arch/x86/lib/memcpy_32.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/string.h>
   3 #include <linux/export.h>
   4
   5 #undef memcpy
   6 #undef memset
   7 #undef memmove
   8
   9 __visible void *memcpy(void *to, const void *from, size_t n)
  10 {
  11         return __memcpy(to, from, n);
  12 }
  13 EXPORT_SYMBOL(memcpy);
  14
  15 __visible void *memset(void *s, int c, size_t count)
  16 {
  17         return __memset(s, c, count);
  18 }
  19 EXPORT_SYMBOL(memset);
  20
  21 __visible void *memmove(void *dest, const void *src, size_t n)
  22 {
  23         int d0,d1,d2,d3,d4,d5;
  24         char *ret = dest;
  25
  26         __asm__ __volatile__(
  27                 /* Handle more 16 bytes in loop */
  28                 "cmp $0x10, %0\n\t"
  29                 "jb     1f\n\t"
  30
  31                 /* Decide forward/backward copy mode */
  32                 "cmp %2, %1\n\t"
  33                 "jb     2f\n\t"
  34
  35                 /*
  36                  * movs instruction have many startup latency
  37                  * so we handle small size by general register.
  38                  */
  39                 "cmp  $680, %0\n\t"
  40                 "jb 3f\n\t"
  41                 /*
  42                  * movs instruction is only good for aligned case.
  43                  */
  44                 "mov %1, %3\n\t"
  45                 "xor %2, %3\n\t"
  46                 "and $0xff, %3\n\t"
  47                 "jz 4f\n\t"
  48                 "3:\n\t"
  49                 "sub $0x10, %0\n\t"
  50
  51                 /*
  52                  * We gobble 16 bytes forward in each loop.
  53                  */
  54                 "3:\n\t"
  55                 "sub $0x10, %0\n\t"
  56                 "mov 0*4(%1), %3\n\t"
  57                 "mov 1*4(%1), %4\n\t"
  58                 "mov  %3, 0*4(%2)\n\t"
  59                 "mov  %4, 1*4(%2)\n\t"
  60                 "mov 2*4(%1), %3\n\t"
  61                 "mov 3*4(%1), %4\n\t"
  62                 "mov  %3, 2*4(%2)\n\t"
  63                 "mov  %4, 3*4(%2)\n\t"
  64                 "lea  0x10(%1), %1\n\t"
  65                 "lea  0x10(%2), %2\n\t"
  66                 "jae 3b\n\t"
  67                 "add $0x10, %0\n\t"
  68                 "jmp 1f\n\t"
  69
  70                 /*
  71                  * Handle data forward by movs.
  72                  */
  73                 ".p2align 4\n\t"
  74                 "4:\n\t"
  75                 "mov -4(%1, %0), %3\n\t"
  76                 "lea -4(%2, %0), %4\n\t"
  77                 "shr $2, %0\n\t"
  78                 "rep movsl\n\t"
  79                 "mov %3, (%4)\n\t"
  80                 "jmp 11f\n\t"
  81                 /*
  82                  * Handle data backward by movs.
  83                  */
  84                 ".p2align 4\n\t"
  85                 "6:\n\t"
  86                 "mov (%1), %3\n\t"
  87                 "mov %2, %4\n\t"
  88                 "lea -4(%1, %0), %1\n\t"
  89                 "lea -4(%2, %0), %2\n\t"
  90                 "shr $2, %0\n\t"
  91                 "std\n\t"
  92                 "rep movsl\n\t"
  93                 "mov %3,(%4)\n\t"
  94                 "cld\n\t"
  95                 "jmp 11f\n\t"
  96
  97                 /*
  98                  * Start to prepare for backward copy.
  99                  */
 100                 ".p2align 4\n\t"
 101                 "2:\n\t"
 102                 "cmp  $680, %0\n\t"
 103                 "jb 5f\n\t"
 104                 "mov %1, %3\n\t"
 105                 "xor %2, %3\n\t"
 106                 "and $0xff, %3\n\t"
 107                 "jz 6b\n\t"
 108
 109                 /*
 110                  * Calculate copy position to tail.
