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 word_t uint64_t
  22
  23 #if CHIP_L2_LINE_SIZE() != 64 && CHIP_L2_LINE_SIZE() != 128
  24 #error "Assumes 64 or 128 byte line size"
  25 #endif
  26
  27 /* How many cache lines ahead should we prefetch? */
  28 #define PREFETCH_LINES_AHEAD 3
  29
  30 /*
  31  * Provide "base versions" of load and store for the normal code path.
  32  * The kernel provides other versions for userspace copies.
  33  */
  34 #define ST(p, v) (*(p) = (v))
  35 #define LD(p) (*(p))
  36
  37 #ifndef USERCOPY_FUNC
  38 #define ST1 ST
  39 #define ST2 ST
  40 #define ST4 ST
  41 #define ST8 ST
  42 #define LD1 LD
  43 #define LD2 LD
  44 #define LD4 LD
  45 #define LD8 LD
  46 #define RETVAL dstv
  47 void *memcpy(void *__restrict dstv, const void *__restrict srcv, size_t n)
  48 #else
  49 /*
  50  * Special kernel version will provide implementation of the LDn/STn
  51  * macros to return a count of uncopied bytes due to mm fault.
  52  */
  53 #define RETVAL 0
  54 int USERCOPY_FUNC(void *__restrict dstv, const void *__restrict srcv, size_t n)
  55 #endif
  56 {
  57         char *__restrict dst1 = (char *)dstv;
  58         const char *__restrict src1 = (const char *)srcv;
  59         const char *__restrict src1_end;
  60         const char *__restrict prefetch;
  61         word_t *__restrict dst8;    /* 8-byte pointer to destination memory. */
  62         word_t final; /* Final bytes to write to trailing word, if any */
  63         long i;
  64
  65         if (n < 16) {
  66                 for (; n; n--)
  67                         ST1(dst1++, LD1(src1++));
  68                 return RETVAL;
  69         }
  70
  71         /*
  72          * Locate the end of source memory we will copy.  Don't
  73          * prefetch past this.
  74          */
  75         src1_end = src1 + n - 1;
  76
  77         /* Prefetch ahead a few cache lines, but not past the end. */
  78         prefetch = src1;
  79         for (i = 0; i < PREFETCH_LINES_AHEAD; i++) {
  80                 __insn_prefetch(prefetch);
  81                 prefetch += CHIP_L2_LINE_SIZE();
  82                 prefetch = (prefetch > src1_end) ? prefetch : src1;
  83         }
  84
  85         /* Copy bytes until dst is word-aligned. */
  86         for (; (uintptr_t)dst1 & (sizeof(word_t) - 1); n--)
  87                 ST1(dst1++, LD1(src1++));
  88
  89         /* 8-byte pointer to destination memory. */
  90         dst8 = (word_t *)dst1;
  91
  92         if (__builtin_expect((uintptr_t)src1 & (sizeof(word_t) - 1), 0)) {
  93                 /*
  94                  * Misaligned copy.  Copy 8 bytes at a time, but don't
  95                  * bother with other fanciness.
  96                  *
  97                  * TODO: Consider prefetching and using wh64 as well.
  98                  */
  99
 100                 /* Create an aligned src8. */
 101                 const word_t *__restrict src8 =
 102                         (const word_t *)((uintptr_t)src1 & -sizeof(word_t));
 103                 word_t b;
 104
 105                 word_t a = LD8(src8++);
 106                 for (; n >= sizeof(word_t); n -= sizeof(word_t)) {
 107                         b = LD8(src8++);
 108                         a = __insn_dblalign(a, b, src1);
 109                         ST8(dst8++, a);
 110                         a = b;
 111                 }
 112
 113                 if (n == 0)
 114                         return RETVAL;
 115
 116                 b = ((const char *)src8 <= src1_end) ? *src8 : 0;
 117
 118                 /*
 119                  * Final source bytes to write to trailing partial
 120                  * word, if any.
