[PATCH AUTOSEL 6.1 03/42] s390/facility: Disable compile time optimization for decompressor code

Sasha Levin
2024-10-04T18:27:25Z

[ Upstream commit 0147addc4fb72a39448b8873d8acdf3a0f29aa65 ]

Disable compile time optimizations of test_facility() for the
decompressor. The decompressor should not contain any optimized code
depending on the architecture level set the kernel image is compiled
for to avoid unexpected operation exceptions.

Add a __DECOMPRESSOR check to test_facility() to enforce that
facilities are always checked during runtime for the decompressor.

Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/include/asm/facility.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/facility.h b/arch/s390/include/asm/facility.h
index 94b6919026dfb..953d42205ea83 100644
--- a/arch/s390/include/asm/facility.h
+++ b/arch/s390/include/asm/facility.h
@@ -60,8 +60,10 @@ static inline int test_facility(unsigned long nr)
unsigned long facilities_als[] = { FACILITIES_ALS };

if (__builtin_constant_p(nr) && nr < sizeof(facilities_als) * 8) {
- if (__test_facility(nr, &facilities_als))
- return 1;
+ if (__test_facility(nr, &facilities_als)) {
+ if (!__is_defined(__DECOMPRESSOR))
+ return 1;
+ }
}
return __test_facility(nr, &stfle_fac_list);
}
--
2.43.0