tools/testing/selftests/rcutorture/formal/srcu-cbmc/src/locks.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef LOCKS_H
   3 #define LOCKS_H
   4
   5 #include <limits.h>
   6 #include <pthread.h>
   7 #include <stdbool.h>
   8
   9 #include "assume.h"
  10 #include "bug_on.h"
  11 #include "preempt.h"
  12
  13 int nondet_int(void);
  14
  15 #define __acquire(x)
  16 #define __acquires(x)
  17 #define __release(x)
  18 #define __releases(x)
  19
  20 /* Only use one lock mechanism. Select which one. */
  21 #ifdef PTHREAD_LOCK
  22 struct lock_impl {
  23         pthread_mutex_t mutex;
  24 };
  25
  26 static inline void lock_impl_lock(struct lock_impl *lock)
  27 {
  28         BUG_ON(pthread_mutex_lock(&lock->mutex));
  29 }
  30
  31 static inline void lock_impl_unlock(struct lock_impl *lock)
  32 {
  33         BUG_ON(pthread_mutex_unlock(&lock->mutex));
  34 }
  35
  36 static inline bool lock_impl_trylock(struct lock_impl *lock)
  37 {
  38         int err = pthread_mutex_trylock(&lock->mutex);
  39
  40         if (!err)
  41                 return true;
  42         else if (err == EBUSY)
  43                 return false;
  44         BUG();
  45 }
  46
  47 static inline void lock_impl_init(struct lock_impl *lock)
  48 {
  49         pthread_mutex_init(&lock->mutex, NULL);
  50 }
  51
  52 #define LOCK_IMPL_INITIALIZER {.mutex = PTHREAD_MUTEX_INITIALIZER}
  53
  54 #else /* !defined(PTHREAD_LOCK) */
  55 /* Spinlock that assumes that it always gets the lock immediately. */
  56
  57 struct lock_impl {
  58         bool locked;
  59 };
  60
  61 static inline bool lock_impl_trylock(struct lock_impl *lock)
  62 {
  63 #ifdef RUN
  64         /* TODO: Should this be a test and set? */
  65         return __sync_bool_compare_and_swap(&lock->locked, false, true);
  66 #else
  67         __CPROVER_atomic_begin();
  68         bool old_locked = lock->locked;
  69         lock->locked = true;
  70         __CPROVER_atomic_end();
  71
  72         /* Minimal barrier to prevent accesses leaking out of lock. */
  73         __CPROVER_fence("RRfence", "RWfence");
  74
  75         return !old_locked;
  76 #endif
  77 }
  78
  79 static inline void lock_impl_lock(struct lock_impl *lock)
  80 {
  81         /*
  82          * CBMC doesn't support busy waiting, so just assume that the
  83          * lock is available.
  84          */
  85         assume(lock_impl_trylock(lock));
  86
  87         /*
  88          * If the lock was already held by this thread then the assumption
  89          * is unsatisfiable (deadlock).
  90          */
  91 }
  92
  93 static inline void lock_impl_unlock(struct lock_impl *lock)
  94 {
  95 #ifdef RUN
  96         BUG_ON(!__sync_bool_compare_and_swap(&lock->locked, true, false));
  97 #else
  98         /* Minimal barrier to prevent accesses leaking out of lock. */
  99         __CPROVER_fence("RWfence", "WWfence");
 100
 101         __CPROVER_atomic_begin();
 102         bool old_locked = lock->locked;
 103         lock->locked = false;
 104         __CPROVER_atomic_end();
 105
 106         BUG_ON(!old_locked);
 107 #endif
 108 }
 109
 110 static inline void lock_impl_init(struct lock_impl *lock)
 111 {
 112         lock->locked = false;
 113 }
 114
 115 #define LOCK_IMPL_INITIALIZER {.locked = false}
 116
 117 #endif /* !defined(PTHREAD_LOCK) */
 118
 119 /*
 120  * Implement spinlocks using the lock mechanism. Wrap the lock to prevent mixing
 121  * locks of different types.
 122  */
 123 typedef struct {
 124         struct lock_impl internal_lock;
 125 } spinlock_t;
 126
 127 #define SPIN_LOCK_UNLOCKED {.internal_lock = LOCK_IMPL_INITIALIZER}
 128 #define __SPIN_LOCK_UNLOCKED(x) SPIN_LOCK_UNLOCKED
 129 #define DEFINE_SPINLOCK(x) spinlock_t x = SPIN_LOCK_UNLOCKED
 130
 131 static inline void spin_lock_init(spinlock_t *lock)
 132 {
 133         lock_impl_init(&lock->internal_lock);
 134 }
 135
 136 static inline void spin_lock(spinlock_t *lock)
 137 {
 138         /*
 139          * Spin locks also need to be removed in order to eliminate all
 140          * memory barriers. They are only used by the write side anyway.
 141          */
 142 #ifndef NO_SYNC_SMP_MB
 143         preempt_disable();
 144         lock_impl_lock(&lock->internal_lock);
 145 #endif
 146 }
 147
 148 static inline void spin_unlock(spinlock_t *lock)
 149 {
 150 #ifndef NO_SYNC_SMP_MB
 151         lock_impl_unlock(&lock->internal_lock);
 152         preempt_enable();
 153 #endif
 154 }
 155
 156 /* Don't bother with interrupts */
 157 #define spin_lock_irq(lock) spin_lock(lock)
 158 #define spin_unlock_irq(lock) spin_unlock(lock)
 159 #define spin_lock_irqsave(lock, flags) spin_lock(lock)
 160 #define spin_unlock_irqrestore(lock, flags) spin_unlock(lock)
 161
 162 /*
 163  * This is supposed to return an int, but I think that a bool should work as
 164  * well.
 165  */
 166 static inline bool spin_trylock(spinlock_t *lock)
 167 {
 168 #ifndef NO_SYNC_SMP_MB
 169         preempt_disable();
 170         return lock_impl_trylock(&lock->internal_lock);
 171 #else
 172         return true;
 173 #endif
 174 }
 175
 176 struct completion {
 177         /* Hopefuly this won't overflow. */
 178         unsigned int count;
 179 };
 180
 181 #define COMPLETION_INITIALIZER(x) {.count = 0}
 182 #define DECLARE_COMPLETION(x) struct completion x = COMPLETION_INITIALIZER(x)
 183 #define DECLARE_COMPLETION_ONSTACK(x) DECLARE_COMPLETION(x)
 184
 185 static inline void init_completion(struct completion *c)
 186 {
 187         c->count = 0;
 188 }
 189
 190 static inline void wait_for_completion(struct completion *c)
 191 {
 192         unsigned int prev_count = __sync_fetch_and_sub(&c->count, 1);
 193
 194         assume(prev_count);
 195 }
 196
 197 static inline void complete(struct completion *c)
 198 {
 199         unsigned int prev_count = __sync_fetch_and_add(&c->count, 1);
 200
 201         BUG_ON(prev_count == UINT_MAX);
 202 }
 203
 204 /* This function probably isn't very useful for CBMC. */
 205 static inline bool try_wait_for_completion(struct completion *c)
 206 {
 207         BUG();
 208 }
 209
 210 static inline bool completion_done(struct completion *c)
 211 {
 212         return c->count;
 213 }
 214
 215 /* TODO: Implement complete_all */
 216 static inline void complete_all(struct completion *c)
 217 {
 218         BUG();
 219 }
 220
 221 #endif