return &__empty_callchain;
+
+	callchain = get_perf_callchain(regs, 0, kernel, user,
+				       max_stack, crosstask, true);
+	return callchain ?: &__empty_callchain;
+}
+
+void perf_prepare_sample(struct perf_event_header *header,
+			 struct perf_sample_data *data,
+			 struct perf_event *event,
+			 struct pt_regs *regs)
+{
+	u64 sample_type = event->attr.sample_type;
+	u64 filtered_sample_type;
+
+	header->type = PERF_RECORD_SAMPLE;
+	header->size = sizeof(*header) + event->header_size;
+
+	header->misc = 0;
+	header->misc |= perf_misc_flags(regs);
+
+	/*
+	 * Clear the sample flags that have already been done by the
+	 * PMU driver.
+	 */
+	filtered_sample_type = sample_type & ~data->sample_flags;
+	__perf_event_header__init_id(header, data, event, filtered_sample_type);
+
+	if (sample_type & (PERF_SAMPLE_IP | PERF_SAMPLE_CODE_PAGE_SIZE))
+		data->ip = perf_instruction_pointer(regs);
+
+	if (sample_type & PERF_SAMPLE_CALLCHAIN) {
+		int size = 1;
+
+		if (filtered_sample_type & PERF_SAMPLE_CALLCHAIN)
+			data->callchain = perf_callchain(event, regs);
+
+		size += data->callchain->nr;
+
+		header->size += size * sizeof(u64);
+	}
+
+	if (sample_type & PERF_SAMPLE_RAW) {
+		struct perf_raw_record *raw = data->raw;
+		int size;
+
+		if (raw && (data->sample_flags & PERF_SAMPLE_RAW)) {
+			struct perf_raw_frag *frag = &raw->frag;
+			u32 sum = 0;
+
+			do {
+				sum += frag->size;
+				if (perf_raw_frag_last(frag))
+					break;
+				frag = frag->next;
+			} while (1);
+
+			size = round_up(sum + sizeof(u32), sizeof(u64));
+			raw->size = size - sizeof(u32);
+			frag->pad = raw->size - sum;
+		} else {
+			size = sizeof(u64);
+			data->raw = NULL;
+		}
+
+		header->size += size;
+	}
+
+	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+		int size = sizeof(u64); /* nr */
+		if (data->sample_flags & PERF_SAMPLE_BRANCH_STACK) {
+			if (branch_sample_hw_index(event))
+				size += sizeof(u64);
+
+			size += data->br_stack->nr
+			      * sizeof(struct perf_branch_entry);
+		}
+		header->size += size;
+	}
+
+	if (sample_type & (PERF_SAMPLE_REGS_USER | PERF_SAMPLE_STACK_USER))
+		perf_sample_regs_user(&data->regs_user, regs);
+
+	if (sample_type & PERF_SAMPLE_REGS_USER) {
+		/* regs dump ABI info */
+		int size = sizeof(u64);
+
+		if (data->regs_user.regs) {
+			u64 mask = event->attr.sample_regs_user;
+			size += hweight64(mask) * sizeof(u64);
+		}
+
+		header->size += size;
+	}
+
+	if (sample_type & PERF_SAMPLE_STACK_USER) {
+		/*
+		 * Either we need PERF_SAMPLE_STACK_USER bit to be always
+		 * processed as the last one or have additional check added
+		 * in case new sample type is added, because we could eat
+		 * up the rest of the sample size.
+		 */
+		u16 stack_size = event->attr.sample_stack_user;
+		u16 size = sizeof(u64);
+
+		stack_size = perf_sample_ustack_size(stack_size, header->size,
+						     data->regs_user.regs);
+
+		/*
+		 * If there is something to dump, add space for the dump
+		 * itself and for the field that tells the dynamic size,
+		 * which is how many have been actually dumped.
+		 */
+		if (stack_size)
+			size += sizeof(u64) + stack_size;
+
+		data->stack_user_size = stack_size;
+		header->size += size;
+	}
+
+	if (filtered_sample_type & PERF_SAMPLE_WEIGHT_TYPE)
+		data->weight.full = 0;
+
+	if (filtered_sample_type & PERF_SAMPLE_DATA_SRC)
+		data->data_src.val = PERF_MEM_NA;
+
+	if (filtered_sample_type & PERF_SAMPLE_TRANSACTION)
+		data->txn = 0;
+
+	if (sample_type & (PERF_SAMPLE_ADDR | PERF_SAMPLE_PHYS_ADDR | PERF_SAMPLE_DATA_PAGE_SIZE)) {
+		if (filtered_sample_type & PERF_SAMPLE_ADDR)
+			data->addr = 0;
+	}
+
+	if (sample_type & PERF_SAMPLE_REGS_INTR) {
+		/* regs dump ABI info */
+		int size = sizeof(u64);
+
+		perf_sample_regs_intr(&data->regs_intr, regs);
+
+		if (data->regs_intr.regs) {
+			u64 mask = event->attr.sample_regs_intr;
+
+			size += hweight64(mask) * sizeof(u64);
+		}
+
+		header->size += size;
+	}
+
+	if (sample_type & PERF_SAMPLE_PHYS_ADDR &&
+	    filtered_sample_type & PERF_SAMPLE_PHYS_ADDR)
+		data->phys_addr = perf_virt_to_phys(data->addr);
+
+#ifdef CONFIG_CGROUP_PERF
+	if (sample_type & PERF_SAMPLE_CGROUP) {
+		struct cgroup *cgrp;
+
+		/* protected by RCU */
+		cgrp = task_css_check(current, perf_event_cgrp_id, 1)->cgroup;
+		data->cgroup = cgroup_id(cgrp);
+	}
+#endif
+
+	/*
+	 * PERF_DATA_PAGE_SIZE requires PERF_SAMPLE_ADDR. If the user doesn't
+	 * require PERF_SAMPLE_ADDR, kernel implicitly retrieve the data->addr,
+	 * but the value will not dump to the userspace.
+	 */
+	if (sample_type & PERF_SAMPLE_DATA_PAGE_SIZE)
+		data->data_page_size = perf_get_page_size(data->addr);
+
+	if (sample_type & PERF_SAMPLE_CODE_PAGE_SIZE)
+		data->code_page_size = perf_get_page_size(data->ip);
+
+	if (sample_type & PERF_SAMPLE_AUX) {
+		u64 size;
+
+		header->size += sizeof(u64); /* size */
+
+		/*
+		 * Given the 16bit nature of header::size, an AUX sample can
+		 * easily overflow it, what with all the preceding sample bits.
+		 * Make sure this doesn't happen by using up to U16_MAX bytes
+		 * per sample in total (rounded down to 8 byte boundary).
+		 */
+		size = min_t(size_t, U16_MAX - header->size,
+			     event->attr.aux_sample_size);
+		size = rounddown(size, 8);
+		size = perf_prepare_sample_aux(event, data, size);
+
+		WARN_ON_ONCE(size + header->size > U16_MAX);
+		header->size += size;
+	}
+	/*
+	 * If you're adding more sample types here, you likely need to do
+	 * something about the overflowing header::size, like repurpose the
+	 * lowest 3 bits of size, which should be always zero at the moment.
+	 * This raises a more important question, do we really need 512k sized
+	 * samples and why, so good argumentation is in order for whatever you
+	 * do here next.
+	 */
+	WARN_ON_ONCE(header->size & 7);
+}
+
+static __always_inline int
+__perf_event_output(struct perf_event *event,
+		    struct perf_sample_data *data,
+		    struct pt_regs *regs,
+		    int (*output_begin)(struct perf_output_handle *,
+					struct perf_sample_data *,
+					struct perf_event *,
+					unsigned int))
+{
+	struct perf_output_handle handle;
+	struct perf_event_header header;
+	int err;
+
+	/* protect the callchain buffers */
+	rcu_read_lock();
+
+	perf_prepare_sample(&header, data, event, regs);
+
+	err = output_begin(&handle, data, event, header.size);
+	if (err)
+		goto exit;
+
+	perf_output_sample(&handle, &header, data, event);
+
+	perf_output_end(&handle);
+
+exit:
+	rcu_read_unlock();
+	return err;
+}
+
+void
+perf_event_output_forward(struct perf_event *event,
+			 struct perf_sample_data *data,
+			 struct pt_regs *regs)
+{
+	__perf_event_output(event, data, regs, perf_output_begin_forward);
+}
+
+void
+perf_event_output_backward(struct perf_event *event,
+			   struct perf_sample_data *data,
+			   struct pt_regs *regs)
+{
+	__perf_event_output(event, data, regs, perf_output_begin_backward);
+}
+
+int
+perf_event_output(struct perf_event *event,
+		  struct perf_sample_data *data,
+		  struct pt_regs *regs)
+{
+	return __perf_event_output(event, data, regs, perf_output_begin);
+}
+
+/*
+ * read event_id
+ */
+
+struct perf_read_event {
+	struct perf_event_header	header;
+
+	u32				pid;
+	u32				tid;
+};
+
+static void
+perf_event_read_event(struct perf_event *event,
+			struct task_struct *task)
+{
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	struct perf_read_event read_event = {
+		.header = {
+			.type = PERF_RECORD_READ,
+			.misc = 0,
+			.size = sizeof(read_event) + event->read_size,
+		},
+		.pid = perf_event_pid(event, task),
+		.tid = perf_event_tid(event, task),
+	};
+	int ret;
+
+	perf_event_header__init_id(&read_event.header, &sample, event);
+	ret = perf_output_begin(&handle, &sample, event, read_event.header.size);
+	if (ret)
+		return;
+
+	perf_output_put(&handle, read_event);
+	perf_output_read(&handle, event);
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+}
+
+typedef void (perf_iterate_f)(struct perf_event *event, void *data);
+
+static void
+perf_iterate_ctx(struct perf_event_context *ctx,
+		   perf_iterate_f output,
+		   void *data, bool all)
+{
+	struct perf_event *event;
+
+	list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+		if (!all) {
+			if (event->state < PERF_EVENT_STATE_INACTIVE)
+				continue;
+			if (!event_filter_match(event))
+				continue;
+		}
+
+		output(event, data);
+	}
+}
+
+static void perf_iterate_sb_cpu(perf_iterate_f output, void *data)
+{
+	struct pmu_event_list *pel = this_cpu_ptr(&pmu_sb_events);
+	struct perf_event *event;
+
+	list_for_each_entry_rcu(event, &pel->list, sb_list) {
+		/*
+		 * Skip events that are not fully formed yet; ensure that
+		 * if we observe event->ctx, both event and ctx will be
+		 * complete enough. See perf_install_in_context().
+		 */
+		if (!smp_load_acquire(&event->ctx))
+			continue;
+
+		if (event->state < PERF_EVENT_STATE_INACTIVE)
+			continue;
+		if (!event_filter_match(event))
+			continue;
+		output(event, data);
+	}
+}
+
+/*
+ * Iterate all events that need to receive side-band events.
+ *
+ * For new callers; ensure that account_pmu_sb_event() includes
+ * your event, otherwise it might not get delivered.
+ */
+static void
+perf_iterate_sb(perf_iterate_f output, void *data,
+	       struct perf_event_context *task_ctx)
+{
+	struct perf_event_context *ctx;
+	int ctxn;
+
+	rcu_read_lock();
+	preempt_disable();
+
+	/*
+	 * If we have task_ctx != NULL we only notify the task context itself.
+	 * The task_ctx is set only for EXIT events before releasing task
+	 * context.
+	 */
+	if (task_ctx) {
+		perf_iterate_ctx(task_ctx, output, data, false);
+		goto done;
+	}
+
+	perf_iterate_sb_cpu(output, data);
+
+	for_each_task_context_nr(ctxn) {
+		ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
+		if (ctx)
+			perf_iterate_ctx(ctx, output, data, false);
+	}
+done:
+	preempt_enable();
+	rcu_read_unlock();
+}
+
+/*
+ * Clear all file-based filters at exec, they'll have to be
+ * re-instated when/if these objects are mmapped again.
+ */
+static void perf_event_addr_filters_exec(struct perf_event *event, void *data)
+{
+	struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
+	struct perf_addr_filter *filter;
+	unsigned int restart = 0, count = 0;
+	unsigned long flags;
+
+	if (!has_addr_filter(event))
+		return;
+
+	raw_spin_lock_irqsave(&ifh->lock, flags);
+	list_for_each_entry(filter, &ifh->list, entry) {
+		if (filter->path.dentry) {
+			event->addr_filter_ranges[count].start = 0;
+			event->addr_filter_ranges[count].size = 0;
+			restart++;
+		}
+
+		count++;
+	}
+
+	if (restart)
+		event->addr_filters_gen++;
+	raw_spin_unlock_irqrestore(&ifh->lock, flags);
+
+	if (restart)
+		perf_event_stop(event, 1);
+}
+
+void perf_event_exec(void)
+{
+	struct perf_event_context *ctx;
+	int ctxn;
+
+	for_each_task_context_nr(ctxn) {
+		perf_event_enable_on_exec(ctxn);
+		perf_event_remove_on_exec(ctxn);
+
+		rcu_read_lock();
+		ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
+		if (ctx) {
+			perf_iterate_ctx(ctx, perf_event_addr_filters_exec,
+					 NULL, true);
+		}
+		rcu_read_unlock();
+	}
+}
+
+struct remote_output {
+	struct perf_buffer	*rb;
+	int			err;
+};
+
+static void __perf_event_output_stop(struct perf_event *event, void *data)
+{
+	struct perf_event *parent = event->parent;
+	struct remote_output *ro = data;
+	struct perf_buffer *rb = ro->rb;
+	struct stop_event_data sd = {
+		.event	= event,
+	};
+
+	if (!has_aux(event))
+		return;
+
+	if (!parent)
+		parent = event;
+
+	/*
+	 * In case of inheritance, it will be the parent that links to the
+	 * ring-buffer, but it will be the child that's actually using it.
+	 *
+	 * We are using event::rb to determine if the event should be stopped,
+	 * however this may race with ring_buffer_attach() (through set_output),
+	 * which will make us skip the event that actually needs to be stopped.
+	 * So ring_buffer_attach() has to stop an aux event before re-assigning
+	 * its rb pointer.
+	 */
+	if (rcu_dereference(parent->rb) == rb)
+		ro->err = __perf_event_stop(&sd);
+}
+
+static int __perf_pmu_output_stop(void *info)
+{
+	struct perf_event *event = info;
+	struct pmu *pmu = event->ctx->pmu;
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+	struct remote_output ro = {
+		.rb	= event->rb,
+	};
+
+	rcu_read_lock();
+	perf_iterate_ctx(&cpuctx->ctx, __perf_event_output_stop, &ro, false);
+	if (cpuctx->task_ctx)
+		perf_iterate_ctx(cpuctx->task_ctx, __perf_event_output_stop,
+				   &ro, false);
+	rcu_read_unlock();
+
+	return ro.err;
+}
+
+static void perf_pmu_output_stop(struct perf_event *event)
+{
+	struct perf_event *iter;
+	int err, cpu;
+
+restart:
+	rcu_read_lock();
+	list_for_each_entry_rcu(iter, &event->rb->event_list, rb_entry) {
+		/*
+		 * For per-CPU events, we need to make sure that neither they
+		 * nor their children are running; for cpu==-1 events it's
+		 * sufficient to stop the event itself if it's active, since
+		 * it can't have children.
+		 */
+		cpu = iter->cpu;
+		if (cpu == -1)
+			cpu = READ_ONCE(iter->oncpu);
+
+		if (cpu == -1)
+			continue;
+
+		err = cpu_function_call(cpu, __perf_pmu_output_stop, event);
+		if (err == -EAGAIN) {
+			rcu_read_unlock();
+			goto restart;
+		}
+	}
+	rcu_read_unlock();
+}
+
+/*
+ * task tracking -- fork/exit
+ *
+ * enabled by: attr.comm | attr.mmap | attr.mmap2 | attr.mmap_data | attr.task
+ */
+
+struct perf_task_event {
+	struct task_struct		*task;
+	struct perf_event_context	*task_ctx;
+
+	struct {
+		struct perf_event_header	header;
+
+		u32				pid;
+		u32				ppid;
+		u32				tid;
+		u32				ptid;
+		u64				time;
+	} event_id;
+};
+
+static int perf_event_task_match(struct perf_event *event)
+{
+	return event->attr.comm  || event->attr.mmap ||
+	       event->attr.mmap2 || event->attr.mmap_data ||
+	       event->attr.task;
+}
+
+static void perf_event_task_output(struct perf_event *event,
+				   void *data)
+{
+	struct perf_task_event *task_event = data;
+	struct perf_output_handle handle;
+	struct perf_sample_data	sample;
+	struct task_struct *task = task_event->task;
+	int ret, size = task_event->event_id.header.size;
+
+	if (!perf_event_task_match(event))
+		return;
+
+	perf_event_header__init_id(&task_event->event_id.header, &sample, event);
+
+	ret = perf_output_begin(&handle, &sample, event,
+				task_event->event_id.header.size);
+	if (ret)
+		goto out;
+
+	task_event->event_id.pid = perf_event_pid(event, task);
+	task_event->event_id.tid = perf_event_tid(event, task);
+
+	if (task_event->event_id.header.type == PERF_RECORD_EXIT) {
+		task_event->event_id.ppid = perf_event_pid(event,
+							task->real_parent);
+		task_event->event_id.ptid = perf_event_pid(event,
+							task->real_parent);
+	} else {  /* PERF_RECORD_FORK */
+		task_event->event_id.ppid = perf_event_pid(event, current);
+		task_event->event_id.ptid = perf_event_tid(event, current);
+	}
+
+	task_event->event_id.time = perf_event_clock(event);
+
+	perf_output_put(&handle, task_event->event_id);
+
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+out:
+	task_event->event_id.header.size = size;
+}
+
+static void perf_event_task(struct task_struct *task,
+			      struct perf_event_context *task_ctx,
+			      int new)
+{
+	struct perf_task_event task_event;
+
+	if (!atomic_read(&nr_comm_events) &&
+	    !atomic_read(&nr_mmap_events) &&
+	    !atomic_read(&nr_task_events))
+		return;
+
+	task_event = (struct perf_task_event){
+		.task	  = task,
+		.task_ctx = task_ctx,
+		.event_id    = {
+			.header = {
+				.type = new ? PERF_RECORD_FORK : PERF_RECORD_EXIT,
+				.misc = 0,
+				.size = sizeof(task_event.event_id),
+			},
+			/* .pid  */
+			/* .ppid */
+			/* .tid  */
+			/* .ptid */
+			/* .time */
+		},
+	};
+
+	perf_iterate_sb(perf_event_task_output,
+		       &task_event,
+		       task_ctx);
+}
+
+void perf_event_fork(struct task_struct *task)
+{
+	perf_event_task(task, NULL, 1);
+	perf_event_namespaces(task);
+}
+
+/*
+ * comm tracking
+ */
+
+struct perf_comm_event {
+	struct task_struct	*task;
+	char			*comm;
+	int			comm_size;
+
+	struct {
+		struct perf_event_header	header;
+
+		u32				pid;
+		u32				tid;
+	} event_id;
+};
+
+static int perf_event_comm_match(struct perf_event *event)
+{
+	return event->attr.comm;
+}
+
+static void perf_event_comm_output(struct perf_event *event,
+				   void *data)
+{
+	struct perf_comm_event *comm_event = data;
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	int size = comm_event->event_id.header.size;
+	int ret;
+
+	if (!perf_event_comm_match(event))
+		return;
+
+	perf_event_header__init_id(&comm_event->event_id.header, &sample, event);
+	ret = perf_output_begin(&handle, &sample, event,
+				comm_event->event_id.header.size);
+
+	if (ret)
+		goto out;
+
+	comm_event->event_id.pid = perf_event_pid(event, comm_event->task);
+	comm_event->event_id.tid = perf_event_tid(event, comm_event->task);
+
+	perf_output_put(&handle, comm_event->event_id);
+	__output_copy(&handle, comm_event->comm,
+				   comm_event->comm_size);
+
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+out:
+	comm_event->event_id.header.size = size;
+}
+
+static void perf_event_comm_event(struct perf_comm_event *comm_event)
+{
+	char comm[TASK_COMM_LEN];
+	unsigned int size;
+
+	memset(comm, 0, sizeof(comm));
+	strlcpy(comm, comm_event->task->comm, sizeof(comm));
+	size = ALIGN(strlen(comm)+1, sizeof(u64));
+
+	comm_event->comm = comm;
+	comm_event->comm_size = size;
+
+	comm_event->event_id.header.size = sizeof(comm_event->event_id) + size;
+
+	perf_iterate_sb(perf_event_comm_output,
+		       comm_event,
+		       NULL);
+}
+
+void perf_event_comm(struct task_struct *task, bool exec)
+{
+	struct perf_comm_event comm_event;
+
+	if (!atomic_read(&nr_comm_events))
+		return;
+
+	comm_event = (struct perf_comm_event){
+		.task	= task,
+		/* .comm      */
+		/* .comm_size */
+		.event_id  = {
+			.header = {
+				.type = PERF_RECORD_COMM,
+				.misc = exec ? PERF_RECORD_MISC_COMM_EXEC : 0,
+				/* .size */
+			},
+			/* .pid */
+			/* .tid */
+		},
+	};
+
+	perf_event_comm_event(&comm_event);
+}
+
+/*
+ * namespaces tracking
+ */
+
+struct perf_namespaces_event {
+	struct task_struct		*task;
+
+	struct {
+		struct perf_event_header	header;
+
+		u32				pid;
+		u32				tid;
+		u64				nr_namespaces;
+		struct perf_ns_link_info	link_info[NR_NAMESPACES];
+	} event_id;
+};
+
+static int perf_event_namespaces_match(struct perf_event *event)
+{
+	return event->attr.namespaces;
+}
+
+static void perf_event_namespaces_output(struct perf_event *event,
+					 void *data)
+{
+	struct perf_namespaces_event *namespaces_event = data;
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	u16 header_size = namespaces_event->event_id.header.size;
+	int ret;
+
+	if (!perf_event_namespaces_match(event))
+		return;
+
+	perf_event_header__init_id(&namespaces_event->event_id.header,
+				   &sample, event);
+	ret = perf_output_begin(&handle, &sample, event,
+				namespaces_event->event_id.header.size);
+	if (ret)
+		goto out;
+
+	namespaces_event->event_id.pid = perf_event_pid(event,
+							namespaces_event->task);
+	namespaces_event->event_id.tid = perf_event_tid(event,
+							namespaces_event->task);
+
+	perf_output_put(&handle, namespaces_event->event_id);
+
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+out:
+	namespaces_event->event_id.header.size = header_size;
+}
+
+static void perf_fill_ns_link_info(struct perf_ns_link_info *ns_link_info,
+				   struct task_struct *task,
+				   const struct proc_ns_operations *ns_ops)
+{
+	struct path ns_path;
+	struct inode *ns_inode;
+	int error;
+
+	error = ns_get_path(&ns_path, task, ns_ops);
+	if (!error) {
+		ns_inode = ns_path.dentry->d_inode;
+		ns_link_info->dev = new_encode_dev(ns_inode->i_sb->s_dev);
+		ns_link_info->ino = ns_inode->i_ino;
+		path_put(&ns_path);
+	}
+}
+
+void perf_event_namespaces(struct task_struct *task)
+{
+	struct perf_namespaces_event namespaces_event;
+	struct perf_ns_link_info *ns_link_info;
+
+	if (!atomic_read(&nr_namespaces_events))
+		return;
+
+	namespaces_event = (struct perf_namespaces_event){
+		.task	= task,
+		.event_id  = {
+			.header = {
+				.type = PERF_RECORD_NAMESPACES,
+				.misc = 0,
+				.size = sizeof(namespaces_event.event_id),
+			},
+			/* .pid */
+			/* .tid */
+			.nr_namespaces = NR_NAMESPACES,
+			/* .link_info[NR_NAMESPACES] */
+		},
+	};
+
+	ns_link_info = namespaces_event.event_id.link_info;
+
+	perf_fill_ns_link_info(&ns_link_info[MNT_NS_INDEX],
+			       task, &mntns_operations);
+
+#ifdef CONFIG_USER_NS
+	perf_fill_ns_link_info(&ns_link_info[USER_NS_INDEX],
+			       task, &userns_operations);
+#endif
+#ifdef CONFIG_NET_NS
+	perf_fill_ns_link_info(&ns_link_info[NET_NS_INDEX],
+			       task, &netns_operations);
+#endif
+#ifdef CONFIG_UTS_NS
+	perf_fill_ns_link_info(&ns_link_info[UTS_NS_INDEX],
+			       task, &utsns_operations);
+#endif
+#ifdef CONFIG_IPC_NS
+	perf_fill_ns_link_info(&ns_link_info[IPC_NS_INDEX],
+			       task, &ipcns_operations);
+#endif
+#ifdef CONFIG_PID_NS
+	perf_fill_ns_link_info(&ns_link_info[PID_NS_INDEX],
+			       task, &pidns_operations);
+#endif
+#ifdef CONFIG_CGROUPS
+	perf_fill_ns_link_info(&ns_link_info[CGROUP_NS_INDEX],
+			       task, &cgroupns_operations);
+#endif
+
+	perf_iterate_sb(perf_event_namespaces_output,
+			&namespaces_event,
+			NULL);
+}
+
+/*
+ * cgroup tracking
+ */
+#ifdef CONFIG_CGROUP_PERF
+
+struct perf_cgroup_event {
+	char				*path;
+	int				path_size;
+	struct {
+		struct perf_event_header	header;
+		u64				id;
+		char				path[];
+	} event_id;
+};
+
+static int perf_event_cgroup_match(struct perf_event *event)
+{
+	return event->attr.cgroup;
+}
+
+static void perf_event_cgroup_output(struct perf_event *event, void *data)
+{
+	struct perf_cgroup_event *cgroup_event = data;
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	u16 header_size = cgroup_event->event_id.header.size;
+	int ret;
+
+	if (!perf_event_cgroup_match(event))
+		return;
+
+	perf_event_header__init_id(&cgroup_event->event_id.header,
+				   &sample, event);
+	ret = perf_output_begin(&handle, &sample, event,
+				cgroup_event->event_id.header.size);
+	if (ret)
+		goto out;
+
+	perf_output_put(&handle, cgroup_event->event_id);
+	__output_copy(&handle, cgroup_event->path, cgroup_event->path_size);
+
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+out:
+	cgroup_event->event_id.header.size = header_size;
+}
+
+static void perf_event_cgroup(struct cgroup *cgrp)
+{
+	struct perf_cgroup_event cgroup_event;
+	char path_enomem[16] = "//enomem";
+	char *pathname;
+	size_t size;
+
+	if (!atomic_read(&nr_cgroup_events))
+		return;
+
+	cgroup_event = (struct perf_cgroup_event){
+		.event_id  = {
+			.header = {
+				.type = PERF_RECORD_CGROUP,
+				.misc = 0,
+				.size = sizeof(cgroup_event.event_id),
+			},
+			.id = cgroup_id(cgrp),
+		},
+	};
+
+	pathname = kmalloc(PATH_MAX, GFP_KERNEL);
+	if (pathname == NULL) {
+		cgroup_event.path = path_enomem;
+	} else {
+		/* just to be sure to have enough space for alignment */
+		cgroup_path(cgrp, pathname, PATH_MAX - sizeof(u64));
+		cgroup_event.path = pathname;
+	}
+
+	/*
+	 * Since our buffer works in 8 byte units we need to align our string
+	 * size to a multiple of 8. However, we must guarantee the tail end is
+	 * zero'd out to avoid leaking random bits to userspace.
