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 #define PREEMPT_ENABLED (0 + PREEMPT_NEED_RESCHED)
  12
  13 static inline int preempt_count(void)
  14 {
  15         return READ_ONCE(S390_lowcore.preempt_count) & ~PREEMPT_NEED_RESCHED;
  16 }
  17
  18 static inline void preempt_count_set(int pc)
  19 {
  20         int old, new;
  21
  22         do {
  23                 old = READ_ONCE(S390_lowcore.preempt_count);
  24                 new = (old & PREEMPT_NEED_RESCHED) |
  25                         (pc & ~PREEMPT_NEED_RESCHED);
  26         } while (__atomic_cmpxchg(&S390_lowcore.preempt_count,
  27                                   old, new) != old);
  28 }
  29
  30 #define init_task_preempt_count(p)      do { } while (0)
  31
  32 #define init_idle_preempt_count(p, cpu) do { \
  33         S390_lowcore.preempt_count = PREEMPT_ENABLED; \
  34 } while (0)
  35
  36 static inline void set_preempt_need_resched(void)
  37 {
  38         __atomic_and(~PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
  39 }
  40
  41 static inline void clear_preempt_need_resched(void)
  42 {
  43         __atomic_or(PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
  44 }
  45
  46 static inline bool test_preempt_need_resched(void)
  47 {
  48         return !(READ_ONCE(S390_lowcore.preempt_count) & PREEMPT_NEED_RESCHED);
  49 }
  50
  51 static inline void __preempt_count_add(int val)
  52 {
  53         /*
  54          * With some obscure config options and CONFIG_PROFILE_ALL_BRANCHES
  55          * enabled, gcc 12 fails to handle __builtin_constant_p().
  56          */
  57         if (!IS_ENABLED(CONFIG_PROFILE_ALL_BRANCHES)) {
  58                 if (__builtin_constant_p(val) && (val >= -128) && (val <= 127)) {
  59                         __atomic_add_const(val, &S390_lowcore.preempt_count);
  60                         return;
  61                 }
  62         }
  63         __atomic_add(val, &S390_lowcore.preempt_count);
  64 }
  65
  66 static inline void __preempt_count_sub(int val)
  67 {
  68         __preempt_count_add(-val);
  69 }
  70
  71 static inline bool __preempt_count_dec_and_test(void)
  72 {
  73         return __atomic_add(-1, &S390_lowcore.preempt_count) == 1;
  74 }
  75
  76 static inline bool should_resched(int preempt_offset)
  77 {
  78         return unlikely(READ_ONCE(S390_lowcore.preempt_count) ==
  79                         preempt_offset);
  80 }
  81
  82 #else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
  83
  84 #define PREEMPT_ENABLED (0)
  85
  86 static inline int preempt_count(void)
  87 {
  88         return READ_ONCE(S390_lowcore.preempt_count);
  89 }
  90
  91 static inline void preempt_count_set(int pc)
  92 {
  93         S390_lowcore.preempt_count = pc;
  94 }
  95
  96 #define init_task_preempt_count(p)      do { } while (0)
  97
  98 #define init_idle_preempt_count(p, cpu) do { \
  99         S390_lowcore.preempt_count = PREEMPT_ENABLED; \
 100 } while (0)
 101
 102 static inline void set_preempt_need_resched(void)
 103 {
 104 }
 105
 106 static inline void clear_preempt_need_resched(void)
 107 {
 108 }
 109
 110 static inline bool test_preempt_need_resched(void)
 111 {
 112         return false;
 113 }
 114
 115 static inline void __preempt_count_add(int val)
 116 {
 117         S390_lowcore.preempt_count += val;
 118 }
 119
 120 static inline void __preempt_count_sub(int val)
 121 {
 122         S390_lowcore.preempt_count -= val;
 123 }
 124
 125 static inline bool __preempt_count_dec_and_test(void)
 126 {
 127         return !--S390_lowcore.preempt_count && tif_need_resched();
 128 }
 129
 130 static inline bool should_resched(int preempt_offset)
 131 {
 132         return unlikely(preempt_count() == preempt_offset &&
 133                         tif_need_resched());
 134 }
 135
 136 #endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
 137
 138 #ifdef CONFIG_PREEMPT
 139 extern asmlinkage void preempt_schedule(void);
 140 #define __preempt_schedule() preempt_schedule()
 141 extern asmlinkage void preempt_schedule_notrace(void);
 142 #define __preempt_schedule_notrace() preempt_schedule_notrace()
 143 #endif /* CONFIG_PREEMPT */
 144
 145 #endif /* __ASM_PREEMPT_H */