[PATCH 0/2] kselftest/arm64/gcs: Cleanups for basic-gcs.c

[PATCH 0/2] kselftest/arm64/gcs: Cleanups for basic-gcs.c

[Thomas Weißschuh]

Two small cleanups.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
Thomas Weißschuh (2):
      kselftest/arm64/gcs: Correctly check return value when disabling GCS
      kselftest/arm64/gcs: Use nolibc's getauxval()

 tools/testing/selftests/arm64/gcs/basic-gcs.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)
---
base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
change-id: 20250821-nolibc-gcs-fixes-11cf7585bb74

Best regards,
-- 
Thomas Weißschuh <linux@weissschuh.net>

[PATCH 1/2] kselftest/arm64/gcs: Correctly check return value when disabling GCS

[Thomas Weißschuh]

The return value was not assigned to 'ret', so the check afterwards
does not do anything.

Fixes: 3d37d4307e0f ("kselftest/arm64: Add very basic GCS test program")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 tools/testing/selftests/arm64/gcs/basic-gcs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/arm64/gcs/basic-gcs.c b/tools/testing/selftests/arm64/gcs/basic-gcs.c
index 54f9c888249d74451e1432280a395156ce72e56c..100d2a983155f7347a19b2b8b88f9494dc6a51d5 100644
--- a/tools/testing/selftests/arm64/gcs/basic-gcs.c
+++ b/tools/testing/selftests/arm64/gcs/basic-gcs.c
@@ -410,7 +410,7 @@ int main(void)
 	}
 
 	/* One last test: disable GCS, we can do this one time */
-	my_syscall5(__NR_prctl, PR_SET_SHADOW_STACK_STATUS, 0, 0, 0, 0);
+	ret = my_syscall5(__NR_prctl, PR_SET_SHADOW_STACK_STATUS, 0, 0, 0, 0);
 	if (ret != 0)
 		ksft_print_msg("Failed to disable GCS: %d\n", ret);
 

-- 
2.50.1

Re: [PATCH 1/2] kselftest/arm64/gcs: Correctly check return value when disabling GCS

[Mark Brown]

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On Thu, Aug 21, 2025 at 05:13:02PM +0200, Thomas Weißschuh wrote:
> The return value was not assigned to 'ret', so the check afterwards
> does not do anything.

Reviewed-by: Mark Brown <broonie@kernel.org>

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[PATCH 2/2] kselftest/arm64/gcs: Use nolibc's getauxval()

[Thomas Weißschuh]

Nolibc now does have getauxval(), use it.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 tools/testing/selftests/arm64/gcs/basic-gcs.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/arm64/gcs/basic-gcs.c b/tools/testing/selftests/arm64/gcs/basic-gcs.c
index 100d2a983155f7347a19b2b8b88f9494dc6a51d5..250977abc3988685abf68666d35b7a8547f74f4e 100644
--- a/tools/testing/selftests/arm64/gcs/basic-gcs.c
+++ b/tools/testing/selftests/arm64/gcs/basic-gcs.c
@@ -10,6 +10,7 @@
 
 #include <sys/mman.h>
 #include <asm/mman.h>
+#include <asm/hwcap.h>
 #include <linux/sched.h>
 
 #include "kselftest.h"
@@ -386,14 +387,13 @@ int main(void)
 
 	ksft_print_header();
 
-	/*
-	 * We don't have getauxval() with nolibc so treat a failure to
-	 * read GCS state as a lack of support and skip.
-	 */
+	if (!(getauxval(AT_HWCAP) & HWCAP_GCS))
+		ksft_exit_skip("SKIP GCS not supported\n");
+
 	ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS,
 			  &gcs_mode, 0, 0, 0);
 	if (ret != 0)
-		ksft_exit_skip("Failed to read GCS state: %d\n", ret);
+		ksft_exit_fail_msg("Failed to read GCS state: %d\n", ret);
 
 	if (!(gcs_mode & PR_SHADOW_STACK_ENABLE)) {
 		gcs_mode = PR_SHADOW_STACK_ENABLE;

-- 
2.50.1

Re: [PATCH 2/2] kselftest/arm64/gcs: Use nolibc's getauxval()

[Mark Brown]

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On Thu, Aug 21, 2025 at 05:13:03PM +0200, Thomas Weißschuh wrote:
> Nolibc now does have getauxval(), use it.

Reviewed-by: Mark Brown <broonie@kernel.org>

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Re: [PATCH 0/2] kselftest/arm64/gcs: Cleanups for basic-gcs.c

[Will Deacon]

On Thu, 21 Aug 2025 17:13:01 +0200, Thomas Weißschuh wrote:
> Two small cleanups.
> 
> 

Applied to arm64 (for-next/selftests), thanks!

[1/2] kselftest/arm64/gcs: Correctly check return value when disabling GCS
      https://git.kernel.org/arm64/c/740cdafd0d99
[2/2] kselftest/arm64/gcs: Use nolibc's getauxval()
      https://git.kernel.org/arm64/c/a985fe638344

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev