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kernel-fxtec-pro1x/kernel/perf_counter.c
Peter Zijlstra bfbd3381e6 perf_counter: Implement more accurate per task statistics 
With the introduction of PERF_EVENT_READ we have the
possibility to provide accurate counter values for
individual tasks in a task hierarchy.

However, due to the lazy context switching used for similar
counter contexts our current per task counts are way off.

In order to maintain some of the lazy switch benefits we
don't disable it out-right, but simply iterate the active
counters and flip the values between the contexts.

This only reads the counters but does not need to reprogram
the full PMU.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-06-25 21:39:07 +02:00

4556 lines
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/*
* Performance counter 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/sysfs.h>
#include <linux/dcache.h>
#include <linux/percpu.h>
#include <linux/ptrace.h>
#include <linux/vmstat.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_counter.h>
#include <asm/irq_regs.h>
/*
* Each CPU has a list of per CPU counters:
*/
DEFINE_PER_CPU(struct perf_cpu_context, perf_cpu_context);
int perf_max_counters __read_mostly = 1;
static int perf_reserved_percpu __read_mostly;
static int perf_overcommit __read_mostly = 1;
static atomic_t nr_counters __read_mostly;
static atomic_t nr_mmap_counters __read_mostly;
static atomic_t nr_comm_counters __read_mostly;
/*
* perf counter paranoia level:
* 0 - not paranoid
* 1 - disallow cpu counters to unpriv
* 2 - disallow kernel profiling to unpriv
*/
int sysctl_perf_counter_paranoid __read_mostly;
static inline bool perf_paranoid_cpu(void)
{
return sysctl_perf_counter_paranoid > 0;
}
static inline bool perf_paranoid_kernel(void)
{
return sysctl_perf_counter_paranoid > 1;
}
int sysctl_perf_counter_mlock __read_mostly = 512; /* 'free' kb per user */
/*
* max perf counter sample rate
*/
int sysctl_perf_counter_sample_rate __read_mostly = 100000;
static atomic64_t perf_counter_id;
/*
* Lock for (sysadmin-configurable) counter reservations:
*/
static DEFINE_SPINLOCK(perf_resource_lock);
/*
* Architecture provided APIs - weak aliases:
*/
extern __weak const struct pmu *hw_perf_counter_init(struct perf_counter *counter)
{
return NULL;
}
void __weak hw_perf_disable(void) { barrier(); }
void __weak hw_perf_enable(void) { barrier(); }
void __weak hw_perf_counter_setup(int cpu) { barrier(); }
int __weak
hw_perf_group_sched_in(struct perf_counter *group_leader,
struct perf_cpu_context *cpuctx,
struct perf_counter_context *ctx, int cpu)
{
return 0;
}
void __weak perf_counter_print_debug(void) { }
static DEFINE_PER_CPU(int, disable_count);
void __perf_disable(void)
{
__get_cpu_var(disable_count)++;
}
bool __perf_enable(void)
{
return !--__get_cpu_var(disable_count);
}
void perf_disable(void)
{
__perf_disable();
hw_perf_disable();
}
void perf_enable(void)
{
if (__perf_enable())
hw_perf_enable();
}
static void get_ctx(struct perf_counter_context *ctx)
{
WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
}
static void free_ctx(struct rcu_head *head)
{
struct perf_counter_context *ctx;
ctx = container_of(head, struct perf_counter_context, rcu_head);
kfree(ctx);
}
static void put_ctx(struct perf_counter_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);
}
}
/*
* Get the perf_counter_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_counter_context *
perf_lock_task_context(struct task_struct *task, unsigned long *flags)
{
struct perf_counter_context *ctx;
rcu_read_lock();
retry:
ctx = rcu_dereference(task->perf_counter_ctxp);
if (ctx) {
/*
* If this context is a clone of another, it might
* get swapped for another underneath us by
* perf_counter_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.
*/
spin_lock_irqsave(&ctx->lock, *flags);
if (ctx != rcu_dereference(task->perf_counter_ctxp)) {
spin_unlock_irqrestore(&ctx->lock, *flags);
goto retry;
}
if (!atomic_inc_not_zero(&ctx->refcount)) {
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_counter_context *perf_pin_task_context(struct task_struct *task)
{
struct perf_counter_context *ctx;
unsigned long flags;
ctx = perf_lock_task_context(task, &flags);
if (ctx) {
++ctx->pin_count;
spin_unlock_irqrestore(&ctx->lock, flags);
}
return ctx;
}
static void perf_unpin_context(struct perf_counter_context *ctx)
{
unsigned long flags;
spin_lock_irqsave(&ctx->lock, flags);
--ctx->pin_count;
spin_unlock_irqrestore(&ctx->lock, flags);
put_ctx(ctx);
}
/*
* Add a counter from the lists for its context.
* Must be called with ctx->mutex and ctx->lock held.
*/
static void
list_add_counter(struct perf_counter *counter, struct perf_counter_context *ctx)
{
struct perf_counter *group_leader = counter->group_leader;
/*
* Depending on whether it is a standalone or sibling counter,
* add it straight to the context's counter list, or to the group
* leader's sibling list:
*/
if (group_leader == counter)
list_add_tail(&counter->list_entry, &ctx->counter_list);
else {
list_add_tail(&counter->list_entry, &group_leader->sibling_list);
group_leader->nr_siblings++;
}
list_add_rcu(&counter->event_entry, &ctx->event_list);
ctx->nr_counters++;
if (counter->attr.inherit_stat)
ctx->nr_stat++;
}
/*
* Remove a counter from the lists for its context.
* Must be called with ctx->mutex and ctx->lock held.
*/
static void
list_del_counter(struct perf_counter *counter, struct perf_counter_context *ctx)
{
struct perf_counter *sibling, *tmp;
if (list_empty(&counter->list_entry))
return;
ctx->nr_counters--;
if (counter->attr.inherit_stat)
ctx->nr_stat--;
list_del_init(&counter->list_entry);
list_del_rcu(&counter->event_entry);
if (counter->group_leader != counter)
counter->group_leader->nr_siblings--;
/*
* If this was a group counter with sibling counters then
* upgrade the siblings to singleton counters by adding them
* to the context list directly:
*/
list_for_each_entry_safe(sibling, tmp,
&counter->sibling_list, list_entry) {
list_move_tail(&sibling->list_entry, &ctx->counter_list);
sibling->group_leader = sibling;
}
}
static void
counter_sched_out(struct perf_counter *counter,
struct perf_cpu_context *cpuctx,
struct perf_counter_context *ctx)
{
if (counter->state != PERF_COUNTER_STATE_ACTIVE)
return;
counter->state = PERF_COUNTER_STATE_INACTIVE;
counter->tstamp_stopped = ctx->time;
counter->pmu->disable(counter);
counter->oncpu = -1;
if (!is_software_counter(counter))
cpuctx->active_oncpu--;
ctx->nr_active--;
if (counter->attr.exclusive || !cpuctx->active_oncpu)
cpuctx->exclusive = 0;
}
static void
group_sched_out(struct perf_counter *group_counter,
struct perf_cpu_context *cpuctx,
struct perf_counter_context *ctx)
{
struct perf_counter *counter;
if (group_counter->state != PERF_COUNTER_STATE_ACTIVE)
return;
counter_sched_out(group_counter, cpuctx, ctx);
/*
* Schedule out siblings (if any):
*/
list_for_each_entry(counter, &group_counter->sibling_list, list_entry)
counter_sched_out(counter, cpuctx, ctx);
if (group_counter->attr.exclusive)
cpuctx->exclusive = 0;
}
/*
* Cross CPU call to remove a performance counter
*
* We disable the counter on the hardware level first. After that we
* remove it from the context list.
*/
static void __perf_counter_remove_from_context(void *info)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_counter *counter = info;
struct perf_counter_context *ctx = counter->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;
spin_lock(&ctx->lock);
/*
* Protect the list operation against NMI by disabling the
* counters on a global level.
*/
perf_disable();
counter_sched_out(counter, cpuctx, ctx);
list_del_counter(counter, ctx);
if (!ctx->task) {
/*
* Allow more per task counters with respect to the
* reservation:
*/
cpuctx->max_pertask =
min(perf_max_counters - ctx->nr_counters,
perf_max_counters - perf_reserved_percpu);
}
perf_enable();
spin_unlock(&ctx->lock);
}
/*
* Remove the counter from a task's (or a CPU's) list of counters.
*
* Must be called with ctx->mutex held.
*
* CPU counters are removed with a smp call. For task counters we only
* call when the task is on a CPU.
*
* If counter->ctx is a cloned context, callers must make sure that
* every task struct that counter->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_counter_exit_task, it's OK because the
* context has been detached from its task.
*/
static void perf_counter_remove_from_context(struct perf_counter *counter)
{
struct perf_counter_context *ctx = counter->ctx;
struct task_struct *task = ctx->task;
if (!task) {
/*
* Per cpu counters are removed via an smp call and
* the removal is always sucessful.
*/
smp_call_function_single(counter->cpu,
__perf_counter_remove_from_context,
counter, 1);
return;
}
retry:
task_oncpu_function_call(task, __perf_counter_remove_from_context,
counter);
spin_lock_irq(&ctx->lock);
/*
* If the context is active we need to retry the smp call.
*/
if (ctx->nr_active && !list_empty(&counter->list_entry)) {
spin_unlock_irq(&ctx->lock);
goto retry;
}
/*
* The lock prevents that this context is scheduled in so we
* can remove the counter safely, if the call above did not
* succeed.
*/
if (!list_empty(&counter->list_entry)) {
list_del_counter(counter, ctx);
}
spin_unlock_irq(&ctx->lock);
}
static inline u64 perf_clock(void)
{
return cpu_clock(smp_processor_id());
}
/*
* Update the record of the current time in a context.
*/
static void update_context_time(struct perf_counter_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 counter.
*/
static void update_counter_times(struct perf_counter *counter)
{
struct perf_counter_context *ctx = counter->ctx;
u64 run_end;
if (counter->state < PERF_COUNTER_STATE_INACTIVE)
return;
counter->total_time_enabled = ctx->time - counter->tstamp_enabled;
if (counter->state == PERF_COUNTER_STATE_INACTIVE)
run_end = counter->tstamp_stopped;
else
run_end = ctx->time;
counter->total_time_running = run_end - counter->tstamp_running;
}
/*
* Update total_time_enabled and total_time_running for all counters in a group.
*/
static void update_group_times(struct perf_counter *leader)
{
struct perf_counter *counter;
update_counter_times(leader);
list_for_each_entry(counter, &leader->sibling_list, list_entry)
update_counter_times(counter);
}
/*
* Cross CPU call to disable a performance counter
*/
static void __perf_counter_disable(void *info)
{
struct perf_counter *counter = info;
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_counter_context *ctx = counter->ctx;
/*
* If this is a per-task counter, need to check whether this
* counter's task is the current task on this cpu.
*/
if (ctx->task && cpuctx->task_ctx != ctx)
return;
spin_lock(&ctx->lock);
/*
* If the counter is on, turn it off.
* If it is in error state, leave it in error state.
*/
if (counter->state >= PERF_COUNTER_STATE_INACTIVE) {
update_context_time(ctx);
update_counter_times(counter);
if (counter == counter->group_leader)
group_sched_out(counter, cpuctx, ctx);
else
counter_sched_out(counter, cpuctx, ctx);
counter->state = PERF_COUNTER_STATE_OFF;
}
spin_unlock(&ctx->lock);
}
/*
* Disable a counter.
*
* If counter->ctx is a cloned context, callers must make sure that
* every task struct that counter->ctx->task could possibly point to
* remains valid. This condition is satisifed when called through
* perf_counter_for_each_child or perf_counter_for_each because they
* hold the top-level counter's child_mutex, so any descendant that
* goes to exit will block in sync_child_counter.
* When called from perf_pending_counter it's OK because counter->ctx
* is the current context on this CPU and preemption is disabled,
* hence we can't get into perf_counter_task_sched_out for this context.
