[PATCH 1/7] s390/facility: Disable compile time optimization for decompressor code

Heiko Carstens
2024-09-13T13:05:50Z

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>
---
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 b7d234838a36..65ebf86506cd 100644
--- a/arch/s390/include/asm/facility.h
+++ b/arch/s390/include/asm/facility.h
@@ -59,8 +59,10 @@ 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