arch/tile/lib/memcpy_64.c

   1 /*
   2  * Copyright 2011 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  */
  14
  15 #include <linux/types.h>
  16 #include <linux/string.h>
  17 #include <linux/module.h>
  18 /* EXPORT_SYMBOL() is in arch/tile/lib/exports.c since this should be asm. */
  19
  20 /* Must be 8 bytes in size. */
  21 #define op_t uint64_t
  22
  23 /* Threshold value for when to enter the unrolled loops. */
  24 #define OP_T_THRES      16
  25
  26 #if CHIP_L2_LINE_SIZE() != 64
  27 #error "Assumes 64 byte line size"
  28 #endif
  29
  30 /* How many cache lines ahead should we prefetch? */
  31 #define PREFETCH_LINES_AHEAD 4
  32
  33 /*
  34  * Provide "base versions" of load and store for the normal code path.
  35  * The kernel provides other versions for userspace copies.
  36  */
  37 #define ST(p, v) (*(p) = (v))
  38 #define LD(p) (*(p))
  39
  40 #ifndef USERCOPY_FUNC
  41 #define ST1 ST
  42 #define ST2 ST
  43 #define ST4 ST
  44 #define ST8 ST
  45 #define LD1 LD
  46 #define LD2 LD
  47 #define LD4 LD
  48 #define LD8 LD
  49 #define RETVAL dstv
  50 void *memcpy(void *__restrict dstv, const void *__restrict srcv, size_t n)
  51 #else
  52 /*
  53  * Special kernel version will provide implementation of the LDn/STn
  54  * macros to return a count of uncopied bytes due to mm fault.
  55  */
  56 #define RETVAL 0
  57 int __attribute__((optimize("omit-frame-pointer")))
  58 USERCOPY_FUNC(void *__restrict dstv, const void *__restrict srcv, size_t n)
  59 #endif
  60 {
  61         char *__restrict dst1 = (char *)dstv;
  62         const char *__restrict src1 = (const char *)srcv;
  63         const char *__restrict src1_end;
  64         const char *__restrict prefetch;
  65         op_t *__restrict dst8;    /* 8-byte pointer to destination memory. */
  66         op_t final; /* Final bytes to write to trailing word, if any */
  67         long i;
  68
  69         if (n < 16) {
  70                 for (; n; n--)
  71                         ST1(dst1++, LD1(src1++));
  72                 return RETVAL;
  73         }
  74
  75         /*
  76          * Locate the end of source memory we will copy.  Don't
  77          * prefetch past this.
  78          */
  79         src1_end = src1 + n - 1;
  80
  81         /* Prefetch ahead a few cache lines, but not past the end. */
  82         prefetch = src1;
  83         for (i = 0; i < PREFETCH_LINES_AHEAD; i++) {
  84                 __insn_prefetch(prefetch);
  85                 prefetch += CHIP_L2_LINE_SIZE();
  86                 prefetch = (prefetch < src1_end) ? prefetch : src1;
  87         }
  88
  89         /* Copy bytes until dst is word-aligned. */
  90         for (; (uintptr_t)dst1 & (sizeof(op_t) - 1); n--)
  91                 ST1(dst1++, LD1(src1++));
  92
  93         /* 8-byte pointer to destination memory. */
  94         dst8 = (op_t *)dst1;
  95
  96         if (__builtin_expect((uintptr_t)src1 & (sizeof(op_t) - 1), 0)) {
  97                 /* Unaligned copy. */
  98
  99                 op_t  tmp0 = 0, tmp1 = 0, tmp2, tmp3;
 100                 const op_t *src8 = (const op_t *) ((uintptr_t)src1 &
 101                                                    -sizeof(op_t));
 102                 const void *srci = (void *)src1;
 103                 int m;
 104
 105                 m = (CHIP_L2_LINE_SIZE() << 2) -
 106                         (((uintptr_t)dst8) & ((CHIP_L2_LINE_SIZE() << 2) - 1));
 107                 m = (n < m) ? n : m;
 108                 m /= sizeof(op_t);
 109
 110                 /* Copy until 'dst' is cache-line-aligned. */
 111                 n -= (sizeof(op_t) * m);
 112
 113                 switch (m % 4) {
 114                 case 0:
 115                         if (__builtin_expect(!m, 0))
 116                                 goto _M0;
 117                         tmp1 = LD8(src8++);
 118                         tmp2 = LD8(src8++);
 119                         goto _8B3;
 120                 case 2:
 121                         m += 2;
 122                         tmp3 = LD8(src8++);
 123                         tmp0 = LD8(src8++);
 124                         goto _8B1;
 125                 case 3:
 126                         m += 1;
 127                         tmp2 = LD8(src8++);
 128                         tmp3 = LD8(src8++);
 129                         goto _8B2;
 130                 case 1:
 131                         m--;
 132                         tmp0 = LD8(src8++);
 133                         tmp1 = LD8(src8++);
 134                         if (__builtin_expect(!m, 0))
 135                                 goto _8B0;
 136                 }
 137
 138                 do {
 139                         tmp2 = LD8(src8++);
 140                         tmp0 =  __insn_dblalign(tmp0, tmp1, srci);
 141                         ST8(dst8++, tmp0);
 142 _8B3:
 143                         tmp3 = LD8(src8++);
 144                         tmp1 = __insn_dblalign(tmp1, tmp2, srci);
 145                         ST8(dst8++, tmp1);
 146 _8B2:
 147                         tmp0 = LD8(src8++);
 148                         tmp2 = __insn_dblalign(tmp2, tmp3, srci);