*/
static void perf_counter_disable(struct perf_counter *counter)
{
struct perf_counter_context *ctx = counter->ctx;
struct task_struct *task = ctx->task;
if (!task) {
/*
* Disable the counter on the cpu that it's on
*/
smp_call_function_single(counter->cpu, __perf_counter_disable,
counter, 1);
return;
}
retry:
task_oncpu_function_call(task, __perf_counter_disable, counter);
spin_lock_irq(&ctx->lock);
/*
* If the counter is still active, we need to retry the cross-call.
*/
if (counter->state == PERF_COUNTER_STATE_ACTIVE) {
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 (counter->state == PERF_COUNTER_STATE_INACTIVE) {
update_counter_times(counter);
counter->state = PERF_COUNTER_STATE_OFF;
}
spin_unlock_irq(&ctx->lock);
}
static int
counter_sched_in(struct perf_counter *counter,
struct perf_cpu_context *cpuctx,
struct perf_counter_context *ctx,
int cpu)
{
if (counter->state <= PERF_COUNTER_STATE_OFF)
return 0;
counter->state = PERF_COUNTER_STATE_ACTIVE;
counter->oncpu = cpu; /* TODO: put 'cpu' into cpuctx->cpu */
/*
* The new state must be visible before we turn it on in the hardware:
*/
smp_wmb();
if (counter->pmu->enable(counter)) {
counter->state = PERF_COUNTER_STATE_INACTIVE;
counter->oncpu = -1;
return -EAGAIN;
}
counter->tstamp_running += ctx->time - counter->tstamp_stopped;
if (!is_software_counter(counter))
cpuctx->active_oncpu++;
ctx->nr_active++;
if (counter->attr.exclusive)
cpuctx->exclusive = 1;
return 0;
}
static int
group_sched_in(struct perf_counter *group_counter,
struct perf_cpu_context *cpuctx,
struct perf_counter_context *ctx,
int cpu)
{
struct perf_counter *counter, *partial_group;
int ret;
if (group_counter->state == PERF_COUNTER_STATE_OFF)
return 0;
ret = hw_perf_group_sched_in(group_counter, cpuctx, ctx, cpu);
if (ret)
return ret < 0 ? ret : 0;
if (counter_sched_in(group_counter, cpuctx, ctx, cpu))
return -EAGAIN;
/*
* Schedule in siblings as one group (if any):
*/
list_for_each_entry(counter, &group_counter->sibling_list, list_entry) {
if (counter_sched_in(counter, cpuctx, ctx, cpu)) {
partial_group = counter;
goto group_error;
}
}
return 0;
group_error:
/*
* Groups can be scheduled in as one unit only, so undo any
* partial group before returning:
*/
list_for_each_entry(counter, &group_counter->sibling_list, list_entry) {
if (counter == partial_group)
break;
counter_sched_out(counter, cpuctx, ctx);
}
counter_sched_out(group_counter, cpuctx, ctx);
return -EAGAIN;
}
/*
* Return 1 for a group consisting entirely of software counters,
* 0 if the group contains any hardware counters.
*/
static int is_software_only_group(struct perf_counter *leader)
{
struct perf_counter *counter;
if (!is_software_counter(leader))
return 0;
list_for_each_entry(counter, &leader->sibling_list, list_entry)
if (!is_software_counter(counter))
return 0;
return 1;
}
/*
* Work out whether we can put this counter group on the CPU now.
*/
static int group_can_go_on(struct perf_counter *counter,
struct perf_cpu_context *cpuctx,
int can_add_hw)
{
/*
* Groups consisting entirely of software counters can always go on.
*/
if (is_software_only_group(counter))
return 1;
/*
* If an exclusive group is already on, no other hardware
* counters can go on.
*/
if (cpuctx->exclusive)
return 0;
/*
* If this group is exclusive and there are already
* counters on the CPU, it can't go on.
*/
if (counter->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_counter_to_ctx(struct perf_counter *counter,
struct perf_counter_context *ctx)
{
list_add_counter(counter, ctx);
counter->tstamp_enabled = ctx->time;
counter->tstamp_running = ctx->time;
counter->tstamp_stopped = ctx->time;
}
/*
* Cross CPU call to install and enable a performance counter
*
* 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_counter *counter = info;
struct perf_counter_context *ctx = counter->ctx;
struct perf_counter *leader = counter->group_leader;
int cpu = smp_processor_id();
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 counters.
*/
if (ctx->task && cpuctx->task_ctx != ctx) {
if (cpuctx->task_ctx || ctx->task != current)
return;
cpuctx->task_ctx = ctx;
}
spin_lock(&ctx->lock);
ctx->is_active = 1;
update_context_time(ctx);
/*
* Protect the list operation against NMI by disabling the
* counters on a global level. NOP for non NMI based counters.
*/
perf_disable();
add_counter_to_ctx(counter, ctx);
/*
* Don't put the counter on if it is disabled or if
* it is in a group and the group isn't on.
*/
if (counter->state != PERF_COUNTER_STATE_INACTIVE ||
(leader != counter && leader->state != PERF_COUNTER_STATE_ACTIVE))
goto unlock;
/*
* An exclusive counter can't go on if there are already active
* hardware counters, and no hardware counter can go on if there
* is already an exclusive counter on.
*/
if (!group_can_go_on(counter, cpuctx, 1))
err = -EEXIST;
else
err = counter_sched_in(counter, cpuctx, ctx, cpu);
if (err) {
/*
* This counter couldn't go on. If it is in a group
* then we have to pull the whole group off.
* If the counter group is pinned then put it in error state.
*/
if (leader != counter)
group_sched_out(leader, cpuctx, ctx);
if (leader->attr.pinned) {
update_group_times(leader);
leader->state = PERF_COUNTER_STATE_ERROR;
}
}
if (!err && !ctx->task && cpuctx->max_pertask)
cpuctx->max_pertask--;
unlock:
perf_enable();
spin_unlock(&ctx->lock);
}
/*
* Attach a performance counter to a context
*
* First we add the counter to the list with the hardware enable bit
* in counter->hw_config cleared.
*
* If the counter 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_counter_context *ctx,
struct perf_counter *counter,
int cpu)
{
struct task_struct *task = ctx->task;
if (!task) {
/*
* Per cpu counters are installed via an smp call and
* the install is always sucessful.
*/
smp_call_function_single(cpu, __perf_install_in_context,
counter, 1);
return;
}
retry:
task_oncpu_function_call(task, __perf_install_in_context,
counter);
spin_lock_irq(&ctx->lock);
/*
* we need to retry the smp call.
*/
if (ctx->is_active && list_empty(&counter->list_entry)) {
spin_unlock_irq(&ctx->lock);
goto retry;
}
/*
* The lock prevents that this context is scheduled in so we
* can add the counter safely, if it the call above did not
* succeed.
*/
if (list_empty(&counter->list_entry))
add_counter_to_ctx(counter, ctx);
spin_unlock_irq(&ctx->lock);
}
/*
* Cross CPU call to enable a performance counter
*/
static void __perf_counter_enable(void *info)
{
struct perf_counter *counter = info;
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_counter_context *ctx = counter->ctx;
struct perf_counter *leader = counter->group_leader;
int err;
/*
* If this is a per-task counter, need to check whether this
* counter'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;
}
spin_lock(&ctx->lock);
ctx->is_active = 1;
update_context_time(ctx);
if (counter->state >= PERF_COUNTER_STATE_INACTIVE)
goto unlock;
counter->state = PERF_COUNTER_STATE_INACTIVE;
counter->tstamp_enabled = ctx->time - counter->total_time_enabled;
/*
* If the counter is in a group and isn't the group leader,
* then don't put it on unless the group is on.
*/
if (leader != counter && leader->state != PERF_COUNTER_STATE_ACTIVE)
goto unlock;
if (!group_can_go_on(counter, cpuctx, 1)) {
err = -EEXIST;
} else {
perf_disable();
if (counter == leader)
err = group_sched_in(counter, cpuctx, ctx,
smp_processor_id());
else
err = counter_sched_in(counter, cpuctx, ctx,
smp_processor_id());
perf_enable();
}
if (err) {
/*
* If this counter can't go on and it's part of a
* group, then the whole group has to come off.
*/
if (leader != counter)
group_sched_out(leader, cpuctx, ctx);
if (leader->attr.pinned) {
update_group_times(leader);
leader->state = PERF_COUNTER_STATE_ERROR;
}
}
unlock:
spin_unlock(&ctx->lock);
}
/*
* Enable a counter.
*
* If counter->ctx is a cloned context, callers must make sure that
* every task struct that counter->ctx->task could possibly point to
* remains valid. This condition is satisfied when called through
* perf_counter_for_each_child or perf_counter_for_each as described
* for perf_counter_disable.
*/
static void perf_counter_enable(struct perf_counter *counter)
{
struct perf_counter_context *ctx = counter->ctx;
struct task_struct *task = ctx->task;
if (!task) {
/*
* Enable the counter on the cpu that it's on
*/
smp_call_function_single(counter->cpu, __perf_counter_enable,
counter, 1);
return;
}
spin_lock_irq(&ctx->lock);
if (counter->state >= PERF_COUNTER_STATE_INACTIVE)
goto out;
/*
* If the counter is in error state, clear that first.
* That way, if we see the counter 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 (counter->state == PERF_COUNTER_STATE_ERROR)
counter->state = PERF_COUNTER_STATE_OFF;
retry:
spin_unlock_irq(&ctx->lock);
task_oncpu_function_call(task, __perf_counter_enable, counter);
spin_lock_irq(&ctx->lock);
/*
* If the context is active and the counter is still off,
* we need to retry the cross-call.
*/
if (ctx->is_active && counter->state == PERF_COUNTER_STATE_OFF)
goto retry;
/*
* Since we have the lock this context can't be scheduled
* in, so we can change the state safely.
*/
if (counter->state == PERF_COUNTER_STATE_OFF) {
counter->state = PERF_COUNTER_STATE_INACTIVE;
counter->tstamp_enabled =
ctx->time - counter->total_time_enabled;
}
out:
spin_unlock_irq(&ctx->lock);
}
static int perf_counter_refresh(struct perf_counter *counter, int refresh)
{
/*
* not supported on inherited counters
*/
if (counter->attr.inherit)
return -EINVAL;
atomic_add(refresh, &counter->event_limit);
perf_counter_enable(counter);
return 0;
}
void __perf_counter_sched_out(struct perf_counter_context *ctx,
struct perf_cpu_context *cpuctx)
{
struct perf_counter *counter;
spin_lock(&ctx->lock);
ctx->is_active = 0;
if (likely(!ctx->nr_counters))
goto out;
update_context_time(ctx);
perf_disable();
if (ctx->nr_active) {
list_for_each_entry(counter, &ctx->counter_list, list_entry) {
if (counter != counter->group_leader)
counter_sched_out(counter, cpuctx, ctx);
else
group_sched_out(counter, cpuctx, ctx);
}
}
perf_enable();
out:
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 counters.
* If the number of enabled counters is the same, then the set
* of enabled counters should be the same, because these are both
* inherited contexts, therefore we can't access individual counters
* in them directly with an fd; we can only enable/disable all
* counters via prctl, or enable/disable all counters in a family
* via ioctl, which will have the same effect on both contexts.
*/
static int context_equiv(struct perf_counter_context *ctx1,
struct perf_counter_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_counter_read(void *counter);
static void __perf_counter_sync_stat(struct perf_counter *counter,
struct perf_counter *next_counter)
{
u64 value;
if (!counter->attr.inherit_stat)
return;
/*
* Update the counter value, we cannot use perf_counter_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 counter must be on the current CPU, therefore we
* don't need to use it.
*/
switch (counter->state) {
case PERF_COUNTER_STATE_ACTIVE:
__perf_counter_read(counter);
break;
case PERF_COUNTER_STATE_INACTIVE:
update_counter_times(counter);
break;
default:
break;
}
/*
* In order to keep per-task stats reliable we need to flip the counter
* values when we flip the contexts.
