diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/selftests/arm64/Makefile
index ced910fb4019..1e8d9a8f59df 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 $(ARCH),aarch64 arm64))
-ARM64_SUBTARGETS ?= tags signal pauth fp mte bti
+ARM64_SUBTARGETS ?= tags signal pauth fp mte bti abi
 else
 ARM64_SUBTARGETS :=
 endif
diff --git a/tools/testing/selftests/arm64/abi/.gitignore b/tools/testing/selftests/arm64/abi/.gitignore
new file mode 100644
index 000000000000..4b04670993ea
--- /dev/null
+++ b/tools/testing/selftests/arm64/abi/.gitignore
@@ -0,0 +1 @@
+tpidr2
diff --git a/tools/testing/selftests/arm64/abi/Makefile b/tools/testing/selftests/arm64/abi/Makefile
new file mode 100644
index 000000000000..c32fe00ee67f
--- /dev/null
+++ b/tools/testing/selftests/arm64/abi/Makefile
@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2021 ARM Limited
+
+TEST_GEN_PROGS := tpidr2
+
+include ../../lib.mk
+
+# Build with nolibc since TPIDR2 is intended to be actively managed by
+# libc and we're trying to test the functionality that it depends on here.
+$(OUTPUT)/tpidr2: tpidr2.c
+	$(CC) -fno-asynchronous-unwind-tables -fno-ident -s -Os -nostdlib \
+		-static -include ../../../../include/nolibc/nolibc.h \
+		 -Wall $^ -o $@ -lgcc
diff --git a/tools/testing/selftests/arm64/abi/tpidr2.c b/tools/testing/selftests/arm64/abi/tpidr2.c
new file mode 100644
index 000000000000..351a098b503a
--- /dev/null
+++ b/tools/testing/selftests/arm64/abi/tpidr2.c
@@ -0,0 +1,298 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/sched.h>
+#include <linux/wait.h>
+
+#define SYS_TPIDR2 "S3_3_C13_C0_5"
+
+#define EXPECTED_TESTS 5
+
+static void putstr(const char *str)
+{
+	write(1, str, strlen(str));
+}
+
+static void putnum(unsigned int num)
+{
+	char c;
+
+	if (num / 10)
+		putnum(num / 10);
+
+	c = '0' + (num % 10);
+	write(1, &c, 1);
+}
+
+static int tests_run;
+static int tests_passed;
+static int tests_failed;
+static int tests_skipped;
+
+static void set_tpidr2(uint64_t val)
+{
+	asm volatile (
+		"msr	" SYS_TPIDR2 ", %0\n"
+		:
+		: "r"(val)
+		: "cc");
+}
+
+static uint64_t get_tpidr2(void)
+{
+	uint64_t val;
+
+	asm volatile (
+		"mrs	%0, " SYS_TPIDR2 "\n"
+		: "=r"(val)
+		:
+		: "cc");
+
+	return val;
+}
+
+static void print_summary(void)
+{
+	if (tests_passed + tests_failed + tests_skipped != EXPECTED_TESTS)
+		putstr("# UNEXPECTED TEST COUNT: ");
+
+	putstr("# Totals: pass:");
+	putnum(tests_passed);
+	putstr(" fail:");
+	putnum(tests_failed);
+	putstr(" xfail:0 xpass:0 skip:");
+	putnum(tests_skipped);
+	putstr(" error:0\n");
+}
+
+/* Processes should start with TPIDR2 == 0 */
+static int default_value(void)
+{
+	return get_tpidr2() == 0;
+}
+
+/* If we set TPIDR2 we should read that value */
+static int write_read(void)
+{
+	set_tpidr2(getpid());
+
+	return getpid() == get_tpidr2();
+}
+
+/* If we set a value we should read the same value after scheduling out */
+static int write_sleep_read(void)
+{
+	set_tpidr2(getpid());
+
+	msleep(100);
+
+	return getpid() == get_tpidr2();
+}
+
+/*
+ * If we fork the value in the parent should be unchanged and the
+ * child should start with the same value and be able to set its own
+ * value.
