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

Josh Poimboeuf
2025-02-14T19:34:03Z

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.

BTW, I realized the wrong function size shown in the WARNING stack trace
is probably just due to a kallsyms quirk. It calculates a symbol's size
by subtracting its start address from the next symbol's start address.
It doesn't actually use the ELF symbol size. So the next symbol after
copy_process() in the loaded module's address space might just be far
away.

That kallsyms issue has caused other headaches. It really needs to be
fixed to use the actual ELF symbol size.

--
Josh