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[76.126.33.191]) by smtp.gmail.com with ESMTPSA id e11-20020a170902b78b00b001d2ffeac9d3sm3300623pls.186.2023.12.10.20.55.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 10 Dec 2023 20:55:57 -0800 (PST) From: Kyle Huey X-Google-Original-From: Kyle Huey To: Kyle Huey , linux-kernel@vger.kernel.org, Andrii Nakryiko , Jiri Olsa , Namhyung Kim , Marco Elver , Yonghong Song Cc: Robert O'Callahan , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Ian Rogers , Adrian Hunter , linux-perf-users@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH v3 3/4] perf/bpf: Allow a bpf program to suppress all sample side effects Date: Sun, 10 Dec 2023 20:55:42 -0800 Message-Id: <20231211045543.31741-4-khuey@kylehuey.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231211045543.31741-1-khuey@kylehuey.com> References: <20231211045543.31741-1-khuey@kylehuey.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 Acked-by: Song Liu --- kernel/events/core.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 54f6372d2634..d6093fe893c8 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9541,6 +9541,11 @@ static int __perf_event_overflow(struct perf_event *= event, =20 ret =3D __perf_event_account_interrupt(event, throttle); =20 +#ifdef CONFIG_BPF_SYSCALL + if (event->prog && !bpf_overflow_handler(event, data, regs)) + return ret; +#endif + /* * XXX event_limit might not quite work as expected on inherited * events @@ -9590,10 +9595,7 @@ static int __perf_event_overflow(struct perf_event *= event, irq_work_queue(&event->pending_irq); } =20 -#ifdef CONFIG_BPF_SYSCALL - if (!(event->prog && !bpf_overflow_handler(event, data, regs))) -#endif - READ_ONCE(event->overflow_handler)(event, data, regs); + READ_ONCE(event->overflow_handler)(event, data, regs); =20 if (*perf_event_fasync(event) && event->pending_kill) { event->pending_wakeup =3D 1; --=20 2.34.1