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