+	 */
+	size = strlen(cgroup_event.path) + 1;
+	while (!IS_ALIGNED(size, sizeof(u64)))
+		cgroup_event.path[size++] = '\0';
+
+	cgroup_event.event_id.header.size += size;
+	cgroup_event.path_size = size;
+
+	perf_iterate_sb(perf_event_cgroup_output,
+			&cgroup_event,
+			NULL);
+
+	kfree(pathname);
+}
+
+#endif
+
+/*
+ * mmap tracking
+ */
+
+struct perf_mmap_event {
+	struct vm_area_struct	*vma;
+
+	const char		*file_name;
+	int			file_size;
+	int			maj, min;
+	u64			ino;
+	u64			ino_generation;
+	u32			prot, flags;
+	u8			build_id[BUILD_ID_SIZE_MAX];
+	u32			build_id_size;
+
+	struct {
+		struct perf_event_header	header;
+
+		u32				pid;
+		u32				tid;
+		u64				start;
+		u64				len;
+		u64				pgoff;
+	} event_id;
+};
+
+static int perf_event_mmap_match(struct perf_event *event,
+				 void *data)
+{
+	struct perf_mmap_event *mmap_event = data;
+	struct vm_area_struct *vma = mmap_event->vma;
+	int executable = vma->vm_flags & VM_EXEC;
+
+	return (!executable && event->attr.mmap_data) ||
+	       (executable && (event->attr.mmap || event->attr.mmap2));
+}
+
+static void perf_event_mmap_output(struct perf_event *event,
+				   void *data)
+{
+	struct perf_mmap_event *mmap_event = data;
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	int size = mmap_event->event_id.header.size;
+	u32 type = mmap_event->event_id.header.type;
+	bool use_build_id;
+	int ret;
+
+	if (!perf_event_mmap_match(event, data))
+		return;
+
+	if (event->attr.mmap2) {
+		mmap_event->event_id.header.type = PERF_RECORD_MMAP2;
+		mmap_event->event_id.header.size += sizeof(mmap_event->maj);
+		mmap_event->event_id.header.size += sizeof(mmap_event->min);
+		mmap_event->event_id.header.size += sizeof(mmap_event->ino);
+		mmap_event->event_id.header.size += sizeof(mmap_event->ino_generation);
+		mmap_event->event_id.header.size += sizeof(mmap_event->prot);
+		mmap_event->event_id.header.size += sizeof(mmap_event->flags);
+	}
+
+	perf_event_header__init_id(&mmap_event->event_id.header, &sample, event);
+	ret = perf_output_begin(&handle, &sample, event,
+				mmap_event->event_id.header.size);
+	if (ret)
+		goto out;
+
+	mmap_event->event_id.pid = perf_event_pid(event, current);
+	mmap_event->event_id.tid = perf_event_tid(event, current);
+
+	use_build_id = event->attr.build_id && mmap_event->build_id_size;
+
+	if (event->attr.mmap2 && use_build_id)
+		mmap_event->event_id.header.misc |= PERF_RECORD_MISC_MMAP_BUILD_ID;
+
+	perf_output_put(&handle, mmap_event->event_id);
+
+	if (event->attr.mmap2) {
+		if (use_build_id) {
+			u8 size[4] = { (u8) mmap_event->build_id_size, 0, 0, 0 };
+
+			__output_copy(&handle, size, 4);
+			__output_copy(&handle, mmap_event->build_id, BUILD_ID_SIZE_MAX);
+		} else {
+			perf_output_put(&handle, mmap_event->maj);
+			perf_output_put(&handle, mmap_event->min);
+			perf_output_put(&handle, mmap_event->ino);
+			perf_output_put(&handle, mmap_event->ino_generation);
+		}
+		perf_output_put(&handle, mmap_event->prot);
+		perf_output_put(&handle, mmap_event->flags);
+	}
+
+	__output_copy(&handle, mmap_event->file_name,
+				   mmap_event->file_size);
+
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+out:
+	mmap_event->event_id.header.size = size;
+	mmap_event->event_id.header.type = type;
+}
+
+static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
+{
+	struct vm_area_struct *vma = mmap_event->vma;
+	struct file *file = vma->vm_file;
+	int maj = 0, min = 0;
+	u64 ino = 0, gen = 0;
+	u32 prot = 0, flags = 0;
+	unsigned int size;
+	char tmp[16];
+	char *buf = NULL;
+	char *name;
+
+	if (vma->vm_flags & VM_READ)
+		prot |= PROT_READ;
+	if (vma->vm_flags & VM_WRITE)
+		prot |= PROT_WRITE;
+	if (vma->vm_flags & VM_EXEC)
+		prot |= PROT_EXEC;
+
+	if (vma->vm_flags & VM_MAYSHARE)
+		flags = MAP_SHARED;
+	else
+		flags = MAP_PRIVATE;
+
+	if (vma->vm_flags & VM_LOCKED)
+		flags |= MAP_LOCKED;
+	if (is_vm_hugetlb_page(vma))
+		flags |= MAP_HUGETLB;
+
+	if (file) {
+		struct inode *inode;
+		dev_t dev;
+
+		buf = kmalloc(PATH_MAX, GFP_KERNEL);
+		if (!buf) {
+			name = "//enomem";
+			goto cpy_name;
+		}
+		/*
+		 * d_path() works from the end of the rb backwards, so we
+		 * need to add enough zero bytes after the string to handle
+		 * the 64bit alignment we do later.
+		 */
+		name = file_path(file, buf, PATH_MAX - sizeof(u64));
+		if (IS_ERR(name)) {
+			name = "//toolong";
+			goto cpy_name;
+		}
+		inode = file_inode(vma->vm_file);
+		dev = inode->i_sb->s_dev;
+		ino = inode->i_ino;
+		gen = inode->i_generation;
+		maj = MAJOR(dev);
+		min = MINOR(dev);
+
+		goto got_name;
+	} else {
+		if (vma->vm_ops && vma->vm_ops->name) {
+			name = (char *) vma->vm_ops->name(vma);
+			if (name)
+				goto cpy_name;
+		}
+
+		name = (char *)arch_vma_name(vma);
+		if (name)
+			goto cpy_name;
+
+		if (vma->vm_start <= vma->vm_mm->start_brk &&
+				vma->vm_end >= vma->vm_mm->brk) {
+			name = "[heap]";
+			goto cpy_name;
+		}
+		if (vma->vm_start <= vma->vm_mm->start_stack &&
+				vma->vm_end >= vma->vm_mm->start_stack) {
+			name = "[stack]";
+			goto cpy_name;
+		}
+
+		name = "//anon";
+		goto cpy_name;
+	}
+
+cpy_name:
+	strlcpy(tmp, name, sizeof(tmp));
+	name = tmp;
+got_name:
+	/*
+	 * Since our buffer works in 8 byte units we need to align our string
+	 * size to a multiple of 8. However, we must guarantee the tail end is
+	 * zero'd out to avoid leaking random bits to userspace.
+	 */
+	size = strlen(name)+1;
+	while (!IS_ALIGNED(size, sizeof(u64)))
+		name[size++] = '\0';
+
+	mmap_event->file_name = name;
+	mmap_event->file_size = size;
+	mmap_event->maj = maj;
+	mmap_event->min = min;
+	mmap_event->ino = ino;
+	mmap_event->ino_generation = gen;
+	mmap_event->prot = prot;
+	mmap_event->flags = flags;
+
+	if (!(vma->vm_flags & VM_EXEC))
+		mmap_event->event_id.header.misc |= PERF_RECORD_MISC_MMAP_DATA;
+
+	mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size;
+
+	if (atomic_read(&nr_build_id_events))
+		build_id_parse(vma, mmap_event->build_id, &mmap_event->build_id_size);
+
+	perf_iterate_sb(perf_event_mmap_output,
+		       mmap_event,
+		       NULL);
+
+	kfree(buf);
+}
+
+/*
+ * Check whether inode and address range match filter criteria.
+ */
+static bool perf_addr_filter_match(struct perf_addr_filter *filter,
+				     struct file *file, unsigned long offset,
+				     unsigned long size)
+{
+	/* d_inode(NULL) won't be equal to any mapped user-space file */
+	if (!filter->path.dentry)
+		return false;
+
+	if (d_inode(filter->path.dentry) != file_inode(file))
+		return false;
+
+	if (filter->offset > offset + size)
+		return false;
+
+	if (filter->offset + filter->size < offset)
+		return false;
+
+	return true;
+}
+
+static bool perf_addr_filter_vma_adjust(struct perf_addr_filter *filter,
+					struct vm_area_struct *vma,
+					struct perf_addr_filter_range *fr)
+{
+	unsigned long vma_size = vma->vm_end - vma->vm_start;
+	unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
+	struct file *file = vma->vm_file;
+
+	if (!perf_addr_filter_match(filter, file, off, vma_size))
+		return false;
+
+	if (filter->offset < off) {
+		fr->start = vma->vm_start;
+		fr->size = min(vma_size, filter->size - (off - filter->offset));
+	} else {
+		fr->start = vma->vm_start + filter->offset - off;
+		fr->size = min(vma->vm_end - fr->start, filter->size);
+	}
+
+	return true;
+}
+
+static void __perf_addr_filters_adjust(struct perf_event *event, void *data)
+{
+	struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
+	struct vm_area_struct *vma = data;
+	struct perf_addr_filter *filter;
+	unsigned int restart = 0, count = 0;
+	unsigned long flags;
+
+	if (!has_addr_filter(event))
+		return;
+
+	if (!vma->vm_file)
+		return;
+
+	raw_spin_lock_irqsave(&ifh->lock, flags);
+	list_for_each_entry(filter, &ifh->list, entry) {
+		if (perf_addr_filter_vma_adjust(filter, vma,
+						&event->addr_filter_ranges[count]))
+			restart++;
+
+		count++;
+	}
+
+	if (restart)
+		event->addr_filters_gen++;
+	raw_spin_unlock_irqrestore(&ifh->lock, flags);
+
+	if (restart)
+		perf_event_stop(event, 1);
+}
+
+/*
+ * Adjust all task's events' filters to the new vma
+ */
+static void perf_addr_filters_adjust(struct vm_area_struct *vma)
+{
+	struct perf_event_context *ctx;
+	int ctxn;
+
+	/*
+	 * Data tracing isn't supported yet and as such there is no need
+	 * to keep track of anything that isn't related to executable code:
+	 */
+	if (!(vma->vm_flags & VM_EXEC))
+		return;
+
+	rcu_read_lock();
+	for_each_task_context_nr(ctxn) {
+		ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
+		if (!ctx)
+			continue;
+
+		perf_iterate_ctx(ctx, __perf_addr_filters_adjust, vma, true);
+	}
+	rcu_read_unlock();
+}
+
+void perf_event_mmap(struct vm_area_struct *vma)
+{
+	struct perf_mmap_event mmap_event;
+
+	if (!atomic_read(&nr_mmap_events))
+		return;
+
+	mmap_event = (struct perf_mmap_event){
+		.vma	= vma,
+		/* .file_name */
+		/* .file_size */
+		.event_id  = {
+			.header = {
+				.type = PERF_RECORD_MMAP,
+				.misc = PERF_RECORD_MISC_USER,
+				/* .size */
+			},
+			/* .pid */
+			/* .tid */
+			.start  = vma->vm_start,
+			.len    = vma->vm_end - vma->vm_start,
+			.pgoff  = (u64)vma->vm_pgoff << PAGE_SHIFT,
+		},
+		/* .maj (attr_mmap2 only) */
+		/* .min (attr_mmap2 only) */
+		/* .ino (attr_mmap2 only) */
+		/* .ino_generation (attr_mmap2 only) */
+		/* .prot (attr_mmap2 only) */
+		/* .flags (attr_mmap2 only) */
+	};
+
+	perf_addr_filters_adjust(vma);
+	perf_event_mmap_event(&mmap_event);
+}
+
+void perf_event_aux_event(struct perf_event *event, unsigned long head,
+			  unsigned long size, u64 flags)
+{
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	struct perf_aux_event {
+		struct perf_event_header	header;
+		u64				offset;
+		u64				size;
+		u64				flags;
+	} rec = {
+		.header = {
+			.type = PERF_RECORD_AUX,
+			.misc = 0,
+			.size = sizeof(rec),
+		},
+		.offset		= head,
+		.size		= size,
+		.flags		= flags,
+	};
+	int ret;
+
+	perf_event_header__init_id(&rec.header, &sample, event);
+	ret = perf_output_begin(&handle, &sample, event, rec.header.size);
+
+	if (ret)
+		return;
+
+	perf_output_put(&handle, rec);
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+}
+
+/*
+ * Lost/dropped samples logging
+ */
+void perf_log_lost_samples(struct perf_event *event, u64 lost)
+{
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	int ret;
+
+	struct {
+		struct perf_event_header	header;
+		u64				lost;
+	} lost_samples_event = {
+		.header = {
+			.type = PERF_RECORD_LOST_SAMPLES,
+			.misc = 0,
+			.size = sizeof(lost_samples_event),
+		},
+		.lost		= lost,
+	};
+
+	perf_event_header__init_id(&lost_samples_event.header, &sample, event);
+
+	ret = perf_output_begin(&handle, &sample, event,
+				lost_samples_event.header.size);
+	if (ret)
+		return;
+
+	perf_output_put(&handle, lost_samples_event);
+	perf_event__output_id_sample(event, &handle, &sample);
+	perf_output_end(&handle);
+}
+
+/*
+ * context_switch tracking
+ */
+
+struct perf_switch_event {
+	struct task_struct	*task;
+	struct task_struct	*next_prev;
+
+	struct {
+		struct perf_event_header	header;
+		u32				next_prev_pid;
+		u32				next_prev_tid;
+	} event_id;
+};
+
+static int perf_event_switch_match(struct perf_event *event)
+{
+	return event->attr.context_switch;
+}
+
+static void perf_event_switch_output(struct perf_event *event, void *data)
+{
+	struct perf_switch_event *se = data;
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	int ret;
+
+	if (!perf_event_switch_match(event))
+		return;
+
+	/* Only CPU-wide events are allowed to see next/prev pid/tid */
+	if (event->ctx->task) {
+		se->event_id.header.type = PERF_RECORD_SWITCH;
+		se->event_id.header.size = sizeof(se->event_id.header);
+	} else {
+		se->event_id.header.type = PERF_RECORD_SWITCH_CPU_WIDE;
+		se->event_id.header.size = sizeof(se->event_id);
+		se->event_id.next_prev_pid =
+					perf_event_pid(event, se->next_prev);
+		se->event_id.next_prev_tid =
+					perf_event_tid(event, se->next_prev);
+	}
+
+	perf_event_header__init_id(&se->event_id.header, &sample, event);
+
+	ret = perf_output_begin(&handle, &sample, event, se->event_id.header.size);
+	if (ret)
+		return;
+
+	if (event->ctx->task)
+		perf_output_put(&handle, se->event_id.header);
+	else
+		perf_output_put(&handle, se->event_id);
+
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+}
+
+static void perf_event_switch(struct task_struct *task,
+			      struct task_struct *next_prev, bool sched_in)
+{
+	struct perf_switch_event switch_event;
+
+	/* N.B. caller checks nr_switch_events != 0 */
+
+	switch_event = (struct perf_switch_event){
+		.task		= task,
+		.next_prev	= next_prev,
+		.event_id	= {
+			.header = {
+				/* .type */
+				.misc = sched_in ? 0 : PERF_RECORD_MISC_SWITCH_OUT,
+				/* .size */
+			},
+			/* .next_prev_pid */
+			/* .next_prev_tid */
+		},
+	};
+
+	if (!sched_in && task->on_rq) {
+		switch_event.event_id.header.misc |=
+				PERF_RECORD_MISC_SWITCH_OUT_PREEMPT;
+	}
+
+	perf_iterate_sb(perf_event_switch_output, &switch_event, NULL);
+}
+
+/*
+ * IRQ throttle logging
+ */
+
+static void perf_log_throttle(struct perf_event *event, int enable)
+{
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	int ret;
+
+	struct {
+		struct perf_event_header	header;
+		u64				time;
+		u64				id;
+		u64				stream_id;
+	} throttle_event = {
+		.header = {
+			.type = PERF_RECORD_THROTTLE,
+			.misc = 0,
+			.size = sizeof(throttle_event),
+		},
+		.time		= perf_event_clock(event),
+		.id		= primary_event_id(event),
+		.stream_id	= event->id,
+	};
+
+	if (enable)
+		throttle_event.header.type = PERF_RECORD_UNTHROTTLE;
+
+	perf_event_header__init_id(&throttle_event.header, &sample, event);
+
+	ret = perf_output_begin(&handle, &sample, event,
+				throttle_event.header.size);
+	if (ret)
+		return;
+
+	perf_output_put(&handle, throttle_event);
+	perf_event__output_id_sample(event, &handle, &sample);
+	perf_output_end(&handle);
+}
+
+/*
+ * ksymbol register/unregister tracking
+ */
+
+struct perf_ksymbol_event {
+	const char	*name;
+	int		name_len;
+	struct {
+		struct perf_event_header        header;
+		u64				addr;
+		u32				len;
+		u16				ksym_type;
+		u16				flags;
+	} event_id;
+};
+
+static int perf_event_ksymbol_match(struct perf_event *event)
+{
+	return event->attr.ksymbol;
+}
+
+static void perf_event_ksymbol_output(struct perf_event *event, void *data)
+{
+	struct perf_ksymbol_event *ksymbol_event = data;
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	int ret;
+
+	if (!perf_event_ksymbol_match(event))
+		return;
+
+	perf_event_header__init_id(&ksymbol_event->event_id.header,
+				   &sample, event);
+	ret = perf_output_begin(&handle, &sample, event,
+				ksymbol_event->event_id.header.size);
+	if (ret)
+		return;
+
+	perf_output_put(&handle, ksymbol_event->event_id);
+	__output_copy(&handle, ksymbol_event->name, ksymbol_event->name_len);
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+}
+
+void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len, bool unregister,
+			const char *sym)
+{
+	struct perf_ksymbol_event ksymbol_event;
+	char name[KSYM_NAME_LEN];
+	u16 flags = 0;
+	int name_len;
+
+	if (!atomic_read(&nr_ksymbol_events))
+		return;
+
+	if (ksym_type >= PERF_RECORD_KSYMBOL_TYPE_MAX ||
+	    ksym_type == PERF_RECORD_KSYMBOL_TYPE_UNKNOWN)
+		goto err;
+
+	strlcpy(name, sym, KSYM_NAME_LEN);
+	name_len = strlen(name) + 1;
+	while (!IS_ALIGNED(name_len, sizeof(u64)))
+		name[name_len++] = '\0';
+	BUILD_BUG_ON(KSYM_NAME_LEN % sizeof(u64));
+
+	if (unregister)
+		flags |= PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER;
+
+	ksymbol_event = (struct perf_ksymbol_event){
+		.name = name,
+		.name_len = name_len,
+		.event_id = {
+			.header = {
+				.type = PERF_RECORD_KSYMBOL,
+				.size = sizeof(ksymbol_event.event_id) +
+					name_len,
+			},
+			.addr = addr,
+			.len = len,
+			.ksym_type = ksym_type,
+			.flags = flags,
+		},
+	};
+
+	perf_iterate_sb(perf_event_ksymbol_output, &ksymbol_event, NULL);
+	return;
+err:
+	WARN_ONCE(1, "%s: Invalid KSYMBOL type 0x%x\n", __func__, ksym_type);
+}
+
+/*
+ * bpf program load/unload tracking
+ */
+
+struct perf_bpf_event {
+	struct bpf_prog	*prog;
+	struct {
+		struct perf_event_header        header;
+		u16				type;
+		u16				flags;
+		u32				id;
+		u8				tag[BPF_TAG_SIZE];
+	} event_id;
+};
+
+static int perf_event_bpf_match(struct perf_event *event)
+{
+	return event->attr.bpf_event;
+}
+
+static void perf_event_bpf_output(struct perf_event *event, void *data)
+{
+	struct perf_bpf_event *bpf_event = data;
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	int ret;
+
+	if (!perf_event_bpf_match(event))
+		return;
+
+	perf_event_header__init_id(&bpf_event->event_id.header,
+				   &sample, event);
+	ret = perf_output_begin(&handle, &sample, event,
+				bpf_event->event_id.header.size);
+	if (ret)
+		return;
+
+	perf_output_put(&handle, bpf_event->event_id);
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+}
+
+static void perf_event_bpf_emit_ksymbols(struct bpf_prog *prog,
+					 enum perf_bpf_event_type type)
+{
+	bool unregister = type == PERF_BPF_EVENT_PROG_UNLOAD;
+	int i;
+
+	if (prog->aux->func_cnt == 0) {
+		perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF,
+				   (u64)(unsigned long)prog->bpf_func,
+				   prog->jited_len, unregister,
+				   prog->aux->ksym.name);
+	} else {
+		for (i = 0; i < prog->aux->func_cnt; i++) {
+			struct bpf_prog *subprog = prog->aux->func[i];
+
+			perf_event_ksymbol(
+				PERF_RECORD_KSYMBOL_TYPE_BPF,
+				(u64)(unsigned long)subprog->bpf_func,
+				subprog->jited_len, unregister,
+				subprog->aux->ksym.name);
+		}
+	}
+}
+
+void perf_event_bpf_event(struct bpf_prog *prog,
+			  enum perf_bpf_event_type type,
+			  u16 flags)
+{
+	struct perf_bpf_event bpf_event;
+
+	if (type <= PERF_BPF_EVENT_UNKNOWN ||
+	    type >= PERF_BPF_EVENT_MAX)
+		return;
+
+	switch (type) {
+	case PERF_BPF_EVENT_PROG_LOAD:
+	case PERF_BPF_EVENT_PROG_UNLOAD:
+		if (atomic_read(&nr_ksymbol_events))
+			perf_event_bpf_emit_ksymbols(prog, type);
+		break;
+	default:
+		break;
+	}
+
+	if (!atomic_read(&nr_bpf_events))
+		return;
+
+	bpf_event = (struct perf_bpf_event){
+		.prog = prog,
+		.event_id = {
+			.header = {
+				.type = PERF_RECORD_BPF_EVENT,
+				.size = sizeof(bpf_event.event_id),
+			},
+			.type = type,
+			.flags = flags,
+			.id = prog->aux->id,
+		},
+	};
+
+	BUILD_BUG_ON(BPF_TAG_SIZE % sizeof(u64));
+
+	memcpy(bpf_event.event_id.tag, prog->tag, BPF_TAG_SIZE);
+	perf_iterate_sb(perf_event_bpf_output, &bpf_event, NULL);
+}
+
+struct perf_text_poke_event {
+	const void		*old_bytes;
+	const void		*new_bytes;
+	size_t			pad;
+	u16			old_len;
+	u16			new_len;
+
+	struct {
+		struct perf_event_header	header;
+
+		u64				addr;
+	} event_id;
+};
+
+static int perf_event_text_poke_match(struct perf_event *event)
+{
+	return event->attr.text_poke;
+}
+
+static void perf_event_text_poke_output(struct perf_event *event, void *data)
+{
+	struct perf_text_poke_event *text_poke_event = data;
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	u64 padding = 0;
+	int ret;
+
+	if (!perf_event_text_poke_match(event))
+		return;
+
+	perf_event_header__init_id(&text_poke_event->event_id.header, &sample, event);
