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 */