@@ -7,6 +7,10 @@
* Each test provides its own tde struct tdescr descriptor to link with
* this wrapper. Framework provides common helpers.
*/
+
+#include <sys/auxv.h>
+#include <sys/prctl.h>
+
#include <kselftest.h>
#include "test_signals.h"
@@ -16,6 +20,16 @@ struct tdescr *current = &tde;
int main(int argc, char *argv[])
{
+ /*
+ * Ensure GCS is at least enabled throughout the tests if
+ * supported, otherwise the inability to return from the
+ * function that enabled GCS makes it very inconvenient to set
+ * up test cases. The prctl() may fail if GCS was locked by
+ * libc setup code.
+ */
+ if (getauxval(AT_HWCAP2) & HWCAP2_GCS)
+ gcs_set_state(PR_SHADOW_STACK_ENABLE);
+
ksft_print_msg("%s :: %s\n", current->name, current->descr);
if (test_setup(current) && test_init(current)) {
test_run(current);
@@ -23,5 +37,6 @@ int main(int argc, char *argv[])
}
test_result(current);
- return current->result;
+ /* Do not return in case GCS was enabled */
+ exit(current->result);
}
@@ -18,6 +18,35 @@ void test_cleanup(struct tdescr *td);
int test_run(struct tdescr *td);
void test_result(struct tdescr *td);
+#ifndef __NR_prctl
+#define __NR_prctl 167
+#endif
+
+/*
+ * The prctl takes 1 argument but we need to ensure that the other
+ * values passed in registers to the syscall are zero since the kernel
+ * validates them.
+ */
+#define gcs_set_state(state) \
+ ({ \
+ register long _num __asm__ ("x8") = __NR_prctl; \
+ register long _arg1 __asm__ ("x0") = PR_SET_SHADOW_STACK_STATUS; \
+ register long _arg2 __asm__ ("x1") = (long)(state); \
+ register long _arg3 __asm__ ("x2") = 0; \
+ register long _arg4 __asm__ ("x3") = 0; \
+ register long _arg5 __asm__ ("x4") = 0; \
+ \
+ __asm__ volatile ( \
+ "svc #0\n" \
+ : "=r"(_arg1) \
+ : "r"(_arg1), "r"(_arg2), \
+ "r"(_arg3), "r"(_arg4), \
+ "r"(_arg5), "r"(_num) \
+ : "memory", "cc" \
+ ); \
+ _arg1; \
+ })
+
static inline bool feats_ok(struct tdescr *td)
{
if (td->feats_incompatible & td->feats_supported)