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63678eecec
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>
140 lines
3.1 KiB
C
140 lines
3.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_PREEMPT_H
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#define __ASM_PREEMPT_H
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#include <asm/current.h>
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#include <linux/thread_info.h>
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#include <asm/atomic_ops.h>
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#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
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/* We use the MSB mostly because its available */
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#define PREEMPT_NEED_RESCHED 0x80000000
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#define PREEMPT_ENABLED (0 + PREEMPT_NEED_RESCHED)
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static inline int preempt_count(void)
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{
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return READ_ONCE(S390_lowcore.preempt_count) & ~PREEMPT_NEED_RESCHED;
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}
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static inline void preempt_count_set(int pc)
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{
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int old, new;
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do {
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old = READ_ONCE(S390_lowcore.preempt_count);
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new = (old & PREEMPT_NEED_RESCHED) |
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(pc & ~PREEMPT_NEED_RESCHED);
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} while (__atomic_cmpxchg(&S390_lowcore.preempt_count,
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old, new) != old);
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}
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static inline void set_preempt_need_resched(void)
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{
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__atomic_and(~PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
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}
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static inline void clear_preempt_need_resched(void)
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{
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__atomic_or(PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
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}
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static inline bool test_preempt_need_resched(void)
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{
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return !(READ_ONCE(S390_lowcore.preempt_count) & PREEMPT_NEED_RESCHED);
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}
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static inline void __preempt_count_add(int val)
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{
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/*
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* With some obscure config options and CONFIG_PROFILE_ALL_BRANCHES
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* enabled, gcc 12 fails to handle __builtin_constant_p().
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*/
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if (!IS_ENABLED(CONFIG_PROFILE_ALL_BRANCHES)) {
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if (__builtin_constant_p(val) && (val >= -128) && (val <= 127)) {
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__atomic_add_const(val, &S390_lowcore.preempt_count);
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return;
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}
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}
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__atomic_add(val, &S390_lowcore.preempt_count);
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}
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static inline void __preempt_count_sub(int val)
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{
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__preempt_count_add(-val);
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}
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static inline bool __preempt_count_dec_and_test(void)
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{
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return __atomic_add(-1, &S390_lowcore.preempt_count) == 1;
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}
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static inline bool should_resched(int preempt_offset)
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{
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return unlikely(READ_ONCE(S390_lowcore.preempt_count) ==
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preempt_offset);
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}
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#else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
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#define PREEMPT_ENABLED (0)
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static inline int preempt_count(void)
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{
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return READ_ONCE(S390_lowcore.preempt_count);
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}
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static inline void preempt_count_set(int pc)
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{
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S390_lowcore.preempt_count = pc;
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}
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static inline void set_preempt_need_resched(void)
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{
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}
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static inline void clear_preempt_need_resched(void)
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{
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}
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static inline bool test_preempt_need_resched(void)
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{
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return false;
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}
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static inline void __preempt_count_add(int val)
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{
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S390_lowcore.preempt_count += val;
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}
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static inline void __preempt_count_sub(int val)
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{
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S390_lowcore.preempt_count -= val;
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}
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static inline bool __preempt_count_dec_and_test(void)
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{
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return !--S390_lowcore.preempt_count && tif_need_resched();
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}
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static inline bool should_resched(int preempt_offset)
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{
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return unlikely(preempt_count() == preempt_offset &&
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tif_need_resched());
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}
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#endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
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#define init_task_preempt_count(p) do { } while (0)
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/* Deferred to CPU bringup time */
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#define init_idle_preempt_count(p, cpu) do { } while (0)
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#ifdef CONFIG_PREEMPTION
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extern void preempt_schedule(void);
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#define __preempt_schedule() preempt_schedule()
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extern void preempt_schedule_notrace(void);
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#define __preempt_schedule_notrace() preempt_schedule_notrace()
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#endif /* CONFIG_PREEMPTION */
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#endif /* __ASM_PREEMPT_H */
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