diff options
| -rw-r--r-- | include/linux/perf_event.h | 10 | ||||
| -rw-r--r-- | kernel/events/core.c | 78 |
2 files changed, 88 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 2027809433b3..092a0e8a479a 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -641,6 +641,8 @@ extern int perf_event_init_task(struct task_struct *child); extern void perf_event_exit_task(struct task_struct *child); extern void perf_event_free_task(struct task_struct *task); extern void perf_event_delayed_put(struct task_struct *task); +extern struct perf_event *perf_event_get(unsigned int fd); +extern const struct perf_event_attr *perf_event_attrs(struct perf_event *event); extern void perf_event_print_debug(void); extern void perf_pmu_disable(struct pmu *pmu); extern void perf_pmu_enable(struct pmu *pmu); @@ -659,6 +661,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, void *context); extern void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu); +extern u64 perf_event_read_local(struct perf_event *event); extern u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running); @@ -979,6 +982,12 @@ static inline int perf_event_init_task(struct task_struct *child) { return 0; } static inline void perf_event_exit_task(struct task_struct *child) { } static inline void perf_event_free_task(struct task_struct *task) { } static inline void perf_event_delayed_put(struct task_struct *task) { } +static inline struct perf_event *perf_event_get(unsigned int fd) { return ERR_PTR(-EINVAL); } +static inline const struct perf_event_attr *perf_event_attrs(struct perf_event *event) +{ + return ERR_PTR(-EINVAL); +} +static inline u64 perf_event_read_local(struct perf_event *event) { return -EINVAL; } static inline void perf_event_print_debug(void) { } static inline int perf_event_task_disable(void) { return -EINVAL; } static inline int perf_event_task_enable(void) { return -EINVAL; } @@ -1011,6 +1020,7 @@ static inline void perf_event_enable(struct perf_event *event) { } static inline void perf_event_disable(struct perf_event *event) { } static inline int __perf_event_disable(void *info) { return -1; } static inline void perf_event_task_tick(void) { } +static inline int perf_event_release_kernel(struct perf_event *event) { return 0; } #endif #if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_NO_HZ_FULL) diff --git a/kernel/events/core.c b/kernel/events/core.c index d3dae3419b99..e2c6a8886d4d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3212,6 +3212,59 @@ static inline u64 perf_event_count(struct perf_event *event) return __perf_event_count(event); } +/* + * NMI-safe method to read a local event, that is an event that + * is: + * - either for the current task, or for this CPU + * - does not have inherit set, for inherited task events + * will not be local and we cannot read them atomically + * - must not have a pmu::count method + */ +u64 perf_event_read_local(struct perf_event *event) +{ + unsigned long flags; + u64 val; + + /* + * Disabling interrupts avoids all counter scheduling (context + * switches, timer based rotation and IPIs). + */ + local_irq_save(flags); + + /* If this is a per-task event, it must be for current */ + WARN_ON_ONCE((event->attach_state & PERF_ATTACH_TASK) && + event->hw.target != current); + + /* If this is a per-CPU event, it must be for this CPU */ + WARN_ON_ONCE(!(event->attach_state & PERF_ATTACH_TASK) && + event->cpu != smp_processor_id()); + + /* + * It must not be an event with inherit set, we cannot read + * all child counters from atomic context. + */ + WARN_ON_ONCE(event->attr.inherit); + + /* + * It must not have a pmu::count method, those are not + * NMI safe. + */ + WARN_ON_ONCE(event->pmu->count); + + /* + * If the event is currently on this CPU, its either a per-task event, + * or local to this CPU. Furthermore it means its ACTIVE (otherwise + * oncpu == -1). + */ + if (event->oncpu == smp_processor_id()) + event->pmu->read(event); + + val = local64_read(&event->count); + local_irq_restore(flags); + + return val; +} + static u64 perf_event_read(struct perf_event *event) { /* @@ -8574,6 +8627,31 @@ void perf_event_delayed_put(struct task_struct *task) WARN_ON_ONCE(task->perf_event_ctxp[ctxn]); } +struct perf_event *perf_event_get(unsigned int fd) +{ + int err; + struct fd f; + struct perf_event *event; + + err = perf_fget_light(fd, &f); + if (err) + return ERR_PTR(err); + + event = f.file->private_data; + atomic_long_inc(&event->refcount); + fdput(f); + + return event; +} + +const struct perf_event_attr *perf_event_attrs(struct perf_event *event) +{ + if (!event) + return ERR_PTR(-EINVAL); + + return &event->attr; +} + /* * inherit a event from parent task to child task: */ |