Re: [PATCH v4 1/2] powerpc/uaccess: Implement unsafe_put_user() using 'asm goto'

Michael Ellerman
2020-06-13T10:46:50Z

Nick Desaulniers <ndesaulniers@google.com> writes:

> On Thu, Jun 11, 2020 at 4:53 PM Segher Boessenkool
> <segher@kernel.crashing.org> wrote:
>>
>> On Thu, Jun 11, 2020 at 03:43:55PM -0700, Nick Desaulniers wrote:
>> > Segher, Cristophe, I suspect Clang is missing support for the %L and %U
>> > output templates [1].
...
>
> IIUC the bug report correctly, it looks like LLVM is failing for the
> __put_user_asm2_goto case for -m32. A simple reproducer:
> https://godbolt.org/z/jBBF9b

If you add `-mregnames` you get register names:

https://godbolt.org/z/MxLjhF

foo:
stw %r3, 0(%r5)
stw %r4, 4(%r5)
blr

cheers