libgcc/config/m68k/linux-atomic.c

   1 /* Linux-specific atomic operations for m68k Linux.
   2    Copyright (C) 2011, 2012 Free Software Foundation, Inc.
   3    Based on code contributed by CodeSourcery for ARM EABI Linux.
   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 /* Coldfire dropped the CAS instruction from the base M68K ISA.
  27
  28    GCC automatically issues a asm memory barrier when it encounters
  29    a __sync_synchronize builtin.  Thus, we do not need to define this
  30    builtin.
  31
  32    We implement byte, short and int versions of each atomic operation
  33    using the kernel helper defined below.  There is no support for
  34    64-bit operations yet.  */
  35
  36 #include <asm/unistd.h>
  37 #include <stdbool.h>
  38
  39 #ifndef __NR_atomic_cmpxchg_32
  40 #define __NR_atomic_cmpxchg_32  335
  41 #endif
  42
  43 /* Kernel helper for compare-and-exchange a 32-bit value.  */
  44 static inline unsigned
  45 __kernel_cmpxchg (unsigned *mem, unsigned oldval, unsigned newval)
  46 {
  47   register unsigned *a0 asm("a0") = mem;
  48   register unsigned d2 asm("d2") = oldval;
  49   register unsigned d1 asm("d1") = newval;
  50   register unsigned d0 asm("d0") = __NR_atomic_cmpxchg_32;
  51
  52   asm volatile ("trap #0"
  53                 : "=r"(d0), "=r"(d1), "=r"(a0)
  54                 : "r"(d0), "r"(d1), "r"(d2), "r"(a0)
  55                 : "memory", "a1");
  56
  57   return d0;
  58 }
  59
  60 #define HIDDEN __attribute__ ((visibility ("hidden")))
  61
  62 /* Big endian masks  */
  63 #define INVERT_MASK_1 24
  64 #define INVERT_MASK_2 16
  65
  66 #define MASK_1 0xffu
  67 #define MASK_2 0xffffu
  68
  69 #define NAME_oldval(OP, WIDTH) __sync_fetch_and_##OP##_##WIDTH
  70 #define NAME_newval(OP, WIDTH) __sync_##OP##_and_fetch_##WIDTH
  71
  72 #define WORD_SYNC_OP(OP, PFX_OP, INF_OP, RETURN)                        \
  73   unsigned HIDDEN                                                       \
  74   NAME##_##RETURN (OP, 4) (unsigned *ptr, unsigned val)                 \
  75   {                                                                     \
  76     unsigned oldval, newval, cmpval = *ptr;                             \
  77                                                                         \
  78     do {                                                                \
  79       oldval = cmpval;                                                  \
  80       newval = PFX_OP (oldval INF_OP val);                              \
  81       cmpval = __kernel_cmpxchg (ptr, oldval, newval);                  \
  82     } while (__builtin_expect (oldval != cmpval, 0));                   \
  83                                                                         \
  84     return RETURN;                                                      \
  85   }
  86
  87 #define SUBWORD_SYNC_OP(OP, PFX_OP, INF_OP, TYPE, WIDTH, RETURN)        \
  88   TYPE HIDDEN                                                           \
  89   NAME##_##RETURN (OP, WIDTH) (TYPE *ptr, TYPE sval)                    \
  90   {                                                                     \
  91     unsigned *wordptr = (unsigned *) ((unsigned long) ptr & ~3);        \
  92     unsigned int mask, shift, oldval, newval, cmpval, wval;             \
  93                                                                         \
  94     shift = (((unsigned long) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;     \
  95     mask = MASK_##WIDTH << shift;                                       \
  96     wval = (sval & MASK_##WIDTH) << shift;                              \
  97                                                                         \
  98     cmpval = *wordptr;                                                  \
  99     do {                                                                \
 100       oldval = cmpval;                                                  \
 101       newval = PFX_OP (oldval INF_OP wval);                             \
 102       newval = (newval & mask) | (oldval & ~mask);                      \
 103       cmpval = __kernel_cmpxchg (wordptr, oldval, newval);              \
 104     } while (__builtin_expect (oldval != cmpval, 0));                   \
 105                                                                         \
 106     return (RETURN >> shift) & MASK_##WIDTH;                            \
 107   }
 108
 109 WORD_SYNC_OP (add,   , +, oldval)
 110 WORD_SYNC_OP (sub,   , -, oldval)
 111 WORD_SYNC_OP (or,    , |, oldval)
 112 WORD_SYNC_OP (and,   , &, oldval)
 113 WORD_SYNC_OP (xor,   , ^, oldval)
 114 WORD_SYNC_OP (nand, ~, &, oldval)
 115
 116 SUBWORD_SYNC_OP (add,   , +, unsigned short, 2, oldval)
 117 SUBWORD_SYNC_OP (sub,   , -, unsigned short, 2, oldval)
 118 SUBWORD_SYNC_OP (or,    , |, unsigned short, 2, oldval)
