arch/s390/include/asm/spinlock.h

   1 /*
   2  *  S390 version
   3  *    Copyright IBM Corp. 1999
   4  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
   5  *
   6  *  Derived from "include/asm-i386/spinlock.h"
   7  */
   8
   9 #ifndef __ASM_SPINLOCK_H
  10 #define __ASM_SPINLOCK_H
  11
  12 #include <linux/smp.h>
  13 #include <asm/atomic_ops.h>
  14 #include <asm/barrier.h>
  15 #include <asm/processor.h>
  16
  17 #define SPINLOCK_LOCKVAL (S390_lowcore.spinlock_lockval)
  18
  19 extern int spin_retry;
  20
  21 #ifndef CONFIG_SMP
  22 static inline bool arch_vcpu_is_preempted(int cpu) { return false; }
  23 #else
  24 bool arch_vcpu_is_preempted(int cpu);
  25 #endif
  26
  27 #define vcpu_is_preempted arch_vcpu_is_preempted
  28
  29 /*
  30  * Simple spin lock operations.  There are two variants, one clears IRQ's
  31  * on the local processor, one does not.
  32  *
  33  * We make no fairness assumptions. They have a cost.
  34  *
  35  * (the type definitions are in asm/spinlock_types.h)
  36  */
  37
  38 void arch_lock_relax(int cpu);
  39
  40 void arch_spin_lock_wait(arch_spinlock_t *);
  41 int arch_spin_trylock_retry(arch_spinlock_t *);
  42 void arch_spin_lock_wait_flags(arch_spinlock_t *, unsigned long flags);
  43
  44 static inline void arch_spin_relax(arch_spinlock_t *lock)
  45 {
  46         arch_lock_relax(lock->lock);
  47 }
  48
  49 static inline u32 arch_spin_lockval(int cpu)
  50 {
  51         return ~cpu;
  52 }
  53
  54 static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
  55 {
  56         return lock.lock == 0;
  57 }
  58
  59 static inline int arch_spin_is_locked(arch_spinlock_t *lp)
  60 {
  61         return READ_ONCE(lp->lock) != 0;
  62 }
  63
  64 static inline int arch_spin_trylock_once(arch_spinlock_t *lp)
  65 {
  66         barrier();
  67         return likely(arch_spin_value_unlocked(*lp) &&
  68                       __atomic_cmpxchg_bool(&lp->lock, 0, SPINLOCK_LOCKVAL));
  69 }
  70
  71 static inline void arch_spin_lock(arch_spinlock_t *lp)
  72 {
  73         if (!arch_spin_trylock_once(lp))
  74                 arch_spin_lock_wait(lp);
  75 }
  76
  77 static inline void arch_spin_lock_flags(arch_spinlock_t *lp,
  78                                         unsigned long flags)
  79 {
  80         if (!arch_spin_trylock_once(lp))
  81                 arch_spin_lock_wait_flags(lp, flags);
  82 }
  83
  84 static inline int arch_spin_trylock(arch_spinlock_t *lp)
  85 {
  86         if (!arch_spin_trylock_once(lp))
  87                 return arch_spin_trylock_retry(lp);
  88         return 1;
  89 }
  90
  91 static inline void arch_spin_unlock(arch_spinlock_t *lp)
  92 {
  93         typecheck(int, lp->lock);
  94         asm volatile(
  95                 "st     %1,%0\n"
  96                 : "+Q" (lp->lock)
  97                 : "d" (0)
  98                 : "cc", "memory");
  99 }
 100
 101 static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
 102 {
 103         while (arch_spin_is_locked(lock))
 104                 arch_spin_relax(lock);
 105         smp_acquire__after_ctrl_dep();
 106 }
 107
 108 /*
 109  * Read-write spinlocks, allowing multiple readers
 110  * but only one writer.
 111  *
 112  * NOTE! it is quite common to have readers in interrupts
 113  * but no interrupt writers. For those circumstances we
 114  * can "mix" irq-safe locks - any writer needs to get a
 115  * irq-safe write-lock, but readers can get non-irqsafe
 116  * read-locks.
 117  */
 118
 119 /**
 120  * read_can_lock - would read_trylock() succeed?
 121  * @lock: the rwlock in question.
 122  */
 123 #define arch_read_can_lock(x) ((int)(x)->lock >= 0)
 124
 125 /**
 126  * write_can_lock - would write_trylock() succeed?
 127  * @lock: the rwlock in question.
