The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 7278a8fb8d032dfdc03d9b5d17e0bc451cdc1492 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024071154-kitten-oxidize-b3a1@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

7278a8fb8d03 ("s390: Mark psw in __load_psw_mask() as __unitialized")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7278a8fb8d032dfdc03d9b5d17e0bc451cdc1492 Mon Sep 17 00:00:00 2001 From: Sven Schnelle svens@linux.ibm.com Date: Tue, 30 Apr 2024 16:30:01 +0200 Subject: [PATCH] s390: Mark psw in __load_psw_mask() as __unitialized

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@linux.ibm.com Signed-off-by: Sven Schnelle svens@linux.ibm.com Signed-off-by: Alexander Gordeev agordeev@linux.ibm.com

diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h index 1e2fc6d6963c..07ad5a1df878 100644 --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -314,8 +314,8 @@ 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;