 149                         ST8(dst8++, tmp2);
 150 _8B1:
 151                         tmp1 = LD8(src8++);
 152                         tmp3 = __insn_dblalign(tmp3, tmp0, srci);
 153                         ST8(dst8++, tmp3);
 154                         m -= 4;
 155                 } while (m);
 156
 157 _8B0:
 158                 tmp0 = __insn_dblalign(tmp0, tmp1, srci);
 159                 ST8(dst8++, tmp0);
 160                 src8--;
 161
 162 _M0:
 163                 if (__builtin_expect(n >= CHIP_L2_LINE_SIZE(), 0)) {
 164                         op_t tmp4, tmp5, tmp6, tmp7, tmp8;
 165
 166                         prefetch = ((const char *)src8) +
 167                                 CHIP_L2_LINE_SIZE() * PREFETCH_LINES_AHEAD;
 168
 169                         for (tmp0 = LD8(src8++); n >= CHIP_L2_LINE_SIZE();
 170                              n -= CHIP_L2_LINE_SIZE()) {
 171                                 /* Prefetch and advance to next line to
 172                                    prefetch, but don't go past the end.  */
 173                                 __insn_prefetch(prefetch);
 174
 175                                 /* Make sure prefetch got scheduled
 176                                    earlier.  */
 177                                 __asm__ ("" : : : "memory");
 178
 179                                 prefetch += CHIP_L2_LINE_SIZE();
 180                                 prefetch = (prefetch < src1_end) ? prefetch :
 181                                         (const char *) src8;
 182
 183                                 tmp1 = LD8(src8++);
 184                                 tmp2 = LD8(src8++);
 185                                 tmp3 = LD8(src8++);
 186                                 tmp4 = LD8(src8++);
 187                                 tmp5 = LD8(src8++);
 188                                 tmp6 = LD8(src8++);
 189                                 tmp7 = LD8(src8++);
 190                                 tmp8 = LD8(src8++);
 191
 192                                 tmp0 = __insn_dblalign(tmp0, tmp1, srci);
 193                                 tmp1 = __insn_dblalign(tmp1, tmp2, srci);
 194                                 tmp2 = __insn_dblalign(tmp2, tmp3, srci);
 195                                 tmp3 = __insn_dblalign(tmp3, tmp4, srci);
 196                                 tmp4 = __insn_dblalign(tmp4, tmp5, srci);
 197                                 tmp5 = __insn_dblalign(tmp5, tmp6, srci);
 198                                 tmp6 = __insn_dblalign(tmp6, tmp7, srci);
 199                                 tmp7 = __insn_dblalign(tmp7, tmp8, srci);
 200
 201                                 __insn_wh64(dst8);
 202
 203                                 ST8(dst8++, tmp0);
 204                                 ST8(dst8++, tmp1);
 205                                 ST8(dst8++, tmp2);
 206                                 ST8(dst8++, tmp3);
 207                                 ST8(dst8++, tmp4);
 208                                 ST8(dst8++, tmp5);
 209                                 ST8(dst8++, tmp6);
 210                                 ST8(dst8++, tmp7);
 211
 212                                 tmp0 = tmp8;
 213                         }
 214                         src8--;
 215                 }
 216
 217                 /* Copy the rest 8-byte chunks. */
 218                 if (n >= sizeof(op_t)) {
 219                         tmp0 = LD8(src8++);
 220                         for (; n >= sizeof(op_t); n -= sizeof(op_t)) {
 221                                 tmp1 = LD8(src8++);
 222                                 tmp0 = __insn_dblalign(tmp0, tmp1, srci);
 223                                 ST8(dst8++, tmp0);
 224                                 tmp0 = tmp1;
 225                         }
 226                         src8--;
 227                 }
 228
 229                 if (n == 0)
 230                         return RETVAL;
 231
 232                 tmp0 = LD8(src8++);
 233                 tmp1 = ((const char *)src8 <= src1_end)
 234                         ? LD8((op_t *)src8) : 0;
 235                 final = __insn_dblalign(tmp0, tmp1, srci);
 236
 237         } else {
 238                 /* Aligned copy. */
 239
 240                 const op_t *__restrict src8 = (const op_t *)src1;
 241
 242                 /* src8 and dst8 are both word-aligned. */
 243                 if (n >= CHIP_L2_LINE_SIZE()) {
 244                         /* Copy until 'dst' is cache-line-aligned. */
 245                         for (; (uintptr_t)dst8 & (CHIP_L2_LINE_SIZE() - 1);
 246                              n -= sizeof(op_t))
 247                                 ST8(dst8++, LD8(src8++));
 248
 249                         for (; n >= CHIP_L2_LINE_SIZE(); ) {
 250                                 op_t tmp0, tmp1, tmp2, tmp3;
 251                                 op_t tmp4, tmp5, tmp6, tmp7;
 252
 253                                 /*
 254                                  * Prefetch and advance to next line
 255                                  * to prefetch, but don't go past the
 256                                  * end.
