Commit c4fcc7d1 authored by Kyle Huey's avatar Kyle Huey Committed by Ingo Molnar
Browse files

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



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: default avatarKyle Huey <khuey@kylehuey.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarSong Liu <song@kernel.org>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240412015019.7060-7-khuey@kylehuey.com
parent 76f6d588

kernel/events/core.c

+4 −2
Original line number Diff line number Diff line
@@ -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
@@ -9726,7 +9729,6 @@ 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);



	if (*perf_event_fasync(event) && event->pending_kill) {