1
linux/kernel/perf_event.c
Frederic Weisbecker 49f135ed02 perf: Comply with new rcu checks API
The software events hlist doesn't fully comply with the new
rcu checks api.

We need to consider three different sides that access the hlist:

- the hlist allocation/release side. This side happens when an
  events is created or released, accesses to the hlist are
  serialized under the cpuctx mutex.

- the events insertion/removal in the hlist. This side is always
  serialized against the above one. The hlist is always present
  during such operations. This side happens when a software event
  is scheduled in/out. The serialization that ensures the software
  event is really attached to the context is made under the
  ctx->lock.

- events triggering. This is the read side, it can happen
  concurrently with any update side.

This patch deals with them one by one and anticipates with the
separate rcu mem space patches in preparation.

This patch fixes various annoying rcu warnings.

Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
2010-05-20 10:40:37 +02:00

5771 lines
131 KiB
C

/*
* Performance events core code:
*
* Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
* Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
* Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
* Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
*
* For licensing details see kernel-base/COPYING
*/
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/file.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/hash.h>
#include <linux/sysfs.h>
#include <linux/dcache.h>
#include <linux/percpu.h>
#include <linux/ptrace.h>
#include <linux/vmstat.h>
#include <linux/vmalloc.h>
#include <linux/hardirq.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/perf_event.h>
#include <linux/ftrace_event.h>
#include <linux/hw_breakpoint.h>
#include <asm/irq_regs.h>
/*
* Each CPU has a list of per CPU events:
*/
static DEFINE_PER_CPU(struct perf_cpu_context, perf_cpu_context);
int perf_max_events __read_mostly = 1;
static int perf_reserved_percpu __read_mostly;
static int perf_overcommit __read_mostly = 1;
static atomic_t nr_events __read_mostly;
static atomic_t nr_mmap_events __read_mostly;
static atomic_t nr_comm_events __read_mostly;
static atomic_t nr_task_events __read_mostly;
/*
* 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 = 1;
int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */
/*
* max perf event sample rate
*/
int sysctl_perf_event_sample_rate __read_mostly = 100000;
static atomic64_t perf_event_id;
/*
* Lock for (sysadmin-configurable) event reservations:
*/
static DEFINE_SPINLOCK(perf_resource_lock);
/*
* Architecture provided APIs - weak aliases:
*/
extern __weak const struct pmu *hw_perf_event_init(struct perf_event *event)
{
return NULL;
}
void __weak hw_perf_disable(void) { barrier(); }
void __weak hw_perf_enable(void) { barrier(); }
void __weak perf_event_print_debug(void) { }
static DEFINE_PER_CPU(int, perf_disable_count);
void perf_disable(void)
{
if (!__get_cpu_var(perf_disable_count)++)
hw_perf_disable();
}
void perf_enable(void)
{
if (!--__get_cpu_var(perf_disable_count))
hw_perf_enable();
}
static void get_ctx(struct perf_event_context *ctx)
{
WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
}
static void free_ctx(struct rcu_head *head)
{
struct perf_event_context *ctx;
ctx = container_of(head, struct perf_event_context, rcu_head);
kfree(ctx);
}
static void put_ctx(struct perf_event_context *ctx)
{
if (atomic_dec_and_test(&ctx->refcount)) {
if (ctx->parent_ctx)
put_ctx(ctx->parent_ctx);
if (ctx->task)
put_task_struct(ctx->task);
call_rcu(&ctx->rcu_head, free_ctx);
}
}
static void unclone_ctx(struct perf_event_context *ctx)
{
if (ctx->parent_ctx) {
put_ctx(ctx->parent_ctx);
ctx->parent_ctx = NULL;
}
}
/*
* 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 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, unsigned long *flags)
{
struct perf_event_context *ctx;
rcu_read_lock();
retry:
ctx = rcu_dereference(task->perf_event_ctxp);
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_irqsave(&ctx->lock, *flags);
if (ctx != rcu_dereference(task->perf_event_ctxp)) {
raw_spin_unlock_irqrestore(&ctx->lock, *flags);
goto retry;
}
if (!atomic_inc_not_zero(&ctx->refcount)) {
raw_spin_unlock_irqrestore(&ctx->lock, *flags);
ctx = NULL;
}
}
rcu_read_unlock();
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)
{
struct perf_event_context *ctx;
unsigned long flags;
ctx = perf_lock_task_context(task, &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);
put_ctx(ctx);
}
static inline u64 perf_clock(void)
{
return cpu_clock(raw_smp_processor_id());
}
/*
* Update the record of the current time in a context.
*/
static void update_context_time(struct perf_event_context *ctx)
{
u64 now = perf_clock();
ctx->time += now - ctx->timestamp;
ctx->timestamp = now;
}
/*
* Update the total_time_enabled and total_time_running fields for a event.
*/
static void update_event_times(struct perf_event *event)
{
struct perf_event_context *ctx = event->ctx;
u64 run_end;
if (event->state < PERF_EVENT_STATE_INACTIVE ||
event->group_leader->state < PERF_EVENT_STATE_INACTIVE)
return;
if (ctx->is_active)
run_end = ctx->time;
else
run_end = event->tstamp_stopped;
event->total_time_enabled = run_end - event->tstamp_enabled;
if (event->state == PERF_EVENT_STATE_INACTIVE)
run_end = event->tstamp_stopped;
else
run_end = ctx->time;
event->total_time_running = run_end - event->tstamp_running;
}
/*
* Update total_time_enabled and total_time_running for all events in a group.
*/
static void update_group_times(struct perf_event *leader)
{
struct perf_event *event;
update_event_times(leader);
list_for_each_entry(event, &leader->sibling_list, group_entry)
update_event_times(event);
}
static struct list_head *
ctx_group_list(struct perf_event *event, struct perf_event_context *ctx)
{
if (event->attr.pinned)
return &ctx->pinned_groups;
else
return &ctx->flexible_groups;
}
/*
* Add a 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)
{
struct perf_event *group_leader = event->group_leader;
/*
* Depending on whether it is a standalone or sibling event,
* add it straight to the context's event list, or to the group
* leader's sibling list:
*/
if (group_leader == event) {
struct list_head *list;
if (is_software_event(event))
event->group_flags |= PERF_GROUP_SOFTWARE;
list = ctx_group_list(event, ctx);
list_add_tail(&event->group_entry, list);
} else {
if (group_leader->group_flags & PERF_GROUP_SOFTWARE &&
!is_software_event(event))
group_leader->group_flags &= ~PERF_GROUP_SOFTWARE;
list_add_tail(&event->group_entry, &group_leader->sibling_list);
group_leader->nr_siblings++;
}
list_add_rcu(&event->event_entry, &ctx->event_list);
ctx->nr_events++;
if (event->attr.inherit_stat)
ctx->nr_stat++;
}
/*
* Remove a 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)
{
if (list_empty(&event->group_entry))
return;
ctx->nr_events--;
if (event->attr.inherit_stat)
ctx->nr_stat--;
list_del_init(&event->group_entry);
list_del_rcu(&event->event_entry);
if (event->group_leader != event)
event->group_leader->nr_siblings--;
update_group_times(event);
/*
* 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)
event->state = PERF_EVENT_STATE_OFF;
}
static void
perf_destroy_group(struct perf_event *event, struct perf_event_context *ctx)
{
struct perf_event *sibling, *tmp;
/*
* If this was a group event with sibling events then
* upgrade the siblings to singleton events by adding them
* to the context list directly:
*/
list_for_each_entry_safe(sibling, tmp, &event->sibling_list, group_entry) {
struct list_head *list;
list = ctx_group_list(event, ctx);
list_move_tail(&sibling->group_entry, list);
sibling->group_leader = sibling;
/* Inherit group flags from the previous leader */
sibling->group_flags = event->group_flags;
}
}
static void
event_sched_out(struct perf_event *event,
struct perf_cpu_context *cpuctx,
struct perf_event_context *ctx)
{
if (event->state != PERF_EVENT_STATE_ACTIVE)
return;
event->state = PERF_EVENT_STATE_INACTIVE;
if (event->pending_disable) {
event->pending_disable = 0;
event->state = PERF_EVENT_STATE_OFF;
}
event->tstamp_stopped = ctx->time;
event->pmu->disable(event);
event->oncpu = -1;
if (!is_software_event(event))
cpuctx->active_oncpu--;
ctx->nr_active--;
if (event->attr.exclusive || !cpuctx->active_oncpu)
cpuctx->exclusive = 0;
}
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;
event_sched_out(group_event, cpuctx, ctx);
/*
* Schedule out siblings (if any):
*/
list_for_each_entry(event, &group_event->sibling_list, group_entry)
event_sched_out(event, cpuctx, ctx);
if (group_event->attr.exclusive)
cpuctx->exclusive = 0;
}
/*
* 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_event_remove_from_context(void *info)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_event *event = info;
struct perf_event_context *ctx = event->ctx;
/*
* 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.
*/
if (ctx->task && cpuctx->task_ctx != ctx)
return;
raw_spin_lock(&ctx->lock);
/*
* Protect the list operation against NMI by disabling the
* events on a global level.
*/
perf_disable();
event_sched_out(event, cpuctx, ctx);
list_del_event(event, ctx);
if (!ctx->task) {
/*
* Allow more per task events with respect to the
* reservation:
*/
cpuctx->max_pertask =
min(perf_max_events - ctx->nr_events,
perf_max_events - perf_reserved_percpu);
}
perf_enable();
raw_spin_unlock(&ctx->lock);
}
/*
* Remove the event from a task's (or a CPU's) list of events.
*
* Must be called with ctx->mutex held.
*
* CPU events are removed with a smp call. For task events we only
* call when the task is on a CPU.
*
* 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_event_remove_from_context(struct perf_event *event)
{
struct perf_event_context *ctx = event->ctx;
struct task_struct *task = ctx->task;
if (!task) {
/*
* Per cpu events are removed via an smp call and
* the removal is always successful.
*/
smp_call_function_single(event->cpu,
__perf_event_remove_from_context,
event, 1);
return;
}
retry:
task_oncpu_function_call(task, __perf_event_remove_from_context,
event);
raw_spin_lock_irq(&ctx->lock);
/*
* If the context is active we need to retry the smp call.
*/
if (ctx->nr_active && !list_empty(&event->group_entry)) {
raw_spin_unlock_irq(&ctx->lock);
goto retry;
}
/*
* The lock prevents that this context is scheduled in so we
* can remove the event safely, if the call above did not
* succeed.
*/
if (!list_empty(&event->group_entry))
list_del_event(event, ctx);
raw_spin_unlock_irq(&ctx->lock);
}
/*
* Cross CPU call to disable a performance event
*/
static void __perf_event_disable(void *info)
{
struct perf_event *event = info;
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_event_context *ctx = event->ctx;
/*
* If this is a per-task event, need to check whether this
* event's task is the current task on this cpu.
*/
if (ctx->task && cpuctx->task_ctx != ctx)
return;
raw_spin_lock(&ctx->lock);
/*
* If the event is on, turn it off.
* If it is in error state, leave it in error state.
*/
if (event->state >= PERF_EVENT_STATE_INACTIVE) {
update_context_time(ctx);
update_group_times(event);
if (event == event->group_leader)
group_sched_out(event, cpuctx, ctx);
else
event_sched_out(event, cpuctx, ctx);
event->state = PERF_EVENT_STATE_OFF;
}
raw_spin_unlock(&ctx->lock);
}
/*
* Disable a 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 satisifed 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 sync_child_event.
* When called from perf_pending_event 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.
*/
void perf_event_disable(struct perf_event *event)
{
struct perf_event_context *ctx = event->ctx;
struct task_struct *task = ctx->task;
if (!task) {
/*
* Disable the event on the cpu that it's on
*/
smp_call_function_single(event->cpu, __perf_event_disable,
event, 1);
return;
}
retry:
task_oncpu_function_call(task, __perf_event_disable, event);
raw_spin_lock_irq(&ctx->lock);
/*
* If the event is still active, we need to retry the cross-call.
*/
if (event->state == PERF_EVENT_STATE_ACTIVE) {
raw_spin_unlock_irq(&ctx->lock);
goto retry;
}
/*
* Since we have the lock this context can't be scheduled
* in, so we can change the state safely.
*/
if (event->state == PERF_EVENT_STATE_INACTIVE) {
update_group_times(event);
event->state = PERF_EVENT_STATE_OFF;
}
raw_spin_unlock_irq(&ctx->lock);
}
static int
event_sched_in(struct perf_event *event,
struct perf_cpu_context *cpuctx,
struct perf_event_context *ctx)
{
if (event->state <= PERF_EVENT_STATE_OFF)
return 0;
event->state = PERF_EVENT_STATE_ACTIVE;
event->oncpu = smp_processor_id();
/*
* The new state must be visible before we turn it on in the hardware:
*/
smp_wmb();
if (event->pmu->enable(event)) {
event->state = PERF_EVENT_STATE_INACTIVE;
event->oncpu = -1;
return -EAGAIN;
}
event->tstamp_running += ctx->time - event->tstamp_stopped;
if (!is_software_event(event))
cpuctx->active_oncpu++;
ctx->nr_active++;
if (event->attr.exclusive)
cpuctx->exclusive = 1;
return 0;
}
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;
const struct pmu *pmu = group_event->pmu;
bool txn = false;
int ret;
if (group_event->state == PERF_EVENT_STATE_OFF)
return 0;
/* Check if group transaction availabe */
if (pmu->start_txn)
txn = true;
if (txn)
pmu->start_txn(pmu);
if (event_sched_in(group_event, cpuctx, ctx))
return -EAGAIN;
/*
* Schedule in siblings as one group (if any):
*/
list_for_each_entry(event, &group_event->sibling_list, group_entry) {
if (event_sched_in(event, cpuctx, ctx)) {
partial_group = event;
goto group_error;
}
}
if (!txn)
return 0;
ret = pmu->commit_txn(pmu);
if (!ret) {
pmu->cancel_txn(pmu);
return 0;
}
group_error:
if (txn)
pmu->cancel_txn(pmu);
/*
* Groups can be scheduled in as one unit only, so undo any
* partial group before returning:
*/
list_for_each_entry(event, &group_event->sibling_list, group_entry) {
if (event == partial_group)
break;
event_sched_out(event, cpuctx, ctx);
}
event_sched_out(group_event, cpuctx, ctx);
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_flags & PERF_GROUP_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 && cpuctx->active_oncpu)
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);
event->tstamp_enabled = ctx->time;
event->tstamp_running = ctx->time;
event->tstamp_stopped = ctx->time;
}
/*
* Cross CPU call to install and enable a performance event
*
* Must be called with ctx->mutex held
*/
static void __perf_install_in_context(void *info)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_event *event = info;
struct perf_event_context *ctx = event->ctx;
struct perf_event *leader = event->group_leader;
int err;
/*
* 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.
