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Peter Zijlstrac2daa3b2013-08-14 14:51:00 +02001#ifndef __ASM_PREEMPT_H
2#define __ASM_PREEMPT_H
3
4#include <asm/rmwcc.h>
5#include <asm/percpu.h>
6#include <linux/thread_info.h>
7
8DECLARE_PER_CPU(int, __preempt_count);
9
10/*
Peter Zijlstraba1f14f2013-11-28 14:26:41 +010011 * We use the PREEMPT_NEED_RESCHED bit as an inverted NEED_RESCHED such
12 * that a decrement hitting 0 means we can and should reschedule.
13 */
14#define PREEMPT_ENABLED (0 + PREEMPT_NEED_RESCHED)
15
16/*
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020017 * We mask the PREEMPT_NEED_RESCHED bit so as not to confuse all current users
18 * that think a non-zero value indicates we cannot preempt.
19 */
20static __always_inline int preempt_count(void)
21{
Christoph Lameterb3ca1c12014-04-07 15:39:34 -070022 return raw_cpu_read_4(__preempt_count) & ~PREEMPT_NEED_RESCHED;
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020023}
24
25static __always_inline void preempt_count_set(int pc)
26{
Christoph Lameterb3ca1c12014-04-07 15:39:34 -070027 raw_cpu_write_4(__preempt_count, pc);
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020028}
29
30/*
31 * must be macros to avoid header recursion hell
32 */
Peter Zijlstrad87b7a32015-09-28 18:11:18 +020033#define init_task_preempt_count(p) do { } while (0)
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020034
35#define init_idle_preempt_count(p, cpu) do { \
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020036 per_cpu(__preempt_count, (cpu)) = PREEMPT_ENABLED; \
37} while (0)
38
39/*
40 * We fold the NEED_RESCHED bit into the preempt count such that
41 * preempt_enable() can decrement and test for needing to reschedule with a
42 * single instruction.
43 *
44 * We invert the actual bit, so that when the decrement hits 0 we know we both
45 * need to resched (the bit is cleared) and can resched (no preempt count).
46 */
47
48static __always_inline void set_preempt_need_resched(void)
49{
Christoph Lameterb3ca1c12014-04-07 15:39:34 -070050 raw_cpu_and_4(__preempt_count, ~PREEMPT_NEED_RESCHED);
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020051}
52
53static __always_inline void clear_preempt_need_resched(void)
54{
Christoph Lameterb3ca1c12014-04-07 15:39:34 -070055 raw_cpu_or_4(__preempt_count, PREEMPT_NEED_RESCHED);
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020056}
57
58static __always_inline bool test_preempt_need_resched(void)
59{
Christoph Lameterb3ca1c12014-04-07 15:39:34 -070060 return !(raw_cpu_read_4(__preempt_count) & PREEMPT_NEED_RESCHED);
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020061}
62
63/*
64 * The various preempt_count add/sub methods
65 */
66
67static __always_inline void __preempt_count_add(int val)
68{
Christoph Lameterb3ca1c12014-04-07 15:39:34 -070069 raw_cpu_add_4(__preempt_count, val);
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020070}
71
72static __always_inline void __preempt_count_sub(int val)
73{
Christoph Lameterb3ca1c12014-04-07 15:39:34 -070074 raw_cpu_add_4(__preempt_count, -val);
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020075}
76
Peter Zijlstraba1f14f2013-11-28 14:26:41 +010077/*
78 * Because we keep PREEMPT_NEED_RESCHED set when we do _not_ need to reschedule
79 * a decrement which hits zero means we have no preempt_count and should
80 * reschedule.
81 */
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020082static __always_inline bool __preempt_count_dec_and_test(void)
83{
H. Peter Anvin18fe5822016-06-08 12:38:39 -070084 GEN_UNARY_RMWcc("decl", __preempt_count, __percpu_arg(0), e);
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020085}
86
87/*
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020088 * Returns true when we need to resched and can (barring IRQ state).
89 */
Konstantin Khlebnikovfe32d3c2015-07-15 12:52:04 +030090static __always_inline bool should_resched(int preempt_offset)
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020091{
Konstantin Khlebnikovfe32d3c2015-07-15 12:52:04 +030092 return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset);
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +020093}
94
Peter Zijlstra1a338ac2013-08-14 14:51:00 +020095#ifdef CONFIG_PREEMPT
96 extern asmlinkage void ___preempt_schedule(void);
Josh Poimboeuf821eae72016-02-18 11:41:58 -060097# define __preempt_schedule() \
98({ \
99 register void *__sp asm(_ASM_SP); \
100 asm volatile ("call ___preempt_schedule" : "+r"(__sp)); \
101})
102
Peter Zijlstra1a338ac2013-08-14 14:51:00 +0200103 extern asmlinkage void preempt_schedule(void);
Frederic Weisbecker4eaca0a2015-06-04 17:39:08 +0200104 extern asmlinkage void ___preempt_schedule_notrace(void);
Josh Poimboeuf821eae72016-02-18 11:41:58 -0600105# define __preempt_schedule_notrace() \
106({ \
107 register void *__sp asm(_ASM_SP); \
108 asm volatile ("call ___preempt_schedule_notrace" : "+r"(__sp)); \
109})
Frederic Weisbecker4eaca0a2015-06-04 17:39:08 +0200110 extern asmlinkage void preempt_schedule_notrace(void);
Peter Zijlstra1a338ac2013-08-14 14:51:00 +0200111#endif
112
Peter Zijlstrac2daa3b2013-08-14 14:51:00 +0200113#endif /* __ASM_PREEMPT_H */