linux-kernel - [PATCH v4 8/8] tracing/bpf: Add might

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Message-Id: <20241009010718.2050182-9-mathieu.desnoyers@efficios.com>
Date: Tue,  8 Oct 2024 21:07:18 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>
Cc: linux-kernel@...r.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Yonghong Song <yhs@...com>,
	"Paul E . McKenney" <paulmck@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Andrii Nakryiko <andrii.nakryiko@...il.com>,
	bpf@...r.kernel.org,
	Joel Fernandes <joel@...lfernandes.org>,
	linux-trace-kernel@...r.kernel.org,
	Andrii Nakryiko <andrii@...nel.org>,
	Michael Jeanson <mjeanson@...icios.com>
Subject: [PATCH v4 8/8] tracing/bpf: Add might_fault check to syscall probes

Add a might_fault() check to validate that the bpf sys_enter/sys_exit
probe callbacks are indeed called from a context where page faults can
be handled.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Acked-by: Andrii Nakryiko <andrii@...nel.org>
Tested-by: Andrii Nakryiko <andrii@...nel.org> # BPF parts
Cc: Michael Jeanson <mjeanson@...icios.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Yonghong Song <yhs@...com>
Cc: Paul E. McKenney <paulmck@...nel.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: bpf@...r.kernel.org
Cc: Joel Fernandes <joel@...lfernandes.org>
---
 include/trace/bpf_probe.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/trace/bpf_probe.h b/include/trace/bpf_probe.h
index fec97c93e1c9..183fa2aa2935 100644
--- a/include/trace/bpf_probe.h
+++ b/include/trace/bpf_probe.h
@@ -57,6 +57,7 @@ __bpf_trace_##call(void *__data, proto)					\
 static notrace void							\
 __bpf_trace_##call(void *__data, proto)					\
 {									\
+	might_fault();							\
 	preempt_disable_notrace();					\
 	CONCATENATE(bpf_trace_run, COUNT_ARGS(args))(__data, CAST_TO_U64(args));	\
 	preempt_enable_notrace();					\
-- 
2.39.2