* Or possibly this is the right context but it isn't
* on this cpu because it had no events.
*/
if (ctx->task && cpuctx->task_ctx != ctx) {
if (cpuctx->task_ctx || ctx->task != current)
return;
cpuctx->task_ctx = ctx;
}
raw_spin_lock(&ctx->lock);
ctx->is_active = 1;
update_context_time(ctx);
/*
* Protect the list operation against NMI by disabling the
* events on a global level. NOP for non NMI based events.
*/
perf_disable();
add_event_to_ctx(event, ctx);
if (event->cpu != -1 && event->cpu != smp_processor_id())
goto unlock;
/*
* Don't put the event on if it is disabled or if
* it is in a group and the group isn't on.
*/
if (event->state != PERF_EVENT_STATE_INACTIVE ||
(leader != event && leader->state != PERF_EVENT_STATE_ACTIVE))
goto unlock;
/*
* An exclusive event can't go on if there are already active
* hardware events, and no hardware event can go on if there
* is already an exclusive event on.
*/
if (!group_can_go_on(event, cpuctx, 1))
err = -EEXIST;
else
err = event_sched_in(event, cpuctx, ctx);
if (err) {
/*
* This event couldn't go on. If it is in a group
* then we have to pull the whole group off.
* If the event group is pinned then put it in error state.
*/
if (leader != event)
group_sched_out(leader, cpuctx, ctx);
if (leader->attr.pinned) {
update_group_times(leader);
leader->state = PERF_EVENT_STATE_ERROR;
}
}
if (!err && !ctx->task && cpuctx->max_pertask)
cpuctx->max_pertask--;
unlock:
perf_enable();
raw_spin_unlock(&ctx->lock);
}
/*
* Attach a performance event to a context
*
* First we add the event to the list with the hardware enable bit
* in event->hw_config cleared.
*
* If the event is attached to a task which is on a CPU we use a smp
* call to enable it in the task context. The task might have been
* scheduled away, but we check this in the smp call again.
*
* Must be called with ctx->mutex held.
*/
static void
perf_install_in_context(struct perf_event_context *ctx,
struct perf_event *event,
int cpu)
{
struct task_struct *task = ctx->task;
if (!task) {
/*
* Per cpu events are installed via an smp call and
* the install is always successful.
*/
smp_call_function_single(cpu, __perf_install_in_context,
event, 1);
return;
}
retry:
task_oncpu_function_call(task, __perf_install_in_context,
event);
raw_spin_lock_irq(&ctx->lock);
/*
* we need to retry the smp call.
*/
if (ctx->is_active && list_empty(&event->group_entry)) {
raw_spin_unlock_irq(&ctx->lock);
goto retry;
}
/*
* The lock prevents that this context is scheduled in so we
* can add the event safely, if it the call above did not
* succeed.
*/
if (list_empty(&event->group_entry))
add_event_to_ctx(event, ctx);
raw_spin_unlock_irq(&ctx->lock);
}
/*
* Put a event into inactive state and update time fields.
* Enabling the leader of a group effectively enables all
* the group members that aren't explicitly disabled, so we
* have to update their ->tstamp_enabled also.
* Note: this works for group members as well as group leaders
* since the non-leader members' sibling_lists will be empty.
*/
static void __perf_event_mark_enabled(struct perf_event *event,
struct perf_event_context *ctx)
{
struct perf_event *sub;
event->state = PERF_EVENT_STATE_INACTIVE;
event->tstamp_enabled = ctx->time - event->total_time_enabled;
list_for_each_entry(sub, &event->sibling_list, group_entry)
if (sub->state >= PERF_EVENT_STATE_INACTIVE)
sub->tstamp_enabled =
ctx->time - sub->total_time_enabled;
}
/*
* Cross CPU call to enable a performance event
*/
static void __perf_event_enable(void *info)
{
struct perf_event *event = info;
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_event_context *ctx = event->ctx;
struct perf_event *leader = event->group_leader;
int err;
/*
* If this is a per-task event, need to check whether this
* event's task is the current task on this cpu.
*/
if (ctx->task && cpuctx->task_ctx != ctx) {
if (cpuctx->task_ctx || ctx->task != current)
return;
cpuctx->task_ctx = ctx;
}
raw_spin_lock(&ctx->lock);
ctx->is_active = 1;
update_context_time(ctx);
if (event->state >= PERF_EVENT_STATE_INACTIVE)
goto unlock;
__perf_event_mark_enabled(event, ctx);
if (event->cpu != -1 && event->cpu != smp_processor_id())
goto unlock;
/*
* 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)
goto unlock;
if (!group_can_go_on(event, cpuctx, 1)) {
err = -EEXIST;
} else {
perf_disable();
if (event == leader)
err = group_sched_in(event, cpuctx, ctx);
else
err = event_sched_in(event, cpuctx, ctx);
perf_enable();
}
if (err) {
/*
* If this event can't go on and it's part of a
* group, then the whole group has to come off.
*/
if (leader != event)
group_sched_out(leader, cpuctx, ctx);
if (leader->attr.pinned) {
update_group_times(leader);
leader->state = PERF_EVENT_STATE_ERROR;
}
}
unlock:
raw_spin_unlock(&ctx->lock);
}
/*
* Enable a 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.
*/
void perf_event_enable(struct perf_event *event)
{
struct perf_event_context *ctx = event->ctx;
struct task_struct *task = ctx->task;
if (!task) {
/*
* Enable the event on the cpu that it's on
*/
smp_call_function_single(event->cpu, __perf_event_enable,
event, 1);
return;
}
raw_spin_lock_irq(&ctx->lock);
if (event->state >= PERF_EVENT_STATE_INACTIVE)
goto out;
/*
* 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)
event->state = PERF_EVENT_STATE_OFF;
retry:
raw_spin_unlock_irq(&ctx->lock);
task_oncpu_function_call(task, __perf_event_enable, event);
raw_spin_lock_irq(&ctx->lock);
/*
* If the context is active and the event is still off,
* we need to retry the cross-call.
*/
if (ctx->is_active && event->state == PERF_EVENT_STATE_OFF)
goto retry;
/*
* Since we have the lock this context can't be scheduled
* in, so we can change the state safely.
*/
if (event->state == PERF_EVENT_STATE_OFF)
__perf_event_mark_enabled(event, ctx);
out:
raw_spin_unlock_irq(&ctx->lock);
}
static int perf_event_refresh(struct perf_event *event, int refresh)
{
/*
* not supported on inherited events
*/
if (event->attr.inherit)
return -EINVAL;
atomic_add(refresh, &event->event_limit);
perf_event_enable(event);
return 0;
}
enum event_type_t {
EVENT_FLEXIBLE = 0x1,
EVENT_PINNED = 0x2,
EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
};
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;
raw_spin_lock(&ctx->lock);
ctx->is_active = 0;
if (likely(!ctx->nr_events))
goto out;
update_context_time(ctx);
perf_disable();
if (!ctx->nr_active)
goto out_enable;
if (event_type & EVENT_PINNED)
list_for_each_entry(event, &ctx->pinned_groups, group_entry)
group_sched_out(event, cpuctx, ctx);
if (event_type & EVENT_FLEXIBLE)
list_for_each_entry(event, &ctx->flexible_groups, group_entry)
group_sched_out(event, cpuctx, ctx);
out_enable:
perf_enable();
out:
raw_spin_unlock(&ctx->lock);
}
/*
* Test whether two contexts are equivalent, i.e. whether they
* have both been cloned from the same version of the same context
* and they both have the same number of enabled events.
* If the number of enabled events is the same, then the set
* of enabled events should be the same, because these are both
* inherited contexts, therefore we can't access individual events
* in them directly with an fd; we can only enable/disable all
* events via prctl, or enable/disable all events in a family
* via ioctl, which will have the same effect on both contexts.
*/
static int context_equiv(struct perf_event_context *ctx1,
struct perf_event_context *ctx2)
{
return ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx
&& ctx1->parent_gen == ctx2->parent_gen
&& !ctx1->pin_count && !ctx2->pin_count;
}
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.
*/
switch (event->state) {
case PERF_EVENT_STATE_ACTIVE:
event->pmu->read(event);
/* fall-through */
case PERF_EVENT_STATE_INACTIVE:
update_event_times(event);
break;
default:
break;
}
/*
* In order to keep per-task stats reliable we need to flip the event
* values when we flip the contexts.
*/
value = atomic64_read(&next_event->count);
value = atomic64_xchg(&event->count, value);
atomic64_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);
}
#define list_next_entry(pos, member) \
list_entry(pos->member.next, typeof(*pos), member)
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);
}
}
/*
* 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)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_event_context *ctx = task->perf_event_ctxp;
struct perf_event_context *next_ctx;
struct perf_event_context *parent;
int do_switch = 1;
perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, NULL, 0);
if (likely(!ctx || !cpuctx->task_ctx))
return;
rcu_read_lock();
parent = rcu_dereference(ctx->parent_ctx);
next_ctx = next->perf_event_ctxp;
if (parent && next_ctx &&
rcu_dereference(next_ctx->parent_ctx) == 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)) {
/*
* XXX do we need a memory barrier of sorts
* wrt to rcu_dereference() of perf_event_ctxp
*/
task->perf_event_ctxp = next_ctx;
next->perf_event_ctxp = ctx;
ctx->task = next;
next_ctx->task = task;
do_switch = 0;
perf_event_sync_stat(ctx, next_ctx);
}
raw_spin_unlock(&next_ctx->lock);
raw_spin_unlock(&ctx->lock);
}
rcu_read_unlock();
if (do_switch) {
ctx_sched_out(ctx, cpuctx, EVENT_ALL);
cpuctx->task_ctx = NULL;
}
}
static void task_ctx_sched_out(struct perf_event_context *ctx,
enum event_type_t event_type)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
if (!cpuctx->task_ctx)
return;
if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
return;
ctx_sched_out(ctx, cpuctx, event_type);
cpuctx->task_ctx = NULL;
}
/*
* Called with IRQs disabled
*/
static void __perf_event_task_sched_out(struct perf_event_context *ctx)
{
task_ctx_sched_out(ctx, EVENT_ALL);
}
/*
* 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 void
ctx_pinned_sched_in(struct perf_event_context *ctx,
struct perf_cpu_context *cpuctx)
{
struct perf_event *event;
list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
if (event->state <= PERF_EVENT_STATE_OFF)
continue;
if (event->cpu != -1 && event->cpu != smp_processor_id())
continue;
if (group_can_go_on(event, cpuctx, 1))
group_sched_in(event, cpuctx, ctx);
/*
* If this pinned group hasn't been scheduled,
* put it in error state.
*/
if (event->state == PERF_EVENT_STATE_INACTIVE) {
update_group_times(event);
event->state = PERF_EVENT_STATE_ERROR;
}
}
}
static void
ctx_flexible_sched_in(struct perf_event_context *ctx,
struct perf_cpu_context *cpuctx)
{
struct perf_event *event;
int can_add_hw = 1;
list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
/* Ignore events in OFF or ERROR state */
if (event->state <= PERF_EVENT_STATE_OFF)
continue;
/*
* Listen to the 'cpu' scheduling filter constraint
* of events:
*/
if (event->cpu != -1 && event->cpu != smp_processor_id())
continue;
if (group_can_go_on(event, cpuctx, can_add_hw))
if (group_sched_in(event, cpuctx, ctx))
can_add_hw = 0;
}
}
static void
ctx_sched_in(struct perf_event_context *ctx,
struct perf_cpu_context *cpuctx,
enum event_type_t event_type)
{
raw_spin_lock(&ctx->lock);
ctx->is_active = 1;
if (likely(!ctx->nr_events))
goto out;
ctx->timestamp = perf_clock();
perf_disable();
/*
* First go through the list and put on any pinned groups
* in order to give them the best chance of going on.
*/
if (event_type & EVENT_PINNED)
ctx_pinned_sched_in(ctx, cpuctx);
/* Then walk through the lower prio flexible groups */
if (event_type & EVENT_FLEXIBLE)
ctx_flexible_sched_in(ctx, cpuctx);
perf_enable();
out:
raw_spin_unlock(&ctx->lock);
}
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 task_ctx_sched_in(struct task_struct *task,
enum event_type_t event_type)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_event_context *ctx = task->perf_event_ctxp;
if (likely(!ctx))
return;
if (cpuctx->task_ctx == ctx)
return;
ctx_sched_in(ctx, cpuctx, event_type);
cpuctx->task_ctx = 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 *task)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_event_context *ctx = task->perf_event_ctxp;
if (likely(!ctx))
return;
if (cpuctx->task_ctx == ctx)
return;
perf_disable();
/*
* We want to keep the following priority order:
* cpu pinned (that don't need to move), task pinned,
* cpu flexible, task flexible.
