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kernel-fxtec-pro1x/kernel/perf_counter.c
Peter Zijlstra 974802eaa1 perf_counter: Add forward/backward attribute ABI compatibility 
Provide for means of extending the perf_counter_attr in a 'natural' way.

We allow growing the structure by appending fields at the end by specifying
the full structure size inside it.

When a new kernel sees a smaller (old) structure, it will 0 pad the tail.
When an old kernel sees a larger (new) structure, it will verify the tail
consists of 0s, otherwise fail.

If we fail due to a size-mismatch, we return -E2BIG and write the kernel's
native attribe size back into the provided structure.

Furthermore, add some attribute verification, so that we'll fail counter
creation when unknown bits are present (PERF_SAMPLE, PERF_FORMAT, or in
the __reserved fields).

(This ABI detail is introduced while keeping the existing syscall ABI.)

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-06-12 14:28:52 +02:00

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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)
{
atomic_inc(&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;
}
}
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;
get_ctx(ctx);
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++;
}
/*
* 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--;
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;
}
/*
* 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;
}
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);
atomic_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 __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,
__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 */
}
/*
* Get an extra reference before dropping the lock so that
* this context won't get freed if the task exits.
*/
get_ctx(ctx);
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);
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[3];
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);
}
static void perf_counter_for_each_sibling(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;
func(counter);
list_for_each_entry(sibling, &counter->sibling_list, list_entry)
func(sibling);
mutex_unlock(&ctx->mutex);
}
/*
* 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 *child;
WARN_ON_ONCE(counter->ctx->parent_ctx);
mutex_lock(&counter->child_mutex);
perf_counter_for_each_sibling(counter, func);
list_for_each_entry(child, &counter->child_list, child_list)
perf_counter_for_each_sibling(child, func);
mutex_unlock(&counter->child_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;
}
/*
* 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 = counter->hw.idx;
userpg->offset = atomic64_read(&counter->count);
if (counter->state == PERF_COUNTER_STATE_ACTIVE)
userpg->offset -= atomic64_read(&counter->hw.prev_count);
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;
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;
vmf->page = virt_to_page(data->data_pages[nr]);
}
get_page(vmf->page);
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_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);
free_page((unsigned long)data->user_page);
for (i = 0; i < data->nr_pages; i++)
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,
};
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) || (vma->vm_flags & VM_WRITE))
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;
unlock:
mutex_unlock(&counter->mmap_mutex);
vma->vm_flags &= ~VM_MAYWRITE;
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 overflow;
int locked;
unsigned long flags;
};
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 int perf_output_begin(struct perf_output_handle *handle,
struct perf_counter *counter, unsigned int size,
int nmi, int overflow)
{
struct perf_mmap_data *data;
unsigned int offset, head;
/*
* 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->overflow = overflow;
if (!data->nr_pages)
goto fail;
perf_output_lock(handle);
do {
offset = head = atomic_long_read(&data->head);
head += size;
} 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);
return 0;
fail:
perf_output_wakeup(handle);
out:
rcu_read_unlock();
return -ENOSPC;
}
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 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->overflow && 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);
}
/*
* 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.
*/
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 pt_regs *regs, u64 addr)
{
struct perf_sample_data data = {
.regs = regs,
.addr = addr,
.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 pt_regs *regs, u64 addr)
{
int neg = atomic64_add_negative(nr, &counter->hw.count);
if (counter->hw.sample_period && !neg && regs)
perf_swcounter_overflow(counter, nmi, regs, addr);
}
static void perf_swcounter_ctx_event(struct perf_counter_context *ctx,
enum perf_type_id type, u32 event,
u64 nr, int nmi, struct pt_regs *regs,
u64 addr)
{
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, regs))
perf_swcounter_add(counter, nr, nmi, regs, addr);
}
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 __perf_swcounter_event(enum perf_type_id type, u32 event,
u64 nr, int nmi, struct pt_regs *regs,
u64 addr)
{
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, regs, addr);
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, regs, addr);
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)
{
__perf_swcounter_event(PERF_TYPE_SOFTWARE, event, nr, nmi, regs, addr);
}
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,
};
/*
* Software counter: cpu migrations
*/
void perf_counter_task_migration(struct task_struct *task, int cpu)
{
struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
struct perf_counter_context *ctx;
perf_swcounter_ctx_event(&cpuctx->ctx, PERF_TYPE_SOFTWARE,
PERF_COUNT_SW_CPU_MIGRATIONS,
1, 1, NULL, 0);
ctx = perf_pin_task_context(task);
if (ctx) {
perf_swcounter_ctx_event(ctx, PERF_TYPE_SOFTWARE,
PERF_COUNT_SW_CPU_MIGRATIONS,
1, 1, NULL, 0);
perf_unpin_context(ctx);
}
}
#ifdef CONFIG_EVENT_PROFILE
void perf_tpcounter_event(int event_id)
{
struct pt_regs *regs = get_irq_regs();
if (!regs)
regs = task_pt_regs(current);
__perf_swcounter_event(PERF_TYPE_TRACEPOINT, event_id, 1, 1, regs, 0);
}
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
static const struct pmu *sw_perf_counter_init(struct perf_counter *counter)
{
const struct pmu *pmu = NULL;
/*
* 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 (counter->attr.config) {
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:
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,
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->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;
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,
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, 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);
child_counter->parent = parent_counter;
/*
* inherit into child's child as well:
*/
child_counter->attr.inherit = 1;
/*
* 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 perf_counter *parent_counter)
{
u64 child_val;
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 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, parent_counter);
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);
/*
* 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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