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perf/bpf: Allow a BPF program to suppress all sample side effects

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Returning zero from a BPF program attached to a perf event already
suppresses any data output. Return early from __perf_event_overflow() in
this case so it will also suppress event_limit accounting, SIGTRAP
generation, and F_ASYNC signalling.

Signed-off-by: Kyle Huey <khuey@kylehuey.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240412015019.7060-7-khuey@kylehuey.com
This commit is contained in:
Kyle Huey 2024-04-11 18:50:18 -07:00 committed by Ingo Molnar
parent 76f6d58845
commit c4fcc7d1f4
1 changed files with 4 additions and 2 deletions
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6
kernel/events/core.c
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@ -9677,6 +9677,9 @@ static int __perf_event_overflow(struct perf_event *event,
ret = __perf_event_account_interrupt(event, throttle);
if (event->prog && !bpf_overflow_handler(event, data, regs))
return ret;
/*
* XXX event_limit might not quite work as expected on inherited
* events
@ -9726,8 +9729,7 @@ static int __perf_event_overflow(struct perf_event *event,
irq_work_queue(&event->pending_irq);
}
if (!(event->prog && !bpf_overflow_handler(event, data, regs)))
READ_ONCE(event->overflow_handler)(event, data, regs);
READ_ONCE(event->overflow_handler)(event, data, regs);
if (*perf_event_fasync(event) && event->pending_kill) {
event->pending_wakeup = 1;