This is a note to let you know that I've just added the patch titled
s390/stackleak: Use exrl instead of ex in __stackleak_poison()
to the 6.12-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-stackleak-use-exrl-instead-of-ex-in-__stackleak.patch
and it can be found in the queue-6.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3aa70033399f9a851ddc53be22bdcc41cbd1327d
Author: Sven Schnelle <svens@xxxxxxxxxxxxx>
Date: Wed Jan 8 15:27:02 2025 +0100
s390/stackleak: Use exrl instead of ex in __stackleak_poison()
[ Upstream commit a88c26bb8e04ee5f2678225c0130a5fbc08eef85 ]
exrl is present in all machines currently supported, therefore prefer
it over ex. This saves one instruction and doesn't need an additional
register to hold the address of the target instruction.
Signed-off-by: Sven Schnelle <svens@xxxxxxxxxxxxx>
Reviewed-by: Heiko Carstens <hca@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 9a5236acc0a86..21ae93cbd8e47 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -162,8 +162,7 @@ static __always_inline void __stackleak_poison(unsigned long erase_low,
" la %[addr],256(%[addr])\n"
" brctg %[tmp],0b\n"
"1: stg %[poison],0(%[addr])\n"
- " larl %[tmp],3f\n"
- " ex %[count],0(%[tmp])\n"
+ " exrl %[count],3f\n"
" j 4f\n"
"2: stg %[poison],0(%[addr])\n"
" j 4f\n"