+
+	ret = perf_output_begin(&handle, &sample, event,
+				text_poke_event->event_id.header.size);
+	if (ret)
+		return;
+
+	perf_output_put(&handle, text_poke_event->event_id);
+	perf_output_put(&handle, text_poke_event->old_len);
+	perf_output_put(&handle, text_poke_event->new_len);
+
+	__output_copy(&handle, text_poke_event->old_bytes, text_poke_event->old_len);
+	__output_copy(&handle, text_poke_event->new_bytes, text_poke_event->new_len);
+
+	if (text_poke_event->pad)
+		__output_copy(&handle, &padding, text_poke_event->pad);
+
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+}
+
+void perf_event_text_poke(const void *addr, const void *old_bytes,
+			  size_t old_len, const void *new_bytes, size_t new_len)
+{
+	struct perf_text_poke_event text_poke_event;
+	size_t tot, pad;
+
+	if (!atomic_read(&nr_text_poke_events))
+		return;
+
+	tot  = sizeof(text_poke_event.old_len) + old_len;
+	tot += sizeof(text_poke_event.new_len) + new_len;
+	pad  = ALIGN(tot, sizeof(u64)) - tot;
+
+	text_poke_event = (struct perf_text_poke_event){
+		.old_bytes    = old_bytes,
+		.new_bytes    = new_bytes,
+		.pad          = pad,
+		.old_len      = old_len,
+		.new_len      = new_len,
+		.event_id  = {
+			.header = {
+				.type = PERF_RECORD_TEXT_POKE,
+				.misc = PERF_RECORD_MISC_KERNEL,
+				.size = sizeof(text_poke_event.event_id) + tot + pad,
+			},
+			.addr = (unsigned long)addr,
+		},
+	};
+
+	perf_iterate_sb(perf_event_text_poke_output, &text_poke_event, NULL);
+}
+
+void perf_event_itrace_started(struct perf_event *event)
+{
+	event->attach_state |= PERF_ATTACH_ITRACE;
+}
+
+static void perf_log_itrace_start(struct perf_event *event)
+{
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	struct perf_aux_event {
+		struct perf_event_header        header;
+		u32				pid;
+		u32				tid;
+	} rec;
+	int ret;
+
+	if (event->parent)
+		event = event->parent;
+
+	if (!(event->pmu->capabilities & PERF_PMU_CAP_ITRACE) ||
+	    event->attach_state & PERF_ATTACH_ITRACE)
+		return;
+
+	rec.header.type	= PERF_RECORD_ITRACE_START;
+	rec.header.misc	= 0;
+	rec.header.size	= sizeof(rec);
+	rec.pid	= perf_event_pid(event, current);
+	rec.tid	= perf_event_tid(event, current);
+
+	perf_event_header__init_id(&rec.header, &sample, event);
+	ret = perf_output_begin(&handle, &sample, event, rec.header.size);
+
+	if (ret)
+		return;
+
+	perf_output_put(&handle, rec);
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+}
+
+void perf_report_aux_output_id(struct perf_event *event, u64 hw_id)
+{
+	struct perf_output_handle handle;
+	struct perf_sample_data sample;
+	struct perf_aux_event {
+		struct perf_event_header        header;
+		u64				hw_id;
+	} rec;
+	int ret;
+
+	if (event->parent)
+		event = event->parent;
+
+	rec.header.type	= PERF_RECORD_AUX_OUTPUT_HW_ID;
+	rec.header.misc	= 0;
+	rec.header.size	= sizeof(rec);
+	rec.hw_id	= hw_id;
+
+	perf_event_header__init_id(&rec.header, &sample, event);
+	ret = perf_output_begin(&handle, &sample, event, rec.header.size);
+
+	if (ret)
+		return;
+
+	perf_output_put(&handle, rec);
+	perf_event__output_id_sample(event, &handle, &sample);
+
+	perf_output_end(&handle);
+}
+
+static int
+__perf_event_account_interrupt(struct perf_event *event, int throttle)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	int ret = 0;
+	u64 seq;
+
+	seq = __this_cpu_read(perf_throttled_seq);
+	if (seq != hwc->interrupts_seq) {
+		hwc->interrupts_seq = seq;
+		hwc->interrupts = 1;
+	} else {
+		hwc->interrupts++;
+		if (unlikely(throttle &&
+			     hwc->interrupts > max_samples_per_tick)) {
+			__this_cpu_inc(perf_throttled_count);
+			tick_dep_set_cpu(smp_processor_id(), TICK_DEP_BIT_PERF_EVENTS);
+			hwc->interrupts = MAX_INTERRUPTS;
+			perf_log_throttle(event, 0);
+			ret = 1;
+		}
+	}
+
+	if (event->attr.freq) {
+		u64 now = perf_clock();
+		s64 delta = now - hwc->freq_time_stamp;
+
+		hwc->freq_time_stamp = now;
+
+		if (delta > 0 && delta < 2*TICK_NSEC)
+			perf_adjust_period(event, delta, hwc->last_period, true);
+	}
+
+	return ret;
+}
+
+int perf_event_account_interrupt(struct perf_event *event)
+{
+	return __perf_event_account_interrupt(event, 1);
+}
+
+static inline bool sample_is_allowed(struct perf_event *event, struct pt_regs *regs)
+{
+	/*
+	 * Due to interrupt latency (AKA "skid"), we may enter the
+	 * kernel before taking an overflow, even if the PMU is only
+	 * counting user events.
+	 */
+	if (event->attr.exclude_kernel && !user_mode(regs))
+		return false;
+
+	return true;
+}
+
+/*
+ * Generic event overflow handling, sampling.
+ */
+
+static int __perf_event_overflow(struct perf_event *event,
+				 int throttle, struct perf_sample_data *data,
+				 struct pt_regs *regs)
+{
+	int events = atomic_read(&event->event_limit);
+	int ret = 0;
+
+	/*
+	 * Non-sampling counters might still use the PMI to fold short
+	 * hardware counters, ignore those.
+	 */
+	if (unlikely(!is_sampling_event(event)))
+		return 0;
+
+	ret = __perf_event_account_interrupt(event, throttle);
+
+	/*
+	 * XXX event_limit might not quite work as expected on inherited
+	 * events
+	 */
+
+	event->pending_kill = POLL_IN;
+	if (events && atomic_dec_and_test(&event->event_limit)) {
+		ret = 1;
+		event->pending_kill = POLL_HUP;
+		perf_event_disable_inatomic(event);
+	}
+
+	if (event->attr.sigtrap) {
+		/*
+		 * The desired behaviour of sigtrap vs invalid samples is a bit
+		 * tricky; on the one hand, one should not loose the SIGTRAP if
+		 * it is the first event, on the other hand, we should also not
+		 * trigger the WARN or override the data address.
+		 */
+		bool valid_sample = sample_is_allowed(event, regs);
+		unsigned int pending_id = 1;
+
+		if (regs)
+			pending_id = hash32_ptr((void *)instruction_pointer(regs)) ?: 1;
+		if (!event->pending_sigtrap) {
+			event->pending_sigtrap = pending_id;
+			local_inc(&event->ctx->nr_pending);
+		} else if (event->attr.exclude_kernel && valid_sample) {
+			/*
+			 * Should not be able to return to user space without
+			 * consuming pending_sigtrap; with exceptions:
+			 *
+			 *  1. Where !exclude_kernel, events can overflow again
+			 *     in the kernel without returning to user space.
+			 *
+			 *  2. Events that can overflow again before the IRQ-
+			 *     work without user space progress (e.g. hrtimer).
+			 *     To approximate progress (with false negatives),
+			 *     check 32-bit hash of the current IP.
+			 */
+			WARN_ON_ONCE(event->pending_sigtrap != pending_id);
+		}
+
+		event->pending_addr = 0;
+		if (valid_sample && (data->sample_flags & PERF_SAMPLE_ADDR))
+			event->pending_addr = data->addr;
+		irq_work_queue(&event->pending_irq);
+	}
+
+	READ_ONCE(event->overflow_handler)(event, data, regs);
+
+	if (*perf_event_fasync(event) && event->pending_kill) {
+		event->pending_wakeup = 1;
+		irq_work_queue(&event->pending_irq);
+	}
+
+	return ret;
+}
+
+int perf_event_overflow(struct perf_event *event,
+			struct perf_sample_data *data,
+			struct pt_regs *regs)
+{
+	return __perf_event_overflow(event, 1, data, regs);
+}
+
+/*
+ * Generic software event infrastructure
+ */
+
+struct swevent_htable {
+	struct swevent_hlist		*swevent_hlist;
+	struct mutex			hlist_mutex;
+	int				hlist_refcount;
+
+	/* Recursion avoidance in each contexts */
+	int				recursion[PERF_NR_CONTEXTS];
+};
+
+static DEFINE_PER_CPU(struct swevent_htable, swevent_htable);
+
+/*
+ * We directly increment event->count and keep a second value in
+ * event->hw.period_left to count intervals. This period event
+ * is kept in the range [-sample_period, 0] so that we can use the
+ * sign as trigger.
+ */
+
+u64 perf_swevent_set_period(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	u64 period = hwc->last_period;
+	u64 nr, offset;
+	s64 old, val;
+
+	hwc->last_period = hwc->sample_period;
+
+again:
+	old = val = local64_read(&hwc->period_left);
+	if (val < 0)
+		return 0;
+
+	nr = div64_u64(period + val, period);
+	offset = nr * period;
+	val -= offset;
+	if (local64_cmpxchg(&hwc->period_left, old, val) != old)
+		goto again;
+
+	return nr;
+}
+
+static void perf_swevent_overflow(struct perf_event *event, u64 overflow,
+				    struct perf_sample_data *data,
+				    struct pt_regs *regs)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	int throttle = 0;
+
+	if (!overflow)
+		overflow = perf_swevent_set_period(event);
+
+	if (hwc->interrupts == MAX_INTERRUPTS)
+		return;
+
+	for (; overflow; overflow--) {
+		if (__perf_event_overflow(event, throttle,
+					    data, regs)) {
+			/*
+			 * We inhibit the overflow from happening when
+			 * hwc->interrupts == MAX_INTERRUPTS.
+			 */
+			break;
+		}
+		throttle = 1;
+	}
+}
+
+static void perf_swevent_event(struct perf_event *event, u64 nr,
+			       struct perf_sample_data *data,
+			       struct pt_regs *regs)
+{
+	struct hw_perf_event *hwc = &event->hw;
+
+	local64_add(nr, &event->count);
+
+	if (!regs)
+		return;
+
+	if (!is_sampling_event(event))
+		return;
+
+	if ((event->attr.sample_type & PERF_SAMPLE_PERIOD) && !event->attr.freq) {
+		data->period = nr;
+		return perf_swevent_overflow(event, 1, data, regs);
+	} else
+		data->period = event->hw.last_period;
+
+	if (nr == 1 && hwc->sample_period == 1 && !event->attr.freq)
+		return perf_swevent_overflow(event, 1, data, regs);
+
+	if (local64_add_negative(nr, &hwc->period_left))
+		return;
+
+	perf_swevent_overflow(event, 0, data, regs);
+}
+
+static int perf_exclude_event(struct perf_event *event,
+			      struct pt_regs *regs)
+{
+	if (event->hw.state & PERF_HES_STOPPED)
+		return 1;
+
+	if (regs) {
+		if (event->attr.exclude_user && user_mode(regs))
+			return 1;
+
+		if (event->attr.exclude_kernel && !user_mode(regs))
+			return 1;
+	}
+
+	return 0;
+}
+
+static int perf_swevent_match(struct perf_event *event,
+				enum perf_type_id type,
+				u32 event_id,
+				struct perf_sample_data *data,
+				struct pt_regs *regs)
+{
+	if (event->attr.type != type)
+		return 0;
+
+	if (event->attr.config != event_id)
+		return 0;
+
+	if (perf_exclude_event(event, regs))
+		return 0;
+
+	return 1;
+}
+
+static inline u64 swevent_hash(u64 type, u32 event_id)
+{
+	u64 val = event_id | (type << 32);
+
+	return hash_64(val, SWEVENT_HLIST_BITS);
+}
+
+static inline struct hlist_head *
+__find_swevent_head(struct swevent_hlist *hlist, u64 type, u32 event_id)
+{
+	u64 hash = swevent_hash(type, event_id);
+
+	return &hlist->heads[hash];
+}
+
+/* For the read side: events when they trigger */
+static inline struct hlist_head *
+find_swevent_head_rcu(struct swevent_htable *swhash, u64 type, u32 event_id)
+{
+	struct swevent_hlist *hlist;
+
+	hlist = rcu_dereference(swhash->swevent_hlist);
+	if (!hlist)
+		return NULL;
+
+	return __find_swevent_head(hlist, type, event_id);
+}
+
+/* For the event head insertion and removal in the hlist */
+static inline struct hlist_head *
+find_swevent_head(struct swevent_htable *swhash, struct perf_event *event)
+{
+	struct swevent_hlist *hlist;
+	u32 event_id = event->attr.config;
+	u64 type = event->attr.type;
+
+	/*
+	 * Event scheduling is always serialized against hlist allocation
+	 * and release. Which makes the protected version suitable here.
+	 * The context lock guarantees that.
+	 */
+	hlist = rcu_dereference_protected(swhash->swevent_hlist,
+					  lockdep_is_held(&event->ctx->lock));
+	if (!hlist)
+		return NULL;
+
+	return __find_swevent_head(hlist, type, event_id);
+}
+
+static void do_perf_sw_event(enum perf_type_id type, u32 event_id,
+				    u64 nr,
+				    struct perf_sample_data *data,
+				    struct pt_regs *regs)
+{
+	struct swevent_htable *swhash = this_cpu_ptr(&swevent_htable);
+	struct perf_event *event;
+	struct hlist_head *head;
+
+	rcu_read_lock();
+	head = find_swevent_head_rcu(swhash, type, event_id);
+	if (!head)
+		goto end;
+
+	hlist_for_each_entry_rcu(event, head, hlist_entry) {
+		if (perf_swevent_match(event, type, event_id, data, regs))
+			perf_swevent_event(event, nr, data, regs);
+	}
+end:
+	rcu_read_unlock();
+}
+
+DEFINE_PER_CPU(struct pt_regs, __perf_regs[4]);
+
+int perf_swevent_get_recursion_context(void)
+{
+	struct swevent_htable *swhash = this_cpu_ptr(&swevent_htable);
+
+	return get_recursion_context(swhash->recursion);
+}
+EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context);
+
+void perf_swevent_put_recursion_context(int rctx)
+{
+	struct swevent_htable *swhash = this_cpu_ptr(&swevent_htable);
+
+	put_recursion_context(swhash->recursion, rctx);
+}
+
+void ___perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)
+{
+	struct perf_sample_data data;
+
+	if (WARN_ON_ONCE(!regs))
+		return;
+
+	perf_sample_data_init(&data, addr, 0);
+	do_perf_sw_event(PERF_TYPE_SOFTWARE, event_id, nr, &data, regs);
+}
+
+void __perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)
+{
+	int rctx;
+
+	preempt_disable_notrace();
+	rctx = perf_swevent_get_recursion_context();
+	if (unlikely(rctx < 0))
+		goto fail;
+
+	___perf_sw_event(event_id, nr, regs, addr);
+
+	perf_swevent_put_recursion_context(rctx);
+fail:
+	preempt_enable_notrace();
+}
+
+static void perf_swevent_read(struct perf_event *event)
+{
+}
+
+static int perf_swevent_add(struct perf_event *event, int flags)
+{
+	struct swevent_htable *swhash = this_cpu_ptr(&swevent_htable);
+	struct hw_perf_event *hwc = &event->hw;
+	struct hlist_head *head;
+
+	if (is_sampling_event(event)) {
+		hwc->last_period = hwc->sample_period;
+		perf_swevent_set_period(event);
+	}
+
+	hwc->state = !(flags & PERF_EF_START);
+
+	head = find_swevent_head(swhash, event);
+	if (WARN_ON_ONCE(!head))
+		return -EINVAL;
+
+	hlist_add_head_rcu(&event->hlist_entry, head);
+	perf_event_update_userpage(event);
+
+	return 0;
+}
+
+static void perf_swevent_del(struct perf_event *event, int flags)
+{
+	hlist_del_rcu(&event->hlist_entry);
+}
+
+static void perf_swevent_start(struct perf_event *event, int flags)
+{
+	event->hw.state = 0;
+}
+
+static void perf_swevent_stop(struct perf_event *event, int flags)
+{
+	event->hw.state = PERF_HES_STOPPED;
+}
+
+/* Deref the hlist from the update side */
+static inline struct swevent_hlist *
+swevent_hlist_deref(struct swevent_htable *swhash)
+{
+	return rcu_dereference_protected(swhash->swevent_hlist,
+					 lockdep_is_held(&swhash->hlist_mutex));
+}
+
+static void swevent_hlist_release(struct swevent_htable *swhash)
+{
+	struct swevent_hlist *hlist = swevent_hlist_deref(swhash);
+
+	if (!hlist)
+		return;
+
+	RCU_INIT_POINTER(swhash->swevent_hlist, NULL);
+	kfree_rcu(hlist, rcu_head);
+}
+
+static void swevent_hlist_put_cpu(int cpu)
+{
+	struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
+
+	mutex_lock(&swhash->hlist_mutex);
+
+	if (!--swhash->hlist_refcount)
+		swevent_hlist_release(swhash);
+
+	mutex_unlock(&swhash->hlist_mutex);
+}
+
+static void swevent_hlist_put(void)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		swevent_hlist_put_cpu(cpu);
+}
+
+static int swevent_hlist_get_cpu(int cpu)
+{
+	struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
+	int err = 0;
+
+	mutex_lock(&swhash->hlist_mutex);
+	if (!swevent_hlist_deref(swhash) &&
+	    cpumask_test_cpu(cpu, perf_online_mask)) {
+		struct swevent_hlist *hlist;
+
+		hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
+		if (!hlist) {
+			err = -ENOMEM;
+			goto exit;
+		}
+		rcu_assign_pointer(swhash->swevent_hlist, hlist);
+	}
+	swhash->hlist_refcount++;
+exit:
+	mutex_unlock(&swhash->hlist_mutex);
+
+	return err;
+}
+
+static int swevent_hlist_get(void)
+{
+	int err, cpu, failed_cpu;
+
+	mutex_lock(&pmus_lock);
+	for_each_possible_cpu(cpu) {
+		err = swevent_hlist_get_cpu(cpu);
+		if (err) {
+			failed_cpu = cpu;
+			goto fail;
+		}
+	}
+	mutex_unlock(&pmus_lock);
+	return 0;
+fail:
+	for_each_possible_cpu(cpu) {
+		if (cpu == failed_cpu)
+			break;
+		swevent_hlist_put_cpu(cpu);
+	}
+	mutex_unlock(&pmus_lock);
+	return err;
+}
+
+struct static_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
+
+static void sw_perf_event_destroy(struct perf_event *event)
+{
+	u64 event_id = event->attr.config;
+
+	WARN_ON(event->parent);
+
+	static_key_slow_dec(&perf_swevent_enabled[event_id]);
+	swevent_hlist_put();
+}
+
+static int perf_swevent_init(struct perf_event *event)
+{
+	u64 event_id = event->attr.config;
+
+	if (event->attr.type != PERF_TYPE_SOFTWARE)
+		return -ENOENT;
+
+	/*
+	 * no branch sampling for software events
+	 */
+	if (has_branch_stack(event))
+		return -EOPNOTSUPP;
+
+	switch (event_id) {
+	case PERF_COUNT_SW_CPU_CLOCK:
+	case PERF_COUNT_SW_TASK_CLOCK:
+		return -ENOENT;
+
+	default:
+		break;
+	}
+
+	if (event_id >= PERF_COUNT_SW_MAX)
+		return -ENOENT;
+
+	if (!event->parent) {
+		int err;
+
+		err = swevent_hlist_get();
+		if (err)
+			return err;
+
+		static_key_slow_inc(&perf_swevent_enabled[event_id]);
+		event->destroy = sw_perf_event_destroy;
+	}
+
+	return 0;
+}
+
+static struct pmu perf_swevent = {
+	.task_ctx_nr	= perf_sw_context,
+
+	.capabilities	= PERF_PMU_CAP_NO_NMI,
+
+	.event_init	= perf_swevent_init,
+	.add		= perf_swevent_add,
+	.del		= perf_swevent_del,
+	.start		= perf_swevent_start,
+	.stop		= perf_swevent_stop,
+	.read		= perf_swevent_read,
+};
+
+#ifdef CONFIG_EVENT_TRACING
+
+static int perf_tp_filter_match(struct perf_event *event,
+				struct perf_sample_data *data)
+{
+	void *record = data->raw->frag.data;
+
+	/* only top level events have filters set */
+	if (event->parent)
+		event = event->parent;
+
+	if (likely(!event->filter) || filter_match_preds(event->filter, record))
+		return 1;
+	return 0;
+}
+
+static int perf_tp_event_match(struct perf_event *event,
+				struct perf_sample_data *data,
+				struct pt_regs *regs)
+{
+	if (event->hw.state & PERF_HES_STOPPED)
+		return 0;
+	/*
+	 * If exclude_kernel, only trace user-space tracepoints (uprobes)
+	 */
+	if (event->attr.exclude_kernel && !user_mode(regs))
+		return 0;
+
+	if (!perf_tp_filter_match(event, data))
+		return 0;
+
+	return 1;
+}
+
+void perf_trace_run_bpf_submit(void *raw_data, int size, int rctx,
+			       struct trace_event_call *call, u64 count,
+			       struct pt_regs *regs, struct hlist_head *head,
+			       struct task_struct *task)
+{
+	if (bpf_prog_array_valid(call)) {
+		*(struct pt_regs **)raw_data = regs;
+		if (!trace_call_bpf(call, raw_data) || hlist_empty(head)) {
+			perf_swevent_put_recursion_context(rctx);
+			return;
+		}
+	}
+	perf_tp_event(call->event.type, count, raw_data, size, regs, head,
+		      rctx, task);
+}
+EXPORT_SYMBOL_GPL(perf_trace_run_bpf_submit);
+
+void perf_tp_event(u16 event_type, u64 count, void *record, int entry_size,
+		   struct pt_regs *regs, struct hlist_head *head, int rctx,
+		   struct task_struct *task)
+{
+	struct perf_sample_data data;
+	struct perf_event *event;
+
+	struct perf_raw_record raw = {
+		.frag = {
+			.size = entry_size,
+			.data = record,
+		},
+	};
+
+	perf_sample_data_init(&data, 0, 0);
+	data.raw = &raw;
+	data.sample_flags |= PERF_SAMPLE_RAW;
+
+	perf_trace_buf_update(record, event_type);
+
+	hlist_for_each_entry_rcu(event, head, hlist_entry) {
+		if (perf_tp_event_match(event, &data, regs))
+			perf_swevent_event(event, count, &data, regs);
+	}
+
+	/*
+	 * If we got specified a target task, also iterate its context and
+	 * deliver this event there too.