 128  */
 129 #define arch_write_can_lock(x) ((x)->lock == 0)
 130
 131 extern int _raw_read_trylock_retry(arch_rwlock_t *lp);
 132 extern int _raw_write_trylock_retry(arch_rwlock_t *lp);
 133
 134 #define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
 135 #define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
 136
 137 static inline int arch_read_trylock_once(arch_rwlock_t *rw)
 138 {
 139         int old = ACCESS_ONCE(rw->lock);
 140         return likely(old >= 0 &&
 141                       __atomic_cmpxchg_bool(&rw->lock, old, old + 1));
 142 }
 143
 144 static inline int arch_write_trylock_once(arch_rwlock_t *rw)
 145 {
 146         int old = ACCESS_ONCE(rw->lock);
 147         return likely(old == 0 &&
 148                       __atomic_cmpxchg_bool(&rw->lock, 0, 0x80000000));
 149 }
 150
 151 #ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
 152
 153 #define __RAW_OP_OR     "lao"
 154 #define __RAW_OP_AND    "lan"
 155 #define __RAW_OP_ADD    "laa"
 156
 157 #define __RAW_LOCK(ptr, op_val, op_string)              \
 158 ({                                                      \
 159         int old_val;                                    \
 160                                                         \
 161         typecheck(int *, ptr);                          \
 162         asm volatile(                                   \
 163                 op_string "     %0,%2,%1\n"             \
 164                 "bcr    14,0\n"                         \
 165                 : "=d" (old_val), "+Q" (*ptr)           \
 166                 : "d" (op_val)                          \
 167                 : "cc", "memory");                      \
 168         old_val;                                        \
 169 })
 170
 171 #define __RAW_UNLOCK(ptr, op_val, op_string)            \
 172 ({                                                      \
 173         int old_val;                                    \
 174                                                         \
 175         typecheck(int *, ptr);                          \
 176         asm volatile(                                   \
 177                 op_string "     %0,%2,%1\n"             \
 178                 : "=d" (old_val), "+Q" (*ptr)           \
 179                 : "d" (op_val)                          \
 180                 : "cc", "memory");                      \
 181         old_val;                                        \
 182 })
 183
 184 extern void _raw_read_lock_wait(arch_rwlock_t *lp);
 185 extern void _raw_write_lock_wait(arch_rwlock_t *lp, int prev);
 186
 187 static inline void arch_read_lock(arch_rwlock_t *rw)
 188 {
 189         int old;
 190
 191         old = __RAW_LOCK(&rw->lock, 1, __RAW_OP_ADD);
 192         if (old < 0)
 193                 _raw_read_lock_wait(rw);
 194 }
 195
 196 static inline void arch_read_unlock(arch_rwlock_t *rw)
 197 {
 198         __RAW_UNLOCK(&rw->lock, -1, __RAW_OP_ADD);
 199 }
 200
 201 static inline void arch_write_lock(arch_rwlock_t *rw)
 202 {
 203         int old;
 204
 205         old = __RAW_LOCK(&rw->lock, 0x80000000, __RAW_OP_OR);
 206         if (old != 0)
 207                 _raw_write_lock_wait(rw, old);
 208         rw->owner = SPINLOCK_LOCKVAL;
 209 }
 210
 211 static inline void arch_write_unlock(arch_rwlock_t *rw)
 212 {
 213         rw->owner = 0;
 214         __RAW_UNLOCK(&rw->lock, 0x7fffffff, __RAW_OP_AND);
 215 }
 216
 217 #else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
 218
 219 extern void _raw_read_lock_wait(arch_rwlock_t *lp);
 220 extern void _raw_write_lock_wait(arch_rwlock_t *lp);
 221
 222 static inline void arch_read_lock(arch_rwlock_t *rw)
 223 {
 224         if (!arch_read_trylock_once(rw))
 225                 _raw_read_lock_wait(rw);
 226 }
 227
 228 static inline void arch_read_unlock(arch_rwlock_t *rw)
 229 {
 230         int old;
 231
 232         do {
 233                 old = ACCESS_ONCE(rw->lock);
 234         } while (!__atomic_cmpxchg_bool(&rw->lock, old, old - 1));
 235 }
 236
 237 static inline void arch_write_lock(arch_rwlock_t *rw)
 238 {
 239         if (!arch_write_trylock_once(rw))
 240                 _raw_write_lock_wait(rw);
 241         rw->owner = SPINLOCK_LOCKVAL;
 242 }
 243
 244 static inline void arch_write_unlock(arch_rwlock_t *rw)
 245 {
 246         typecheck(int, rw->lock);
 247
 248         rw->owner = 0;
 249         asm volatile(
 250                 "st     %1,%0\n"
 251                 : "+Q" (rw->lock)
 252                 : "d" (0)
 253                 : "cc", "memory");
 254 }
 255
 256 #endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
 257
 258 static inline int arch_read_trylock(arch_rwlock_t *rw)
 259 {
 260         if (!arch_read_trylock_once(rw))
 261                 return _raw_read_trylock_retry(rw);
 262         return 1;
 263 }
 264
 265 static inline int arch_write_trylock(arch_rwlock_t *rw)
 266 {
 267         if (!arch_write_trylock_once(rw) && !_raw_write_trylock_retry(rw))
 268                 return 0;
 269         rw->owner = SPINLOCK_LOCKVAL;
 270         return 1;
 271 }
 272
 273 static inline void arch_read_relax(arch_rwlock_t *rw)
 274 {
 275         arch_lock_relax(rw->owner);
 276 }
 277
 278 static inline void arch_write_relax(arch_rwlock_t *rw)
 279 {
 280         arch_lock_relax(rw->owner);
 281 }
 282
 283 #endif /* __ASM_SPINLOCK_H */