* [PATCH 1/2] arm64/signal: Restore TPIDR2 register rather than memory state
2023-06-21 21:00 [PATCH 0/2] arm64/signal: Fix handling of TPIDR2 Mark Brown
@ 2023-06-21 21:00 ` Mark Brown
2023-06-21 21:00 ` [PATCH 2/2] kselftest/arm64: Add a test case for TPIDR2 restore Mark Brown
1 sibling, 0 replies; 4+ messages in thread
From: Mark Brown @ 2023-06-21 21:00 UTC (permalink / raw)
To: Catalin Marinas, Will Deacon, Shuah Khan, Szabolcs Nagy
Cc: linux-arm-kernel, linux-kselftest, Mark Brown, stable
Currently when restoring the TPIDR2 signal context we set the new value
from the signal frame in the thread data structure but not the register,
following the pattern for the rest of the data we are restoring. This does
not work in the case of TPIDR2, the register always has the value for the
current task. This means that either we return to userspace and ignore the
new value or we context switch and save the register value on top of the
newly restored value.
Load the value from the signal context into the register instead.
Fixes: 39e54499280f ("arm64/signal: Include TPIDR2 in the signal context")
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
---
arch/arm64/kernel/signal.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 2cfc810d0a5b..10b407672c42 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -398,7 +398,7 @@ static int restore_tpidr2_context(struct user_ctxs *user)
__get_user_error(tpidr2_el0, &user->tpidr2->tpidr2, err);
if (!err)
- current->thread.tpidr2_el0 = tpidr2_el0;
+ write_sysreg_s(tpidr2_el0, SYS_TPIDR2_EL0);
return err;
}
--
2.30.2
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^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH 2/2] kselftest/arm64: Add a test case for TPIDR2 restore
2023-06-21 21:00 [PATCH 0/2] arm64/signal: Fix handling of TPIDR2 Mark Brown
2023-06-21 21:00 ` [PATCH 1/2] arm64/signal: Restore TPIDR2 register rather than memory state Mark Brown
@ 2023-06-21 21:00 ` Mark Brown
2023-06-22 11:11 ` Mark Brown
1 sibling, 1 reply; 4+ messages in thread
From: Mark Brown @ 2023-06-21 21:00 UTC (permalink / raw)
To: Catalin Marinas, Will Deacon, Shuah Khan, Szabolcs Nagy
Cc: linux-arm-kernel, linux-kselftest, Mark Brown
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>
---
tools/testing/selftests/arm64/signal/.gitignore | 2 +-
.../arm64/signal/testcases/tpidr2_restore.c | 85 ++++++++++++++++++++++
2 files changed, 86 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/arm64/signal/.gitignore b/tools/testing/selftests/arm64/signal/.gitignore
index 8ab4c86837fd..839e3a252629 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 000000000000..c01db4d56eb9
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/tpidr2_restore.c
@@ -0,0 +1,85 @@
+// 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",
+ .timeout = 3,
+ .sig_trig = SIGUSR1,
+ .init = save_tpidr2,
+ .run = modify_tpidr2,
+ .check_result = check_tpidr2,
+};
--
2.30.2
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^ permalink raw reply related [flat|nested] 4+ messages in thread