*/
value = atomic64_read(&next_counter->count);
value = atomic64_xchg(&counter->count, value);
atomic64_set(&next_counter->count, value);
/*
* XXX also sync time_enabled and time_running ?
*/
}
#define list_next_entry(pos, member) \
list_entry(pos->member.next, typeof(*pos), member)
static void perf_counter_sync_stat(struct perf_counter_context *ctx,
struct perf_counter_context *next_ctx)
{
struct perf_counter *counter, *next_counter;
if (!ctx->nr_stat)
return;
counter = list_first_entry(&ctx->event_list,
struct perf_counter, event_entry);
next_counter = list_first_entry(&next_ctx->event_list,
struct perf_counter, event_entry);
while (&counter->event_entry != &ctx->event_list &&
&next_counter->event_entry != &next_ctx->event_list) {
__perf_counter_sync_stat(counter, next_counter);
counter = list_next_entry(counter, event_entry);
next_counter = list_next_entry(counter, event_entry);
}
}
/*
* Called from scheduler to remove the counters of the current task,
* with interrupts disabled.
*
* We stop each counter and update the counter value in counter->count.
*
* This does not protect us against NMI, but disable()
* sets the disabled bit in the control field of counter _before_
* accessing the counter control register. If a NMI hits, then it will
* not restart the counter.
*/
void perf_counter_task_sched_out(struct task_struct *task,
struct task_struct *next, int cpu)
{
struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
struct perf_counter_context *ctx = task->perf_counter_ctxp;
struct perf_counter_context *next_ctx;
struct perf_counter_context *parent;
struct pt_regs *regs;
int do_switch = 1;
regs = task_pt_regs(task);
perf_swcounter_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, regs, 0);
if (likely(!ctx || !cpuctx->task_ctx))
return;
update_context_time(ctx);
rcu_read_lock();
parent = rcu_dereference(ctx->parent_ctx);
next_ctx = next->perf_counter_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.
*/
spin_lock(&ctx->lock);
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_counter_ctxp
*/
task->perf_counter_ctxp = next_ctx;
next->perf_counter_ctxp = ctx;
ctx->task = next;
next_ctx->task = task;
do_switch = 0;
perf_counter_sync_stat(ctx, next_ctx);
}
spin_unlock(&next_ctx->lock);
spin_unlock(&ctx->lock);
}
rcu_read_unlock();
if (do_switch) {
__perf_counter_sched_out(ctx, cpuctx);
cpuctx->task_ctx = NULL;
}
}
/*
* Called with IRQs disabled
*/
static void __perf_counter_task_sched_out(struct perf_counter_context *ctx)
{
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;
__perf_counter_sched_out(ctx, cpuctx);
cpuctx->task_ctx = NULL;
}
/*
* Called with IRQs disabled
*/
static void perf_counter_cpu_sched_out(struct perf_cpu_context *cpuctx)
{
__perf_counter_sched_out(&cpuctx->ctx, cpuctx);
}
static void
__perf_counter_sched_in(struct perf_counter_context *ctx,
struct perf_cpu_context *cpuctx, int cpu)
{
struct perf_counter *counter;
int can_add_hw = 1;
spin_lock(&ctx->lock);
ctx->is_active = 1;
if (likely(!ctx->nr_counters))
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.
*/
list_for_each_entry(counter, &ctx->counter_list, list_entry) {
if (counter->state <= PERF_COUNTER_STATE_OFF ||
!counter->attr.pinned)
continue;
if (counter->cpu != -1 && counter->cpu != cpu)
continue;
if (counter != counter->group_leader)
counter_sched_in(counter, cpuctx, ctx, cpu);
else {
if (group_can_go_on(counter, cpuctx, 1))
group_sched_in(counter, cpuctx, ctx, cpu);
}
/*
* If this pinned group hasn't been scheduled,
* put it in error state.
*/
if (counter->state == PERF_COUNTER_STATE_INACTIVE) {
update_group_times(counter);
counter->state = PERF_COUNTER_STATE_ERROR;
}
}
list_for_each_entry(counter, &ctx->counter_list, list_entry) {
/*
* Ignore counters in OFF or ERROR state, and
* ignore pinned counters since we did them already.
*/
if (counter->state <= PERF_COUNTER_STATE_OFF ||
counter->attr.pinned)
continue;
/*
* Listen to the 'cpu' scheduling filter constraint
* of counters:
*/
if (counter->cpu != -1 && counter->cpu != cpu)
continue;
if (counter != counter->group_leader) {
if (counter_sched_in(counter, cpuctx, ctx, cpu))
can_add_hw = 0;
} else {
if (group_can_go_on(counter, cpuctx, can_add_hw)) {
if (group_sched_in(counter, cpuctx, ctx, cpu))
can_add_hw = 0;
}
}
}
perf_enable();
out:
spin_unlock(&ctx->lock);
}
/*
* Called from scheduler to add the counters of the current task
* with interrupts disabled.
*
* We restore the counter value and then enable it.
*
* This does not protect us against NMI, but enable()
* sets the enabled bit in the control field of counter _before_
* accessing the counter control register. If a NMI hits, then it will
* keep the counter running.
*/
void perf_counter_task_sched_in(struct task_struct *task, int cpu)
{
struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
struct perf_counter_context *ctx = task->perf_counter_ctxp;
if (likely(!ctx))
return;
if (cpuctx->task_ctx == ctx)
return;
__perf_counter_sched_in(ctx, cpuctx, cpu);
cpuctx->task_ctx = ctx;
}
static void perf_counter_cpu_sched_in(struct perf_cpu_context *cpuctx, int cpu)
{
struct perf_counter_context *ctx = &cpuctx->ctx;
__perf_counter_sched_in(ctx, cpuctx, cpu);
}
#define MAX_INTERRUPTS (~0ULL)
static void perf_log_throttle(struct perf_counter *counter, int enable);
static void perf_log_period(struct perf_counter *counter, u64 period);
static void perf_adjust_period(struct perf_counter *counter, u64 events)
{
struct hw_perf_counter *hwc = &counter->hw;
u64 period, sample_period;
s64 delta;
events *= hwc->sample_period;
period = div64_u64(events, counter->attr.sample_freq);
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;
perf_log_period(counter, sample_period);
hwc->sample_period = sample_period;
}
static void perf_ctx_adjust_freq(struct perf_counter_context *ctx)
{
struct perf_counter *counter;
struct hw_perf_counter *hwc;
u64 interrupts, freq;
spin_lock(&ctx->lock);
list_for_each_entry(counter, &ctx->counter_list, list_entry) {
if (counter->state != PERF_COUNTER_STATE_ACTIVE)
continue;
hwc = &counter->hw;
interrupts = hwc->interrupts;
hwc->interrupts = 0;
/*
* unthrottle counters on the tick
*/
if (interrupts == MAX_INTERRUPTS) {
perf_log_throttle(counter, 1);
counter->pmu->unthrottle(counter);
interrupts = 2*sysctl_perf_counter_sample_rate/HZ;
}
if (!counter->attr.freq || !counter->attr.sample_freq)
continue;
/*
* if the specified freq < HZ then we need to skip ticks
*/
if (counter->attr.sample_freq < HZ) {
freq = counter->attr.sample_freq;
hwc->freq_count += freq;
hwc->freq_interrupts += interrupts;
if (hwc->freq_count < HZ)
continue;
interrupts = hwc->freq_interrupts;
hwc->freq_interrupts = 0;
hwc->freq_count -= HZ;
} else
freq = HZ;
perf_adjust_period(counter, freq * interrupts);
/*
* In order to avoid being stalled by an (accidental) huge
* sample period, force reset the sample period if we didn't
* get any events in this freq period.
*/
if (!interrupts) {
perf_disable();
counter->pmu->disable(counter);
atomic64_set(&hwc->period_left, 0);
counter->pmu->enable(counter);
perf_enable();
}
}
spin_unlock(&ctx->lock);
}
/*
* Round-robin a context's counters:
*/
static void rotate_ctx(struct perf_counter_context *ctx)
{
struct perf_counter *counter;
if (!ctx->nr_counters)
return;
spin_lock(&ctx->lock);
/*
* Rotate the first entry last (works just fine for group counters too):
*/
perf_disable();
list_for_each_entry(counter, &ctx->counter_list, list_entry) {
list_move_tail(&counter->list_entry, &ctx->counter_list);
break;
}
perf_enable();
spin_unlock(&ctx->lock);
}
void perf_counter_task_tick(struct task_struct *curr, int cpu)
{
struct perf_cpu_context *cpuctx;
struct perf_counter_context *ctx;
if (!atomic_read(&nr_counters))
return;
cpuctx = &per_cpu(perf_cpu_context, cpu);
ctx = curr->perf_counter_ctxp;
perf_ctx_adjust_freq(&cpuctx->ctx);
if (ctx)
perf_ctx_adjust_freq(ctx);
perf_counter_cpu_sched_out(cpuctx);
if (ctx)
__perf_counter_task_sched_out(ctx);
rotate_ctx(&cpuctx->ctx);
if (ctx)
rotate_ctx(ctx);
perf_counter_cpu_sched_in(cpuctx, cpu);
if (ctx)
perf_counter_task_sched_in(curr, cpu);
}
/*
* Cross CPU call to read the hardware counter
*/
static void __perf_counter_read(void *info)
{
struct perf_counter *counter = info;
struct perf_counter_context *ctx = counter->ctx;
unsigned long flags;
local_irq_save(flags);
if (ctx->is_active)
update_context_time(ctx);
counter->pmu->read(counter);
update_counter_times(counter);
local_irq_restore(flags);
}
static u64 perf_counter_read(struct perf_counter *counter)
{
/*
* If counter is enabled and currently active on a CPU, update the
* value in the counter structure:
*/
if (counter->state == PERF_COUNTER_STATE_ACTIVE) {
smp_call_function_single(counter->oncpu,
__perf_counter_read, counter, 1);
} else if (counter->state == PERF_COUNTER_STATE_INACTIVE) {
update_counter_times(counter);
}
return atomic64_read(&counter->count);
}
/*
* Initialize the perf_counter context in a task_struct:
*/
static void
__perf_counter_init_context(struct perf_counter_context *ctx,
struct task_struct *task)
{
memset(ctx, 0, sizeof(*ctx));
spin_lock_init(&ctx->lock);
mutex_init(&ctx->mutex);
INIT_LIST_HEAD(&ctx->counter_list);
INIT_LIST_HEAD(&ctx->event_list);
atomic_set(&ctx->refcount, 1);
ctx->task = task;
}
static struct perf_counter_context *find_get_context(pid_t pid, int cpu)
{
struct perf_counter_context *parent_ctx;
struct perf_counter_context *ctx;
struct perf_cpu_context *cpuctx;
struct task_struct *task;
unsigned long flags;
int err;
/*
* If cpu is not a wildcard then this is a percpu counter:
*/
if (cpu != -1) {
/* Must be root to operate on a CPU counter: */
if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
return ERR_PTR(-EACCES);
if (cpu < 0 || cpu > num_possible_cpus())
return ERR_PTR(-EINVAL);
/*
* We could be clever and allow to attach a counter to an
* offline CPU and activate it when the CPU comes up, but
* that's for later.
