1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __ASM_PREEMPT_H
3 #define __ASM_PREEMPT_H
4
5 #include <linux/jump_label.h>
6 #include <linux/thread_info.h>
7
8 #define PREEMPT_NEED_RESCHED BIT(32)
9 #define PREEMPT_ENABLED (PREEMPT_NEED_RESCHED)
10
11 static inline int preempt_count(void)
12 {
13 return READ_ONCE(current_thread_info()->preempt.count);
14 }
15
16 static inline void preempt_count_set(u64 pc)
17 {
18 /* Preserve existing value of PREEMPT_NEED_RESCHED */
19 WRITE_ONCE(current_thread_info()->preempt.count, pc);
20 }
21
22 #define init_task_preempt_count(p) do { \
23 task_thread_info(p)->preempt_count = FORK_PREEMPT_COUNT; \
24 } while (0)
25
26 #define init_idle_preempt_count(p, cpu) do { \
27 task_thread_info(p)->preempt_count = PREEMPT_DISABLED; \
28 } while (0)
29
30 static inline void set_preempt_need_resched(void)
31 {
32 current_thread_info()->preempt.need_resched = 0;
33 }
34
35 static inline void clear_preempt_need_resched(void)
36 {
37 current_thread_info()->preempt.need_resched = 1;
38 }
39
40 static inline bool test_preempt_need_resched(void)
41 {
42 return !current_thread_info()->preempt.need_resched;
43 }
44
45 static inline void __preempt_count_add(int val)
46 {
47 u32 pc = READ_ONCE(current_thread_info()->preempt.count);
48 pc += val;
49 WRITE_ONCE(current_thread_info()->preempt.count, pc);
50 }
51
52 static inline void __preempt_count_sub(int val)
53 {
54 u32 pc = READ_ONCE(current_thread_info()->preempt.count);
55 pc -= val;
56 WRITE_ONCE(current_thread_info()->preempt.count, pc);
57 }
58
59 static inline bool __preempt_count_dec_and_test(void)
60 {
61 struct thread_info *ti = current_thread_info();
62 u64 pc = READ_ONCE(ti->preempt_count);
63
64 /* Update only the count field, leaving need_resched unchanged */
65 WRITE_ONCE(ti->preempt.count, --pc);
66
67 /*
68 * If we wrote back all zeroes, then we're preemptible and in
69 * need of a reschedule. Otherwise, we need to reload the
70 * preempt_count in case the need_resched flag was cleared by an
71 * interrupt occurring between the non-atomic READ_ONCE/WRITE_ONCE
72 * pair.
73 */
74 return !pc || !READ_ONCE(ti->preempt_count);
75 }
76
77 static inline bool should_resched(int preempt_offset)
78 {
79 u64 pc = READ_ONCE(current_thread_info()->preempt_count);
80 return pc == preempt_offset;
81 }
82
83 #ifdef CONFIG_PREEMPTION
84
85 void preempt_schedule(void);
86 void preempt_schedule_notrace(void);
87
88 #ifdef CONFIG_PREEMPT_DYNAMIC
89
90 DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
91 void dynamic_preempt_schedule(void);
92 #define __preempt_schedule() dynamic_preempt_schedule()
93 void dynamic_preempt_schedule_notrace(void);
94 #define __preempt_schedule_notrace() dynamic_preempt_schedule_notrace()
95
96 #else /* CONFIG_PREEMPT_DYNAMIC */
97
98 #define __preempt_schedule() preempt_schedule()
99 #define __preempt_schedule_notrace() preempt_schedule_notrace()
100
101 #endif /* CONFIG_PREEMPT_DYNAMIC */
102 #endif /* CONFIG_PREEMPTION */
103
104 #endif /* __ASM_PREEMPT_H */
105
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