libgcc/config/pa/linux-atomic.c

   1 /* Linux-specific atomic operations for PA Linux.
   2    Copyright (C) 2008-2014 Free Software Foundation, Inc.
   3    Based on code contributed by CodeSourcery for ARM EABI Linux.
   4    Modifications for PA Linux by Helge Deller <deller@gmx.de>
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 Under Section 7 of GPL version 3, you are granted additional
  19 permissions described in the GCC Runtime Library Exception, version
  20 3.1, as published by the Free Software Foundation.
  21
  22 You should have received a copy of the GNU General Public License and
  23 a copy of the GCC Runtime Library Exception along with this program;
  24 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  25 <http://www.gnu.org/licenses/>.  */
  26
  27 #define EFAULT  14
  28 #define EBUSY   16
  29 #define ENOSYS 251
  30
  31 /* All PA-RISC implementations supported by linux have strongly
  32    ordered loads and stores.  Only cache flushes and purges can be
  33    delayed.  The data cache implementations are all globally
  34    coherent.  Thus, there is no need to synchonize memory accesses.
  35
  36    GCC automatically issues a asm memory barrier when it encounters
  37    a __sync_synchronize builtin.  Thus, we do not need to define this
  38    builtin.
  39
  40    We implement byte, short and int versions of each atomic operation
  41    using the kernel helper defined below.  There is no support for
  42    64-bit operations yet.  */
  43
  44 /* A privileged instruction to crash a userspace program with SIGILL.  */
  45 #define ABORT_INSTRUCTION asm ("iitlbp %r0,(%sr0, %r0)")
  46
  47 /* Determine kernel LWS function call (0=32-bit, 1=64-bit userspace).  */
  48 #define LWS_CAS (sizeof(unsigned long) == 4 ? 0 : 1)
  49
  50 /* Kernel helper for compare-and-exchange a 32-bit value.  */
  51 static inline long
  52 __kernel_cmpxchg (int oldval, int newval, int *mem)
  53 {
  54   register unsigned long lws_mem asm("r26") = (unsigned long) (mem);
  55   register long lws_ret   asm("r28");
  56   register long lws_errno asm("r21");
  57   register int lws_old asm("r25") = oldval;
  58   register int lws_new asm("r24") = newval;
  59   asm volatile (        "ble    0xb0(%%sr2, %%r0)       \n\t"
  60                         "ldi    %5, %%r20               \n\t"
  61         : "=r" (lws_ret), "=r" (lws_errno), "=r" (lws_mem),
  62           "=r" (lws_old), "=r" (lws_new)
  63         : "i" (LWS_CAS), "2" (lws_mem), "3" (lws_old), "4" (lws_new)
  64         : "r1", "r20", "r22", "r23", "r29", "r31", "memory"
  65   );
  66   if (__builtin_expect (lws_errno == -EFAULT || lws_errno == -ENOSYS, 0))
  67     ABORT_INSTRUCTION;
  68
  69   /* If the kernel LWS call succeeded (lws_errno == 0), lws_ret contains
  70      the old value from memory.  If this value is equal to OLDVAL, the
  71      new value was written to memory.  If not, return -EBUSY.  */
  72   if (!lws_errno && lws_ret != oldval)
  73     lws_errno = -EBUSY;
  74
  75   return lws_errno;
  76 }
  77
  78 #define HIDDEN __attribute__ ((visibility ("hidden")))
  79
  80 /* Big endian masks  */
  81 #define INVERT_MASK_1 24
  82 #define INVERT_MASK_2 16
  83
  84 #define MASK_1 0xffu
  85 #define MASK_2 0xffffu
  86
  87 #define FETCH_AND_OP_WORD(OP, PFX_OP, INF_OP)                           \
  88   int HIDDEN                                                            \
  89   __sync_fetch_and_##OP##_4 (int *ptr, int val)                         \
  90   {                                                                     \
  91     int failure, tmp;                                                   \
  92                                                                         \
  93     do {                                                                \
  94       tmp = *ptr;                                                       \
  95       failure = __kernel_cmpxchg (tmp, PFX_OP (tmp INF_OP val), ptr);   \
  96     } while (failure != 0);                                             \
  97                                                                         \
  98     return tmp;                                                         \
  99   }
 100
 101 FETCH_AND_OP_WORD (add,   , +)
 102 FETCH_AND_OP_WORD (sub,   , -)
 103 FETCH_AND_OP_WORD (or,    , |)
 104 FETCH_AND_OP_WORD (and,   , &)
 105 FETCH_AND_OP_WORD (xor,   , ^)
 106 FETCH_AND_OP_WORD (nand, ~, &)
 107
 108 #define NAME_oldval(OP, WIDTH) __sync_fetch_and_##OP##_##WIDTH
 109 #define NAME_newval(OP, WIDTH) __sync_##OP##_and_fetch_##WIDTH
 110
 111 /* Implement both __sync_<op>_and_fetch and __sync_fetch_and_<op> for
 112    subword-sized quantities.  */
 113
 114 #define SUBWORD_SYNC_OP(OP, PFX_OP, INF_OP, TYPE, WIDTH, RETURN)        \
 115   TYPE HIDDEN                                                           \
 116   NAME##_##RETURN (OP, WIDTH) (TYPE *ptr, TYPE val)                     \
 117   {                                                                     \
