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-rw-r--r--tools/testing/selftests/arm64/Makefile2
-rw-r--r--tools/testing/selftests/arm64/bti/.gitignore2
-rw-r--r--tools/testing/selftests/arm64/bti/Makefile61
-rw-r--r--tools/testing/selftests/arm64/bti/assembler.h80
-rw-r--r--tools/testing/selftests/arm64/bti/btitest.h23
-rw-r--r--tools/testing/selftests/arm64/bti/compiler.h21
-rw-r--r--tools/testing/selftests/arm64/bti/gen/.gitignore2
-rw-r--r--tools/testing/selftests/arm64/bti/signal.c37
-rw-r--r--tools/testing/selftests/arm64/bti/signal.h21
-rw-r--r--tools/testing/selftests/arm64/bti/start.S14
-rw-r--r--tools/testing/selftests/arm64/bti/syscall.S23
-rw-r--r--tools/testing/selftests/arm64/bti/system.c22
-rw-r--r--tools/testing/selftests/arm64/bti/system.h28
-rw-r--r--tools/testing/selftests/arm64/bti/test.c234
-rw-r--r--tools/testing/selftests/arm64/bti/teststubs.S39
-rw-r--r--tools/testing/selftests/arm64/bti/trampoline.S29
-rw-r--r--tools/testing/selftests/arm64/mte/Makefile15
-rw-r--r--tools/testing/selftests/arm64/mte/check_ksm_options.c5
-rw-r--r--tools/testing/selftests/arm64/mte/check_user_mem.c3
-rw-r--r--tools/testing/selftests/arm64/mte/mte_common_util.c39
20 files changed, 676 insertions, 24 deletions
diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/selftests/arm64/Makefile
index 2c9d012797a7..ced910fb4019 100644
--- a/tools/testing/selftests/arm64/Makefile
+++ b/tools/testing/selftests/arm64/Makefile
@@ -4,7 +4,7 @@
 ARCH ?= $(shell uname -m 2>/dev/null || echo not)
 
 ifneq (,$(filter $(ARCH),aarch64 arm64))
-ARM64_SUBTARGETS ?= tags signal pauth fp mte
+ARM64_SUBTARGETS ?= tags signal pauth fp mte bti
 else
 ARM64_SUBTARGETS :=
 endif
diff --git a/tools/testing/selftests/arm64/bti/.gitignore b/tools/testing/selftests/arm64/bti/.gitignore
new file mode 100644
index 000000000000..73869fabada4
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/.gitignore
@@ -0,0 +1,2 @@
+btitest
+nobtitest
diff --git a/tools/testing/selftests/arm64/bti/Makefile b/tools/testing/selftests/arm64/bti/Makefile
new file mode 100644
index 000000000000..73e013c082a6
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/Makefile
@@ -0,0 +1,61 @@
+# SPDX-License-Identifier: GPL-2.0
+
+TEST_GEN_PROGS := btitest nobtitest
+
+PROGS := $(patsubst %,gen/%,$(TEST_GEN_PROGS))
+
+# These tests are built as freestanding binaries since otherwise BTI
+# support in ld.so is required which is not currently widespread; when
+# it is available it will still be useful to test this separately as the
+# cases for statically linked and dynamically lined binaries are
+# slightly different.
