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 #define __memcpy memcpy
  19 /* EXPORT_SYMBOL() is in arch/tile/lib/exports.c since this should be asm. */
  20
  21 /* Must be 8 bytes in size. */
  22 #define word_t uint64_t
  23
  24 #if CHIP_L2_LINE_SIZE() != 64 && CHIP_L2_LINE_SIZE() != 128
  25 #error "Assumes 64 or 128 byte line size"
  26 #endif
  27
  28 /* How many cache lines ahead should we prefetch? */
  29 #define PREFETCH_LINES_AHEAD 3
  30
  31 /*
  32  * Provide "base versions" of load and store for the normal code path.
  33  * The kernel provides other versions for userspace copies.
  34  */
  35 #define ST(p, v) (*(p) = (v))
  36 #define LD(p) (*(p))
  37
  38 #ifndef USERCOPY_FUNC
  39 #define ST1 ST
  40 #define ST2 ST
  41 #define ST4 ST
  42 #define ST8 ST
  43 #define LD1 LD
  44 #define LD2 LD
  45 #define LD4 LD
  46 #define LD8 LD
  47 #define RETVAL dstv
  48 void *memcpy(void *__restrict dstv, const void *__restrict srcv, size_t n)
  49 #else
  50 /*
  51  * Special kernel version will provide implementation of the LDn/STn
  52  * macros to return a count of uncopied bytes due to mm fault.
  53  */
  54 #define RETVAL 0
  55 int USERCOPY_FUNC(void *__restrict dstv, const void *__restrict srcv, size_t n)
  56 #endif
  57 {
  58         char *__restrict dst1 = (char *)dstv;
  59         const char *__restrict src1 = (const char *)srcv;
  60         const char *__restrict src1_end;
  61         const char *__restrict prefetch;
  62         word_t *__restrict dst8;    /* 8-byte pointer to destination memory. */
  63         word_t final; /* Final bytes to write to trailing word, if any */
  64         long i;
  65
  66         if (n < 16) {
  67                 for (; n; n--)
  68                         ST1(dst1++, LD1(src1++));
  69                 return RETVAL;
  70         }
  71
  72         /*
  73          * Locate the end of source memory we will copy.  Don't
  74          * prefetch past this.
  75          */
  76         src1_end = src1 + n - 1;
  77
  78         /* Prefetch ahead a few cache lines, but not past the end. */
  79         prefetch = src1;
  80         for (i = 0; i < PREFETCH_LINES_AHEAD; i++) {
  81                 __insn_prefetch(prefetch);
  82                 prefetch += CHIP_L2_LINE_SIZE();
  83                 prefetch = (prefetch > src1_end) ? prefetch : src1;
  84         }
  85
  86         /* Copy bytes until dst is word-aligned. */
  87         for (; (uintptr_t)dst1 & (sizeof(word_t) - 1); n--)
  88                 ST1(dst1++, LD1(src1++));
  89
  90         /* 8-byte pointer to destination memory. */
  91         dst8 = (word_t *)dst1;
  92
  93         if (__builtin_expect((uintptr_t)src1 & (sizeof(word_t) - 1), 0)) {
  94                 /*
  95                  * Misaligned copy.  Copy 8 bytes at a time, but don't
  96                  * bother with other fanciness.
  97                  *
  98                  * TODO: Consider prefetching and using wh64 as well.
  99                  */
 100
 101                 /* Create an aligned src8. */
 102                 const word_t *__restrict src8 =
 103                         (const word_t *)((uintptr_t)src1 & -sizeof(word_t));
 104                 word_t b;
 105
 106                 word_t a = LD8(src8++);
 107                 for (; n >= sizeof(word_t); n -= sizeof(word_t)) {
 108                         b = LD8(src8++);
 109                         a = __insn_dblalign(a, b, src1);
 110                         ST8(dst8++, a);
 111                         a = b;
 112                 }
 113
 114                 if (n == 0)
 115                         return RETVAL;
 116
 117                 b = ((const char *)src8 <= src1_end) ? *src8 : 0;
 118
 119                 /*
 120                  * Final source bytes to write to trailing partial
 121                  * word, if any.
