RE: [RFC PATCH v8 3/4] arm64: Introduce stack trace reliability checks in the unwinder
From: nobuta.keiya@fujitsu.com <hidden>
Date: 2021-08-24 06:02:38
Also in:
linux-arm-kernel, lkml
Hi Madhavan,
quoted hunk ↗ jump to hunk
@@ -245,7 +271,36 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, fp = thread_saved_fp(task); pc = thread_saved_pc(task); } - unwind(consume_entry, cookie, task, fp, pc); + unwind(consume_entry, cookie, task, fp, pc, false); +} + +/* + * arch_stack_walk_reliable() may not be used for livepatch until all of + * the reliability checks are in place in unwind_consume(). However, + * debug and test code can choose to use it even if all the checks are not + * in place. + */
I'm glad to see the long-awaited function :) Does the above comment mean that this comment will be removed by another patch series that about live patch enablement, instead of [PATCH 4/4]? It seems to take time... But I start thinking about test code. Thanks, Keiya
+noinline int notrace arch_stack_walk_reliable(stack_trace_consume_fn consume_fn,
+ void *cookie,
+ struct task_struct *task)
+{
+ unsigned long fp, pc;
+
+ if (!task)
+ task = current;
+
+ if (task == current) {
+ /* Skip arch_stack_walk_reliable() in the stack trace. */
+ fp = (unsigned long)__builtin_frame_address(1);
+ pc = (unsigned long)__builtin_return_address(0);
+ } else {
+ /* Caller guarantees that the task is not running. */
+ fp = thread_saved_fp(task);
+ pc = thread_saved_pc(task);
+ }
+ if (unwind(consume_fn, cookie, task, fp, pc, true))
+ return 0;
+ return -EINVAL;
}
#endif
--
2.25.1