Re: [PATCH] [PATCH v2] AARCH64: Add gcc Shadow Call Stack support

[Dan Li]

On 2/25/22 12:47, Miguel Ojeda wrote:
> On Fri, Feb 25, 2022 at 4:24 AM Dan Li <ashimida@xxxxxxxxxxxxxxxxx> wrote:
> > +         - Clang (https://clang.llvm.org/docs/ShadowCallStack.html)
> > +         - GCC (https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options)
>
> Maybe Clang: and GCC: instead of the parenthesis?
Got it.

> > +#ifdef CONFIG_SHADOW_CALL_STACK
> > +#define __noscs __attribute__((__no_sanitize__("shadow-call-stack")))
> > +#endif
>
> Since both compilers have it, and I guess the `#ifdef` condition would
> work for both, could this be moved into `compiler_types.h` where the
> empty `__noscs` definition is, and remove the one from
> `compiler-clang.h`?
In the clang documentation I see __has_feature(shadow_call_stack) is
used to check if -fsanitize=shadow-call-stack is enabled, so I think
maybe it's fine to use "#ifdef CONFIG_SHADOW_CALL_STACK"
instead of "#if __has_attribute(__no_sanitize_address__)" here, then
move it to `compiler_types.h`.

And from the results of my local clang 12 compilation, this doesn't
seem to be a problem.

Link: https://clang.llvm.org/docs/ShadowCallStack.html#has-feature-shadow-call-stack