From: Heiko Carstens Date: Fri, 6 May 2022 09:33:19 +0000 (+0200) Subject: s390/preempt: disable __preempt_count_add() optimization for PROFILE_ALL_BRANCHES X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=30cf47a602746a9a5e37834193885824c7a28f2e;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git s390/preempt: disable __preempt_count_add() optimization for PROFILE_ALL_BRANCHES [ Upstream commit 63678eecec57fc51b778be3da35a397931287170 ] 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 Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin --- diff --git a/arch/s390/include/asm/preempt.h b/arch/s390/include/asm/preempt.h index 23a14d187fb1..1aebf09fbcd8 100644 --- a/arch/s390/include/asm/preempt.h +++ b/arch/s390/include/asm/preempt.h @@ -50,10 +50,17 @@ 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)