+
+CFLAGS_NOBTI = -DBTI=0
+CFLAGS_BTI = -mbranch-protection=standard -DBTI=1
+
+CFLAGS_COMMON = -ffreestanding -Wall -Wextra $(CFLAGS)
+
+BTI_CC_COMMAND = $(CC) $(CFLAGS_BTI) $(CFLAGS_COMMON) -c -o $@ $<
+NOBTI_CC_COMMAND = $(CC) $(CFLAGS_NOBTI) $(CFLAGS_COMMON) -c -o $@ $<
+
+%-bti.o: %.c
+	$(BTI_CC_COMMAND)
+
+%-bti.o: %.S
+	$(BTI_CC_COMMAND)
+
+%-nobti.o: %.c
+	$(NOBTI_CC_COMMAND)
+
+%-nobti.o: %.S
+	$(NOBTI_CC_COMMAND)
+
+BTI_OBJS =                                      \
+	test-bti.o                           \
+	signal-bti.o                            \
+	start-bti.o                             \
+	syscall-bti.o                           \
+	system-bti.o                            \
+	teststubs-bti.o                         \
+	trampoline-bti.o
+gen/btitest: $(BTI_OBJS)
+	$(CC) $(CFLAGS_BTI) $(CFLAGS_COMMON) -nostdlib -o $@ $^
+
+NOBTI_OBJS =                                    \
+	test-nobti.o                         \
+	signal-nobti.o                          \
+	start-nobti.o                           \
+	syscall-nobti.o                         \
+	system-nobti.o                          \
+	teststubs-nobti.o                       \
+	trampoline-nobti.o
+gen/nobtitest: $(NOBTI_OBJS)
+	$(CC) $(CFLAGS_BTI) $(CFLAGS_COMMON) -nostdlib -o $@ $^
+
+# Including KSFT lib.mk here will also mangle the TEST_GEN_PROGS list
+# to account for any OUTPUT target-dirs optionally provided by
+# the toplevel makefile
+include ../../lib.mk
+
+$(TEST_GEN_PROGS): $(PROGS)
+	cp $(PROGS) $(OUTPUT)/
diff --git a/tools/testing/selftests/arm64/bti/assembler.h b/tools/testing/selftests/arm64/bti/assembler.h
new file mode 100644
index 000000000000..04e7b72880ef
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/assembler.h
@@ -0,0 +1,80 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019  Arm Limited
+ * Original author: Dave Martin <Dave.Martin@arm.com>
+ */
+
+#ifndef ASSEMBLER_H
+#define ASSEMBLER_H
+
+#define NT_GNU_PROPERTY_TYPE_0	5
+#define GNU_PROPERTY_AARCH64_FEATURE_1_AND	0xc0000000
+
+/* Bits for GNU_PROPERTY_AARCH64_FEATURE_1_BTI */
+#define GNU_PROPERTY_AARCH64_FEATURE_1_BTI	(1U << 0)
+#define GNU_PROPERTY_AARCH64_FEATURE_1_PAC	(1U << 1)
+
+
+.macro startfn name:req
+	.globl \name
+\name:
+	.macro endfn
+		.size \name, . - \name
+		.type \name, @function
+		.purgem endfn
+	.endm
+.endm
+
+.macro emit_aarch64_feature_1_and
+	.pushsection .note.gnu.property, "a"
+	.align	3
+	.long	2f - 1f
+	.long	6f - 3f
+	.long	NT_GNU_PROPERTY_TYPE_0
+1:	.string	"GNU"
+2:
+	.align	3
+3:	.long	GNU_PROPERTY_AARCH64_FEATURE_1_AND
+	.long	5f - 4f
+4:
+#if BTI
+	.long	GNU_PROPERTY_AARCH64_FEATURE_1_PAC | \
+		GNU_PROPERTY_AARCH64_FEATURE_1_BTI
+#else
+	.long	0
+#endif
+5:
+	.align	3
+6:
+	.popsection
+.endm
+
+.macro paciasp
+	hint	0x19
+.endm
+
+.macro autiasp
+	hint	0x1d
+.endm
+
+.macro __bti_
+	hint	0x20
+.endm
+
+.macro __bti_c
+	hint	0x22
+.endm
+
+.macro __bti_j
+	hint	0x24
+.endm
+
+.macro __bti_jc
+	hint	0x26
+.endm
+
+.macro bti what=
+	__bti_\what
+.endm
+
+#endif /* ! ASSEMBLER_H */
diff --git a/tools/testing/selftests/arm64/bti/btitest.h b/tools/testing/selftests/arm64/bti/btitest.h
