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