diff options
| author | Heiko Carstens | 2022-05-06 11:33:19 +0200 |
|---|---|---|
| committer | Heiko Carstens | 2022-05-11 14:40:58 +0200 |
| commit | 63678eecec57fc51b778be3da35a397931287170 (patch) | |
| tree | bcb49f8eb4c0824719baec46ce380bbc0e5c8cd6 /arch/s390 | |
| parent | 5ace65ebb5ce9fe1cc8fdbdd97079fb566ef0ea4 (diff) | |
s390/preempt: disable __preempt_count_add() optimization for PROFILE_ALL_BRANCHES
gcc 12 does not (always) optimize away code that should only be generated
if parameters are constant and within in a certain range. This depends on
various obscure kernel config options, however in particular
PROFILE_ALL_BRANCHES can trigger this compile error:
In function ‘__atomic_add_const’,
inlined from ‘__preempt_count_add.part.0’ at ./arch/s390/include/asm/preempt.h:50:3:
./arch/s390/include/asm/atomic_ops.h:80:9: error: impossible constraint in ‘asm’
80 | asm volatile( \
| ^~~
Workaround this by simply disabling the optimization for
PROFILE_ALL_BRANCHES, since the kernel will be so slow, that this
optimization won't matter at all.
Reported-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/include/asm/preempt.h | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/arch/s390/include/asm/preempt.h b/arch/s390/include/asm/preempt.h index d9d5350cc3ec..bf15da0fedbc 100644 --- a/arch/s390/include/asm/preempt.h +++ b/arch/s390/include/asm/preempt.h @@ -46,10 +46,17 @@ static inline bool test_preempt_need_resched(void) static inline void __preempt_count_add(int val) { - if (__builtin_constant_p(val) && (val >= -128) && (val <= 127)) - __atomic_add_const(val, &S390_lowcore.preempt_count); - else - __atomic_add(val, &S390_lowcore.preempt_count); + /* + * With some obscure config options and CONFIG_PROFILE_ALL_BRANCHES + * enabled, gcc 12 fails to handle __builtin_constant_p(). + */ + if (!IS_ENABLED(CONFIG_PROFILE_ALL_BRANCHES)) { + if (__builtin_constant_p(val) && (val >= -128) && (val <= 127)) { + __atomic_add_const(val, &S390_lowcore.preempt_count); + return; + } + } + __atomic_add(val, &S390_lowcore.preempt_count); } static inline void __preempt_count_sub(int val) |