 122                  */
 123                 final = __insn_dblalign(a, b, src1);
 124         } else {
 125                 /* Aligned copy. */
 126
 127                 const word_t* __restrict src8 = (const word_t *)src1;
 128
 129                 /* src8 and dst8 are both word-aligned. */
 130                 if (n >= CHIP_L2_LINE_SIZE()) {
 131                         /* Copy until 'dst' is cache-line-aligned. */
 132                         for (; (uintptr_t)dst8 & (CHIP_L2_LINE_SIZE() - 1);
 133                              n -= sizeof(word_t))
 134                                 ST8(dst8++, LD8(src8++));
 135
 136                         for (; n >= CHIP_L2_LINE_SIZE(); ) {
 137                                 __insn_wh64(dst8);
 138
 139                                 /*
 140                                  * Prefetch and advance to next line
 141                                  * to prefetch, but don't go past the end
 142                                  */
 143                                 __insn_prefetch(prefetch);
 144                                 prefetch += CHIP_L2_LINE_SIZE();
 145                                 prefetch = (prefetch > src1_end) ? prefetch :
 146                                         (const char *)src8;
 147
 148                                 /*
 149                                  * Copy an entire cache line.  Manually
 150                                  * unrolled to avoid idiosyncracies of
 151                                  * compiler unrolling.
 152                                  */
 153 #define COPY_WORD(offset) ({ ST8(dst8+offset, LD8(src8+offset)); n -= 8; })
 154                                 COPY_WORD(0);
 155                                 COPY_WORD(1);
 156                                 COPY_WORD(2);
 157                                 COPY_WORD(3);
 158                                 COPY_WORD(4);
 159                                 COPY_WORD(5);
 160                                 COPY_WORD(6);
 161                                 COPY_WORD(7);
 162 #if CHIP_L2_LINE_SIZE() == 128
 163                                 COPY_WORD(8);
 164                                 COPY_WORD(9);
 165                                 COPY_WORD(10);
 166                                 COPY_WORD(11);
 167                                 COPY_WORD(12);
 168                                 COPY_WORD(13);
 169                                 COPY_WORD(14);
 170                                 COPY_WORD(15);
 171 #elif CHIP_L2_LINE_SIZE() != 64
 172 # error Fix code that assumes particular L2 cache line sizes
 173 #endif
 174
 175                                 dst8 += CHIP_L2_LINE_SIZE() / sizeof(word_t);
 176                                 src8 += CHIP_L2_LINE_SIZE() / sizeof(word_t);
 177                         }
 178                 }
 179
 180                 for (; n >= sizeof(word_t); n -= sizeof(word_t))
 181                         ST8(dst8++, LD8(src8++));
 182
 183                 if (__builtin_expect(n == 0, 1))
 184                         return RETVAL;
 185
 186                 final = LD8(src8);
 187         }
 188
 189         /* n != 0 if we get here.  Write out any trailing bytes. */
 190         dst1 = (char *)dst8;
 191         if (n & 4) {
 192                 ST4((uint32_t *)dst1, final);
 193                 dst1 += 4;
 194                 final >>= 32;
 195                 n &= 3;
 196         }
 197         if (n & 2) {
 198                 ST2((uint16_t *)dst1, final);
 199                 dst1 += 2;
 200                 final >>= 16;
 201                 n &= 1;
 202         }
 203         if (n)
 204                 ST1((uint8_t *)dst1, final);
 205
 206         return RETVAL;
 207 }
 208
 209
 210 #ifdef USERCOPY_FUNC
 211 #undef ST1
 212 #undef ST2
 213 #undef ST4
 214 #undef ST8
 215 #undef LD1
 216 #undef LD2
 217 #undef LD4
 218 #undef LD8
 219 #undef USERCOPY_FUNC
 220 #endif