gcc/config/arm/linux-atomic.c

   1 /* Linux-specific atomic operations for ARM EABI.
   2    Copyright (C) 2008, 2009 Free Software Foundation, Inc.
   3    Contributed by CodeSourcery.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 <http://www.gnu.org/licenses/>.  */
  25
  26 /* Kernel helper for compare-and-exchange.  */
  27 typedef int (__kernel_cmpxchg_t) (int oldval, int newval, int *ptr);
  28 #define __kernel_cmpxchg (*(__kernel_cmpxchg_t *) 0xffff0fc0)
  29
  30 /* Kernel helper for memory barrier.  */
  31 typedef void (__kernel_dmb_t) (void);
  32 #define __kernel_dmb (*(__kernel_dmb_t *) 0xffff0fa0)
  33
  34 /* Note: we implement byte, short and int versions of atomic operations using
  35    the above kernel helpers, but there is no support for "long long" (64-bit)
  36    operations as yet.  */
  37
  38 #define HIDDEN __attribute__ ((visibility ("hidden")))
  39
  40 #ifdef __ARMEL__
  41 #define INVERT_MASK_1 0
  42 #define INVERT_MASK_2 0
  43 #else
  44 #define INVERT_MASK_1 24
  45 #define INVERT_MASK_2 16
  46 #endif
  47
  48 #define MASK_1 0xffu
  49 #define MASK_2 0xffffu
  50
  51 #define FETCH_AND_OP_WORD(OP, PFX_OP, INF_OP)                           \
  52   int HIDDEN                                                            \
  53   __sync_fetch_and_##OP##_4 (int *ptr, int val)                         \
  54   {                                                                     \
  55     int failure, tmp;                                                   \
  56                                                                         \
  57     do {                                                                \
  58       tmp = *ptr;                                                       \
  59       failure = __kernel_cmpxchg (tmp, PFX_OP tmp INF_OP val, ptr);     \
  60     } while (failure != 0);                                             \
  61                                                                         \
  62     return tmp;                                                         \
  63   }
  64
  65 FETCH_AND_OP_WORD (add,   , +)
  66 FETCH_AND_OP_WORD (sub,   , -)
  67 FETCH_AND_OP_WORD (or,    , |)
  68 FETCH_AND_OP_WORD (and,   , &)
  69 FETCH_AND_OP_WORD (xor,   , ^)
  70 FETCH_AND_OP_WORD (nand, ~, &)
  71
  72 #define NAME_oldval(OP, WIDTH) __sync_fetch_and_##OP##_##WIDTH
  73 #define NAME_newval(OP, WIDTH) __sync_##OP##_and_fetch_##WIDTH
  74
  75 /* Implement both __sync_<op>_and_fetch and __sync_fetch_and_<op> for
  76    subword-sized quantities.  */
  77
  78 #define SUBWORD_SYNC_OP(OP, PFX_OP, INF_OP, TYPE, WIDTH, RETURN)        \
  79   TYPE HIDDEN                                                           \
  80   NAME##_##RETURN (OP, WIDTH) (TYPE *ptr, TYPE val)                     \
  81   {                                                                     \
  82     int *wordptr = (int *) ((unsigned int) ptr & ~3);                   \
  83     unsigned int mask, shift, oldval, newval;                           \
  84     int failure;                                                        \
  85                                                                         \
  86     shift = (((unsigned int) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;      \
  87     mask = MASK_##WIDTH << shift;                                       \
  88                                                                         \
  89     do {                                                                \
  90       oldval = *wordptr;                                                \
  91       newval = ((PFX_OP ((oldval & mask) >> shift)                      \
  92                  INF_OP (unsigned int) val) << shift) & mask;           \
  93       newval |= oldval & ~mask;                                         \
  94       failure = __kernel_cmpxchg (oldval, newval, wordptr);             \
  95     } while (failure != 0);                                             \
  96                                                                         \
  97     return (RETURN & mask) >> shift;                                    \
  98   }
  99
 100 SUBWORD_SYNC_OP (add,   , +, short, 2, oldval)
 101 SUBWORD_SYNC_OP (sub,   , -, short, 2, oldval)
 102 SUBWORD_SYNC_OP (or,    , |, short, 2, oldval)
