From nobody Thu Dec 18 18:05:30 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 01F7FC2BB3F for ; Mon, 20 Nov 2023 20:54:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231374AbjKTUyu (ORCPT ); Mon, 20 Nov 2023 15:54:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230296AbjKTUys (ORCPT ); Mon, 20 Nov 2023 15:54:48 -0500 Received: from smtpout.efficios.com (unknown [IPv6:2607:5300:203:b2ee::31e5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E51F2CF; Mon, 20 Nov 2023 12:54:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1700513680; bh=T7Nr4r/6B9r8V/IXWfdEL5nzZ2OVp6Lt4IjgQKAxAJM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oLQ5Jv2JPcwEa+icp0BZjOHxsNfVcK1LCUYVoZE6SmDGbC4oUBOBiPOLXxmGi1tSE TTU0pgrcELQpQZNXJeXv4CTpqZFJHcp1M9apNGovdE+d3p5eYKVkUlA5EG5cyxu5UL p4gsrZ6RFVRKcyBBpvaCkTTadHxj81t2Brg5uj9sDR/R7sEBe4EPIGcIFDUV8IfDAp a70A5F4j9Fny9L/8f8YtOA7slJQRCi4yiVbOj8gbledJttrdjEBXKMSuX1j02u9uTe eMkqMQT8uVVGDjAWOv6dbzwU4Ez0kp/RrMECEjt+0iB337XZoXPL+CrnboG4fquTxp QeQa34EMelXAQ== Received: from localhost.localdomain (192-222-143-198.qc.cable.ebox.net [192.222.143.198]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4SZ0B80w7Zz1cy0; Mon, 20 Nov 2023 15:54:40 -0500 (EST) From: Mathieu Desnoyers To: Steven Rostedt , Masami Hiramatsu Cc: linux-kernel@vger.kernel.org, Mathieu Desnoyers , Michael Jeanson , 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 Subject: [PATCH v4 3/5] tracing/bpf-trace: add support for faultable tracepoints Date: Mon, 20 Nov 2023 15:54:16 -0500 Message-Id: <20231120205418.334172-4-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20231120205418.334172-1-mathieu.desnoyers@efficios.com> References: <20231120205418.334172-1-mathieu.desnoyers@efficios.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" 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 --- include/trace/bpf_probe.h | 21 +++++++++++++++++---- kernel/trace/bpf_trace.c | 11 ++++++++--- 2 files changed, 25 insertions(+), 7 deletions(-) diff --git a/include/trace/bpf_probe.h b/include/trace/bpf_probe.h index e609cd7da47e..dd4b42715e5d 100644 --- a/include/trace/bpf_probe.h +++ b/include/trace/bpf_probe.h @@ -42,17 +42,30 @@ /* tracepoints with more than 12 arguments will hit build error */ #define CAST_TO_U64(...) CONCATENATE(__CAST, COUNT_ARGS(__VA_ARGS__))(__VA= _ARGS__) =20 -#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 =3D __data; \ + \ + if ((tp_flags) & TRACEPOINT_MAY_FAULT) { \ + might_fault(); \ + preempt_disable_notrace(); \ + } \ + \ CONCATENATE(bpf_trace_run, COUNT_ARGS(args))(prog, CAST_TO_U64(args)); \ + \ + if ((tp_flags) & TRACEPOINT_MAY_FAULT) \ + preempt_enable_notrace(); \ } =20 #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_FAU= LT) =20 /* * This part is compiled out, it is only here as a build time check @@ -106,13 +119,13 @@ static inline void bpf_test_buffer_##call(void) \ =20 #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) =20 #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) =20 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 344a41873445..1eb770dafa8a 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2368,9 +2368,14 @@ 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; =20 - 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); } =20 int bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog *pro= g) --=20 2.25.1