Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost
[cris-mirror.git] / arch / x86 / include / asm / preempt.h
blob7f2dbd91fc743a516a0ad8e094680b13832f61ef
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __ASM_PREEMPT_H
3 #define __ASM_PREEMPT_H
5 #include <asm/rmwcc.h>
6 #include <asm/percpu.h>
7 #include <linux/thread_info.h>
9 DECLARE_PER_CPU(int, __preempt_count);
12 * We use the PREEMPT_NEED_RESCHED bit as an inverted NEED_RESCHED such
13 * that a decrement hitting 0 means we can and should reschedule.
15 #define PREEMPT_ENABLED (0 + PREEMPT_NEED_RESCHED)
18 * We mask the PREEMPT_NEED_RESCHED bit so as not to confuse all current users
19 * that think a non-zero value indicates we cannot preempt.
21 static __always_inline int preempt_count(void)
23 return raw_cpu_read_4(__preempt_count) & ~PREEMPT_NEED_RESCHED;
26 static __always_inline void preempt_count_set(int pc)
28 int old, new;
30 do {
31 old = raw_cpu_read_4(__preempt_count);
32 new = (old & PREEMPT_NEED_RESCHED) |
33 (pc & ~PREEMPT_NEED_RESCHED);
34 } while (raw_cpu_cmpxchg_4(__preempt_count, old, new) != old);
38 * must be macros to avoid header recursion hell
40 #define init_task_preempt_count(p) do { } while (0)
42 #define init_idle_preempt_count(p, cpu) do { \
43 per_cpu(__preempt_count, (cpu)) = PREEMPT_ENABLED; \
44 } while (0)
47 * We fold the NEED_RESCHED bit into the preempt count such that
48 * preempt_enable() can decrement and test for needing to reschedule with a
49 * single instruction.
51 * We invert the actual bit, so that when the decrement hits 0 we know we both
52 * need to resched (the bit is cleared) and can resched (no preempt count).
55 static __always_inline void set_preempt_need_resched(void)
57 raw_cpu_and_4(__preempt_count, ~PREEMPT_NEED_RESCHED);
60 static __always_inline void clear_preempt_need_resched(void)
62 raw_cpu_or_4(__preempt_count, PREEMPT_NEED_RESCHED);
65 static __always_inline bool test_preempt_need_resched(void)
67 return !(raw_cpu_read_4(__preempt_count) & PREEMPT_NEED_RESCHED);
71 * The various preempt_count add/sub methods
74 static __always_inline void __preempt_count_add(int val)
76 raw_cpu_add_4(__preempt_count, val);
79 static __always_inline void __preempt_count_sub(int val)
81 raw_cpu_add_4(__preempt_count, -val);
85 * Because we keep PREEMPT_NEED_RESCHED set when we do _not_ need to reschedule
86 * a decrement which hits zero means we have no preempt_count and should
87 * reschedule.
89 static __always_inline bool __preempt_count_dec_and_test(void)
91 GEN_UNARY_RMWcc("decl", __preempt_count, __percpu_arg(0), e);
95 * Returns true when we need to resched and can (barring IRQ state).
97 static __always_inline bool should_resched(int preempt_offset)
99 return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset);
102 #ifdef CONFIG_PREEMPT
103 extern asmlinkage void ___preempt_schedule(void);
104 # define __preempt_schedule() \
105 asm volatile ("call ___preempt_schedule" : ASM_CALL_CONSTRAINT)
107 extern asmlinkage void preempt_schedule(void);
108 extern asmlinkage void ___preempt_schedule_notrace(void);
109 # define __preempt_schedule_notrace() \
110 asm volatile ("call ___preempt_schedule_notrace" : ASM_CALL_CONSTRAINT)
112 extern asmlinkage void preempt_schedule_notrace(void);
113 #endif
115 #endif /* __ASM_PREEMPT_H */