linux-kernel - [PATCH v3 1/2] arm64: Implement arch_stack_walk

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Message-ID: <20250320174642.855602-1-wnliu@google.com>
Date: Thu, 20 Mar 2025 17:46:41 +0000
From: Weinan Liu <wnliu@...gle.com>
To: song@...nel.org
Cc: indu.bhagat@...cle.com, irogers@...gle.com, joe.lawrence@...hat.com, 
	jpoimboe@...nel.org, kernel-team@...a.com, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-toolchains@...r.kernel.org, live-patching@...r.kernel.org, 
	mark.rutland@....com, peterz@...radead.org, puranjay@...nel.org, 
	roman.gushchin@...ux.dev, rostedt@...dmis.org, will@...nel.org, 
	wnliu@...gle.com
Subject: [PATCH v3 1/2] arm64: Implement arch_stack_walk_reliable

On Thu, Mar 20, 2025 at 10:16 AM Song Liu <song@...nel.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;
> +       }