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s390: Mark psw in __load_psw_mask() as __unitialized

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[ 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@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Sven Schnelle 2024-04-30 16:30:01 +02:00 committed by Greg Kroah-Hartman
parent 7a67c4e476
commit 834681e42a
1 changed files with 1 additions and 1 deletions
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2
arch/s390/include/asm/processor.h
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@ -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;