include/internal/refcount.h

   1 /*
   2  * Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9 #ifndef HEADER_INTERNAL_REFCOUNT_H
  10 # define HEADER_INTERNAL_REFCOUNT_H
  11
  12 /* Used to checking reference counts, most while doing perl5 stuff :-) */
  13 # if defined(OPENSSL_NO_STDIO)
  14 #  if defined(REF_PRINT)
  15 #   error "REF_PRINT requires stdio"
  16 #  endif
  17 # endif
  18
  19 # if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L \
  20      && !defined(__STDC_NO_ATOMICS__)
  21 #  include <stdatomic.h>
  22 #  define HAVE_C11_ATOMICS
  23 # endif
  24
  25 # if defined(HAVE_C11_ATOMICS) && defined(ATOMIC_INT_LOCK_FREE) \
  26      && ATOMIC_INT_LOCK_FREE > 0
  27
  28 #  define HAVE_ATOMICS 1
  29
  30 typedef _Atomic int CRYPTO_REF_COUNT;
  31
  32 static inline int CRYPTO_UP_REF(_Atomic int *val, int *ret, void *lock)
  33 {
  34     *ret = atomic_fetch_add_explicit(val, 1, memory_order_relaxed) + 1;
  35     return 1;
  36 }
  37
  38 /*
  39  * Changes to shared structure other than reference counter have to be
  40  * serialized. And any kind of serialization implies a release fence. This
  41  * means that by the time reference counter is decremented all other
  42  * changes are visible on all processors. Hence decrement itself can be
  43  * relaxed. In case it hits zero, object will be destructed. Since it's
  44  * last use of the object, destructor programmer might reason that access
  45  * to mutable members doesn't have to be serialized anymore, which would
  46  * otherwise imply an acquire fence. Hence conditional acquire fence...
  47  */
  48 static inline int CRYPTO_DOWN_REF(_Atomic int *val, int *ret, void *lock)
  49 {
  50     *ret = atomic_fetch_sub_explicit(val, 1, memory_order_relaxed) - 1;
  51     if (*ret == 0)
  52         atomic_thread_fence(memory_order_acquire);
  53     return 1;
  54 }
  55
  56 # elif defined(__GNUC__) && defined(__ATOMIC_RELAXED) && __GCC_ATOMIC_INT_LOCK_FREE > 0
  57
  58 #  define HAVE_ATOMICS 1
  59
  60 typedef int CRYPTO_REF_COUNT;
  61
  62 static __inline__ int CRYPTO_UP_REF(int *val, int *ret, void *lock)
  63 {
  64     *ret = __atomic_fetch_add(val, 1, __ATOMIC_RELAXED) + 1;
  65     return 1;
  66 }
  67
  68 static __inline__ int CRYPTO_DOWN_REF(int *val, int *ret, void *lock)
  69 {
  70     *ret = __atomic_fetch_sub(val, 1, __ATOMIC_RELAXED) - 1;
  71     if (*ret == 0)
  72         __atomic_thread_fence(__ATOMIC_ACQUIRE);
  73     return 1;
  74 }
  75
  76 # elif defined(_MSC_VER) && _MSC_VER>=1200
  77
  78 #  define HAVE_ATOMICS 1
  79
  80 typedef volatile int CRYPTO_REF_COUNT;
  81
  82 #  if (defined(_M_ARM) && _M_ARM>=7) || defined(_M_ARM64)
  83 #   include <intrin.h>
  84 #   if defined(_M_ARM64) && !defined(_ARM_BARRIER_ISH)
  85 #    define _ARM_BARRIER_ISH _ARM64_BARRIER_ISH
  86 #   endif
  87
  88 static __inline int CRYPTO_UP_REF(volatile int *val, int *ret, void *lock)
  89 {
  90     *ret = _InterlockedExchangeAdd_nf(val, 1) + 1;
  91     return 1;
  92 }
  93
  94 static __inline int CRYPTO_DOWN_REF(volatile int *val, int *ret, void *lock)
  95 {
  96     *ret = _InterlockedExchangeAdd_nf(val, -1) - 1;
  97     if (*ret == 0)
  98         __dmb(_ARM_BARRIER_ISH);
  99     return 1;
 100 }
 101 #  else
 102 #   pragma intrinsic(_InterlockedExchangeAdd)
 103
 104 static __inline int CRYPTO_UP_REF(volatile int *val, int *ret, void *lock)
 105 {
 106     *ret = _InterlockedExchangeAdd(val, 1) + 1;
 107     return 1;
 108 }
 109
 110 static __inline int CRYPTO_DOWN_REF(volatile int *val, int *ret, void *lock)
 111 {
 112     *ret = _InterlockedExchangeAdd(val, -1) - 1;
 113     return 1;
 114 }
 115 #  endif
 116
 117 # else
 118
 119 typedef int CRYPTO_REF_COUNT;
 120
 121 # define CRYPTO_UP_REF(val, ret, lock) CRYPTO_atomic_add(val, 1, ret, lock)
 122 # define CRYPTO_DOWN_REF(val, ret, lock) CRYPTO_atomic_add(val, -1, ret, lock)
 123
 124 # endif
 125
 126 # if !defined(NDEBUG) && !defined(OPENSSL_NO_STDIO)
 127 #  define REF_ASSERT_ISNT(test) \
 128     (void)((test) ? (OPENSSL_die("refcount error", __FILE__, __LINE__), 1) : 0)
 129 # else
 130 #  define REF_ASSERT_ISNT(i)
 131 # endif
 132
 133 # ifdef REF_PRINT
 134 #  define REF_PRINT_COUNT(a, b) \
 135         fprintf(stderr, "%p:%4d:%s\n", b, b->references, a)
 136 # else
 137 #  define REF_PRINT_COUNT(a, b)
 138 # endif
 139
 140 #endif