new file mode 100644
index 000000000000..2aff9b10336e
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/btitest.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019  Arm Limited
+ * Original author: Dave Martin <Dave.Martin@arm.com>
+ */
+
+#ifndef BTITEST_H
+#define BTITEST_H
+
+/* Trampolines for calling the test stubs: */
+void call_using_br_x0(void (*)(void));
+void call_using_br_x16(void (*)(void));
+void call_using_blr(void (*)(void));
+
+/* Test stubs: */
+void nohint_func(void);
+void bti_none_func(void);
+void bti_c_func(void);
+void bti_j_func(void);
+void bti_jc_func(void);
+void paciasp_func(void);
+
+#endif /* !BTITEST_H */
diff --git a/tools/testing/selftests/arm64/bti/compiler.h b/tools/testing/selftests/arm64/bti/compiler.h
new file mode 100644
index 000000000000..ebb6204f447a
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/compiler.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019  Arm Limited
+ * Original author: Dave Martin <Dave.Martin@arm.com>
+ */
+
+#ifndef COMPILER_H
+#define COMPILER_H
+
+#define __always_unused __attribute__((__unused__))
+#define __noreturn __attribute__((__noreturn__))
+#define __unreachable() __builtin_unreachable()
+
+/* curse(e) has value e, but the compiler cannot assume so */
+#define curse(e) ({				\
+	__typeof__(e) __curse_e = (e);		\
+	asm ("" : "+r" (__curse_e));		\
+	__curse_e;				\
+})
+
+#endif /* ! COMPILER_H */
diff --git a/tools/testing/selftests/arm64/bti/gen/.gitignore b/tools/testing/selftests/arm64/bti/gen/.gitignore
new file mode 100644
index 000000000000..73869fabada4
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/gen/.gitignore
@@ -0,0 +1,2 @@
+btitest
+nobtitest
diff --git a/tools/testing/selftests/arm64/bti/signal.c b/tools/testing/selftests/arm64/bti/signal.c
new file mode 100644
index 000000000000..f3fd29b91141
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/signal.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019  Arm Limited
+ * Original author: Dave Martin <Dave.Martin@arm.com>
+ */
+
+#include "system.h"
+#include "signal.h"
+
+int sigemptyset(sigset_t *s)
+{
+	unsigned int i;
+
+	for (i = 0; i < _NSIG_WORDS; ++i)
+		s->sig[i] = 0;
+
+	return 0;
+}
+
+int sigaddset(sigset_t *s, int n)
+{
+	if (n < 1 || n > _NSIG)
+		return -EINVAL;
+
+	s->sig[(n - 1) / _NSIG_BPW] |= 1UL << (n - 1) % _NSIG_BPW;
+	return 0;
+}
+
+int sigaction(int n, struct sigaction *sa, const struct sigaction *old)
+{
+	return syscall(__NR_rt_sigaction, n, sa, old, sizeof(sa->sa_mask));
+}
+
+int sigprocmask(int how, const sigset_t *mask, sigset_t *old)
+{
+	return syscall(__NR_rt_sigprocmask, how, mask, old, sizeof(*mask));
+}
diff --git a/tools/testing/selftests/arm64/bti/signal.h b/tools/testing/selftests/arm64/bti/signal.h
new file mode 100644
index 000000000000..103457dc880e
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/signal.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019  Arm Limited
+ * Original author: Dave Martin <Dave.Martin@arm.com>
+ */
+
+#ifndef SIGNAL_H
+#define SIGNAL_H
+
+#include <linux/signal.h>
+
+#include "system.h"
+
