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
11static inline int preempt_count(void)
12{
13	return READ_ONCE(current_thread_info()->preempt.count);
14}
15
16static 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
30static inline void set_preempt_need_resched(void)
31{
32	current_thread_info()->preempt.need_resched = 0;
33}
34
35static inline void clear_preempt_need_resched(void)
36{
37	current_thread_info()->preempt.need_resched = 1;
38}
39
40static inline bool test_preempt_need_resched(void)
41{
42	return !current_thread_info()->preempt.need_resched;
43}
44
45static 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
52static 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
59static 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
77static 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
85void preempt_schedule(void);
86void preempt_schedule_notrace(void);
87
88#ifdef CONFIG_PREEMPT_DYNAMIC
89
90DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
91void dynamic_preempt_schedule(void);
92#define __preempt_schedule()		dynamic_preempt_schedule()
93void 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