+	 */
+	if (task && task != current) {
+		struct perf_event_context *ctx;
+		struct trace_entry *entry = record;
+
+		rcu_read_lock();
+		ctx = rcu_dereference(task->perf_event_ctxp[perf_sw_context]);
+		if (!ctx)
+			goto unlock;
+
+		list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
+			if (event->cpu != smp_processor_id())
+				continue;
+			if (event->attr.type != PERF_TYPE_TRACEPOINT)
+				continue;
+			if (event->attr.config != entry->type)
+				continue;
+			/* Cannot deliver synchronous signal to other task. */
+			if (event->attr.sigtrap)
+				continue;
+			if (perf_tp_event_match(event, &data, regs))
+				perf_swevent_event(event, count, &data, regs);
+		}
+unlock:
+		rcu_read_unlock();
+	}
+
+	perf_swevent_put_recursion_context(rctx);
+}
+EXPORT_SYMBOL_GPL(perf_tp_event);
+
+static void tp_perf_event_destroy(struct perf_event *event)
+{
+	perf_trace_destroy(event);
+}
+
+static int perf_tp_event_init(struct perf_event *event)
+{
+	int err;
+
+	if (event->attr.type != PERF_TYPE_TRACEPOINT)
+		return -ENOENT;
+
+	/*
+	 * no branch sampling for tracepoint events
+	 */
+	if (has_branch_stack(event))
+		return -EOPNOTSUPP;
+
+	err = perf_trace_init(event);
+	if (err)
+		return err;
+
+	event->destroy = tp_perf_event_destroy;
+
+	return 0;
+}
+
+static struct pmu perf_tracepoint = {
+	.task_ctx_nr	= perf_sw_context,
+
+	.event_init	= perf_tp_event_init,
+	.add		= perf_trace_add,
+	.del		= perf_trace_del,
+	.start		= perf_swevent_start,
+	.stop		= perf_swevent_stop,
+	.read		= perf_swevent_read,
+};
+
+#if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS)
+/*
+ * Flags in config, used by dynamic PMU kprobe and uprobe
+ * The flags should match following PMU_FORMAT_ATTR().
+ *
+ * PERF_PROBE_CONFIG_IS_RETPROBE if set, create kretprobe/uretprobe
+ *                               if not set, create kprobe/uprobe
+ *
+ * The following values specify a reference counter (or semaphore in the
+ * terminology of tools like dtrace, systemtap, etc.) Userspace Statically
+ * Defined Tracepoints (USDT). Currently, we use 40 bit for the offset.
+ *
+ * PERF_UPROBE_REF_CTR_OFFSET_BITS	# of bits in config as th offset
+ * PERF_UPROBE_REF_CTR_OFFSET_SHIFT	# of bits to shift left
+ */
+enum perf_probe_config {
+	PERF_PROBE_CONFIG_IS_RETPROBE = 1U << 0,  /* [k,u]retprobe */
+	PERF_UPROBE_REF_CTR_OFFSET_BITS = 32,
+	PERF_UPROBE_REF_CTR_OFFSET_SHIFT = 64 - PERF_UPROBE_REF_CTR_OFFSET_BITS,
+};
+
+PMU_FORMAT_ATTR(retprobe, "config:0");
+#endif
+
+#ifdef CONFIG_KPROBE_EVENTS
+static struct attribute *kprobe_attrs[] = {
+	&format_attr_retprobe.attr,
+	NULL,
+};
+
+static struct attribute_group kprobe_format_group = {
+	.name = "format",
+	.attrs = kprobe_attrs,
+};
+
+static const struct attribute_group *kprobe_attr_groups[] = {
+	&kprobe_format_group,
+	NULL,
+};
+
+static int perf_kprobe_event_init(struct perf_event *event);
+static struct pmu perf_kprobe = {
+	.task_ctx_nr	= perf_sw_context,
+	.event_init	= perf_kprobe_event_init,
+	.add		= perf_trace_add,
+	.del		= perf_trace_del,
+	.start		= perf_swevent_start,
+	.stop		= perf_swevent_stop,
+	.read		= perf_swevent_read,
+	.attr_groups	= kprobe_attr_groups,
+};
+
+static int perf_kprobe_event_init(struct perf_event *event)
+{
+	int err;
+	bool is_retprobe;
+
+	if (event->attr.type != perf_kprobe.type)
+		return -ENOENT;
+
+	if (!perfmon_capable())
+		return -EACCES;
+
+	/*
+	 * no branch sampling for probe events
+	 */
+	if (has_branch_stack(event))
+		return -EOPNOTSUPP;
+
+	is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
+	err = perf_kprobe_init(event, is_retprobe);
+	if (err)
+		return err;
+
+	event->destroy = perf_kprobe_destroy;
+
+	return 0;
+}
+#endif /* CONFIG_KPROBE_EVENTS */
+
+#ifdef CONFIG_UPROBE_EVENTS
+PMU_FORMAT_ATTR(ref_ctr_offset, "config:32-63");
+
+static struct attribute *uprobe_attrs[] = {
+	&format_attr_retprobe.attr,
+	&format_attr_ref_ctr_offset.attr,
+	NULL,
+};
+
+static struct attribute_group uprobe_format_group = {
+	.name = "format",
+	.attrs = uprobe_attrs,
+};
+
+static const struct attribute_group *uprobe_attr_groups[] = {
+	&uprobe_format_group,
+	NULL,
+};
+
+static int perf_uprobe_event_init(struct perf_event *event);
+static struct pmu perf_uprobe = {
+	.task_ctx_nr	= perf_sw_context,
+	.event_init	= perf_uprobe_event_init,
+	.add		= perf_trace_add,
+	.del		= perf_trace_del,
+	.start		= perf_swevent_start,
+	.stop		= perf_swevent_stop,
+	.read		= perf_swevent_read,
+	.attr_groups	= uprobe_attr_groups,
+};
+
+static int perf_uprobe_event_init(struct perf_event *event)
+{
+	int err;
+	unsigned long ref_ctr_offset;
+	bool is_retprobe;
+
+	if (event->attr.type != perf_uprobe.type)
+		return -ENOENT;
+
+	if (!perfmon_capable())
+		return -EACCES;
+
+	/*
+	 * no branch sampling for probe events
+	 */
+	if (has_branch_stack(event))
+		return -EOPNOTSUPP;
+
+	is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
+	ref_ctr_offset = event->attr.config >> PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
+	err = perf_uprobe_init(event, ref_ctr_offset, is_retprobe);
+	if (err)
+		return err;
+
+	event->destroy = perf_uprobe_destroy;
+
+	return 0;
+}
+#endif /* CONFIG_UPROBE_EVENTS */
+
+static inline void perf_tp_register(void)
+{
+	perf_pmu_register(&perf_tracepoint, "tracepoint", PERF_TYPE_TRACEPOINT);
+#ifdef CONFIG_KPROBE_EVENTS
+	perf_pmu_register(&perf_kprobe, "kprobe", -1);
+#endif
+#ifdef CONFIG_UPROBE_EVENTS
+	perf_pmu_register(&perf_uprobe, "uprobe", -1);
+#endif
+}
+
+static void perf_event_free_filter(struct perf_event *event)
+{
+	ftrace_profile_free_filter(event);
+}
+
+#ifdef CONFIG_BPF_SYSCALL
+static void bpf_overflow_handler(struct perf_event *event,
+				 struct perf_sample_data *data,
+				 struct pt_regs *regs)
+{
+	struct bpf_perf_event_data_kern ctx = {
+		.data = data,
+		.event = event,
+	};
+	struct bpf_prog *prog;
+	int ret = 0;
+
+	ctx.regs = perf_arch_bpf_user_pt_regs(regs);
+	if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1))
+		goto out;
+	rcu_read_lock();
+	prog = READ_ONCE(event->prog);
+	if (prog) {
+		if (prog->call_get_stack &&
+		    (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) &&
+		    !(data->sample_flags & PERF_SAMPLE_CALLCHAIN)) {
+			data->callchain = perf_callchain(event, regs);
+			data->sample_flags |= PERF_SAMPLE_CALLCHAIN;
+		}
+
+		ret = bpf_prog_run(prog, &ctx);
+	}
+	rcu_read_unlock();
+out:
+	__this_cpu_dec(bpf_prog_active);
+	if (!ret)
+		return;
+
+	event->orig_overflow_handler(event, data, regs);
+}
+
+static int perf_event_set_bpf_handler(struct perf_event *event,
+				      struct bpf_prog *prog,
+				      u64 bpf_cookie)
+{
+	if (event->overflow_handler_context)
+		/* hw breakpoint or kernel counter */
+		return -EINVAL;
+
+	if (event->prog)
+		return -EEXIST;
+
+	if (prog->type != BPF_PROG_TYPE_PERF_EVENT)
+		return -EINVAL;
+
+	if (event->attr.precise_ip &&
+	    prog->call_get_stack &&
+	    (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) ||
+	     event->attr.exclude_callchain_kernel ||
+	     event->attr.exclude_callchain_user)) {
+		/*
+		 * On perf_event with precise_ip, calling bpf_get_stack()
+		 * may trigger unwinder warnings and occasional crashes.
+		 * bpf_get_[stack|stackid] works around this issue by using
+		 * callchain attached to perf_sample_data. If the
+		 * perf_event does not full (kernel and user) callchain
+		 * attached to perf_sample_data, do not allow attaching BPF
+		 * program that calls bpf_get_[stack|stackid].
+		 */
+		return -EPROTO;
+	}
+
+	event->prog = prog;
+	event->bpf_cookie = bpf_cookie;
+	event->orig_overflow_handler = READ_ONCE(event->overflow_handler);
+	WRITE_ONCE(event->overflow_handler, bpf_overflow_handler);
+	return 0;
+}
+
+static void perf_event_free_bpf_handler(struct perf_event *event)
+{
+	struct bpf_prog *prog = event->prog;
+
+	if (!prog)
+		return;
+
+	WRITE_ONCE(event->overflow_handler, event->orig_overflow_handler);
+	event->prog = NULL;
+	bpf_prog_put(prog);
+}
+#else
+static int perf_event_set_bpf_handler(struct perf_event *event,
+				      struct bpf_prog *prog,
+				      u64 bpf_cookie)
+{
+	return -EOPNOTSUPP;
+}
+static void perf_event_free_bpf_handler(struct perf_event *event)
+{
+}
+#endif
+
+/*
+ * returns true if the event is a tracepoint, or a kprobe/upprobe created
+ * with perf_event_open()
+ */
+static inline bool perf_event_is_tracing(struct perf_event *event)
+{
+	if (event->pmu == &perf_tracepoint)
+		return true;
+#ifdef CONFIG_KPROBE_EVENTS
+	if (event->pmu == &perf_kprobe)
+		return true;
+#endif
+#ifdef CONFIG_UPROBE_EVENTS
+	if (event->pmu == &perf_uprobe)
+		return true;
+#endif
+	return false;
+}
+
+int perf_event_set_bpf_prog(struct perf_event *event, struct bpf_prog *prog,
+			    u64 bpf_cookie)
+{
+	bool is_kprobe, is_uprobe, is_tracepoint, is_syscall_tp;
+
+	if (!perf_event_is_tracing(event))
+		return perf_event_set_bpf_handler(event, prog, bpf_cookie);
+
+	is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_KPROBE;
+	is_uprobe = event->tp_event->flags & TRACE_EVENT_FL_UPROBE;
+	is_tracepoint = event->tp_event->flags & TRACE_EVENT_FL_TRACEPOINT;
+	is_syscall_tp = is_syscall_trace_event(event->tp_event);
+	if (!is_kprobe && !is_uprobe && !is_tracepoint && !is_syscall_tp)
+		/* bpf programs can only be attached to u/kprobe or tracepoint */
+		return -EINVAL;
+
+	if (((is_kprobe || is_uprobe) && prog->type != BPF_PROG_TYPE_KPROBE) ||
+	    (is_tracepoint && prog->type != BPF_PROG_TYPE_TRACEPOINT) ||
+	    (is_syscall_tp && prog->type != BPF_PROG_TYPE_TRACEPOINT))
+		return -EINVAL;
+
+	if (prog->type == BPF_PROG_TYPE_KPROBE && prog->aux->sleepable && !is_uprobe)
+		/* only uprobe programs are allowed to be sleepable */
+		return -EINVAL;
+
+	/* Kprobe override only works for kprobes, not uprobes. */
+	if (prog->kprobe_override && !is_kprobe)
+		return -EINVAL;
+
+	if (is_tracepoint || is_syscall_tp) {
+		int off = trace_event_get_offsets(event->tp_event);
+
+		if (prog->aux->max_ctx_offset > off)
+			return -EACCES;
+	}
+
+	return perf_event_attach_bpf_prog(event, prog, bpf_cookie);
+}
+
+void perf_event_free_bpf_prog(struct perf_event *event)
+{
+	if (!perf_event_is_tracing(event)) {
+		perf_event_free_bpf_handler(event);
+		return;
+	}
+	perf_event_detach_bpf_prog(event);
+}
+
+#else
+
+static inline void perf_tp_register(void)
+{
+}
+
+static void perf_event_free_filter(struct perf_event *event)
+{
+}
+
+int perf_event_set_bpf_prog(struct perf_event *event, struct bpf_prog *prog,
+			    u64 bpf_cookie)
+{
+	return -ENOENT;
+}
+
+void perf_event_free_bpf_prog(struct perf_event *event)
+{
+}
+#endif /* CONFIG_EVENT_TRACING */
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+void perf_bp_event(struct perf_event *bp, void *data)
+{
+	struct perf_sample_data sample;
+	struct pt_regs *regs = data;
+
+	perf_sample_data_init(&sample, bp->attr.bp_addr, 0);
+
+	if (!bp->hw.state && !perf_exclude_event(bp, regs))
+		perf_swevent_event(bp, 1, &sample, regs);
+}
+#endif
+
+/*
+ * Allocate a new address filter
+ */
+static struct perf_addr_filter *
+perf_addr_filter_new(struct perf_event *event, struct list_head *filters)
+{
+	int node = cpu_to_node(event->cpu == -1 ? 0 : event->cpu);
+	struct perf_addr_filter *filter;
+
+	filter = kzalloc_node(sizeof(*filter), GFP_KERNEL, node);
+	if (!filter)
+		return NULL;
+
+	INIT_LIST_HEAD(&filter->entry);
+	list_add_tail(&filter->entry, filters);
+
+	return filter;
+}
+
+static void free_filters_list(struct list_head *filters)
+{
+	struct perf_addr_filter *filter, *iter;
+
+	list_for_each_entry_safe(filter, iter, filters, entry) {
+		path_put(&filter->path);
+		list_del(&filter->entry);
+		kfree(filter);
+	}
+}
+
+/*
+ * Free existing address filters and optionally install new ones
+ */
+static void perf_addr_filters_splice(struct perf_event *event,
+				     struct list_head *head)
+{
+	unsigned long flags;
+	LIST_HEAD(list);
+
+	if (!has_addr_filter(event))
+		return;
+
+	/* don't bother with children, they don't have their own filters */
+	if (event->parent)
+		return;
+
+	raw_spin_lock_irqsave(&event->addr_filters.lock, flags);
+
+	list_splice_init(&event->addr_filters.list, &list);
+	if (head)
+		list_splice(head, &event->addr_filters.list);
+
+	raw_spin_unlock_irqrestore(&event->addr_filters.lock, flags);
+
+	free_filters_list(&list);
+}
+
+/*
+ * Scan through mm's vmas and see if one of them matches the
+ * @filter; if so, adjust filter's address range.
+ * Called with mm::mmap_lock down for reading.
+ */
+static void perf_addr_filter_apply(struct perf_addr_filter *filter,
+				   struct mm_struct *mm,
+				   struct perf_addr_filter_range *fr)
+{
+	struct vm_area_struct *vma;
+	VMA_ITERATOR(vmi, mm, 0);
+
+	for_each_vma(vmi, vma) {
+		if (!vma->vm_file)
+			continue;
+
+		if (perf_addr_filter_vma_adjust(filter, vma, fr))
+			return;
+	}
+}
+
+/*
+ * Update event's address range filters based on the
+ * task's existing mappings, if any.
+ */
+static void perf_event_addr_filters_apply(struct perf_event *event)
+{
+	struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
+	struct task_struct *task = READ_ONCE(event->ctx->task);
+	struct perf_addr_filter *filter;
+	struct mm_struct *mm = NULL;
+	unsigned int count = 0;
+	unsigned long flags;
+
+	/*
+	 * We may observe TASK_TOMBSTONE, which means that the event tear-down
+	 * will stop on the parent's child_mutex that our caller is also holding
+	 */
+	if (task == TASK_TOMBSTONE)
+		return;
+
+	if (ifh->nr_file_filters) {
+		mm = get_task_mm(task);
+		if (!mm)
+			goto restart;
+
+		mmap_read_lock(mm);
+	}
+
+	raw_spin_lock_irqsave(&ifh->lock, flags);
+	list_for_each_entry(filter, &ifh->list, entry) {
+		if (filter->path.dentry) {
+			/*
+			 * Adjust base offset if the filter is associated to a
+			 * binary that needs to be mapped:
+			 */
+			event->addr_filter_ranges[count].start = 0;
+			event->addr_filter_ranges[count].size = 0;
+
+			perf_addr_filter_apply(filter, mm, &event->addr_filter_ranges[count]);
+		} else {
+			event->addr_filter_ranges[count].start = filter->offset;
+			event->addr_filter_ranges[count].size  = filter->size;
+		}
+
+		count++;
+	}
+
+	event->addr_filters_gen++;
+	raw_spin_unlock_irqrestore(&ifh->lock, flags);
+
+	if (ifh->nr_file_filters) {
+		mmap_read_unlock(mm);
+
+		mmput(mm);
+	}
+
+restart:
+	perf_event_stop(event, 1);
+}
+
+/*
+ * Address range filtering: limiting the data to certain
+ * instruction address ranges. Filters are ioctl()ed to us from
+ * userspace as ascii strings.
+ *
+ * Filter string format:
+ *
+ * ACTION RANGE_SPEC
+ * where ACTION is one of the
+ *  * "filter": limit the trace to this region
+ *  * "start": start tracing from this address
+ *  * "stop": stop tracing at this address/region;
+ * RANGE_SPEC is
+ *  * for kernel addresses: <start address>[/<size>]
+ *  * for object files:     <start address>[/<size>]@</path/to/object/file>
+ *
+ * if <size> is not specified or is zero, the range is treated as a single
+ * address; not valid for ACTION=="filter".
+ */
+enum {
+	IF_ACT_NONE = -1,
+	IF_ACT_FILTER,
+	IF_ACT_START,
+	IF_ACT_STOP,
+	IF_SRC_FILE,
+	IF_SRC_KERNEL,
+	IF_SRC_FILEADDR,
+	IF_SRC_KERNELADDR,
+};
+
+enum {
+	IF_STATE_ACTION = 0,
+	IF_STATE_SOURCE,
+	IF_STATE_END,
+};
+
+static const match_table_t if_tokens = {
+	{ IF_ACT_FILTER,	"filter" },
+	{ IF_ACT_START,		"start" },
+	{ IF_ACT_STOP,		"stop" },
+	{ IF_SRC_FILE,		"%u/%u@%s" },
+	{ IF_SRC_KERNEL,	"%u/%u" },
+	{ IF_SRC_FILEADDR,	"%u@%s" },
+	{ IF_SRC_KERNELADDR,	"%u" },
+	{ IF_ACT_NONE,		NULL },
+};
+
+/*
+ * Address filter string parser
+ */
+static int
+perf_event_parse_addr_filter(struct perf_event *event, char *fstr,
+			     struct list_head *filters)
+{
+	struct perf_addr_filter *filter = NULL;
+	char *start, *orig, *filename = NULL;
+	substring_t args[MAX_OPT_ARGS];
+	int state = IF_STATE_ACTION, token;
+	unsigned int kernel = 0;
+	int ret = -EINVAL;
+
+	orig = fstr = kstrdup(fstr, GFP_KERNEL);
+	if (!fstr)
+		return -ENOMEM;
+
+	while ((start = strsep(&fstr, " ,\n")) != NULL) {
+		static const enum perf_addr_filter_action_t actions[] = {
+			[IF_ACT_FILTER]	= PERF_ADDR_FILTER_ACTION_FILTER,
+			[IF_ACT_START]	= PERF_ADDR_FILTER_ACTION_START,
+			[IF_ACT_STOP]	= PERF_ADDR_FILTER_ACTION_STOP,
+		};
+		ret = -EINVAL;
+
+		if (!*start)
+			continue;
+
+		/* filter definition begins */
+		if (state == IF_STATE_ACTION) {
+			filter = perf_addr_filter_new(event, filters);
+			if (!filter)
+				goto fail;
+		}
+
+		token = match_token(start, if_tokens, args);
+		switch (token) {
+		case IF_ACT_FILTER:
+		case IF_ACT_START:
+		case IF_ACT_STOP:
+			if (state != IF_STATE_ACTION)
+				goto fail;
+
+			filter->action = actions[token];
+			state = IF_STATE_SOURCE;
+			break;
+
+		case IF_SRC_KERNELADDR:
+		case IF_SRC_KERNEL:
+			kernel = 1;
+			fallthrough;
+
+		case IF_SRC_FILEADDR:
+		case IF_SRC_FILE:
+			if (state != IF_STATE_SOURCE)
+				goto fail;
+
+			*args[0].to = 0;
+			ret = kstrtoul(args[0].from, 0, &filter->offset);
+			if (ret)
+				goto fail;
+
+			if (token == IF_SRC_KERNEL || token == IF_SRC_FILE) {
+				*args[1].to = 0;
+				ret = kstrtoul(args[1].from, 0, &filter->size);
+				if (ret)
+					goto fail;
+			}
+
+			if (token == IF_SRC_FILE || token == IF_SRC_FILEADDR) {
+				int fpos = token == IF_SRC_FILE ? 2 : 1;
+
+				kfree(filename);
+				filename = match_strdup(&args[fpos]);
+				if (!filename) {
+					ret = -ENOMEM;
+					goto fail;
+				}
+			}
+
+			state = IF_STATE_END;
+			break;
+
+		default:
+			goto fail;
+		}
+
+		/*
+		 * Filter definition is fully parsed, validate and install it.