 119 SUBWORD_SYNC_OP (and,   , &, unsigned short, 2, oldval)
 120 SUBWORD_SYNC_OP (xor,   , ^, unsigned short, 2, oldval)
 121 SUBWORD_SYNC_OP (nand, ~, &, unsigned short, 2, oldval)
 122
 123 SUBWORD_SYNC_OP (add,   , +, unsigned char, 1, oldval)
 124 SUBWORD_SYNC_OP (sub,   , -, unsigned char, 1, oldval)
 125 SUBWORD_SYNC_OP (or,    , |, unsigned char, 1, oldval)
 126 SUBWORD_SYNC_OP (and,   , &, unsigned char, 1, oldval)
 127 SUBWORD_SYNC_OP (xor,   , ^, unsigned char, 1, oldval)
 128 SUBWORD_SYNC_OP (nand, ~, &, unsigned char, 1, oldval)
 129
 130 WORD_SYNC_OP (add,   , +, newval)
 131 WORD_SYNC_OP (sub,   , -, newval)
 132 WORD_SYNC_OP (or,    , |, newval)
 133 WORD_SYNC_OP (and,   , &, newval)
 134 WORD_SYNC_OP (xor,   , ^, newval)
 135 WORD_SYNC_OP (nand, ~, &, newval)
 136
 137 SUBWORD_SYNC_OP (add,   , +, unsigned short, 2, newval)
 138 SUBWORD_SYNC_OP (sub,   , -, unsigned short, 2, newval)
 139 SUBWORD_SYNC_OP (or,    , |, unsigned short, 2, newval)
 140 SUBWORD_SYNC_OP (and,   , &, unsigned short, 2, newval)
 141 SUBWORD_SYNC_OP (xor,   , ^, unsigned short, 2, newval)
 142 SUBWORD_SYNC_OP (nand, ~, &, unsigned short, 2, newval)
 143
 144 SUBWORD_SYNC_OP (add,   , +, unsigned char, 1, newval)
 145 SUBWORD_SYNC_OP (sub,   , -, unsigned char, 1, newval)
 146 SUBWORD_SYNC_OP (or,    , |, unsigned char, 1, newval)
 147 SUBWORD_SYNC_OP (and,   , &, unsigned char, 1, newval)
 148 SUBWORD_SYNC_OP (xor,   , ^, unsigned char, 1, newval)
 149 SUBWORD_SYNC_OP (nand, ~, &, unsigned char, 1, newval)
 150
 151 unsigned HIDDEN
 152 __sync_val_compare_and_swap_4 (unsigned *ptr, unsigned oldval, unsigned newval)
 153 {
 154   return __kernel_cmpxchg (ptr, oldval, newval);
 155 }
 156
 157 bool HIDDEN
 158 __sync_bool_compare_and_swap_4 (unsigned *ptr, unsigned oldval,
 159                                 unsigned newval)
 160 {
 161   return __kernel_cmpxchg (ptr, oldval, newval) == oldval;
 162 }
 163
 164 #define SUBWORD_VAL_CAS(TYPE, WIDTH)                                    \
 165   TYPE HIDDEN                                                           \
 166   __sync_val_compare_and_swap_##WIDTH (TYPE *ptr, TYPE soldval,         \
 167                                        TYPE snewval)                    \
 168   {                                                                     \
 169     unsigned *wordptr = (unsigned *)((unsigned long) ptr & ~3);         \
 170     unsigned int mask, shift, woldval, wnewval;                         \
 171     unsigned oldval, newval, cmpval;                                    \
 172                                                                         \
 173     shift = (((unsigned long) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;     \
 174     mask = MASK_##WIDTH << shift;                                       \
 175     woldval = (soldval & MASK_##WIDTH) << shift;                        \
 176     wnewval = (snewval & MASK_##WIDTH) << shift;                        \
 177     cmpval = *wordptr;                                                  \
 178                                                                         \
 179     do {                                                                \
 180       oldval = cmpval;                                                  \
 181       if ((oldval & mask) != woldval)                                   \
 182         break;                                                          \
 183       newval = (oldval & ~mask) | wnewval;                              \
 184       cmpval = __kernel_cmpxchg (wordptr, oldval, newval);              \
 185     } while (__builtin_expect (oldval != cmpval, 0));                   \
 186                                                                         \
 187     return (oldval >> shift) & MASK_##WIDTH;                            \
 188   }
 189
 190 SUBWORD_VAL_CAS (unsigned short, 2)
 191 SUBWORD_VAL_CAS (unsigned char,  1)
 192
 193 #define SUBWORD_BOOL_CAS(TYPE, WIDTH)                                   \
 194   bool HIDDEN                                                           \
 195   __sync_bool_compare_and_swap_##WIDTH (TYPE *ptr, TYPE oldval,         \
 196                                         TYPE newval)                    \
 197   {                                                                     \
 198     return (__sync_val_compare_and_swap_##WIDTH (ptr, oldval, newval)   \
 199             == oldval);                                                 \
 200   }
 201
 202 SUBWORD_BOOL_CAS (unsigned short, 2)
 203 SUBWORD_BOOL_CAS (unsigned char,  1)
 204
 205 #undef NAME_oldval
 206 #define NAME_oldval(OP, WIDTH) __sync_lock_##OP##_##WIDTH
 207 #define COMMA ,
 208
 209 WORD_SYNC_OP (test_and_set, , COMMA, oldval)
 210 SUBWORD_SYNC_OP (test_and_set, , COMMA, unsigned char, 1, oldval)
 211 SUBWORD_SYNC_OP (test_and_set, , COMMA, unsigned short, 2, oldval)