arch/alpha/lib/csum_partial_copy.c

   1 /*
   2  * csum_partial_copy - do IP checksumming and copy
   3  *
   4  * (C) Copyright 1996 Linus Torvalds
   5  * accellerated versions (and 21264 assembly versions ) contributed by
   6  *      Rick Gorton     <rick.gorton@alpha-processor.com>
   7  *
   8  * Don't look at this too closely - you'll go mad. The things
   9  * we do for performance..
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/string.h>
  14 #include <asm/uaccess.h>
  15
  16
  17 #define ldq_u(x,y) \
  18 __asm__ __volatile__("ldq_u %0,%1":"=r" (x):"m" (*(const unsigned long *)(y)))
  19
  20 #define stq_u(x,y) \
  21 __asm__ __volatile__("stq_u %1,%0":"=m" (*(unsigned long *)(y)):"r" (x))
  22
  23 #define extql(x,y,z) \
  24 __asm__ __volatile__("extql %1,%2,%0":"=r" (z):"r" (x),"r" (y))
  25
  26 #define extqh(x,y,z) \
  27 __asm__ __volatile__("extqh %1,%2,%0":"=r" (z):"r" (x),"r" (y))
  28
  29 #define mskql(x,y,z) \
  30 __asm__ __volatile__("mskql %1,%2,%0":"=r" (z):"r" (x),"r" (y))
  31
  32 #define mskqh(x,y,z) \
  33 __asm__ __volatile__("mskqh %1,%2,%0":"=r" (z):"r" (x),"r" (y))
  34
  35 #define insql(x,y,z) \
  36 __asm__ __volatile__("insql %1,%2,%0":"=r" (z):"r" (x),"r" (y))
  37
  38 #define insqh(x,y,z) \
  39 __asm__ __volatile__("insqh %1,%2,%0":"=r" (z):"r" (x),"r" (y))
  40
  41
  42 #define __get_user_u(x,ptr)                             \
  43 ({                                                      \
  44         long __guu_err;                                 \
  45         __asm__ __volatile__(                           \
  46         "1:     ldq_u %0,%2\n"                          \
  47         "2:\n"                                          \
  48         ".section __ex_table,\"a\"\n"                   \
  49         "       .long 1b - .\n"                         \
  50         "       lda %0,2b-1b(%1)\n"                     \
  51         ".previous"                                     \
  52                 : "=r"(x), "=r"(__guu_err)              \
  53                 : "m"(__m(ptr)), "1"(0));               \
  54         __guu_err;                                      \
  55 })
  56
  57 #define __put_user_u(x,ptr)                             \
  58 ({                                                      \
  59         long __puu_err;                                 \
  60         __asm__ __volatile__(                           \
  61         "1:     stq_u %2,%1\n"                          \
  62         "2:\n"                                          \
  63         ".section __ex_table,\"a\"\n"                   \
  64         "       .long 1b - ."                           \
  65         "       lda $31,2b-1b(%0)\n"                    \
  66         ".previous"                                     \
  67                 : "=r"(__puu_err)                       \
  68                 : "m"(__m(addr)), "rJ"(x), "0"(0));     \
  69         __puu_err;                                      \
  70 })
  71
  72
  73 static inline unsigned short from64to16(unsigned long x)
  74 {
  75         /* Using extract instructions is a bit more efficient
  76            than the original shift/bitmask version.  */
  77
  78         union {
  79                 unsigned long   ul;
  80                 unsigned int    ui[2];
  81                 unsigned short  us[4];
  82         } in_v, tmp_v, out_v;
  83
  84         in_v.ul = x;
  85         tmp_v.ul = (unsigned long) in_v.ui[0] + (unsigned long) in_v.ui[1];
  86
  87         /* Since the bits of tmp_v.sh[3] are going to always be zero,
  88            we don't have to bother to add that in.  */
  89         out_v.ul = (unsigned long) tmp_v.us[0] + (unsigned long) tmp_v.us[1]
  90                         + (unsigned long) tmp_v.us[2];
  91
  92         /* Similarly, out_v.us[2] is always zero for the final add.  */
  93         return out_v.us[0] + out_v.us[1];
  94 }
  95
  96
  97
  98 /*
  99  * Ok. This isn't fun, but this is the EASY case.