 257                                  */
 258                                 __insn_prefetch(prefetch);
 259
 260                                 /* Make sure prefetch got scheduled
 261                                    earlier.  */
 262                                 __asm__ ("" : : : "memory");
 263
 264                                 prefetch += CHIP_L2_LINE_SIZE();
 265                                 prefetch = (prefetch < src1_end) ? prefetch :
 266                                         (const char *)src8;
 267
 268                                 /*
 269                                  * Do all the loads before wh64.  This
 270                                  * is necessary if [src8, src8+7] and
 271                                  * [dst8, dst8+7] share the same cache
 272                                  * line and dst8 <= src8, as can be
 273                                  * the case when called from memmove,
 274                                  * or with code tested on x86 whose
 275                                  * memcpy always works with forward
 276                                  * copies.
 277                                  */
 278                                 tmp0 = LD8(src8++);
 279                                 tmp1 = LD8(src8++);
 280                                 tmp2 = LD8(src8++);
 281                                 tmp3 = LD8(src8++);
 282                                 tmp4 = LD8(src8++);
 283                                 tmp5 = LD8(src8++);
 284                                 tmp6 = LD8(src8++);
 285                                 tmp7 = LD8(src8++);
 286
 287                                 /* wh64 and wait for tmp7 load completion. */
 288                                 __asm__ ("move %0, %0; wh64 %1\n"
 289                                          : : "r"(tmp7), "r"(dst8));
 290
 291                                 ST8(dst8++, tmp0);
 292                                 ST8(dst8++, tmp1);
 293                                 ST8(dst8++, tmp2);
 294                                 ST8(dst8++, tmp3);
 295                                 ST8(dst8++, tmp4);
 296                                 ST8(dst8++, tmp5);
 297                                 ST8(dst8++, tmp6);
 298                                 ST8(dst8++, tmp7);
 299
 300                                 n -= CHIP_L2_LINE_SIZE();
 301                         }
 302 #if CHIP_L2_LINE_SIZE() != 64
 303 # error "Fix code that assumes particular L2 cache line size."
 304 #endif
 305                 }
 306
 307                 for (; n >= sizeof(op_t); n -= sizeof(op_t))
 308                         ST8(dst8++, LD8(src8++));
 309
 310                 if (__builtin_expect(n == 0, 1))
 311                         return RETVAL;
 312
 313                 final = LD8(src8);
 314         }
 315
 316         /* n != 0 if we get here.  Write out any trailing bytes. */
 317         dst1 = (char *)dst8;
 318 #ifndef __BIG_ENDIAN__
 319         if (n & 4) {
 320                 ST4((uint32_t *)dst1, final);
 321                 dst1 += 4;
 322                 final >>= 32;
 323                 n &= 3;
 324         }
 325         if (n & 2) {
 326                 ST2((uint16_t *)dst1, final);
 327                 dst1 += 2;
 328                 final >>= 16;
 329                 n &= 1;
 330         }
 331         if (n)
 332                 ST1((uint8_t *)dst1, final);
 333 #else
 334         if (n & 4) {
 335                 ST4((uint32_t *)dst1, final >> 32);
 336                 dst1 += 4;
 337         }
 338         else
 339         {
 340                 final >>= 32;
 341         }
 342         if (n & 2) {
 343                 ST2((uint16_t *)dst1, final >> 16);
 344                 dst1 += 2;
 345         }
 346         else
 347         {
 348                 final >>= 16;
 349         }
 350         if (n & 1)
 351                 ST1((uint8_t *)dst1, final >> 8);
 352 #endif
 353
 354         return RETVAL;
 355 }
 356
 357 #ifdef USERCOPY_FUNC
 358 #undef ST1
 359 #undef ST2
 360 #undef ST4
 361 #undef ST8
 362 #undef LD1
 363 #undef LD2
 364 #undef LD4
 365 #undef LD8
 366 #undef USERCOPY_FUNC
 367 #endif