[PATCH 2/2] aarch64: Tests for locking GCS
Yury Khrustalev
yury.khrustalev@arm.com
Fri Dec 12 15:46:59 GMT 2025
Check that GCS is locked properly with the new tunable
glibc.cpu.aarch64_gcs_lock
---
sysdeps/unix/sysv/linux/aarch64/Makefile | 17 +++++
.../unix/sysv/linux/aarch64/tst-gcs-execv.c | 62 ++++++++++++++++++
.../sysv/linux/aarch64/tst-gcs-lock-static.c | 1 +
.../unix/sysv/linux/aarch64/tst-gcs-lock.c | 63 +++++++++++++++++++
.../linux/aarch64/tst-gcs-unlock-static.c | 2 +
.../unix/sysv/linux/aarch64/tst-gcs-unlock.c | 2 +
6 files changed, 147 insertions(+)
create mode 100644 sysdeps/unix/sysv/linux/aarch64/tst-gcs-execv.c
create mode 100644 sysdeps/unix/sysv/linux/aarch64/tst-gcs-lock-static.c
create mode 100644 sysdeps/unix/sysv/linux/aarch64/tst-gcs-lock.c
create mode 100644 sysdeps/unix/sysv/linux/aarch64/tst-gcs-unlock-static.c
create mode 100644 sysdeps/unix/sysv/linux/aarch64/tst-gcs-unlock.c
diff --git a/sysdeps/unix/sysv/linux/aarch64/Makefile b/sysdeps/unix/sysv/linux/aarch64/Makefile
index 6741f8ec00..8938ef68a0 100644
--- a/sysdeps/unix/sysv/linux/aarch64/Makefile
+++ b/sysdeps/unix/sysv/linux/aarch64/Makefile
@@ -28,6 +28,8 @@ gcs-tests-dynamic = \
tst-gcs-dlopen-override \
tst-gcs-enforced \
tst-gcs-enforced-abort \
+ tst-gcs-execv \
+ tst-gcs-lock \
tst-gcs-noreturn \
tst-gcs-optional-off \
tst-gcs-optional-on \
@@ -36,15 +38,18 @@ gcs-tests-dynamic = \
tst-gcs-shared-enforced-abort \
tst-gcs-shared-optional \
tst-gcs-shared-override \
+ tst-gcs-unlock \
# gcs-tests-dynamic
gcs-tests-static = \
tst-gcs-disabled-static \
tst-gcs-enforced-static \
tst-gcs-enforced-static-abort \
+ tst-gcs-lock-static \
tst-gcs-optional-static-off \
tst-gcs-optional-static-on \
tst-gcs-override-static \
+ tst-gcs-unlock-static \
# gcs-tests-static
tests += \
@@ -94,6 +99,18 @@ tst-gcs-optional-static-on-ENV = GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=2
tst-gcs-optional-static-off-ENV = GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=2
tst-gcs-override-static-ENV = GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=3
+LDFLAGS-tst-gcs-lock += -Wl,-z,gcs=always
+LDFLAGS-tst-gcs-lock-static += -Wl,-z,gcs=always
+LDFLAGS-tst-gcs-unlock += -Wl,-z,gcs=always
+LDFLAGS-tst-gcs-unlock-static += -Wl,-z,gcs=always
+tst-gcs-lock-ENV = GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=1
+tst-gcs-lock-static-ENV = GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=1
+tst-gcs-unlock-ENV = GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=1:glibc.cpu.aarch64_gcs_lock=0
+tst-gcs-unlock-static-ENV = GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=1:glibc.cpu.aarch64_gcs_lock=0
+
+LDFLAGS-tst-gcs-execv += -Wl,-z,gcs=always
+tst-gcs-execv-ENV = GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=1:glibc.cpu.aarch64_gcs_lock=1
+
# force one of the dependencies to be unmarked
LDFLAGS-tst-gcs-mod2.so += -Wl,-z,gcs=never
diff --git a/sysdeps/unix/sysv/linux/aarch64/tst-gcs-execv.c b/sysdeps/unix/sysv/linux/aarch64/tst-gcs-execv.c
new file mode 100644
index 0000000000..d4ac2ccc02
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/aarch64/tst-gcs-execv.c
@@ -0,0 +1,62 @@
+/* AArch64 test for GCS for creating child process.
