Re: [PATCH 2/2] x86/unwind/orc: Support reliable unwinding through BPF stack frames

[Song Liu]

On Tue, Dec 2, 2025 at 10:20 AM Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
>
> BPF JIT programs and trampolines use a frame pointer, so the current ORC
> unwinder strategy of falling back to frame pointers (when an ORC entry
> is missing) usually works in practice when unwinding through BPF JIT
> stack frames.
>
> However, that frame pointer fallback is just a guess, so the unwind gets
> marked unreliable for live patching, which can cause livepatch
> transition stalls.
>
> Make the common case reliable by calling the bpf_has_frame_pointer()
> helper to detect the valid frame pointer region of BPF JIT programs and
> trampolines.
>
> Fixes: ee9f8fce9964 ("x86/unwind: Add the ORC unwinder")
> Reported-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxxxxxxxxxx>
> Closes: https://lore.kernel.org/0e555733-c670-4e84-b2e6-abb8b84ade38@xxxxxxxxxxxxxxx
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

Acked-by: Song Liu <song@xxxxxxxxxx>