in_cksum.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-4-Clause
    3  *
    4  * Copyright (c) 1988, 1992, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  * Copyright (c) 1996
    7  *      Matt Thomas <matt@3am-software.com>
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 3. All advertising materials mentioning features or use of this software
   18  *    must display the following acknowledgement:
   19  *      This product includes software developed by the University of
   20  *      California, Berkeley and its contributors.
   21  * 4. Neither the name of the University nor the names of its contributors
   22  *    may be used to endorse or promote products derived from this software
   23  *    without specific prior written permission.
   24  *
   25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   35  * SUCH DAMAGE.
   36  *
   37  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
   38  */
   39 
   40 #include <sys/cdefs.h>
   41 __FBSDID("$FreeBSD$");
   42 
   43 #include <sys/param.h>
   44 #include <sys/mbuf.h>
   45 #include <sys/systm.h>
   46 #include <netinet/in_systm.h>
   47 #include <netinet/in.h>
   48 #include <netinet/ip.h>
   49 #include <machine/in_cksum.h>
   50 
   51 /*
   52  * These implementations may be overridden on a per-platform basis.  On
   53  * platforms with a direct map, the implementation of in_cksum() must handle
   54  * unmapped mbufs.
   55  */
   56 #ifndef HAVE_MD_IN_CKSUM
   57 
   58 /*
   59  * Checksum routine for Internet Protocol family headers
   60  *    (Portable Alpha version).
   61  *
   62  * This routine is very heavily used in the network
   63  * code and should be modified for each CPU to be as fast as possible.
   64  */
   65 
   66 #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
   67 #define REDUCE32                                                          \
   68     {                                                                     \
   69         q_util.q = sum;                                                   \
   70         sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3];      \
   71     }
   72 #define REDUCE16                                                          \
   73     {                                                                     \
   74         q_util.q = sum;                                                   \
   75         l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
   76         sum = l_util.s[0] + l_util.s[1];                                  \
   77         ADDCARRY(sum);                                                    \
   78     }
   79 
   80 static const u_int32_t in_masks[] = {
   81 #if _BYTE_ORDER == _LITTLE_ENDIAN
   82         /*0 bytes*/ /*1 byte*/  /*2 bytes*/ /*3 bytes*/
   83         0x00000000, 0x000000FF, 0x0000FFFF, 0x00FFFFFF, /* offset 0 */
   84         0x00000000, 0x0000FF00, 0x00FFFF00, 0xFFFFFF00, /* offset 1 */
   85         0x00000000, 0x00FF0000, 0xFFFF0000, 0xFFFF0000, /* offset 2 */
   86         0x00000000, 0xFF000000, 0xFF000000, 0xFF000000, /* offset 3 */
   87 #else
   88         /*0 bytes*/ /*1 byte*/  /*2 bytes*/ /*3 bytes*/
   89         0x00000000, 0xFF000000, 0xFFFF0000, 0xFFFFFF00, /* offset 0 */
   90         0x00000000, 0x00FF0000, 0x00FFFF00, 0x00FFFFFF, /* offset 1 */
   91         0x00000000, 0x0000FF00, 0x0000FFFF, 0x0000FFFF, /* offset 2 */
   92         0x00000000, 0x000000FF, 0x000000FF, 0x000000FF, /* offset 3 */
   93 #endif
   94 };
   95 
   96 union l_util {
   97         u_int16_t s[2];
   98         u_int32_t l;
   99 };
  100 union q_util {
  101         u_int16_t s[4];
  102         u_int32_t l[2];
  103         u_int64_t q;
  104 };
  105 
  106 static u_int64_t
  107 in_cksumdata(const void *buf, int len)
  108 {
  109         const u_int32_t *lw = (const u_int32_t *) buf;
  110         u_int64_t sum = 0;
  111         u_int64_t prefilled;
  112         int offset;
  113         union q_util q_util;
  114 
  115         if ((3 & (long) lw) == 0 && len == 20) {
  116                 sum = (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3] + lw[4];
  117                 REDUCE32;
  118                 return sum;
  119         }
  120 
  121         if ((offset = 3 & (long) lw) != 0) {
  122                 const u_int32_t *masks = in_masks + (offset << 2);
  123                 lw = (u_int32_t *) (((long) lw) - offset);
  124                 sum = *lw++ & masks[len >= 3 ? 3 : len];
  125                 len -= 4 - offset;
  126                 if (len <= 0) {
  127                         REDUCE32;
  128                         return sum;
  129                 }
  130         }
  131 #if 0
  132         /*
  133          * Force to cache line boundary.
