[PATCH v4 07/12] ppc64/kexec_file: add support to relocate purgatory

[Michael Ellerman]

Hari Bathini <hbathini at linux.ibm.com> writes:
> Right now purgatory implementation is only minimal. But if purgatory
> code is to be enhanced to copy memory to the backup region and verify
> sha256 digest, relocations may have to be applied to the purgatory.
> So, add support to relocate purgatory in kexec_file_load system call
> by setting up TOC pointer and applying RELA relocations as needed.
>
> Reported-by: kernel test robot <lkp at intel.com>
> [lkp: In v1, 'struct mem_sym' was declared in parameter list]
> Signed-off-by: Hari Bathini <hbathini at linux.ibm.com>
> ---
>
> * Michael, can you share your opinion on the below:
>     - https://lore.kernel.org/patchwork/patch/1272027/
>     - My intention in cover note.

It seems like a lot of complexity for little benefit.

AFAICS your final purgatory_64.c is only 36 lines, and all it does is a
single (open coded) memcpy().

It seems like we could write that in not many more lines of assembler
and avoid all this code.

What am I missing?

cheers