 103 SUBWORD_SYNC_OP (and,   , &, short, 2, oldval)
 104 SUBWORD_SYNC_OP (xor,   , ^, short, 2, oldval)
 105 SUBWORD_SYNC_OP (nand, ~, &, short, 2, oldval)
 106
 107 SUBWORD_SYNC_OP (add,   , +, char, 1, oldval)
 108 SUBWORD_SYNC_OP (sub,   , -, char, 1, oldval)
 109 SUBWORD_SYNC_OP (or,    , |, char, 1, oldval)
 110 SUBWORD_SYNC_OP (and,   , &, char, 1, oldval)
 111 SUBWORD_SYNC_OP (xor,   , ^, char, 1, oldval)
 112 SUBWORD_SYNC_OP (nand, ~, &, char, 1, oldval)
 113
 114 #define OP_AND_FETCH_WORD(OP, PFX_OP, INF_OP)                           \
 115   int HIDDEN                                                            \
 116   __sync_##OP##_and_fetch_4 (int *ptr, int val)                         \
 117   {                                                                     \
 118     int tmp, failure;                                                   \
 119                                                                         \
 120     do {                                                                \
 121       tmp = *ptr;                                                       \
 122       failure = __kernel_cmpxchg (tmp, PFX_OP tmp INF_OP val, ptr);     \
 123     } while (failure != 0);                                             \
 124                                                                         \
 125     return PFX_OP tmp INF_OP val;                                       \
 126   }
 127
 128 OP_AND_FETCH_WORD (add,   , +)
 129 OP_AND_FETCH_WORD (sub,   , -)
 130 OP_AND_FETCH_WORD (or,    , |)
 131 OP_AND_FETCH_WORD (and,   , &)
 132 OP_AND_FETCH_WORD (xor,   , ^)
 133 OP_AND_FETCH_WORD (nand, ~, &)
 134
 135 SUBWORD_SYNC_OP (add,   , +, short, 2, newval)
 136 SUBWORD_SYNC_OP (sub,   , -, short, 2, newval)
 137 SUBWORD_SYNC_OP (or,    , |, short, 2, newval)
 138 SUBWORD_SYNC_OP (and,   , &, short, 2, newval)
 139 SUBWORD_SYNC_OP (xor,   , ^, short, 2, newval)
 140 SUBWORD_SYNC_OP (nand, ~, &, short, 2, newval)
 141
 142 SUBWORD_SYNC_OP (add,   , +, char, 1, newval)
 143 SUBWORD_SYNC_OP (sub,   , -, char, 1, newval)
 144 SUBWORD_SYNC_OP (or,    , |, char, 1, newval)
 145 SUBWORD_SYNC_OP (and,   , &, char, 1, newval)
 146 SUBWORD_SYNC_OP (xor,   , ^, char, 1, newval)
 147 SUBWORD_SYNC_OP (nand, ~, &, char, 1, newval)
 148
 149 int HIDDEN
 150 __sync_val_compare_and_swap_4 (int *ptr, int oldval, int newval)
 151 {
 152   int actual_oldval, fail;
 153
 154   while (1)
 155     {
 156       actual_oldval = *ptr;
 157
 158       if (oldval != actual_oldval)
 159         return actual_oldval;
 160
 161       fail = __kernel_cmpxchg (actual_oldval, newval, ptr);
 162
 163       if (!fail)
 164         return oldval;
 165     }
 166 }
 167
 168 #define SUBWORD_VAL_CAS(TYPE, WIDTH)                                    \
 169   TYPE HIDDEN                                                           \
 170   __sync_val_compare_and_swap_##WIDTH (TYPE *ptr, TYPE oldval,          \
 171                                        TYPE newval)                     \
 172   {                                                                     \
 173     int *wordptr = (int *)((unsigned int) ptr & ~3), fail;              \
 174     unsigned int mask, shift, actual_oldval, actual_newval;             \
 175                                                                         \
 176     shift = (((unsigned int) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;      \
 177     mask = MASK_##WIDTH << shift;                                       \
 178                                                                         \
 179     while (1)                                                           \
 180       {                                                                 \
 181         actual_oldval = *wordptr;                                       \
 182                                                                         \
 183         if (((actual_oldval & mask) >> shift) != (unsigned int) oldval) \
 184           return (actual_oldval & mask) >> shift;                       \
 185                                                                         \
 186         actual_newval = (actual_oldval & ~mask)                         \
 187                         | (((unsigned int) newval << shift) & mask);    \