*/
cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
ctx_sched_in(ctx, cpuctx, EVENT_PINNED);
cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE);
cpuctx->task_ctx = ctx;
perf_enable();
}
#define MAX_INTERRUPTS (~0ULL)
static void perf_log_throttle(struct perf_event *event, int enable);
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;
}
return div64_u64(dividend, divisor);
}
static void perf_event_stop(struct perf_event *event)
{
if (!event->pmu->stop)
return event->pmu->disable(event);
return event->pmu->stop(event);
}
static int perf_event_start(struct perf_event *event)
{
if (!event->pmu->start)
return event->pmu->enable(event);
return event->pmu->start(event);
}
static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count)
{
struct hw_perf_event *hwc = &event->hw;
u64 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 (atomic64_read(&hwc->period_left) > 8*sample_period) {
perf_disable();
perf_event_stop(event);
atomic64_set(&hwc->period_left, 0);
perf_event_start(event);
perf_enable();
}
}
static void perf_ctx_adjust_freq(struct perf_event_context *ctx)
{
struct perf_event *event;
struct hw_perf_event *hwc;
u64 interrupts, now;
s64 delta;
raw_spin_lock(&ctx->lock);
list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
if (event->state != PERF_EVENT_STATE_ACTIVE)
continue;
if (event->cpu != -1 && event->cpu != smp_processor_id())
continue;
hwc = &event->hw;
interrupts = hwc->interrupts;
hwc->interrupts = 0;
/*
* unthrottle events on the tick
*/
if (interrupts == MAX_INTERRUPTS) {
perf_log_throttle(event, 1);
perf_disable();
event->pmu->unthrottle(event);
perf_enable();
}
if (!event->attr.freq || !event->attr.sample_freq)
continue;
perf_disable();
event->pmu->read(event);
now = atomic64_read(&event->count);
delta = now - hwc->freq_count_stamp;
hwc->freq_count_stamp = now;
if (delta > 0)
perf_adjust_period(event, TICK_NSEC, delta);
perf_enable();
}
raw_spin_unlock(&ctx->lock);
}
/*
* Round-robin a context's events:
*/
static void rotate_ctx(struct perf_event_context *ctx)
{
raw_spin_lock(&ctx->lock);
/* Rotate the first entry last of non-pinned groups */
list_rotate_left(&ctx->flexible_groups);
raw_spin_unlock(&ctx->lock);
}
void perf_event_task_tick(struct task_struct *curr)
{
struct perf_cpu_context *cpuctx;
struct perf_event_context *ctx;
int rotate = 0;
if (!atomic_read(&nr_events))
return;
cpuctx = &__get_cpu_var(perf_cpu_context);
if (cpuctx->ctx.nr_events &&
cpuctx->ctx.nr_events != cpuctx->ctx.nr_active)
rotate = 1;
ctx = curr->perf_event_ctxp;
if (ctx && ctx->nr_events && ctx->nr_events != ctx->nr_active)
rotate = 1;
perf_ctx_adjust_freq(&cpuctx->ctx);
if (ctx)
perf_ctx_adjust_freq(ctx);
if (!rotate)
return;
perf_disable();
cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
if (ctx)
task_ctx_sched_out(ctx, EVENT_FLEXIBLE);
rotate_ctx(&cpuctx->ctx);
if (ctx)
rotate_ctx(ctx);
cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
if (ctx)
task_ctx_sched_in(curr, EVENT_FLEXIBLE);
perf_enable();
}
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_mark_enabled(event, ctx);
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(struct task_struct *task)
{
struct perf_event_context *ctx;
struct perf_event *event;
unsigned long flags;
int enabled = 0;
int ret;
local_irq_save(flags);
ctx = task->perf_event_ctxp;
if (!ctx || !ctx->nr_events)
goto out;
__perf_event_task_sched_out(ctx);
raw_spin_lock(&ctx->lock);
list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
ret = event_enable_on_exec(event, ctx);
if (ret)
enabled = 1;
}
list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
ret = event_enable_on_exec(event, ctx);
if (ret)
enabled = 1;
}
/*
* Unclone this context if we enabled any event.
*/
if (enabled)
unclone_ctx(ctx);
raw_spin_unlock(&ctx->lock);
perf_event_task_sched_in(task);
out:
local_irq_restore(flags);
}
/*
* Cross CPU call to read the hardware event
*/
static void __perf_event_read(void *info)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_event *event = info;
struct perf_event_context *ctx = event->ctx;
/*
* 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);
update_context_time(ctx);
update_event_times(event);
raw_spin_unlock(&ctx->lock);
event->pmu->read(event);
}
static u64 perf_event_read(struct perf_event *event)
{
/*
* If event is enabled and currently active on a CPU, update the
* value in the event structure:
*/
if (event->state == PERF_EVENT_STATE_ACTIVE) {
smp_call_function_single(event->oncpu,
__perf_event_read, event, 1);
} else if (event->state == PERF_EVENT_STATE_INACTIVE) {
struct perf_event_context *ctx = event->ctx;
unsigned long flags;
raw_spin_lock_irqsave(&ctx->lock, flags);
update_context_time(ctx);
update_event_times(event);
raw_spin_unlock_irqrestore(&ctx->lock, flags);
}
return atomic64_read(&event->count);
}
/*
* Initialize the perf_event context in a task_struct:
*/
static void
__perf_event_init_context(struct perf_event_context *ctx,
struct task_struct *task)
{
raw_spin_lock_init(&ctx->lock);
mutex_init(&ctx->mutex);
INIT_LIST_HEAD(&ctx->pinned_groups);
INIT_LIST_HEAD(&ctx->flexible_groups);
INIT_LIST_HEAD(&ctx->event_list);
atomic_set(&ctx->refcount, 1);
ctx->task = task;
}
static struct perf_event_context *find_get_context(pid_t pid, int cpu)
{
struct perf_event_context *ctx;
struct perf_cpu_context *cpuctx;
struct task_struct *task;
unsigned long flags;
int err;
if (pid == -1 && cpu != -1) {
/* Must be root to operate on a CPU event: */
if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
return ERR_PTR(-EACCES);
if (cpu < 0 || cpu >= nr_cpumask_bits)
return ERR_PTR(-EINVAL);
/*
* We could be clever and allow to attach a event to an
* offline CPU and activate it when the CPU comes up, but
* that's for later.
*/
if (!cpu_online(cpu))
return ERR_PTR(-ENODEV);
cpuctx = &per_cpu(perf_cpu_context, cpu);
ctx = &cpuctx->ctx;
get_ctx(ctx);
return ctx;
}
rcu_read_lock();
if (!pid)
task = current;
else
task = find_task_by_vpid(pid);
if (task)
get_task_struct(task);
rcu_read_unlock();
if (!task)
return ERR_PTR(-ESRCH);
/*
* Can't attach events to a dying task.
*/
err = -ESRCH;
if (task->flags & PF_EXITING)
goto errout;
/* Reuse ptrace permission checks for now. */
err = -EACCES;
if (!ptrace_may_access(task, PTRACE_MODE_READ))
goto errout;
retry:
ctx = perf_lock_task_context(task, &flags);
if (ctx) {
unclone_ctx(ctx);
raw_spin_unlock_irqrestore(&ctx->lock, flags);
}
if (!ctx) {
ctx = kzalloc(sizeof(struct perf_event_context), GFP_KERNEL);
err = -ENOMEM;
if (!ctx)
goto errout;
__perf_event_init_context(ctx, task);
get_ctx(ctx);
if (cmpxchg(&task->perf_event_ctxp, NULL, ctx)) {
/*
* We raced with some other task; use
* the context they set.
*/
kfree(ctx);
goto retry;
}
get_task_struct(task);
}
put_task_struct(task);
return ctx;
errout:
put_task_struct(task);
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);
kfree(event);
}
static void perf_pending_sync(struct perf_event *event);
static void free_event(struct perf_event *event)
{
perf_pending_sync(event);
if (!event->parent) {
atomic_dec(&nr_events);
if (event->attr.mmap)
atomic_dec(&nr_mmap_events);
if (event->attr.comm)
atomic_dec(&nr_comm_events);
if (event->attr.task)
atomic_dec(&nr_task_events);
}
if (event->output) {
fput(event->output->filp);
event->output = NULL;
}
if (event->destroy)
event->destroy(event);
put_ctx(event->ctx);
call_rcu(&event->rcu_head, free_event_rcu);
}
int perf_event_release_kernel(struct perf_event *event)
{
struct perf_event_context *ctx = event->ctx;
/*
* Remove from the PMU, can't get re-enabled since we got
* here because the last ref went.
*/
perf_event_disable(event);
WARN_ON_ONCE(ctx->parent_ctx);
/*
* There are two ways this annotation is useful:
*
* 1) there is a lock recursion from perf_event_exit_task
* see the comment there.
*
* 2) there is a lock-inversion with mmap_sem through
* perf_event_read_group(), which takes faults while
* holding ctx->mutex, however this is called after
* the last filedesc died, so there is no possibility
* to trigger the AB-BA case.
*/
mutex_lock_nested(&ctx->mutex, SINGLE_DEPTH_NESTING);
raw_spin_lock_irq(&ctx->lock);
list_del_event(event, ctx);
perf_destroy_group(event, ctx);
raw_spin_unlock_irq(&ctx->lock);
mutex_unlock(&ctx->mutex);
mutex_lock(&event->owner->perf_event_mutex);
list_del_init(&event->owner_entry);
mutex_unlock(&event->owner->perf_event_mutex);
put_task_struct(event->owner);
free_event(event);
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)
{
struct perf_event *event = file->private_data;
file->private_data = NULL;
return perf_event_release_kernel(event);
}
static int perf_event_read_size(struct perf_event *event)
{
int entry = sizeof(u64); /* value */
int size = 0;
int nr = 1;
if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
size += sizeof(u64);
if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
size += sizeof(u64);
if (event->attr.read_format & PERF_FORMAT_ID)
entry += sizeof(u64);
if (event->attr.read_format & PERF_FORMAT_GROUP) {
nr += event->group_leader->nr_siblings;
size += sizeof(u64);
}
size += entry * nr;
return size;
}
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);
total += perf_event_read(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) {
total += perf_event_read(child);
*enabled += child->total_time_enabled;
*running += child->total_time_running;
}
mutex_unlock(&event->child_mutex);
return total;
}
EXPORT_SYMBOL_GPL(perf_event_read_value);
static int perf_event_read_group(struct perf_event *event,
u64 read_format, char __user *buf)
{
struct perf_event *leader = event->group_leader, *sub;
int n = 0, size = 0, ret = -EFAULT;
struct perf_event_context *ctx = leader->ctx;
u64 values[5];
u64 count, enabled, running;
mutex_lock(&ctx->mutex);
count = perf_event_read_value(leader, &enabled, &running);
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;
values[n++] = count;
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(leader);
size = n * sizeof(u64);
if (copy_to_user(buf, values, size))
goto unlock;
ret = size;
list_for_each_entry(sub, &leader->sibling_list, group_entry) {
n = 0;
values[n++] = perf_event_read_value(sub, &enabled, &running);
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(sub);
size = n * sizeof(u64);
if (copy_to_user(buf + ret, values, size)) {
ret = -EFAULT;
goto unlock;
}
ret += size;
}
unlock:
mutex_unlock(&ctx->mutex);
return ret;
}
static int perf_event_read_one(struct perf_event *event,
u64 read_format, char __user *buf)
{
u64 enabled, running;
u64 values[4];
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 (copy_to_user(buf, values, n * sizeof(u64)))
return -EFAULT;
return n * sizeof(u64);
}
/*
* Read the performance event - simple non blocking version for now
*/
static ssize_t
perf_read_hw(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 a 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 < perf_event_read_size(event))
return -ENOSPC;
WARN_ON_ONCE(event->ctx->parent_ctx);
if (read_format & PERF_FORMAT_GROUP)
ret = perf_event_read_group(event, read_format, buf);
else
ret = perf_event_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;
return perf_read_hw(event, buf, count);
}
static unsigned int perf_poll(struct file *file, poll_table *wait)
{
struct perf_event *event = file->private_data;
struct perf_mmap_data *data;
unsigned int events = POLL_HUP;
rcu_read_lock();
data = rcu_dereference(event->data);
if (data)
events = atomic_xchg(&data->poll, 0);
rcu_read_unlock();
poll_wait(file, &event->waitq, wait);
return events;
}
static void perf_event_reset(struct perf_event *event)
{
(void)perf_event_read(event);
atomic64_set(&event->count, 0);
perf_event_update_userpage(event);
}
/*
* Holding the top-level event's child_mutex means that any
* descendant process that has inherited this event will block
* in sync_child_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;
WARN_ON_ONCE(ctx->parent_ctx);
mutex_lock(&ctx->mutex);
event = event->group_leader;
perf_event_for_each_child(event, func);
func(event);
list_for_each_entry(sibling, &event->sibling_list, group_entry)
perf_event_for_each_child(event, func);
mutex_unlock(&ctx->mutex);
}
static int perf_event_period(struct perf_event *event, u64 __user *arg)
{
struct perf_event_context *ctx = event->ctx;
unsigned long size;
int ret = 0;
u64 value;
if (!event->attr.sample_period)
return -EINVAL;
size = copy_from_user(&value, arg, sizeof(value));
if (size != sizeof(value))
return -EFAULT;
if (!value)
return -EINVAL;
raw_spin_lock_irq(&ctx->lock);
if (event->attr.freq) {
if (value > sysctl_perf_event_sample_rate) {
ret = -EINVAL;
goto unlock;
}
event->attr.sample_freq = value;
} else {
event->attr.sample_period = value;
event->hw.sample_period = value;
}
unlock:
raw_spin_unlock_irq(&ctx->lock);
return ret;
}
static int perf_event_set_output(struct perf_event *event, int output_fd);
static int perf_event_set_filter(struct perf_event *event, void __user *arg);
static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct perf_event *event = file->private_data;
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:
return perf_event_period(event, (u64 __user *)arg);
case PERF_EVENT_IOC_SET_OUTPUT:
return perf_event_set_output(event, arg);
case PERF_EVENT_IOC_SET_FILTER:
return perf_event_set_filter(event, (void __user *)arg);
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;
}
int perf_event_task_enable(void)
{
struct perf_event *event;
mutex_lock(&current->perf_event_mutex);
list_for_each_entry(event, &current->perf_event_list, owner_entry)
perf_event_for_each_child(event, perf_event_enable);
mutex_unlock(&current->perf_event_mutex);
return 0;
}
int perf_event_task_disable(void)
{
struct perf_event *event;
mutex_lock(&current->perf_event_mutex);
list_for_each_entry(event, &current->perf_event_list, owner_entry)
perf_event_for_each_child(event, perf_event_disable);
mutex_unlock(&current->perf_event_mutex);
return 0;
}
#ifndef PERF_EVENT_INDEX_OFFSET
# define PERF_EVENT_INDEX_OFFSET 0
#endif
static int perf_event_index(struct perf_event *event)
{
if (event->state != PERF_EVENT_STATE_ACTIVE)
return 0;
return event->hw.idx + 1 - PERF_EVENT_INDEX_OFFSET;
}
/*
* 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_mmap_data *data;
rcu_read_lock();
data = rcu_dereference(event->data);
if (!data)
goto unlock;
userpg = data->user_page;
/*
* Disable preemption so as to not let the corresponding user-space
* spin too long if we get preempted.
