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 /* 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 inline void __preempt_count_sub(int val) 63 { 64 __preempt_count_add(-val); 65 } 66 67 static inline bool __preempt_count_dec_and_test(void) 68 { 69 return __atomic_add(-1, &S390_lowcore.preempt_count) == 1; 70 } 71 72 static 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 inline int preempt_count(void) 83 { 84 return READ_ONCE(S390_lowcore.preempt_count); 85 } 86 87 static inline void preempt_count_set(int pc) 88 { 89 S390_lowcore.preempt_count = pc; 90 } 91 92 static inline void set_preempt_need_resched(void) 93 { 94 } 95 96 static inline void clear_preempt_need_resched(void) 97 { 98 } 99 100 static inline bool test_preempt_need_resched(void) 101 { 102 return false; 103 } 104 105 static inline void __preempt_count_add(int val) 106 { 107 S390_lowcore.preempt_count += val; 108 } 109 110 static inline void __preempt_count_sub(int val) 111 { 112 S390_lowcore.preempt_count -= val; 113 } 114 115 static inline bool __preempt_count_dec_and_test(void) 116 { 117 return !--S390_lowcore.preempt_count && tif_need_resched(); 118 } 119 120 static 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 */ 140