libgcc/config/arm/linux-atomic.c

   1 /* Linux-specific atomic operations for ARM EABI.
   2    Copyright (C) 2008-2018 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; see linux-atomic-64bit.c for "long long" (64-bit)
  36    operations.  */
  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,   , +, signed char, 1, oldval)
 108 SUBWORD_SYNC_OP (sub,   , -, signed char, 1, oldval)
 109 SUBWORD_SYNC_OP (or,    , |, signed char, 1, oldval)
 110 SUBWORD_SYNC_OP (and,   , &, signed char, 1, oldval)
 111 SUBWORD_SYNC_OP (xor,   , ^, signed char, 1, oldval)
 112 SUBWORD_SYNC_OP (nand, ~, &, signed 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,   , +, signed char, 1, newval)
 143 SUBWORD_SYNC_OP (sub,   , -, signed char, 1, newval)
 144 SUBWORD_SYNC_OP (or,    , |, signed char, 1, newval)
 145 SUBWORD_SYNC_OP (and,   , &, signed char, 1, newval)
 146 SUBWORD_SYNC_OP (xor,   , ^, signed char, 1, newval)
 147 SUBWORD_SYNC_OP (nand, ~, &, signed 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 (__builtin_expect (oldval != actual_oldval, 0))
 159         return actual_oldval;
 160
 161       fail = __kernel_cmpxchg (actual_oldval, newval, ptr);
 162
 163       if (__builtin_expect (!fail, 1))
 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 (__builtin_expect (((actual_oldval & mask) >> shift) !=      \
 184                               ((unsigned int) oldval & MASK_##WIDTH), 0)) \
 185           return (actual_oldval & mask) >> shift;                       \
 186                                                                         \
 187         actual_newval = (actual_oldval & ~mask)                         \
 188                         | (((unsigned int) newval << shift) & mask);    \
 189                                                                         \
 190         fail = __kernel_cmpxchg (actual_oldval, actual_newval,          \
 191                                  wordptr);                              \
 192                                                                         \
 193       if (__builtin_expect (!fail, 1))                                  \
 194           return oldval;                                                \
 195       }                                                                 \
 196   }
 197
 198 SUBWORD_VAL_CAS (short,       2)
 199 SUBWORD_VAL_CAS (signed char, 1)
 200
 201 typedef unsigned char bool;
 202
 203 bool HIDDEN
 204 __sync_bool_compare_and_swap_4 (int *ptr, int oldval, int newval)
 205 {
 206   int failure = __kernel_cmpxchg (oldval, newval, ptr);
 207   return (failure == 0);
 208 }
 209
 210 #define SUBWORD_BOOL_CAS(TYPE, WIDTH)                                   \
 211   bool HIDDEN                                                           \
 212   __sync_bool_compare_and_swap_##WIDTH (TYPE *ptr, TYPE oldval,         \
 213                                         TYPE newval)                    \
 214   {                                                                     \
 215     TYPE actual_oldval                                                  \
 216       = __sync_val_compare_and_swap_##WIDTH (ptr, oldval, newval);      \
 217     return (oldval == actual_oldval);                                   \
 218   }
 219
 220 SUBWORD_BOOL_CAS (short,       2)
 221 SUBWORD_BOOL_CAS (signed char, 1)
 222
 223 void HIDDEN
 224 __sync_synchronize (void)
 225 {
 226   __kernel_dmb ();
 227 }
 228
 229 int HIDDEN
 230 __sync_lock_test_and_set_4 (int *ptr, int val)
 231 {
 232   int failure, oldval;
 233
 234   do {
 235     oldval = *ptr;
 236     failure = __kernel_cmpxchg (oldval, val, ptr);
 237   } while (failure != 0);
 238
 239   return oldval;
 240 }
 241
 242 #define SUBWORD_TEST_AND_SET(TYPE, WIDTH)                               \
 243   TYPE HIDDEN                                                           \
 244   __sync_lock_test_and_set_##WIDTH (TYPE *ptr, TYPE val)                \
 245   {                                                                     \
 246     int failure;                                                        \
 247     unsigned int oldval, newval, shift, mask;                           \
 248     int *wordptr = (int *) ((unsigned int) ptr & ~3);                   \
 249                                                                         \
 250     shift = (((unsigned int) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;      \
 251     mask = MASK_##WIDTH << shift;                                       \
 252                                                                         \
 253     do {                                                                \
 254       oldval = *wordptr;                                                \
 255       newval = (oldval & ~mask)                                         \
 256                | (((unsigned int) val << shift) & mask);                \
 257       failure = __kernel_cmpxchg (oldval, newval, wordptr);             \
 258     } while (failure != 0);                                             \
 259                                                                         \
 260     return (oldval & mask) >> shift;                                    \
 261   }
 262
 263 SUBWORD_TEST_AND_SET (short,       2)
 264 SUBWORD_TEST_AND_SET (signed char, 1)
 265
 266 #define SYNC_LOCK_RELEASE(TYPE, WIDTH)                                  \
 267   void HIDDEN                                                           \
 268   __sync_lock_release_##WIDTH (TYPE *ptr)                               \
 269   {                                                                     \
 270     /* All writes before this point must be seen before we release      \
 271        the lock itself.  */                                             \
 272     __kernel_dmb ();                                                    \
 273     *ptr = 0;                                                           \
 274   }
 275
 276 SYNC_LOCK_RELEASE (long long,   8)
 277 SYNC_LOCK_RELEASE (int,   4)
 278 SYNC_LOCK_RELEASE (short, 2)
 279 SYNC_LOCK_RELEASE (char,  1)