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
  15 static inline int preempt_count(void)
  16 {
  17         return READ_ONCE(S390_lowcore.preempt_count) & ~PREEMPT_NEED_RESCHED;
  18 }
  19
  20 static 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
  32 #define init_task_preempt_count(p)      do { } while (0)
  33
  34 #define init_idle_preempt_count(p, cpu) do { \
  35         S390_lowcore.preempt_count = PREEMPT_ENABLED; \
  36 } while (0)
  37
  38 static inline void set_preempt_need_resched(void)
  39 {
  40         __atomic_and(~PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
  41 }
  42
  43 static inline void clear_preempt_need_resched(void)
  44 {
  45         __atomic_or(PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
  46 }
  47
  48 static inline bool test_preempt_need_resched(void)
  49 {
  50         return !(READ_ONCE(S390_lowcore.preempt_count) & PREEMPT_NEED_RESCHED);
  51 }
  52
  53 static inline void __preempt_count_add(int val)
  54 {
  55         if (__builtin_constant_p(val) && (val >= -128) && (val <= 127))
  56                 __atomic_add_const(val, &S390_lowcore.preempt_count);
  57         else
  58                 __atomic_add(val, &S390_lowcore.preempt_count);
  59 }
  60
  61 static inline void __preempt_count_sub(int val)
  62 {
  63         __preempt_count_add(-val);
  64 }
  65
  66 static inline bool __preempt_count_dec_and_test(void)
  67 {
  68         return __atomic_add(-1, &S390_lowcore.preempt_count) == 1;
  69 }
  70
  71 static inline bool should_resched(int preempt_offset)
  72 {
  73         return unlikely(READ_ONCE(S390_lowcore.preempt_count) ==
  74                         preempt_offset);
  75 }
  76
  77 #else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
  78
  79 #define PREEMPT_ENABLED (0)
  80
  81 static inline int preempt_count(void)
  82 {
  83         return READ_ONCE(S390_lowcore.preempt_count);
  84 }
  85
  86 static inline void preempt_count_set(int pc)
  87 {
  88         S390_lowcore.preempt_count = pc;
  89 }
  90
  91 #define init_task_preempt_count(p)      do { } while (0)
  92
  93 #define init_idle_preempt_count(p, cpu) do { \
  94         S390_lowcore.preempt_count = PREEMPT_ENABLED; \
  95 } while (0)
  96
  97 static inline void set_preempt_need_resched(void)
  98 {
  99 }
 100
 101 static inline void clear_preempt_need_resched(void)
 102 {
 103 }
 104
 105 static inline bool test_preempt_need_resched(void)
 106 {
 107         return false;
 108 }
 109
 110 static inline void __preempt_count_add(int val)
 111 {
 112         S390_lowcore.preempt_count += val;
 113 }
 114
 115 static inline void __preempt_count_sub(int val)
 116 {
 117         S390_lowcore.preempt_count -= val;
 118 }
 119
 120 static inline bool __preempt_count_dec_and_test(void)
 121 {
 122         return !--S390_lowcore.preempt_count && tif_need_resched();
 123 }
 124
 125 static inline bool should_resched(int preempt_offset)
 126 {
 127         return unlikely(preempt_count() == preempt_offset &&
 128                         tif_need_resched());
 129 }
 130
 131 #endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
 132
 133 #ifdef CONFIG_PREEMPT
 134 extern asmlinkage void preempt_schedule(void);
 135 #define __preempt_schedule() preempt_schedule()
 136 extern asmlinkage void preempt_schedule_notrace(void);
 137 #define __preempt_schedule_notrace() preempt_schedule_notrace()
 138 #endif /* CONFIG_PREEMPT */
 139
 140 #endif /* __ASM_PREEMPT_H */