next-20250909: selftests/arm64/gcs/basic-gcs.c:390:30: error: use of undeclared identifier 'HWCAP_GCS'

[Naresh Kamboju]

Hi Thomas,

On Fri, 12 Sept 2025 at 12:00, Thomas Weißschuh <linux at weissschuh.net> wrote:
>
> Hi Naresh,
>
> On 2025-09-12 00:48:47+0530, Naresh Kamboju wrote:
> > The following build warnings / errors noticed on arm64 defconfig
> > with clang-20 and gcc-13 toolchains on the Linux next-20250909
> > till next-20250911 tag while building selftests/arm64.
> >
> > Regression Analysis:
> > - New regression? Yes
> > - Reproducibility? yes
> >
> > First seen on  next-20250909
> >  Good: next-20250908
> >  Bad: next-20250909 till next-20250911
> >
> > Test regression: next-20250909:
> > selftests/arm64/gcs/basic-gcs.c:390:30: error: use of undeclared
> > identifier 'HWCAP_GCS'
> >
> > Reported-by: Linux Kernel Functional Testing <lkft at linaro.org>
> >
> > ## Build log
> > selftests/arm64/gcs/basic-gcs.c:390:30: error: use of undeclared
> > identifier 'HWCAP_GCS'
> >   390 |         if (!(getauxval(AT_HWCAP) & HWCAP_GCS))
> >       |                                     ^
> > 1 error generated.
> >
> > The suspected commit pointing to,
> >   kselftest/arm64/gcs: Use nolibc's getauxval()
> >   a985fe638344492727528e52416211dda1c391d5
>
> That suspicion looks correct. I am wondering a bit how this works for
> the other selftests which use this symbol.
>
> Can you give this one a try:
>

I have applied this patch and tested and reported build regressions
got fixed.

Tested-by: Linux Kernel Functional Testing <lkft at linaro.org>

> diff --git a/tools/testing/selftests/arm64/gcs/gcs-util.h b/tools/testing/selftests/arm64/gcs/gcs-util.h
> index c99a6b39ac14..816b497634d6 100644
> --- a/tools/testing/selftests/arm64/gcs/gcs-util.h
> +++ b/tools/testing/selftests/arm64/gcs/gcs-util.h
> @@ -26,6 +26,10 @@ struct user_gcs {
>  };
>  #endif
>
> +#ifndef HWCAP_GCS
> +#define HWCAP_GCS (1UL << 32)
> +#endif
> +
>  /* Shadow Stack/Guarded Control Stack interface */
>  #define PR_GET_SHADOW_STACK_STATUS     74
>  #define PR_SET_SHADOW_STACK_STATUS      75

--
Linaro LKFT