1/* SPDX-License-Identifier: GPL-2.0 */
  2#ifndef __ASM_PREEMPT_H
  3#define __ASM_PREEMPT_H
  4
  5#include <linux/thread_info.h>
  6
  7#define PREEMPT_ENABLED	(0)
  8
  9static __always_inline int preempt_count(void)
 10{
 11	return READ_ONCE(current_thread_info()->preempt_count);
 12}
 13
 14static __always_inline volatile int *preempt_count_ptr(void)
 15{
 16	return &current_thread_info()->preempt_count;
 17}
 18
 19static __always_inline void preempt_count_set(int pc)
 20{
 21	*preempt_count_ptr() = pc;
 22}
 23
 24/*
 25 * must be macros to avoid header recursion hell
 26 */
 27#define init_task_preempt_count(p) do { \
 28	task_thread_info(p)->preempt_count = FORK_PREEMPT_COUNT; \
 29} while (0)
 30
 31#define init_idle_preempt_count(p, cpu) do { \
 32	task_thread_info(p)->preempt_count = PREEMPT_DISABLED; \
 33} while (0)
 34
 35static __always_inline void set_preempt_need_resched(void)
 36{
 37}
 38
 39static __always_inline void clear_preempt_need_resched(void)
 40{
 41}
 42
 43static __always_inline bool test_preempt_need_resched(void)
 44{
 45	return false;
 46}
 47
 48/*
 49 * The various preempt_count add/sub methods
 50 */
 51
 52static __always_inline void __preempt_count_add(int val)
 53{
 54	*preempt_count_ptr() += val;
 55}
 56
 57static __always_inline void __preempt_count_sub(int val)
 58{
 59	*preempt_count_ptr() -= val;
 60}
 61
 62static __always_inline bool __preempt_count_dec_and_test(void)
 63{
 64	/*
 65	 * Because of load-store architectures cannot do per-cpu atomic
 66	 * operations; we cannot use PREEMPT_NEED_RESCHED because it might get
 67	 * lost.
 68	 */
 69	return !--*preempt_count_ptr() && tif_need_resched();
 70}
 71
 72/*
 73 * Returns true when we need to resched and can (barring IRQ state).
 74 */
 75static __always_inline bool should_resched(int preempt_offset)
 76{
 77	return unlikely(preempt_count() == preempt_offset &&
 78			tif_need_resched());
 79}
 80
 81#ifdef CONFIG_PREEMPTION
 82extern asmlinkage void preempt_schedule(void);
 83extern asmlinkage void preempt_schedule_notrace(void);
 84
 85#if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
 86
 87void dynamic_preempt_schedule(void);
 88void dynamic_preempt_schedule_notrace(void);
 89#define __preempt_schedule()		dynamic_preempt_schedule()
 90#define __preempt_schedule_notrace()	dynamic_preempt_schedule_notrace()
 91
 92#else /* !CONFIG_PREEMPT_DYNAMIC || !CONFIG_HAVE_PREEMPT_DYNAMIC_KEY*/
 93
 94#define __preempt_schedule() preempt_schedule()
 95#define __preempt_schedule_notrace() preempt_schedule_notrace()
 96
 97#endif /* CONFIG_PREEMPT_DYNAMIC && CONFIG_HAVE_PREEMPT_DYNAMIC_KEY*/
 98#endif /* CONFIG_PREEMPTION */
 99
100#endif /* __ASM_PREEMPT_H */