From nobody Wed Nov 27 18:35:27 2024 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 8E29B18EB0; Wed, 9 Oct 2024 01:09:26 +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=1728436169; cv=none; b=pmPx10l43Z+TbUY0NT2xsQYMKjyzFIYD4aoZHE+n9QWeaXHUq/HMNUJ8oT3oH6g73vtscweeaA9TKECBuGEPdd0N22WLgA83UEe+56K8FrrHdxN0NOP00cZCtXkiPeFw9Y7Ddr4wj8ezwphLR6ejHUQNlzTGYMLBgQuAlkeSgJc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728436169; c=relaxed/simple; bh=EQy9nBwfdBBTeUIVwr6GtveugPYJbTrmr+BnE/E2ovw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Pg2iH9HyL4YIVLE6zrf9FaFuIQ2swMsDx2P8e2lQCTdDWIY8/wA00k9YJIQ1jEIxYr6sSl37XdLbICHDhOQTMKc+KdAgm8ez3SVwkvyQzlDEiUHHS58cS+5erD2bxiXHbS2Nn1Tw6FmRG+n+XglfSbee/LRDHlEOEl419AxLiZs= 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=bMMWa5uG; 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="bMMWa5uG" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1728436166; bh=EQy9nBwfdBBTeUIVwr6GtveugPYJbTrmr+BnE/E2ovw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bMMWa5uGJ6R6Ld2b3iGkJjwsWxGbxGTc9j6PeRrDh4pdFRMJN0/+5RdvTlu13+TvT dNZGwAnSoaZ1hFSer1+VUr6q9zJofaKrSOlH/vCP39fJZ9MITjMP1JYsrZHDWS2mni CJqSL2X+o5euqaoNz8YDI9Fk2Xzemp479l3njRxxDipshFkvHS2QNs+Fw3Q2YsdLyl xL/V+rtrUcjQdR5cCR/rSklj2cAtSNIL8xEcqGTQfjnLisDzmgcunJ56yWMvoxAszX BIyF0n4pGhgDo/t+U7snKJIP8aESKU17RKzjsk5On/dMeMDayYFe0g0kdgO90AJfn9 vexk9oGWHOneA== Received: from thinkos.internal.efficios.com (unknown [IPv6:2606:6d00:100:4000:cacb:9855:de1f:ded2]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4XNZY14Qg7zS7S; Tue, 8 Oct 2024 21:09:25 -0400 (EDT) From: Mathieu Desnoyers To: Steven Rostedt , Masami Hiramatsu Cc: 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 , Namhyung Kim , Andrii Nakryiko , bpf@vger.kernel.org, Joel Fernandes , linux-trace-kernel@vger.kernel.org, Michael Jeanson Subject: [PATCH v4 2/8] tracing/ftrace: disable preemption in syscall probe Date: Tue, 8 Oct 2024 21:07:12 -0400 Message-Id: <20241009010718.2050182-3-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20241009010718.2050182-1-mathieu.desnoyers@efficios.com> References: <20241009010718.2050182-1-mathieu.desnoyers@efficios.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In preparation for allowing system call enter/exit instrumentation to handle page faults, make sure that ftrace can handle this change by explicitly disabling preemption within the ftrace system call tracepoint probes to respect the current expectations within ftrace ring buffer code. This change does not yet allow ftrace to take page faults per se within its probe, but allows its existing probes to adapt to the upcoming change. Signed-off-by: Mathieu Desnoyers Acked-by: Masami Hiramatsu (Google) Cc: 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: Namhyung Kim Cc: Andrii Nakryiko Cc: bpf@vger.kernel.org Cc: Joel Fernandes --- Changes since v3: - Do not use guard() for single line function, based on feedback from Steven. --- include/trace/trace_events.h | 39 ++++++++++++++++++++++++++++------- kernel/trace/trace_syscalls.c | 12 +++++++++++ 2 files changed, 44 insertions(+), 7 deletions(-) diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h index 8bcbb9ee44de..63071aa5923d 100644 --- a/include/trace/trace_events.h +++ b/include/trace/trace_events.h @@ -263,6 +263,9 @@ static struct trace_event_fields trace_event_fields_##c= all[] =3D { \ tstruct \ {} }; =20 +#undef DECLARE_EVENT_SYSCALL_CLASS +#define DECLARE_EVENT_SYSCALL_CLASS DECLARE_EVENT_CLASS + #undef DEFINE_EVENT_PRINT #define DEFINE_EVENT_PRINT(template, name, proto, args, print) =20 @@ -396,11 +399,11 @@ static inline notrace int trace_event_get_offsets_##c= all( \ =20 #include "stages/stage6_event_callback.h" =20 -#undef DECLARE_EVENT_CLASS -#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \ - \ + +#undef __DECLARE_EVENT_CLASS +#define __DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \ static notrace void \ -trace_event_raw_event_##call(void *__data, proto) \ +do_trace_event_raw_event_##call(void *__data, proto) \ { \ struct trace_event_file *trace_file =3D __data; \ struct trace_event_data_offsets_##call __maybe_unused __data_offsets;\ @@ -425,15 +428,35 @@ trace_event_raw_event_##call(void *__data, proto) \ \ trace_event_buffer_commit(&fbuffer); \ } + +#undef DECLARE_EVENT_CLASS +#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \ +__DECLARE_EVENT_CLASS(call, PARAMS(proto), PARAMS(args), PARAMS(tstruct), \ + PARAMS(assign), PARAMS(print)) \ +static notrace void \ +trace_event_raw_event_##call(void *__data, proto) \ +{ \ + do_trace_event_raw_event_##call(__data, args); \ +} + +#undef DECLARE_EVENT_SYSCALL_CLASS +#define DECLARE_EVENT_SYSCALL_CLASS(call, proto, args, tstruct, assign, pr= int) \ +__DECLARE_EVENT_CLASS(call, PARAMS(proto), PARAMS(args), PARAMS(tstruct), \ + PARAMS(assign), PARAMS(print)) \ +static notrace void \ +trace_event_raw_event_##call(void *__data, proto) \ +{ \ + preempt_disable_notrace(); \ + do_trace_event_raw_event_##call(__data, args); \ + preempt_enable_notrace(); \ +} + /* * The ftrace_test_probe is compiled out, it is only here as a build time = check * to make sure that if the tracepoint handling changes, the ftrace probe = will * fail to compile unless it too is updated. */ =20 -#undef DECLARE_EVENT_SYSCALL_CLASS -#define DECLARE_EVENT_SYSCALL_CLASS DECLARE_EVENT_CLASS - #undef DEFINE_EVENT #define DEFINE_EVENT(template, call, proto, args) \ static inline void ftrace_test_probe_##call(void) \ @@ -443,6 +466,8 @@ static inline void ftrace_test_probe_##call(void) \ =20 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE) =20 +#undef __DECLARE_EVENT_CLASS + #include "stages/stage7_class_define.h" =20 #undef DECLARE_EVENT_CLASS diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index 785733245ead..f9b21bac9d45 100644 --- a/kernel/trace/trace_syscalls.c +++ b/kernel/trace/trace_syscalls.c @@ -299,6 +299,12 @@ static void ftrace_syscall_enter(void *data, struct pt= _regs *regs, long id) int syscall_nr; int size; =20 + /* + * Syscall probe called with preemption enabled, but the ring + * buffer and per-cpu data require preemption to be disabled. + */ + guard(preempt_notrace)(); + syscall_nr =3D trace_get_syscall_nr(current, regs); if (syscall_nr < 0 || syscall_nr >=3D NR_syscalls) return; @@ -338,6 +344,12 @@ static void ftrace_syscall_exit(void *data, struct pt_= regs *regs, long ret) struct trace_event_buffer fbuffer; int syscall_nr; =20 + /* + * Syscall probe called with preemption enabled, but the ring + * buffer and per-cpu data require preemption to be disabled. + */ + guard(preempt_notrace)(); + syscall_nr =3D trace_get_syscall_nr(current, regs); if (syscall_nr < 0 || syscall_nr >=3D NR_syscalls) return; --=20 2.39.2