Re: "arm64: vdso: Substitute gettimeofday() with C implementation" breaks clang build

[Will Deacon]

On Tue, Jun 25, 2019 at 06:00:27PM +0100, Vincenzo Frascino wrote:
> On 25/06/2019 17:26, Nick Desaulniers wrote:
> > On Tue, Jun 25, 2019 at 7:54 AM Vincenzo Frascino
> > <vincenzo.frascino@xxxxxxx> wrote:
> >>> but clang 7.0 is still use in many distros by default, so maybe this commit can
> >>> be fixed by adding a conditional check to use "small" if clang version < 8.0.
> >>>
> >>
> >> Could you please verify that the patch below works for you?
> > 
> > Should it be checking against CONFIG_CLANG_VERSION, or better yet be
> > using cc-option macro?
> > 
> 
> This is what I did in my proposed patch, but I was surprised that clang-7
> generates relocations that clang-8 does not.
> 
>   LD      arch/arm64/kernel/vdso/vdso.so.dbg
>   VDSOCHK arch/arm64/kernel/vdso/vdso.so.dbg
> 00000000000009d0 R_AARCH64_JUMP_SLOT  _mcount

Hmm. It would be nice to understand where the reference to _mcount is coming
from, since that sounds like ftrace is getting involved where it shouldn't
be.

Will