Re: [PATCH 8/8] tracing/bpf: Add might_fault check to syscall probes

[Andrii Nakryiko]

On Mon, Sep 9, 2024 at 1:17 PM Mathieu Desnoyers
<mathieu.desnoyers@xxxxxxxxxxxx> 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@xxxxxxxxxxxx>
> Cc: Michael Jeanson <mjeanson@xxxxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> Cc: Yonghong Song <yhs@xxxxxx>
> Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx>
> Cc: bpf@xxxxxxxxxxxxxxx
> Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
> ---
>  include/trace/bpf_probe.h | 1 +
>  1 file changed, 1 insertion(+)
>

LGTM.

Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>

> 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
>