[PATCH] alpha: fix PR_GET_UNALIGN flag mask

[PATCH] alpha: fix PR_GET_UNALIGN flag mask

[Magnus Lindholm]

GET_UNALIGN_CTL clears the flags it needs to read, so PR_GET_UNALIGN
always returns zero. Keep the UAC bits when translating them to prctl
flags.

This was uncovered while running the strace test suite on Alpha.

Fixes: 3185bd261882 ("alpha: separate thread-synchronous flags")
Signed-off-by: Magnus Lindholm <linmag7@gmail.com>
---
Tested on UP2000+ (SMP). A standalone regression probe verifies flag
round-trips, EFAULT handling and fork isolation. The probe and unchanged
strace prctl-unalign test fail before the fix and pass afterwards.

 arch/alpha/include/asm/thread_info.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/alpha/include/asm/thread_info.h b/arch/alpha/include/asm/thread_info.h
index d781ac79106d..22c07ce0a77a 100644
--- a/arch/alpha/include/asm/thread_info.h
+++ b/arch/alpha/include/asm/thread_info.h
@@ -110,7 +110,7 @@ register unsigned long *current_stack_pointer __asm__ ("$30");
 	0; })
 
 #define GET_UNALIGN_CTL(task,value)	({				\
-	__u32 status = task_thread_info(task)->status & ~UAC_BITMASK;	\
+	__u32 status = task_thread_info(task)->status & UAC_BITMASK;	\
 	__u32 res = 0;							\
 	if (status & TS_UAC_NOPRINT)					\
 		res |= PR_UNALIGN_NOPRINT;				\

base-commit: 71cf9644bcb35e686c3e12a703325335a0925946
-- 
2.43.0

Re: [PATCH] alpha: fix PR_GET_UNALIGN flag mask

[Matt Turner]

On Sun, Oct 25, 2026 at 08:38:50AM +0100, Magnus Lindholm wrote:
> GET_UNALIGN_CTL clears the flags it needs to read, so PR_GET_UNALIGN
> always returns zero. Keep the UAC bits when translating them to prctl
> flags.
>
> This was uncovered while running the strace test suite on Alpha.
>
> Fixes: 3185bd261882 ("alpha: separate thread-synchronous flags")
> Signed-off-by: Magnus Lindholm <linmag7@gmail.com>

Reviewed-by: Matt Turner <mattst88@gmail.com>

This has been broken since v3.7, so please add

Cc: stable@vger.kernel.org

Re: [PATCH] alpha: fix PR_GET_UNALIGN flag mask

[Magnus Lindholm]

Hi Matt,

On Sun, Oct 25, 2026 at 2:52 PM Matt Turner <mattst88@gmail.com> wrote:
>
> On Sun, Oct 25, 2026 at 08:38:50AM +0100, Magnus Lindholm wrote:
> > GET_UNALIGN_CTL clears the flags it needs to read, so PR_GET_UNALIGN
> > always returns zero. Keep the UAC bits when translating them to prctl
> > flags.
> >
> > This was uncovered while running the strace test suite on Alpha.
> >
> > Fixes: 3185bd261882 ("alpha: separate thread-synchronous flags")
> > Signed-off-by: Magnus Lindholm <linmag7@gmail.com>
>
> Reviewed-by: Matt Turner <mattst88@gmail.com>
>
> This has been broken since v3.7, so please add
>
> Cc: stable@vger.kernel.org

Will do, thanks for the review.

Magnus