+typedef __sighandler_t sighandler_t;
+
+int sigemptyset(sigset_t *s);
+int sigaddset(sigset_t *s, int n);
+int sigaction(int n, struct sigaction *sa, const struct sigaction *old);
+int sigprocmask(int how, const sigset_t *mask, sigset_t *old);
+
+#endif /* ! SIGNAL_H */
diff --git a/tools/testing/selftests/arm64/bti/start.S b/tools/testing/selftests/arm64/bti/start.S
new file mode 100644
index 000000000000..831f952e0572
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/start.S
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019  Arm Limited
+ * Original author: Dave Martin <Dave.Martin@arm.com>
+ */
+
+#include "assembler.h"
+
+startfn _start
+	mov	x0, sp
+	b	start
+endfn
+
+emit_aarch64_feature_1_and
diff --git a/tools/testing/selftests/arm64/bti/syscall.S b/tools/testing/selftests/arm64/bti/syscall.S
new file mode 100644
index 000000000000..8dde8b6f3db1
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/syscall.S
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019  Arm Limited
+ * Original author: Dave Martin <Dave.Martin@arm.com>
+ */
+
+#include "assembler.h"
+
+startfn syscall
+	bti	c
+	mov	w8, w0
+	mov	x0, x1
+	mov	x1, x2
+	mov	x2, x3
+	mov	x3, x4
+	mov	x4, x5
+	mov	x5, x6
+	mov	x6, x7
+	svc	#0
+	ret
+endfn
+
+emit_aarch64_feature_1_and
diff --git a/tools/testing/selftests/arm64/bti/system.c b/tools/testing/selftests/arm64/bti/system.c
new file mode 100644
index 000000000000..6385d8d4973b
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/system.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019  Arm Limited
+ * Original author: Dave Martin <Dave.Martin@arm.com>
+ */
+
+#include "system.h"
+
+#include <asm/unistd.h>
+
+#include "compiler.h"
+
+void __noreturn exit(int n)
+{
+	syscall(__NR_exit, n);
+	__unreachable();
+}
+
+ssize_t write(int fd, const void *buf, size_t size)
+{
+	return syscall(__NR_write, fd, buf, size);
+}
diff --git a/tools/testing/selftests/arm64/bti/system.h b/tools/testing/selftests/arm64/bti/system.h
new file mode 100644
index 000000000000..aca118589705
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/system.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019  Arm Limited
+ * Original author: Dave Martin <Dave.Martin@arm.com>
+ */
+
+#ifndef SYSTEM_H
+#define SYSTEM_H
+
+#include <linux/types.h>
+#include <linux/stddef.h>
+
+typedef __kernel_size_t size_t;
+typedef __kernel_ssize_t ssize_t;
+
+#include <linux/errno.h>
+#include <asm/hwcap.h>
+#include <asm/ptrace.h>
+#include <asm/unistd.h>
+
+#include "compiler.h"
+
+long syscall(int nr, ...);
+
+void __noreturn exit(int n);
+ssize_t write(int fd, const void *buf, size_t size);
+
+#endif /* ! SYSTEM_H */
diff --git a/tools/testing/selftests/arm64/bti/test.c b/tools/testing/selftests/arm64/bti/test.c
new file mode 100644
index 000000000000..656b04976ccc
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/test.c
@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019,2021  Arm Limited
+ * Original author: Dave Martin <Dave.Martin@arm.com>
+ */
+
+#include "system.h"
+
+#include <linux/errno.h>
+#include <linux/auxvec.h>
+#include <linux/signal.h>
