From: Mark Brown <broonie@kernel.org>
Date: Sat, 29 Nov 2025 00:48:45 +0000 (+0000)
Subject: arm64/gcs: Flush the GCS locking state on exec
X-Git-Tag: v6.18.3~70
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5bb88024409ef7bb53e5d42d35097a7a3157f764;p=thirdparty%2Fkernel%2Fstable.git

arm64/gcs: Flush the GCS locking state on exec

commit 98a97bf41528ef738b06eb07ec2b2eb1cfde6ce6 upstream.

When we exec a new task we forget to flush the set of locked GCS mode bits.
Since we do flush the rest of the state this means that if GCS is locked
the new task will be unable to enable GCS, it will be locked as being
disabled. Add the expected flush.

Fixes: fc84bc5378a8 ("arm64/gcs: Context switch GCS state for EL0")
Cc: <stable@vger.kernel.org> # 6.13.x
Reported-by: Yury Khrustalev <Yury.Khrustalev@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Tested-by: Yury Khrustalev <yury.khrustalev@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index fba7ca102a8c4..489554931231e 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -292,6 +292,7 @@ static void flush_gcs(void)
 	current->thread.gcs_base = 0;
 	current->thread.gcs_size = 0;
 	current->thread.gcs_el0_mode = 0;
+	current->thread.gcs_el0_locked = 0;
 	write_sysreg_s(GCSCRE0_EL1_nTR, SYS_GCSCRE0_EL1);
 	write_sysreg_s(0, SYS_GCSPR_EL0);
 }