Building on Debian sid with GCC 15 fails:

    CC       libc-gcs
  libc-gcs.c: In function 'ptrace_read_write':
  libc-gcs.c:142:25: error: storage size of 'child_gcs' isn't known
    142 |         struct user_gcs child_gcs;
        |                         ^~~~~~~~~
  libc-gcs.c:142:25: warning: unused variable 'child_gcs' [-Wunused-variable]

GCC-15 defines NT_ARM_GCS in the toolchain headers, causing gcs-util.h
to skip its fallback definition of struct user_gcs. This leads to the
compiler error.

Fix this by including <asm/ptrace.h> to provide the proper definition.

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/libc-gcs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/arm64/gcs/libc-gcs.c b/tools/testing/selftests/arm64/gcs/libc-gcs.c
index 17b2fabfec386e523e788d8bcfcafa553c93bd9b..72e82bfbecc99e34da71d56cf5401c137d6e9a48 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>
 

---
base-commit: 4ee64205ffaa587e8114d84a67ac721399ccb369
change-id: 20260421-selftests_arm64_gcc15-15f6f6d07dd8

Best regards,
-- 
Leo Yan <leo.yan@arm.com>

On Wed, Apr 22, 2026 at 06:01:39PM +0100, Leo Yan wrote:
> Building on Debian sid with GCC 15 fails:

> GCC-15 defines NT_ARM_GCS in the toolchain headers, causing gcs-util.h
> to skip its fallback definition of struct user_gcs. This leads to the
> compiler error.

Are you sure it's GCC and not libc?  Anyway...

>  tools/testing/selftests/arm64/gcs/libc-gcs.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tools/testing/selftests/arm64/gcs/libc-gcs.c b/tools/testing/selftests/arm64/gcs/libc-gcs.c
> index 17b2fabfec386e523e788d8bcfcafa553c93bd9b..72e82bfbecc99e34da71d56cf5401c137d6e9a48 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>

Shouldn't this be in gcs-util.h where the local definition is?

On Wed, Apr 22, 2026 at 06:20:16PM +0100, Mark Brown wrote:

[...]

> > +++ 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>
> 
> Shouldn't this be in gcs-util.h where the local definition is?

Will update commit log and this one. Thanks for review!

Leo