The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/amd64/amd64/in_cksum.c

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    1 /* $NetBSD: in_cksum.c,v 1.7 1997/09/02 13:18:15 thorpej Exp $ */
    2 
    3 /*-
    4  * SPDX-License-Identifier: BSD-4-Clause
    5  *
    6  * Copyright (c) 1988, 1992, 1993
    7  *      The Regents of the University of California.  All rights reserved.
    8  * Copyright (c) 1996
    9  *      Matt Thomas <matt@3am-software.com>
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 3. All advertising materials mentioning features or use of this software
   20  *    must display the following acknowledgement:
   21  *      This product includes software developed by the University of
   22  *      California, Berkeley and its contributors.
   23  * 4. Neither the name of the University nor the names of its contributors
   24  *    may be used to endorse or promote products derived from this software
   25  *    without specific prior written permission.
   26  *
   27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   37  * SUCH DAMAGE.
   38  *
   39  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
   40  */
   41 
   42 #include <sys/cdefs.h>                  /* RCS ID & Copyright macro defns */
   43 __FBSDID("$FreeBSD: stable/12/sys/amd64/amd64/in_cksum.c 325966 2017-11-18 14:26:50Z pfg $");
   44 
   45 #include <sys/param.h>
   46 #include <sys/mbuf.h>
   47 #include <sys/systm.h>
   48 #include <netinet/in_systm.h>
   49 #include <netinet/in.h>
   50 #include <netinet/ip.h>
   51 #include <machine/in_cksum.h>
   52 
   53 /*
   54  * Checksum routine for Internet Protocol family headers
   55  *    (Portable Alpha version).
   56  *
   57  * This routine is very heavily used in the network
   58  * code and should be modified for each CPU to be as fast as possible.
   59  */
   60 
   61 #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
   62 #define REDUCE32                                                          \
   63     {                                                                     \
   64         q_util.q = sum;                                                   \
   65         sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3];      \
   66     }
   67 #define REDUCE16                                                          \
   68     {                                                                     \
   69         q_util.q = sum;                                                   \
   70         l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
   71         sum = l_util.s[0] + l_util.s[1];                                  \
   72         ADDCARRY(sum);                                                    \
   73     }
   74 
   75 static const u_int32_t in_masks[] = {
   76         /*0 bytes*/ /*1 byte*/  /*2 bytes*/ /*3 bytes*/
   77         0x00000000, 0x000000FF, 0x0000FFFF, 0x00FFFFFF, /* offset 0 */
   78         0x00000000, 0x0000FF00, 0x00FFFF00, 0xFFFFFF00, /* offset 1 */
   79         0x00000000, 0x00FF0000, 0xFFFF0000, 0xFFFF0000, /* offset 2 */
   80         0x00000000, 0xFF000000, 0xFF000000, 0xFF000000, /* offset 3 */
   81 };
   82 
   83 union l_util {
   84         u_int16_t s[2];
   85         u_int32_t l;
   86 };
   87 union q_util {
   88         u_int16_t s[4];
   89         u_int32_t l[2];
   90         u_int64_t q;
   91 };
   92 
   93 static u_int64_t
   94 in_cksumdata(const void *buf, int len)
   95 {
   96         const u_int32_t *lw = (const u_int32_t *) buf;
   97         u_int64_t sum = 0;
   98         u_int64_t prefilled;
   99         int offset;
  100         union q_util q_util;
  101 
  102         if ((3 & (long) lw) == 0 && len == 20) {
  103              sum = (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3] + lw[4];
  104              REDUCE32;
  105              return sum;
  106         }
  107 
  108         if ((offset = 3 & (long) lw) != 0) {
  109                 const u_int32_t *masks = in_masks + (offset << 2);
  110                 lw = (u_int32_t *) (((long) lw) - offset);
  111                 sum = *lw++ & masks[len >= 3 ? 3 : len];
  112                 len -= 4 - offset;
  113                 if (len <= 0) {
  114                         REDUCE32;
  115                         return sum;
