1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __ASM_PREEMPT_H
3 #define __ASM_PREEMPT_H
4
5 #include <asm/current.h>
6 #include <linux/thread_info.h>
7 #include <asm/atomic_ops.h>
8
9 #ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
10
11 /* We use the MSB mostly because its available */
12 #define PREEMPT_NEED_RESCHED 0x80000000
13 #define PREEMPT_ENABLED (0 + PREEMPT_NEED_RESCHED)
14
preempt_count(void)15 static inline int preempt_count(void)
16 {
17 return READ_ONCE(S390_lowcore.preempt_count) & ~PREEMPT_NEED_RESCHED;
18 }
19
preempt_count_set(int pc)20 static inline void preempt_count_set(int pc)
21 {
22 int old, new;
23
24 do {
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,
29 old, new) != old);
30 }
31
32 #define init_task_preempt_count(p) do { } while (0)
33
34 #define init_idle_preempt_count(p, cpu) do { \
35 S390_lowcore.preempt_count = PREEMPT_ENABLED; \
36 } while (0)
37
set_preempt_need_resched(void)38 static inline void set_preempt_need_resched(void)
39 {
40 __atomic_and(~PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
41 }
42
clear_preempt_need_resched(void)43 static inline void clear_preempt_need_resched(void)
44 {
45 __atomic_or(PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
46 }
47
test_preempt_need_resched(void)48 static inline bool test_preempt_need_resched(void)
49 {
50 return !(READ_ONCE(S390_lowcore.preempt_count) & PREEMPT_NEED_RESCHED);
51 }
52
__preempt_count_add(int val)53 static inline void __preempt_count_add(int val)
54 {
55 if (__builtin_constant_p(val) && (val >= -128) && (val <= 127))
56 __atomic_add_const(val, &S390_lowcore.preempt_count);
57 else
58 __atomic_add(val, &S390_lowcore.preempt_count);
59 }
60
__preempt_count_sub(int val)61 static inline void __preempt_count_sub(int val)
62 {
63 __preempt_count_add(-val);
64 }
65
__preempt_count_dec_and_test(void)66 static inline bool __preempt_count_dec_and_test(void)
67 {
68 return __atomic_add(-1, &S390_lowcore.preempt_count) == 1;
69 }
70
should_resched(int preempt_offset)71 static inline bool should_resched(int preempt_offset)
72 {
73 return unlikely(READ_ONCE(S390_lowcore.preempt_count) ==
74 preempt_offset);
75 }
76
77 #else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
78
79 #define PREEMPT_ENABLED (0)
80
preempt_count(void)81 static inline int preempt_count(void)
82 {
83 return READ_ONCE(S390_lowcore.preempt_count);
84 }
85
preempt_count_set(int pc)86 static inline void preempt_count_set(int pc)
87 {
88 S390_lowcore.preempt_count = pc;
89 }
90
91 #define init_task_preempt_count(p) do { } while (0)
92
93 #define init_idle_preempt_count(p, cpu) do { \
94 S390_lowcore.preempt_count = PREEMPT_ENABLED; \
95 } while (0)
96
set_preempt_need_resched(void)97 static inline void set_preempt_need_resched(void)
98 {
99 }
100
clear_preempt_need_resched(void)101 static inline void clear_preempt_need_resched(void)
102 {
103 }
104
test_preempt_need_resched(void)105 static inline bool test_preempt_need_resched(void)
106 {
107 return false;
108 }
109
__preempt_count_add(int val)110 static inline void __preempt_count_add(int val)
111 {
112 S390_lowcore.preempt_count += val;
113 }
114
__preempt_count_sub(int val)115 static inline void __preempt_count_sub(int val)
116 {
117 S390_lowcore.preempt_count -= val;
118 }
119
__preempt_count_dec_and_test(void)120 static inline bool __preempt_count_dec_and_test(void)
121 {
122 return !--S390_lowcore.preempt_count && tif_need_resched();
123 }
124
should_resched(int preempt_offset)125 static inline bool should_resched(int preempt_offset)
126 {
127 return unlikely(preempt_count() == preempt_offset &&
128 tif_need_resched());
129 }
130
131 #endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
132
133 #ifdef CONFIG_PREEMPT
134 extern asmlinkage void preempt_schedule(void);
135 #define __preempt_schedule() preempt_schedule()
136 extern asmlinkage void preempt_schedule_notrace(void);
137 #define __preempt_schedule_notrace() preempt_schedule_notrace()
138 #endif /* CONFIG_PREEMPT */
139
140 #endif /* __ASM_PREEMPT_H */
141