On Wed, Oct 14, 2020 at 3:51 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> I think it's this instruction:
>
>         addi    r1,r1,16
>
> that should be removed from the function exit, because Al removed the
>
> -       stwu    r1,-16(r1)
>
> on function entry.
>
> So I think you end up with a corrupt stack pointer and basically
> random behavior.
>
> Mind trying that? (This is obviously all in
> arch/powerpc/lib/checksum_32.S, the csum_partial_copy_generic()
> function).

Patch attached to make it easier to test.

NOTE! This is ENTIRELY untested. My ppc asm is so rusty that I might
be barking entirely up the wrong tree, and I just made things much
worse.

                 Linus