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

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Message-ID: <CAEf4Bza07qWL1o9Y-ZZddrsH-hm6nse7855bjpCurAZvf5C_2w@mail.gmail.com>
Date: Mon, 9 Sep 2024 17:02:58 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, 
	linux-kernel@...r.kernel.org, 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>, 
	bpf@...r.kernel.org, Joel Fernandes <joel@...lfernandes.org>, 
	linux-trace-kernel@...r.kernel.org, Michael Jeanson <mjeanson@...icios.com>
Subject: Re: [PATCH 8/8] tracing/bpf: Add might_fault check to syscall probes

On Mon, Sep 9, 2024 at 1:17 PM Mathieu Desnoyers
<mathieu.desnoyers@...icios.com> wrote:
>
> 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>
> 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(+)
>

LGTM.

Acked-by: Andrii Nakryiko <andrii@...nel.org>

> diff --git a/include/trace/bpf_probe.h b/include/trace/bpf_probe.h
> index 211b98d45fc6..099df5c3e38a 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();                                                  \
>         guard(preempt_notrace)();                                       \
>         CONCATENATE(bpf_trace_run, COUNT_ARGS(args))(__data, CAST_TO_U64(args));        \
>  }
> --
> 2.39.2
>