+#include <asm/sigcontext.h>
+#include <asm/ucontext.h>
+
+typedef struct ucontext ucontext_t;
+
+#include "btitest.h"
+#include "compiler.h"
+#include "signal.h"
+
+#define EXPECTED_TESTS 18
+
+static volatile unsigned int test_num = 1;
+static unsigned int test_passed;
+static unsigned int test_failed;
+static unsigned int test_skipped;
+
+static void fdputs(int fd, const char *str)
+{
+	size_t len = 0;
+	const char *p = str;
+
+	while (*p++)
+		++len;
+
+	write(fd, str, len);
+}
+
+static void putstr(const char *str)
+{
+	fdputs(1, str);
+}
+
+static void putnum(unsigned int num)
+{
+	char c;
+
+	if (num / 10)
+		putnum(num / 10);
+
+	c = '0' + (num % 10);
+	write(1, &c, 1);
+}
+
+#define puttestname(test_name, trampoline_name) do {	\
+	putstr(test_name);				\
+	putstr("/");					\
+	putstr(trampoline_name);			\
+} while (0)
+
+void print_summary(void)
+{
+	putstr("# Totals: pass:");
+	putnum(test_passed);
+	putstr(" fail:");
+	putnum(test_failed);
+	putstr(" xfail:0 xpass:0 skip:");
+	putnum(test_skipped);
+	putstr(" error:0\n");
+}
+
+static const char *volatile current_test_name;
+static const char *volatile current_trampoline_name;
+static volatile int sigill_expected, sigill_received;
+
+static void handler(int n, siginfo_t *si __always_unused,
+		    void *uc_ __always_unused)
+{
+	ucontext_t *uc = uc_;
+
+	putstr("# \t[SIGILL in ");
+	puttestname(current_test_name, current_trampoline_name);
+	putstr(", BTYPE=");
+	write(1, &"00011011"[((uc->uc_mcontext.pstate & PSR_BTYPE_MASK)
+			      >> PSR_BTYPE_SHIFT) * 2], 2);
+	if (!sigill_expected) {
+		putstr("]\n");
+		putstr("not ok ");
+		putnum(test_num);
+		putstr(" ");
+		puttestname(current_test_name, current_trampoline_name);
+		putstr("(unexpected SIGILL)\n");
+		print_summary();
+		exit(128 + n);
+	}
+
+	putstr(" (expected)]\n");
+	sigill_received = 1;
+	/* zap BTYPE so that resuming the faulting code will work */
+	uc->uc_mcontext.pstate &= ~PSR_BTYPE_MASK;
+}
+
+static int skip_all;
+
+static void __do_test(void (*trampoline)(void (*)(void)),
+		      void (*fn)(void),
+		      const char *trampoline_name,
+		      const char *name,
+		      int expect_sigill)
+{
+	if (skip_all) {
+		test_skipped++;
+		putstr("ok ");
+		putnum(test_num);
+		putstr(" ");
+		puttestname(name, trampoline_name);
+		putstr(" # SKIP\n");
+
+		return;
+	}
+
+	/* Branch Target exceptions should only happen in BTI binaries: */
+	if (!BTI)
+		expect_sigill = 0;
+
+	sigill_expected = expect_sigill;
+	sigill_received = 0;
+	current_test_name = name;
+	current_trampoline_name = trampoline_name;
+
+	trampoline(fn);
+
+	if (expect_sigill && !sigill_received) {
+		putstr("not ok ");
+		test_failed++;
+	} else {
+		putstr("ok ");
+		test_passed++;
+	}
+	putnum(test_num++);
+	putstr(" ");
+	puttestname(name, trampoline_name);
+	putstr("\n");
+}
+
+#define do_test(expect_sigill_br_x0,					\
+		expect_sigill_br_x16,					\
+		expect_sigill_blr,					\
+		name)							\
+do {									\
+	__do_test(call_using_br_x0, name, "call_using_br_x0", #name,	\
+		  expect_sigill_br_x0);					\
+	__do_test(call_using_br_x16, name, "call_using_br_x16", #name,	\
+		  expect_sigill_br_x16);				\
+	__do_test(call_using_blr, name, "call_using_blr", #name,	\
+		  expect_sigill_blr);					\
+} while (0)
+
+void start(int *argcp)
+{
+	struct sigaction sa;
+	void *const *p;
+	const struct auxv_entry {
+		unsigned long type;
+		unsigned long val;
+	} *auxv;
+	unsigned long hwcap = 0, hwcap2 = 0;
+
+	putstr("TAP version 13\n");
+	putstr("1..");
+	putnum(EXPECTED_TESTS);
+	putstr("\n");
+
+	/* Gross hack for finding AT_HWCAP2 from the initial process stack: */
+	p = (void *const *)argcp + 1 + *argcp + 1; /* start of environment */
+	/* step over environment */
+	while (*p++)
+		;
+	for (auxv = (const struct auxv_entry *)p; auxv->type != AT_NULL; ++auxv) {
+		switch (auxv->type) {
+		case AT_HWCAP:
+			hwcap = auxv->val;
+			break;
+		case AT_HWCAP2:
+			hwcap2 = auxv->val;
+			break;
+		default:
+			break;
+		}
+	}
+
+	if (hwcap & HWCAP_PACA)
+		putstr("# HWCAP_PACA present\n");
+	else
+		putstr("# HWCAP_PACA not present\n");
+
+	if (hwcap2 & HWCAP2_BTI) {
+		putstr("# HWCAP2_BTI present\n");
+		if (!(hwcap & HWCAP_PACA))
+			putstr("# Bad hardware?  Expect problems.\n");
+	} else {
+		putstr("# HWCAP2_BTI not present\n");
+		skip_all = 1;
+	}
+
+	putstr("# Test binary");
+	if (!BTI)
+		putstr(" not");
+	putstr(" built for BTI\n");
+
+	sa.sa_handler = (sighandler_t)(void *)handler;
+	sa.sa_flags = SA_SIGINFO;
+	sigemptyset(&sa.sa_mask);
+	sigaction(SIGILL, &sa, NULL);
+	sigaddset(&sa.sa_mask, SIGILL);
+	sigprocmask(SIG_UNBLOCK, &sa.sa_mask, NULL);
+
+	do_test(1, 1, 1, nohint_func);
+	do_test(1, 1, 1, bti_none_func);
+	do_test(1, 0, 0, bti_c_func);
+	do_test(0, 0, 1, bti_j_func);
+	do_test(0, 0, 0, bti_jc_func);
+	do_test(1, 0, 0, paciasp_func);
+
+	print_summary();
+
+	if (test_num - 1 != EXPECTED_TESTS)
+		putstr("# WARNING - EXPECTED TEST COUNT WRONG\n");
+
+	if (test_failed)
+		exit(1);
+	else
+		exit(0);
+}
diff --git a/tools/testing/selftests/arm64/bti/teststubs.S b/tools/testing/selftests/arm64/bti/teststubs.S
new file mode 100644
index 000000000000..b62c8c35f67e
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/teststubs.S
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019  Arm Limited
+ * Original author: Dave Martin <Dave.Martin@arm.com>
+ */
+
+#include "assembler.h"
+
+startfn bti_none_func
+	bti
+	ret
+endfn
+
+startfn bti_c_func
+	bti	c
+	ret
+endfn
+
+startfn bti_j_func
+	bti	j
+	ret
+endfn
+
+startfn bti_jc_func
+	bti	jc
+	ret
+endfn
+
+startfn paciasp_func
+	paciasp
+	autiasp
+	ret
+endfn
+
+startfn nohint_func
+	ret
+endfn
+
+emit_aarch64_feature_1_and
diff --git a/tools/testing/selftests/arm64/bti/trampoline.S b/tools/testing/selftests/arm64/bti/trampoline.S
new file mode 100644
index 000000000000..09beb3f361f1
--- /dev/null
+++ b/tools/testing/selftests/arm64/bti/trampoline.S
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019  Arm Limited
+ * Original author: Dave Martin <Dave.Martin@arm.com>
+ */
+
+#include "assembler.h"
+
+startfn call_using_br_x0
+	bti	c
+	br	x0
+endfn
+
+startfn call_using_br_x16
+	bti	c
+	mov	x16, x0
+	br	x16
+endfn
+
+startfn call_using_blr
+	paciasp
+	stp	x29, x30, [sp, #-16]!
