[PATCH v9 28/39] kselftest: Provide shadow stack enable helpers for arm64

[Mark Brown <broonie@kernel.org>]

Allow test programs to use the shadow stack helpers on arm64.

Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 tools/testing/selftests/ksft_shstk.h | 37 ++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/tools/testing/selftests/ksft_shstk.h b/tools/testing/selftests/ksft_shstk.h
index 85d0747c1802..302957a0bbd5 100644
--- a/tools/testing/selftests/ksft_shstk.h
+++ b/tools/testing/selftests/ksft_shstk.h
@@ -50,6 +50,43 @@ static inline __attribute__((always_inline)) void enable_shadow_stack(void)
 
 #endif
 
+#ifdef __aarch64__
+#define PR_SET_SHADOW_STACK_STATUS      75
+# define PR_SHADOW_STACK_ENABLE         (1UL << 0)
+
+#define my_syscall2(num, arg1, arg2)                                          \
+({                                                                            \
+	register long _num  __asm__ ("x8") = (num);                           \
+	register long _arg1 __asm__ ("x0") = (long)(arg1);                    \
+	register long _arg2 __asm__ ("x1") = (long)(arg2);                    \
+	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;                                                                \
+})
+
+#define ENABLE_SHADOW_STACK
+static inline __attribute__((always_inline))  void enable_shadow_stack(void)
+{
+	int ret;
+
+	ret = my_syscall2(__NR_prctl, PR_SET_SHADOW_STACK_STATUS,
+			  PR_SHADOW_STACK_ENABLE);
+	if (ret == 0)
+		shadow_stack_enabled = true;
+}
+
+#endif
+
 #ifndef __NR_map_shadow_stack
 #define __NR_map_shadow_stack 453
 #endif

-- 
2.39.2