Commit cdb537ac authored Oct 08, 2024 by Mathieu Desnoyers Committed by Steven Rostedt (Google) Oct 09, 2024

tracing/perf: Add might_fault check to syscall probes

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

Cc: Michael Jeanson <mjeanson@efficios.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Yonghong Song <yhs@fb.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf@vger.kernel.org
Cc: Joel Fernandes <joel@joelfernandes.org>
Link: https://lore.kernel.org/20241009010718.2050182-8-mathieu.desnoyers@efficios.com

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

parent a3204c74

include/trace/perf.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -84,6 +84,7 @@ perf_trace_##call(void *__data, proto) \
		u64 __count __attribute__((unused)); \
		struct task_struct *__task __attribute__((unused)); \
		\
		might_fault(); \
		preempt_disable_notrace(); \
		do_perf_trace_##call(__data, args); \
		preempt_enable_notrace(); \

kernel/trace/trace_syscalls.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -602,6 +602,7 @@ static void perf_syscall_enter(void ignore, struct pt_regs regs, long id)
		* Syscall probe called with preemption enabled, but the ring
		* buffer and per-cpu data require preemption to be disabled.
		*/
		might_fault();
		guard(preempt_notrace)();

		syscall_nr = trace_get_syscall_nr(current, regs);
		@@ -710,6 +711,7 @@ static void perf_syscall_exit(void ignore, struct pt_regs regs, long ret)
		* Syscall probe called with preemption enabled, but the ring
		* buffer and per-cpu data require preemption to be disabled.
		*/
		might_fault();
		guard(preempt_notrace)();

		syscall_nr = trace_get_syscall_nr(current, regs);