*/
preempt_disable();
++userpg->lock;
barrier();
userpg->index = perf_event_index(event);
userpg->offset = atomic64_read(&event->count);
if (event->state == PERF_EVENT_STATE_ACTIVE)
userpg->offset -= atomic64_read(&event->hw.prev_count);
userpg->time_enabled = event->total_time_enabled +
atomic64_read(&event->child_total_time_enabled);
userpg->time_running = event->total_time_running +
atomic64_read(&event->child_total_time_running);
barrier();
++userpg->lock;
preempt_enable();
unlock:
rcu_read_unlock();
}
static unsigned long perf_data_size(struct perf_mmap_data *data)
{
return data->nr_pages << (PAGE_SHIFT + data->data_order);
}
#ifndef CONFIG_PERF_USE_VMALLOC
/*
* Back perf_mmap() with regular GFP_KERNEL-0 pages.
*/
static struct page *
perf_mmap_to_page(struct perf_mmap_data *data, unsigned long pgoff)
{
if (pgoff > data->nr_pages)
return NULL;
if (pgoff == 0)
return virt_to_page(data->user_page);
return virt_to_page(data->data_pages[pgoff - 1]);
}
static struct perf_mmap_data *
perf_mmap_data_alloc(struct perf_event *event, int nr_pages)
{
struct perf_mmap_data *data;
unsigned long size;
int i;
WARN_ON(atomic_read(&event->mmap_count));
size = sizeof(struct perf_mmap_data);
size += nr_pages * sizeof(void *);
data = kzalloc(size, GFP_KERNEL);
if (!data)
goto fail;
data->user_page = (void *)get_zeroed_page(GFP_KERNEL);
if (!data->user_page)
goto fail_user_page;
for (i = 0; i < nr_pages; i++) {
data->data_pages[i] = (void *)get_zeroed_page(GFP_KERNEL);
if (!data->data_pages[i])
goto fail_data_pages;
}
data->data_order = 0;
data->nr_pages = nr_pages;
return data;
fail_data_pages:
for (i--; i >= 0; i--)
free_page((unsigned long)data->data_pages[i]);
free_page((unsigned long)data->user_page);
fail_user_page:
kfree(data);
fail:
return NULL;
}
static void perf_mmap_free_page(unsigned long addr)
{
struct page *page = virt_to_page((void *)addr);
page->mapping = NULL;
__free_page(page);
}
static void perf_mmap_data_free(struct perf_mmap_data *data)
{
int i;
perf_mmap_free_page((unsigned long)data->user_page);
for (i = 0; i < data->nr_pages; i++)
perf_mmap_free_page((unsigned long)data->data_pages[i]);
kfree(data);
}
#else
/*
* Back perf_mmap() with vmalloc memory.
*
* Required for architectures that have d-cache aliasing issues.
*/
static struct page *
perf_mmap_to_page(struct perf_mmap_data *data, unsigned long pgoff)
{
if (pgoff > (1UL << data->data_order))
return NULL;
return vmalloc_to_page((void *)data->user_page + pgoff * PAGE_SIZE);
}
static void perf_mmap_unmark_page(void *addr)
{
struct page *page = vmalloc_to_page(addr);
page->mapping = NULL;
}
static void perf_mmap_data_free_work(struct work_struct *work)
{
struct perf_mmap_data *data;
void *base;
int i, nr;
data = container_of(work, struct perf_mmap_data, work);
nr = 1 << data->data_order;
base = data->user_page;
for (i = 0; i < nr + 1; i++)
perf_mmap_unmark_page(base + (i * PAGE_SIZE));
vfree(base);
kfree(data);
}
static void perf_mmap_data_free(struct perf_mmap_data *data)
{
schedule_work(&data->work);
}
static struct perf_mmap_data *
perf_mmap_data_alloc(struct perf_event *event, int nr_pages)
{
struct perf_mmap_data *data;
unsigned long size;
void *all_buf;
WARN_ON(atomic_read(&event->mmap_count));
size = sizeof(struct perf_mmap_data);
size += sizeof(void *);
data = kzalloc(size, GFP_KERNEL);
if (!data)
goto fail;
INIT_WORK(&data->work, perf_mmap_data_free_work);
all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
if (!all_buf)
goto fail_all_buf;
data->user_page = all_buf;
data->data_pages[0] = all_buf + PAGE_SIZE;
data->data_order = ilog2(nr_pages);
data->nr_pages = 1;
return data;
fail_all_buf:
kfree(data);
fail:
return NULL;
}
#endif
static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct perf_event *event = vma->vm_file->private_data;
struct perf_mmap_data *data;
int ret = VM_FAULT_SIGBUS;
if (vmf->flags & FAULT_FLAG_MKWRITE) {
if (vmf->pgoff == 0)
ret = 0;
return ret;
}
rcu_read_lock();
data = rcu_dereference(event->data);
if (!data)
goto unlock;
if (vmf->pgoff && (vmf->flags & FAULT_FLAG_WRITE))
goto unlock;
vmf->page = perf_mmap_to_page(data, vmf->pgoff);
if (!vmf->page)
goto unlock;
get_page(vmf->page);
vmf->page->mapping = vma->vm_file->f_mapping;
vmf->page->index = vmf->pgoff;
ret = 0;
unlock:
rcu_read_unlock();
return ret;
}
static void
perf_mmap_data_init(struct perf_event *event, struct perf_mmap_data *data)
{
long max_size = perf_data_size(data);
atomic_set(&data->lock, -1);
if (event->attr.watermark) {
data->watermark = min_t(long, max_size,
event->attr.wakeup_watermark);
}
if (!data->watermark)
data->watermark = max_size / 2;
rcu_assign_pointer(event->data, data);
}
static void perf_mmap_data_free_rcu(struct rcu_head *rcu_head)
{
struct perf_mmap_data *data;
data = container_of(rcu_head, struct perf_mmap_data, rcu_head);
perf_mmap_data_free(data);
}
static void perf_mmap_data_release(struct perf_event *event)
{
struct perf_mmap_data *data = event->data;
WARN_ON(atomic_read(&event->mmap_count));
rcu_assign_pointer(event->data, NULL);
call_rcu(&data->rcu_head, perf_mmap_data_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);
}
static void perf_mmap_close(struct vm_area_struct *vma)
{
struct perf_event *event = vma->vm_file->private_data;
WARN_ON_ONCE(event->ctx->parent_ctx);
if (atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) {
unsigned long size = perf_data_size(event->data);
struct user_struct *user = current_user();
atomic_long_sub((size >> PAGE_SHIFT) + 1, &user->locked_vm);
vma->vm_mm->locked_vm -= event->data->nr_locked;
perf_mmap_data_release(event);
mutex_unlock(&event->mmap_mutex);
}
}
static const struct vm_operations_struct perf_mmap_vmops = {
.open = perf_mmap_open,
.close = perf_mmap_close,
.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();
unsigned long locked, lock_limit;
struct perf_mmap_data *data;
unsigned long vma_size;
unsigned long nr_pages;
long user_extra, extra;
int ret = 0;
if (!(vma->vm_flags & VM_SHARED))
return -EINVAL;
vma_size = vma->vm_end - vma->vm_start;
nr_pages = (vma_size / PAGE_SIZE) - 1;
/*
* If we have data 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;
if (vma->vm_pgoff != 0)
return -EINVAL;
WARN_ON_ONCE(event->ctx->parent_ctx);
mutex_lock(&event->mmap_mutex);
if (event->output) {
ret = -EINVAL;
goto unlock;
}
if (atomic_inc_not_zero(&event->mmap_count)) {
if (nr_pages != event->data->nr_pages)
ret = -EINVAL;
goto unlock;
}
user_extra = nr_pages + 1;
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) + user_extra;
extra = 0;
if (user_locked > user_lock_limit)
extra = user_locked - user_lock_limit;
lock_limit = rlimit(RLIMIT_MEMLOCK);
lock_limit >>= PAGE_SHIFT;
locked = vma->vm_mm->locked_vm + extra;
if ((locked > lock_limit) && perf_paranoid_tracepoint_raw() &&
!capable(CAP_IPC_LOCK)) {
ret = -EPERM;
goto unlock;
}
WARN_ON(event->data);
data = perf_mmap_data_alloc(event, nr_pages);
ret = -ENOMEM;
if (!data)
goto unlock;
ret = 0;
perf_mmap_data_init(event, data);
atomic_set(&event->mmap_count, 1);
atomic_long_add(user_extra, &user->locked_vm);
vma->vm_mm->locked_vm += extra;
event->data->nr_locked = extra;
if (vma->vm_flags & VM_WRITE)
event->data->writable = 1;
unlock:
mutex_unlock(&event->mmap_mutex);
vma->vm_flags |= VM_RESERVED;
vma->vm_ops = &perf_mmap_vmops;
return ret;
}
static int perf_fasync(int fd, struct file *filp, int on)
{
struct inode *inode = filp->f_path.dentry->d_inode;
struct perf_event *event = filp->private_data;
int retval;
mutex_lock(&inode->i_mutex);
retval = fasync_helper(fd, filp, on, &event->fasync);
mutex_unlock(&inode->i_mutex);
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_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.
*/
void perf_event_wakeup(struct perf_event *event)
{
wake_up_all(&event->waitq);
if (event->pending_kill) {
kill_fasync(&event->fasync, SIGIO, event->pending_kill);
event->pending_kill = 0;
}
}
/*
* Pending wakeups
*
* Handle the case where we need to wakeup up from NMI (or rq->lock) context.
*
* The NMI bit means we cannot possibly take locks. Therefore, maintain a
* single linked list and use cmpxchg() to add entries lockless.
*/
static void perf_pending_event(struct perf_pending_entry *entry)
{
struct perf_event *event = container_of(entry,
struct perf_event, pending);
if (event->pending_disable) {
event->pending_disable = 0;
__perf_event_disable(event);
}
if (event->pending_wakeup) {
event->pending_wakeup = 0;
perf_event_wakeup(event);
}
}
#define PENDING_TAIL ((struct perf_pending_entry *)-1UL)
static DEFINE_PER_CPU(struct perf_pending_entry *, perf_pending_head) = {
PENDING_TAIL,
};
static void perf_pending_queue(struct perf_pending_entry *entry,
void (*func)(struct perf_pending_entry *))
{
struct perf_pending_entry **head;
if (cmpxchg(&entry->next, NULL, PENDING_TAIL) != NULL)
return;
entry->func = func;
head = &get_cpu_var(perf_pending_head);
do {
entry->next = *head;
} while (cmpxchg(head, entry->next, entry) != entry->next);
set_perf_event_pending();
put_cpu_var(perf_pending_head);
}
static int __perf_pending_run(void)
{
struct perf_pending_entry *list;
int nr = 0;
list = xchg(&__get_cpu_var(perf_pending_head), PENDING_TAIL);
while (list != PENDING_TAIL) {
void (*func)(struct perf_pending_entry *);
struct perf_pending_entry *entry = list;
list = list->next;
func = entry->func;
entry->next = NULL;
/*
* Ensure we observe the unqueue before we issue the wakeup,
* so that we won't be waiting forever.
* -- see perf_not_pending().
*/
smp_wmb();
func(entry);
nr++;
}
return nr;
}
static inline int perf_not_pending(struct perf_event *event)
{
/*
* If we flush on whatever cpu we run, there is a chance we don't
* need to wait.
*/
get_cpu();
__perf_pending_run();
put_cpu();
/*
* Ensure we see the proper queue state before going to sleep
* so that we do not miss the wakeup. -- see perf_pending_handle()
*/
smp_rmb();
return event->pending.next == NULL;
}
static void perf_pending_sync(struct perf_event *event)
{
wait_event(event->waitq, perf_not_pending(event));
}
void perf_event_do_pending(void)
{
__perf_pending_run();
}
/*
* Callchain support -- arch specific
*/
__weak struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
{
return NULL;
}
__weak
void perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int skip)
{
}
/*
* We assume there is only KVM supporting the callbacks.
* Later on, we might change it to a list if there is
* another virtualization implementation supporting the callbacks.
*/
struct perf_guest_info_callbacks *perf_guest_cbs;
int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
{
perf_guest_cbs = cbs;
return 0;
}
EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
{
perf_guest_cbs = NULL;
return 0;
}
EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
/*
* Output
*/
static bool perf_output_space(struct perf_mmap_data *data, unsigned long tail,
unsigned long offset, unsigned long head)
{
unsigned long mask;
if (!data->writable)
return true;
mask = perf_data_size(data) - 1;
offset = (offset - tail) & mask;
head = (head - tail) & mask;
if ((int)(head - offset) < 0)
return false;
return true;
}
static void perf_output_wakeup(struct perf_output_handle *handle)
{
atomic_set(&handle->data->poll, POLL_IN);
if (handle->nmi) {
handle->event->pending_wakeup = 1;
perf_pending_queue(&handle->event->pending,
perf_pending_event);
} else
perf_event_wakeup(handle->event);
}
/*
* Curious locking construct.
*
* We need to ensure a later event_id doesn't publish a head when a former
* event_id isn't done writing. However since we need to deal with NMIs we
* cannot fully serialize things.
*
* What we do is serialize between CPUs so we only have to deal with NMI
* nesting on a single CPU.
*
* We only publish the head (and generate a wakeup) when the outer-most
* event_id completes.
