From patchwork Thu Jun 27 15:23:38 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mathieu Desnoyers X-Patchwork-Id: 13714675 Received: from smtpout.efficios.com (smtpout.efficios.com [167.114.26.122]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8DD76198E96; Thu, 27 Jun 2024 15:23:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=167.114.26.122 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719501794; cv=none; b=Kkz6n6yRWR0xUZopHcoknnK4KwGGaXWpBJFLS31Tb+OuPBj2USSOOb5ie2we7EVlLsOGkeWc8ODt5hBxyGsNnYqgcsLYUOAQvjpnWLIovP3SUe05nilzCiKBdWwe9n2u7IBhhk9h+rzXZFgX7AQqN6k0qH4yKTgiVreraOjCrvQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719501794; c=relaxed/simple; bh=Ii+cxjz0MLUIaEg5tcYbEKz1AeI5UWrbwUMe27azAqI=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=kqe/xkHr9aXKBQPHIedckraTEAVHHeD3tadg882XmGoi3XbAUDV1CZa+NuaF9qL0WZj6+KbPp9WSO4Wgx/q6AkeVvdP0GeiSD3aVhaa90IZOGZ6S/bv0gkmV8ghCTtQzO65E9WN20mwI1IeQ4R0njMq4S1ylvV2GcCst098zQb4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com; spf=pass smtp.mailfrom=efficios.com; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b=AHE8/1jC; arc=none smtp.client-ip=167.114.26.122 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=efficios.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="AHE8/1jC" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1719501790; bh=Ii+cxjz0MLUIaEg5tcYbEKz1AeI5UWrbwUMe27azAqI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AHE8/1jCzBX/zcC/WTATZx87w4d2KYhk0D6hXpzkWDJW2Ioa8dTzc0Zy9PaO6hzpT 3RpCXw6/s8Ux0qbErahEIlIwO+6NR+t0+Q2QuvduOyhp6OBdBPWOkuGZ2sLIJay6xR oqANUa09gBULBLWTi0Lwncbk28/bGExSoCQtHk4MuWmas8GGOw5UDgLyKN1G/kO2Pj 1Pt2Bu1Il/sECk2fCdEveBM0OPEU+ioWD7JqIaBnE3JKpGtmo3PIUshSlesgQJQySj gHY6M3n7AxUx3Ugq2+/xhnpd5ia3qYUYiFNx8wU7TjUdhGuc1VFMG4I9GXno2k5s1f hACtg6uRkofjw== Received: from thinkos.internal.efficios.com (192-222-143-198.qc.cable.ebox.net [192.222.143.198]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4W92Q61sZNz183P; Thu, 27 Jun 2024 11:23:10 -0400 (EDT) From: Mathieu Desnoyers To: Steven Rostedt , Masami Hiramatsu Cc: linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, Mathieu Desnoyers , Peter Zijlstra , Alexei Starovoitov , Yonghong Song , "Paul E . McKenney" , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , bpf@vger.kernel.org, Joel Fernandes , Michael Jeanson Subject: [PATCH v5 6/8] tracing/bpf-trace: Add support for faultable tracepoints Date: Thu, 27 Jun 2024 11:23:38 -0400 Message-Id: <20240627152340.82413-7-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240627152340.82413-1-mathieu.desnoyers@efficios.com> References: <20240627152340.82413-1-mathieu.desnoyers@efficios.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In preparation for converting system call enter/exit instrumentation into faultable tracepoints, make sure that bpf can handle registering to such tracepoints by explicitly disabling preemption within the bpf tracepoint probes to respect the current expectations within bpf tracing code. This change does not yet allow bpf to take page faults per se within its probe, but allows its existing probes to connect to faultable tracepoints. Link: https://lore.kernel.org/lkml/20231002202531.3160-1-mathieu.desnoyers@efficios.com/ Co-developed-by: Michael Jeanson Signed-off-by: Mathieu Desnoyers Signed-off-by: Michael Jeanson Cc: Steven