Re: [PATCH v2] kselftest/arm64: Fix build failure with GCC-15

[Leo Yan <leo.yan@arm.com>]

On Fri, Apr 24, 2026 at 06:09:01PM +0100, Mark Brown wrote:
> On Fri, Apr 24, 2026 at 05:44:16PM +0100, Catalin Marinas wrote:
> 
> > OK, so it does look like it picks the kernel uapi/asm/ptrace.h. It
> > builds fine on Debian stable (no GCS anywhere) with including
> > asm/ptrace.h and removing struct user_gcs.

kselftest has the GCC option: "-isystem $(top_srcdir)/usr/include",
So asm/ptrace.h does come from kernel's usr/include/asm/ptrace.h.

NT_ARM_GCS comes from /usr/aarch64-linux-gnu/include/elf.h.

> > But I think we should include asm/ptrace.h in libc-gcs.h and not the
> > gcs-util.h header (for NT_ARM_GCS it's fine to keep in gcs-util.h).
> 
> It's not glibc specific so it seems reasonable to keep it in gcs-util.h,
> even though we don't currently have any nolibc stuff that uses ptrace.
> That said this isn't particularly strongly held opinion so I don't
> *really* mind either way.

Does below change make sense to you?

Subject: [PATCH] kselftest/arm64: Include <asm/ptrace.h> for user_gcs definition

kselftest includes kernel uAPI headers with option:

  -isystem $(top_srcdir)/usr/include

Include <asm/ptrace.h> in libc-gcs.c for the definition of struct
user_gcs from the uAPI headers, and remove the redundant
definition in gcs-util.h.

Fixes: a505a52b4e29 ("kselftest/arm64: Add a GCS test program built with the system libc")
Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 tools/testing/selftests/arm64/gcs/gcs-util.h | 6 ------
 tools/testing/selftests/arm64/gcs/libc-gcs.c | 1 +
 2 files changed, 1 insertion(+), 6 deletions(-)

diff --git a/tools/testing/selftests/arm64/gcs/gcs-util.h b/tools/testing/selftests/arm64/gcs/gcs-util.h
index c99a6b39ac14..7a81bb07ed4b 100644
--- a/tools/testing/selftests/arm64/gcs/gcs-util.h
+++ b/tools/testing/selftests/arm64/gcs/gcs-util.h
@@ -18,12 +18,6 @@
 
 #ifndef NT_ARM_GCS
 #define NT_ARM_GCS 0x410
-
-struct user_gcs {
-	__u64 features_enabled;
-	__u64 features_locked;
-	__u64 gcspr_el0;
-};
 #endif
 
 /* Shadow Stack/Guarded Control Stack interface */
diff --git a/tools/testing/selftests/arm64/gcs/libc-gcs.c b/tools/testing/selftests/arm64/gcs/libc-gcs.c
index 17b2fabfec38..72e82bfbecc9 100644
--- a/tools/testing/selftests/arm64/gcs/libc-gcs.c
+++ b/tools/testing/selftests/arm64/gcs/libc-gcs.c
@@ -16,6 +16,7 @@
 
 #include <asm/hwcap.h>
 #include <asm/mman.h>
+#include <asm/ptrace.h>
 
 #include <linux/compiler.h>
 
-- 
2.34.1