+	blr	x0
+	ldp	x29, x30, [sp], #16
+	autiasp
+	ret
+endfn
+
+emit_aarch64_feature_1_and
diff --git a/tools/testing/selftests/arm64/mte/Makefile b/tools/testing/selftests/arm64/mte/Makefile
index 0b3af552632a..409e3e53d00a 100644
--- a/tools/testing/selftests/arm64/mte/Makefile
+++ b/tools/testing/selftests/arm64/mte/Makefile
@@ -1,14 +1,18 @@
 # SPDX-License-Identifier: GPL-2.0
 # Copyright (C) 2020 ARM Limited
 
-CFLAGS += -std=gnu99 -I. -lpthread
+# preserve CC value from top level Makefile
+ifeq ($(CC),cc)
+CC := $(CROSS_COMPILE)gcc
+endif
+
+CFLAGS += -std=gnu99 -I. -pthread
+LDFLAGS += -pthread
 SRCS := $(filter-out mte_common_util.c,$(wildcard *.c))
 PROGS := $(patsubst %.c,%,$(SRCS))
 
 #Add mte compiler option
-ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep gcc),)
 CFLAGS += -march=armv8.5-a+memtag
-endif
 
 #check if the compiler works well
 mte_cc_support := $(shell if ($(CC) $(CFLAGS) -E -x c /dev/null -o /dev/null 2>&1) then echo "1"; fi)
@@ -19,11 +23,14 @@ TEST_GEN_PROGS := $(PROGS)
 
 # Get Kernel headers installed and use them.
 KSFT_KHDR_INSTALL := 1
+else
+    $(warning compiler "$(CC)" does not support the ARMv8.5 MTE extension.)
+    $(warning test program "mte" will not be created.)
 endif
 
 # Include KSFT lib.mk.
 include ../../lib.mk
 
 ifeq ($(mte_cc_support),1)
-$(TEST_GEN_PROGS): mte_common_util.c mte_common_util.h mte_helper.S
+$(TEST_GEN_PROGS): mte_common_util.c mte_helper.S
 endif
diff --git a/tools/testing/selftests/arm64/mte/check_ksm_options.c b/tools/testing/selftests/arm64/mte/check_ksm_options.c
index 3b23c4d61d38..88c74bc46d4f 100644
--- a/tools/testing/selftests/arm64/mte/check_ksm_options.c
+++ b/tools/testing/selftests/arm64/mte/check_ksm_options.c
@@ -33,7 +33,10 @@ static unsigned long read_sysfs(char *str)
 		ksft_print_msg("ERR: missing %s\n", str);
 		return 0;
 	}
-	fscanf(f, "%lu", &val);
+	if (fscanf(f, "%lu", &val) != 1) {
+		ksft_print_msg("ERR: parsing %s\n", str);
+		val = 0;
+	}
 	fclose(f);
 	return val;
 }
diff --git a/tools/testing/selftests/arm64/mte/check_user_mem.c b/tools/testing/selftests/arm64/mte/check_user_mem.c
index 4bfa80f2a8c3..1de7a0abd0ae 100644
--- a/tools/testing/selftests/arm64/mte/check_user_mem.c
+++ b/tools/testing/selftests/arm64/mte/check_user_mem.c
@@ -33,7 +33,8 @@ static int check_usermem_access_fault(int mem_type, int mode, int mapping)
 	if (fd == -1)
 		return KSFT_FAIL;
 	for (i = 0; i < len; i++)
-		write(fd, &val, sizeof(val));
+		if (write(fd, &val, sizeof(val)) != sizeof(val))
+			return KSFT_FAIL;
 	lseek(fd, 0, 0);
 	ptr = mte_allocate_memory(len, mem_type, mapping, true);
 	if (check_allocated_memory(ptr, len, mem_type, true) != KSFT_PASS) {
diff --git a/tools/testing/selftests/arm64/mte/mte_common_util.c b/tools/testing/selftests/arm64/mte/mte_common_util.c
index 39f8908988ea..f50ac31920d1 100644