 121                  */
 122                 final = __insn_dblalign(a, b, src1);
 123         } else {
 124                 /* Aligned copy. */
 125
 126                 const word_t* __restrict src8 = (const word_t *)src1;
 127
 128                 /* src8 and dst8 are both word-aligned. */
 129                 if (n >= CHIP_L2_LINE_SIZE()) {
 130                         /* Copy until 'dst' is cache-line-aligned. */
 131                         for (; (uintptr_t)dst8 & (CHIP_L2_LINE_SIZE() - 1);
 132                              n -= sizeof(word_t))
 133                                 ST8(dst8++, LD8(src8++));
 134
 135                         for (; n >= CHIP_L2_LINE_SIZE(); ) {
 136                                 __insn_wh64(dst8);
 137
 138                                 /*
 139                                  * Prefetch and advance to next line
 140                                  * to prefetch, but don't go past the end
 141                                  */
 142                                 __insn_prefetch(prefetch);
 143                                 prefetch += CHIP_L2_LINE_SIZE();
 144                                 prefetch = (prefetch > src1_end) ? prefetch :
 145                                         (const char *)src8;
 146
 147                                 /*
 148                                  * Copy an entire cache line.  Manually
 149                                  * unrolled to avoid idiosyncracies of
 150                                  * compiler unrolling.
 151                                  */
 152 #define COPY_WORD(offset) ({ ST8(dst8+offset, LD8(src8+offset)); n -= 8; })
 153                                 COPY_WORD(0);
 154                                 COPY_WORD(1);
 155                                 COPY_WORD(2);
 156                                 COPY_WORD(3);
 157                                 COPY_WORD(4);
 158                                 COPY_WORD(5);
 159                                 COPY_WORD(6);
 160                                 COPY_WORD(7);
 161 #if CHIP_L2_LINE_SIZE() == 128
 162                                 COPY_WORD(8);
 163                                 COPY_WORD(9);
 164                                 COPY_WORD(10);
 165                                 COPY_WORD(11);
 166                                 COPY_WORD(12);
 167                                 COPY_WORD(13);
 168                                 COPY_WORD(14);
 169                                 COPY_WORD(15);
 170 #elif CHIP_L2_LINE_SIZE() != 64
 171 # error Fix code that assumes particular L2 cache line sizes
 172 #endif
 173
 174                                 dst8 += CHIP_L2_LINE_SIZE() / sizeof(word_t);
 175                                 src8 += CHIP_L2_LINE_SIZE() / sizeof(word_t);
 176                         }
 177                 }
 178
 179                 for (; n >= sizeof(word_t); n -= sizeof(word_t))
 180                         ST8(dst8++, LD8(src8++));
 181
 182                 if (__builtin_expect(n == 0, 1))
 183                         return RETVAL;
 184
 185                 final = LD8(src8);
 186         }
 187
 188         /* n != 0 if we get here.  Write out any trailing bytes. */
 189         dst1 = (char *)dst8;
 190 #ifndef __BIG_ENDIAN__
 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 #else
 206         if (n & 4) {
 207                 ST4((uint32_t *)dst1, final >> 32);
 208                 dst1 += 4;
 209         }
 210         else
 211         {
 212                 final >>= 32;
 213         }
 214         if (n & 2) {
 215                 ST2((uint16_t *)dst1, final >> 16);
 216                 dst1 += 2;
 217         }
 218         else
 219         {
 220                 final >>= 16;
 221         }
 222         if (n & 1)
 223                 ST1((uint8_t *)dst1, final >> 8);
 224 #endif
 225
 226         return RETVAL;
 227 }
 228
 229 #ifdef USERCOPY_FUNC
 230 #undef ST1
 231 #undef ST2
 232 #undef ST4
 233 #undef ST8
 234 #undef LD1
 235 #undef LD2
 236 #undef LD4
 237 #undef LD8
 238 #undef USERCOPY_FUNC
 239 #endif