LXR linux/arch/s390/include/asm/preempt.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __ASM_PREEMPT_H
   3#define __ASM_PREEMPT_H
   4
   5#include <asm/current.h>
   6#include <linux/thread_info.h>
   7#include <asm/atomic_ops.h>
   8
   9#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
  10
  11/* We use the MSB mostly because its available */
  12#define PREEMPT_NEED_RESCHED    0x80000000
  13#define PREEMPT_ENABLED (0 + PREEMPT_NEED_RESCHED)
  14
  15static inline int preempt_count(void)
  16{
  17        return READ_ONCE(S390_lowcore.preempt_count) & ~PREEMPT_NEED_RESCHED;
  18}
  19
  20static inline void preempt_count_set(int pc)
  21{
  22        int old, new;
  23
  24        do {
  25                old = READ_ONCE(S390_lowcore.preempt_count);
  26                new = (old & PREEMPT_NEED_RESCHED) |
  27                        (pc & ~PREEMPT_NEED_RESCHED);
  28        } while (__atomic_cmpxchg(&S390_lowcore.preempt_count,
  29                                  old, new) != old);
  30}
  31
  32static inline void set_preempt_need_resched(void)
  33{
  34        __atomic_and(~PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
  35}
  36
  37static inline void clear_preempt_need_resched(void)
  38{
  39        __atomic_or(PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
  40}
  41
  42static inline bool test_preempt_need_resched(void)
  43{
  44        return !(READ_ONCE(S390_lowcore.preempt_count) & PREEMPT_NEED_RESCHED);
  45}
  46
  47static inline void __preempt_count_add(int val)
  48{
  49        if (__builtin_constant_p(val) && (val >= -128) && (val <= 127))
  50                __atomic_add_const(val, &S390_lowcore.preempt_count);
  51        else
  52                __atomic_add(val, &S390_lowcore.preempt_count);
  53}
  54
  55static inline void __preempt_count_sub(int val)
  56{
  57        __preempt_count_add(-val);
  58}
  59
  60static inline bool __preempt_count_dec_and_test(void)
  61{
  62        return __atomic_add(-1, &S390_lowcore.preempt_count) == 1;
  63}
  64
  65static inline bool should_resched(int preempt_offset)
  66{
  67        return unlikely(READ_ONCE(S390_lowcore.preempt_count) ==
  68                        preempt_offset);
  69}
  70
  71#else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
  72
  73#define PREEMPT_ENABLED (0)
  74
  75static inline int preempt_count(void)
  76{
  77        return READ_ONCE(S390_lowcore.preempt_count);
  78}
  79
  80static inline void preempt_count_set(int pc)
  81{
  82        S390_lowcore.preempt_count = pc;
  83}
  84
  85static inline void set_preempt_need_resched(void)
  86{
  87}
  88
  89static inline void clear_preempt_need_resched(void)
  90{
  91}
  92
  93static inline bool test_preempt_need_resched(void)
  94{
  95        return false;
  96}
  97
  98static inline void __preempt_count_add(int val)
  99{
 100        S390_lowcore.preempt_count += val;
 101}
 102
 103static inline void __preempt_count_sub(int val)
 104{
 105        S390_lowcore.preempt_count -= val;
 106}
 107
 108static inline bool __preempt_count_dec_and_test(void)
 109{
 110        return !--S390_lowcore.preempt_count && tif_need_resched();
 111}
 112
 113static inline bool should_resched(int preempt_offset)
 114{
 115        return unlikely(preempt_count() == preempt_offset &&
 116                        tif_need_resched());
 117}
 118
 119#endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
 120
 121#define init_task_preempt_count(p)      do { } while (0)
 122/* Deferred to CPU bringup time */
 123#define init_idle_preempt_count(p, cpu) do { } while (0)
 124
 125#ifdef CONFIG_PREEMPTION
 126extern void preempt_schedule(void);
 127#define __preempt_schedule() preempt_schedule()
 128extern void preempt_schedule_notrace(void);
 129#define __preempt_schedule_notrace() preempt_schedule_notrace()
 130#endif /* CONFIG_PREEMPTION */
 131
 132#endif /* __ASM_PREEMPT_H */
 133