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 static inline void set_preempt_need_resched(void)
  33 {
  34         __atomic_and(~PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
  35 }
  36
  37 static inline void clear_preempt_need_resched(void)
  38 {
  39         __atomic_or(PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
  40 }
  41
  42 static inline bool test_preempt_need_resched(void)
  43 {
  44         return !(READ_ONCE(S390_lowcore.preempt_count) & PREEMPT_NEED_RESCHED);
  45 }
  46
  47 static 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
  55 static inline void __preempt_count_sub(int val)
  56 {
  57         __preempt_count_add(-val);
  58 }
  59
  60 static inline bool __preempt_count_dec_and_test(void)
  61 {
  62         return __atomic_add(-1, &S390_lowcore.preempt_count) == 1;
  63 }
  64
  65 static 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
  75 static inline int preempt_count(void)
  76 {
  77         return READ_ONCE(S390_lowcore.preempt_count);
  78 }
  79
  80 static inline void preempt_count_set(int pc)
  81 {
  82         S390_lowcore.preempt_count = pc;
  83 }
  84
  85 static inline void set_preempt_need_resched(void)
  86 {
  87 }
  88
  89 static inline void clear_preempt_need_resched(void)
  90 {
  91 }
  92
  93 static inline bool test_preempt_need_resched(void)
  94 {
  95         return false;
  96 }
  97
  98 static inline void __preempt_count_add(int val)
  99 {
 100         S390_lowcore.preempt_count += val;
 101 }
 102
 103 static inline void __preempt_count_sub(int val)
 104 {
 105         S390_lowcore.preempt_count -= val;
 106 }
 107
 108 static inline bool __preempt_count_dec_and_test(void)
 109 {
 110         return !--S390_lowcore.preempt_count && tif_need_resched();
 111 }
 112
 113 static 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
 126 extern void preempt_schedule(void);
 127 #define __preempt_schedule() preempt_schedule()
 128 extern void preempt_schedule_notrace(void);
 129 #define __preempt_schedule_notrace() preempt_schedule_notrace()
 130 #endif /* CONFIG_PREEMPTION */
 131
 132 #endif /* __ASM_PREEMPT_H */