*/
if (!cpu_isset(cpu, cpu_online_map))
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 counters 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) {
parent_ctx = ctx->parent_ctx;
if (parent_ctx) {
put_ctx(parent_ctx);
ctx->parent_ctx = NULL; /* no longer a clone */
}
spin_unlock_irqrestore(&ctx->lock, flags);
}
if (!ctx) {
ctx = kmalloc(sizeof(struct perf_counter_context), GFP_KERNEL);
err = -ENOMEM;
if (!ctx)
goto errout;
__perf_counter_init_context(ctx, task);
get_ctx(ctx);
if (cmpxchg(&task->perf_counter_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 free_counter_rcu(struct rcu_head *head)
{
struct perf_counter *counter;
counter = container_of(head, struct perf_counter, rcu_head);
if (counter->ns)
put_pid_ns(counter->ns);
kfree(counter);
}
static void perf_pending_sync(struct perf_counter *counter);
static void free_counter(struct perf_counter *counter)
{
perf_pending_sync(counter);
if (!counter->parent) {
atomic_dec(&nr_counters);
if (counter->attr.mmap)
atomic_dec(&nr_mmap_counters);
if (counter->attr.comm)
atomic_dec(&nr_comm_counters);
}
if (counter->destroy)
counter->destroy(counter);
put_ctx(counter->ctx);
call_rcu(&counter->rcu_head, free_counter_rcu);
}
/*
* Called when the last reference to the file is gone.
*/
static int perf_release(struct inode *inode, struct file *file)
{
struct perf_counter *counter = file->private_data;
struct perf_counter_context *ctx = counter->ctx;
file->private_data = NULL;
WARN_ON_ONCE(ctx->parent_ctx);
mutex_lock(&ctx->mutex);
perf_counter_remove_from_context(counter);
mutex_unlock(&ctx->mutex);
mutex_lock(&counter->owner->perf_counter_mutex);
list_del_init(&counter->owner_entry);
mutex_unlock(&counter->owner->perf_counter_mutex);
put_task_struct(counter->owner);
free_counter(counter);
return 0;
}
/*
* Read the performance counter - simple non blocking version for now
*/
static ssize_t
perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count)
{
u64 values[4];
int n;
/*
* Return end-of-file for a read on a counter 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 (counter->state == PERF_COUNTER_STATE_ERROR)
return 0;
WARN_ON_ONCE(counter->ctx->parent_ctx);
mutex_lock(&counter->child_mutex);
values[0] = perf_counter_read(counter);
n = 1;
if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
values[n++] = counter->total_time_enabled +
atomic64_read(&counter->child_total_time_enabled);
if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
values[n++] = counter->total_time_running +
atomic64_read(&counter->child_total_time_running);
if (counter->attr.read_format & PERF_FORMAT_ID)
values[n++] = counter->id;
mutex_unlock(&counter->child_mutex);
if (count < n * sizeof(u64))
return -EINVAL;
count = n * sizeof(u64);
if (copy_to_user(buf, values, count))
return -EFAULT;
return count;
}
static ssize_t
perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
struct perf_counter *counter = file->private_data;
return perf_read_hw(counter, buf, count);
}
static unsigned int perf_poll(struct file *file, poll_table *wait)
{
struct perf_counter *counter = file->private_data;
struct perf_mmap_data *data;
unsigned int events = POLL_HUP;
rcu_read_lock();
data = rcu_dereference(counter->data);
if (data)
events = atomic_xchg(&data->poll, 0);
rcu_read_unlock();
poll_wait(file, &counter->waitq, wait);
return events;
}
static void perf_counter_reset(struct perf_counter *counter)
{
(void)perf_counter_read(counter);
atomic64_set(&counter->count, 0);
perf_counter_update_userpage(counter);
}
/*
* Holding the top-level counter's child_mutex means that any
* descendant process that has inherited this counter will block
* in sync_child_counter if it goes to exit, thus satisfying the
* task existence requirements of perf_counter_enable/disable.
*/
static void perf_counter_for_each_child(struct perf_counter *counter,
void (*func)(struct perf_counter *))
{
struct perf_counter *child;
WARN_ON_ONCE(counter->ctx->parent_ctx);
mutex_lock(&counter->child_mutex);
func(counter);
list_for_each_entry(child, &counter->child_list, child_list)
func(child);
mutex_unlock(&counter->child_mutex);
}
static void perf_counter_for_each(struct perf_counter *counter,
void (*func)(struct perf_counter *))
{
struct perf_counter_context *ctx = counter->ctx;
struct perf_counter *sibling;
WARN_ON_ONCE(ctx->parent_ctx);
mutex_lock(&ctx->mutex);
counter = counter->group_leader;
perf_counter_for_each_child(counter, func);
func(counter);
list_for_each_entry(sibling, &counter->sibling_list, list_entry)
perf_counter_for_each_child(counter, func);
mutex_unlock(&ctx->mutex);
}
static int perf_counter_period(struct perf_counter *counter, u64 __user *arg)
{
struct perf_counter_context *ctx = counter->ctx;
unsigned long size;
int ret = 0;
u64 value;
if (!counter->attr.sample_period)
return -EINVAL;
size = copy_from_user(&value, arg, sizeof(value));
if (size != sizeof(value))
return -EFAULT;
if (!value)
return -EINVAL;
spin_lock_irq(&ctx->lock);
if (counter->attr.freq) {
if (value > sysctl_perf_counter_sample_rate) {
ret = -EINVAL;
goto unlock;
}
counter->attr.sample_freq = value;
} else {
perf_log_period(counter, value);
counter->attr.sample_period = value;
counter->hw.sample_period = value;
}
unlock:
spin_unlock_irq(&ctx->lock);
return ret;
}
static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct perf_counter *counter = file->private_data;
void (*func)(struct perf_counter *);
u32 flags = arg;
switch (cmd) {
case PERF_COUNTER_IOC_ENABLE:
func = perf_counter_enable;
break;
case PERF_COUNTER_IOC_DISABLE:
func = perf_counter_disable;
break;
case PERF_COUNTER_IOC_RESET:
func = perf_counter_reset;
break;
case PERF_COUNTER_IOC_REFRESH:
return perf_counter_refresh(counter, arg);
case PERF_COUNTER_IOC_PERIOD:
return perf_counter_period(counter, (u64 __user *)arg);
default:
return -ENOTTY;
}
if (flags & PERF_IOC_FLAG_GROUP)
perf_counter_for_each(counter, func);
else
perf_counter_for_each_child(counter, func);
return 0;
}
int perf_counter_task_enable(void)
{
struct perf_counter *counter;
mutex_lock(&current->perf_counter_mutex);
list_for_each_entry(counter, &current->perf_counter_list, owner_entry)
perf_counter_for_each_child(counter, perf_counter_enable);
mutex_unlock(&current->perf_counter_mutex);
return 0;
}
int perf_counter_task_disable(void)
{
struct perf_counter *counter;
mutex_lock(&current->perf_counter_mutex);
list_for_each_entry(counter, &current->perf_counter_list, owner_entry)
perf_counter_for_each_child(counter, perf_counter_disable);
mutex_unlock(&current->perf_counter_mutex);
return 0;
}
static int perf_counter_index(struct perf_counter *counter)
{
if (counter->state != PERF_COUNTER_STATE_ACTIVE)
return 0;
return counter->hw.idx + 1 - PERF_COUNTER_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_counter_update_userpage(struct perf_counter *counter)
{
struct perf_counter_mmap_page *userpg;
struct perf_mmap_data *data;
rcu_read_lock();
data = rcu_dereference(counter->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_counter_index(counter);
userpg->offset = atomic64_read(&counter->count);
if (counter->state == PERF_COUNTER_STATE_ACTIVE)
userpg->offset -= atomic64_read(&counter->hw.prev_count);
userpg->time_enabled = counter->total_time_enabled +
atomic64_read(&counter->child_total_time_enabled);
userpg->time_running = counter->total_time_running +
atomic64_read(&counter->child_total_time_running);
barrier();
++userpg->lock;
preempt_enable();
unlock:
rcu_read_unlock();
}
static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct perf_counter *counter = 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(counter->data);
if (!data)
goto unlock;
if (vmf->pgoff == 0) {
vmf->page = virt_to_page(data->user_page);
} else {
int nr = vmf->pgoff - 1;
if ((unsigned)nr > data->nr_pages)
goto unlock;
if (vmf->flags & FAULT_FLAG_WRITE)
goto unlock;
vmf->page = virt_to_page(data->data_pages[nr]);
}
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 int perf_mmap_data_alloc(struct perf_counter *counter, int nr_pages)
{
struct perf_mmap_data *data;
unsigned long size;
int i;
WARN_ON(atomic_read(&counter->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->nr_pages = nr_pages;
atomic_set(&data->lock, -1);
rcu_assign_pointer(counter->data, data);
return 0;
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 -ENOMEM;
}
static void perf_mmap_free_page(unsigned long addr)
{
struct page *page = virt_to_page(addr);
page->mapping = NULL;
__free_page(page);
}
static void __perf_mmap_data_free(struct rcu_head *rcu_head)
{
struct perf_mmap_data *data;
int i;
data = container_of(rcu_head, struct perf_mmap_data, rcu_head);
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);
}
static void perf_mmap_data_free(struct perf_counter *counter)
{
struct perf_mmap_data *data = counter->data;
WARN_ON(atomic_read(&counter->mmap_count));
rcu_assign_pointer(counter->data, NULL);
call_rcu(&data->rcu_head, __perf_mmap_data_free);
}
static void perf_mmap_open(struct vm_area_struct *vma)
{
struct perf_counter *counter = vma->vm_file->private_data;
atomic_inc(&counter->mmap_count);
}
static void perf_mmap_close(struct vm_area_struct *vma)
{
struct perf_counter *counter = vma->vm_file->private_data;
WARN_ON_ONCE(counter->ctx->parent_ctx);
if (atomic_dec_and_mutex_lock(&counter->mmap_count, &counter->mmap_mutex)) {
struct user_struct *user = current_user();
atomic_long_sub(counter->data->nr_pages + 1, &user->locked_vm);
vma->vm_mm->locked_vm -= counter->data->nr_locked;
perf_mmap_data_free(counter);
mutex_unlock(&counter->mmap_mutex);
}
}
static 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_counter *counter = file->private_data;
unsigned long user_locked, user_lock_limit;
struct user_struct *user = current_user();
unsigned long locked, lock_limit;
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(counter->ctx->parent_ctx);
mutex_lock(&counter->mmap_mutex);
if (atomic_inc_not_zero(&counter->mmap_count)) {
if (nr_pages != counter->data->nr_pages)
ret = -EINVAL;
goto unlock;
}
user_extra = nr_pages + 1;
user_lock_limit = sysctl_perf_counter_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 = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
lock_limit >>= PAGE_SHIFT;
locked = vma->vm_mm->locked_vm + extra;
if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
ret = -EPERM;
goto unlock;
}
WARN_ON(counter->data);
ret = perf_mmap_data_alloc(counter, nr_pages);
if (ret)
goto unlock;
atomic_set(&counter->mmap_count, 1);
atomic_long_add(user_extra, &user->locked_vm);
vma->vm_mm->locked_vm += extra;
counter->data->nr_locked = extra;
if (vma->vm_flags & VM_WRITE)
counter->data->writable = 1;
unlock:
mutex_unlock(&counter->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_counter *counter = filp->private_data;
int retval;
mutex_lock(&inode->i_mutex);
retval = fasync_helper(fd, filp, on, &counter->fasync);
mutex_unlock(&inode->i_mutex);
if (retval < 0)
return retval;
return 0;
}
static const struct file_operations perf_fops = {
.release = perf_release,
.read = perf_read,
.poll = perf_poll,
.unlocked_ioctl = perf_ioctl,
.compat_ioctl = perf_ioctl,
.mmap = perf_mmap,
.fasync = perf_fasync,
};
/*
* Perf counter wakeup
*
* If there's data, ensure we set the poll() state and publish everything
* to user-space before waking everybody up.
