On 2024-10-04 00:37, Steven Rostedt wrote:
On Thu, 3 Oct 2024 11:16:37 -0400
Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> wrote:
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.
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/perf.h | 1 +
kernel/trace/trace_syscalls.c | 2 ++
2 files changed, 3 insertions(+)
diff --git a/include/trace/perf.h b/include/trace/perf.h
index 5650c1bad088..321bfd7919f6 100644
--- a/include/trace/perf.h
+++ b/include/trace/perf.h
@@ -84,6 +84,7 @@ perf_trace_##call(void *__data, proto) \
u64 __count __attribute__((unused)); \
struct task_struct *__task __attribute__((unused)); \
\
+ might_fault(); \
guard(preempt_notrace)(); \
do_perf_trace_##call(__data, args); \
Same for this. This is used for all tracepoints that perf hooks to.
You're also missing the context:
#undef DECLARE_EVENT_SYSCALL_CLASS
#define DECLARE_EVENT_SYSCALL_CLASS(call, proto, args, tstruct, assign, print) \
__DECLARE_EVENT_CLASS(call, PARAMS(proto), PARAMS(args), PARAMS(tstruct), \
PARAMS(assign), PARAMS(print)) \
static notrace void \
perf_trace_##call(void *__data, proto) \
{ \
u64 __count __attribute__((unused)); \
struct task_struct *__task __attribute__((unused)); \
\
might_fault(); \
guard(preempt_notrace)(); \
do_perf_trace_##call(__data, args); \
}
Not an issue.
Thanks,
Mathieu
-- Steve
}
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 89d7e4c57b5b..0d42d6f293d6 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -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);
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
