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Message-ID: <e18e953b-9030-487c-bb8a-125521568e9e@efficios.com>
Date: Mon, 28 Oct 2024 15:58:06 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
Michael Jeanson <mjeanson@...icios.com>,
Masami Hiramatsu <mhiramat@...nel.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>,
Andrii Nakryiko <andrii.nakryiko@...il.com>, bpf@...r.kernel.org,
Joel Fernandes <joel@...lfernandes.org>, Jordan Rife <jrife@...gle.com>
Subject: Re: [RFC PATCH v4 4/4] tracing: Add might_fault() check in
__DO_TRACE() for syscall
On 2024-10-28 15:09, Mathieu Desnoyers wrote:
> Catch incorrect use of syscall tracepoints even if no probes are
> registered by adding a might_fault() check in __DO_TRACE() when
> syscall=1.
>
> Suggested-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> 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>
> Cc: Jordan Rife <jrife@...gle.com>
> ---
> include/linux/tracepoint.h | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
> index 259f0ab4ece6..7bed499b7055 100644
> --- a/include/linux/tracepoint.h
> +++ b/include/linux/tracepoint.h
> @@ -226,10 +226,12 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
> if (!(cond)) \
> return; \
> \
> - if (syscall) \
> + if (syscall) { \
> rcu_read_lock_trace(); \
> - else \
> + might_fault(); \
Actually, __DO_TRACE() is not the best place to put this, because it's
only executed when the tracepoint is enabled.
I'll move this to __DECLARE_TRACE_SYSCALL()
#define __DECLARE_TRACE_SYSCALL(name, proto, args, cond, data_proto) \
__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), cond, PARAMS(data_proto)) \
static inline void trace_##name(proto) \
{ \
might_fault(); \
if (static_branch_unlikely(&__tracepoint_##name.key)) \
__DO_TRACE(name, \
TP_ARGS(args), \
TP_CONDITION(cond), 1); \
[...]
instead in v5.
Thanks,
Mathieu
> + } else { \
> preempt_disable_notrace(); \
> + } \
> \
> __DO_TRACE_CALL(name, TP_ARGS(args)); \
> \
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
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