FAILED: patch "[PATCH] s390: Mark psw in __load_psw_mask() as __unitialized" failed to apply to 4.19-stable tree

FAILED: patch "[PATCH] s390: Mark psw in __load_psw_mask() as __unitialized" failed to apply to 4.19-stable tree

[gregkh]

The patch below does not apply to the 4.19-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-4.19.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 '2024071155-mushiness-lumpiness-edc1@gregkh' --subject-prefix 'PATCH 4.19.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;