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
in_cksumdata(const void * buf,int len)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
in_addword(u_short a,u_short b)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
in_pseudo(u_int32_t a,u_int32_t b,u_int32_t c)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
in_cksum_skip(struct mbuf * m,int len,int skip)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 
in_cksum_hdr(const struct ip * ip)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 }
244