arch/m68k/lib/checksum.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              IP/TCP/UDP checksumming routines
   7  *
   8  * Authors:     Jorge Cwik, <jorge@laser.satlink.net>
   9  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  10  *              Tom May, <ftom@netcom.com>
  11  *              Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de>
  12  *              Lots of code moved from tcp.c and ip.c; see those files
  13  *              for more names.
  14  *
  15  * 03/02/96     Jes Sorensen, Andreas Schwab, Roman Hodek:
  16  *              Fixed some nasty bugs, causing some horrible crashes.
  17  *              A: At some points, the sum (%0) was used as
  18  *              length-counter instead of the length counter
  19  *              (%1). Thanks to Roman Hodek for pointing this out.
  20  *              B: GCC seems to mess up if one uses too many
  21  *              data-registers to hold input values and one tries to
  22  *              specify d0 and d1 as scratch registers. Letting gcc
  23  *              choose these registers itself solves the problem.
  24  *
  25  *              This program is free software; you can redistribute it and/or
  26  *              modify it under the terms of the GNU General Public License
  27  *              as published by the Free Software Foundation; either version
  28  *              2 of the License, or (at your option) any later version.
  29  *
  30  * 1998/8/31    Andreas Schwab:
  31  *              Zero out rest of buffer on exception in
  32  *              csum_partial_copy_from_user.
  33  */
  34
  35 #include <linux/module.h>
  36 #include <net/checksum.h>
  37
  38 #ifdef CONFIG_COLDFIRE
  39
  40 static inline unsigned short from32to16(unsigned long x)
  41 {
  42         /* add up 16-bit and 16-bit for 16+c bit */
  43         x = (x & 0xffff) + (x >> 16);
  44         /* add up carry.. */
  45         x = (x & 0xffff) + (x >> 16);
  46         return x;
  47 }
  48
  49 static unsigned long do_csum(const unsigned char *buff, int len)
  50 {
  51         int odd, count;
  52         unsigned long result = 0;
  53
  54         if (len <= 0)
  55                 goto out;
  56         odd = 1 & (unsigned long) buff;
  57         if (odd) {
  58                 result = *buff;
  59                 len--;
  60                 buff++;
  61         }
  62         count = len >> 1;               /* nr of 16-bit words.. */
  63         if (count) {
  64                 if (2 & (unsigned long) buff) {
  65                         result += *(unsigned short *) buff;
  66                         count--;
  67                         len -= 2;
  68                         buff += 2;
  69                 }
  70                 count >>= 1;            /* nr of 32-bit words.. */
  71                 if (count) {
  72                         unsigned long carry = 0;
  73                         do {
  74                                 unsigned long w = *(unsigned long *) buff;
  75                                 count--;
  76                                 buff += 4;
  77                                 result += carry;
  78                                 result += w;
  79                                 carry = (w > result);
  80                         } while (count);
  81                         result += carry;
  82                         result = (result & 0xffff) + (result >> 16);
  83                 }
  84                 if (len & 2) {
  85                         result += *(unsigned short *) buff;
  86                         buff += 2;
  87                 }
  88         }
  89         if (len & 1)
  90                 result += (*buff << 8);
  91         result = from32to16(result);
  92         if (odd)
  93                 result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
  94 out:
  95         return result;
  96 }
  97
  98 /*
  99  * computes the checksum of a memory block at buff, length len,
 100  * and adds in "sum" (32-bit)
 101  *
 102  * returns a 32-bit number suitable for feeding into itself
 103  * or csum_tcpudp_magic
 104  *
 105  * this function must be called with even lengths, except
 106  * for the last fragment, which may be odd
 107  *
 108  * it's best to have buff aligned on a 32-bit boundary
 109  */
 110 __wsum csum_partial(const void *buff, int len, __wsum sum)
 111 {
 112         unsigned int result = do_csum(buff, len);
 113
 114         /* add in old sum, and carry.. */
 115         result += sum;
 116         if (sum > result)
 117                 result += 1;
 118         return result;
 119 }
 120 EXPORT_SYMBOL(csum_partial);
 121
 122 /*
 123  * copy from fs while checksumming, otherwise like csum_partial
 124  */
 125
 126 __wsum
 127 csum_partial_copy_from_user(const void __user *src, void *dst, int len,
 128                             __wsum sum, int *csum_err)
 129 {
 130         if (csum_err) *csum_err = 0;
 131         memcpy(dst, src, len);
 132         return csum_partial(dst, len, sum);
 133 }
 134 EXPORT_SYMBOL(csum_partial_copy_from_user);
 135
 136 /*
 137  * copy from ds while checksumming, otherwise like csum_partial
 138  */
 139
 140 __wsum
 141 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
 142 {
 143         memcpy(dst, src, len);
 144         return csum_partial(dst, len, sum);
 145 }
 146 EXPORT_SYMBOL(csum_partial_copy_nocheck);
 147
 148 #else /* !CONFIG_COLDFIRE */
 149
 150 /*
 151  * computes a partial checksum, e.g. for TCP/UDP fragments
 152  */
 153
 154 __wsum csum_partial(const void *buff, int len, __wsum sum)
 155 {
 156         unsigned long tmp1, tmp2;
 157           /*
 158            * Experiments with ethernet and slip connections show that buff
 159            * is aligned on either a 2-byte or 4-byte boundary.
