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
9 static __always_inline int preempt_count(void)
10 {
11 return READ_ONCE(current_thread_info()->preempt_count);
12 }
13
14 static __always_inline volatile int *preempt_count_ptr(void)
15 {
16 return ¤t_thread_info()->preempt_count;
17 }
18
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
35 static __always_inline void set_preempt_need_resched(void)
36 {
37 }
38
39 static __always_inline void clear_preempt_need_resched(void)
40 {
41 }
42
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
52 static __always_inline void __preempt_count_add(int val)
53 {
54 *preempt_count_ptr() += val;
55 }
56
57 static __always_inline void __preempt_count_sub(int val)
58 {
59 *preempt_count_ptr() -= val;
60 }
61
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 */
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
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