*/
static void perf_output_lock(struct perf_output_handle *handle)
{
struct perf_mmap_data *data = handle->data;
int cur, cpu = get_cpu();
handle->locked = 0;
for (;;) {
cur = atomic_cmpxchg(&data->lock, -1, cpu);
if (cur == -1) {
handle->locked = 1;
break;
}
if (cur == cpu)
break;
cpu_relax();
}
}
static void perf_output_unlock(struct perf_output_handle *handle)
{
struct perf_mmap_data *data = handle->data;
unsigned long head;
int cpu;
data->done_head = data->head;
if (!handle->locked)
goto out;
again:
/*
* The xchg implies a full barrier that ensures all writes are done
* before we publish the new head, matched by a rmb() in userspace when
* reading this position.
*/
while ((head = atomic_long_xchg(&data->done_head, 0)))
data->user_page->data_head = head;
/*
* NMI can happen here, which means we can miss a done_head update.
*/
cpu = atomic_xchg(&data->lock, -1);
WARN_ON_ONCE(cpu != smp_processor_id());
/*
* Therefore we have to validate we did not indeed do so.
*/
if (unlikely(atomic_long_read(&data->done_head))) {
/*
* Since we had it locked, we can lock it again.
*/
while (atomic_cmpxchg(&data->lock, -1, cpu) != -1)
cpu_relax();
goto again;
}
if (atomic_xchg(&data->wakeup, 0))
perf_output_wakeup(handle);
out:
put_cpu();
}
void perf_output_copy(struct perf_output_handle *handle,
const void *buf, unsigned int len)
{
unsigned int pages_mask;
unsigned long offset;
unsigned int size;
void **pages;
offset = handle->offset;
pages_mask = handle->data->nr_pages - 1;
pages = handle->data->data_pages;
do {
unsigned long page_offset;
unsigned long page_size;
int nr;
nr = (offset >> PAGE_SHIFT) & pages_mask;
page_size = 1UL << (handle->data->data_order + PAGE_SHIFT);
page_offset = offset & (page_size - 1);
size = min_t(unsigned int, page_size - page_offset, len);
memcpy(pages[nr] + page_offset, buf, size);
len -= size;
buf += size;
offset += size;
} while (len);
handle->offset = offset;
/*
* Check we didn't copy past our reservation window, taking the
* possible unsigned int wrap into account.
*/
WARN_ON_ONCE(((long)(handle->head - handle->offset)) < 0);
}
int perf_output_begin(struct perf_output_handle *handle,
struct perf_event *event, unsigned int size,
int nmi, int sample)
{
struct perf_event *output_event;
struct perf_mmap_data *data;
unsigned long tail, offset, head;
int have_lost;
struct {
struct perf_event_header header;
u64 id;
u64 lost;
} lost_event;
rcu_read_lock();
/*
* For inherited events we send all the output towards the parent.
*/
if (event->parent)
event = event->parent;
output_event = rcu_dereference(event->output);
if (output_event)
event = output_event;
data = rcu_dereference(event->data);
if (!data)
goto out;
handle->data = data;
handle->event = event;
handle->nmi = nmi;
handle->sample = sample;
if (!data->nr_pages)
goto fail;
have_lost = atomic_read(&data->lost);
if (have_lost)
size += sizeof(lost_event);
perf_output_lock(handle);
do {
/*
* Userspace could choose to issue a mb() before updating the
* tail pointer. So that all reads will be completed before the
* write is issued.
*/
tail = ACCESS_ONCE(data->user_page->data_tail);
smp_rmb();
offset = head = atomic_long_read(&data->head);
head += size;
if (unlikely(!perf_output_space(data, tail, offset, head)))
goto fail;
} while (atomic_long_cmpxchg(&data->head, offset, head) != offset);
handle->offset = offset;
handle->head = head;
if (head - tail > data->watermark)
atomic_set(&data->wakeup, 1);
if (have_lost) {
lost_event.header.type = PERF_RECORD_LOST;
lost_event.header.misc = 0;
lost_event.header.size = sizeof(lost_event);
lost_event.id = event->id;
lost_event.lost = atomic_xchg(&data->lost, 0);
perf_output_put(handle, lost_event);
}
return 0;
fail:
atomic_inc(&data->lost);
perf_output_unlock(handle);
out:
rcu_read_unlock();
return -ENOSPC;
}
void perf_output_end(struct perf_output_handle *handle)
{
struct perf_event *event = handle->event;
struct perf_mmap_data *data = handle->data;
int wakeup_events = event->attr.wakeup_events;
if (handle->sample && wakeup_events) {
int events = atomic_inc_return(&data->events);
if (events >= wakeup_events) {
atomic_sub(wakeup_events, &data->events);
atomic_set(&data->wakeup, 1);
}
}
perf_output_unlock(handle);
rcu_read_unlock();
}
static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
{
/*
* only top level events have the pid namespace they were created in
*/
if (event->parent)
event = event->parent;
return task_tgid_nr_ns(p, event->ns);
}
static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
{
/*
* only top level events have the pid namespace they were created in
*/
if (event->parent)
event = event->parent;
return task_pid_nr_ns(p, event->ns);
}
static void perf_output_read_one(struct perf_output_handle *handle,
struct perf_event *event)
{
u64 read_format = event->attr.read_format;
u64 values[4];
int n = 0;
values[n++] = atomic64_read(&event->count);
if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
values[n++] = event->total_time_enabled +
atomic64_read(&event->child_total_time_enabled);
}
if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
values[n++] = event->total_time_running +
atomic64_read(&event->child_total_time_running);
}
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(event);
perf_output_copy(handle, values, n * sizeof(u64));
}
/*
* XXX PERF_FORMAT_GROUP vs inherited events seems difficult.
*/
static void perf_output_read_group(struct perf_output_handle *handle,
struct perf_event *event)
{
struct perf_event *leader = event->group_leader, *sub;
u64 read_format = event->attr.read_format;
u64 values[5];
int n = 0;
values[n++] = 1 + leader->nr_siblings;
if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
values[n++] = leader->total_time_enabled;
if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
values[n++] = leader->total_time_running;
if (leader != event)
leader->pmu->read(leader);
values[n++] = atomic64_read(&leader->count);
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(leader);
perf_output_copy(handle, values, n * sizeof(u64));
list_for_each_entry(sub, &leader->sibling_list, group_entry) {
n = 0;
if (sub != event)
sub->pmu->read(sub);
values[n++] = atomic64_read(&sub->count);
if (read_format & PERF_FORMAT_ID)
values[n++] = primary_event_id(sub);
perf_output_copy(handle, values, n * sizeof(u64));
}
}
static void perf_output_read(struct perf_output_handle *handle,
struct perf_event *event)
{
if (event->attr.read_format & PERF_FORMAT_GROUP)
perf_output_read_group(handle, event);
else
perf_output_read_one(handle, event);
}
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_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) {
if (data->callchain) {
int size = 1;
if (data->callchain)
size += data->callchain->nr;
size *= sizeof(u64);
perf_output_copy(handle, data->callchain, size);
} else {
u64 nr = 0;
perf_output_put(handle, nr);
}
}
if (sample_type & PERF_SAMPLE_RAW) {
if (data->raw) {
perf_output_put(handle, data->raw->size);
perf_output_copy(handle, data->raw->data,
data->raw->size);
} else {
struct {
u32 size;
u32 data;
} raw = {
.size = sizeof(u32),
.data = 0,
};
perf_output_put(handle, raw);
}
}
}
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;
data->type = sample_type;
header->type = PERF_RECORD_SAMPLE;
header->size = sizeof(*header);
header->misc = 0;
header->misc |= perf_misc_flags(regs);
if (sample_type & PERF_SAMPLE_IP) {
data->ip = perf_instruction_pointer(regs);
header->size += sizeof(data->ip);
}
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);
header->size += sizeof(data->tid_entry);
}
if (sample_type & PERF_SAMPLE_TIME) {
data->time = perf_clock();
header->size += sizeof(data->time);
}
if (sample_type & PERF_SAMPLE_ADDR)
header->size += sizeof(data->addr);
if (sample_type & PERF_SAMPLE_ID) {
data->id = primary_event_id(event);
header->size += sizeof(data->id);
}
if (sample_type & PERF_SAMPLE_STREAM_ID) {
data->stream_id = event->id;
header->size += sizeof(data->stream_id);
}
if (sample_type & PERF_SAMPLE_CPU) {
data->cpu_entry.cpu = raw_smp_processor_id();
data->cpu_entry.reserved = 0;
header->size += sizeof(data->cpu_entry);
}
if (sample_type & PERF_SAMPLE_PERIOD)
header->size += sizeof(data->period);
if (sample_type & PERF_SAMPLE_READ)
header->size += perf_event_read_size(event);
if (sample_type & PERF_SAMPLE_CALLCHAIN) {
int size = 1;
data->callchain = perf_callchain(regs);
if (data->callchain)
size += data->callchain->nr;
header->size += size * sizeof(u64);
}
if (sample_type & PERF_SAMPLE_RAW) {
int size = sizeof(u32);
if (data->raw)
size += data->raw->size;
else
size += sizeof(u32);
WARN_ON_ONCE(size & (sizeof(u64)-1));
header->size += size;
}
}
static void perf_event_output(struct perf_event *event, int nmi,
struct perf_sample_data *data,
struct pt_regs *regs)
{
struct perf_output_handle handle;
struct perf_event_header header;
perf_prepare_sample(&header, data, event, regs);
if (perf_output_begin(&handle, event, header.size, nmi, 1))
return;
perf_output_sample(&handle, &header, data, event);
perf_output_end(&handle);
}
/*
* 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_read_event read_event = {
.header = {
.type = PERF_RECORD_READ,
.misc = 0,
.size = sizeof(read_event) + perf_event_read_size(event),
},
.pid = perf_event_pid(event, task),
.tid = perf_event_tid(event, task),
};
int ret;
ret = perf_output_begin(&handle, event, read_event.header.size, 0, 0);
if (ret)
return;
perf_output_put(&handle, read_event);
perf_output_read(&handle, event);
perf_output_end(&handle);
}
/*
* task tracking -- fork/exit
*
* enabled by: attr.comm | attr.mmap | 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 void perf_event_task_output(struct perf_event *event,
struct perf_task_event *task_event)
{
struct perf_output_handle handle;
struct task_struct *task = task_event->task;
unsigned long flags;
int size, ret;
/*
* If this CPU attempts to acquire an rq lock held by a CPU spinning
* in perf_output_lock() from interrupt context, it's game over.
*/
local_irq_save(flags);
size = task_event->event_id.header.size;
ret = perf_output_begin(&handle, event, size, 0, 0);
if (ret) {
local_irq_restore(flags);
return;
}
task_event->event_id.pid = perf_event_pid(event, task);
task_event->event_id.ppid = perf_event_pid(event, current);
task_event->event_id.tid = perf_event_tid(event, task);
task_event->event_id.ptid = perf_event_tid(event, current);
perf_output_put(&handle, task_event->event_id);
perf_output_end(&handle);
local_irq_restore(flags);
}
static int perf_event_task_match(struct perf_event *event)
{
if (event->state < PERF_EVENT_STATE_INACTIVE)
return 0;
if (event->cpu != -1 && event->cpu != smp_processor_id())
return 0;
if (event->attr.comm || event->attr.mmap || event->attr.task)
return 1;
return 0;
}
static void perf_event_task_ctx(struct perf_event_context *ctx,
struct perf_task_event *task_event)
{
struct perf_event *event;
list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
if (perf_event_task_match(event))
perf_event_task_output(event, task_event);
}
}
static void perf_event_task_event(struct perf_task_event *task_event)
{
struct perf_cpu_context *cpuctx;
struct perf_event_context *ctx = task_event->task_ctx;
rcu_read_lock();
cpuctx = &get_cpu_var(perf_cpu_context);
perf_event_task_ctx(&cpuctx->ctx, task_event);
if (!ctx)
ctx = rcu_dereference(current->perf_event_ctxp);
if (ctx)
perf_event_task_ctx(ctx, task_event);
put_cpu_var(perf_cpu_context);
rcu_read_unlock();
}
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_clock(),
},
};
perf_event_task_event(&task_event);
}
void perf_event_fork(struct task_struct *task)
{
perf_event_task(task, NULL, 1);
}
/*
* 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 void perf_event_comm_output(struct perf_event *event,
struct perf_comm_event *comm_event)
{
struct perf_output_handle handle;
int size = comm_event->event_id.header.size;
int ret = perf_output_begin(&handle, event, size, 0, 0);
if (ret)
return;
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);
perf_output_copy(&handle, comm_event->comm,
comm_event->comm_size);
perf_output_end(&handle);
}
static int perf_event_comm_match(struct perf_event *event)
{
if (event->state < PERF_EVENT_STATE_INACTIVE)
return 0;
if (event->cpu != -1 && event->cpu != smp_processor_id())
return 0;
if (event->attr.comm)
return 1;
return 0;
}
static void perf_event_comm_ctx(struct perf_event_context *ctx,
struct perf_comm_event *comm_event)
{
struct perf_event *event;
list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
if (perf_event_comm_match(event))
perf_event_comm_output(event, comm_event);
}
}
static void perf_event_comm_event(struct perf_comm_event *comm_event)
{
struct perf_cpu_context *cpuctx;
struct perf_event_context *ctx;
unsigned int size;
char comm[TASK_COMM_LEN];
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;
rcu_read_lock();
cpuctx = &get_cpu_var(perf_cpu_context);
perf_event_comm_ctx(&cpuctx->ctx, comm_event);
ctx = rcu_dereference(current->perf_event_ctxp);
if (ctx)
perf_event_comm_ctx(ctx, comm_event);
put_cpu_var(perf_cpu_context);
rcu_read_unlock();
}
void perf_event_comm(struct task_struct *task)
{
struct perf_comm_event comm_event;
if (task->perf_event_ctxp)
perf_event_enable_on_exec(task);
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 = 0,
/* .size */
},
/* .pid */
/* .tid */
},
};
perf_event_comm_event(&comm_event);
}
/*
* mmap tracking
*/
struct perf_mmap_event {
struct vm_area_struct *vma;
const char *file_name;
int file_size;
struct {
struct perf_event_header header;
u32 pid;
u32 tid;
u64 start;
u64 len;
u64 pgoff;
} event_id;
};
static void perf_event_mmap_output(struct perf_event *event,
struct perf_mmap_event *mmap_event)
{
struct perf_output_handle handle;
int size = mmap_event->event_id.header.size;
int ret = perf_output_begin(&handle, event, size, 0, 0);
if (ret)
return;
mmap_event->event_id.pid = perf_event_pid(event, current);
mmap_event->event_id.tid = perf_event_tid(event, current);
perf_output_put(&handle, mmap_event->event_id);
perf_output_copy(&handle, mmap_event->file_name,
mmap_event->file_size);
perf_output_end(&handle);
}
static int perf_event_mmap_match(struct perf_event *event,
struct perf_mmap_event *mmap_event)
{
if (event->state < PERF_EVENT_STATE_INACTIVE)
return 0;
if (event->cpu != -1 && event->cpu != smp_processor_id())
return 0;
if (event->attr.mmap)
return 1;
return 0;
}
static void perf_event_mmap_ctx(struct perf_event_context *ctx,
struct perf_mmap_event *mmap_event)
{
struct perf_event *event;
list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
if (perf_event_mmap_match(event, mmap_event))
perf_event_mmap_output(event, mmap_event);
}
}
static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
{
struct perf_cpu_context *cpuctx;
struct perf_event_context *ctx;
struct vm_area_struct *vma = mmap_event->vma;
struct file *file = vma->vm_file;
unsigned int size;
char tmp[16];
char *buf = NULL;
const char *name;
memset(tmp, 0, sizeof(tmp));
if (file) {
/*
* d_path works from the end of the buffer backwards, so we
* need to add enough zero bytes after the string to handle
* the 64bit alignment we do later.
