@@ -4,7 +4,7 @@
ARCH ?= $(shell uname -m 2>/dev/null || echo not)
ifneq (,$(filter $(ARCH),aarch64 arm64))
-ARM64_SUBTARGETS ?= tags signal
+ARM64_SUBTARGETS ?= tags signal pauth
else
ARM64_SUBTARGETS :=
endif
new file mode 100644
@@ -0,0 +1 @@
+pac
new file mode 100644
@@ -0,0 +1,32 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2020 ARM Limited
+
+# preserve CC value from top level Makefile
+ifeq ($(CC),cc)
+CC := $(CROSS_COMPILE)gcc
+endif
+
+CFLAGS += -mbranch-protection=pac-ret
+# check if the compiler supports ARMv8.3 and branch protection with PAuth
+pauth_cc_support := $(shell if ($(CC) $(CFLAGS) -march=armv8.3-a -E -x c /dev/null -o /dev/null 2>&1) then echo "1"; fi)
+
+ifeq ($(pauth_cc_support),1)
+TEST_GEN_PROGS := pac
+TEST_GEN_FILES := pac_corruptor.o
+endif
+
+include ../../lib.mk
+
+ifeq ($(pauth_cc_support),1)
+# pac* and aut* instructions are not available on architectures berfore
+# ARMv8.3. Therefore target ARMv8.3 wherever they are used directly
+$(OUTPUT)/pac_corruptor.o: pac_corruptor.S
+ $(CC) -c $^ -o $@ $(CFLAGS) -march=armv8.3-a
+
+# when -mbranch-protection is enabled and the target architecture is ARMv8.3 or
+# greater, gcc emits pac* instructions which are not in HINT NOP space,
+# preventing the tests from occurring at all. Compile for ARMv8.2 so tests can
+# run on earlier targets and print a meaningful error messages
+$(OUTPUT)/pac: pac.c $(OUTPUT)/pac_corruptor.o
+ $(CC) $^ -o $@ $(CFLAGS) -march=armv8.2-a
+endif
new file mode 100644
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2020 ARM Limited */
+
+#ifndef _HELPER_H_
+#define _HELPER_H_
+
+void pac_corruptor(void);
+
+#endif
new file mode 100644
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2020 ARM Limited
+
+#include <sys/auxv.h>
+#include <signal.h>
+#include <setjmp.h>
+
+#include "../../kselftest_harness.h"
+#include "helper.h"
+
+#define ASSERT_PAUTH_ENABLED() \
+do { \
+ unsigned long hwcaps = getauxval(AT_HWCAP); \
+ /* data key instructions are not in NOP space. This prevents a SIGILL */ \
+ ASSERT_NE(0, hwcaps & HWCAP_PACA) TH_LOG("PAUTH not enabled"); \
+} while (0)
+
+sigjmp_buf jmpbuf;
+void pac_signal_handler(int signum, siginfo_t *si, void *uc)
+{
+ if (signum == SIGSEGV || signum == SIGILL)
+ siglongjmp(jmpbuf, 1);
+}
+
+/* check that a corrupted PAC results in SIGSEGV or SIGILL */
+TEST(corrupt_pac)
+{
+ struct sigaction sa;
+
+ ASSERT_PAUTH_ENABLED();
+ if (sigsetjmp(jmpbuf, 1) == 0) {
+ sa.sa_sigaction = pac_signal_handler;
+ sa.sa_flags = SA_SIGINFO | SA_RESETHAND;
+ sigemptyset(&sa.sa_mask);
+
+ sigaction(SIGSEGV, &sa, NULL);
+ sigaction(SIGILL, &sa, NULL);
+
+ pac_corruptor();
+ ASSERT_TRUE(0) TH_LOG("SIGSEGV/SIGILL signal did not occur");
+ }
+}
+
+TEST_HARNESS_MAIN
new file mode 100644
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2020 ARM Limited */
+
+.global pac_corruptor
+
+.text
+/*
+ * Corrupting a single bit of the PAC ensures the authentication will fail. It
+ * also guarantees no possible collision. TCR_EL1.TBI0 is set by default so no
+ * top byte PAC is tested
+ */
+ pac_corruptor:
+ paciasp
+
+ /* corrupt the top bit of the PAC */
+ eor lr, lr, #1 << 53
+
+ autiasp
+ ret