LXR linux/arch/tile/lib/memcpy

   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
  50void *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
  57int __attribute__((optimize("omit-frame-pointer")))
  58USERCOPY_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
 368