+		 * Make sure that it doesn't contradict itself or the event's
+		 * attribute.
+		 */
+		if (state == IF_STATE_END) {
+			ret = -EINVAL;
+
+			/*
+			 * ACTION "filter" must have a non-zero length region
+			 * specified.
+			 */
+			if (filter->action == PERF_ADDR_FILTER_ACTION_FILTER &&
+			    !filter->size)
+				goto fail;
+
+			if (!kernel) {
+				if (!filename)
+					goto fail;
+
+				/*
+				 * For now, we only support file-based filters
+				 * in per-task events; doing so for CPU-wide
+				 * events requires additional context switching
+				 * trickery, since same object code will be
+				 * mapped at different virtual addresses in
+				 * different processes.
+				 */
+				ret = -EOPNOTSUPP;
+				if (!event->ctx->task)
+					goto fail;
+
+				/* look up the path and grab its inode */
+				ret = kern_path(filename, LOOKUP_FOLLOW,
+						&filter->path);
+				if (ret)
+					goto fail;
+
+				ret = -EINVAL;
+				if (!filter->path.dentry ||
+				    !S_ISREG(d_inode(filter->path.dentry)
+					     ->i_mode))
+					goto fail;
+
+				event->addr_filters.nr_file_filters++;
+			}
+
+			/* ready to consume more filters */
+			kfree(filename);
+			filename = NULL;
+			state = IF_STATE_ACTION;
+			filter = NULL;
+			kernel = 0;
+		}
+	}
+
+	if (state != IF_STATE_ACTION)
+		goto fail;
+
+	kfree(filename);
+	kfree(orig);
+
+	return 0;
+
+fail:
+	kfree(filename);
+	free_filters_list(filters);
+	kfree(orig);
+
+	return ret;
+}
+
+static int
+perf_event_set_addr_filter(struct perf_event *event, char *filter_str)
+{
+	LIST_HEAD(filters);
+	int ret;
+
+	/*
+	 * Since this is called in perf_ioctl() path, we're already holding
+	 * ctx::mutex.
+	 */
+	lockdep_assert_held(&event->ctx->mutex);
+
+	if (WARN_ON_ONCE(event->parent))
+		return -EINVAL;
+
+	ret = perf_event_parse_addr_filter(event, filter_str, &filters);
+	if (ret)
+		goto fail_clear_files;
+
+	ret = event->pmu->addr_filters_validate(&filters);
+	if (ret)
+		goto fail_free_filters;
+
+	/* remove existing filters, if any */
+	perf_addr_filters_splice(event, &filters);
+
+	/* install new filters */
+	perf_event_for_each_child(event, perf_event_addr_filters_apply);
+
+	return ret;
+
+fail_free_filters:
+	free_filters_list(&filters);
+
+fail_clear_files:
+	event->addr_filters.nr_file_filters = 0;
+
+	return ret;
+}
+
+static int perf_event_set_filter(struct perf_event *event, void __user *arg)
+{
+	int ret = -EINVAL;
+	char *filter_str;
+
+	filter_str = strndup_user(arg, PAGE_SIZE);
+	if (IS_ERR(filter_str))
+		return PTR_ERR(filter_str);
+
+#ifdef CONFIG_EVENT_TRACING
+	if (perf_event_is_tracing(event)) {
+		struct perf_event_context *ctx = event->ctx;
+
+		/*
+		 * Beware, here be dragons!!
+		 *
+		 * the tracepoint muck will deadlock against ctx->mutex, but
+		 * the tracepoint stuff does not actually need it. So
+		 * temporarily drop ctx->mutex. As per perf_event_ctx_lock() we
+		 * already have a reference on ctx.
+		 *
+		 * This can result in event getting moved to a different ctx,
+		 * but that does not affect the tracepoint state.
+		 */
+		mutex_unlock(&ctx->mutex);
+		ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
+		mutex_lock(&ctx->mutex);
+	} else
+#endif
+	if (has_addr_filter(event))
+		ret = perf_event_set_addr_filter(event, filter_str);
+
+	kfree(filter_str);
+	return ret;
+}
+
+/*
+ * hrtimer based swevent callback
+ */
+
+static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer)
+{
+	enum hrtimer_restart ret = HRTIMER_RESTART;
+	struct perf_sample_data data;
+	struct pt_regs *regs;
+	struct perf_event *event;
+	u64 period;
+
+	event = container_of(hrtimer, struct perf_event, hw.hrtimer);
+
+	if (event->state != PERF_EVENT_STATE_ACTIVE)
+		return HRTIMER_NORESTART;
+
+	event->pmu->read(event);
+
+	perf_sample_data_init(&data, 0, event->hw.last_period);
+	regs = get_irq_regs();
+
+	if (regs && !perf_exclude_event(event, regs)) {
+		if (!(event->attr.exclude_idle && is_idle_task(current)))
+			if (__perf_event_overflow(event, 1, &data, regs))
+				ret = HRTIMER_NORESTART;
+	}
+
+	period = max_t(u64, 10000, event->hw.sample_period);
+	hrtimer_forward_now(hrtimer, ns_to_ktime(period));
+
+	return ret;
+}
+
+static void perf_swevent_start_hrtimer(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	s64 period;
+
+	if (!is_sampling_event(event))
+		return;
+
+	period = local64_read(&hwc->period_left);
+	if (period) {
+		if (period < 0)
+			period = 10000;
+
+		local64_set(&hwc->period_left, 0);
+	} else {
+		period = max_t(u64, 10000, hwc->sample_period);
+	}
+	hrtimer_start(&hwc->hrtimer, ns_to_ktime(period),
+		      HRTIMER_MODE_REL_PINNED_HARD);
+}
+
+static void perf_swevent_cancel_hrtimer(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+
+	if (is_sampling_event(event)) {
+		ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer);
+		local64_set(&hwc->period_left, ktime_to_ns(remaining));
+
+		hrtimer_cancel(&hwc->hrtimer);
+	}
+}
+
+static void perf_swevent_init_hrtimer(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+
+	if (!is_sampling_event(event))
+		return;
+
+	hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
+	hwc->hrtimer.function = perf_swevent_hrtimer;
+
+	/*
+	 * Since hrtimers have a fixed rate, we can do a static freq->period
+	 * mapping and avoid the whole period adjust feedback stuff.
+	 */
+	if (event->attr.freq) {
+		long freq = event->attr.sample_freq;
+
+		event->attr.sample_period = NSEC_PER_SEC / freq;
+		hwc->sample_period = event->attr.sample_period;
+		local64_set(&hwc->period_left, hwc->sample_period);
+		hwc->last_period = hwc->sample_period;
+		event->attr.freq = 0;
+	}
+}
+
+/*
+ * Software event: cpu wall time clock
+ */
+
+static void cpu_clock_event_update(struct perf_event *event)
+{
+	s64 prev;
+	u64 now;
+
+	now = local_clock();
+	prev = local64_xchg(&event->hw.prev_count, now);
+	local64_add(now - prev, &event->count);
+}
+
+static void cpu_clock_event_start(struct perf_event *event, int flags)
+{
+	local64_set(&event->hw.prev_count, local_clock());
+	perf_swevent_start_hrtimer(event);
+}
+
+static void cpu_clock_event_stop(struct perf_event *event, int flags)
+{
+	perf_swevent_cancel_hrtimer(event);
+	cpu_clock_event_update(event);
+}
+
+static int cpu_clock_event_add(struct perf_event *event, int flags)
+{
+	if (flags & PERF_EF_START)
+		cpu_clock_event_start(event, flags);
+	perf_event_update_userpage(event);
+
+	return 0;
+}
+
+static void cpu_clock_event_del(struct perf_event *event, int flags)
+{
+	cpu_clock_event_stop(event, flags);
+}
+
+static void cpu_clock_event_read(struct perf_event *event)
+{
+	cpu_clock_event_update(event);
+}
+
+static int cpu_clock_event_init(struct perf_event *event)
+{
+	if (event->attr.type != PERF_TYPE_SOFTWARE)
+		return -ENOENT;
+
+	if (event->attr.config != PERF_COUNT_SW_CPU_CLOCK)
+		return -ENOENT;
+
+	/*
+	 * no branch sampling for software events
+	 */
+	if (has_branch_stack(event))
+		return -EOPNOTSUPP;
+
+	perf_swevent_init_hrtimer(event);
+
+	return 0;
+}
+
+static struct pmu perf_cpu_clock = {
+	.task_ctx_nr	= perf_sw_context,
+
+	.capabilities	= PERF_PMU_CAP_NO_NMI,
+
+	.event_init	= cpu_clock_event_init,
+	.add		= cpu_clock_event_add,
+	.del		= cpu_clock_event_del,
+	.start		= cpu_clock_event_start,
+	.stop		= cpu_clock_event_stop,
+	.read		= cpu_clock_event_read,
+};
+
+/*
+ * Software event: task time clock
+ */
+
+static void task_clock_event_update(struct perf_event *event, u64 now)
+{
+	u64 prev;
+	s64 delta;
+
+	prev = local64_xchg(&event->hw.prev_count, now);
+	delta = now - prev;
+	local64_add(delta, &event->count);
+}
+
+static void task_clock_event_start(struct perf_event *event, int flags)
+{
+	local64_set(&event->hw.prev_count, event->ctx->time);
+	perf_swevent_start_hrtimer(event);
+}
+
+static void task_clock_event_stop(struct perf_event *event, int flags)
+{
+	perf_swevent_cancel_hrtimer(event);
+	task_clock_event_update(event, event->ctx->time);
+}
+
+static int task_clock_event_add(struct perf_event *event, int flags)
+{
+	if (flags & PERF_EF_START)
+		task_clock_event_start(event, flags);
+	perf_event_update_userpage(event);
+
+	return 0;
+}
+
+static void task_clock_event_del(struct perf_event *event, int flags)
+{
+	task_clock_event_stop(event, PERF_EF_UPDATE);
+}
+
+static void task_clock_event_read(struct perf_event *event)
+{
+	u64 now = perf_clock();
+	u64 delta = now - event->ctx->timestamp;
+	u64 time = event->ctx->time + delta;
+
+	task_clock_event_update(event, time);
+}
+
+static int task_clock_event_init(struct perf_event *event)
+{
+	if (event->attr.type != PERF_TYPE_SOFTWARE)
+		return -ENOENT;
+
+	if (event->attr.config != PERF_COUNT_SW_TASK_CLOCK)
+		return -ENOENT;
+
+	/*
+	 * no branch sampling for software events
+	 */
+	if (has_branch_stack(event))
+		return -EOPNOTSUPP;
+
+	perf_swevent_init_hrtimer(event);
+
+	return 0;
+}
+
+static struct pmu perf_task_clock = {
+	.task_ctx_nr	= perf_sw_context,
+
+	.capabilities	= PERF_PMU_CAP_NO_NMI,
+
+	.event_init	= task_clock_event_init,
+	.add		= task_clock_event_add,
+	.del		= task_clock_event_del,
+	.start		= task_clock_event_start,
+	.stop		= task_clock_event_stop,
+	.read		= task_clock_event_read,
+};
+
+static void perf_pmu_nop_void(struct pmu *pmu)
+{
+}
+
+static void perf_pmu_nop_txn(struct pmu *pmu, unsigned int flags)
+{
+}
+
+static int perf_pmu_nop_int(struct pmu *pmu)
+{
+	return 0;
+}
+
+static int perf_event_nop_int(struct perf_event *event, u64 value)
+{
+	return 0;
+}
+
+static DEFINE_PER_CPU(unsigned int, nop_txn_flags);
+
+static void perf_pmu_start_txn(struct pmu *pmu, unsigned int flags)
+{
+	__this_cpu_write(nop_txn_flags, flags);
+
+	if (flags & ~PERF_PMU_TXN_ADD)
+		return;
+
+	perf_pmu_disable(pmu);
+}
+
+static int perf_pmu_commit_txn(struct pmu *pmu)
+{
+	unsigned int flags = __this_cpu_read(nop_txn_flags);
+
+	__this_cpu_write(nop_txn_flags, 0);
+
+	if (flags & ~PERF_PMU_TXN_ADD)
+		return 0;
+
+	perf_pmu_enable(pmu);
+	return 0;
+}
+
+static void perf_pmu_cancel_txn(struct pmu *pmu)
+{
+	unsigned int flags =  __this_cpu_read(nop_txn_flags);
+
+	__this_cpu_write(nop_txn_flags, 0);
+
+	if (flags & ~PERF_PMU_TXN_ADD)
+		return;
+
+	perf_pmu_enable(pmu);
+}
+
+static int perf_event_idx_default(struct perf_event *event)
+{
+	return 0;
+}
+
+/*
+ * Ensures all contexts with the same task_ctx_nr have the same
+ * pmu_cpu_context too.
+ */
+static struct perf_cpu_context __percpu *find_pmu_context(int ctxn)
+{
+	struct pmu *pmu;
+
+	if (ctxn < 0)
+		return NULL;
+
+	list_for_each_entry(pmu, &pmus, entry) {
+		if (pmu->task_ctx_nr == ctxn)
+			return pmu->pmu_cpu_context;
+	}
+
+	return NULL;
+}
+
+static void free_pmu_context(struct pmu *pmu)
+{
+	/*
+	 * Static contexts such as perf_sw_context have a global lifetime
+	 * and may be shared between different PMUs. Avoid freeing them
+	 * when a single PMU is going away.
+	 */
+	if (pmu->task_ctx_nr > perf_invalid_context)
+		return;
+
+	free_percpu(pmu->pmu_cpu_context);
+}
+
+/*
+ * Let userspace know that this PMU supports address range filtering:
+ */
+static ssize_t nr_addr_filters_show(struct device *dev,
+				    struct device_attribute *attr,
+				    char *page)
+{
+	struct pmu *pmu = dev_get_drvdata(dev);
+
+	return scnprintf(page, PAGE_SIZE - 1, "%d\n", pmu->nr_addr_filters);
+}
+DEVICE_ATTR_RO(nr_addr_filters);
+
+static struct idr pmu_idr;
+
+static ssize_t
+type_show(struct device *dev, struct device_attribute *attr, char *page)
+{
+	struct pmu *pmu = dev_get_drvdata(dev);
+
+	return scnprintf(page, PAGE_SIZE - 1, "%d\n", pmu->type);
+}
+static DEVICE_ATTR_RO(type);
+
+static ssize_t
+perf_event_mux_interval_ms_show(struct device *dev,
+				struct device_attribute *attr,
+				char *page)
+{
+	struct pmu *pmu = dev_get_drvdata(dev);
+
+	return scnprintf(page, PAGE_SIZE - 1, "%d\n", pmu->hrtimer_interval_ms);
+}
+
+static DEFINE_MUTEX(mux_interval_mutex);
+
+static ssize_t
+perf_event_mux_interval_ms_store(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf, size_t count)
+{
+	struct pmu *pmu = dev_get_drvdata(dev);
+	int timer, cpu, ret;
+
+	ret = kstrtoint(buf, 0, &timer);
+	if (ret)
+		return ret;
+
+	if (timer < 1)
+		return -EINVAL;
+
+	/* same value, noting to do */
+	if (timer == pmu->hrtimer_interval_ms)
+		return count;
+
+	mutex_lock(&mux_interval_mutex);
+	pmu->hrtimer_interval_ms = timer;
+
+	/* update all cpuctx for this PMU */
+	cpus_read_lock();
+	for_each_online_cpu(cpu) {
+		struct perf_cpu_context *cpuctx;
+		cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+		cpuctx->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * timer);
+
+		cpu_function_call(cpu, perf_mux_hrtimer_restart_ipi, cpuctx);
+	}
+	cpus_read_unlock();
+	mutex_unlock(&mux_interval_mutex);
+
+	return count;
+}
+static DEVICE_ATTR_RW(perf_event_mux_interval_ms);
+
+static struct attribute *pmu_dev_attrs[] = {
+	&dev_attr_type.attr,
+	&dev_attr_perf_event_mux_interval_ms.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(pmu_dev);
+
+static int pmu_bus_running;
+static struct bus_type pmu_bus = {
+	.name		= "event_source",
+	.dev_groups	= pmu_dev_groups,
+};
+
+static void pmu_dev_release(struct device *dev)
+{
+	kfree(dev);
+}
+
+static int pmu_dev_alloc(struct pmu *pmu)
+{
+	int ret = -ENOMEM;
+
+	pmu->dev = kzalloc(sizeof(struct device), GFP_KERNEL);
+	if (!pmu->dev)
+		goto out;
+
+	pmu->dev->groups = pmu->attr_groups;
+	device_initialize(pmu->dev);
+
+	dev_set_drvdata(pmu->dev, pmu);
+	pmu->dev->bus = &pmu_bus;
+	pmu->dev->release = pmu_dev_release;
+
+	ret = dev_set_name(pmu->dev, "%s", pmu->name);
+	if (ret)
+		goto free_dev;
+
+	ret = device_add(pmu->dev);
+	if (ret)
+		goto free_dev;
+
+	/* For PMUs with address filters, throw in an extra attribute: */
+	if (pmu->nr_addr_filters)
+		ret = device_create_file(pmu->dev, &dev_attr_nr_addr_filters);
+
+	if (ret)
+		goto del_dev;
+
+	if (pmu->attr_update)
+		ret = sysfs_update_groups(&pmu->dev->kobj, pmu->attr_update);
+
+	if (ret)
+		goto del_dev;
+
+out:
+	return ret;
+
+del_dev:
+	device_del(pmu->dev);
+
+free_dev:
+	put_device(pmu->dev);
+	goto out;
+}
+
+static struct lock_class_key cpuctx_mutex;
+static struct lock_class_key cpuctx_lock;
+
+int perf_pmu_register(struct pmu *pmu, const char *name, int type)
+{
+	int cpu, ret, max = PERF_TYPE_MAX;
+
+	mutex_lock(&pmus_lock);
+	ret = -ENOMEM;
+	pmu->pmu_disable_count = alloc_percpu(int);
+	if (!pmu->pmu_disable_count)
+		goto unlock;
+
+	pmu->type = -1;
+	if (!name)
+		goto skip_type;
+	pmu->name = name;
+
+	if (type != PERF_TYPE_SOFTWARE) {
+		if (type >= 0)
+			max = type;
+
+		ret = idr_alloc(&pmu_idr, pmu, max, 0, GFP_KERNEL);
+		if (ret < 0)
+			goto free_pdc;
+
+		WARN_ON(type >= 0 && ret != type);
+
+		type = ret;
+	}
+	pmu->type = type;
+
+	if (pmu_bus_running) {
+		ret = pmu_dev_alloc(pmu);
+		if (ret)
+			goto free_idr;
+	}
+
+skip_type:
+	if (pmu->task_ctx_nr == perf_hw_context) {
+		static int hw_context_taken = 0;
+
+		/*
+		 * Other than systems with heterogeneous CPUs, it never makes
+		 * sense for two PMUs to share perf_hw_context. PMUs which are
+		 * uncore must use perf_invalid_context.
+		 */
+		if (WARN_ON_ONCE(hw_context_taken &&
+		    !(pmu->capabilities & PERF_PMU_CAP_HETEROGENEOUS_CPUS)))
+			pmu->task_ctx_nr = perf_invalid_context;
+
+		hw_context_taken = 1;
+	}
+
+	pmu->pmu_cpu_context = find_pmu_context(pmu->task_ctx_nr);
+	if (pmu->pmu_cpu_context)
+		goto got_cpu_context;
+
+	ret = -ENOMEM;
+	pmu->pmu_cpu_context = alloc_percpu(struct perf_cpu_context);
+	if (!pmu->pmu_cpu_context)
+		goto free_dev;
+
+	for_each_possible_cpu(cpu) {
+		struct perf_cpu_context *cpuctx;
+
+		cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+		__perf_event_init_context(&cpuctx->ctx);
+		lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex);
+		lockdep_set_class(&cpuctx->ctx.lock, &cpuctx_lock);
+		cpuctx->ctx.pmu = pmu;
+		cpuctx->online = cpumask_test_cpu(cpu, perf_online_mask);
+
+		__perf_mux_hrtimer_init(cpuctx, cpu);
+
+		cpuctx->heap_size = ARRAY_SIZE(cpuctx->heap_default);
+		cpuctx->heap = cpuctx->heap_default;
+	}
+
+got_cpu_context:
+	if (!pmu->start_txn) {
+		if (pmu->pmu_enable) {
+			/*
+			 * If we have pmu_enable/pmu_disable calls, install
+			 * transaction stubs that use that to try and batch
+			 * hardware accesses.
+			 */
+			pmu->start_txn  = perf_pmu_start_txn;
+			pmu->commit_txn = perf_pmu_commit_txn;
+			pmu->cancel_txn = perf_pmu_cancel_txn;
+		} else {
+			pmu->start_txn  = perf_pmu_nop_txn;
+			pmu->commit_txn = perf_pmu_nop_int;
+			pmu->cancel_txn = perf_pmu_nop_void;
+		}
+	}
+
+	if (!pmu->pmu_enable) {
+		pmu->pmu_enable  = perf_pmu_nop_void;
+		pmu->pmu_disable = perf_pmu_nop_void;
+	}
+
+	if (!pmu->check_period)
+		pmu->check_period = perf_event_nop_int;
+
+	if (!pmu->event_idx)
+		pmu->event_idx = perf_event_idx_default;
+
+	/*
+	 * Ensure the TYPE_SOFTWARE PMUs are at the head of the list,
+	 * since these cannot be in the IDR. This way the linear search
+	 * is fast, provided a valid software event is provided.
+	 */
+	if (type == PERF_TYPE_SOFTWARE || !name)
+		list_add_rcu(&pmu->entry, &pmus);
+	else
+		list_add_tail_rcu(&pmu->entry, &pmus);
+
+	atomic_set(&pmu->exclusive_cnt, 0);
+	ret = 0;
+unlock:
+	mutex_unlock(&pmus_lock);
+
+	return ret;
+
+free_dev:
+	device_del(pmu->dev);
+	put_device(pmu->dev);
+
+free_idr:
+	if (pmu->type != PERF_TYPE_SOFTWARE)
+		idr_remove(&pmu_idr, pmu->type);
+
+free_pdc:
+	free_percpu(pmu->pmu_disable_count);
+	goto unlock;
+}
+EXPORT_SYMBOL_GPL(perf_pmu_register);
+
+void perf_pmu_unregister(struct pmu *pmu)
+{
+	mutex_lock(&pmus_lock);
+	list_del_rcu(&pmu->entry);
+
+	/*
+	 * We dereference the pmu list under both SRCU and regular RCU, so
+	 * synchronize against both of those.
+	 */
+	synchronize_srcu(&pmus_srcu);
+	synchronize_rcu();
+
+	free_percpu(pmu->pmu_disable_count);
+	if (pmu->type != PERF_TYPE_SOFTWARE)
+		idr_remove(&pmu_idr, pmu->type);
+	if (pmu_bus_running) {
+		if (pmu->nr_addr_filters)
+			device_remove_file(pmu->dev, &dev_attr_nr_addr_filters);
+		device_del(pmu->dev);
+		put_device(pmu->dev);
+	}
+	free_pmu_context(pmu);
+	mutex_unlock(&pmus_lock);
+}
+EXPORT_SYMBOL_GPL(perf_pmu_unregister);
+
+static inline bool has_extended_regs(struct perf_event *event)
+{
+	return (event->attr.sample_regs_user & PERF_REG_EXTENDED_MASK) ||
+	       (event->attr.sample_regs_intr & PERF_REG_EXTENDED_MASK);
+}
+
+static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
+{
+	struct perf_event_context *ctx = NULL;
+	int ret;
+
+	if (!try_module_get(pmu->module))
+		return -ENODEV;
+
+	/*
+	 * A number of pmu->event_init() methods iterate the sibling_list to,
+	 * for example, validate if the group fits on the PMU. Therefore,
+	 * if this is a sibling event, acquire the ctx->mutex to protect
+	 * the sibling_list.
+	 */
+	if (event->group_leader != event && pmu->task_ctx_nr != perf_sw_context) {
+		/*
+		 * This ctx->mutex can nest when we're called through
+		 * inheritance. See the perf_event_ctx_lock_nested() comment.
