* [PATCH AUTOSEL 6.13 4/7] s390/stackleak: Use exrl instead of ex in __stackleak_poison()
[not found] <20250126144839.925271-1-sashal@kernel.org>
@ 2025-01-26 14:48 ` Sasha Levin
0 siblings, 0 replies; only message in thread
From: Sasha Levin @ 2025-01-26 14:48 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Sven Schnelle, Heiko Carstens, Alexander Gordeev, Sasha Levin,
gor, imbrenda, meted, linux-s390
From: Sven Schnelle <svens@linux.ibm.com>
[ 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@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/include/asm/processor.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 8761fd01a9f09..4f8d5592c2981 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -163,8 +163,7 @@ 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"
--
2.39.5
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