--- a/tools/testing/selftests/arm64/mte/mte_common_util.c
+++ b/tools/testing/selftests/arm64/mte/mte_common_util.c
@@ -181,10 +181,17 @@ void *mte_allocate_file_memory(size_t size, int mem_type, int mapping, bool tags
 	}
 	/* Initialize the file for mappable size */
 	lseek(fd, 0, SEEK_SET);
-	for (index = INIT_BUFFER_SIZE; index < size; index += INIT_BUFFER_SIZE)
-		write(fd, buffer, INIT_BUFFER_SIZE);
+	for (index = INIT_BUFFER_SIZE; index < size; index += INIT_BUFFER_SIZE) {
+		if (write(fd, buffer, INIT_BUFFER_SIZE) != INIT_BUFFER_SIZE) {
+			perror("initialising buffer");
+			return NULL;
+		}
+	}
 	index -= INIT_BUFFER_SIZE;
-	write(fd, buffer, size - index);
+	if (write(fd, buffer, size - index) != size - index) {
+		perror("initialising buffer");
+		return NULL;
+	}
 	return __mte_allocate_memory_range(size, mem_type, mapping, 0, 0, tags, fd);
 }
 
@@ -202,9 +209,15 @@ void *mte_allocate_file_memory_tag_range(size_t size, int mem_type, int mapping,
 	/* Initialize the file for mappable size */
 	lseek(fd, 0, SEEK_SET);
 	for (index = INIT_BUFFER_SIZE; index < map_size; index += INIT_BUFFER_SIZE)
-		write(fd, buffer, INIT_BUFFER_SIZE);
+		if (write(fd, buffer, INIT_BUFFER_SIZE) != INIT_BUFFER_SIZE) {
+			perror("initialising buffer");
+			return NULL;
+		}
 	index -= INIT_BUFFER_SIZE;
-	write(fd, buffer, map_size - index);
+	if (write(fd, buffer, map_size - index) != map_size - index) {
+		perror("initialising buffer");
+		return NULL;
+	}
 	return __mte_allocate_memory_range(size, mem_type, mapping, range_before,
 					   range_after, true, fd);
 }
@@ -271,29 +284,20 @@ int mte_switch_mode(int mte_option, unsigned long incl_mask)
 
 	en |= (incl_mask << PR_MTE_TAG_SHIFT);
 	/* Enable address tagging ABI, mte error reporting mode and tag inclusion mask. */
-	if (!prctl(PR_SET_TAGGED_ADDR_CTRL, en, 0, 0, 0) == 0) {
+	if (prctl(PR_SET_TAGGED_ADDR_CTRL, en, 0, 0, 0) != 0) {
 		ksft_print_msg("FAIL:prctl PR_SET_TAGGED_ADDR_CTRL for mte mode\n");
 		return -EINVAL;
 	}
 	return 0;
 }
 
-#define ID_AA64PFR1_MTE_SHIFT		8
-#define ID_AA64PFR1_MTE			2
-
 int mte_default_setup(void)
 {
-	unsigned long hwcaps = getauxval(AT_HWCAP);
+	unsigned long hwcaps2 = getauxval(AT_HWCAP2);
 	unsigned long en = 0;
 	int ret;
 
-	if (!(hwcaps & HWCAP_CPUID)) {
-		ksft_print_msg("FAIL: CPUID registers unavailable\n");
-		return KSFT_FAIL;
-	}
-	/* Read ID_AA64PFR1_EL1 register */
-	asm volatile("mrs %0, id_aa64pfr1_el1" : "=r"(hwcaps) : : "memory");
-	if (((hwcaps >> ID_AA64PFR1_MTE_SHIFT) & MT_TAG_MASK) != ID_AA64PFR1_MTE) {
+	if (!(hwcaps2 & HWCAP2_MTE)) {
 		ksft_print_msg("FAIL: MTE features unavailable\n");
 		return KSFT_SKIP;
 	}
@@ -333,6 +337,7 @@ int create_temp_file(void)
 	/* Create a file in the tmpfs filesystem */
 	fd = mkstemp(&filename[0]);
 	if (fd == -1) {
+		perror(filename);
 		ksft_print_msg("FAIL: Unable to open temporary file\n");
 		return 0;
 	}