+		 */
+		ctx = perf_event_ctx_lock_nested(event->group_leader,
+						 SINGLE_DEPTH_NESTING);
+		BUG_ON(!ctx);
+	}
+
+	event->pmu = pmu;
+	ret = pmu->event_init(event);
+
+	if (ctx)
+		perf_event_ctx_unlock(event->group_leader, ctx);
+
+	if (!ret) {
+		if (!(pmu->capabilities & PERF_PMU_CAP_EXTENDED_REGS) &&
+		    has_extended_regs(event))
+			ret = -EOPNOTSUPP;
+
+		if (pmu->capabilities & PERF_PMU_CAP_NO_EXCLUDE &&
+		    event_has_any_exclude_flag(event))
+			ret = -EINVAL;
+
+		if (ret && event->destroy)
+			event->destroy(event);
+	}
+
+	if (ret)
+		module_put(pmu->module);
+
+	return ret;
+}
+
+static struct pmu *perf_init_event(struct perf_event *event)
+{
+	bool extended_type = false;
+	int idx, type, ret;
+	struct pmu *pmu;
+
+	idx = srcu_read_lock(&pmus_srcu);
+
+	/* Try parent's PMU first: */
+	if (event->parent && event->parent->pmu) {
+		pmu = event->parent->pmu;
+		ret = perf_try_init_event(pmu, event);
+		if (!ret)
+			goto unlock;
+	}
+
+	/*
+	 * PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE
+	 * are often aliases for PERF_TYPE_RAW.
+	 */
+	type = event->attr.type;
+	if (type == PERF_TYPE_HARDWARE || type == PERF_TYPE_HW_CACHE) {
+		type = event->attr.config >> PERF_PMU_TYPE_SHIFT;
+		if (!type) {
+			type = PERF_TYPE_RAW;
+		} else {
+			extended_type = true;
+			event->attr.config &= PERF_HW_EVENT_MASK;
+		}
+	}
+
+again:
+	rcu_read_lock();
+	pmu = idr_find(&pmu_idr, type);
+	rcu_read_unlock();
+	if (pmu) {
+		if (event->attr.type != type && type != PERF_TYPE_RAW &&
+		    !(pmu->capabilities & PERF_PMU_CAP_EXTENDED_HW_TYPE))
+			goto fail;
+
+		ret = perf_try_init_event(pmu, event);
+		if (ret == -ENOENT && event->attr.type != type && !extended_type) {
+			type = event->attr.type;
+			goto again;
+		}
+
+		if (ret)
+			pmu = ERR_PTR(ret);
+
+		goto unlock;
+	}
+
+	list_for_each_entry_rcu(pmu, &pmus, entry, lockdep_is_held(&pmus_srcu)) {
+		ret = perf_try_init_event(pmu, event);
+		if (!ret)
+			goto unlock;
+
+		if (ret != -ENOENT) {
+			pmu = ERR_PTR(ret);
+			goto unlock;
+		}
+	}
+fail:
+	pmu = ERR_PTR(-ENOENT);
+unlock:
+	srcu_read_unlock(&pmus_srcu, idx);
+
+	return pmu;
+}
+
+static void attach_sb_event(struct perf_event *event)
+{
+	struct pmu_event_list *pel = per_cpu_ptr(&pmu_sb_events, event->cpu);
+
+	raw_spin_lock(&pel->lock);
+	list_add_rcu(&event->sb_list, &pel->list);
+	raw_spin_unlock(&pel->lock);
+}
+
+/*
+ * We keep a list of all !task (and therefore per-cpu) events
+ * that need to receive side-band records.
+ *
+ * This avoids having to scan all the various PMU per-cpu contexts
+ * looking for them.
+ */
+static void account_pmu_sb_event(struct perf_event *event)
+{
+	if (is_sb_event(event))
+		attach_sb_event(event);
+}
+
+static void account_event_cpu(struct perf_event *event, int cpu)
+{
+	if (event->parent)
+		return;
+
+	if (is_cgroup_event(event))
+		atomic_inc(&per_cpu(perf_cgroup_events, cpu));
+}
+
+/* Freq events need the tick to stay alive (see perf_event_task_tick). */
+static void account_freq_event_nohz(void)
+{
+#ifdef CONFIG_NO_HZ_FULL
+	/* Lock so we don't race with concurrent unaccount */
+	spin_lock(&nr_freq_lock);
+	if (atomic_inc_return(&nr_freq_events) == 1)
+		tick_nohz_dep_set(TICK_DEP_BIT_PERF_EVENTS);
+	spin_unlock(&nr_freq_lock);
+#endif
+}
+
+static void account_freq_event(void)
+{
+	if (tick_nohz_full_enabled())
+		account_freq_event_nohz();
+	else
+		atomic_inc(&nr_freq_events);
+}
+
+
+static void account_event(struct perf_event *event)
+{
+	bool inc = false;
+
+	if (event->parent)
+		return;
+
+	if (event->attach_state & (PERF_ATTACH_TASK | PERF_ATTACH_SCHED_CB))
+		inc = true;
+	if (event->attr.mmap || event->attr.mmap_data)
+		atomic_inc(&nr_mmap_events);
+	if (event->attr.build_id)
+		atomic_inc(&nr_build_id_events);
+	if (event->attr.comm)
+		atomic_inc(&nr_comm_events);
+	if (event->attr.namespaces)
+		atomic_inc(&nr_namespaces_events);
+	if (event->attr.cgroup)
+		atomic_inc(&nr_cgroup_events);
+	if (event->attr.task)
+		atomic_inc(&nr_task_events);
+	if (event->attr.freq)
+		account_freq_event();
+	if (event->attr.context_switch) {
+		atomic_inc(&nr_switch_events);
+		inc = true;
+	}
+	if (has_branch_stack(event))
+		inc = true;
+	if (is_cgroup_event(event))
+		inc = true;
+	if (event->attr.ksymbol)
+		atomic_inc(&nr_ksymbol_events);
+	if (event->attr.bpf_event)
+		atomic_inc(&nr_bpf_events);
+	if (event->attr.text_poke)
+		atomic_inc(&nr_text_poke_events);
+
+	if (inc) {
+		/*
+		 * We need the mutex here because static_branch_enable()
+		 * must complete *before* the perf_sched_count increment
+		 * becomes visible.
+		 */
+		if (atomic_inc_not_zero(&perf_sched_count))
+			goto enabled;
+
+		mutex_lock(&perf_sched_mutex);
+		if (!atomic_read(&perf_sched_count)) {
+			static_branch_enable(&perf_sched_events);
+			/*
+			 * Guarantee that all CPUs observe they key change and
+			 * call the perf scheduling hooks before proceeding to
+			 * install events that need them.
+			 */
+			synchronize_rcu();
+		}
+		/*
+		 * Now that we have waited for the sync_sched(), allow further
+		 * increments to by-pass the mutex.
+		 */
+		atomic_inc(&perf_sched_count);
+		mutex_unlock(&perf_sched_mutex);
+	}
+enabled:
+
+	account_event_cpu(event, event->cpu);
+
+	account_pmu_sb_event(event);
+}
+
+/*
+ * Allocate and initialize an event structure
+ */
+static struct perf_event *
+perf_event_alloc(struct perf_event_attr *attr, int cpu,
+		 struct task_struct *task,
+		 struct perf_event *group_leader,
+		 struct perf_event *parent_event,
+		 perf_overflow_handler_t overflow_handler,
+		 void *context, int cgroup_fd)
+{
+	struct pmu *pmu;
+	struct perf_event *event;
+	struct hw_perf_event *hwc;
+	long err = -EINVAL;
+	int node;
+
+	if ((unsigned)cpu >= nr_cpu_ids) {
+		if (!task || cpu != -1)
+			return ERR_PTR(-EINVAL);
+	}
+	if (attr->sigtrap && !task) {
+		/* Requires a task: avoid signalling random tasks. */
+		return ERR_PTR(-EINVAL);
+	}
+
+	node = (cpu >= 0) ? cpu_to_node(cpu) : -1;
+	event = kmem_cache_alloc_node(perf_event_cache, GFP_KERNEL | __GFP_ZERO,
+				      node);
+	if (!event)
+		return ERR_PTR(-ENOMEM);
+
+	/*
+	 * Single events are their own group leaders, with an
+	 * empty sibling list:
+	 */
+	if (!group_leader)
+		group_leader = event;
+
+	mutex_init(&event->child_mutex);
+	INIT_LIST_HEAD(&event->child_list);
+
+	INIT_LIST_HEAD(&event->event_entry);
+	INIT_LIST_HEAD(&event->sibling_list);
+	INIT_LIST_HEAD(&event->active_list);
+	init_event_group(event);
+	INIT_LIST_HEAD(&event->rb_entry);
+	INIT_LIST_HEAD(&event->active_entry);
+	INIT_LIST_HEAD(&event->addr_filters.list);
+	INIT_HLIST_NODE(&event->hlist_entry);
+
+
+	init_waitqueue_head(&event->waitq);
+	init_irq_work(&event->pending_irq, perf_pending_irq);
+	init_task_work(&event->pending_task, perf_pending_task);
+
+	mutex_init(&event->mmap_mutex);
+	raw_spin_lock_init(&event->addr_filters.lock);
+
+	atomic_long_set(&event->refcount, 1);
+	event->cpu		= cpu;
+	event->attr		= *attr;
+	event->group_leader	= group_leader;
+	event->pmu		= NULL;
+	event->oncpu		= -1;
+
+	event->parent		= parent_event;
+
+	event->ns		= get_pid_ns(task_active_pid_ns(current));
+	event->id		= atomic64_inc_return(&perf_event_id);
+
+	event->state		= PERF_EVENT_STATE_INACTIVE;
+
+	if (parent_event)
+		event->event_caps = parent_event->event_caps;
+
+	if (task) {
+		event->attach_state = PERF_ATTACH_TASK;
+		/*
+		 * XXX pmu::event_init needs to know what task to account to
+		 * and we cannot use the ctx information because we need the
+		 * pmu before we get a ctx.
+		 */
+		event->hw.target = get_task_struct(task);
+	}
+
+	event->clock = &local_clock;
+	if (parent_event)
+		event->clock = parent_event->clock;
+
+	if (!overflow_handler && parent_event) {
+		overflow_handler = parent_event->overflow_handler;
+		context = parent_event->overflow_handler_context;
+#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_EVENT_TRACING)
+		if (overflow_handler == bpf_overflow_handler) {
+			struct bpf_prog *prog = parent_event->prog;
+
+			bpf_prog_inc(prog);
+			event->prog = prog;
+			event->orig_overflow_handler =
+				parent_event->orig_overflow_handler;
+		}
+#endif
+	}
+
+	if (overflow_handler) {
+		event->overflow_handler	= overflow_handler;
+		event->overflow_handler_context = context;
+	} else if (is_write_backward(event)){
+		event->overflow_handler = perf_event_output_backward;
+		event->overflow_handler_context = NULL;
+	} else {
+		event->overflow_handler = perf_event_output_forward;
+		event->overflow_handler_context = NULL;
+	}
+
+	perf_event__state_init(event);
+
+	pmu = NULL;
+
+	hwc = &event->hw;
+	hwc->sample_period = attr->sample_period;
+	if (attr->freq && attr->sample_freq)
+		hwc->sample_period = 1;
+	hwc->last_period = hwc->sample_period;
+
+	local64_set(&hwc->period_left, hwc->sample_period);
+
+	/*
+	 * We currently do not support PERF_SAMPLE_READ on inherited events.
+	 * See perf_output_read().
+	 */
+	if (attr->inherit && (attr->sample_type & PERF_SAMPLE_READ))
+		goto err_ns;
+
+	if (!has_branch_stack(event))
+		event->attr.branch_sample_type = 0;
+
+	pmu = perf_init_event(event);
+	if (IS_ERR(pmu)) {
+		err = PTR_ERR(pmu);
+		goto err_ns;
+	}
+
+	/*
+	 * Disallow uncore-cgroup events, they don't make sense as the cgroup will
+	 * be different on other CPUs in the uncore mask.
+	 */
+	if (pmu->task_ctx_nr == perf_invalid_context && cgroup_fd != -1) {
+		err = -EINVAL;
+		goto err_pmu;
+	}
+
+	if (event->attr.aux_output &&
+	    !(pmu->capabilities & PERF_PMU_CAP_AUX_OUTPUT)) {
+		err = -EOPNOTSUPP;
+		goto err_pmu;
+	}
+
+	if (cgroup_fd != -1) {
+		err = perf_cgroup_connect(cgroup_fd, event, attr, group_leader);
+		if (err)
+			goto err_pmu;
+	}
+
+	err = exclusive_event_init(event);
+	if (err)
+		goto err_pmu;
+
+	if (has_addr_filter(event)) {
+		event->addr_filter_ranges = kcalloc(pmu->nr_addr_filters,
+						    sizeof(struct perf_addr_filter_range),
+						    GFP_KERNEL);
+		if (!event->addr_filter_ranges) {
+			err = -ENOMEM;
+			goto err_per_task;
+		}
+
+		/*
+		 * Clone the parent's vma offsets: they are valid until exec()
+		 * even if the mm is not shared with the parent.
+		 */
+		if (event->parent) {
+			struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
+
+			raw_spin_lock_irq(&ifh->lock);
+			memcpy(event->addr_filter_ranges,
+			       event->parent->addr_filter_ranges,
+			       pmu->nr_addr_filters * sizeof(struct perf_addr_filter_range));
+			raw_spin_unlock_irq(&ifh->lock);
+		}
+
+		/* force hw sync on the address filters */
+		event->addr_filters_gen = 1;
+	}
+
+	if (!event->parent) {
+		if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
+			err = get_callchain_buffers(attr->sample_max_stack);
+			if (err)
+				goto err_addr_filters;
+		}
+	}
+
+	err = security_perf_event_alloc(event);
+	if (err)
+		goto err_callchain_buffer;
+
+	/* symmetric to unaccount_event() in _free_event() */
+	account_event(event);
+
+	return event;
+
+err_callchain_buffer:
+	if (!event->parent) {
+		if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
+			put_callchain_buffers();
+	}
+err_addr_filters:
+	kfree(event->addr_filter_ranges);
+
+err_per_task:
+	exclusive_event_destroy(event);
+
+err_pmu:
+	if (is_cgroup_event(event))
+		perf_detach_cgroup(event);
+	if (event->destroy)
+		event->destroy(event);
+	module_put(pmu->module);
+err_ns:
+	if (event->hw.target)
+		put_task_struct(event->hw.target);
+	call_rcu(&event->rcu_head, free_event_rcu);
+
+	return ERR_PTR(err);
+}
+
+static int perf_copy_attr(struct perf_event_attr __user *uattr,
+			  struct perf_event_attr *attr)
+{
+	u32 size;
+	int ret;
+
+	/* Zero the full structure, so that a short copy will be nice. */
+	memset(attr, 0, sizeof(*attr));
+
+	ret = get_user(size, &uattr->size);
+	if (ret)
+		return ret;
+
+	/* ABI compatibility quirk: */
+	if (!size)
+		size = PERF_ATTR_SIZE_VER0;
+	if (size < PERF_ATTR_SIZE_VER0 || size > PAGE_SIZE)
+		goto err_size;
+
+	ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size);
+	if (ret) {
+		if (ret == -E2BIG)
+			goto err_size;
+		return ret;
+	}
+
+	attr->size = size;
+
+	if (attr->__reserved_1 || attr->__reserved_2 || attr->__reserved_3)
+		return -EINVAL;
+
+	if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))
+		return -EINVAL;
+
+	if (attr->read_format & ~(PERF_FORMAT_MAX-1))
+		return -EINVAL;
+
+	if (attr->sample_type & PERF_SAMPLE_BRANCH_STACK) {
+		u64 mask = attr->branch_sample_type;
+
+		/* only using defined bits */
+		if (mask & ~(PERF_SAMPLE_BRANCH_MAX-1))
+			return -EINVAL;
+
+		/* at least one branch bit must be set */
+		if (!(mask & ~PERF_SAMPLE_BRANCH_PLM_ALL))
+			return -EINVAL;
+
+		/* propagate priv level, when not set for branch */
+		if (!(mask & PERF_SAMPLE_BRANCH_PLM_ALL)) {
+
+			/* exclude_kernel checked on syscall entry */
+			if (!attr->exclude_kernel)
+				mask |= PERF_SAMPLE_BRANCH_KERNEL;
+
+			if (!attr->exclude_user)
+				mask |= PERF_SAMPLE_BRANCH_USER;
+
+			if (!attr->exclude_hv)
+				mask |= PERF_SAMPLE_BRANCH_HV;
+			/*
+			 * adjust user setting (for HW filter setup)
+			 */
+			attr->branch_sample_type = mask;
+		}
+		/* privileged levels capture (kernel, hv): check permissions */
+		if (mask & PERF_SAMPLE_BRANCH_PERM_PLM) {
+			ret = perf_allow_kernel(attr);
+			if (ret)
+				return ret;
+		}
+	}
+
+	if (attr->sample_type & PERF_SAMPLE_REGS_USER) {
+		ret = perf_reg_validate(attr->sample_regs_user);
+		if (ret)
+			return ret;
+	}
+
+	if (attr->sample_type & PERF_SAMPLE_STACK_USER) {
+		if (!arch_perf_have_user_stack_dump())
+			return -ENOSYS;
+
+		/*
+		 * We have __u32 type for the size, but so far
+		 * we can only use __u16 as maximum due to the
+		 * __u16 sample size limit.
+		 */
+		if (attr->sample_stack_user >= USHRT_MAX)
+			return -EINVAL;
+		else if (!IS_ALIGNED(attr->sample_stack_user, sizeof(u64)))
+			return -EINVAL;
+	}
+
+	if (!attr->sample_max_stack)
+		attr->sample_max_stack = sysctl_perf_event_max_stack;
+
+	if (attr->sample_type & PERF_SAMPLE_REGS_INTR)
+		ret = perf_reg_validate(attr->sample_regs_intr);
+
+#ifndef CONFIG_CGROUP_PERF
+	if (attr->sample_type & PERF_SAMPLE_CGROUP)
+		return -EINVAL;
+#endif
+	if ((attr->sample_type & PERF_SAMPLE_WEIGHT) &&
+	    (attr->sample_type & PERF_SAMPLE_WEIGHT_STRUCT))
+		return -EINVAL;
+
+	if (!attr->inherit && attr->inherit_thread)
+		return -EINVAL;
+
+	if (attr->remove_on_exec && attr->enable_on_exec)
+		return -EINVAL;
+
+	if (attr->sigtrap && !attr->remove_on_exec)
+		return -EINVAL;
+
+out:
+	return ret;
+
+err_size:
+	put_user(sizeof(*attr), &uattr->size);
+	ret = -E2BIG;
+	goto out;
+}
+
+static void mutex_lock_double(struct mutex *a, struct mutex *b)
+{
+	if (b < a)
+		swap(a, b);
+
+	mutex_lock(a);
+	mutex_lock_nested(b, SINGLE_DEPTH_NESTING);
+}
+
+static int
+perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
+{
+	struct perf_buffer *rb = NULL;
+	int ret = -EINVAL;
+
+	if (!output_event) {
+		mutex_lock(&event->mmap_mutex);
+		goto set;
+	}
+
+	/* don't allow circular references */
+	if (event == output_event)
+		goto out;
+
+	/*
+	 * Don't allow cross-cpu buffers
+	 */
+	if (output_event->cpu != event->cpu)
+		goto out;
+
+	/*
+	 * If its not a per-cpu rb, it must be the same task.
+	 */
+	if (output_event->cpu == -1 && output_event->hw.target != event->hw.target)
+		goto out;
+
+	/*
+	 * Mixing clocks in the same buffer is trouble you don't need.
+	 */
+	if (output_event->clock != event->clock)
+		goto out;
+
+	/*
+	 * Either writing ring buffer from beginning or from end.
+	 * Mixing is not allowed.
+	 */
+	if (is_write_backward(output_event) != is_write_backward(event))
+		goto out;
+
+	/*
+	 * If both events generate aux data, they must be on the same PMU
+	 */
+	if (has_aux(event) && has_aux(output_event) &&
+	    event->pmu != output_event->pmu)
+		goto out;
+
+	/*
+	 * Hold both mmap_mutex to serialize against perf_mmap_close().  Since
+	 * output_event is already on rb->event_list, and the list iteration
+	 * restarts after every removal, it is guaranteed this new event is
+	 * observed *OR* if output_event is already removed, it's guaranteed we
+	 * observe !rb->mmap_count.
+	 */
+	mutex_lock_double(&event->mmap_mutex, &output_event->mmap_mutex);
+set:
+	/* Can't redirect output if we've got an active mmap() */
+	if (atomic_read(&event->mmap_count))
+		goto unlock;
+
+	if (output_event) {
+		/* get the rb we want to redirect to */
+		rb = ring_buffer_get(output_event);
+		if (!rb)
+			goto unlock;
+
+		/* did we race against perf_mmap_close() */
+		if (!atomic_read(&rb->mmap_count)) {
+			ring_buffer_put(rb);
+			goto unlock;
+		}
+	}
+
+	ring_buffer_attach(event, rb);
+
+	ret = 0;
+unlock:
+	mutex_unlock(&event->mmap_mutex);
+	if (output_event)
+		mutex_unlock(&output_event->mmap_mutex);
+
+out:
+	return ret;
+}
+
+static int perf_event_set_clock(struct perf_event *event, clockid_t clk_id)
+{
+	bool nmi_safe = false;
+
+	switch (clk_id) {
+	case CLOCK_MONOTONIC:
+		event->clock = &ktime_get_mono_fast_ns;
+		nmi_safe = true;
+		break;
+
+	case CLOCK_MONOTONIC_RAW:
+		event->clock = &ktime_get_raw_fast_ns;
+		nmi_safe = true;
+		break;
+
+	case CLOCK_REALTIME:
+		event->clock = &ktime_get_real_ns;
+		break;
+
+	case CLOCK_BOOTTIME:
+		event->clock = &ktime_get_boottime_ns;
+		break;
+
+	case CLOCK_TAI:
+		event->clock = &ktime_get_clocktai_ns;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	if (!nmi_safe && !(event->pmu->capabilities & PERF_PMU_CAP_NO_NMI))
+		return -EINVAL;
+
+	return 0;
+}
+
+/*
+ * Variation on perf_event_ctx_lock_nested(), except we take two context
+ * mutexes.
+ */
+static struct perf_event_context *
+__perf_event_ctx_lock_double(struct perf_event *group_leader,
+			     struct perf_event_context *ctx)
+{
+	struct perf_event_context *gctx;
+
+again:
+	rcu_read_lock();
+	gctx = READ_ONCE(group_leader->ctx);
+	if (!refcount_inc_not_zero(&gctx->refcount)) {
+		rcu_read_unlock();
+		goto again;
+	}
+	rcu_read_unlock();
+
+	mutex_lock_double(&gctx->mutex, &ctx->mutex);
+
+	if (group_leader->ctx != gctx) {
+		mutex_unlock(&ctx->mutex);
+		mutex_unlock(&gctx->mutex);
+		put_ctx(gctx);
+		goto again;
+	}
+
+	return gctx;
+}
+
+static bool
+perf_check_permission(struct perf_event_attr *attr, struct task_struct *task)
+{
+	unsigned int ptrace_mode = PTRACE_MODE_READ_REALCREDS;
+	bool is_capable = perfmon_capable();
+
+	if (attr->sigtrap) {
+		/*
+		 * perf_event_attr::sigtrap sends signals to the other task.
+		 * Require the current task to also have CAP_KILL.
+		 */
+		rcu_read_lock();
+		is_capable &= ns_capable(__task_cred(task)->user_ns, CAP_KILL);
+		rcu_read_unlock();
+
+		/*
+		 * If the required capabilities aren't available, checks for
+		 * ptrace permissions: upgrade to ATTACH, since sending signals
+		 * can effectively change the target task.
