Re: [PATCH 0/8] unwind, arm64: add sframe unwinder for kernel

Josh Poimboeuf
2025-02-14T22:33:28Z

On Fri, Feb 14, 2025 at 02:04:17PM -0800, Song Liu wrote:
> Hi Josh,
>
> On Fri, Feb 14, 2025 at 11:34 AM Josh Poimboeuf <jpoimboe@kernel.org> wrote:
> >
> > On Fri, Feb 14, 2025 at 09:51:41AM -0800, Song Liu wrote:
> > > > Ignorant arm64 question: is the module's text further away from slab
> > > > memory than vmlinux text, thus requiring a different instruction (or
> > > > GOT/TOC) to access memory further away in the address space?
> > >
> > > It appears to me the module text is very close to vmlinux text:
> > >
> > > vmlinux: ffff8000800b4b68 T copy_process
> > > module: ffff80007b0f06d0 t copy_process [livepatch_always_inline_special_static]
> >
> > Hm... the only other thing I can think of is that the klp relas might be
> > wrong somewhere. If you share patched.o and .ko files from the same
> > build I could take a look.
>
> A tarball with these files is available here:
>
> https://drive.google.com/file/d/1ONB1tC9oK-Z5ShmSXneqWLTjJgC5Xq-C/view?usp=drive_link

Thanks, I'll take a look.

> > That kallsyms issue has caused other headaches. It really needs to be
> > fixed to use the actual ELF symbol size.
>
> Maybe we should have a "module_text_end" symbol?

Maybe, though it would be a lot cleaner for kallsyms to just use the
actual ELF sizes. And actually I'm thinking that would be a pretty
trivial change.

--
Josh