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_ENABLED; \
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_PREEMPT
82 extern asmlinkage void preempt_schedule(void);
83 #define __preempt_schedule() preempt_schedule()
84 extern asmlinkage void preempt_schedule_notrace(void);
85 #define __preempt_schedule_notrace() preempt_schedule_notrace()
86 #endif /* CONFIG_PREEMPT */
87 
88 #endif /* __ASM_PREEMPT_H */
89