* [PATCH] arm64: process: Fix context switching MTE store-only tag check
@ 2026-08-19 14:48 Vladimir Murzin
2026-08-19 15:24 ` Yeoreum Yun
2026-08-19 15:44 ` Catalin Marinas
0 siblings, 2 replies; 3+ messages in thread
From: Vladimir Murzin @ 2026-08-19 14:48 UTC (permalink / raw)
To: linux-arm-kernel; +Cc: catalin.marinas, will, yeoreum.yun
SCTLR_EL1.TCSO0 is set when user opt-in for MTE store-only tag check
mode. However, it is not part of SCTLR_USER_MASK which imply that on
context switch we never clear SCTLR_EL1.TCSO0, so we are leaking that
setting into another task.
Fix that by including SCTLR_EL1_TCSO0_MASK into SCTLR_USER_MASK
Fixes: 4d51ff5bba00 ("arm64/kernel: Support store-only mte tag check")
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
arch/arm64/include/asm/processor.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index c2a627f39314..6dfbcacd9ba0 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -264,7 +264,7 @@ static inline void task_set_sve_vl_onexec(struct task_struct *task,
#define SCTLR_USER_MASK \
(SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | SCTLR_ELx_ENDA | SCTLR_ELx_ENDB | \
- SCTLR_EL1_TCF0_MASK)
+ SCTLR_EL1_TCF0_MASK | SCTLR_EL1_TCSO0_MASK)
static inline void arch_thread_struct_whitelist(unsigned long *offset,
unsigned long *size)
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] arm64: process: Fix context switching MTE store-only tag check
2026-08-19 14:48 [PATCH] arm64: process: Fix context switching MTE store-only tag check Vladimir Murzin
@ 2026-08-19 15:24 ` Yeoreum Yun
2026-08-19 15:44 ` Catalin Marinas
1 sibling, 0 replies; 3+ messages in thread
From: Yeoreum Yun @ 2026-08-19 15:24 UTC (permalink / raw)
To: Vladimir Murzin; +Cc: linux-arm-kernel, catalin.marinas, will, yeoreum.yun
> SCTLR_EL1.TCSO0 is set when user opt-in for MTE store-only tag check
> mode. However, it is not part of SCTLR_USER_MASK which imply that on
> context switch we never clear SCTLR_EL1.TCSO0, so we are leaking that
> setting into another task.
> Fix that by including SCTLR_EL1_TCSO0_MASK into SCTLR_USER_MASK
>
> Fixes: 4d51ff5bba00 ("arm64/kernel: Support store-only mte tag check")
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> ---
> arch/arm64/include/asm/processor.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
> index c2a627f39314..6dfbcacd9ba0 100644
> --- a/arch/arm64/include/asm/processor.h
> +++ b/arch/arm64/include/asm/processor.h
> @@ -264,7 +264,7 @@ static inline void task_set_sve_vl_onexec(struct task_struct *task,
>
> #define SCTLR_USER_MASK \
> (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | SCTLR_ELx_ENDA | SCTLR_ELx_ENDB | \
> - SCTLR_EL1_TCF0_MASK)
> + SCTLR_EL1_TCF0_MASK | SCTLR_EL1_TCSO0_MASK)
>
> static inline void arch_thread_struct_whitelist(unsigned long *offset,
> unsigned long *size)
> --
> 2.34.1
Oops, Sorry for this.
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
--
Sincerely,
Yeoreum Yun
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] arm64: process: Fix context switching MTE store-only tag check
2026-08-19 14:48 [PATCH] arm64: process: Fix context switching MTE store-only tag check Vladimir Murzin
2026-08-19 15:24 ` Yeoreum Yun
@ 2026-08-19 15:44 ` Catalin Marinas
1 sibling, 0 replies; 3+ messages in thread
From: Catalin Marinas @ 2026-08-19 15:44 UTC (permalink / raw)
To: Vladimir Murzin; +Cc: linux-arm-kernel, will, yeoreum.yun
On Wed, Aug 19, 2026 at 03:48:59PM +0100, Vladimir Murzin wrote:
> SCTLR_EL1.TCSO0 is set when user opt-in for MTE store-only tag check
> mode. However, it is not part of SCTLR_USER_MASK which imply that on
> context switch we never clear SCTLR_EL1.TCSO0, so we are leaking that
> setting into another task.
>
> Fix that by including SCTLR_EL1_TCSO0_MASK into SCTLR_USER_MASK
>
> Fixes: 4d51ff5bba00 ("arm64/kernel: Support store-only mte tag check")
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-08-19 14:48 [PATCH] arm64: process: Fix context switching MTE store-only tag check Vladimir Murzin
2026-08-19 15:24 ` Yeoreum Yun
2026-08-19 15:44 ` Catalin Marinas
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