 111                  */
 112                 "5:\n\t"
 113                 "add %0, %1\n\t"
 114                 "add %0, %2\n\t"
 115                 "sub $0x10, %0\n\t"
 116
 117                 /*
 118                  * We gobble 16 bytes backward in each loop.
 119                  */
 120                 "7:\n\t"
 121                 "sub $0x10, %0\n\t"
 122
 123                 "mov -1*4(%1), %3\n\t"
 124                 "mov -2*4(%1), %4\n\t"
 125                 "mov  %3, -1*4(%2)\n\t"
 126                 "mov  %4, -2*4(%2)\n\t"
 127                 "mov -3*4(%1), %3\n\t"
 128                 "mov -4*4(%1), %4\n\t"
 129                 "mov  %3, -3*4(%2)\n\t"
 130                 "mov  %4, -4*4(%2)\n\t"
 131                 "lea  -0x10(%1), %1\n\t"
 132                 "lea  -0x10(%2), %2\n\t"
 133                 "jae 7b\n\t"
 134                 /*
 135                  * Calculate copy position to head.
 136                  */
 137                 "add $0x10, %0\n\t"
 138                 "sub %0, %1\n\t"
 139                 "sub %0, %2\n\t"
 140
 141                 /*
 142                  * Move data from 8 bytes to 15 bytes.
 143                  */
 144                 ".p2align 4\n\t"
 145                 "1:\n\t"
 146                 "cmp $8, %0\n\t"
 147                 "jb 8f\n\t"
 148                 "mov 0*4(%1), %3\n\t"
 149                 "mov 1*4(%1), %4\n\t"
 150                 "mov -2*4(%1, %0), %5\n\t"
 151                 "mov -1*4(%1, %0), %1\n\t"
 152
 153                 "mov  %3, 0*4(%2)\n\t"
 154                 "mov  %4, 1*4(%2)\n\t"
 155                 "mov  %5, -2*4(%2, %0)\n\t"
 156                 "mov  %1, -1*4(%2, %0)\n\t"
 157                 "jmp 11f\n\t"
 158
 159                 /*
 160                  * Move data from 4 bytes to 7 bytes.
 161                  */
 162                 ".p2align 4\n\t"
 163                 "8:\n\t"
 164                 "cmp $4, %0\n\t"
 165                 "jb 9f\n\t"
 166                 "mov 0*4(%1), %3\n\t"
 167                 "mov -1*4(%1, %0), %4\n\t"
 168                 "mov  %3, 0*4(%2)\n\t"
 169                 "mov  %4, -1*4(%2, %0)\n\t"
 170                 "jmp 11f\n\t"
 171
 172                 /*
 173                  * Move data from 2 bytes to 3 bytes.
 174                  */
 175                 ".p2align 4\n\t"
 176                 "9:\n\t"
 177                 "cmp $2, %0\n\t"
 178                 "jb 10f\n\t"
 179                 "movw 0*2(%1), %%dx\n\t"
 180                 "movw -1*2(%1, %0), %%bx\n\t"
 181                 "movw %%dx, 0*2(%2)\n\t"
 182                 "movw %%bx, -1*2(%2, %0)\n\t"
 183                 "jmp 11f\n\t"
 184
 185                 /*
 186                  * Move data for 1 byte.
 187                  */
 188                 ".p2align 4\n\t"
 189                 "10:\n\t"
 190                 "cmp $1, %0\n\t"
 191                 "jb 11f\n\t"
 192                 "movb (%1), %%cl\n\t"
 193                 "movb %%cl, (%2)\n\t"
 194                 ".p2align 4\n\t"
 195                 "11:"
 196                 : "=&c" (d0), "=&S" (d1), "=&D" (d2),
 197                   "=r" (d3),"=r" (d4), "=r"(d5)
 198                 :"0" (n),
 199                  "1" (src),
 200                  "2" (dest)
 201                 :"memory");
 202
 203         return ret;
 204
 205 }
 206 EXPORT_SYMBOL(memmove);