 100  */
 101 static inline unsigned long
 102 csum_partial_cfu_aligned(const unsigned long *src, unsigned long *dst,
 103                          long len, unsigned long checksum,
 104                          int *errp)
 105 {
 106         unsigned long carry = 0;
 107         int err = 0;
 108
 109         while (len >= 0) {
 110                 unsigned long word;
 111                 err |= __get_user(word, src);
 112                 checksum += carry;
 113                 src++;
 114                 checksum += word;
 115                 len -= 8;
 116                 carry = checksum < word;
 117                 *dst = word;
 118                 dst++;
 119         }
 120         len += 8;
 121         checksum += carry;
 122         if (len) {
 123                 unsigned long word, tmp;
 124                 err |= __get_user(word, src);
 125                 tmp = *dst;
 126                 mskql(word, len, word);
 127                 checksum += word;
 128                 mskqh(tmp, len, tmp);
 129                 carry = checksum < word;
 130                 *dst = word | tmp;
 131                 checksum += carry;
 132         }
 133         if (err) *errp = err;
 134         return checksum;
 135 }
 136
 137 /*
 138  * This is even less fun, but this is still reasonably
 139  * easy.
 140  */
 141 static inline unsigned long
 142 csum_partial_cfu_dest_aligned(const unsigned long *src, unsigned long *dst,
 143                               unsigned long soff,
 144                               long len, unsigned long checksum,
 145                               int *errp)
 146 {
 147         unsigned long first;
 148         unsigned long word, carry;
 149         unsigned long lastsrc = 7+len+(unsigned long)src;
 150         int err = 0;
 151
 152         err |= __get_user_u(first,src);
 153         carry = 0;
 154         while (len >= 0) {
 155                 unsigned long second;
 156
 157                 err |= __get_user_u(second, src+1);
 158                 extql(first, soff, word);
 159                 len -= 8;
 160                 src++;
 161                 extqh(second, soff, first);
 162                 checksum += carry;
 163                 word |= first;
 164                 first = second;
 165                 checksum += word;
 166                 *dst = word;
 167                 dst++;
 168                 carry = checksum < word;
 169         }
 170         len += 8;
 171         checksum += carry;
 172         if (len) {
 173                 unsigned long tmp;
 174                 unsigned long second;
 175                 err |= __get_user_u(second, lastsrc);
 176                 tmp = *dst;
 177                 extql(first, soff, word);
 178                 extqh(second, soff, first);
 179                 word |= first;
 180                 mskql(word, len, word);
 181                 checksum += word;
 182                 mskqh(tmp, len, tmp);
 183                 carry = checksum < word;
 184                 *dst = word | tmp;
 185                 checksum += carry;
 186         }
 187         if (err) *errp = err;
 188         return checksum;
 189 }
 190
 191 /*
 192  * This is slightly less fun than the above..
 193  */
 194 static inline unsigned long
 195 csum_partial_cfu_src_aligned(const unsigned long *src, unsigned long *dst,
 196                              unsigned long doff,
 197                              long len, unsigned long checksum,
 198                              unsigned long partial_dest,
 199                              int *errp)
 200 {
 201         unsigned long carry = 0;
 202         unsigned long word;
 203         unsigned long second_dest;
 204         int err = 0;
 205
 206         mskql(partial_dest, doff, partial_dest);
 207         while (len >= 0) {
 208                 err |= __get_user(word, src);
 209                 len -= 8;
 210                 insql(word, doff, second_dest);
 211                 checksum += carry;
 212                 stq_u(partial_dest | second_dest, dst);
 213                 src++;
 214                 checksum += word;
 215                 insqh(word, doff, partial_dest);
 216                 carry = checksum < word;
 217                 dst++;
 218         }
 219         len += 8;
 220         if (len) {
 221                 checksum += carry;
 222                 err |= __get_user(word, src);
 223                 mskql(word, len, word);
 224                 len -= 8;
 225                 checksum += word;
 226                 insql(word, doff, second_dest);
 227                 len += doff;
 228                 carry = checksum < word;
 229                 partial_dest |= second_dest;
 230                 if (len >= 0) {
 231                         stq_u(partial_dest, dst);
 232                         if (!len) goto out;
 233                         dst++;
 234                         insqh(word, doff, partial_dest);
 235                 }
 236                 doff = len;
 237         }
 238         ldq_u(second_dest, dst);
 239         mskqh(second_dest, doff, second_dest);
 240         stq_u(partial_dest | second_dest, dst);
 241 out:
 242         checksum += carry;
 243         if (err) *errp = err;
 244         return checksum;
 245 }
 246
 247 /*
 248  * This is so totally un-fun that it's frightening. Don't
 249  * look at this too closely, you'll go blind.
