perf/core: Provide a kernel-internal interface to recalibrate event period
Currently, perf_event_period() is used by user tools via ioctl. Based on naming convention, exporting perf_event_period() for kernel users (such as KVM) who may recalibrate the event period for their assigned counter according to their requirements. The perf_event_period() is an external accessor, just like the perf_event_{en,dis}able() and should thus use perf_event_ctx_lock(). Suggested-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Like Xu <like.xu@linux.intel.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -1336,6 +1336,7 @@ extern void perf_event_disable_local(struct perf_event *event);
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extern void perf_event_disable_inatomic(struct perf_event *event);
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extern void perf_event_task_tick(void);
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extern int perf_event_account_interrupt(struct perf_event *event);
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extern int perf_event_period(struct perf_event *event, u64 value);
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#else /* !CONFIG_PERF_EVENTS: */
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static inline void *
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perf_aux_output_begin(struct perf_output_handle *handle,
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@ -1415,6 +1416,10 @@ static inline void perf_event_disable(struct perf_event *event) { }
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static inline int __perf_event_disable(void *info) { return -1; }
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static inline void perf_event_task_tick(void) { }
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static inline int perf_event_release_kernel(struct perf_event *event) { return 0; }
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static inline int perf_event_period(struct perf_event *event, u64 value)
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{
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return -EINVAL;
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}
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#endif
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#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
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@ -5106,16 +5106,11 @@ static int perf_event_check_period(struct perf_event *event, u64 value)
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return event->pmu->check_period(event, value);
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}
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static int perf_event_period(struct perf_event *event, u64 __user *arg)
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static int _perf_event_period(struct perf_event *event, u64 value)
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{
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u64 value;
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if (!is_sampling_event(event))
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return -EINVAL;
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if (copy_from_user(&value, arg, sizeof(value)))
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return -EFAULT;
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if (!value)
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return -EINVAL;
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@ -5133,6 +5128,19 @@ static int perf_event_period(struct perf_event *event, u64 __user *arg)
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return 0;
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}
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int perf_event_period(struct perf_event *event, u64 value)
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{
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struct perf_event_context *ctx;
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int ret;
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ctx = perf_event_ctx_lock(event);
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ret = _perf_event_period(event, value);
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perf_event_ctx_unlock(event, ctx);
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return ret;
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}
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EXPORT_SYMBOL_GPL(perf_event_period);
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static const struct file_operations perf_fops;
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static inline int perf_fget_light(int fd, struct fd *p)
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@ -5176,8 +5184,14 @@ static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned lon
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return _perf_event_refresh(event, arg);
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case PERF_EVENT_IOC_PERIOD:
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return perf_event_period(event, (u64 __user *)arg);
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{
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u64 value;
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if (copy_from_user(&value, (u64 __user *)arg, sizeof(value)))
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return -EFAULT;
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return _perf_event_period(event, value);
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}
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case PERF_EVENT_IOC_ID:
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{
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u64 id = primary_event_id(event);
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