This is a note to let you know that I've just added the patch titled
s390: Mark psw in __load_psw_mask() as __unitialized
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-mark-psw-in-__load_psw_mask-as-__unitialized.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c7d1c9caf8204b2224f8f1cabd14f651acc349e2
Author: Sven Schnelle <svens@xxxxxxxxxxxxx>
Date: Tue Apr 30 16:30:01 2024 +0200
s390: Mark psw in __load_psw_mask() as __unitialized
[ Upstream commit 7278a8fb8d032dfdc03d9b5d17e0bc451cdc1492 ]
Without __unitialized, the following code is generated when
INIT_STACK_ALL_ZERO is enabled:
86: d7 0f f0 a0 f0 a0 xc 160(16,%r15), 160(%r15)
8c: e3 40 f0 a0 00 24 stg %r4, 160(%r15)
92: c0 10 00 00 00 08 larl %r1, 0xa2
98: e3 10 f0 a8 00 24 stg %r1, 168(%r15)
9e: b2 b2 f0 a0 lpswe 160(%r15)
The xc is not adding any security because psw is fully initialized
with the following instructions. Add __unitialized to the psw
definitiation to avoid the superfluous clearing of psw.
Reviewed-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Sven Schnelle <svens@xxxxxxxxxxxxx>
Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 48d6ccdef5f77..00bb2d287f740 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -256,8 +256,8 @@ static inline void __load_psw(psw_t psw)
*/
static __always_inline void __load_psw_mask(unsigned long mask)
{
+ psw_t psw __uninitialized;
unsigned long addr;
- psw_t psw;
psw.mask = mask;
