From f7a5d72edc522b9210521d9b3969eac221eb6ecb Mon Sep 17 00:00:00 2001
From: Mark Brown <broonie@kernel.org>
Date: Thu, 22 Jun 2023 14:39:46 +0100
Subject: [PATCH] kselftest/arm64: Add a test case for TPIDR2 restore

Due to the fact that TPIDR2 is intended to be managed by libc we don't
currently test modifying it via the signal context since that might
disrupt libc's usage of it and cause instability. We can however test the
opposite case with less risk, modifying TPIDR2 in a signal handler and
making sure that the original value is restored after returning from the
signal handler. Add a test which does this.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230621-arm64-fix-tpidr2-signal-restore-v2-2-c8e8fcc10302@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
 tools/testing/selftests/arm64/signal/.gitignore    |  2 +-
 .../arm64/signal/testcases/tpidr2_restore.c        | 86 ++++++++++++++++++++++
 2 files changed, 87 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/arm64/signal/testcases/tpidr2_restore.c

diff --git a/tools/testing/selftests/arm64/signal/.gitignore b/tools/testing/selftests/arm64/signal/.gitignore
index 8ab4c86..839e3a2 100644
--- a/tools/testing/selftests/arm64/signal/.gitignore
+++ b/tools/testing/selftests/arm64/signal/.gitignore
@@ -4,7 +4,7 @@ fake_sigreturn_*
 sme_*
 ssve_*
 sve_*
-tpidr2_siginfo
+tpidr2_*
 za_*
 zt_*
 !*.[ch]
diff --git a/tools/testing/selftests/arm64/signal/testcases/tpidr2_restore.c b/tools/testing/selftests/arm64/signal/testcases/tpidr2_restore.c
new file mode 100644
index 0000000..f9a86c0
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/tpidr2_restore.c
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 ARM Limited
+ *
+ * Verify that the TPIDR2 register context in signal frames is restored.
+ */
+
+#include <signal.h>
+#include <ucontext.h>
+#include <sys/auxv.h>
+#include <sys/prctl.h>
+#include <unistd.h>
+#include <asm/sigcontext.h>
+
+#include "test_signals_utils.h"
+#include "testcases.h"
+
+#define SYS_TPIDR2 "S3_3_C13_C0_5"
+
+static uint64_t get_tpidr2(void)
+{
+	uint64_t val;
+
+	asm volatile (
+		"mrs	%0, " SYS_TPIDR2 "\n"
+		: "=r"(val)
+		:
+		: "cc");
+
+	return val;
+}
+
+static void set_tpidr2(uint64_t val)
+{
+	asm volatile (
+		"msr	" SYS_TPIDR2 ", %0\n"
+		:
+		: "r"(val)
+		: "cc");
+}
+
+
+static uint64_t initial_tpidr2;
+
+static bool save_tpidr2(struct tdescr *td)
+{
+	initial_tpidr2 = get_tpidr2();
+	fprintf(stderr, "Initial TPIDR2: %lx\n", initial_tpidr2);
+
+	return true;
+}
+
+static int modify_tpidr2(struct tdescr *td, siginfo_t *si, ucontext_t *uc)
+{
+	uint64_t my_tpidr2 = get_tpidr2();
+
+	my_tpidr2++;
+	fprintf(stderr, "Setting TPIDR2 to %lx\n", my_tpidr2);
+	set_tpidr2(my_tpidr2);
+
+	return 0;
+}
+
+static void check_tpidr2(struct tdescr *td)
+{
+	uint64_t tpidr2 = get_tpidr2();
+
+	td->pass = tpidr2 == initial_tpidr2;
+
+	if (td->pass)
+		fprintf(stderr, "TPIDR2 restored\n");
+	else
+		fprintf(stderr, "TPIDR2 was %lx but is now %lx\n",
+			initial_tpidr2, tpidr2);
+}
+
+struct tdescr tde = {
+	.name = "TPIDR2 restore",
+	.descr = "Validate that TPIDR2 is restored from the sigframe",
+	.feats_required = FEAT_SME,
+	.timeout = 3,
+	.sig_trig = SIGUSR1,
+	.init = save_tpidr2,
+	.run = modify_tpidr2,
+	.check_result = check_tpidr2,
+};
-- 
2.7.4