[PATCH v3 1/2] arm64: Implement arch_stack_walk_reliable

Weinan Liu
2025-03-20T17:46:44Z

On Thu, Mar 20, 2025 at 10:16 AM Song Liu <song@kernel.org> wrote:
>
> static __always_inline void
> @@ -230,8 +231,26 @@ kunwind_next_frame_record(struct kunwind_state *state)
> new_fp = READ_ONCE(record->fp);
> new_pc = READ_ONCE(record->lr);
>
> - if (!new_fp && !new_pc)
> - return kunwind_next_frame_record_meta(state);
> + if (!new_fp && !new_pc) {
> + int ret;
> +
> + ret = kunwind_next_frame_record_meta(state);

The exception case kunwind_next_regs_pc() will return 0 when unwind success.
Should we return a different value for the success case of kunwind_next_regs_pc()?

> + if (ret < 0) {
> + /*
> + * This covers two different conditions:
> + * 1. ret == -ENOENT, unwinding is done.
> + * 2. ret == -EINVAL, unwinding hit error.
> + */
> + return ret;
> + }
> + /*
> + * Searching across exception boundaries. The stack is now
> + * unreliable.
> + */
> + if (state->end_on_unreliable)
> + return -EINVAL;
> + return 0;
> + }