Rostedt Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Alexei Starovoitov Cc: Yonghong Song Cc: Paul E. McKenney Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Mark Rutland Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Namhyung Kim Cc: bpf@vger.kernel.org Cc: Joel Fernandes --- Changes since v4: - Use DEFINE_INACTIVE_GUARD. - Add brackets to multiline 'if' statements. --- include/trace/bpf_probe.h | 20 ++++++++++++++++---- kernel/trace/bpf_trace.c | 12 +++++++++--- 2 files changed, 25 insertions(+), 7 deletions(-) diff --git a/include/trace/bpf_probe.h b/include/trace/bpf_probe.h index e609cd7da47e..96c1269dd88c 100644 --- a/include/trace/bpf_probe.h +++ b/include/trace/bpf_probe.h @@ -42,17 +42,29 @@ /* tracepoints with more than 12 arguments will hit build error */ #define CAST_TO_U64(...) CONCATENATE(__CAST, COUNT_ARGS(__VA_ARGS__))(__VA_ARGS__) -#define __BPF_DECLARE_TRACE(call, proto, args) \ +#define __BPF_DECLARE_TRACE(call, proto, args, tp_flags) \ static notrace void \ __bpf_trace_##call(void *__data, proto) \ { \ struct bpf_prog *prog = __data; \ + \ + DEFINE_INACTIVE_GUARD(preempt_notrace, bpf_trace_guard); \ + \ + if ((tp_flags) & TRACEPOINT_MAY_FAULT) { \ + might_fault(); \ + activate_guard(preempt_notrace, bpf_trace_guard)(); \ + } \ + \ CONCATENATE(bpf_trace_run, COUNT_ARGS(args))(prog, CAST_TO_U64(args)); \ } #undef DECLARE_EVENT_CLASS #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \ - __BPF_DECLARE_TRACE(call, PARAMS(proto), PARAMS(args)) + __BPF_DECLARE_TRACE(call, PARAMS(proto), PARAMS(args), 0) + +#undef DECLARE_EVENT_CLASS_MAY_FAULT +#define DECLARE_EVENT_CLASS_MAY_FAULT(call, proto, args, tstruct, assign, print) \ + __BPF_DECLARE_TRACE(call, PARAMS(proto), PARAMS(args), TRACEPOINT_MAY_FAULT) /* * This part is compiled out, it is only here as a build time check @@ -106,13 +118,13 @@ static inline void bpf_test_buffer_##call(void) \ #undef DECLARE_TRACE #define DECLARE_TRACE(call, proto, args) \ - __BPF_DECLARE_TRACE(call, PARAMS(proto), PARAMS(args)) \ + __BPF_DECLARE_TRACE(call, PARAMS(proto), PARAMS(args), 0) \ __DEFINE_EVENT(call, call, PARAMS(proto), PARAMS(args), 0) #undef DECLARE_TRACE_WRITABLE #define DECLARE_TRACE_WRITABLE(call, proto, args, size) \ __CHECK_WRITABLE_BUF_SIZE(call, PARAMS(proto), PARAMS(args), size) \ - __BPF_DECLARE_TRACE(call, PARAMS(proto), PARAMS(args)) \ + __BPF_DECLARE_TRACE(call, PARAMS(proto), PARAMS(args), 0) \ __DEFINE_EVENT(call, call, PARAMS(proto), PARAMS(args), size) #include TRACE_INCLUDE(TRACE_INCLUDE_FILE) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 192de33d961f..873b0e885677 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2443,9 +2443,15 @@ static int __bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog * if (prog->aux->max_tp_access > btp->writable_size) return -EINVAL; - return tracepoint_probe_register_prio_flags(tp, (void *)btp->bpf_func, - prog, TRACEPOINT_DEFAULT_PRIO, - TRACEPOINT_MAY_EXIST); + if (tp->flags & TRACEPOINT_MAY_FAULT) { + return tracepoint_probe_register_prio_flags(tp, (void *)btp->bpf_func, + prog, TRACEPOINT_DEFAULT_PRIO, + TRACEPOINT_MAY_EXIST | TRACEPOINT_MAY_FAULT); + } else { + return tracepoint_probe_register_prio_flags(tp, (void *)btp->bpf_func, + prog, TRACEPOINT_DEFAULT_PRIO, + TRACEPOINT_MAY_EXIST); + } } int bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog *prog)