When setting SME vector lengths we clear TIF_SME to reenable SME traps,
doing a reallocation of the backing storage on next use. We do this using
clear_thread_flag() which operates on the current thread, meaning that when
setting the vector length via ptrace we may both not force traps for the
target task and force a spurious flush of any SME state that the tracing
task may have.
Clear the flag in the target task.
Fixes: e12310a0d30f ("arm64/sme: Implement ptrace support for streaming mode SVE registers")
Reported-by: David Spickett <[email protected]>
Signed-off-by: Mark Brown <[email protected]>
Cc: [email protected]
---
arch/arm64/kernel/fpsimd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 520b681a07bb..a61a1fd6492d 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -909,7 +909,7 @@ int vec_set_vector_length(struct task_struct *task, enum vec_type type,
*/
task->thread.svcr &= ~(SVCR_SM_MASK |
SVCR_ZA_MASK);
- clear_thread_flag(TIF_SME);
+ clear_tsk_thread_flag(task, TIF_SME);
free_sme = true;
}
}
---
base-commit: 5d0c230f1de8c7515b6567d9afba1f196fb4e2f4
change-id: 20230802-arm64-fix-ptrace-tif-sme-0bfd94c8266d
Best regards,
--
Mark Brown <[email protected]>
On Thu, 03 Aug 2023 00:46:39 +0100, Mark Brown wrote:
> When setting SME vector lengths we clear TIF_SME to reenable SME traps,
> doing a reallocation of the backing storage on next use. We do this using
> clear_thread_flag() which operates on the current thread, meaning that when
> setting the vector length via ptrace we may both not force traps for the
> target task and force a spurious flush of any SME state that the tracing
> task may have.
>
> [...]
Applied to arm64 (for-next/fixes), thanks!
[1/1] arm64/fpsimd: Clear SME state in the target task when setting the VL
https://git.kernel.org/arm64/c/c9bb40b7f786
--
Catalin