*/
buf = kzalloc(PATH_MAX + sizeof(u64), GFP_KERNEL);
if (!buf) {
name = strncpy(tmp, "//enomem", sizeof(tmp));
goto got_name;
}
name = d_path(&file->f_path, buf, PATH_MAX);
if (IS_ERR(name)) {
name = strncpy(tmp, "//toolong", sizeof(tmp));
goto got_name;
}
} else {
if (arch_vma_name(mmap_event->vma)) {
name = strncpy(tmp, arch_vma_name(mmap_event->vma),
sizeof(tmp));
goto got_name;
}
if (!vma->vm_mm) {
name = strncpy(tmp, "[vdso]", sizeof(tmp));
goto got_name;
}
name = strncpy(tmp, "//anon", sizeof(tmp));
goto got_name;
}
got_name:
size = ALIGN(strlen(name)+1, sizeof(u64));
mmap_event->file_name = name;
mmap_event->file_size = size;
mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size;
rcu_read_lock();
cpuctx = &get_cpu_var(perf_cpu_context);
perf_event_mmap_ctx(&cpuctx->ctx, mmap_event);
ctx = rcu_dereference(current->perf_event_ctxp);
if (ctx)
perf_event_mmap_ctx(ctx, mmap_event);
put_cpu_var(perf_cpu_context);
rcu_read_unlock();
kfree(buf);
}
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,
},
};
perf_event_mmap_event(&mmap_event);
}
/*
* IRQ throttle logging
*/
static void perf_log_throttle(struct perf_event *event, int enable)
{
struct perf_output_handle handle;
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_clock(),
.id = primary_event_id(event),
.stream_id = event->id,
};
if (enable)
throttle_event.header.type = PERF_RECORD_UNTHROTTLE;
ret = perf_output_begin(&handle, event, sizeof(throttle_event), 1, 0);
if (ret)
return;
perf_output_put(&handle, throttle_event);
perf_output_end(&handle);
}
/*
* Generic event overflow handling, sampling.
*/
static int __perf_event_overflow(struct perf_event *event, int nmi,
int throttle, struct perf_sample_data *data,
struct pt_regs *regs)
{
int events = atomic_read(&event->event_limit);
struct hw_perf_event *hwc = &event->hw;
int ret = 0;
throttle = (throttle && event->pmu->unthrottle != NULL);
if (!throttle) {
hwc->interrupts++;
} else {
if (hwc->interrupts != MAX_INTERRUPTS) {
hwc->interrupts++;
if (HZ * hwc->interrupts >
(u64)sysctl_perf_event_sample_rate) {
hwc->interrupts = MAX_INTERRUPTS;
perf_log_throttle(event, 0);
ret = 1;
}
} else {
/*
* Keep re-disabling events even though on the previous
* pass we disabled it - just in case we raced with a
* sched-in and the event got enabled again:
*/
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);
}
/*
* 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;
if (nmi) {
event->pending_disable = 1;
perf_pending_queue(&event->pending,
perf_pending_event);
} else
perf_event_disable(event);
}
if (event->overflow_handler)
event->overflow_handler(event, nmi, data, regs);
else
perf_event_output(event, nmi, data, regs);
return ret;
}
int perf_event_overflow(struct perf_event *event, int nmi,
struct perf_sample_data *data,
struct pt_regs *regs)
{
return __perf_event_overflow(event, nmi, 1, data, regs);
}
/*
* Generic software event infrastructure
*/
/*
* 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.
*/
static 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 = atomic64_read(&hwc->period_left);
if (val < 0)
return 0;
nr = div64_u64(period + val, period);
offset = nr * period;
val -= offset;
if (atomic64_cmpxchg(&hwc->period_left, old, val) != old)
goto again;
return nr;
}
static void perf_swevent_overflow(struct perf_event *event, u64 overflow,
int nmi, struct perf_sample_data *data,
struct pt_regs *regs)
{
struct hw_perf_event *hwc = &event->hw;
int throttle = 0;
data->period = event->hw.last_period;
if (!overflow)
overflow = perf_swevent_set_period(event);
if (hwc->interrupts == MAX_INTERRUPTS)
return;
for (; overflow; overflow--) {
if (__perf_event_overflow(event, nmi, throttle,
data, regs)) {
/*
* We inhibit the overflow from happening when
* hwc->interrupts == MAX_INTERRUPTS.
*/
break;
}
throttle = 1;
}
}
static void perf_swevent_unthrottle(struct perf_event *event)
{
/*
* Nothing to do, we already reset hwc->interrupts.
*/
}
static void perf_swevent_add(struct perf_event *event, u64 nr,
int nmi, struct perf_sample_data *data,
struct pt_regs *regs)
{
struct hw_perf_event *hwc = &event->hw;
atomic64_add(nr, &event->count);
if (!regs)
return;
if (!hwc->sample_period)
return;
if (nr == 1 && hwc->sample_period == 1 && !event->attr.freq)
return perf_swevent_overflow(event, 1, nmi, data, regs);
if (atomic64_add_negative(nr, &hwc->period_left))
return;
perf_swevent_overflow(event, 0, nmi, data, regs);
}
static int perf_tp_event_match(struct perf_event *event,
struct perf_sample_data *data);
static int perf_exclude_event(struct perf_event *event,
struct pt_regs *regs)
{
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;
if (event->attr.type == PERF_TYPE_TRACEPOINT &&
!perf_tp_event_match(event, data))
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 perf_cpu_context *ctx, u64 type, u32 event_id)
{
struct swevent_hlist *hlist;
hlist = rcu_dereference(ctx->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 perf_cpu_context *ctx, 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(ctx->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, int nmi,
struct perf_sample_data *data,
struct pt_regs *regs)
{
struct perf_cpu_context *cpuctx;
struct perf_event *event;
struct hlist_node *node;
struct hlist_head *head;
cpuctx = &__get_cpu_var(perf_cpu_context);
rcu_read_lock();
head = find_swevent_head_rcu(cpuctx, type, event_id);
if (!head)
goto end;
hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
if (perf_swevent_match(event, type, event_id, data, regs))
perf_swevent_add(event, nr, nmi, data, regs);
}
end:
rcu_read_unlock();
}
int perf_swevent_get_recursion_context(void)
{
struct perf_cpu_context *cpuctx = &get_cpu_var(perf_cpu_context);
int rctx;
if (in_nmi())
rctx = 3;
else if (in_irq())
rctx = 2;
else if (in_softirq())
rctx = 1;
else
rctx = 0;
if (cpuctx->recursion[rctx]) {
put_cpu_var(perf_cpu_context);
return -1;
}
cpuctx->recursion[rctx]++;
barrier();
return rctx;
}
EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context);
void perf_swevent_put_recursion_context(int rctx)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
barrier();
cpuctx->recursion[rctx]--;
put_cpu_var(perf_cpu_context);
}
EXPORT_SYMBOL_GPL(perf_swevent_put_recursion_context);
void __perf_sw_event(u32 event_id, u64 nr, int nmi,
struct pt_regs *regs, u64 addr)
{
struct perf_sample_data data;
int rctx;
rctx = perf_swevent_get_recursion_context();
if (rctx < 0)
return;
perf_sample_data_init(&data, addr);
do_perf_sw_event(PERF_TYPE_SOFTWARE, event_id, nr, nmi, &data, regs);
perf_swevent_put_recursion_context(rctx);
}
static void perf_swevent_read(struct perf_event *event)
{
}
static int perf_swevent_enable(struct perf_event *event)
{
struct hw_perf_event *hwc = &event->hw;
struct perf_cpu_context *cpuctx;
struct hlist_head *head;
cpuctx = &__get_cpu_var(perf_cpu_context);
if (hwc->sample_period) {
hwc->last_period = hwc->sample_period;
perf_swevent_set_period(event);
}
head = find_swevent_head(cpuctx, event);
if (WARN_ON_ONCE(!head))
return -EINVAL;
hlist_add_head_rcu(&event->hlist_entry, head);
return 0;
}
static void perf_swevent_disable(struct perf_event *event)
{
hlist_del_rcu(&event->hlist_entry);
}
static const struct pmu perf_ops_generic = {
.enable = perf_swevent_enable,
.disable = perf_swevent_disable,
.read = perf_swevent_read,
.unthrottle = perf_swevent_unthrottle,
};
/*
* 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);
event->pmu->read(event);
perf_sample_data_init(&data, 0);
data.period = event->hw.last_period;
regs = get_irq_regs();
if (regs && !perf_exclude_event(event, regs)) {
if (!(event->attr.exclude_idle && current->pid == 0))
if (perf_event_overflow(event, 0, &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;
hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hwc->hrtimer.function = perf_swevent_hrtimer;
if (hwc->sample_period) {
u64 period;
if (hwc->remaining) {
if (hwc->remaining < 0)
period = 10000;
else
period = hwc->remaining;
hwc->remaining = 0;
} else {
period = max_t(u64, 10000, hwc->sample_period);
}
__hrtimer_start_range_ns(&hwc->hrtimer,
ns_to_ktime(period), 0,
HRTIMER_MODE_REL, 0);
}
}
static void perf_swevent_cancel_hrtimer(struct perf_event *event)
{
struct hw_perf_event *hwc = &event->hw;
if (hwc->sample_period) {
ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer);
hwc->remaining = ktime_to_ns(remaining);
hrtimer_cancel(&hwc->hrtimer);
}
}
/*
* Software event: cpu wall time clock
*/
static void cpu_clock_perf_event_update(struct perf_event *event)
{
int cpu = raw_smp_processor_id();
s64 prev;
u64 now;
now = cpu_clock(cpu);
prev = atomic64_xchg(&event->hw.prev_count, now);
atomic64_add(now - prev, &event->count);
}
static int cpu_clock_perf_event_enable(struct perf_event *event)
{
struct hw_perf_event *hwc = &event->hw;
int cpu = raw_smp_processor_id();
atomic64_set(&hwc->prev_count, cpu_clock(cpu));
perf_swevent_start_hrtimer(event);
return 0;
}
static void cpu_clock_perf_event_disable(struct perf_event *event)
{
perf_swevent_cancel_hrtimer(event);
cpu_clock_perf_event_update(event);
}
static void cpu_clock_perf_event_read(struct perf_event *event)
{
cpu_clock_perf_event_update(event);
}
static const struct pmu perf_ops_cpu_clock = {
.enable = cpu_clock_perf_event_enable,
.disable = cpu_clock_perf_event_disable,
.read = cpu_clock_perf_event_read,
};
/*
* Software event: task time clock
*/
static void task_clock_perf_event_update(struct perf_event *event, u64 now)
{
u64 prev;
s64 delta;
prev = atomic64_xchg(&event->hw.prev_count, now);
delta = now - prev;
atomic64_add(delta, &event->count);
}
static int task_clock_perf_event_enable(struct perf_event *event)
{
struct hw_perf_event *hwc = &event->hw;
u64 now;
now = event->ctx->time;
atomic64_set(&hwc->prev_count, now);
perf_swevent_start_hrtimer(event);
return 0;
}
static void task_clock_perf_event_disable(struct perf_event *event)
{
perf_swevent_cancel_hrtimer(event);
task_clock_perf_event_update(event, event->ctx->time);
}
static void task_clock_perf_event_read(struct perf_event *event)
{
u64 time;
if (!in_nmi()) {
update_context_time(event->ctx);
time = event->ctx->time;
} else {
u64 now = perf_clock();
u64 delta = now - event->ctx->timestamp;
time = event->ctx->time + delta;
}
task_clock_perf_event_update(event, time);
}
static const struct pmu perf_ops_task_clock = {
.enable = task_clock_perf_event_enable,
.disable = task_clock_perf_event_disable,
.read = task_clock_perf_event_read,
};
/* Deref the hlist from the update side */
static inline struct swevent_hlist *
swevent_hlist_deref(struct perf_cpu_context *cpuctx)
{
return rcu_dereference_protected(cpuctx->swevent_hlist,
lockdep_is_held(&cpuctx->hlist_mutex));
}
static void swevent_hlist_release_rcu(struct rcu_head *rcu_head)
{
struct swevent_hlist *hlist;
hlist = container_of(rcu_head, struct swevent_hlist, rcu_head);
kfree(hlist);
}
static void swevent_hlist_release(struct perf_cpu_context *cpuctx)
{
struct swevent_hlist *hlist = swevent_hlist_deref(cpuctx);
if (!hlist)
return;
rcu_assign_pointer(cpuctx->swevent_hlist, NULL);
call_rcu(&hlist->rcu_head, swevent_hlist_release_rcu);
}
static void swevent_hlist_put_cpu(struct perf_event *event, int cpu)
{
struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
mutex_lock(&cpuctx->hlist_mutex);
if (!--cpuctx->hlist_refcount)
swevent_hlist_release(cpuctx);
mutex_unlock(&cpuctx->hlist_mutex);
}
static void swevent_hlist_put(struct perf_event *event)
{
int cpu;
if (event->cpu != -1) {
swevent_hlist_put_cpu(event, event->cpu);
return;
}
for_each_possible_cpu(cpu)
swevent_hlist_put_cpu(event, cpu);
}
static int swevent_hlist_get_cpu(struct perf_event *event, int cpu)
{
struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
int err = 0;
mutex_lock(&cpuctx->hlist_mutex);
if (!swevent_hlist_deref(cpuctx) && cpu_online(cpu)) {
struct swevent_hlist *hlist;
hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
if (!hlist) {
err = -ENOMEM;
goto exit;
}
rcu_assign_pointer(cpuctx->swevent_hlist, hlist);
}
cpuctx->hlist_refcount++;
exit:
mutex_unlock(&cpuctx->hlist_mutex);
return err;
}
static int swevent_hlist_get(struct perf_event *event)
{
int err;
int cpu, failed_cpu;
if (event->cpu != -1)
return swevent_hlist_get_cpu(event, event->cpu);
get_online_cpus();
for_each_possible_cpu(cpu) {
err = swevent_hlist_get_cpu(event, cpu);
if (err) {
failed_cpu = cpu;
goto fail;
}
}
put_online_cpus();
return 0;
fail:
for_each_possible_cpu(cpu) {
if (cpu == failed_cpu)
break;
swevent_hlist_put_cpu(event, cpu);
}
put_online_cpus();
return err;
}
#ifdef CONFIG_EVENT_TRACING
void perf_tp_event(int event_id, u64 addr, u64 count, void *record,
int entry_size, struct pt_regs *regs)
{
struct perf_sample_data data;
struct perf_raw_record raw = {
.size = entry_size,
.data = record,
};
perf_sample_data_init(&data, addr);
data.raw = &raw;
/* Trace events already protected against recursion */
do_perf_sw_event(PERF_TYPE_TRACEPOINT, event_id, count, 1,
&data, regs);
}
EXPORT_SYMBOL_GPL(perf_tp_event);
static int perf_tp_event_match(struct perf_event *event,
struct perf_sample_data *data)
{
void *record = data->raw->data;
if (likely(!event->filter) || filter_match_preds(event->filter, record))
return 1;
return 0;
}
static void tp_perf_event_destroy(struct perf_event *event)
{
perf_trace_disable(event->attr.config);
swevent_hlist_put(event);
}
static const struct pmu *tp_perf_event_init(struct perf_event *event)
{
int err;
/*
* Raw tracepoint data is a severe data leak, only allow root to
* have these.