 118     int *wordptr = (int *) ((unsigned long) ptr & ~3);                  \
 119     unsigned int mask, shift, oldval, newval;                           \
 120     int failure;                                                        \
 121                                                                         \
 122     shift = (((unsigned long) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;     \
 123     mask = MASK_##WIDTH << shift;                                       \
 124                                                                         \
 125     do {                                                                \
 126       oldval = *wordptr;                                                \
 127       newval = ((PFX_OP (((oldval & mask) >> shift)                     \
 128                          INF_OP (unsigned int) val)) << shift) & mask;  \
 129       newval |= oldval & ~mask;                                         \
 130       failure = __kernel_cmpxchg (oldval, newval, wordptr);             \
 131     } while (failure != 0);                                             \
 132                                                                         \
 133     return (RETURN & mask) >> shift;                                    \
 134   }
 135
 136 SUBWORD_SYNC_OP (add,   , +, unsigned short, 2, oldval)
 137 SUBWORD_SYNC_OP (sub,   , -, unsigned short, 2, oldval)
 138 SUBWORD_SYNC_OP (or,    , |, unsigned short, 2, oldval)
 139 SUBWORD_SYNC_OP (and,   , &, unsigned short, 2, oldval)
 140 SUBWORD_SYNC_OP (xor,   , ^, unsigned short, 2, oldval)
 141 SUBWORD_SYNC_OP (nand, ~, &, unsigned short, 2, oldval)
 142
 143 SUBWORD_SYNC_OP (add,   , +, unsigned char, 1, oldval)
 144 SUBWORD_SYNC_OP (sub,   , -, unsigned char, 1, oldval)
 145 SUBWORD_SYNC_OP (or,    , |, unsigned char, 1, oldval)
 146 SUBWORD_SYNC_OP (and,   , &, unsigned char, 1, oldval)
 147 SUBWORD_SYNC_OP (xor,   , ^, unsigned char, 1, oldval)
 148 SUBWORD_SYNC_OP (nand, ~, &, unsigned char, 1, oldval)
 149
 150 #define OP_AND_FETCH_WORD(OP, PFX_OP, INF_OP)                           \
 151   int HIDDEN                                                            \
 152   __sync_##OP##_and_fetch_4 (int *ptr, int val)                         \
 153   {                                                                     \
 154     int tmp, failure;                                                   \
 155                                                                         \
 156     do {                                                                \
 157       tmp = *ptr;                                                       \
 158       failure = __kernel_cmpxchg (tmp, PFX_OP (tmp INF_OP val), ptr);   \
 159     } while (failure != 0);                                             \
 160                                                                         \
 161     return PFX_OP (tmp INF_OP val);                                     \
 162   }
 163
 164 OP_AND_FETCH_WORD (add,   , +)
 165 OP_AND_FETCH_WORD (sub,   , -)
 166 OP_AND_FETCH_WORD (or,    , |)
 167 OP_AND_FETCH_WORD (and,   , &)
 168 OP_AND_FETCH_WORD (xor,   , ^)
 169 OP_AND_FETCH_WORD (nand, ~, &)
 170
 171 SUBWORD_SYNC_OP (add,   , +, unsigned short, 2, newval)
 172 SUBWORD_SYNC_OP (sub,   , -, unsigned short, 2, newval)
 173 SUBWORD_SYNC_OP (or,    , |, unsigned short, 2, newval)
 174 SUBWORD_SYNC_OP (and,   , &, unsigned short, 2, newval)
 175 SUBWORD_SYNC_OP (xor,   , ^, unsigned short, 2, newval)
 176 SUBWORD_SYNC_OP (nand, ~, &, unsigned short, 2, newval)
 177
 178 SUBWORD_SYNC_OP (add,   , +, unsigned char, 1, newval)
 179 SUBWORD_SYNC_OP (sub,   , -, unsigned char, 1, newval)
 180 SUBWORD_SYNC_OP (or,    , |, unsigned char, 1, newval)
 181 SUBWORD_SYNC_OP (and,   , &, unsigned char, 1, newval)
 182 SUBWORD_SYNC_OP (xor,   , ^, unsigned char, 1, newval)
 183 SUBWORD_SYNC_OP (nand, ~, &, unsigned char, 1, newval)
 184
 185 int HIDDEN
 186 __sync_val_compare_and_swap_4 (int *ptr, int oldval, int newval)
 187 {
 188   int actual_oldval, fail;
 189
 190   while (1)
 191     {
 192       actual_oldval = *ptr;
 193
 194       if (__builtin_expect (oldval != actual_oldval, 0))
 195         return actual_oldval;
 196
 197       fail = __kernel_cmpxchg (actual_oldval, newval, ptr);
 198
 199       if (__builtin_expect (!fail, 1))
 200         return actual_oldval;
 201     }
 202 }
 203
 204 #define SUBWORD_VAL_CAS(TYPE, WIDTH)                                    \
 205   TYPE HIDDEN                                                           \
 206   __sync_val_compare_and_swap_##WIDTH (TYPE *ptr, TYPE oldval,          \
 207                                        TYPE newval)                     \
 208   {                                                                     \
 209     int *wordptr = (int *)((unsigned long) ptr & ~3), fail;             \
 210     unsigned int mask, shift, actual_oldval, actual_newval;             \
 211                                                                         \
