[PATCH v4 8/8] tracing/bpf: Add might_fault check to syscall probes

[Mathieu Desnoyers]

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>
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Tested-by: Andrii Nakryiko <andrii@xxxxxxxxxx> # BPF parts
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(+)

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