*/
if ((event->attr.sample_type & PERF_SAMPLE_RAW) &&
perf_paranoid_tracepoint_raw() &&
!capable(CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
if (perf_trace_enable(event->attr.config))
return NULL;
event->destroy = tp_perf_event_destroy;
err = swevent_hlist_get(event);
if (err) {
perf_trace_disable(event->attr.config);
return ERR_PTR(err);
}
return &perf_ops_generic;
}
static int perf_event_set_filter(struct perf_event *event, void __user *arg)
{
char *filter_str;
int ret;
if (event->attr.type != PERF_TYPE_TRACEPOINT)
return -EINVAL;
filter_str = strndup_user(arg, PAGE_SIZE);
if (IS_ERR(filter_str))
return PTR_ERR(filter_str);
ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
kfree(filter_str);
return ret;
}
static void perf_event_free_filter(struct perf_event *event)
{
ftrace_profile_free_filter(event);
}
#else
static int perf_tp_event_match(struct perf_event *event,
struct perf_sample_data *data)
{
return 1;
}
static const struct pmu *tp_perf_event_init(struct perf_event *event)
{
return NULL;
}
static int perf_event_set_filter(struct perf_event *event, void __user *arg)
{
return -ENOENT;
}
static void perf_event_free_filter(struct perf_event *event)
{
}
#endif /* CONFIG_EVENT_TRACING */
#ifdef CONFIG_HAVE_HW_BREAKPOINT
static void bp_perf_event_destroy(struct perf_event *event)
{
release_bp_slot(event);
}
static const struct pmu *bp_perf_event_init(struct perf_event *bp)
{
int err;
err = register_perf_hw_breakpoint(bp);
if (err)
return ERR_PTR(err);
bp->destroy = bp_perf_event_destroy;
return &perf_ops_bp;
}
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);
if (!perf_exclude_event(bp, regs))
perf_swevent_add(bp, 1, 1, &sample, regs);
}
#else
static const struct pmu *bp_perf_event_init(struct perf_event *bp)
{
return NULL;
}
void perf_bp_event(struct perf_event *bp, void *regs)
{
}
#endif
atomic_t 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);
atomic_dec(&perf_swevent_enabled[event_id]);
swevent_hlist_put(event);
}
static const struct pmu *sw_perf_event_init(struct perf_event *event)
{
const struct pmu *pmu = NULL;
u64 event_id = event->attr.config;
/*
* Software events (currently) can't in general distinguish
* between user, kernel and hypervisor events.
* However, context switches and cpu migrations are considered
* to be kernel events, and page faults are never hypervisor
* events.
*/
switch (event_id) {
case PERF_COUNT_SW_CPU_CLOCK:
pmu = &perf_ops_cpu_clock;
break;
case PERF_COUNT_SW_TASK_CLOCK:
/*
* If the user instantiates this as a per-cpu event,
* use the cpu_clock event instead.
*/
if (event->ctx->task)
pmu = &perf_ops_task_clock;
else
pmu = &perf_ops_cpu_clock;
break;
case PERF_COUNT_SW_PAGE_FAULTS:
case PERF_COUNT_SW_PAGE_FAULTS_MIN:
case PERF_COUNT_SW_PAGE_FAULTS_MAJ:
case PERF_COUNT_SW_CONTEXT_SWITCHES:
case PERF_COUNT_SW_CPU_MIGRATIONS:
case PERF_COUNT_SW_ALIGNMENT_FAULTS:
case PERF_COUNT_SW_EMULATION_FAULTS:
if (!event->parent) {
int err;
err = swevent_hlist_get(event);
if (err)
return ERR_PTR(err);
atomic_inc(&perf_swevent_enabled[event_id]);
event->destroy = sw_perf_event_destroy;
}
pmu = &perf_ops_generic;
break;
}
return pmu;
}
/*
* Allocate and initialize a event structure
*/
static struct perf_event *
perf_event_alloc(struct perf_event_attr *attr,
int cpu,
struct perf_event_context *ctx,
struct perf_event *group_leader,
struct perf_event *parent_event,
perf_overflow_handler_t overflow_handler,
gfp_t gfpflags)
{
const struct pmu *pmu;
struct perf_event *event;
struct hw_perf_event *hwc;
long err;
event = kzalloc(sizeof(*event), gfpflags);
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->group_entry);
INIT_LIST_HEAD(&event->event_entry);
INIT_LIST_HEAD(&event->sibling_list);
init_waitqueue_head(&event->waitq);
mutex_init(&event->mmap_mutex);
event->cpu = cpu;
event->attr = *attr;
event->group_leader = group_leader;
event->pmu = NULL;
event->ctx = ctx;
event->oncpu = -1;
event->parent = parent_event;
event->ns = get_pid_ns(current->nsproxy->pid_ns);
event->id = atomic64_inc_return(&perf_event_id);
event->state = PERF_EVENT_STATE_INACTIVE;
if (!overflow_handler && parent_event)
overflow_handler = parent_event->overflow_handler;
event->overflow_handler = overflow_handler;
if (attr->disabled)
event->state = PERF_EVENT_STATE_OFF;
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;
atomic64_set(&hwc->period_left, hwc->sample_period);
/*
* we currently do not support PERF_FORMAT_GROUP on inherited events
*/
if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
goto done;
switch (attr->type) {
case PERF_TYPE_RAW:
case PERF_TYPE_HARDWARE:
case PERF_TYPE_HW_CACHE:
pmu = hw_perf_event_init(event);
break;
case PERF_TYPE_SOFTWARE:
pmu = sw_perf_event_init(event);
break;
case PERF_TYPE_TRACEPOINT:
pmu = tp_perf_event_init(event);
break;
case PERF_TYPE_BREAKPOINT:
pmu = bp_perf_event_init(event);
break;
default:
break;
}
done:
err = 0;
if (!pmu)
err = -EINVAL;
else if (IS_ERR(pmu))
err = PTR_ERR(pmu);
if (err) {
if (event->ns)
put_pid_ns(event->ns);
kfree(event);
return ERR_PTR(err);
}
event->pmu = pmu;
if (!event->parent) {
atomic_inc(&nr_events);
if (event->attr.mmap)
atomic_inc(&nr_mmap_events);
if (event->attr.comm)
atomic_inc(&nr_comm_events);
if (event->attr.task)
atomic_inc(&nr_task_events);
}
return event;
}
static int perf_copy_attr(struct perf_event_attr __user *uattr,
struct perf_event_attr *attr)
{
u32 size;
int ret;
if (!access_ok(VERIFY_WRITE, uattr, PERF_ATTR_SIZE_VER0))
return -EFAULT;
/*
* 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;
if (size > PAGE_SIZE) /* silly large */
goto err_size;
if (!size) /* abi compat */
size = PERF_ATTR_SIZE_VER0;
if (size < PERF_ATTR_SIZE_VER0)
goto err_size;
/*
* If we're handed a bigger struct than we know of,
* ensure all the unknown bits are 0 - i.e. new
* user-space does not rely on any kernel feature
* extensions we dont know about yet.
*/
if (size > sizeof(*attr)) {
unsigned char __user *addr;
unsigned char __user *end;
unsigned char val;
addr = (void __user *)uattr + sizeof(*attr);
end = (void __user *)uattr + size;
for (; addr < end; addr++) {
ret = get_user(val, addr);
if (ret)
return ret;
if (val)
goto err_size;
}
size = sizeof(*attr);
}
ret = copy_from_user(attr, uattr, size);
if (ret)
return -EFAULT;
/*
* If the type exists, the corresponding creation will verify
* the attr->config.
*/
if (attr->type >= PERF_TYPE_MAX)
return -EINVAL;
if (attr->__reserved_1)
return -EINVAL;
if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))
return -EINVAL;
if (attr->read_format & ~(PERF_FORMAT_MAX-1))
return -EINVAL;
out:
return ret;
err_size:
put_user(sizeof(*attr), &uattr->size);
ret = -E2BIG;
goto out;
}
static int perf_event_set_output(struct perf_event *event, int output_fd)
{
struct perf_event *output_event = NULL;
struct file *output_file = NULL;
struct perf_event *old_output;
int fput_needed = 0;
int ret = -EINVAL;
if (!output_fd)
goto set;
output_file = fget_light(output_fd, &fput_needed);
if (!output_file)
return -EBADF;
if (output_file->f_op != &perf_fops)
goto out;
output_event = output_file->private_data;
/* Don't chain output fds */
if (output_event->output)
goto out;
/* Don't set an output fd when we already have an output channel */
if (event->data)
goto out;
atomic_long_inc(&output_file->f_count);
set:
mutex_lock(&event->mmap_mutex);
old_output = event->output;
rcu_assign_pointer(event->output, output_event);
mutex_unlock(&event->mmap_mutex);
if (old_output) {
/*
* we need to make sure no existing perf_output_*()
* is still referencing this event.