*/
void perf_counter_wakeup(struct perf_counter *counter)
{
wake_up_all(&counter->waitq);
if (counter->pending_kill) {
kill_fasync(&counter->fasync, SIGIO, counter->pending_kill);
counter->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_counter(struct perf_pending_entry *entry)
{
struct perf_counter *counter = container_of(entry,
struct perf_counter, pending);
if (counter->pending_disable) {
counter->pending_disable = 0;
perf_counter_disable(counter);
}
if (counter->pending_wakeup) {
counter->pending_wakeup = 0;
perf_counter_wakeup(counter);
}
}
#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_counter_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_counter *counter)
{
/*
* 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 counter->pending.next == NULL;
}
static void perf_pending_sync(struct perf_counter *counter)
{
wait_event(counter->waitq, perf_not_pending(counter));
}
void perf_counter_do_pending(void)
{
__perf_pending_run();
}
/*
* Callchain support -- arch specific
*/
__weak struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
{
return NULL;
}
/*
* Output
*/
struct perf_output_handle {
struct perf_counter *counter;
struct perf_mmap_data *data;
unsigned long head;
unsigned long offset;
int nmi;
int sample;
int locked;
unsigned long flags;
};
static bool perf_output_space(struct perf_mmap_data *data,
unsigned int offset, unsigned int head)
{
unsigned long tail;
unsigned long mask;
if (!data->writable)
return true;
mask = (data->nr_pages << PAGE_SHIFT) - 1;
/*
* 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 = (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->counter->pending_wakeup = 1;
perf_pending_queue(&handle->counter->pending,
perf_pending_counter);
} else
perf_counter_wakeup(handle->counter);
}
/*
* Curious locking construct.
*
* We need to ensure a later event doesn't publish a head when a former
* event 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 completes.
*/
static void perf_output_lock(struct perf_output_handle *handle)
{
struct perf_mmap_data *data = handle->data;
int cpu;
handle->locked = 0;
local_irq_save(handle->flags);
cpu = smp_processor_id();
if (in_nmi() && atomic_read(&data->lock) == cpu)
return;
while (atomic_cmpxchg(&data->lock, -1, cpu) != -1)
cpu_relax();
handle->locked = 1;
}
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:
local_irq_restore(handle->flags);
}
static void perf_output_copy(struct perf_output_handle *handle,
const void *buf, unsigned int len)
{
unsigned int pages_mask;
unsigned int offset;
unsigned int size;
void **pages;
offset = handle->offset;
pages_mask = handle->data->nr_pages - 1;
pages = handle->data->data_pages;
do {
unsigned int page_offset;
int nr;
nr = (offset >> PAGE_SHIFT) & pages_mask;
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);
}
#define perf_output_put(handle, x) \
perf_output_copy((handle), &(x), sizeof(x))
static int perf_output_begin(struct perf_output_handle *handle,
struct perf_counter *counter, unsigned int size,
int nmi, int sample)
{
struct perf_mmap_data *data;
unsigned int offset, head;
int have_lost;
struct {
struct perf_event_header header;
u64 id;
u64 lost;
} lost_event;
/*
* For inherited counters we send all the output towards the parent.
*/
if (counter->parent)
counter = counter->parent;
rcu_read_lock();
data = rcu_dereference(counter->data);
if (!data)
goto out;
handle->data = data;
handle->counter = counter;
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 {
offset = head = atomic_long_read(&data->head);
head += size;
if (unlikely(!perf_output_space(data, offset, head)))
goto fail;
} while (atomic_long_cmpxchg(&data->head, offset, head) != offset);
handle->offset = offset;
handle->head = head;
if ((offset >> PAGE_SHIFT) != (head >> PAGE_SHIFT))
atomic_set(&data->wakeup, 1);
if (have_lost) {
lost_event.header.type = PERF_EVENT_LOST;
lost_event.header.misc = 0;
lost_event.header.size = sizeof(lost_event);
lost_event.id = counter->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;
}
static void perf_output_end(struct perf_output_handle *handle)
{
struct perf_counter *counter = handle->counter;
struct perf_mmap_data *data = handle->data;
int wakeup_events = counter->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_counter_pid(struct perf_counter *counter, struct task_struct *p)
{
/*
* only top level counters have the pid namespace they were created in
*/
if (counter->parent)
counter = counter->parent;
return task_tgid_nr_ns(p, counter->ns);
}
static u32 perf_counter_tid(struct perf_counter *counter, struct task_struct *p)
{
/*
* only top level counters have the pid namespace they were created in
*/
if (counter->parent)
counter = counter->parent;
return task_pid_nr_ns(p, counter->ns);
}
static void perf_counter_output(struct perf_counter *counter, int nmi,
struct perf_sample_data *data)
{
int ret;
u64 sample_type = counter->attr.sample_type;
struct perf_output_handle handle;
struct perf_event_header header;
u64 ip;
struct {
u32 pid, tid;
} tid_entry;
struct {
u64 id;
u64 counter;
} group_entry;
struct perf_callchain_entry *callchain = NULL;
int callchain_size = 0;
u64 time;
struct {
u32 cpu, reserved;
} cpu_entry;
header.type = 0;
header.size = sizeof(header);
header.misc = PERF_EVENT_MISC_OVERFLOW;
header.misc |= perf_misc_flags(data->regs);
if (sample_type & PERF_SAMPLE_IP) {
ip = perf_instruction_pointer(data->regs);
header.type |= PERF_SAMPLE_IP;
header.size += sizeof(ip);
}
if (sample_type & PERF_SAMPLE_TID) {
/* namespace issues */
tid_entry.pid = perf_counter_pid(counter, current);
tid_entry.tid = perf_counter_tid(counter, current);
header.type |= PERF_SAMPLE_TID;
header.size += sizeof(tid_entry);
}
if (sample_type & PERF_SAMPLE_TIME) {
/*
* Maybe do better on x86 and provide cpu_clock_nmi()
*/
time = sched_clock();
header.type |= PERF_SAMPLE_TIME;
header.size += sizeof(u64);
}
if (sample_type & PERF_SAMPLE_ADDR) {
header.type |= PERF_SAMPLE_ADDR;
header.size += sizeof(u64);
}
if (sample_type & PERF_SAMPLE_ID) {
header.type |= PERF_SAMPLE_ID;
header.size += sizeof(u64);
}
if (sample_type & PERF_SAMPLE_CPU) {
header.type |= PERF_SAMPLE_CPU;
header.size += sizeof(cpu_entry);
cpu_entry.cpu = raw_smp_processor_id();
}
if (sample_type & PERF_SAMPLE_PERIOD) {
header.type |= PERF_SAMPLE_PERIOD;
header.size += sizeof(u64);
}
if (sample_type & PERF_SAMPLE_GROUP) {
header.type |= PERF_SAMPLE_GROUP;
header.size += sizeof(u64) +
counter->nr_siblings * sizeof(group_entry);
}
if (sample_type & PERF_SAMPLE_CALLCHAIN) {
callchain = perf_callchain(data->regs);
if (callchain) {
callchain_size = (1 + callchain->nr) * sizeof(u64);
header.type |= PERF_SAMPLE_CALLCHAIN;
header.size += callchain_size;
}
}
ret = perf_output_begin(&handle, counter, header.size, nmi, 1);
if (ret)
return;
perf_output_put(&handle, header);
if (sample_type & PERF_SAMPLE_IP)
perf_output_put(&handle, ip);
if (sample_type & PERF_SAMPLE_TID)
perf_output_put(&handle, tid_entry);
if (sample_type & PERF_SAMPLE_TIME)
perf_output_put(&handle, time);
if (sample_type & PERF_SAMPLE_ADDR)
perf_output_put(&handle, data->addr);
if (sample_type & PERF_SAMPLE_ID)
perf_output_put(&handle, counter->id);
if (sample_type & PERF_SAMPLE_CPU)
perf_output_put(&handle, cpu_entry);
if (sample_type & PERF_SAMPLE_PERIOD)
perf_output_put(&handle, data->period);
/*
* XXX PERF_SAMPLE_GROUP vs inherited counters seems difficult.
*/
if (sample_type & PERF_SAMPLE_GROUP) {
struct perf_counter *leader, *sub;
u64 nr = counter->nr_siblings;
perf_output_put(&handle, nr);
leader = counter->group_leader;
list_for_each_entry(sub, &leader->sibling_list, list_entry) {
if (sub != counter)
sub->pmu->read(sub);
group_entry.id = sub->id;
group_entry.counter = atomic64_read(&sub->count);
perf_output_put(&handle, group_entry);
}
}
if (callchain)
perf_output_copy(&handle, callchain, callchain_size);
perf_output_end(&handle);
}
/*
* read event
*/
struct perf_read_event {
struct perf_event_header header;
u32 pid;
u32 tid;
u64 value;
u64 format[3];
};
static void
perf_counter_read_event(struct perf_counter *counter,
struct task_struct *task)
{
struct perf_output_handle handle;
struct perf_read_event event = {
.header = {
.type = PERF_EVENT_READ,
.misc = 0,
.size = sizeof(event) - sizeof(event.format),
},
.pid = perf_counter_pid(counter, task),
.tid = perf_counter_tid(counter, task),
.value = atomic64_read(&counter->count),
};
int ret, i = 0;
if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
event.header.size += sizeof(u64);
event.format[i++] = counter->total_time_enabled;
}
if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
event.header.size += sizeof(u64);
event.format[i++] = counter->total_time_running;
}
if (counter->attr.read_format & PERF_FORMAT_ID) {
u64 id;
event.header.size += sizeof(u64);
if (counter->parent)
id = counter->parent->id;
else
id = counter->id;
event.format[i++] = id;
}
ret = perf_output_begin(&handle, counter, event.header.size, 0, 0);
if (ret)
return;
perf_output_copy(&handle, &event, event.header.size);
perf_output_end(&handle);
}
/*
* fork tracking
*/
struct perf_fork_event {
struct task_struct *task;
struct {
struct perf_event_header header;
u32 pid;
u32 ppid;
} event;
};
static void perf_counter_fork_output(struct perf_counter *counter,
struct perf_fork_event *fork_event)
{
struct perf_output_handle handle;
int size = fork_event->event.header.size;
struct task_struct *task = fork_event->task;
int ret = perf_output_begin(&handle, counter, size, 0, 0);
if (ret)
return;
fork_event->event.pid = perf_counter_pid(counter, task);
fork_event->event.ppid = perf_counter_pid(counter, task->real_parent);
perf_output_put(&handle, fork_event->event);
perf_output_end(&handle);
}
static int perf_counter_fork_match(struct perf_counter *counter)
{
if (counter->attr.comm || counter->attr.mmap)
return 1;
return 0;
}
static void perf_counter_fork_ctx(struct perf_counter_context *ctx,
struct perf_fork_event *fork_event)
{
struct perf_counter *counter;
if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list))
return;
rcu_read_lock();
list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) {
if (perf_counter_fork_match(counter))
perf_counter_fork_output(counter, fork_event);
}
rcu_read_unlock();
}
static void perf_counter_fork_event(struct perf_fork_event *fork_event)
{
struct perf_cpu_context *cpuctx;
struct perf_counter_context *ctx;
cpuctx = &get_cpu_var(perf_cpu_context);
perf_counter_fork_ctx(&cpuctx->ctx, fork_event);
put_cpu_var(perf_cpu_context);
rcu_read_lock();
/*
* doesn't really matter which of the child contexts the
* events ends up in.
