Re: [PATCH v2 0/6] unwind, arm64: add sframe unwinder for kernel

On Fri, Nov 14, 2025 at 10:50:16PM -0800, Dylan Hatch wrote:
> On Mon, Sep 29, 2025 at 12:55 PM Puranjay Mohan <[email protected]> wrote:
> >
> > I will try to debug this more but am just curious about BPF's
> > interactions with sframe.
> > The sframe data for bpf programs doesn't exist, so we would need to
> > add that support
> > and that wouldn't be trivial, given the BPF programs are JITed.
> >
> > Thanks,
> > Puranjay
> 
> From what I can tell, the ORC unwinder in x86 falls back to using
> frame pointers in cases of generated code, like BPF. Would matching
> this behavior in the sframe unwinder be a reasonable approach, at
> least for the purposes of enabling reliable unwind for livepatch?

The ORC unwinder marks the unwind "unreliable" if it has to fall back to
frame pointers.

But that's not a problem for livepatch because it only[*] unwinds
blocked/sleeping tasks, which shouldn't have BPF on their stack anyway.

[*] with one exception: the task calling into livepatch

-- 
Josh