*/
synchronize_rcu();
fput(old_output->filp);
}
ret = 0;
out:
fput_light(output_file, fput_needed);
return ret;
}
/**
* 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
*/
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 *event, *group_leader;
struct perf_event_attr attr;
struct perf_event_context *ctx;
struct file *event_file = NULL;
struct file *group_file = NULL;
int fput_needed = 0;
int fput_needed2 = 0;
int err;
/* for future expandability... */
if (flags & ~(PERF_FLAG_FD_NO_GROUP | PERF_FLAG_FD_OUTPUT))
return -EINVAL;
err = perf_copy_attr(attr_uptr, &attr);
if (err)
return err;
if (!attr.exclude_kernel) {
if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
return -EACCES;
}
if (attr.freq) {
if (attr.sample_freq > sysctl_perf_event_sample_rate)
return -EINVAL;
}
/*
* Get the target context (task or percpu):
*/
ctx = find_get_context(pid, cpu);
if (IS_ERR(ctx))
return PTR_ERR(ctx);
/*
* Look up the group leader (we will attach this event to it):
*/
group_leader = NULL;
if (group_fd != -1 && !(flags & PERF_FLAG_FD_NO_GROUP)) {
err = -EINVAL;
group_file = fget_light(group_fd, &fput_needed);
if (!group_file)
goto err_put_context;
if (group_file->f_op != &perf_fops)
goto err_put_context;
group_leader = group_file->private_data;
/*
* Do not allow a recursive hierarchy (this new sibling
* becoming part of another group-sibling):
*/
if (group_leader->group_leader != group_leader)
goto err_put_context;
/*
* Do not allow to attach to a group in a different
* task or CPU context:
*/
if (group_leader->ctx != ctx)
goto err_put_context;
/*
* Only a group leader can be exclusive or pinned
*/
if (attr.exclusive || attr.pinned)
goto err_put_context;
}
event = perf_event_alloc(&attr, cpu, ctx, group_leader,
NULL, NULL, GFP_KERNEL);
err = PTR_ERR(event);
if (IS_ERR(event))
goto err_put_context;
err = anon_inode_getfd("[perf_event]", &perf_fops, event, O_RDWR);
if (err < 0)
goto err_free_put_context;
event_file = fget_light(err, &fput_needed2);
if (!event_file)
goto err_free_put_context;
if (flags & PERF_FLAG_FD_OUTPUT) {
err = perf_event_set_output(event, group_fd);
if (err)
goto err_fput_free_put_context;
}
event->filp = event_file;
WARN_ON_ONCE(ctx->parent_ctx);
mutex_lock(&ctx->mutex);
perf_install_in_context(ctx, event, cpu);
++ctx->generation;
mutex_unlock(&ctx->mutex);
event->owner = current;
get_task_struct(current);
mutex_lock(&current->perf_event_mutex);
list_add_tail(&event->owner_entry, &current->perf_event_list);
mutex_unlock(&current->perf_event_mutex);
err_fput_free_put_context:
fput_light(event_file, fput_needed2);
err_free_put_context:
if (err < 0)
free_event(event);
err_put_context:
if (err < 0)
put_ctx(ctx);
fput_light(group_file, fput_needed);
return err;
}
/**
* perf_event_create_kernel_counter
*
* @attr: attributes of the counter to create
* @cpu: cpu in which the counter is bound
* @pid: task to profile
*/
struct perf_event *
perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
pid_t pid,
perf_overflow_handler_t overflow_handler)
{
struct perf_event *event;
struct perf_event_context *ctx;
int err;
/*
* Get the target context (task or percpu):
*/
ctx = find_get_context(pid, cpu);
if (IS_ERR(ctx)) {
err = PTR_ERR(ctx);
goto err_exit;
}
event = perf_event_alloc(attr, cpu, ctx, NULL,
NULL, overflow_handler, GFP_KERNEL);
if (IS_ERR(event)) {
err = PTR_ERR(event);
goto err_put_context;
}
event->filp = NULL;
WARN_ON_ONCE(ctx->parent_ctx);
mutex_lock(&ctx->mutex);
perf_install_in_context(ctx, event, cpu);
++ctx->generation;
mutex_unlock(&ctx->mutex);
event->owner = current;
get_task_struct(current);
mutex_lock(&current->perf_event_mutex);
list_add_tail(&event->owner_entry, &current->perf_event_list);
mutex_unlock(&current->perf_event_mutex);
return event;
err_put_context:
put_ctx(ctx);
err_exit:
return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
/*
* inherit a event from parent task to child task:
*/
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)
{
struct perf_event *child_event;
/*
* 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_ctx,
group_leader, parent_event,
NULL, GFP_KERNEL);
if (IS_ERR(child_event))
return child_event;
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_event->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;
atomic64_set(&hwc->period_left, sample_period);
}
child_event->overflow_handler = parent_event->overflow_handler;
/*
* Link it up in the child's context:
*/
add_event_to_ctx(child_event, child_ctx);
/*
* Get a reference to the parent filp - we will fput it
* when the child event exits. This is safe to do because
* we are in the parent and we know that the filp still
* exists and has a nonzero count:
*/
atomic_long_inc(&parent_event->filp->f_count);
/*
* Link this into the parent event's child list
*/
WARN_ON_ONCE(parent_event->ctx->parent_ctx);
mutex_lock(&parent_event->child_mutex);
list_add_tail(&child_event->child_list, &parent_event->child_list);
mutex_unlock(&parent_event->child_mutex);
return child_event;
}
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);
list_for_each_entry(sub, &parent_event->sibling_list, group_entry) {
child_ctr = inherit_event(sub, parent, parent_ctx,
child, leader, child_ctx);
if (IS_ERR(child_ctr))
return PTR_ERR(child_ctr);
}
return 0;
}
static void sync_child_event(struct perf_event *child_event,
struct task_struct *child)
{
struct perf_event *parent_event = child_event->parent;
u64 child_val;
if (child_event->attr.inherit_stat)
perf_event_read_event(child_event, child);
child_val = atomic64_read(&child_event->count);
/*
* Add back the child's count to the parent's count:
*/
atomic64_add(child_val, &parent_event->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);
/*
* Remove this event from the parent's list
*/
WARN_ON_ONCE(parent_event->ctx->parent_ctx);
mutex_lock(&parent_event->child_mutex);
list_del_init(&child_event->child_list);
mutex_unlock(&parent_event->child_mutex);
/*
* Release the parent event, if this was the last
* reference to it.
*/
fput(parent_event->filp);
}
static void
__perf_event_exit_task(struct perf_event *child_event,
struct perf_event_context *child_ctx,
struct task_struct *child)
{
struct perf_event *parent_event;
perf_event_remove_from_context(child_event);
parent_event = child_event->parent;
/*
* It can happen that parent exits first, and has events
* that are still around due to the child reference. These
* events need to be zapped - but otherwise linger.
*/
if (parent_event) {
sync_child_event(child_event, child);
free_event(child_event);
}
}
/*
* When a child task exits, feed back event values to parent events.
*/
void perf_event_exit_task(struct task_struct *child)
{
struct perf_event *child_event, *tmp;
struct perf_event_context *child_ctx;
unsigned long flags;
if (likely(!child->perf_event_ctxp)) {
perf_event_task(child, NULL, 0);
return;
}
local_irq_save(flags);
/*
* We can't reschedule here because interrupts are disabled,
* and either child is current or it is a task that can't be
* scheduled, so we are now safe from rescheduling changing
* our context.
*/
child_ctx = child->perf_event_ctxp;
__perf_event_task_sched_out(child_ctx);
/*
* Take the context lock here so that if find_get_context is
* reading child->perf_event_ctxp, we wait until it has
* incremented the context's refcount before we do put_ctx below.
*/
raw_spin_lock(&child_ctx->lock);
child->perf_event_ctxp = NULL;
/*
* If this context is a clone; unclone it so it can't get
* swapped to another process while we're removing all
* the events from it.
*/
unclone_ctx(child_ctx);
update_context_time(child_ctx);
raw_spin_unlock_irqrestore(&child_ctx->lock, flags);
/*
* 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);
/*
* We can recurse on the same lock type through:
*
* __perf_event_exit_task()
* sync_child_event()
* fput(parent_event->filp)
* perf_release()
* mutex_lock(&ctx->mutex)
*
* But since its the parent context it won't be the same instance.
*/
mutex_lock(&child_ctx->mutex);
again:
list_for_each_entry_safe(child_event, tmp, &child_ctx->pinned_groups,
group_entry)
__perf_event_exit_task(child_event, child_ctx, child);
list_for_each_entry_safe(child_event, tmp, &child_ctx->flexible_groups,
group_entry)
__perf_event_exit_task(child_event, child_ctx, child);
/*
* If the last event was a group event, it will have appended all
* its siblings to the list, but we obtained 'tmp' before that which
* will still point to the list head terminating the iteration.
*/
if (!list_empty(&child_ctx->pinned_groups) ||
!list_empty(&child_ctx->flexible_groups))
goto again;
mutex_unlock(&child_ctx->mutex);
put_ctx(child_ctx);
}
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);
fput(parent->filp);
list_del_event(event, ctx);
free_event(event);
}
/*
* free an unexposed, unused context as created by inheritance by
* init_task below, used by fork() in case of fail.
*/
void perf_event_free_task(struct task_struct *task)
{
struct perf_event_context *ctx = task->perf_event_ctxp;
struct perf_event *event, *tmp;
if (!ctx)
return;
mutex_lock(&ctx->mutex);
again:
list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry)
perf_free_event(event, ctx);
list_for_each_entry_safe(event, tmp, &ctx->flexible_groups,
group_entry)
perf_free_event(event, ctx);
if (!list_empty(&ctx->pinned_groups) ||
!list_empty(&ctx->flexible_groups))
goto again;
mutex_unlock(&ctx->mutex);
put_ctx(ctx);
}
static int
inherit_task_group(struct perf_event *event, struct task_struct *parent,
struct perf_event_context *parent_ctx,
struct task_struct *child,
int *inherited_all)
{
int ret;
struct perf_event_context *child_ctx = child->perf_event_ctxp;
if (!event->attr.inherit) {
*inherited_all = 0;
return 0;
}
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 = kzalloc(sizeof(struct perf_event_context),
GFP_KERNEL);
if (!child_ctx)
return -ENOMEM;
__perf_event_init_context(child_ctx, child);
child->perf_event_ctxp = child_ctx;
get_task_struct(child);
}
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
*/
int perf_event_init_task(struct task_struct *child)
{
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;
int ret = 0;
child->perf_event_ctxp = NULL;
mutex_init(&child->perf_event_mutex);
INIT_LIST_HEAD(&child->perf_event_list);
if (likely(!parent->perf_event_ctxp))
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);
/*
* 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:
*/
list_for_each_entry(event, &parent_ctx->pinned_groups, group_entry) {
ret = inherit_task_group(event, parent, parent_ctx, child,
&inherited_all);
if (ret)
break;
}
list_for_each_entry(event, &parent_ctx->flexible_groups, group_entry) {
ret = inherit_task_group(event, parent, parent_ctx, child,
&inherited_all);
if (ret)
break;
}
child_ctx = child->perf_event_ctxp;
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, it could get
* uncloned at any point, but that doesn't matter
* because the list of events and the generation
* count can't have changed since we took the mutex.
*/
cloned_ctx = rcu_dereference(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);
}
mutex_unlock(&parent_ctx->mutex);
perf_unpin_context(parent_ctx);
return ret;
}
static void __init perf_event_init_all_cpus(void)
{
int cpu;
struct perf_cpu_context *cpuctx;
for_each_possible_cpu(cpu) {
cpuctx = &per_cpu(perf_cpu_context, cpu);
mutex_init(&cpuctx->hlist_mutex);
__perf_event_init_context(&cpuctx->ctx, NULL);
}
}
static void __cpuinit perf_event_init_cpu(int cpu)
{
struct perf_cpu_context *cpuctx;
cpuctx = &per_cpu(perf_cpu_context, cpu);
spin_lock(&perf_resource_lock);
cpuctx->max_pertask = perf_max_events - perf_reserved_percpu;
spin_unlock(&perf_resource_lock);
mutex_lock(&cpuctx->hlist_mutex);
if (cpuctx->hlist_refcount > 0) {
struct swevent_hlist *hlist;
hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
WARN_ON_ONCE(!hlist);
rcu_assign_pointer(cpuctx->swevent_hlist, hlist);
}
mutex_unlock(&cpuctx->hlist_mutex);
}
#ifdef CONFIG_HOTPLUG_CPU
static void __perf_event_exit_cpu(void *info)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_event_context *ctx = &cpuctx->ctx;
struct perf_event *event, *tmp;
list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry)
__perf_event_remove_from_context(event);
list_for_each_entry_safe(event, tmp, &ctx->flexible_groups, group_entry)
__perf_event_remove_from_context(event);
}
static void perf_event_exit_cpu(int cpu)
{
struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
struct perf_event_context *ctx = &cpuctx->ctx;
mutex_lock(&cpuctx->hlist_mutex);
swevent_hlist_release(cpuctx);
mutex_unlock(&cpuctx->hlist_mutex);
mutex_lock(&ctx->mutex);
smp_call_function_single(cpu, __perf_event_exit_cpu, NULL, 1);
mutex_unlock(&ctx->mutex);
}
#else
static inline void perf_event_exit_cpu(int cpu) { }
#endif
static int __cpuinit
perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
{
unsigned int cpu = (long)hcpu;
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
perf_event_init_cpu(cpu);
break;
case CPU_DOWN_PREPARE:
case CPU_DOWN_PREPARE_FROZEN:
perf_event_exit_cpu(cpu);
break;
default:
break;
}
return NOTIFY_OK;
}
/*
* This has to have a higher priority than migration_notifier in sched.c.
*/
static struct notifier_block __cpuinitdata perf_cpu_nb = {
.notifier_call = perf_cpu_notify,
.priority = 20,
};
void __init perf_event_init(void)
{
perf_event_init_all_cpus();
perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_UP_PREPARE,
(void *)(long)smp_processor_id());
perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_ONLINE,
(void *)(long)smp_processor_id());
register_cpu_notifier(&perf_cpu_nb);
}
static ssize_t perf_show_reserve_percpu(struct sysdev_class *class,
struct sysdev_class_attribute *attr,
char *buf)
{
return sprintf(buf, "%d\n", perf_reserved_percpu);
}
static ssize_t
perf_set_reserve_percpu(struct sysdev_class *class,
struct sysdev_class_attribute *attr,
const char *buf,
size_t count)
{
struct perf_cpu_context *cpuctx;
unsigned long val;
int err, cpu, mpt;
err = strict_strtoul(buf, 10, &val);
if (err)
return err;
if (val > perf_max_events)
return -EINVAL;
spin_lock(&perf_resource_lock);
perf_reserved_percpu = val;
for_each_online_cpu(cpu) {
cpuctx = &per_cpu(perf_cpu_context, cpu);
raw_spin_lock_irq(&cpuctx->ctx.lock);
mpt = min(perf_max_events - cpuctx->ctx.nr_events,
perf_max_events - perf_reserved_percpu);
cpuctx->max_pertask = mpt;
raw_spin_unlock_irq(&cpuctx->ctx.lock);
}
spin_unlock(&perf_resource_lock);
return count;
}
static ssize_t perf_show_overcommit(struct sysdev_class *class,
struct sysdev_class_attribute *attr,
char *buf)
{
return sprintf(buf, "%d\n", perf_overcommit);
}
static ssize_t
perf_set_overcommit(struct sysdev_class *class,
struct sysdev_class_attribute *attr,
const char *buf, size_t count)
{
unsigned long val;
int err;
err = strict_strtoul(buf, 10, &val);
if (err)
return err;
if (val > 1)
return -EINVAL;
spin_lock(&perf_resource_lock);
perf_overcommit = val;
spin_unlock(&perf_resource_lock);
return count;
}
static SYSDEV_CLASS_ATTR(
reserve_percpu,
0644,
perf_show_reserve_percpu,
perf_set_reserve_percpu
);
static SYSDEV_CLASS_ATTR(
overcommit,
0644,
perf_show_overcommit,
perf_set_overcommit
);
static struct attribute *perfclass_attrs[] = {
&attr_reserve_percpu.attr,
&attr_overcommit.attr,
NULL
};
static struct attribute_group perfclass_attr_group = {
.attrs = perfclass_attrs,
.name = "perf_events",
};
static int __init perf_event_sysfs_init(void)
{
return sysfs_create_group(&cpu_sysdev_class.kset.kobj,
&perfclass_attr_group);
}
device_initcall(perf_event_sysfs_init);