+		 */
+		ptrace_mode = PTRACE_MODE_ATTACH_REALCREDS;
+	}
+
+	/*
+	 * Preserve ptrace permission check for backwards compatibility. The
+	 * ptrace check also includes checks that the current task and other
+	 * task have matching uids, and is therefore not done here explicitly.
+	 */
+	return is_capable || ptrace_may_access(task, ptrace_mode);
+}
+
+/**
+ * sys_perf_event_open - open a performance event, associate it to a task/cpu
+ *
+ * @attr_uptr:	event_id type attributes for monitoring/sampling
+ * @pid:		target pid
+ * @cpu:		target cpu
+ * @group_fd:		group leader event fd
+ * @flags:		perf event open flags
+ */
+SYSCALL_DEFINE5(perf_event_open,
+		struct perf_event_attr __user *, attr_uptr,
+		pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
+{
+	struct perf_event *group_leader = NULL, *output_event = NULL;
+	struct perf_event *event, *sibling;
+	struct perf_event_attr attr;
+	struct perf_event_context *ctx, *gctx;
+	struct file *event_file = NULL;
+	struct fd group = {NULL, 0};
+	struct task_struct *task = NULL;
+	struct pmu *pmu;
+	int event_fd;
+	int move_group = 0;
+	int err;
+	int f_flags = O_RDWR;
+	int cgroup_fd = -1;
+
+	/* for future expandability... */
+	if (flags & ~PERF_FLAG_ALL)
+		return -EINVAL;
+
+	err = perf_copy_attr(attr_uptr, &attr);
+	if (err)
+		return err;
+
+	/* Do we allow access to perf_event_open(2) ? */
+	err = security_perf_event_open(&attr, PERF_SECURITY_OPEN);
+	if (err)
+		return err;
+
+	if (!attr.exclude_kernel) {
+		err = perf_allow_kernel(&attr);
+		if (err)
+			return err;
+	}
+
+	if (attr.namespaces) {
+		if (!perfmon_capable())
+			return -EACCES;
+	}
+
+	if (attr.freq) {
+		if (attr.sample_freq > sysctl_perf_event_sample_rate)
+			return -EINVAL;
+	} else {
+		if (attr.sample_period & (1ULL << 63))
+			return -EINVAL;
+	}
+
+	/* Only privileged users can get physical addresses */
+	if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR)) {
+		err = perf_allow_kernel(&attr);
+		if (err)
+			return err;
+	}
+
+	/* REGS_INTR can leak data, lockdown must prevent this */
+	if (attr.sample_type & PERF_SAMPLE_REGS_INTR) {
+		err = security_locked_down(LOCKDOWN_PERF);
+		if (err)
+			return err;
+	}
+
+	/*
+	 * In cgroup mode, the pid argument is used to pass the fd
+	 * opened to the cgroup directory in cgroupfs. The cpu argument
+	 * designates the cpu on which to monitor threads from that
+	 * cgroup.
+	 */
+	if ((flags & PERF_FLAG_PID_CGROUP) && (pid == -1 || cpu == -1))
+		return -EINVAL;
+
+	if (flags & PERF_FLAG_FD_CLOEXEC)
+		f_flags |= O_CLOEXEC;
+
+	event_fd = get_unused_fd_flags(f_flags);
+	if (event_fd < 0)
+		return event_fd;
+
+	if (group_fd != -1) {
+		err = perf_fget_light(group_fd, &group);
+		if (err)
+			goto err_fd;
+		group_leader = group.file->private_data;
+		if (flags & PERF_FLAG_FD_OUTPUT)
+			output_event = group_leader;
+		if (flags & PERF_FLAG_FD_NO_GROUP)
+			group_leader = NULL;
+	}
+
+	if (pid != -1 && !(flags & PERF_FLAG_PID_CGROUP)) {
+		task = find_lively_task_by_vpid(pid);
+		if (IS_ERR(task)) {
+			err = PTR_ERR(task);
+			goto err_group_fd;
+		}
+	}
+
+	if (task && group_leader &&
+	    group_leader->attr.inherit != attr.inherit) {
+		err = -EINVAL;
+		goto err_task;
+	}
+
+	if (flags & PERF_FLAG_PID_CGROUP)
+		cgroup_fd = pid;
+
+	event = perf_event_alloc(&attr, cpu, task, group_leader, NULL,
+				 NULL, NULL, cgroup_fd);
+	if (IS_ERR(event)) {
+		err = PTR_ERR(event);
+		goto err_task;
+	}
+
+	if (is_sampling_event(event)) {
+		if (event->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT) {
+			err = -EOPNOTSUPP;
+			goto err_alloc;
+		}
+	}
+
+	/*
+	 * Special case software events and allow them to be part of
+	 * any hardware group.
+	 */
+	pmu = event->pmu;
+
+	if (attr.use_clockid) {
+		err = perf_event_set_clock(event, attr.clockid);
+		if (err)
+			goto err_alloc;
+	}
+
+	if (pmu->task_ctx_nr == perf_sw_context)
+		event->event_caps |= PERF_EV_CAP_SOFTWARE;
+
+	if (group_leader) {
+		if (is_software_event(event) &&
+		    !in_software_context(group_leader)) {
+			/*
+			 * If the event is a sw event, but the group_leader
+			 * is on hw context.
+			 *
+			 * Allow the addition of software events to hw
+			 * groups, this is safe because software events
+			 * never fail to schedule.
+			 */
+			pmu = group_leader->ctx->pmu;
+		} else if (!is_software_event(event) &&
+			   is_software_event(group_leader) &&
+			   (group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
+			/*
+			 * In case the group is a pure software group, and we
+			 * try to add a hardware event, move the whole group to
+			 * the hardware context.
+			 */
+			move_group = 1;
+		}
+	}
+
+	/*
+	 * Get the target context (task or percpu):
+	 */
+	ctx = find_get_context(pmu, task, event);
+	if (IS_ERR(ctx)) {
+		err = PTR_ERR(ctx);
+		goto err_alloc;
+	}
+
+	/*
+	 * Look up the group leader (we will attach this event to it):
+	 */
+	if (group_leader) {
+		err = -EINVAL;
+
+		/*
+		 * Do not allow a recursive hierarchy (this new sibling
+		 * becoming part of another group-sibling):
+		 */
+		if (group_leader->group_leader != group_leader)
+			goto err_context;
+
+		/* All events in a group should have the same clock */
+		if (group_leader->clock != event->clock)
+			goto err_context;
+
+		/*
+		 * Make sure we're both events for the same CPU;
+		 * grouping events for different CPUs is broken; since
+		 * you can never concurrently schedule them anyhow.
+		 */
+		if (group_leader->cpu != event->cpu)
+			goto err_context;
+
+		/*
+		 * Make sure we're both on the same task, or both
+		 * per-CPU events.
+		 */
+		if (group_leader->ctx->task != ctx->task)
+			goto err_context;
+
+		/*
+		 * Do not allow to attach to a group in a different task
+		 * or CPU context. If we're moving SW events, we'll fix
+		 * this up later, so allow that.
+		 *
+		 * Racy, not holding group_leader->ctx->mutex, see comment with
+		 * perf_event_ctx_lock().
+		 */
+		if (!move_group && group_leader->ctx != ctx)
+			goto err_context;
+
+		/*
+		 * Only a group leader can be exclusive or pinned
+		 */
+		if (attr.exclusive || attr.pinned)
+			goto err_context;
+	}
+
+	if (output_event) {
+		err = perf_event_set_output(event, output_event);
+		if (err)
+			goto err_context;
+	}
+
+	event_file = anon_inode_getfile("[perf_event]", &perf_fops, event,
+					f_flags);
+	if (IS_ERR(event_file)) {
+		err = PTR_ERR(event_file);
+		event_file = NULL;
+		goto err_context;
+	}
+
+	if (task) {
+		err = down_read_interruptible(&task->signal->exec_update_lock);
+		if (err)
+			goto err_file;
+
+		/*
+		 * We must hold exec_update_lock across this and any potential
+		 * perf_install_in_context() call for this new event to
+		 * serialize against exec() altering our credentials (and the
+		 * perf_event_exit_task() that could imply).
+		 */
+		err = -EACCES;
+		if (!perf_check_permission(&attr, task))
+			goto err_cred;
+	}
+
+	if (move_group) {
+		gctx = __perf_event_ctx_lock_double(group_leader, ctx);
+
+		if (gctx->task == TASK_TOMBSTONE) {
+			err = -ESRCH;
+			goto err_locked;
+		}
+
+		/*
+		 * Check if we raced against another sys_perf_event_open() call
+		 * moving the software group underneath us.
+		 */
+		if (!(group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
+			/*
+			 * If someone moved the group out from under us, check
+			 * if this new event wound up on the same ctx, if so
+			 * its the regular !move_group case, otherwise fail.
+			 */
+			if (gctx != ctx) {
+				err = -EINVAL;
+				goto err_locked;
+			} else {
+				perf_event_ctx_unlock(group_leader, gctx);
+				move_group = 0;
+				goto not_move_group;
+			}
+		}
+
+		/*
+		 * Failure to create exclusive events returns -EBUSY.
+		 */
+		err = -EBUSY;
+		if (!exclusive_event_installable(group_leader, ctx))
+			goto err_locked;
+
+		for_each_sibling_event(sibling, group_leader) {
+			if (!exclusive_event_installable(sibling, ctx))
+				goto err_locked;
+		}
+	} else {
+		mutex_lock(&ctx->mutex);
+
+		/*
+		 * Now that we hold ctx->lock, (re)validate group_leader->ctx == ctx,
+		 * see the group_leader && !move_group test earlier.
+		 */
+		if (group_leader && group_leader->ctx != ctx) {
+			err = -EINVAL;
+			goto err_locked;
+		}
+	}
+not_move_group:
+
+	if (ctx->task == TASK_TOMBSTONE) {
+		err = -ESRCH;
+		goto err_locked;
+	}
+
+	if (!perf_event_validate_size(event)) {
+		err = -E2BIG;
+		goto err_locked;
+	}
+
+	if (!task) {
+		/*
+		 * Check if the @cpu we're creating an event for is online.
+		 *
+		 * We use the perf_cpu_context::ctx::mutex to serialize against
+		 * the hotplug notifiers. See perf_event_{init,exit}_cpu().
+		 */
+		struct perf_cpu_context *cpuctx =
+			container_of(ctx, struct perf_cpu_context, ctx);
+
+		if (!cpuctx->online) {
+			err = -ENODEV;
+			goto err_locked;
+		}
+	}
+
+	if (perf_need_aux_event(event) && !perf_get_aux_event(event, group_leader)) {
+		err = -EINVAL;
+		goto err_locked;
+	}
+
+	/*
+	 * Must be under the same ctx::mutex as perf_install_in_context(),
+	 * because we need to serialize with concurrent event creation.
+	 */
+	if (!exclusive_event_installable(event, ctx)) {
+		err = -EBUSY;
+		goto err_locked;
+	}
+
+	WARN_ON_ONCE(ctx->parent_ctx);
+
+	/*
+	 * This is the point on no return; we cannot fail hereafter. This is
+	 * where we start modifying current state.
+	 */
+
+	if (move_group) {
+		/*
+		 * See perf_event_ctx_lock() for comments on the details
+		 * of swizzling perf_event::ctx.
+		 */
+		perf_remove_from_context(group_leader, 0);
+		put_ctx(gctx);
+
+		for_each_sibling_event(sibling, group_leader) {
+			perf_remove_from_context(sibling, 0);
+			put_ctx(gctx);
+		}
+
+		/*
+		 * Wait for everybody to stop referencing the events through
+		 * the old lists, before installing it on new lists.
+		 */
+		synchronize_rcu();
+
+		/*
+		 * Install the group siblings before the group leader.
+		 *
+		 * Because a group leader will try and install the entire group
+		 * (through the sibling list, which is still in-tact), we can
+		 * end up with siblings installed in the wrong context.
+		 *
+		 * By installing siblings first we NO-OP because they're not
+		 * reachable through the group lists.
+		 */
+		for_each_sibling_event(sibling, group_leader) {
+			perf_event__state_init(sibling);
+			perf_install_in_context(ctx, sibling, sibling->cpu);
+			get_ctx(ctx);
+		}
+
+		/*
+		 * Removing from the context ends up with disabled
+		 * event. What we want here is event in the initial
+		 * startup state, ready to be add into new context.
+		 */
+		perf_event__state_init(group_leader);
+		perf_install_in_context(ctx, group_leader, group_leader->cpu);
+		get_ctx(ctx);
+	}
+
+	/*
+	 * Precalculate sample_data sizes; do while holding ctx::mutex such
+	 * that we're serialized against further additions and before
+	 * perf_install_in_context() which is the point the event is active and
+	 * can use these values.
+	 */
+	perf_event__header_size(event);
+	perf_event__id_header_size(event);
+
+	event->owner = current;
+
+	perf_install_in_context(ctx, event, event->cpu);
+	perf_unpin_context(ctx);
+
+	if (move_group)
+		perf_event_ctx_unlock(group_leader, gctx);
+	mutex_unlock(&ctx->mutex);
+
+	if (task) {
+		up_read(&task->signal->exec_update_lock);
+		put_task_struct(task);
+	}
+
+	mutex_lock(&current->perf_event_mutex);
+	list_add_tail(&event->owner_entry, &current->perf_event_list);
+	mutex_unlock(&current->perf_event_mutex);
+
+	/*
+	 * Drop the reference on the group_event after placing the
+	 * new event on the sibling_list. This ensures destruction
+	 * of the group leader will find the pointer to itself in
+	 * perf_group_detach().
+	 */
+	fdput(group);
+	fd_install(event_fd, event_file);
+	return event_fd;
+
+err_locked:
+	if (move_group)
+		perf_event_ctx_unlock(group_leader, gctx);
+	mutex_unlock(&ctx->mutex);
+err_cred:
+	if (task)
+		up_read(&task->signal->exec_update_lock);
+err_file:
+	fput(event_file);
+err_context:
+	perf_unpin_context(ctx);
+	put_ctx(ctx);
+err_alloc:
+	/*
+	 * If event_file is set, the fput() above will have called ->release()
+	 * and that will take care of freeing the event.
+	 */
+	if (!event_file)
+		free_event(event);
+err_task:
+	if (task)
+		put_task_struct(task);
+err_group_fd:
+	fdput(group);
+err_fd:
+	put_unused_fd(event_fd);
+	return err;
+}
+
+/**
+ * perf_event_create_kernel_counter
+ *
+ * @attr: attributes of the counter to create
+ * @cpu: cpu in which the counter is bound
+ * @task: task to profile (NULL for percpu)
+ * @overflow_handler: callback to trigger when we hit the event
+ * @context: context data could be used in overflow_handler callback
+ */
+struct perf_event *
+perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
+				 struct task_struct *task,
+				 perf_overflow_handler_t overflow_handler,
+				 void *context)
+{
+	struct perf_event_context *ctx;
+	struct perf_event *event;
+	int err;
+
+	/*
+	 * Grouping is not supported for kernel events, neither is 'AUX',
+	 * make sure the caller's intentions are adjusted.
+	 */
+	if (attr->aux_output)
+		return ERR_PTR(-EINVAL);
+
+	event = perf_event_alloc(attr, cpu, task, NULL, NULL,
+				 overflow_handler, context, -1);
+	if (IS_ERR(event)) {
+		err = PTR_ERR(event);
+		goto err;
+	}
+
+	/* Mark owner so we could distinguish it from user events. */
+	event->owner = TASK_TOMBSTONE;
+
+	/*
+	 * Get the target context (task or percpu):
+	 */
+	ctx = find_get_context(event->pmu, task, event);
+	if (IS_ERR(ctx)) {
+		err = PTR_ERR(ctx);
+		goto err_free;
+	}
+
+	WARN_ON_ONCE(ctx->parent_ctx);
+	mutex_lock(&ctx->mutex);
+	if (ctx->task == TASK_TOMBSTONE) {
+		err = -ESRCH;
+		goto err_unlock;
+	}
+
+	if (!task) {
+		/*
+		 * Check if the @cpu we're creating an event for is online.
+		 *
+		 * We use the perf_cpu_context::ctx::mutex to serialize against
+		 * the hotplug notifiers. See perf_event_{init,exit}_cpu().
+		 */
+		struct perf_cpu_context *cpuctx =
+			container_of(ctx, struct perf_cpu_context, ctx);
+		if (!cpuctx->online) {
+			err = -ENODEV;
+			goto err_unlock;
+		}
+	}
+
+	if (!exclusive_event_installable(event, ctx)) {
+		err = -EBUSY;
+		goto err_unlock;
+	}
+
+	perf_install_in_context(ctx, event, event->cpu);
+	perf_unpin_context(ctx);
+	mutex_unlock(&ctx->mutex);
+
+	return event;
+
+err_unlock:
+	mutex_unlock(&ctx->mutex);
+	perf_unpin_context(ctx);
+	put_ctx(ctx);
+err_free:
+	free_event(event);
+err:
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
+
+void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu)
+{
+	struct perf_event_context *src_ctx;
+	struct perf_event_context *dst_ctx;
+	struct perf_event *event, *tmp;
+	LIST_HEAD(events);
+
+	src_ctx = &per_cpu_ptr(pmu->pmu_cpu_context, src_cpu)->ctx;
+	dst_ctx = &per_cpu_ptr(pmu->pmu_cpu_context, dst_cpu)->ctx;
+
+	/*
+	 * See perf_event_ctx_lock() for comments on the details
+	 * of swizzling perf_event::ctx.
+	 */
+	mutex_lock_double(&src_ctx->mutex, &dst_ctx->mutex);
+	list_for_each_entry_safe(event, tmp, &src_ctx->event_list,
+				 event_entry) {
+		perf_remove_from_context(event, 0);
+		unaccount_event_cpu(event, src_cpu);
+		put_ctx(src_ctx);
+		list_add(&event->migrate_entry, &events);
+	}
+
+	/*
+	 * Wait for the events to quiesce before re-instating them.
+	 */
+	synchronize_rcu();
+
+	/*
+	 * Re-instate events in 2 passes.
+	 *
+	 * Skip over group leaders and only install siblings on this first
+	 * pass, siblings will not get enabled without a leader, however a
+	 * leader will enable its siblings, even if those are still on the old
+	 * context.
+	 */
+	list_for_each_entry_safe(event, tmp, &events, migrate_entry) {
+		if (event->group_leader == event)
+			continue;
+
+		list_del(&event->migrate_entry);
+		if (event->state >= PERF_EVENT_STATE_OFF)
+			event->state = PERF_EVENT_STATE_INACTIVE;
+		account_event_cpu(event, dst_cpu);
+		perf_install_in_context(dst_ctx, event, dst_cpu);
+		get_ctx(dst_ctx);
+	}
+
+	/*
+	 * Once all the siblings are setup properly, install the group leaders
+	 * to make it go.
+	 */
+	list_for_each_entry_safe(event, tmp, &events, migrate_entry) {
+		list_del(&event->migrate_entry);
+		if (event->state >= PERF_EVENT_STATE_OFF)
+			event->state = PERF_EVENT_STATE_INACTIVE;
+		account_event_cpu(event, dst_cpu);
+		perf_install_in_context(dst_ctx, event, dst_cpu);
+		get_ctx(dst_ctx);
+	}
+	mutex_unlock(&dst_ctx->mutex);
+	mutex_unlock(&src_ctx->mutex);
+}
+EXPORT_SYMBOL_GPL(perf_pmu_migrate_context);
+
+static void sync_child_event(struct perf_event *child_event)
+{
+	struct perf_event *parent_event = child_event->parent;
+	u64 child_val;
+
+	if (child_event->attr.inherit_stat) {
+		struct task_struct *task = child_event->ctx->task;
+
+		if (task && task != TASK_TOMBSTONE)
+			perf_event_read_event(child_event, task);
+	}
+
+	child_val = perf_event_count(child_event);
+
+	/*
+	 * Add back the child's count to the parent's count:
+	 */
+	atomic64_add(child_val, &parent_event->child_count);
+	atomic64_add(child_event->total_time_enabled,
+		     &parent_event->child_total_time_enabled);
+	atomic64_add(child_event->total_time_running,
+		     &parent_event->child_total_time_running);
+}
+
+static void
+perf_event_exit_event(struct perf_event *event, struct perf_event_context *ctx)
+{
+	struct perf_event *parent_event = event->parent;
+	unsigned long detach_flags = 0;
+
+	if (parent_event) {
+		/*
+		 * Do not destroy the 'original' grouping; because of the
+		 * context switch optimization the original events could've
+		 * ended up in a random child task.
+		 *
+		 * If we were to destroy the original group, all group related
+		 * operations would cease to function properly after this
+		 * random child dies.
+		 *
+		 * Do destroy all inherited groups, we don't care about those
+		 * and being thorough is better.
+		 */
+		detach_flags = DETACH_GROUP | DETACH_CHILD;
+		mutex_lock(&parent_event->child_mutex);
+	}
+
+	perf_remove_from_context(event, detach_flags);
+
+	raw_spin_lock_irq(&ctx->lock);
+	if (event->state > PERF_EVENT_STATE_EXIT)
+		perf_event_set_state(event, PERF_EVENT_STATE_EXIT);
+	raw_spin_unlock_irq(&ctx->lock);
+
+	/*
+	 * Child events can be freed.
+	 */
+	if (parent_event) {
+		mutex_unlock(&parent_event->child_mutex);
+		/*
+		 * Kick perf_poll() for is_event_hup();
+		 */
+		perf_event_wakeup(parent_event);
+		free_event(event);
+		put_event(parent_event);
+		return;
+	}
+
+	/*
+	 * Parent events are governed by their filedesc, retain them.
+	 */
+	perf_event_wakeup(event);
+}
+
+static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
+{
+	struct perf_event_context *child_ctx, *clone_ctx = NULL;
+	struct perf_event *child_event, *next;
+
+	WARN_ON_ONCE(child != current);
+
+	child_ctx = perf_pin_task_context(child, ctxn);
+	if (!child_ctx)
+		return;
+
+	/*
+	 * In order to reduce the amount of tricky in ctx tear-down, we hold
+	 * ctx::mutex over the entire thing. This serializes against almost
+	 * everything that wants to access the ctx.
+	 *
+	 * The exception is sys_perf_event_open() /
+	 * perf_event_create_kernel_count() which does find_get_context()
+	 * without ctx::mutex (it cannot because of the move_group double mutex
+	 * lock thing). See the comments in perf_install_in_context().
+	 */
+	mutex_lock(&child_ctx->mutex);
+
+	/*
+	 * In a single ctx::lock section, de-schedule the events and detach the
+	 * context from the task such that we cannot ever get it scheduled back
+	 * in.
+	 */
+	raw_spin_lock_irq(&child_ctx->lock);
+	task_ctx_sched_out(__get_cpu_context(child_ctx), child_ctx, EVENT_ALL);
+
+	/*
+	 * Now that the context is inactive, destroy the task <-> ctx relation
+	 * and mark the context dead.
+	 */
+	RCU_INIT_POINTER(child->perf_event_ctxp[ctxn], NULL);
+	put_ctx(child_ctx); /* cannot be last */
+	WRITE_ONCE(child_ctx->task, TASK_TOMBSTONE);
+	put_task_struct(current); /* cannot be last */
+
+	clone_ctx = unclone_ctx(child_ctx);
+	raw_spin_unlock_irq(&child_ctx->lock);
+
+	if (clone_ctx)
+		put_ctx(clone_ctx);
+
+	/*
+	 * Report the task dead after unscheduling the events so that we
+	 * won't get any samples after PERF_RECORD_EXIT. We can however still
+	 * get a few PERF_RECORD_READ events.
+	 */
+	perf_event_task(child, child_ctx, 0);
+
+	list_for_each_entry_safe(child_event, next, &child_ctx->event_list, event_entry)
+		perf_event_exit_event(child_event, child_ctx);
+
+	mutex_unlock(&child_ctx->mutex);
+
+	put_ctx(child_ctx);
+}
+
+/*
+ * When a child task exits, feed back event values to parent events.
+ *
+ * Can be called with exec_update_lock held when called from
+ * setup_new_exec().