 160            */
 161         __asm__("movel %2,%3\n\t"
 162                 "btst #1,%3\n\t"        /* Check alignment */
 163                 "jeq 2f\n\t"
 164                 "subql #2,%1\n\t"       /* buff%4==2: treat first word */
 165                 "jgt 1f\n\t"
 166                 "addql #2,%1\n\t"       /* len was == 2, treat only rest */
 167                 "jra 4f\n"
 168              "1:\t"
 169                 "addw %2@+,%0\n\t"      /* add first word to sum */
 170                 "clrl %3\n\t"
 171                 "addxl %3,%0\n"         /* add X bit */
 172              "2:\t"
 173                 /* unrolled loop for the main part: do 8 longs at once */
 174                 "movel %1,%3\n\t"       /* save len in tmp1 */
 175                 "lsrl #5,%1\n\t"        /* len/32 */
 176                 "jeq 2f\n\t"            /* not enough... */
 177                 "subql #1,%1\n"
 178              "1:\t"
 179                 "movel %2@+,%4\n\t"
 180                 "addxl %4,%0\n\t"
 181                 "movel %2@+,%4\n\t"
 182                 "addxl %4,%0\n\t"
 183                 "movel %2@+,%4\n\t"
 184                 "addxl %4,%0\n\t"
 185                 "movel %2@+,%4\n\t"
 186                 "addxl %4,%0\n\t"
 187                 "movel %2@+,%4\n\t"
 188                 "addxl %4,%0\n\t"
 189                 "movel %2@+,%4\n\t"
 190                 "addxl %4,%0\n\t"
 191                 "movel %2@+,%4\n\t"
 192                 "addxl %4,%0\n\t"
 193                 "movel %2@+,%4\n\t"
 194                 "addxl %4,%0\n\t"
 195                 "dbra %1,1b\n\t"
 196                 "clrl %4\n\t"
 197                 "addxl %4,%0\n\t"       /* add X bit */
 198                 "clrw %1\n\t"
 199                 "subql #1,%1\n\t"
 200                 "jcc 1b\n"
 201              "2:\t"
 202                 "movel %3,%1\n\t"       /* restore len from tmp1 */
 203                 "andw #0x1c,%3\n\t"     /* number of rest longs */
 204                 "jeq 4f\n\t"
 205                 "lsrw #2,%3\n\t"
 206                 "subqw #1,%3\n"
 207              "3:\t"
 208                 /* loop for rest longs */
 209                 "movel %2@+,%4\n\t"
 210                 "addxl %4,%0\n\t"
 211                 "dbra %3,3b\n\t"
 212                 "clrl %4\n\t"
 213                 "addxl %4,%0\n"         /* add X bit */
 214              "4:\t"
 215                 /* now check for rest bytes that do not fit into longs */
 216                 "andw #3,%1\n\t"
 217                 "jeq 7f\n\t"
 218                 "clrl %4\n\t"           /* clear tmp2 for rest bytes */
 219                 "subqw #2,%1\n\t"
 220                 "jlt 5f\n\t"
 221                 "movew %2@+,%4\n\t"     /* have rest >= 2: get word */
 222                 "swap %4\n\t"           /* into bits 16..31 */
 223                 "tstw %1\n\t"           /* another byte? */
 224                 "jeq 6f\n"
 225              "5:\t"
 226                 "moveb %2@,%4\n\t"      /* have odd rest: get byte */
 227                 "lslw #8,%4\n\t"        /* into bits 8..15; 16..31 untouched */
 228              "6:\t"
 229                 "addl %4,%0\n\t"        /* now add rest long to sum */
 230                 "clrl %4\n\t"
 231                 "addxl %4,%0\n"         /* add X bit */
 232              "7:\t"
 233                 : "=d" (sum), "=d" (len), "=a" (buff),
 234                   "=&d" (tmp1), "=&d" (tmp2)
 235                 : "0" (sum), "1" (len), "2" (buff)
 236             );
 237         return(sum);
 238 }
 239
 240 EXPORT_SYMBOL(csum_partial);
 241
 242
 243 /*
 244  * copy from user space while checksumming, with exception handling.