+ Copyright (C) 2025 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include "tst-gcs-helper.h"
+
+#include <linux/prctl.h>
+#include <sys/prctl.h>
+#include <unistd.h>
+#include <errno.h>
+
+#ifndef PR_SET_SHADOW_STACK_STATUS
+# define PR_SET_SHADOW_STACK_STATUS 75
+#endif
+
+static int
+do_test_argv (int argc, char **argv)
+{
+ /* Check if GCS could possible by enabled. */
+ if (!(getauxval (AT_HWCAP) & HWCAP_GCS))
+ FAIL_UNSUPPORTED ("kernel or CPU does not support GCS");
+
+ /* GCS should be enabled for this test at the start. */
+ TEST_VERIFY (__check_gcs_status ());
+
+ if (argc == 1)
+ {
+ printf ("in parent: %u\n", getpid ());
+ /* Spawn child process. */
+ char *args[] = { argv[0], (char *)"child", NULL };
+ execv (args[0], args);
+ FAIL_EXIT1 ("execv: %m");
+ }
+
+ /* In child. */
+ printf ("in child: %u\n", getpid ());
+ TEST_VERIFY (__check_gcs_status ());
+
+ /* Try disabling GCS (should fail with EBUSY). */
+ int res = prctl (PR_SET_SHADOW_STACK_STATUS, 0, 0, 0, 0);
+ TEST_COMPARE (res, -1);
+ TEST_COMPARE (errno, EBUSY);
+ perror ("prctl could not disable GCS");
+ return 0;
+}
+
+#define TEST_FUNCTION_ARGV do_test_argv
+#include <support/test-driver.c>
diff --git a/sysdeps/unix/sysv/linux/aarch64/tst-gcs-lock-static.c b/sysdeps/unix/sysv/linux/aarch64/tst-gcs-lock-static.c
new file mode 100644
index 0000000000..b80e2f70e8
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/aarch64/tst-gcs-lock-static.c
@@ -0,0 +1 @@
+#include "tst-gcs-lock.c"
diff --git a/sysdeps/unix/sysv/linux/aarch64/tst-gcs-lock.c b/sysdeps/unix/sysv/linux/aarch64/tst-gcs-lock.c
new file mode 100644
index 0000000000..8d3a56e38c
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/aarch64/tst-gcs-lock.c
@@ -0,0 +1,63 @@
+/* AArch64 test for GCS locking.
+ Copyright (C) 2025 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include "tst-gcs-helper.h"
+
+#include <linux/prctl.h>
+#include <sys/prctl.h>
+#include <errno.h>
+
+#ifndef PR_SET_SHADOW_STACK_STATUS
+# define PR_SET_SHADOW_STACK_STATUS 75
+#endif
+
+static int
+do_test (void)
+{
+ /* Check if GCS could possible by enabled. */
+ if (!(getauxval (AT_HWCAP) & HWCAP_GCS))
+ FAIL_UNSUPPORTED ("kernel or CPU does not support GCS");
+
+ TEST_VERIFY (__check_gcs_status ());
+
+ /* Try disabling GCS. */
+ int res = prctl (PR_SET_SHADOW_STACK_STATUS, 0, 0, 0, 0);
+ if (res)
+ {
+ TEST_COMPARE (errno, EBUSY);
+ perror ("prctl");
+#ifdef GCS_SHOULD_UNLOCK
+ FAIL_EXIT1 ("GCS was not unlocked (was supposed to)");
+#else
+ TEST_VERIFY (__check_gcs_status ());
+#endif
+ }
+ else
+ {
+#ifdef GCS_SHOULD_UNLOCK
+ TEST_VERIFY (!__check_gcs_status ());
+ puts ("GCS unlocked successfully");
+#else
+ FAIL_EXIT1 ("GCS was unlocked (was not supposed to)");
+#endif
+ }
+
+ return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/unix/sysv/linux/aarch64/tst-gcs-unlock-static.c b/sysdeps/unix/sysv/linux/aarch64/tst-gcs-unlock-static.c
new file mode 100644
index 0000000000..7e02820031
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/aarch64/tst-gcs-unlock-static.c
@@ -0,0 +1,2 @@
+#define GCS_SHOULD_UNLOCK
+#include "tst-gcs-lock.c"
diff --git a/sysdeps/unix/sysv/linux/aarch64/tst-gcs-unlock.c b/sysdeps/unix/sysv/linux/aarch64/tst-gcs-unlock.c
new file mode 100644
index 0000000000..7e02820031
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/aarch64/tst-gcs-unlock.c
@@ -0,0 +1,2 @@
+#define GCS_SHOULD_UNLOCK
+#include "tst-gcs-lock.c"
--
2.47.3
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