+ */
+static int write_fork_read(void)
+{
+	pid_t newpid, waiting, oldpid;
+	int status;
+
+	set_tpidr2(getpid());
+
+	oldpid = getpid();
+	newpid = fork();
+	if (newpid == 0) {
+		/* In child */
+		if (get_tpidr2() != oldpid) {
+			putstr("# TPIDR2 changed in child: ");
+			putnum(get_tpidr2());
+			putstr("\n");
+			exit(0);
+		}
+
+		set_tpidr2(getpid());
+		if (get_tpidr2() == getpid()) {
+			exit(1);
+		} else {
+			putstr("# Failed to set TPIDR2 in child\n");
+			exit(0);
+		}
+	}
+	if (newpid < 0) {
+		putstr("# fork() failed: -");
+		putnum(-newpid);
+		putstr("\n");
+		return 0;
+	}
+
+	for (;;) {
+		waiting = waitpid(newpid, &status, 0);
+
+		if (waiting < 0) {
+			if (errno == EINTR)
+				continue;
+			putstr("# waitpid() failed: ");
+			putnum(errno);
+			putstr("\n");
+			return 0;
+		}
+		if (waiting != newpid) {
+			putstr("# waitpid() returned wrong PID\n");
+			return 0;
+		}
+
+		if (!WIFEXITED(status)) {
+			putstr("# child did not exit\n");
+			return 0;
+		}
+
+		if (getpid() != get_tpidr2()) {
+			putstr("# TPIDR2 corrupted in parent\n");
+			return 0;
+		}
+
+		return WEXITSTATUS(status);
+	}
+}
+
+/*
+ * sys_clone() has a lot of per architecture variation so just define
+ * it here rather than adding it to nolibc, plus the raw API is a
+ * little more convenient for this test.
+ */
+static int sys_clone(unsigned long clone_flags, unsigned long newsp,
+		     int *parent_tidptr, unsigned long tls,
+		     int *child_tidptr)
+{
+	return my_syscall5(__NR_clone, clone_flags, newsp, parent_tidptr, tls,
+			   child_tidptr);
+}
+
+/*
+ * If we clone with CLONE_SETTLS then the value in the parent should
+ * be unchanged and the child should start with zero and be able to
+ * set its own value.
+ */
+static int write_clone_read(void)
+{
+	int parent_tid, child_tid;
+	pid_t parent, waiting;
+	int ret, status;
+
+	parent = getpid();
+	set_tpidr2(parent);
+
+	ret = sys_clone(CLONE_SETTLS, 0, &parent_tid, 0, &child_tid);
+	if (ret == -1) {
+		putstr("# clone() failed\n");
+		putnum(errno);
+		putstr("\n");
+		return 0;
+	}
+
+	if (ret == 0) {
+		/* In child */
+		if (get_tpidr2() != 0) {
+			putstr("# TPIDR2 non-zero in child: ");
+			putnum(get_tpidr2());
+			putstr("\n");
+			exit(0);
+		}
+
+		if (gettid() == 0)
+			putstr("# Child TID==0\n");
+		set_tpidr2(gettid());
+		if (get_tpidr2() == gettid()) {
+			exit(1);
+		} else {
+			putstr("# Failed to set TPIDR2 in child\n");
+			exit(0);
+		}
+	}
+
+	for (;;) {
+		waiting = wait4(ret, &status, __WCLONE, NULL);
+
+		if (waiting < 0) {
+			if (errno == EINTR)
+				continue;
+			putstr("# wait4() failed: ");
+			putnum(errno);
+			putstr("\n");
+			return 0;
+		}
+		if (waiting != ret) {
+			putstr("# wait4() returned wrong PID ");
+			putnum(waiting);
+			putstr("\n");
+			return 0;
+		}
+
+		if (!WIFEXITED(status)) {
+			putstr("# child did not exit\n");
+			return 0;
+		}
+
+		if (parent != get_tpidr2()) {
+			putstr("# TPIDR2 corrupted in parent\n");
+			return 0;
+		}
+
+		return WEXITSTATUS(status);
+	}
+}
+
+#define run_test(name)			     \
+	if (name()) {			     \
+		tests_passed++;		     \
+	} else {			     \
+		tests_failed++;		     \
+		putstr("not ");		     \
+	}				     \
+	putstr("ok ");			     \
+	putnum(++tests_run);		     \
+	putstr(" " #name "\n");
+
+int main(int argc, char **argv)
+{
+	int ret, i;
+
+	putstr("TAP version 13\n");
+	putstr("1..");
+	putnum(EXPECTED_TESTS);
+	putstr("\n");
+
+	putstr("# PID: ");
+	putnum(getpid());
+	putstr("\n");
+
+	/*
+	 * This test is run with nolibc which doesn't support hwcap and
+	 * it's probably disproportionate to implement so instead check
+	 * for the default vector length configuration in /proc.
+	 */
+	ret = open("/proc/sys/abi/sme_default_vector_length", O_RDONLY, 0);
+	if (ret >= 0) {
+		run_test(default_value);
+		run_test(write_read);
+		run_test(write_sleep_read);
+		run_test(write_fork_read);
+		run_test(write_clone_read);
+
+	} else {
+		putstr("# SME support not present\n");
+
+		for (i = 0; i < EXPECTED_TESTS; i++) {
+			putstr("ok ");
+			putnum(i);
+			putstr(" skipped, TPIDR2 not supported\n");
+		}
+
+		tests_skipped += EXPECTED_TESTS;
+	}
+
+	print_summary();
+
+	return 0;
+}