 245  */
 246
 247 __wsum
 248 csum_partial_copy_from_user(const void __user *src, void *dst,
 249                             int len, __wsum sum, int *csum_err)
 250 {
 251         /*
 252          * GCC doesn't like more than 10 operands for the asm
 253          * statements so we have to use tmp2 for the error
 254          * code.
 255          */
 256         unsigned long tmp1, tmp2;
 257
 258         __asm__("movel %2,%4\n\t"
 259                 "btst #1,%4\n\t"        /* Check alignment */
 260                 "jeq 2f\n\t"
 261                 "subql #2,%1\n\t"       /* buff%4==2: treat first word */
 262                 "jgt 1f\n\t"
 263                 "addql #2,%1\n\t"       /* len was == 2, treat only rest */
 264                 "jra 4f\n"
 265              "1:\n"
 266              "10:\t"
 267                 "movesw %2@+,%4\n\t"    /* add first word to sum */
 268                 "addw %4,%0\n\t"
 269                 "movew %4,%3@+\n\t"
 270                 "clrl %4\n\t"
 271                 "addxl %4,%0\n"         /* add X bit */
 272              "2:\t"
 273                 /* unrolled loop for the main part: do 8 longs at once */
 274                 "movel %1,%4\n\t"       /* save len in tmp1 */
 275                 "lsrl #5,%1\n\t"        /* len/32 */
 276                 "jeq 2f\n\t"            /* not enough... */
 277                 "subql #1,%1\n"
 278              "1:\n"
 279              "11:\t"
 280                 "movesl %2@+,%5\n\t"
 281                 "addxl %5,%0\n\t"
 282                 "movel %5,%3@+\n\t"
 283              "12:\t"
 284                 "movesl %2@+,%5\n\t"
 285                 "addxl %5,%0\n\t"
 286                 "movel %5,%3@+\n\t"
 287              "13:\t"
 288                 "movesl %2@+,%5\n\t"
 289                 "addxl %5,%0\n\t"
 290                 "movel %5,%3@+\n\t"
 291              "14:\t"
 292                 "movesl %2@+,%5\n\t"
 293                 "addxl %5,%0\n\t"
 294                 "movel %5,%3@+\n\t"
 295              "15:\t"
 296                 "movesl %2@+,%5\n\t"
 297                 "addxl %5,%0\n\t"
 298                 "movel %5,%3@+\n\t"
 299              "16:\t"
 300                 "movesl %2@+,%5\n\t"
 301                 "addxl %5,%0\n\t"
 302                 "movel %5,%3@+\n\t"
 303              "17:\t"
 304                 "movesl %2@+,%5\n\t"
 305                 "addxl %5,%0\n\t"
 306                 "movel %5,%3@+\n\t"
 307              "18:\t"
 308                 "movesl %2@+,%5\n\t"
 309                 "addxl %5,%0\n\t"
 310                 "movel %5,%3@+\n\t"
 311                 "dbra %1,1b\n\t"
 312                 "clrl %5\n\t"
 313                 "addxl %5,%0\n\t"       /* add X bit */
 314                 "clrw %1\n\t"
 315                 "subql #1,%1\n\t"
 316                 "jcc 1b\n"
 317              "2:\t"
 318                 "movel %4,%1\n\t"       /* restore len from tmp1 */
 319                 "andw #0x1c,%4\n\t"     /* number of rest longs */
 320                 "jeq 4f\n\t"
 321                 "lsrw #2,%4\n\t"
 322                 "subqw #1,%4\n"
 323              "3:\n"
 324                 /* loop for rest longs */
 325              "19:\t"
 326                 "movesl %2@+,%5\n\t"
 327                 "addxl %5,%0\n\t"
 328                 "movel %5,%3@+\n\t"
 329                 "dbra %4,3b\n\t"
 330                 "clrl %5\n\t"
 331                 "addxl %5,%0\n"         /* add X bit */
 332              "4:\t"
 333                 /* now check for rest bytes that do not fit into longs */
 334                 "andw #3,%1\n\t"
 335                 "jeq 7f\n\t"
 336                 "clrl %5\n\t"           /* clear tmp2 for rest bytes */
 337                 "subqw #2,%1\n\t"
 338                 "jlt 5f\n\t"
 339              "20:\t"
 340                 "movesw %2@+,%5\n\t"    /* have rest >= 2: get word */
 341                 "movew %5,%3@+\n\t"
 342                 "swap %5\n\t"           /* into bits 16..31 */
 343                 "tstw %1\n\t"           /* another byte? */
 344                 "jeq 6f\n"
 345              "5:\n"
 346              "21:\t"
 347                 "movesb %2@,%5\n\t"     /* have odd rest: get byte */
 348                 "moveb %5,%3@+\n\t"
 349                 "lslw #8,%5\n\t"        /* into bits 8..15; 16..31 untouched */
 350              "6:\t"
 351                 "addl %5,%0\n\t"        /* now add rest long to sum */
 352                 "clrl %5\n\t"
 353                 "addxl %5,%0\n\t"       /* add X bit */
 354              "7:\t"
 355                 "clrl %5\n"             /* no error - clear return value */
 356              "8:\n"
 357                 ".section .fixup,\"ax\"\n"
 358                 ".even\n"
 359                 /* If any exception occurs zero out the rest.
