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

[Naresh Kamboju]

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


## Source
* Kernel version: 6.17.0-rc5
* Git tree: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git
* Git describe: 6.17.0-rc5-next-20250911
* Git commit: 8f21d9da46702c4d6951ba60ca8a05f42870fe8f
* Architectures: arm64
* Toolchains: gcc-13 and clang-20
* Kconfigs: defconfig

## Build
* Build log: https://qa-reports.linaro.org/api/testruns/29827060/log_file/
* Build details:
https://regressions.linaro.org/lkft/linux-next-master/next-20250909/log-parser-build-clang/clang-compiler-basic-gcs_c-error-use-of-undeclared-identifier-hwcap_gcs/
* Build plan: https://tuxapi.tuxsuite.com/v1/groups/linaro/projects/lkft/builds/32RzudgbCUiqGUoFtquJ9IEIDXZ
* Build link: https://storage.tuxsuite.com/public/linaro/lkft/builds/32RzudgbCUiqGUoFtquJ9IEIDXZ/
* Kernel config:
https://storage.tuxsuite.com/public/linaro/lkft/builds/32RzudgbCUiqGUoFtquJ9IEIDXZ/config

## Steps to reproduce
 $ tuxmake --runtime podman --target-arch arm64 \
 --toolchain clang-nightly \
 --kconfig https://storage.tuxsuite.com/public/linaro/lkft/builds/32RzudgbCUiqGUoFtquJ9IEIDXZ/config
\
 LLVM=1 LLVM_IAS=1 debugkernel dtbs dtbs-legacy headers kernel kselftest modules

--
Linaro LKFT