 212     shift = (((unsigned long) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;     \
 213     mask = MASK_##WIDTH << shift;                                       \
 214                                                                         \
 215     while (1)                                                           \
 216       {                                                                 \
 217         actual_oldval = *wordptr;                                       \
 218                                                                         \
 219         if (__builtin_expect (((actual_oldval & mask) >> shift)         \
 220                               != (unsigned int) oldval, 0))             \
 221           return (actual_oldval & mask) >> shift;                       \
 222                                                                         \
 223         actual_newval = (actual_oldval & ~mask)                         \
 224                         | (((unsigned int) newval << shift) & mask);    \
 225                                                                         \
 226         fail = __kernel_cmpxchg (actual_oldval, actual_newval,          \
 227                                  wordptr);                              \
 228                                                                         \
 229         if (__builtin_expect (!fail, 1))                                \
 230           return (actual_oldval & mask) >> shift;                       \
 231       }                                                                 \
 232   }
 233
 234 SUBWORD_VAL_CAS (unsigned short, 2)
 235 SUBWORD_VAL_CAS (unsigned char,  1)
 236
 237 typedef unsigned char bool;
 238
 239 bool HIDDEN
 240 __sync_bool_compare_and_swap_4 (int *ptr, int oldval, int newval)
 241 {
 242   int failure = __kernel_cmpxchg (oldval, newval, ptr);
 243   return (failure == 0);
 244 }
 245
 246 #define SUBWORD_BOOL_CAS(TYPE, WIDTH)                                   \
 247   bool HIDDEN                                                           \
 248   __sync_bool_compare_and_swap_##WIDTH (TYPE *ptr, TYPE oldval,         \
 249                                         TYPE newval)                    \
 250   {                                                                     \
 251     TYPE actual_oldval                                                  \
 252       = __sync_val_compare_and_swap_##WIDTH (ptr, oldval, newval);      \
 253     return (oldval == actual_oldval);                                   \
 254   }
 255
 256 SUBWORD_BOOL_CAS (unsigned short, 2)
 257 SUBWORD_BOOL_CAS (unsigned char,  1)
 258
 259 int HIDDEN
 260 __sync_lock_test_and_set_4 (int *ptr, int val)
 261 {
 262   int failure, oldval;
 263
 264   do {
 265     oldval = *ptr;
 266     failure = __kernel_cmpxchg (oldval, val, ptr);
 267   } while (failure != 0);
 268
 269   return oldval;
 270 }
 271
 272 #define SUBWORD_TEST_AND_SET(TYPE, WIDTH)                               \
 273   TYPE HIDDEN                                                           \
 274   __sync_lock_test_and_set_##WIDTH (TYPE *ptr, TYPE val)                \
 275   {                                                                     \
 276     int failure;                                                        \
 277     unsigned int oldval, newval, shift, mask;                           \
 278     int *wordptr = (int *) ((unsigned long) ptr & ~3);                  \
 279                                                                         \
 280     shift = (((unsigned long) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;     \
 281     mask = MASK_##WIDTH << shift;                                       \
 282                                                                         \
 283     do {                                                                \
 284       oldval = *wordptr;                                                \
 285       newval = (oldval & ~mask)                                         \
 286                | (((unsigned int) val << shift) & mask);                \
 287       failure = __kernel_cmpxchg (oldval, newval, wordptr);             \
 288     } while (failure != 0);                                             \
 289                                                                         \
 290     return (oldval & mask) >> shift;                                    \
 291   }
 292
 293 SUBWORD_TEST_AND_SET (unsigned short, 2)
 294 SUBWORD_TEST_AND_SET (unsigned char,  1)
 295
 296 #define SYNC_LOCK_RELEASE(TYPE, WIDTH)                                  \
 297   void HIDDEN                                                           \
 298   __sync_lock_release_##WIDTH (TYPE *ptr)                               \
 299   {                                                                     \
 300     *ptr = 0;                                                           \
 301   }
 302
 303 SYNC_LOCK_RELEASE (int,   4)
 304 SYNC_LOCK_RELEASE (short, 2)
 305 SYNC_LOCK_RELEASE (char,  1)