 360                    Similarities with the code above are intentional :-) */
 361              "90:\t"
 362                 "clrw %3@+\n\t"
 363                 "movel %1,%4\n\t"
 364                 "lsrl #5,%1\n\t"
 365                 "jeq 1f\n\t"
 366                 "subql #1,%1\n"
 367              "91:\t"
 368                 "clrl %3@+\n"
 369              "92:\t"
 370                 "clrl %3@+\n"
 371              "93:\t"
 372                 "clrl %3@+\n"
 373              "94:\t"
 374                 "clrl %3@+\n"
 375              "95:\t"
 376                 "clrl %3@+\n"
 377              "96:\t"
 378                 "clrl %3@+\n"
 379              "97:\t"
 380                 "clrl %3@+\n"
 381              "98:\t"
 382                 "clrl %3@+\n\t"
 383                 "dbra %1,91b\n\t"
 384                 "clrw %1\n\t"
 385                 "subql #1,%1\n\t"
 386                 "jcc 91b\n"
 387              "1:\t"
 388                 "movel %4,%1\n\t"
 389                 "andw #0x1c,%4\n\t"
 390                 "jeq 1f\n\t"
 391                 "lsrw #2,%4\n\t"
 392                 "subqw #1,%4\n"
 393              "99:\t"
 394                 "clrl %3@+\n\t"
 395                 "dbra %4,99b\n\t"
 396              "1:\t"
 397                 "andw #3,%1\n\t"
 398                 "jeq 9f\n"
 399              "100:\t"
 400                 "clrw %3@+\n\t"
 401                 "tstw %1\n\t"
 402                 "jeq 9f\n"
 403              "101:\t"
 404                 "clrb %3@+\n"
 405              "9:\t"
 406 #define STR(X) STR1(X)
 407 #define STR1(X) #X
 408                 "moveq #-" STR(EFAULT) ",%5\n\t"
 409                 "jra 8b\n"
 410                 ".previous\n"
 411                 ".section __ex_table,\"a\"\n"
 412                 ".long 10b,90b\n"
 413                 ".long 11b,91b\n"
 414                 ".long 12b,92b\n"
 415                 ".long 13b,93b\n"
 416                 ".long 14b,94b\n"
 417                 ".long 15b,95b\n"
 418                 ".long 16b,96b\n"
 419                 ".long 17b,97b\n"
 420                 ".long 18b,98b\n"
 421                 ".long 19b,99b\n"
 422                 ".long 20b,100b\n"
 423                 ".long 21b,101b\n"
 424                 ".previous"
 425                 : "=d" (sum), "=d" (len), "=a" (src), "=a" (dst),
 426                   "=&d" (tmp1), "=d" (tmp2)
 427                 : "0" (sum), "1" (len), "2" (src), "3" (dst)
 428             );
 429
 430         *csum_err = tmp2;
 431
 432         return(sum);
 433 }
 434
 435 EXPORT_SYMBOL(csum_partial_copy_from_user);
 436
 437
 438 /*
 439  * copy from kernel space while checksumming, otherwise like csum_partial
 440  */
 441
 442 __wsum
 443 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
 444 {
 445         unsigned long tmp1, tmp2;
 446         __asm__("movel %2,%4\n\t"
 447                 "btst #1,%4\n\t"        /* Check alignment */
 448                 "jeq 2f\n\t"
 449                 "subql #2,%1\n\t"       /* buff%4==2: treat first word */
 450                 "jgt 1f\n\t"
 451                 "addql #2,%1\n\t"       /* len was == 2, treat only rest */
 452                 "jra 4f\n"
 453              "1:\t"
 454                 "movew %2@+,%4\n\t"     /* add first word to sum */
 455                 "addw %4,%0\n\t"
 456                 "movew %4,%3@+\n\t"
 457                 "clrl %4\n\t"
 458                 "addxl %4,%0\n"         /* add X bit */
 459              "2:\t"
