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Message-Id: <20260117-nolibc-mysyscall-arm64-v1-1-f70266a3db15@weissschuh.net>
Date: Sat, 17 Jan 2026 13:10:51 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>, Shuah Khan <shuah@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kselftest@...r.kernel.org,
linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>,
Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH] kselftest/arm64: Use syscall() macro over nolibc
my_syscall()
The my_syscall*() macros are internal implementation details of nolibc.
Nolibc also provides the regular syscall(2), which is also a macro
and directly expands to the correct my_syscall().
Use syscall() instead.
As a side-effect this fixes some return value checks, as my_syscall()
returns the raw value as set by the kernel and does not set errno.
Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
Compile-tested only.
For the arm64 tree.
I want to rename those macros at some point.
---
tools/testing/selftests/arm64/abi/tpidr2.c | 3 +-
tools/testing/selftests/arm64/gcs/basic-gcs.c | 40 +++++++++++----------------
2 files changed, 17 insertions(+), 26 deletions(-)
diff --git a/tools/testing/selftests/arm64/abi/tpidr2.c b/tools/testing/selftests/arm64/abi/tpidr2.c
index 1703543fb7c7..ce4550fb7224 100644
--- a/tools/testing/selftests/arm64/abi/tpidr2.c
+++ b/tools/testing/selftests/arm64/abi/tpidr2.c
@@ -128,8 +128,7 @@ static int sys_clone(unsigned long clone_flags, unsigned long newsp,
int *parent_tidptr, unsigned long tls,
int *child_tidptr)
{
- return my_syscall5(__NR_clone, clone_flags, newsp, parent_tidptr, tls,
- child_tidptr);
+ return syscall(__NR_clone, clone_flags, newsp, parent_tidptr, tls, child_tidptr);
}
#define __STACK_SIZE (8 * 1024 * 1024)
diff --git a/tools/testing/selftests/arm64/gcs/basic-gcs.c b/tools/testing/selftests/arm64/gcs/basic-gcs.c
index 250977abc398..ae4cce6afe2b 100644
--- a/tools/testing/selftests/arm64/gcs/basic-gcs.c
+++ b/tools/testing/selftests/arm64/gcs/basic-gcs.c
@@ -22,7 +22,7 @@ static size_t page_size = 65536;
static __attribute__((noinline)) void valid_gcs_function(void)
{
/* Do something the compiler can't optimise out */
- my_syscall1(__NR_prctl, PR_SVE_GET_VL);
+ syscall(__NR_prctl, PR_SVE_GET_VL);
}
static inline int gcs_set_status(unsigned long mode)
@@ -36,12 +36,10 @@ static inline int gcs_set_status(unsigned long mode)
* other 3 values passed in registers to the syscall are zero
* since the kernel validates them.
*/
- ret = my_syscall5(__NR_prctl, PR_SET_SHADOW_STACK_STATUS, mode,
- 0, 0, 0);
+ ret = syscall(__NR_prctl, PR_SET_SHADOW_STACK_STATUS, mode, 0, 0, 0);
if (ret == 0) {
- ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS,
- &new_mode, 0, 0, 0);
+ ret = syscall(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &new_mode, 0, 0, 0);
if (ret == 0) {
if (new_mode != mode) {
ksft_print_msg("Mode set to %lx not %lx\n",
@@ -49,7 +47,7 @@ static inline int gcs_set_status(unsigned long mode)
ret = -EINVAL;
}
} else {
- ksft_print_msg("Failed to validate mode: %d\n", ret);
+ ksft_print_msg("Failed to validate mode: %d\n", errno);
}
if (enabling != chkfeat_gcs()) {
@@ -69,10 +67,9 @@ static bool read_status(void)
unsigned long state;
int ret;
- ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS,
- &state, 0, 0, 0);
+ ret = syscall(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &state, 0, 0, 0);
if (ret != 0) {
- ksft_print_msg("Failed to read state: %d\n", ret);
+ ksft_print_msg("Failed to read state: %d\n", errno);
return false;
}
@@ -188,9 +185,8 @@ static bool map_guarded_stack(void)
int elem;
bool pass = true;
- buf = (void *)my_syscall3(__NR_map_shadow_stack, 0, page_size,
- SHADOW_STACK_SET_MARKER |
- SHADOW_STACK_SET_TOKEN);
+ buf = (void *)syscall(__NR_map_shadow_stack, 0, page_size,
+ SHADOW_STACK_SET_MARKER | SHADOW_STACK_SET_TOKEN);
if (buf == MAP_FAILED) {
ksft_print_msg("Failed to map %lu byte GCS: %d\n",
page_size, errno);
@@ -257,8 +253,7 @@ static bool test_fork(void)
valid_gcs_function();
get_gcspr();
- ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS,
- &child_mode, 0, 0, 0);
+ ret = syscall(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &child_mode, 0, 0, 0);
if (ret == 0 && !(child_mode & PR_SHADOW_STACK_ENABLE)) {
ksft_print_msg("GCS not enabled in child\n");
ret = -EINVAL;
@@ -321,8 +316,7 @@ static bool test_vfork(void)
valid_gcs_function();
get_gcspr();
- ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS,
- &child_mode, 0, 0, 0);
+ ret = syscall(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &child_mode, 0, 0, 0);
if (ret == 0 && !(child_mode & PR_SHADOW_STACK_ENABLE)) {
ksft_print_msg("GCS not enabled in child\n");
ret = EXIT_FAILURE;
@@ -390,17 +384,15 @@ int main(void)
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);
+ ret = syscall(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &gcs_mode, 0, 0, 0);
if (ret != 0)
- ksft_exit_fail_msg("Failed to read GCS state: %d\n", ret);
+ ksft_exit_fail_msg("Failed to read GCS state: %d\n", errno);
if (!(gcs_mode & PR_SHADOW_STACK_ENABLE)) {
gcs_mode = PR_SHADOW_STACK_ENABLE;
- ret = my_syscall5(__NR_prctl, PR_SET_SHADOW_STACK_STATUS,
- gcs_mode, 0, 0, 0);
+ ret = syscall(__NR_prctl, PR_SET_SHADOW_STACK_STATUS, gcs_mode, 0, 0, 0);
if (ret != 0)
- ksft_exit_fail_msg("Failed to enable GCS: %d\n", ret);
+ ksft_exit_fail_msg("Failed to enable GCS: %d\n", errno);
}
ksft_set_plan(ARRAY_SIZE(tests));
@@ -410,9 +402,9 @@ int main(void)
}
/* One last test: disable GCS, we can do this one time */
- ret = my_syscall5(__NR_prctl, PR_SET_SHADOW_STACK_STATUS, 0, 0, 0, 0);
+ ret = syscall(__NR_prctl, PR_SET_SHADOW_STACK_STATUS, 0, 0, 0, 0);
if (ret != 0)
- ksft_print_msg("Failed to disable GCS: %d\n", ret);
+ ksft_print_msg("Failed to disable GCS: %d\n", errno);
ksft_finished();
---
base-commit: db81cecbeb215e764413dfc25489c30220f7241c
change-id: 20260117-nolibc-mysyscall-arm64-4eac243db7da
Best regards,
--
Thomas Weißschuh <linux@...ssschuh.net>
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