 250  */
 251 static inline unsigned long
 252 csum_partial_cfu_unaligned(const unsigned long * src, unsigned long * dst,
 253                            unsigned long soff, unsigned long doff,
 254                            long len, unsigned long checksum,
 255                            unsigned long partial_dest,
 256                            int *errp)
 257 {
 258         unsigned long carry = 0;
 259         unsigned long first;
 260         unsigned long lastsrc;
 261         int err = 0;
 262
 263         err |= __get_user_u(first, src);
 264         lastsrc = 7+len+(unsigned long)src;
 265         mskql(partial_dest, doff, partial_dest);
 266         while (len >= 0) {
 267                 unsigned long second, word;
 268                 unsigned long second_dest;
 269
 270                 err |= __get_user_u(second, src+1);
 271                 extql(first, soff, word);
 272                 checksum += carry;
 273                 len -= 8;
 274                 extqh(second, soff, first);
 275                 src++;
 276                 word |= first;
 277                 first = second;
 278                 insql(word, doff, second_dest);
 279                 checksum += word;
 280                 stq_u(partial_dest | second_dest, dst);
 281                 carry = checksum < word;
 282                 insqh(word, doff, partial_dest);
 283                 dst++;
 284         }
 285         len += doff;
 286         checksum += carry;
 287         if (len >= 0) {
 288                 unsigned long second, word;
 289                 unsigned long second_dest;
 290
 291                 err |= __get_user_u(second, lastsrc);
 292                 extql(first, soff, word);
 293                 extqh(second, soff, first);
 294                 word |= first;
 295                 first = second;
 296                 mskql(word, len-doff, word);
 297                 checksum += word;
 298                 insql(word, doff, second_dest);
 299                 carry = checksum < word;
 300                 stq_u(partial_dest | second_dest, dst);
 301                 if (len) {
 302                         ldq_u(second_dest, dst+1);
 303                         insqh(word, doff, partial_dest);
 304                         mskqh(second_dest, len, second_dest);
 305                         stq_u(partial_dest | second_dest, dst+1);
 306                 }
 307                 checksum += carry;
 308         } else {
 309                 unsigned long second, word;
 310                 unsigned long second_dest;
 311
 312                 err |= __get_user_u(second, lastsrc);
 313                 extql(first, soff, word);
 314                 extqh(second, soff, first);
 315                 word |= first;
 316                 ldq_u(second_dest, dst);
 317                 mskql(word, len-doff, word);
 318                 checksum += word;
 319                 mskqh(second_dest, len, second_dest);
 320                 carry = checksum < word;
 321                 insql(word, doff, word);
 322                 stq_u(partial_dest | word | second_dest, dst);
 323                 checksum += carry;
 324         }
 325         if (err) *errp = err;
 326         return checksum;
 327 }
 328
 329 static unsigned int
 330 do_csum_partial_copy_from_user(const char *src, char *dst, int len,
 331                                unsigned int sum, int *errp)
 332 {
 333         unsigned long checksum = (unsigned) sum;
 334         unsigned long soff = 7 & (unsigned long) src;
 335         unsigned long doff = 7 & (unsigned long) dst;
 336
 337         if (len) {
 338                 if (!doff) {
 339                         if (!soff)
 340                                 checksum = csum_partial_cfu_aligned(
 341                                         (const unsigned long *) src,
 342                                         (unsigned long *) dst,
 343                                         len-8, checksum, errp);
 344                         else
 345                                 checksum = csum_partial_cfu_dest_aligned(
 346                                         (const unsigned long *) src,
 347                                         (unsigned long *) dst,
 348                                         soff, len-8, checksum, errp);
 349                 } else {
 350                         unsigned long partial_dest;
 351                         ldq_u(partial_dest, dst);
 352                         if (!soff)
 353                                 checksum = csum_partial_cfu_src_aligned(
 354                                         (const unsigned long *) src,
 355                                         (unsigned long *) dst,
 356                                         doff, len-8, checksum,
 357                                         partial_dest, errp);
 358                         else
 359                                 checksum = csum_partial_cfu_unaligned(
 360                                         (const unsigned long *) src,
 361                                         (unsigned long *) dst,
 362                                         soff, doff, len-8, checksum,
 363                                         partial_dest, errp);
 364                 }
 365                 checksum = from64to16 (checksum);
 366         }
 367         return checksum;
 368 }
 369
 370 unsigned int
 371 csum_partial_copy_from_user(const char *src, char *dst, int len,
 372                             unsigned int sum, int *errp)
 373 {
 374         if (!access_ok(src, len, VERIFY_READ)) {
 375                 *errp = -EFAULT;
 376                 memset(dst, 0, len);
 377                 return sum;
 378         }
 379
 380         return do_csum_partial_copy_from_user(src, dst, len, sum, errp);
 381 }
 382
 383 unsigned int
 384 csum_partial_copy_nocheck(const char *src, char *dst, int len, unsigned int sum)
 385 {
 386         return do_csum_partial_copy_from_user(src, dst, len, sum, NULL);
 387 }