linux-kernel - [PATCH RFC 3/3] kselftest/arm64: Add PR_SHADOW_STACK_EXIT

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Message-Id: <20250921-arm64-gcs-exit-token-v1-3-45cf64e648d5@kernel.org>
Date: Sun, 21 Sep 2025 14:21:37 +0100
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>, Christian Brauner <brauner@...nel.org>, 
 Adhemerval Zanella Netto <adhemerval.zanella@...aro.org>, 
 Shuah Khan <shuah@...nel.org>
Cc: Rick Edgecombe <rick.p.edgecombe@...el.com>, 
 Deepak Gupta <debug@...osinc.com>, Wilco Dijkstra <wilco.dijkstra@....com>, 
 Carlos O'Donell <codonell@...hat.com>, Florian Weimer <fweimer@...hat.com>, 
 Szabolcs Nagy <nsz@...t70.net>, Rich Felker <dalias@...c.org>, 
 libc-alpha@...rceware.org, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 Mark Brown <broonie@...nel.org>
Subject: [PATCH RFC 3/3] kselftest/arm64: Add PR_SHADOW_STACK_EXIT_TOKEN to
 gcs-locking

We have added PR_SHADOW_STACK_EXIT_TOKEN, ensure that locking works as
expected for it.

Signed-off-by: Mark Brown <broonie@...nel.org>
---
 tools/testing/selftests/arm64/gcs/gcs-locking.c | 23 +++++++++++++++++++++++
 tools/testing/selftests/arm64/gcs/gcs-util.h    |  3 ++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/arm64/gcs/gcs-locking.c b/tools/testing/selftests/arm64/gcs/gcs-locking.c
index 989f75a491b7..0e8928096918 100644
--- a/tools/testing/selftests/arm64/gcs/gcs-locking.c
+++ b/tools/testing/selftests/arm64/gcs/gcs-locking.c
@@ -77,6 +77,29 @@ FIXTURE_VARIANT_ADD(valid_modes, enable_write_push)
 		PR_SHADOW_STACK_PUSH,
 };
 
+FIXTURE_VARIANT_ADD(valid_modes, enable_token)
+{
+	.mode = PR_SHADOW_STACK_ENABLE | PR_SHADOW_STACK_EXIT_TOKEN,
+};
+
+FIXTURE_VARIANT_ADD(valid_modes, enable_write_exit)
+{
+	.mode = PR_SHADOW_STACK_ENABLE | PR_SHADOW_STACK_WRITE |
+		PR_SHADOW_STACK_EXIT_TOKEN,
+};
+
+FIXTURE_VARIANT_ADD(valid_modes, enable_push_exit)
+{
+	.mode = PR_SHADOW_STACK_ENABLE | PR_SHADOW_STACK_PUSH |
+		PR_SHADOW_STACK_EXIT_TOKEN,
+};
+
+FIXTURE_VARIANT_ADD(valid_modes, enable_write_push_exit)
+{
+	.mode = PR_SHADOW_STACK_ENABLE | PR_SHADOW_STACK_WRITE |
+		PR_SHADOW_STACK_PUSH | PR_SHADOW_STACK_EXIT_TOKEN,
+};
+
 FIXTURE_SETUP(valid_modes)
 {
 }
diff --git a/tools/testing/selftests/arm64/gcs/gcs-util.h b/tools/testing/selftests/arm64/gcs/gcs-util.h
index c99a6b39ac14..1abc9d122ac1 100644
--- a/tools/testing/selftests/arm64/gcs/gcs-util.h
+++ b/tools/testing/selftests/arm64/gcs/gcs-util.h
@@ -36,7 +36,8 @@ struct user_gcs {
 # define PR_SHADOW_STACK_PUSH		(1UL << 2)
 
 #define PR_SHADOW_STACK_ALL_MODES \
-	PR_SHADOW_STACK_ENABLE | PR_SHADOW_STACK_WRITE | PR_SHADOW_STACK_PUSH
+	PR_SHADOW_STACK_ENABLE | PR_SHADOW_STACK_WRITE | \
+	PR_SHADOW_STACK_PUSH | PR_SHADOW_STACK_EXIT_TOKEN
 
 #define SHADOW_STACK_SET_TOKEN (1ULL << 0)     /* Set up a restore token in the shadow stack */
 #define SHADOW_STACK_SET_MARKER (1ULL << 1)     /* Set up a top of stack merker in the shadow stack */

-- 
2.47.2