Re: [PATCH 06/18] add support for Clang's Shadow Call Stack (SCS)

Miguel Ojeda
2019-10-18T18:33:18Z

On Fri, Oct 18, 2019 at 7:11 PM Sami Tolvanen <samitolvanen@google.com> wrote:
>
> On Fri, Oct 18, 2019 at 10:08 AM 'Nick Desaulniers' via Clang Built
> Linux <clang-built-linux@googlegroups.com> wrote:
> > > diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
> > > index 333a6695a918..9af08391f205 100644
> > > --- a/include/linux/compiler-clang.h
> > > +++ b/include/linux/compiler-clang.h
> > > @@ -42,3 +42,5 @@
> > > * compilers, like ICC.
> > > */
> > > #define barrier() __asm__ __volatile__("" : : : "memory")
> > > +
> > > +#define __noscs __attribute__((no_sanitize("shadow-call-stack")))
> >
> > It looks like this attribute, (and thus a requirement to use this
> > feature), didn't exist until Clang 7.0: https://godbolt.org/z/p9u1we
> > (as noted above)
> >
> > I think it's better to put __noscs behind a __has_attribute guard in
> > include/linux/compiler_attributes.h. Otherwise, what will happen when
> > Clang 6.0 sees __noscs, for example? (-Wunknown-sanitizers will
> > happen).
>
> Good point, I'll fix this in v2. Thanks.

+1, please CC whenever you send it!

Cheers,
Miguel