1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __ASM_PREEMPT_H
3 #define __ASM_PREEMPT_H
5 #include <asm/current.h>
6 #include <linux/thread_info.h>
7 #include <asm/atomic_ops.h>
9 #ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
11 /* We use the MSB mostly because its available */
12 #define PREEMPT_NEED_RESCHED 0x80000000
13 #define PREEMPT_ENABLED (0 + PREEMPT_NEED_RESCHED)
15 static inline int preempt_count(void)
17 return READ_ONCE(S390_lowcore.preempt_count) & ~PREEMPT_NEED_RESCHED;
20 static inline void preempt_count_set(int pc)
25 old = READ_ONCE(S390_lowcore.preempt_count);
26 new = (old & PREEMPT_NEED_RESCHED) |
27 (pc & ~PREEMPT_NEED_RESCHED);
28 } while (__atomic_cmpxchg(&S390_lowcore.preempt_count,
32 static inline void set_preempt_need_resched(void)
34 __atomic_and(~PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
37 static inline void clear_preempt_need_resched(void)
39 __atomic_or(PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
42 static inline bool test_preempt_need_resched(void)
44 return !(READ_ONCE(S390_lowcore.preempt_count) & PREEMPT_NEED_RESCHED);
47 static inline void __preempt_count_add(int val)
49 if (__builtin_constant_p(val) && (val >= -128) && (val <= 127))
50 __atomic_add_const(val, &S390_lowcore.preempt_count);
52 __atomic_add(val, &S390_lowcore.preempt_count);
55 static inline void __preempt_count_sub(int val)
57 __preempt_count_add(-val);
60 static inline bool __preempt_count_dec_and_test(void)
62 return __atomic_add(-1, &S390_lowcore.preempt_count) == 1;
65 static inline bool should_resched(int preempt_offset)
67 return unlikely(READ_ONCE(S390_lowcore.preempt_count) ==
71 #else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
73 #define PREEMPT_ENABLED (0)
75 static inline int preempt_count(void)
77 return READ_ONCE(S390_lowcore.preempt_count);
80 static inline void preempt_count_set(int pc)
82 S390_lowcore.preempt_count = pc;
85 static inline void set_preempt_need_resched(void)
89 static inline void clear_preempt_need_resched(void)
93 static inline bool test_preempt_need_resched(void)
98 static inline void __preempt_count_add(int val)
100 S390_lowcore.preempt_count += val;
103 static inline void __preempt_count_sub(int val)
105 S390_lowcore.preempt_count -= val;
108 static inline bool __preempt_count_dec_and_test(void)
110 return !--S390_lowcore.preempt_count && tif_need_resched();
113 static inline bool should_resched(int preempt_offset)
115 return unlikely(preempt_count() == preempt_offset &&
119 #endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
121 #define init_task_preempt_count(p) do { } while (0)
122 /* Deferred to CPU bringup time */
123 #define init_idle_preempt_count(p, cpu) do { } while (0)
125 #ifdef CONFIG_PREEMPTION
126 extern void preempt_schedule(void);
127 #define __preempt_schedule() preempt_schedule()
128 extern void preempt_schedule_notrace(void);
129 #define __preempt_schedule_notrace() preempt_schedule_notrace()
130 #endif /* CONFIG_PREEMPTION */
132 #endif /* __ASM_PREEMPT_H */