 460                 /* unrolled loop for the main part: do 8 longs at once */
 461                 "movel %1,%4\n\t"       /* save len in tmp1 */
 462                 "lsrl #5,%1\n\t"        /* len/32 */
 463                 "jeq 2f\n\t"            /* not enough... */
 464                 "subql #1,%1\n"
 465              "1:\t"
 466                 "movel %2@+,%5\n\t"
 467                 "addxl %5,%0\n\t"
 468                 "movel %5,%3@+\n\t"
 469                 "movel %2@+,%5\n\t"
 470                 "addxl %5,%0\n\t"
 471                 "movel %5,%3@+\n\t"
 472                 "movel %2@+,%5\n\t"
 473                 "addxl %5,%0\n\t"
 474                 "movel %5,%3@+\n\t"
 475                 "movel %2@+,%5\n\t"
 476                 "addxl %5,%0\n\t"
 477                 "movel %5,%3@+\n\t"
 478                 "movel %2@+,%5\n\t"
 479                 "addxl %5,%0\n\t"
 480                 "movel %5,%3@+\n\t"
 481                 "movel %2@+,%5\n\t"
 482                 "addxl %5,%0\n\t"
 483                 "movel %5,%3@+\n\t"
 484                 "movel %2@+,%5\n\t"
 485                 "addxl %5,%0\n\t"
 486                 "movel %5,%3@+\n\t"
 487                 "movel %2@+,%5\n\t"
 488                 "addxl %5,%0\n\t"
 489                 "movel %5,%3@+\n\t"
 490                 "dbra %1,1b\n\t"
 491                 "clrl %5\n\t"
 492                 "addxl %5,%0\n\t"       /* add X bit */
 493                 "clrw %1\n\t"
 494                 "subql #1,%1\n\t"
 495                 "jcc 1b\n"
 496              "2:\t"
 497                 "movel %4,%1\n\t"       /* restore len from tmp1 */
 498                 "andw #0x1c,%4\n\t"     /* number of rest longs */
 499                 "jeq 4f\n\t"
 500                 "lsrw #2,%4\n\t"
 501                 "subqw #1,%4\n"
 502              "3:\t"
 503                 /* loop for rest longs */
 504                 "movel %2@+,%5\n\t"
 505                 "addxl %5,%0\n\t"
 506                 "movel %5,%3@+\n\t"
 507                 "dbra %4,3b\n\t"
 508                 "clrl %5\n\t"
 509                 "addxl %5,%0\n"         /* add X bit */
 510              "4:\t"
 511                 /* now check for rest bytes that do not fit into longs */
 512                 "andw #3,%1\n\t"
 513                 "jeq 7f\n\t"
 514                 "clrl %5\n\t"           /* clear tmp2 for rest bytes */
 515                 "subqw #2,%1\n\t"
 516                 "jlt 5f\n\t"
 517                 "movew %2@+,%5\n\t"     /* have rest >= 2: get word */
 518                 "movew %5,%3@+\n\t"
 519                 "swap %5\n\t"           /* into bits 16..31 */
 520                 "tstw %1\n\t"           /* another byte? */
 521                 "jeq 6f\n"
 522              "5:\t"
 523                 "moveb %2@,%5\n\t"      /* have odd rest: get byte */
 524                 "moveb %5,%3@+\n\t"
 525                 "lslw #8,%5\n"          /* into bits 8..15; 16..31 untouched */
 526              "6:\t"
 527                 "addl %5,%0\n\t"        /* now add rest long to sum */
 528                 "clrl %5\n\t"
 529                 "addxl %5,%0\n"         /* add X bit */
 530              "7:\t"
 531                 : "=d" (sum), "=d" (len), "=a" (src), "=a" (dst),
 532                   "=&d" (tmp1), "=&d" (tmp2)
 533                 : "0" (sum), "1" (len), "2" (src), "3" (dst)
 534             );
 535     return(sum);
 536 }
 537 EXPORT_SYMBOL(csum_partial_copy_nocheck);
 538 #endif /* CONFIG_COLDFIRE */