*/
ctx = rcu_dereference(current->perf_counter_ctxp);
if (ctx)
perf_counter_fork_ctx(ctx, fork_event);
rcu_read_unlock();
}
void perf_counter_fork(struct task_struct *task)
{
struct perf_fork_event fork_event;
if (!atomic_read(&nr_comm_counters) &&
!atomic_read(&nr_mmap_counters))
return;
fork_event = (struct perf_fork_event){
.task = task,
.event = {
.header = {
.type = PERF_EVENT_FORK,
.size = sizeof(fork_event.event),
},
},
};
perf_counter_fork_event(&fork_event);
}
/*
* 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;
};
static void perf_counter_comm_output(struct perf_counter *counter,
struct perf_comm_event *comm_event)
{
struct perf_output_handle handle;
int size = comm_event->event.header.size;
int ret = perf_output_begin(&handle, counter, size, 0, 0);
if (ret)
return;
comm_event->event.pid = perf_counter_pid(counter, comm_event->task);
comm_event->event.tid = perf_counter_tid(counter, comm_event->task);
perf_output_put(&handle, comm_event->event);
perf_output_copy(&handle, comm_event->comm,
comm_event->comm_size);
perf_output_end(&handle);
}
static int perf_counter_comm_match(struct perf_counter *counter)
{
if (counter->attr.comm)
return 1;
return 0;
}
static void perf_counter_comm_ctx(struct perf_counter_context *ctx,
struct perf_comm_event *comm_event)
{
struct perf_counter *counter;
if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list))
return;
rcu_read_lock();
list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) {
if (perf_counter_comm_match(counter))
perf_counter_comm_output(counter, comm_event);
}
rcu_read_unlock();
}
static void perf_counter_comm_event(struct perf_comm_event *comm_event)
{
struct perf_cpu_context *cpuctx;
struct perf_counter_context *ctx;
unsigned int size;
char *comm = comm_event->task->comm;
size = ALIGN(strlen(comm)+1, sizeof(u64));
comm_event->comm = comm;
comm_event->comm_size = size;
comm_event->event.header.size = sizeof(comm_event->event) + size;
cpuctx = &get_cpu_var(perf_cpu_context);
perf_counter_comm_ctx(&cpuctx->ctx, comm_event);
put_cpu_var(perf_cpu_context);
rcu_read_lock();
/*
* doesn't really matter which of the child contexts the
* events ends up in.
*/
ctx = rcu_dereference(current->perf_counter_ctxp);
if (ctx)
perf_counter_comm_ctx(ctx, comm_event);
rcu_read_unlock();
}
void perf_counter_comm(struct task_struct *task)
{
struct perf_comm_event comm_event;
if (!atomic_read(&nr_comm_counters))
return;
comm_event = (struct perf_comm_event){
.task = task,
.event = {
.header = { .type = PERF_EVENT_COMM, },
},
};
perf_counter_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;
};
static void perf_counter_mmap_output(struct perf_counter *counter,
struct perf_mmap_event *mmap_event)
{
struct perf_output_handle handle;
int size = mmap_event->event.header.size;
int ret = perf_output_begin(&handle, counter, size, 0, 0);
if (ret)
return;
mmap_event->event.pid = perf_counter_pid(counter, current);
mmap_event->event.tid = perf_counter_tid(counter, current);
perf_output_put(&handle, mmap_event->event);
perf_output_copy(&handle, mmap_event->file_name,
mmap_event->file_size);
perf_output_end(&handle);
}
static int perf_counter_mmap_match(struct perf_counter *counter,
struct perf_mmap_event *mmap_event)
{
if (counter->attr.mmap)
return 1;
return 0;
}
static void perf_counter_mmap_ctx(struct perf_counter_context *ctx,
struct perf_mmap_event *mmap_event)
{
struct perf_counter *counter;
if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list))
return;
rcu_read_lock();
list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) {
if (perf_counter_mmap_match(counter, mmap_event))
perf_counter_mmap_output(counter, mmap_event);
}
rcu_read_unlock();
}
static void perf_counter_mmap_event(struct perf_mmap_event *mmap_event)
{
struct perf_cpu_context *cpuctx;
struct perf_counter_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;
if (file) {
buf = kzalloc(PATH_MAX, 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 {
name = arch_vma_name(mmap_event->vma);
if (name)
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.header.size = sizeof(mmap_event->event) + size;
cpuctx = &get_cpu_var(perf_cpu_context);
perf_counter_mmap_ctx(&cpuctx->ctx, mmap_event);
put_cpu_var(perf_cpu_context);
rcu_read_lock();
/*
* doesn't really matter which of the child contexts the
* events ends up in.
*/
ctx = rcu_dereference(current->perf_counter_ctxp);
if (ctx)
perf_counter_mmap_ctx(ctx, mmap_event);
rcu_read_unlock();
kfree(buf);
}
void __perf_counter_mmap(struct vm_area_struct *vma)
{
struct perf_mmap_event mmap_event;
if (!atomic_read(&nr_mmap_counters))
return;
mmap_event = (struct perf_mmap_event){
.vma = vma,
.event = {
.header = { .type = PERF_EVENT_MMAP, },
.start = vma->vm_start,
.len = vma->vm_end - vma->vm_start,
.pgoff = vma->vm_pgoff,
},
};
perf_counter_mmap_event(&mmap_event);
}
/*
* Log sample_period changes so that analyzing tools can re-normalize the
* event flow.
*/
struct freq_event {
struct perf_event_header header;
u64 time;
u64 id;
u64 period;
};
static void perf_log_period(struct perf_counter *counter, u64 period)
{
struct perf_output_handle handle;
struct freq_event event;
int ret;
if (counter->hw.sample_period == period)
return;
if (counter->attr.sample_type & PERF_SAMPLE_PERIOD)
return;
event = (struct freq_event) {
.header = {
.type = PERF_EVENT_PERIOD,
.misc = 0,
.size = sizeof(event),
},
.time = sched_clock(),
.id = counter->id,
.period = period,
};
ret = perf_output_begin(&handle, counter, sizeof(event), 1, 0);
if (ret)
return;
perf_output_put(&handle, event);
perf_output_end(&handle);
}
/*
* IRQ throttle logging
*/
static void perf_log_throttle(struct perf_counter *counter, int enable)
{
struct perf_output_handle handle;
int ret;
struct {
struct perf_event_header header;
u64 time;
u64 id;
} throttle_event = {
.header = {
.type = PERF_EVENT_THROTTLE + 1,
.misc = 0,
.size = sizeof(throttle_event),
},
.time = sched_clock(),
.id = counter->id,
};
ret = perf_output_begin(&handle, counter, sizeof(throttle_event), 1, 0);
if (ret)
return;
perf_output_put(&handle, throttle_event);
perf_output_end(&handle);
}
/*
* Generic counter overflow handling, sampling.
*/
int perf_counter_overflow(struct perf_counter *counter, int nmi,
struct perf_sample_data *data)
{
int events = atomic_read(&counter->event_limit);
int throttle = counter->pmu->unthrottle != NULL;
struct hw_perf_counter *hwc = &counter->hw;
int ret = 0;
if (!throttle) {
hwc->interrupts++;
} else {
if (hwc->interrupts != MAX_INTERRUPTS) {
hwc->interrupts++;
if (HZ * hwc->interrupts >
(u64)sysctl_perf_counter_sample_rate) {
hwc->interrupts = MAX_INTERRUPTS;
perf_log_throttle(counter, 0);
ret = 1;
}
} else {
/*
* Keep re-disabling counters even though on the previous
* pass we disabled it - just in case we raced with a
* sched-in and the counter got enabled again:
*/
ret = 1;
}
}
if (counter->attr.freq) {
u64 now = sched_clock();
s64 delta = now - hwc->freq_stamp;
hwc->freq_stamp = now;
if (delta > 0 && delta < TICK_NSEC)
perf_adjust_period(counter, NSEC_PER_SEC / (int)delta);
}
/*
* XXX event_limit might not quite work as expected on inherited
* counters
*/
counter->pending_kill = POLL_IN;
if (events && atomic_dec_and_test(&counter->event_limit)) {
ret = 1;
counter->pending_kill = POLL_HUP;
if (nmi) {
counter->pending_disable = 1;
perf_pending_queue(&counter->pending,
perf_pending_counter);
} else
perf_counter_disable(counter);
}
perf_counter_output(counter, nmi, data);
return ret;
}
/*
* Generic software counter infrastructure
*/
static void perf_swcounter_update(struct perf_counter *counter)
{
struct hw_perf_counter *hwc = &counter->hw;
u64 prev, now;
s64 delta;
again:
prev = atomic64_read(&hwc->prev_count);
now = atomic64_read(&hwc->count);
if (atomic64_cmpxchg(&hwc->prev_count, prev, now) != prev)
goto again;
delta = now - prev;
atomic64_add(delta, &counter->count);
atomic64_sub(delta, &hwc->period_left);
}
static void perf_swcounter_set_period(struct perf_counter *counter)
{
struct hw_perf_counter *hwc = &counter->hw;
s64 left = atomic64_read(&hwc->period_left);
s64 period = hwc->sample_period;
if (unlikely(left <= -period)) {
left = period;
atomic64_set(&hwc->period_left, left);
hwc->last_period = period;
}
if (unlikely(left <= 0)) {
left += period;
atomic64_add(period, &hwc->period_left);
hwc->last_period = period;
}
atomic64_set(&hwc->prev_count, -left);
atomic64_set(&hwc->count, -left);
}
static enum hrtimer_restart perf_swcounter_hrtimer(struct hrtimer *hrtimer)
{
enum hrtimer_restart ret = HRTIMER_RESTART;
struct perf_sample_data data;
struct perf_counter *counter;
u64 period;
counter = container_of(hrtimer, struct perf_counter, hw.hrtimer);
counter->pmu->read(counter);
data.addr = 0;
data.regs = get_irq_regs();
/*
* In case we exclude kernel IPs or are somehow not in interrupt
* context, provide the next best thing, the user IP.
*/
if ((counter->attr.exclude_kernel || !data.regs) &&
!counter->attr.exclude_user)
data.regs = task_pt_regs(current);
if (data.regs) {
if (perf_counter_overflow(counter, 0, &data))
ret = HRTIMER_NORESTART;
}
period = max_t(u64, 10000, counter->hw.sample_period);
hrtimer_forward_now(hrtimer, ns_to_ktime(period));
return ret;
}
static void perf_swcounter_overflow(struct perf_counter *counter,
int nmi, struct perf_sample_data *data)
{
data->period = counter->hw.last_period;
perf_swcounter_update(counter);
perf_swcounter_set_period(counter);
if (perf_counter_overflow(counter, nmi, data))
/* soft-disable the counter */
;
}
static int perf_swcounter_is_counting(struct perf_counter *counter)
{
struct perf_counter_context *ctx;
unsigned long flags;
int count;
if (counter->state == PERF_COUNTER_STATE_ACTIVE)
return 1;
if (counter->state != PERF_COUNTER_STATE_INACTIVE)
return 0;
/*
* If the counter is inactive, it could be just because
* its task is scheduled out, or because it's in a group
* which could not go on the PMU. We want to count in
* the first case but not the second. If the context is
* currently active then an inactive software counter must
* be the second case. If it's not currently active then
* we need to know whether the counter was active when the
* context was last active, which we can determine by
* comparing counter->tstamp_stopped with ctx->time.
*
* We are within an RCU read-side critical section,
* which protects the existence of *ctx.
*/
ctx = counter->ctx;
spin_lock_irqsave(&ctx->lock, flags);
count = 1;
/* Re-check state now we have the lock */
if (counter->state < PERF_COUNTER_STATE_INACTIVE ||
counter->ctx->is_active ||
counter->tstamp_stopped < ctx->time)
count = 0;
spin_unlock_irqrestore(&ctx->lock, flags);
return count;
}
static int perf_swcounter_match(struct perf_counter *counter,
enum perf_type_id type,
u32 event, struct pt_regs *regs)
{
if (!perf_swcounter_is_counting(counter))
return 0;
if (counter->attr.type != type)
return 0;
if (counter->attr.config != event)
return 0;
if (regs) {
if (counter->attr.exclude_user && user_mode(regs))
return 0;
if (counter->attr.exclude_kernel && !user_mode(regs))
return 0;
}
return 1;
}
static void perf_swcounter_add(struct perf_counter *counter, u64 nr,
int nmi, struct perf_sample_data *data)
{
int neg = atomic64_add_negative(nr, &counter->hw.count);
if (counter->hw.sample_period && !neg && data->regs)
perf_swcounter_overflow(counter, nmi, data);
}
static void perf_swcounter_ctx_event(struct perf_counter_context *ctx,
enum perf_type_id type,
u32 event, u64 nr, int nmi,
struct perf_sample_data *data)
{
struct perf_counter *counter;
if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list))
return;
rcu_read_lock();
list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) {
if (perf_swcounter_match(counter, type, event, data->regs))
perf_swcounter_add(counter, nr, nmi, data);
}
rcu_read_unlock();
}
static int *perf_swcounter_recursion_context(struct perf_cpu_context *cpuctx)
{
if (in_nmi())
return &cpuctx->recursion[3];
if (in_irq())
return &cpuctx->recursion[2];
if (in_softirq())
return &cpuctx->recursion[1];
return &cpuctx->recursion[0];
}
static void do_perf_swcounter_event(enum perf_type_id type, u32 event,
u64 nr, int nmi,
struct perf_sample_data *data)
{
struct perf_cpu_context *cpuctx = &get_cpu_var(perf_cpu_context);
int *recursion = perf_swcounter_recursion_context(cpuctx);
struct perf_counter_context *ctx;
if (*recursion)
goto out;
(*recursion)++;
barrier();
perf_swcounter_ctx_event(&cpuctx->ctx, type, event,
nr, nmi, data);
rcu_read_lock();
/*
* doesn't really matter which of the child contexts the
* events ends up in.
