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

From: Josh Poimboeuf
Date: Fri Feb 14 2025 - 18:23:52 EST


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@xxxxxxxxxx> 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

Poking around the arm64 module code, arch/arm64/kernel/module-plts.c
is looking at all the relocations in order to set up the PLT. That also
needs to be done for klp relas, or are your patches already doing that?

--
Josh