+ */
+void perf_event_exit_task(struct task_struct *child)
+{
+	struct perf_event *event, *tmp;
+	int ctxn;
+
+	mutex_lock(&child->perf_event_mutex);
+	list_for_each_entry_safe(event, tmp, &child->perf_event_list,
+				 owner_entry) {
+		list_del_init(&event->owner_entry);
+
+		/*
+		 * Ensure the list deletion is visible before we clear
+		 * the owner, closes a race against perf_release() where
+		 * we need to serialize on the owner->perf_event_mutex.
+		 */
+		smp_store_release(&event->owner, NULL);
+	}
+	mutex_unlock(&child->perf_event_mutex);
+
+	for_each_task_context_nr(ctxn)
+		perf_event_exit_task_context(child, ctxn);
+
+	/*
+	 * The perf_event_exit_task_context calls perf_event_task
+	 * with child's task_ctx, which generates EXIT events for
+	 * child contexts and sets child->perf_event_ctxp[] to NULL.
+	 * At this point we need to send EXIT events to cpu contexts.
+	 */
+	perf_event_task(child, NULL, 0);
+}
+
+static void perf_free_event(struct perf_event *event,
+			    struct perf_event_context *ctx)
+{
+	struct perf_event *parent = event->parent;
+
+	if (WARN_ON_ONCE(!parent))
+		return;
+
+	mutex_lock(&parent->child_mutex);
+	list_del_init(&event->child_list);
+	mutex_unlock(&parent->child_mutex);
+
+	put_event(parent);
+
+	raw_spin_lock_irq(&ctx->lock);
+	perf_group_detach(event);
+	list_del_event(event, ctx);
+	raw_spin_unlock_irq(&ctx->lock);
+	free_event(event);
+}
+
+/*
+ * Free a context as created by inheritance by perf_event_init_task() below,
+ * used by fork() in case of fail.
+ *
+ * Even though the task has never lived, the context and events have been
+ * exposed through the child_list, so we must take care tearing it all down.
+ */
+void perf_event_free_task(struct task_struct *task)
+{
+	struct perf_event_context *ctx;
+	struct perf_event *event, *tmp;
+	int ctxn;
+
+	for_each_task_context_nr(ctxn) {
+		ctx = task->perf_event_ctxp[ctxn];
+		if (!ctx)
+			continue;
+
+		mutex_lock(&ctx->mutex);
+		raw_spin_lock_irq(&ctx->lock);
+		/*
+		 * Destroy the task <-> ctx relation and mark the context dead.
+		 *
+		 * This is important because even though the task hasn't been
+		 * exposed yet the context has been (through child_list).
+		 */
+		RCU_INIT_POINTER(task->perf_event_ctxp[ctxn], NULL);
+		WRITE_ONCE(ctx->task, TASK_TOMBSTONE);
+		put_task_struct(task); /* cannot be last */
+		raw_spin_unlock_irq(&ctx->lock);
+
+		list_for_each_entry_safe(event, tmp, &ctx->event_list, event_entry)
+			perf_free_event(event, ctx);
+
+		mutex_unlock(&ctx->mutex);
+
+		/*
+		 * perf_event_release_kernel() could've stolen some of our
+		 * child events and still have them on its free_list. In that
+		 * case we must wait for these events to have been freed (in
+		 * particular all their references to this task must've been
+		 * dropped).
+		 *
+		 * Without this copy_process() will unconditionally free this
+		 * task (irrespective of its reference count) and
+		 * _free_event()'s put_task_struct(event->hw.target) will be a
+		 * use-after-free.
+		 *
+		 * Wait for all events to drop their context reference.
+		 */
+		wait_var_event(&ctx->refcount, refcount_read(&ctx->refcount) == 1);
+		put_ctx(ctx); /* must be last */
+	}
+}
+
+void perf_event_delayed_put(struct task_struct *task)
+{
+	int ctxn;
+
+	for_each_task_context_nr(ctxn)
+		WARN_ON_ONCE(task->perf_event_ctxp[ctxn]);
+}
+
+struct file *perf_event_get(unsigned int fd)
+{
+	struct file *file = fget(fd);
+	if (!file)
+		return ERR_PTR(-EBADF);
+
+	if (file->f_op != &perf_fops) {
+		fput(file);
+		return ERR_PTR(-EBADF);
+	}
+
+	return file;
+}
+
+const struct perf_event *perf_get_event(struct file *file)
+{
+	if (file->f_op != &perf_fops)
+		return ERR_PTR(-EINVAL);
+
+	return file->private_data;
+}
+
+const struct perf_event_attr *perf_event_attrs(struct perf_event *event)
+{
+	if (!event)
+		return ERR_PTR(-EINVAL);
+
+	return &event->attr;
+}
+
+/*
+ * Inherit an event from parent task to child task.
+ *
+ * Returns:
+ *  - valid pointer on success
+ *  - NULL for orphaned events
+ *  - IS_ERR() on error
+ */
+static struct perf_event *
+inherit_event(struct perf_event *parent_event,
+	      struct task_struct *parent,
+	      struct perf_event_context *parent_ctx,
+	      struct task_struct *child,
+	      struct perf_event *group_leader,
+	      struct perf_event_context *child_ctx)
+{
+	enum perf_event_state parent_state = parent_event->state;
+	struct perf_event *child_event;
+	unsigned long flags;
+
+	/*
+	 * Instead of creating recursive hierarchies of events,
+	 * we link inherited events back to the original parent,
+	 * which has a filp for sure, which we use as the reference
+	 * count:
+	 */
+	if (parent_event->parent)
+		parent_event = parent_event->parent;
+
+	child_event = perf_event_alloc(&parent_event->attr,
+					   parent_event->cpu,
+					   child,
+					   group_leader, parent_event,
+					   NULL, NULL, -1);
+	if (IS_ERR(child_event))
+		return child_event;
+
+
+	if ((child_event->attach_state & PERF_ATTACH_TASK_DATA) &&
+	    !child_ctx->task_ctx_data) {
+		struct pmu *pmu = child_event->pmu;
+
+		child_ctx->task_ctx_data = alloc_task_ctx_data(pmu);
+		if (!child_ctx->task_ctx_data) {
+			free_event(child_event);
+			return ERR_PTR(-ENOMEM);
+		}
+	}
+
+	/*
+	 * is_orphaned_event() and list_add_tail(&parent_event->child_list)
+	 * must be under the same lock in order to serialize against
+	 * perf_event_release_kernel(), such that either we must observe
+	 * is_orphaned_event() or they will observe us on the child_list.
+	 */
+	mutex_lock(&parent_event->child_mutex);
+	if (is_orphaned_event(parent_event) ||
+	    !atomic_long_inc_not_zero(&parent_event->refcount)) {
+		mutex_unlock(&parent_event->child_mutex);
+		/* task_ctx_data is freed with child_ctx */
+		free_event(child_event);
+		return NULL;
+	}
+
+	get_ctx(child_ctx);
+
+	/*
+	 * Make the child state follow the state of the parent event,
+	 * not its attr.disabled bit.  We hold the parent's mutex,
+	 * so we won't race with perf_event_{en, dis}able_family.
+	 */
+	if (parent_state >= PERF_EVENT_STATE_INACTIVE)
+		child_event->state = PERF_EVENT_STATE_INACTIVE;
+	else
+		child_event->state = PERF_EVENT_STATE_OFF;
+
+	if (parent_event->attr.freq) {
+		u64 sample_period = parent_event->hw.sample_period;
+		struct hw_perf_event *hwc = &child_event->hw;
+
+		hwc->sample_period = sample_period;
+		hwc->last_period   = sample_period;
+
+		local64_set(&hwc->period_left, sample_period);
+	}
+
+	child_event->ctx = child_ctx;
+	child_event->overflow_handler = parent_event->overflow_handler;
+	child_event->overflow_handler_context
+		= parent_event->overflow_handler_context;
+
+	/*
+	 * Precalculate sample_data sizes
+	 */
+	perf_event__header_size(child_event);
+	perf_event__id_header_size(child_event);
+
+	/*
+	 * Link it up in the child's context:
+	 */
+	raw_spin_lock_irqsave(&child_ctx->lock, flags);
+	add_event_to_ctx(child_event, child_ctx);
+	child_event->attach_state |= PERF_ATTACH_CHILD;
+	raw_spin_unlock_irqrestore(&child_ctx->lock, flags);
+
+	/*
+	 * Link this into the parent event's child list
+	 */
+	list_add_tail(&child_event->child_list, &parent_event->child_list);
+	mutex_unlock(&parent_event->child_mutex);
+
+	return child_event;
+}
+
+/*
+ * Inherits an event group.
+ *
+ * This will quietly suppress orphaned events; !inherit_event() is not an error.
+ * This matches with perf_event_release_kernel() removing all child events.
+ *
+ * Returns:
+ *  - 0 on success
+ *  - <0 on error
+ */
+static int inherit_group(struct perf_event *parent_event,
+	      struct task_struct *parent,
+	      struct perf_event_context *parent_ctx,
+	      struct task_struct *child,
+	      struct perf_event_context *child_ctx)
+{
+	struct perf_event *leader;
+	struct perf_event *sub;
+	struct perf_event *child_ctr;
+
+	leader = inherit_event(parent_event, parent, parent_ctx,
+				 child, NULL, child_ctx);
+	if (IS_ERR(leader))
+		return PTR_ERR(leader);
+	/*
+	 * @leader can be NULL here because of is_orphaned_event(). In this
+	 * case inherit_event() will create individual events, similar to what
+	 * perf_group_detach() would do anyway.
+	 */
+	for_each_sibling_event(sub, parent_event) {
+		child_ctr = inherit_event(sub, parent, parent_ctx,
+					    child, leader, child_ctx);
+		if (IS_ERR(child_ctr))
+			return PTR_ERR(child_ctr);
+
+		if (sub->aux_event == parent_event && child_ctr &&
+		    !perf_get_aux_event(child_ctr, leader))
+			return -EINVAL;
+	}
+	if (leader)
+		leader->group_generation = parent_event->group_generation;
+	return 0;
+}
+
+/*
+ * Creates the child task context and tries to inherit the event-group.
+ *
+ * Clears @inherited_all on !attr.inherited or error. Note that we'll leave
+ * inherited_all set when we 'fail' to inherit an orphaned event; this is
+ * consistent with perf_event_release_kernel() removing all child events.
+ *
+ * Returns:
+ *  - 0 on success
+ *  - <0 on error
+ */
+static int
+inherit_task_group(struct perf_event *event, struct task_struct *parent,
+		   struct perf_event_context *parent_ctx,
+		   struct task_struct *child, int ctxn,
+		   u64 clone_flags, int *inherited_all)
+{
+	int ret;
+	struct perf_event_context *child_ctx;
+
+	if (!event->attr.inherit ||
+	    (event->attr.inherit_thread && !(clone_flags & CLONE_THREAD)) ||
+	    /* Do not inherit if sigtrap and signal handlers were cleared. */
+	    (event->attr.sigtrap && (clone_flags & CLONE_CLEAR_SIGHAND))) {
+		*inherited_all = 0;
+		return 0;
+	}
+
+	child_ctx = child->perf_event_ctxp[ctxn];
+	if (!child_ctx) {
+		/*
+		 * This is executed from the parent task context, so
+		 * inherit events that have been marked for cloning.
+		 * First allocate and initialize a context for the
+		 * child.
+		 */
+		child_ctx = alloc_perf_context(parent_ctx->pmu, child);
+		if (!child_ctx)
+			return -ENOMEM;
+
+		child->perf_event_ctxp[ctxn] = child_ctx;
+	}
+
+	ret = inherit_group(event, parent, parent_ctx,
+			    child, child_ctx);
+
+	if (ret)
+		*inherited_all = 0;
+
+	return ret;
+}
+
+/*
+ * Initialize the perf_event context in task_struct
+ */
+static int perf_event_init_context(struct task_struct *child, int ctxn,
+				   u64 clone_flags)
+{
+	struct perf_event_context *child_ctx, *parent_ctx;
+	struct perf_event_context *cloned_ctx;
+	struct perf_event *event;
+	struct task_struct *parent = current;
+	int inherited_all = 1;
+	unsigned long flags;
+	int ret = 0;
+
+	if (likely(!parent->perf_event_ctxp[ctxn]))
+		return 0;
+
+	/*
+	 * If the parent's context is a clone, pin it so it won't get
+	 * swapped under us.
+	 */
+	parent_ctx = perf_pin_task_context(parent, ctxn);
+	if (!parent_ctx)
+		return 0;
+
+	/*
+	 * No need to check if parent_ctx != NULL here; since we saw
+	 * it non-NULL earlier, the only reason for it to become NULL
+	 * is if we exit, and since we're currently in the middle of
+	 * a fork we can't be exiting at the same time.
+	 */
+
+	/*
+	 * Lock the parent list. No need to lock the child - not PID
+	 * hashed yet and not running, so nobody can access it.
+	 */
+	mutex_lock(&parent_ctx->mutex);
+
+	/*
+	 * We dont have to disable NMIs - we are only looking at
+	 * the list, not manipulating it:
+	 */
+	perf_event_groups_for_each(event, &parent_ctx->pinned_groups) {
+		ret = inherit_task_group(event, parent, parent_ctx,
+					 child, ctxn, clone_flags,
+					 &inherited_all);
+		if (ret)
+			goto out_unlock;
+	}
+
+	/*
+	 * We can't hold ctx->lock when iterating the ->flexible_group list due
+	 * to allocations, but we need to prevent rotation because
+	 * rotate_ctx() will change the list from interrupt context.
+	 */
+	raw_spin_lock_irqsave(&parent_ctx->lock, flags);
+	parent_ctx->rotate_disable = 1;
+	raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
+
+	perf_event_groups_for_each(event, &parent_ctx->flexible_groups) {
+		ret = inherit_task_group(event, parent, parent_ctx,
+					 child, ctxn, clone_flags,
+					 &inherited_all);
+		if (ret)
+			goto out_unlock;
+	}
+
+	raw_spin_lock_irqsave(&parent_ctx->lock, flags);
+	parent_ctx->rotate_disable = 0;
+
+	child_ctx = child->perf_event_ctxp[ctxn];
+
+	if (child_ctx && inherited_all) {
+		/*
+		 * Mark the child context as a clone of the parent
+		 * context, or of whatever the parent is a clone of.
+		 *
+		 * Note that if the parent is a clone, the holding of
+		 * parent_ctx->lock avoids it from being uncloned.
+		 */
+		cloned_ctx = parent_ctx->parent_ctx;
+		if (cloned_ctx) {
+			child_ctx->parent_ctx = cloned_ctx;
+			child_ctx->parent_gen = parent_ctx->parent_gen;
+		} else {
+			child_ctx->parent_ctx = parent_ctx;
+			child_ctx->parent_gen = parent_ctx->generation;
+		}
+		get_ctx(child_ctx->parent_ctx);
+	}
+
+	raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
+out_unlock:
+	mutex_unlock(&parent_ctx->mutex);
+
+	perf_unpin_context(parent_ctx);
+	put_ctx(parent_ctx);
+
+	return ret;
+}
+
+/*
+ * Initialize the perf_event context in task_struct
+ */
+int perf_event_init_task(struct task_struct *child, u64 clone_flags)
+{
+	int ctxn, ret;
+
+	memset(child->perf_event_ctxp, 0, sizeof(child->perf_event_ctxp));
+	mutex_init(&child->perf_event_mutex);
+	INIT_LIST_HEAD(&child->perf_event_list);
+
+	for_each_task_context_nr(ctxn) {
+		ret = perf_event_init_context(child, ctxn, clone_flags);
+		if (ret) {
+			perf_event_free_task(child);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static void __init perf_event_init_all_cpus(void)
+{
+	struct swevent_htable *swhash;
+	int cpu;
+
+	zalloc_cpumask_var(&perf_online_mask, GFP_KERNEL);
+
+	for_each_possible_cpu(cpu) {
+		swhash = &per_cpu(swevent_htable, cpu);
+		mutex_init(&swhash->hlist_mutex);
+		INIT_LIST_HEAD(&per_cpu(active_ctx_list, cpu));
+
+		INIT_LIST_HEAD(&per_cpu(pmu_sb_events.list, cpu));
+		raw_spin_lock_init(&per_cpu(pmu_sb_events.lock, cpu));
+
+#ifdef CONFIG_CGROUP_PERF
+		INIT_LIST_HEAD(&per_cpu(cgrp_cpuctx_list, cpu));
+#endif
+		INIT_LIST_HEAD(&per_cpu(sched_cb_list, cpu));
+	}
+}
+
+static void perf_swevent_init_cpu(unsigned int cpu)
+{
+	struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
+
+	mutex_lock(&swhash->hlist_mutex);
+	if (swhash->hlist_refcount > 0 && !swevent_hlist_deref(swhash)) {
+		struct swevent_hlist *hlist;
+
+		hlist = kzalloc_node(sizeof(*hlist), GFP_KERNEL, cpu_to_node(cpu));
+		WARN_ON(!hlist);
+		rcu_assign_pointer(swhash->swevent_hlist, hlist);
+	}
+	mutex_unlock(&swhash->hlist_mutex);
+}
+
+#if defined CONFIG_HOTPLUG_CPU || defined CONFIG_KEXEC_CORE
+static void __perf_event_exit_context(void *__info)
+{
+	struct perf_event_context *ctx = __info;
+	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct perf_event *event;
+
+	raw_spin_lock(&ctx->lock);
+	ctx_sched_out(ctx, cpuctx, EVENT_TIME);
+	list_for_each_entry(event, &ctx->event_list, event_entry)
+		__perf_remove_from_context(event, cpuctx, ctx, (void *)DETACH_GROUP);
+	raw_spin_unlock(&ctx->lock);
+}
+
+static void perf_event_exit_cpu_context(int cpu)
+{
+	struct perf_cpu_context *cpuctx;
+	struct perf_event_context *ctx;
+	struct pmu *pmu;
+
+	mutex_lock(&pmus_lock);
+	list_for_each_entry(pmu, &pmus, entry) {
+		cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+		ctx = &cpuctx->ctx;
+
+		mutex_lock(&ctx->mutex);
+		smp_call_function_single(cpu, __perf_event_exit_context, ctx, 1);
+		cpuctx->online = 0;
+		mutex_unlock(&ctx->mutex);
+	}
+	cpumask_clear_cpu(cpu, perf_online_mask);
+	mutex_unlock(&pmus_lock);
+}
+#else
+
+static void perf_event_exit_cpu_context(int cpu) { }
+
+#endif
+
+int perf_event_init_cpu(unsigned int cpu)
+{
+	struct perf_cpu_context *cpuctx;
+	struct perf_event_context *ctx;
+	struct pmu *pmu;
+
+	perf_swevent_init_cpu(cpu);
+
+	mutex_lock(&pmus_lock);
+	cpumask_set_cpu(cpu, perf_online_mask);
+	list_for_each_entry(pmu, &pmus, entry) {
+		cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+		ctx = &cpuctx->ctx;
+
+		mutex_lock(&ctx->mutex);
+		cpuctx->online = 1;
+		mutex_unlock(&ctx->mutex);
+	}
+	mutex_unlock(&pmus_lock);
+
+	return 0;
+}
+
+int perf_event_exit_cpu(unsigned int cpu)
+{
+	perf_event_exit_cpu_context(cpu);
+	return 0;
+}
+
+static int
+perf_reboot(struct notifier_block *notifier, unsigned long val, void *v)
+{
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		perf_event_exit_cpu(cpu);
+
+	return NOTIFY_OK;
+}
+
+/*
+ * Run the perf reboot notifier at the very last possible moment so that
+ * the generic watchdog code runs as long as possible.
+ */
+static struct notifier_block perf_reboot_notifier = {
+	.notifier_call = perf_reboot,
+	.priority = INT_MIN,
+};
+
+void __init perf_event_init(void)
+{
+	int ret;
+
+	idr_init(&pmu_idr);
+
+	perf_event_init_all_cpus();
+	init_srcu_struct(&pmus_srcu);
+	perf_pmu_register(&perf_swevent, "software", PERF_TYPE_SOFTWARE);
+	perf_pmu_register(&perf_cpu_clock, NULL, -1);
+	perf_pmu_register(&perf_task_clock, NULL, -1);
+	perf_tp_register();
+	perf_event_init_cpu(smp_processor_id());
+	register_reboot_notifier(&perf_reboot_notifier);
+
+	ret = init_hw_breakpoint();
+	WARN(ret, "hw_breakpoint initialization failed with: %d", ret);
+
+	perf_event_cache = KMEM_CACHE(perf_event, SLAB_PANIC);
+
+	/*
+	 * Build time assertion that we keep the data_head at the intended
+	 * location.  IOW, validation we got the __reserved[] size right.
+	 */
+	BUILD_BUG_ON((offsetof(struct perf_event_mmap_page, data_head))
+		     != 1024);
+}
+
+ssize_t perf_event_sysfs_show(struct device *dev, struct device_attribute *attr,
+			      char *page)
+{
+	struct perf_pmu_events_attr *pmu_attr =
+		container_of(attr, struct perf_pmu_events_attr, attr);
+
+	if (pmu_attr->event_str)
+		return sprintf(page, "%s\n", pmu_attr->event_str);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(perf_event_sysfs_show);
+
+static int __init perf_event_sysfs_init(void)
+{
+	struct pmu *pmu;
+	int ret;
+
+	mutex_lock(&pmus_lock);
+
+	ret = bus_register(&pmu_bus);
+	if (ret)
+		goto unlock;
+
+	list_for_each_entry(pmu, &pmus, entry) {
+		if (!pmu->name || pmu->type < 0)
+			continue;
+
+		ret = pmu_dev_alloc(pmu);
+		WARN(ret, "Failed to register pmu: %s, reason %d\n", pmu->name, ret);
+	}
+	pmu_bus_running = 1;
+	ret = 0;
+
+unlock:
+	mutex_unlock(&pmus_lock);
+
+	return ret;
+}
+device_initcall(perf_event_sysfs_init);
+
+#ifdef CONFIG_CGROUP_PERF
+static struct cgroup_subsys_state *
+perf_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+	struct perf_cgroup *jc;
+
+	jc = kzalloc(sizeof(*jc), GFP_KERNEL);
+	if (!jc)
+		return ERR_PTR(-ENOMEM);
+
+	jc->info = alloc_percpu(struct perf_cgroup_info);
+	if (!jc->info) {
+		kfree(jc);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	return &jc->css;
+}
+
+static void perf_cgroup_css_free(struct cgroup_subsys_state *css)
+{
+	struct perf_cgroup *jc = container_of(css, struct perf_cgroup, css);
+
+	free_percpu(jc->info);
+	kfree(jc);
+}
+
+static int perf_cgroup_css_online(struct cgroup_subsys_state *css)
+{
+	perf_event_cgroup(css->cgroup);
+	return 0;
+}
+
+static int __perf_cgroup_move(void *info)
+{
+	struct task_struct *task = info;
+	rcu_read_lock();
+	perf_cgroup_switch(task);
+	rcu_read_unlock();
+	return 0;
+}
+
+static void perf_cgroup_attach(struct cgroup_taskset *tset)
+{
+	struct task_struct *task;
+	struct cgroup_subsys_state *css;
+
+	cgroup_taskset_for_each(task, css, tset)
+		task_function_call(task, __perf_cgroup_move, task);
+}
+
+struct cgroup_subsys perf_event_cgrp_subsys = {
+	.css_alloc	= perf_cgroup_css_alloc,
+	.css_free	= perf_cgroup_css_free,
+	.css_online	= perf_cgroup_css_online,
+	.attach		= perf_cgroup_attach,
+	/*
+	 * Implicitly enable on dfl hierarchy so that perf events can
+	 * always be filtered by cgroup2 path as long as perf_event
+	 * controller is not mounted on a legacy hierarchy.
+	 */
+	.implicit_on_dfl = true,
+	.threaded	= true,
+};
+#endif /* CONFIG_CGROUP_PERF */
+
+DEFINE_STATIC_CALL_RET0(perf_snapshot_branch_stack, perf_snapshot_branch_stack_t);