*/
ctx = rcu_dereference(current->perf_counter_ctxp);
if (ctx)
perf_swcounter_ctx_event(ctx, type, event, nr, nmi, data);
rcu_read_unlock();
barrier();
(*recursion)--;
out:
put_cpu_var(perf_cpu_context);
}
void __perf_swcounter_event(u32 event, u64 nr, int nmi,
struct pt_regs *regs, u64 addr)
{
struct perf_sample_data data = {
.regs = regs,
.addr = addr,
};
do_perf_swcounter_event(PERF_TYPE_SOFTWARE, event, nr, nmi, &data);
}
static void perf_swcounter_read(struct perf_counter *counter)
{
perf_swcounter_update(counter);
}
static int perf_swcounter_enable(struct perf_counter *counter)
{
perf_swcounter_set_period(counter);
return 0;
}
static void perf_swcounter_disable(struct perf_counter *counter)
{
perf_swcounter_update(counter);
}
static const struct pmu perf_ops_generic = {
.enable = perf_swcounter_enable,
.disable = perf_swcounter_disable,
.read = perf_swcounter_read,
};
/*
* Software counter: cpu wall time clock
*/
static void cpu_clock_perf_counter_update(struct perf_counter *counter)
{
int cpu = raw_smp_processor_id();
s64 prev;
u64 now;
now = cpu_clock(cpu);
prev = atomic64_read(&counter->hw.prev_count);
atomic64_set(&counter->hw.prev_count, now);
atomic64_add(now - prev, &counter->count);
}
static int cpu_clock_perf_counter_enable(struct perf_counter *counter)
{
struct hw_perf_counter *hwc = &counter->hw;
int cpu = raw_smp_processor_id();
atomic64_set(&hwc->prev_count, cpu_clock(cpu));
hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hwc->hrtimer.function = perf_swcounter_hrtimer;
if (hwc->sample_period) {
u64 period = max_t(u64, 10000, hwc->sample_period);
__hrtimer_start_range_ns(&hwc->hrtimer,
ns_to_ktime(period), 0,
HRTIMER_MODE_REL, 0);
}
return 0;
}
static void cpu_clock_perf_counter_disable(struct perf_counter *counter)
{
if (counter->hw.sample_period)
hrtimer_cancel(&counter->hw.hrtimer);
cpu_clock_perf_counter_update(counter);
}
static void cpu_clock_perf_counter_read(struct perf_counter *counter)
{
cpu_clock_perf_counter_update(counter);
}
static const struct pmu perf_ops_cpu_clock = {
.enable = cpu_clock_perf_counter_enable,
.disable = cpu_clock_perf_counter_disable,
.read = cpu_clock_perf_counter_read,
};
/*
* Software counter: task time clock
*/
static void task_clock_perf_counter_update(struct perf_counter *counter, u64 now)
{
u64 prev;
s64 delta;
prev = atomic64_xchg(&counter->hw.prev_count, now);
delta = now - prev;
atomic64_add(delta, &counter->count);
}
static int task_clock_perf_counter_enable(struct perf_counter *counter)
{
struct hw_perf_counter *hwc = &counter->hw;
u64 now;
now = counter->ctx->time;
atomic64_set(&hwc->prev_count, now);
hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hwc->hrtimer.function = perf_swcounter_hrtimer;
if (hwc->sample_period) {
u64 period = max_t(u64, 10000, hwc->sample_period);
__hrtimer_start_range_ns(&hwc->hrtimer,
ns_to_ktime(period), 0,
HRTIMER_MODE_REL, 0);
}
return 0;
}
static void task_clock_perf_counter_disable(struct perf_counter *counter)
{
if (counter->hw.sample_period)
hrtimer_cancel(&counter->hw.hrtimer);
task_clock_perf_counter_update(counter, counter->ctx->time);
}
static void task_clock_perf_counter_read(struct perf_counter *counter)
{
u64 time;
if (!in_nmi()) {
update_context_time(counter->ctx);
time = counter->ctx->time;
} else {
u64 now = perf_clock();
u64 delta = now - counter->ctx->timestamp;
time = counter->ctx->time + delta;
}
task_clock_perf_counter_update(counter, time);
}
static const struct pmu perf_ops_task_clock = {
.enable = task_clock_perf_counter_enable,
.disable = task_clock_perf_counter_disable,
.read = task_clock_perf_counter_read,
};
#ifdef CONFIG_EVENT_PROFILE
void perf_tpcounter_event(int event_id)
{
struct perf_sample_data data = {
.regs = get_irq_regs();
.addr = 0,
};
if (!data.regs)
data.regs = task_pt_regs(current);
do_perf_swcounter_event(PERF_TYPE_TRACEPOINT, event_id, 1, 1, &data);
}
EXPORT_SYMBOL_GPL(perf_tpcounter_event);
extern int ftrace_profile_enable(int);
extern void ftrace_profile_disable(int);
static void tp_perf_counter_destroy(struct perf_counter *counter)
{
ftrace_profile_disable(perf_event_id(&counter->attr));
}
static const struct pmu *tp_perf_counter_init(struct perf_counter *counter)
{
int event_id = perf_event_id(&counter->attr);
int ret;
ret = ftrace_profile_enable(event_id);
if (ret)
return NULL;
counter->destroy = tp_perf_counter_destroy;
return &perf_ops_generic;
}
#else
static const struct pmu *tp_perf_counter_init(struct perf_counter *counter)
{
return NULL;
}
#endif
atomic_t perf_swcounter_enabled[PERF_COUNT_SW_MAX];
static void sw_perf_counter_destroy(struct perf_counter *counter)
{
u64 event = counter->attr.config;
WARN_ON(counter->parent);
atomic_dec(&perf_swcounter_enabled[event]);
}
static const struct pmu *sw_perf_counter_init(struct perf_counter *counter)
{
const struct pmu *pmu = NULL;
u64 event = counter->attr.config;
/*
* Software counters (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) {
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 counter,
* use the cpu_clock counter instead.
*/
if (counter->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:
if (!counter->parent) {
atomic_inc(&perf_swcounter_enabled[event]);
counter->destroy = sw_perf_counter_destroy;
}
pmu = &perf_ops_generic;
break;
}
return pmu;
}
/*
* Allocate and initialize a counter structure
*/
static struct perf_counter *
perf_counter_alloc(struct perf_counter_attr *attr,
int cpu,
struct perf_counter_context *ctx,
struct perf_counter *group_leader,
struct perf_counter *parent_counter,
gfp_t gfpflags)
{
const struct pmu *pmu;
struct perf_counter *counter;
struct hw_perf_counter *hwc;
long err;
counter = kzalloc(sizeof(*counter), gfpflags);
if (!counter)
return ERR_PTR(-ENOMEM);
/*
* Single counters are their own group leaders, with an
* empty sibling list:
*/
if (!group_leader)
group_leader = counter;
mutex_init(&counter->child_mutex);
INIT_LIST_HEAD(&counter->child_list);
INIT_LIST_HEAD(&counter->list_entry);
INIT_LIST_HEAD(&counter->event_entry);
INIT_LIST_HEAD(&counter->sibling_list);
init_waitqueue_head(&counter->waitq);
mutex_init(&counter->mmap_mutex);
counter->cpu = cpu;
counter->attr = *attr;
counter->group_leader = group_leader;
counter->pmu = NULL;
counter->ctx = ctx;
counter->oncpu = -1;
counter->parent = parent_counter;
counter->ns = get_pid_ns(current->nsproxy->pid_ns);
counter->id = atomic64_inc_return(&perf_counter_id);
counter->state = PERF_COUNTER_STATE_INACTIVE;
if (attr->disabled)
counter->state = PERF_COUNTER_STATE_OFF;
pmu = NULL;
hwc = &counter->hw;
hwc->sample_period = attr->sample_period;
if (attr->freq && attr->sample_freq)
hwc->sample_period = 1;
atomic64_set(&hwc->period_left, hwc->sample_period);
/*
* we currently do not support PERF_SAMPLE_GROUP on inherited counters
*/
if (attr->inherit && (attr->sample_type & PERF_SAMPLE_GROUP))
goto done;
switch (attr->type) {
case PERF_TYPE_RAW:
case PERF_TYPE_HARDWARE:
case PERF_TYPE_HW_CACHE:
pmu = hw_perf_counter_init(counter);
break;
case PERF_TYPE_SOFTWARE:
pmu = sw_perf_counter_init(counter);
break;
case PERF_TYPE_TRACEPOINT:
pmu = tp_perf_counter_init(counter);
break;
default:
break;
}
done:
err = 0;
if (!pmu)
err = -EINVAL;
else if (IS_ERR(pmu))
err = PTR_ERR(pmu);
if (err) {
if (counter->ns)
put_pid_ns(counter->ns);
kfree(counter);
return ERR_PTR(err);
}
counter->pmu = pmu;
if (!counter->parent) {
atomic_inc(&nr_counters);
if (counter->attr.mmap)
atomic_inc(&nr_mmap_counters);
if (counter->attr.comm)
atomic_inc(&nr_comm_counters);
}
return counter;
}
static int perf_copy_attr(struct perf_counter_attr __user *uattr,
struct perf_counter_attr *attr)
{
int ret;
u32 size;
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.