 188                                                                         \
 189         fail = __kernel_cmpxchg (actual_oldval, actual_newval,          \
 190                                  wordptr);                              \
 191                                                                         \
 192         if (!fail)                                                      \
 193           return oldval;                                                \
 194       }                                                                 \
 195   }
 196
 197 SUBWORD_VAL_CAS (short, 2)
 198 SUBWORD_VAL_CAS (char,  1)
 199
 200 typedef unsigned char bool;
 201
 202 bool HIDDEN
 203 __sync_bool_compare_and_swap_4 (int *ptr, int oldval, int newval)
 204 {
 205   int failure = __kernel_cmpxchg (oldval, newval, ptr);
 206   return (failure == 0);
 207 }
 208
 209 #define SUBWORD_BOOL_CAS(TYPE, WIDTH)                                   \
 210   bool HIDDEN                                                           \
 211   __sync_bool_compare_and_swap_##WIDTH (TYPE *ptr, TYPE oldval,         \
 212                                         TYPE newval)                    \
 213   {                                                                     \
 214     TYPE actual_oldval                                                  \
 215       = __sync_val_compare_and_swap_##WIDTH (ptr, oldval, newval);      \
 216     return (oldval == actual_oldval);                                   \
 217   }
 218
 219 SUBWORD_BOOL_CAS (short, 2)
 220 SUBWORD_BOOL_CAS (char,  1)
 221
 222 void HIDDEN
 223 __sync_synchronize (void)
 224 {
 225   __kernel_dmb ();
 226 }
 227
 228 int HIDDEN
 229 __sync_lock_test_and_set_4 (int *ptr, int val)
 230 {
 231   int failure, oldval;
 232
 233   do {
 234     oldval = *ptr;
 235     failure = __kernel_cmpxchg (oldval, val, ptr);
 236   } while (failure != 0);
 237
 238   return oldval;
 239 }
 240
 241 #define SUBWORD_TEST_AND_SET(TYPE, WIDTH)                               \
 242   TYPE HIDDEN                                                           \
 243   __sync_lock_test_and_set_##WIDTH (TYPE *ptr, TYPE val)                \
 244   {                                                                     \
 245     int failure;                                                        \
 246     unsigned int oldval, newval, shift, mask;                           \
 247     int *wordptr = (int *) ((unsigned int) ptr & ~3);                   \
 248                                                                         \
 249     shift = (((unsigned int) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;      \
 250     mask = MASK_##WIDTH << shift;                                       \
 251                                                                         \
 252     do {                                                                \
 253       oldval = *wordptr;                                                \
 254       newval = (oldval & ~mask)                                         \
 255                | (((unsigned int) val << shift) & mask);                \
 256       failure = __kernel_cmpxchg (oldval, newval, wordptr);             \
 257     } while (failure != 0);                                             \
 258                                                                         \
 259     return (oldval & mask) >> shift;                                    \
 260   }
 261
 262 SUBWORD_TEST_AND_SET (short, 2)
 263 SUBWORD_TEST_AND_SET (char,  1)
 264
 265 #define SYNC_LOCK_RELEASE(TYPE, WIDTH)                                  \
 266   void HIDDEN                                                           \
 267   __sync_lock_release_##WIDTH (TYPE *ptr)                               \
 268   {                                                                     \
 269     /* All writes before this point must be seen before we release      \
 270        the lock itself.  */                                             \
 271     __kernel_dmb ();                                                    \
 272     *ptr = 0;                                                           \
 273   }
 274
 275 SYNC_LOCK_RELEASE (int,   4)
 276 SYNC_LOCK_RELEASE (short, 2)
 277 SYNC_LOCK_RELEASE (char,  1)