mirror of https://gitee.com/openkylin/linux.git
119 lines
3.1 KiB
C
119 lines
3.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef __ASM_PREEMPT_H
|
|
#define __ASM_PREEMPT_H
|
|
|
|
#include <asm/rmwcc.h>
|
|
#include <asm/percpu.h>
|
|
#include <linux/thread_info.h>
|
|
|
|
DECLARE_PER_CPU(int, __preempt_count);
|
|
|
|
/* We use the MSB mostly because its available */
|
|
#define PREEMPT_NEED_RESCHED 0x80000000
|
|
|
|
/*
|
|
* We use the PREEMPT_NEED_RESCHED bit as an inverted NEED_RESCHED such
|
|
* that a decrement hitting 0 means we can and should reschedule.
|
|
*/
|
|
#define PREEMPT_ENABLED (0 + PREEMPT_NEED_RESCHED)
|
|
|
|
/*
|
|
* We mask the PREEMPT_NEED_RESCHED bit so as not to confuse all current users
|
|
* that think a non-zero value indicates we cannot preempt.
|
|
*/
|
|
static __always_inline int preempt_count(void)
|
|
{
|
|
return raw_cpu_read_4(__preempt_count) & ~PREEMPT_NEED_RESCHED;
|
|
}
|
|
|
|
static __always_inline void preempt_count_set(int pc)
|
|
{
|
|
int old, new;
|
|
|
|
do {
|
|
old = raw_cpu_read_4(__preempt_count);
|
|
new = (old & PREEMPT_NEED_RESCHED) |
|
|
(pc & ~PREEMPT_NEED_RESCHED);
|
|
} while (raw_cpu_cmpxchg_4(__preempt_count, old, new) != old);
|
|
}
|
|
|
|
/*
|
|
* must be macros to avoid header recursion hell
|
|
*/
|
|
#define init_task_preempt_count(p) do { } while (0)
|
|
|
|
#define init_idle_preempt_count(p, cpu) do { \
|
|
per_cpu(__preempt_count, (cpu)) = PREEMPT_ENABLED; \
|
|
} while (0)
|
|
|
|
/*
|
|
* We fold the NEED_RESCHED bit into the preempt count such that
|
|
* preempt_enable() can decrement and test for needing to reschedule with a
|
|
* single instruction.
|
|
*
|
|
* We invert the actual bit, so that when the decrement hits 0 we know we both
|
|
* need to resched (the bit is cleared) and can resched (no preempt count).
|
|
*/
|
|
|
|
static __always_inline void set_preempt_need_resched(void)
|
|
{
|
|
raw_cpu_and_4(__preempt_count, ~PREEMPT_NEED_RESCHED);
|
|
}
|
|
|
|
static __always_inline void clear_preempt_need_resched(void)
|
|
{
|
|
raw_cpu_or_4(__preempt_count, PREEMPT_NEED_RESCHED);
|
|
}
|
|
|
|
static __always_inline bool test_preempt_need_resched(void)
|
|
{
|
|
return !(raw_cpu_read_4(__preempt_count) & PREEMPT_NEED_RESCHED);
|
|
}
|
|
|
|
/*
|
|
* The various preempt_count add/sub methods
|
|
*/
|
|
|
|
static __always_inline void __preempt_count_add(int val)
|
|
{
|
|
raw_cpu_add_4(__preempt_count, val);
|
|
}
|
|
|
|
static __always_inline void __preempt_count_sub(int val)
|
|
{
|
|
raw_cpu_add_4(__preempt_count, -val);
|
|
}
|
|
|
|
/*
|
|
* Because we keep PREEMPT_NEED_RESCHED set when we do _not_ need to reschedule
|
|
* a decrement which hits zero means we have no preempt_count and should
|
|
* reschedule.
|
|
*/
|
|
static __always_inline bool __preempt_count_dec_and_test(void)
|
|
{
|
|
return GEN_UNARY_RMWcc("decl", __preempt_count, e, __percpu_arg([var]));
|
|
}
|
|
|
|
/*
|
|
* Returns true when we need to resched and can (barring IRQ state).
|
|
*/
|
|
static __always_inline bool should_resched(int preempt_offset)
|
|
{
|
|
return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset);
|
|
}
|
|
|
|
#ifdef CONFIG_PREEMPTION
|
|
extern asmlinkage void ___preempt_schedule(void);
|
|
# define __preempt_schedule() \
|
|
asm volatile ("call ___preempt_schedule" : ASM_CALL_CONSTRAINT)
|
|
|
|
extern asmlinkage void preempt_schedule(void);
|
|
extern asmlinkage void ___preempt_schedule_notrace(void);
|
|
# define __preempt_schedule_notrace() \
|
|
asm volatile ("call ___preempt_schedule_notrace" : ASM_CALL_CONSTRAINT)
|
|
|
|
extern asmlinkage void preempt_schedule_notrace(void);
|
|
#endif
|
|
|
|
#endif /* __ASM_PREEMPT_H */
|