  134          */
  135         offset = 32 - (0x1f & (long) lw);
  136         if (offset < 32 && len > offset) {
  137                 len -= offset;
  138                 if (4 & offset) {
  139                         sum += (u_int64_t) lw[0];
  140                         lw += 1;
  141                 }
  142                 if (8 & offset) {
  143                         sum += (u_int64_t) lw[0] + lw[1];
  144                         lw += 2;
  145                 }
  146                 if (16 & offset) {
  147                         sum += (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3];
  148                         lw += 4;
  149                 }
  150         }
  151 #endif
  152         /*
  153          * access prefilling to start load of next cache line.
  154          * then add current cache line
  155          * save result of prefilling for loop iteration.
  156          */
  157         prefilled = lw[0];
  158         while ((len -= 32) >= 4) {
  159                 u_int64_t prefilling = lw[8];
  160                 sum += prefilled + lw[1] + lw[2] + lw[3]
  161                         + lw[4] + lw[5] + lw[6] + lw[7];
  162                 lw += 8;
  163                 prefilled = prefilling;
  164         }
  165         if (len >= 0) {
  166                 sum += prefilled + lw[1] + lw[2] + lw[3]
  167                         + lw[4] + lw[5] + lw[6] + lw[7];
  168                 lw += 8;
  169         } else {
  170                 len += 32;
  171         }
  172         while ((len -= 16) >= 0) {
  173                 sum += (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3];
  174                 lw += 4;
  175         }
  176         len += 16;
  177         while ((len -= 4) >= 0) {
  178                 sum += (u_int64_t) *lw++;
  179         }
  180         len += 4;
  181         if (len > 0)
  182                 sum += (u_int64_t) (in_masks[len] & *lw);
  183         REDUCE32;
  184         return sum;
  185 }
  186 
  187 u_short
  188 in_addword(u_short a, u_short b)
  189 {
  190         u_int64_t sum = a + b;
  191 
  192         ADDCARRY(sum);
  193         return (sum);
  194 }
  195 
  196 u_short
  197 in_pseudo(u_int32_t a, u_int32_t b, u_int32_t c)
  198 {
  199         u_int64_t sum;
  200         union q_util q_util;
  201         union l_util l_util;
  202 
  203         sum = (u_int64_t) a + b + c;
  204         REDUCE16;
  205         return (sum);
  206 }
  207 
  208 struct cksum_skip_partial_args {
  209         uint64_t csum;
  210         int clen;
  211 };
  212 
  213 static int
  214 in_cksum_skip_partial(void *arg, void *data, u_int len)
  215 {
  216         struct cksum_skip_partial_args *a;
  217 
  218         a = arg;
  219         if (((uintptr_t)data ^ a->clen) & 1)
  220                 a->csum += in_cksumdata(data, len) << 8;
  221         else
  222                 a->csum += in_cksumdata(data, len);
  223         a->clen += len;
  224         return (0);
  225 }
  226 
  227 u_short
  228 in_cksum_skip(struct mbuf *m, int len, int skip)
  229 {
  230         struct cksum_skip_partial_args a;
  231         union q_util q_util;
  232         union l_util l_util;
  233         uint64_t sum;
  234 
  235         len -= skip;
  236 
  237         /*
  238          * The use of m_apply() allows this routine to operate on unmapped
  239          * mbufs.
  240          */
  241         a.csum = 0;
  242         a.clen = 0;
  243         (void)m_apply(m, skip, len, in_cksum_skip_partial, &a);
  244         sum = a.csum;
  245         REDUCE16;
  246         return (~sum & 0xffff);
  247 }
  248 
  249 u_int in_cksum_hdr(const struct ip *ip)
  250 {
  251         u_int64_t sum = in_cksumdata(ip, sizeof(struct ip));
  252         union q_util q_util;
  253         union l_util l_util;
  254         REDUCE16;
  255         return (~sum & 0xffff);
  256 }
  257 
  258 #endif /* !HAVE_MD_IN_CKSUM */

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FreeBSD/Linux Kernel Cross Reference sys/netinet/in_cksum.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet/in_cksum.c