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  
preempt_count(void)9  static __always_inline int preempt_count(void)
10  {
11  	return READ_ONCE(current_thread_info()->preempt_count);
12  }
13  
preempt_count_ptr(void)14  static __always_inline volatile int *preempt_count_ptr(void)
15  {
16  	return &current_thread_info()->preempt_count;
17  }
18  
preempt_count_set(int pc)19  static __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  
set_preempt_need_resched(void)35  static __always_inline void set_preempt_need_resched(void)
36  {
37  }
38  
clear_preempt_need_resched(void)39  static __always_inline void clear_preempt_need_resched(void)
40  {
41  }
42  
test_preempt_need_resched(void)43  static __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  
__preempt_count_add(int val)52  static __always_inline void __preempt_count_add(int val)
53  {
54  	*preempt_count_ptr() += val;
55  }
56  
__preempt_count_sub(int val)57  static __always_inline void __preempt_count_sub(int val)
58  {
59  	*preempt_count_ptr() -= val;
60  }
61  
__preempt_count_dec_and_test(void)62  static __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   */
should_resched(int preempt_offset)75  static __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
82  extern asmlinkage void preempt_schedule(void);
83  extern asmlinkage void preempt_schedule_notrace(void);
84  
85  #if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
86  
87  void dynamic_preempt_schedule(void);
88  void 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 */
101