*/
if (size > sizeof(*attr)) {
unsigned long val;
unsigned long __user *addr;
unsigned long __user *end;
addr = PTR_ALIGN((void __user *)uattr + sizeof(*attr),
sizeof(unsigned long));
end = PTR_ALIGN((void __user *)uattr + size,
sizeof(unsigned long));
for (; addr < end; addr += sizeof(unsigned long)) {
ret = get_user(val, addr);
if (ret)
return ret;
if (val)
goto err_size;
}
}
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 || attr->__reserved_2 || attr->__reserved_3)
return -EINVAL;
if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))
return -EINVAL;
if (attr->read_format & ~(PERF_FORMAT_MAX-1))
return -EINVAL;
out:
return ret;
err_size:
put_user(sizeof(*attr), &uattr->size);
ret = -E2BIG;
goto out;
}
/**
* sys_perf_counter_open - open a performance counter, associate it to a task/cpu
*
* @attr_uptr: event type attributes for monitoring/sampling
* @pid: target pid
* @cpu: target cpu
* @group_fd: group leader counter fd
*/
SYSCALL_DEFINE5(perf_counter_open,
struct perf_counter_attr __user *, attr_uptr,
pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
{
struct perf_counter *counter, *group_leader;
struct perf_counter_attr attr;
struct perf_counter_context *ctx;
struct file *counter_file = NULL;
struct file *group_file = NULL;
int fput_needed = 0;
int fput_needed2 = 0;
int ret;
/* for future expandability... */
if (flags)
return -EINVAL;
ret = perf_copy_attr(attr_uptr, &attr);
if (ret)
return ret;
if (!attr.exclude_kernel) {
if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
return -EACCES;
}
if (attr.freq) {
if (attr.sample_freq > sysctl_perf_counter_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 counter to it):
*/
group_leader = NULL;
if (group_fd != -1) {
ret = -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;
}
counter = perf_counter_alloc(&attr, cpu, ctx, group_leader,
NULL, GFP_KERNEL);
ret = PTR_ERR(counter);
if (IS_ERR(counter))
goto err_put_context;
ret = anon_inode_getfd("[perf_counter]", &perf_fops, counter, 0);
if (ret < 0)
goto err_free_put_context;
counter_file = fget_light(ret, &fput_needed2);
if (!counter_file)
goto err_free_put_context;
counter->filp = counter_file;
WARN_ON_ONCE(ctx->parent_ctx);
mutex_lock(&ctx->mutex);
perf_install_in_context(ctx, counter, cpu);
++ctx->generation;
mutex_unlock(&ctx->mutex);
counter->owner = current;
get_task_struct(current);
mutex_lock(&current->perf_counter_mutex);
list_add_tail(&counter->owner_entry, &current->perf_counter_list);
mutex_unlock(&current->perf_counter_mutex);
fput_light(counter_file, fput_needed2);
out_fput:
fput_light(group_file, fput_needed);
return ret;
err_free_put_context:
kfree(counter);
err_put_context:
put_ctx(ctx);
goto out_fput;
}
/*
* inherit a counter from parent task to child task:
*/
static struct perf_counter *
inherit_counter(struct perf_counter *parent_counter,
struct task_struct *parent,
struct perf_counter_context *parent_ctx,
struct task_struct *child,
struct perf_counter *group_leader,
struct perf_counter_context *child_ctx)
{
struct perf_counter *child_counter;
/*
* Instead of creating recursive hierarchies of counters,
* we link inherited counters back to the original parent,
* which has a filp for sure, which we use as the reference
* count:
*/
if (parent_counter->parent)
parent_counter = parent_counter->parent;
child_counter = perf_counter_alloc(&parent_counter->attr,
parent_counter->cpu, child_ctx,
group_leader, parent_counter,
GFP_KERNEL);
if (IS_ERR(child_counter))
return child_counter;
get_ctx(child_ctx);
/*
* Make the child state follow the state of the parent counter,
* not its attr.disabled bit. We hold the parent's mutex,
* so we won't race with perf_counter_{en, dis}able_family.
*/
if (parent_counter->state >= PERF_COUNTER_STATE_INACTIVE)
child_counter->state = PERF_COUNTER_STATE_INACTIVE;
else
child_counter->state = PERF_COUNTER_STATE_OFF;
if (parent_counter->attr.freq)
child_counter->hw.sample_period = parent_counter->hw.sample_period;
/*
* Link it up in the child's context:
*/
add_counter_to_ctx(child_counter, child_ctx);
/*
* Get a reference to the parent filp - we will fput it
* when the child counter 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_counter->filp->f_count);
/*
* Link this into the parent counter's child list
*/
WARN_ON_ONCE(parent_counter->ctx->parent_ctx);
mutex_lock(&parent_counter->child_mutex);
list_add_tail(&child_counter->child_list, &parent_counter->child_list);
mutex_unlock(&parent_counter->child_mutex);
return child_counter;
}
static int inherit_group(struct perf_counter *parent_counter,
struct task_struct *parent,
struct perf_counter_context *parent_ctx,
struct task_struct *child,
struct perf_counter_context *child_ctx)
{
struct perf_counter *leader;
struct perf_counter *sub;
struct perf_counter *child_ctr;
leader = inherit_counter(parent_counter, parent, parent_ctx,
child, NULL, child_ctx);
if (IS_ERR(leader))
return PTR_ERR(leader);
list_for_each_entry(sub, &parent_counter->sibling_list, list_entry) {
child_ctr = inherit_counter(sub, parent, parent_ctx,
child, leader, child_ctx);
if (IS_ERR(child_ctr))
return PTR_ERR(child_ctr);
}
return 0;
}
static void sync_child_counter(struct perf_counter *child_counter,
struct task_struct *child)
{
struct perf_counter *parent_counter = child_counter->parent;
u64 child_val;
if (child_counter->attr.inherit_stat)
perf_counter_read_event(child_counter, child);
child_val = atomic64_read(&child_counter->count);
/*
* Add back the child's count to the parent's count:
*/
atomic64_add(child_val, &parent_counter->count);
atomic64_add(child_counter->total_time_enabled,
&parent_counter->child_total_time_enabled);
atomic64_add(child_counter->total_time_running,
&parent_counter->child_total_time_running);
/*
* Remove this counter from the parent's list
*/
WARN_ON_ONCE(parent_counter->ctx->parent_ctx);
mutex_lock(&parent_counter->child_mutex);
list_del_init(&child_counter->child_list);
mutex_unlock(&parent_counter->child_mutex);
/*
* Release the parent counter, if this was the last
* reference to it.
*/
fput(parent_counter->filp);
}
static void
__perf_counter_exit_task(struct perf_counter *child_counter,
struct perf_counter_context *child_ctx,
struct task_struct *child)
{
struct perf_counter *parent_counter;
update_counter_times(child_counter);
perf_counter_remove_from_context(child_counter);
parent_counter = child_counter->parent;
/*
* It can happen that parent exits first, and has counters
* that are still around due to the child reference. These
* counters need to be zapped - but otherwise linger.
*/
if (parent_counter) {
sync_child_counter(child_counter, child);
free_counter(child_counter);
}
}
/*
* When a child task exits, feed back counter values to parent counters.
*/
void perf_counter_exit_task(struct task_struct *child)
{
struct perf_counter *child_counter, *tmp;
struct perf_counter_context *child_ctx;
unsigned long flags;
if (likely(!child->perf_counter_ctxp))
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_counter_ctxp;
__perf_counter_task_sched_out(child_ctx);
/*
* Take the context lock here so that if find_get_context is
* reading child->perf_counter_ctxp, we wait until it has
* incremented the context's refcount before we do put_ctx below.
*/
spin_lock(&child_ctx->lock);
child->perf_counter_ctxp = NULL;
if (child_ctx->parent_ctx) {
/*
* This context is a clone; unclone it so it can't get
* swapped to another process while we're removing all
* the counters from it.
*/
put_ctx(child_ctx->parent_ctx);
child_ctx->parent_ctx = NULL;
}
spin_unlock(&child_ctx->lock);
local_irq_restore(flags);
/*
* We can recurse on the same lock type through:
*
* __perf_counter_exit_task()
* sync_child_counter()
* fput(parent_counter->filp)
* perf_release()
* mutex_lock(&ctx->mutex)
*
* But since its the parent context it won't be the same instance.
*/
mutex_lock_nested(&child_ctx->mutex, SINGLE_DEPTH_NESTING);
again:
list_for_each_entry_safe(child_counter, tmp, &child_ctx->counter_list,
list_entry)
__perf_counter_exit_task(child_counter, child_ctx, child);
/*
* If the last counter was a group counter, 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->counter_list))
goto again;
mutex_unlock(&child_ctx->mutex);
put_ctx(child_ctx);
}
/*
* free an unexposed, unused context as created by inheritance by
* init_task below, used by fork() in case of fail.
*/
void perf_counter_free_task(struct task_struct *task)
{
struct perf_counter_context *ctx = task->perf_counter_ctxp;
struct perf_counter *counter, *tmp;
if (!ctx)
return;
mutex_lock(&ctx->mutex);
again:
list_for_each_entry_safe(counter, tmp, &ctx->counter_list, list_entry) {
struct perf_counter *parent = counter->parent;
if (WARN_ON_ONCE(!parent))
continue;
mutex_lock(&parent->child_mutex);
list_del_init(&counter->child_list);
mutex_unlock(&parent->child_mutex);
fput(parent->filp);
list_del_counter(counter, ctx);
free_counter(counter);
}
if (!list_empty(&ctx->counter_list))
goto again;
mutex_unlock(&ctx->mutex);
put_ctx(ctx);
}
/*
* Initialize the perf_counter context in task_struct
*/
int perf_counter_init_task(struct task_struct *child)
{
struct perf_counter_context *child_ctx, *parent_ctx;
struct perf_counter_context *cloned_ctx;
struct perf_counter *counter;
struct task_struct *parent = current;
int inherited_all = 1;
int ret = 0;
child->perf_counter_ctxp = NULL;
mutex_init(&child->perf_counter_mutex);
INIT_LIST_HEAD(&child->perf_counter_list);
if (likely(!parent->perf_counter_ctxp))
return 0;
/*
* This is executed from the parent task context, so inherit
* counters that have been marked for cloning.
* First allocate and initialize a context for the child.
*/
child_ctx = kmalloc(sizeof(struct perf_counter_context), GFP_KERNEL);
if (!child_ctx)
return -ENOMEM;
__perf_counter_init_context(child_ctx, child);
child->perf_counter_ctxp = child_ctx;
get_task_struct(child);
/*
* 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_rcu(counter, &parent_ctx->event_list, event_entry) {
if (counter != counter->group_leader)
continue;
if (!counter->attr.inherit) {
inherited_all = 0;
continue;
}
ret = inherit_group(counter, parent, parent_ctx,
child, child_ctx);
if (ret) {
inherited_all = 0;
break;
}
}
if (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 counters 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 __cpuinit perf_counter_init_cpu(int cpu)
{
struct perf_cpu_context *cpuctx;
cpuctx = &per_cpu(perf_cpu_context, cpu);
__perf_counter_init_context(&cpuctx->ctx, NULL);
spin_lock(&perf_resource_lock);
cpuctx->max_pertask = perf_max_counters - perf_reserved_percpu;
spin_unlock(&perf_resource_lock);
hw_perf_counter_setup(cpu);
}
#ifdef CONFIG_HOTPLUG_CPU
static void __perf_counter_exit_cpu(void *info)
{
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_counter_context *ctx = &cpuctx->ctx;
struct perf_counter *counter, *tmp;
list_for_each_entry_safe(counter, tmp, &ctx->counter_list, list_entry)
__perf_counter_remove_from_context(counter);
}
static void perf_counter_exit_cpu(int cpu)
{
struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
struct perf_counter_context *ctx = &cpuctx->ctx;
mutex_lock(&ctx->mutex);
smp_call_function_single(cpu, __perf_counter_exit_cpu, NULL, 1);
mutex_unlock(&ctx->mutex);
}
#else
static inline void perf_counter_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_counter_init_cpu(cpu);
break;
case CPU_DOWN_PREPARE:
case CPU_DOWN_PREPARE_FROZEN:
perf_counter_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_counter_init(void)
{
perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_UP_PREPARE,
(void *)(long)smp_processor_id());
register_cpu_notifier(&perf_cpu_nb);
}
static ssize_t perf_show_reserve_percpu(struct sysdev_class *class, char *buf)
{
return sprintf(buf, "%d\n", perf_reserved_percpu);
}
static ssize_t
perf_set_reserve_percpu(struct sysdev_class *class,
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_counters)
return -EINVAL;
spin_lock(&perf_resource_lock);
perf_reserved_percpu = val;
for_each_online_cpu(cpu) {
cpuctx = &per_cpu(perf_cpu_context, cpu);
spin_lock_irq(&cpuctx->ctx.lock);
mpt = min(perf_max_counters - cpuctx->ctx.nr_counters,
perf_max_counters - perf_reserved_percpu);
cpuctx->max_pertask = mpt;
spin_unlock_irq(&cpuctx->ctx.lock);
}
spin_unlock(&perf_resource_lock);
return count;
}
static ssize_t perf_show_overcommit(struct sysdev_class *class, char *buf)
{
return sprintf(buf, "%d\n", perf_overcommit);
}
static ssize_t
perf_set_overcommit(struct sysdev_class *class, 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_counters",
};
static int __init perf_counter_sysfs_init(void)
{
return sysfs_create_group(&cpu_sysdev_class.kset.kobj,
&perfclass_attr_group);
}
device_initcall(perf_counter_sysfs_init);
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