  116                 }
  117         }
  118 #if 0
  119         /*
  120          * Force to cache line boundary.
  121          */
  122         offset = 32 - (0x1f & (long) lw);
  123         if (offset < 32 && len > offset) {
  124                 len -= offset;
  125                 if (4 & offset) {
  126                         sum += (u_int64_t) lw[0];
  127                         lw += 1;
  128                 }
  129                 if (8 & offset) {
  130                         sum += (u_int64_t) lw[0] + lw[1];
  131                         lw += 2;
  132                 }
  133                 if (16 & offset) {
  134                         sum += (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3];
  135                         lw += 4;
  136                 }
  137         }
  138 #endif
  139         /*
  140          * access prefilling to start load of next cache line.
  141          * then add current cache line
  142          * save result of prefilling for loop iteration.
  143          */
  144         prefilled = lw[0];
  145         while ((len -= 32) >= 4) {
  146                 u_int64_t prefilling = lw[8];
  147                 sum += prefilled + lw[1] + lw[2] + lw[3]
  148                         + lw[4] + lw[5] + lw[6] + lw[7];
  149                 lw += 8;
  150                 prefilled = prefilling;
  151         }
  152         if (len >= 0) {
  153                 sum += prefilled + lw[1] + lw[2] + lw[3]
  154                         + lw[4] + lw[5] + lw[6] + lw[7];
  155                 lw += 8;
  156         } else {
  157                 len += 32;
  158         }
  159         while ((len -= 16) >= 0) {
  160                 sum += (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3];
  161                 lw += 4;
  162         }
  163         len += 16;
  164         while ((len -= 4) >= 0) {
  165                 sum += (u_int64_t) *lw++;
  166         }
  167         len += 4;
  168         if (len > 0)
  169                 sum += (u_int64_t) (in_masks[len] & *lw);
  170         REDUCE32;
  171         return sum;
  172 }
  173 
  174 u_short
  175 in_addword(u_short a, u_short b)
  176 {
  177         u_int64_t sum = a + b;
  178 
  179         ADDCARRY(sum);
  180         return (sum);
  181 }
  182 
  183 u_short
  184 in_pseudo(u_int32_t a, u_int32_t b, u_int32_t c)
  185 {
  186         u_int64_t sum;
  187         union q_util q_util;
  188         union l_util l_util;
  189                     
  190         sum = (u_int64_t) a + b + c;
  191         REDUCE16;
  192         return (sum);
  193 }
  194 
  195 u_short
  196 in_cksum_skip(struct mbuf *m, int len, int skip)
  197 {
  198         u_int64_t sum = 0;
  199         int mlen = 0;
  200         int clen = 0;
  201         caddr_t addr;
  202         union q_util q_util;
  203         union l_util l_util;
  204 
  205         len -= skip;
  206         for (; skip && m; m = m->m_next) {
  207                 if (m->m_len > skip) {
  208                         mlen = m->m_len - skip;
  209                         addr = mtod(m, caddr_t) + skip;
  210                         goto skip_start;
  211                 } else {
  212                         skip -= m->m_len;
  213                 }
  214         }
  215 
  216         for (; m && len; m = m->m_next) {
  217                 if (m->m_len == 0)
  218                         continue;
  219                 mlen = m->m_len;
  220                 addr = mtod(m, caddr_t);
  221 skip_start:
  222                 if (len < mlen)
  223                         mlen = len;
  224                 if ((clen ^ (long) addr) & 1)
  225                     sum += in_cksumdata(addr, mlen) << 8;
  226                 else
  227                     sum += in_cksumdata(addr, mlen);
  228 
  229                 clen += mlen;
  230                 len -= mlen;
  231         }
  232         REDUCE16;
  233         return (~sum & 0xffff);
  234 }
  235 
  236 u_int in_cksum_hdr(const struct ip *ip)
  237 {
  238     u_int64_t sum = in_cksumdata(ip, sizeof(struct ip));
  239     union q_util q_util;
  240     union l_util l_util;
  241     REDUCE16;
  242     return (~sum & 0xffff);
  243 }

Cache object: 89a46e9d4eb56c19300609c6ca41dbf5


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