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: stable/12/sys/mips/mips/in_cksum.c 325966 2017-11-18 14:26:50Z pfg $");
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  * Checksum routine for Internet Protocol family headers
53  *    (Portable Alpha version).
54  *
55  * This routine is very heavily used in the network
56  * code and should be modified for each CPU to be as fast as possible.
57  */
58 
59 #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
60 #define REDUCE32							  \
61     {									  \
62 	q_util.q = sum;							  \
63 	sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3];	  \
64     }
65 #define REDUCE16							  \
66     {									  \
67 	q_util.q = sum;							  \
68 	l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
69 	sum = l_util.s[0] + l_util.s[1];				  \
70 	ADDCARRY(sum);							  \
71     }
72 
73 static const u_int32_t in_masks[] = {
74 #if _BYTE_ORDER == _LITTLE_ENDIAN
75 	/*0 bytes*/ /*1 byte*/	/*2 bytes*/ /*3 bytes*/
76 	0x00000000, 0x000000FF, 0x0000FFFF, 0x00FFFFFF,	/* offset 0 */
77 	0x00000000, 0x0000FF00, 0x00FFFF00, 0xFFFFFF00,	/* offset 1 */
78 	0x00000000, 0x00FF0000, 0xFFFF0000, 0xFFFF0000,	/* offset 2 */
79 	0x00000000, 0xFF000000, 0xFF000000, 0xFF000000,	/* offset 3 */
80 #else
81 	/*0 bytes*/ /*1 byte*/	/*2 bytes*/ /*3 bytes*/
82 	0x00000000, 0xFF000000, 0xFFFF0000, 0xFFFFFF00,	/* offset 0 */
83 	0x00000000, 0x00FF0000, 0x00FFFF00, 0x00FFFFFF,	/* offset 1 */
84 	0x00000000, 0x0000FF00, 0x0000FFFF, 0x0000FFFF,	/* offset 2 */
85 	0x00000000, 0x000000FF, 0x000000FF, 0x000000FF,	/* offset 3 */
86 #endif
87 };
88 
89 union l_util {
90 	u_int16_t s[2];
91 	u_int32_t l;
92 };
93 union q_util {
94 	u_int16_t s[4];
95 	u_int32_t l[2];
96 	u_int64_t q;
97 };
98 
99 static u_int64_t
in_cksumdata(const void * buf,int len)100 in_cksumdata(const void *buf, int len)
101 {
102 	const u_int32_t *lw = (const u_int32_t *) buf;
103 	u_int64_t sum = 0;
104 	u_int64_t prefilled;
105 	int offset;
106 	union q_util q_util;
107 
108 	if ((3 & (long) lw) == 0 && len == 20) {
109 		sum = (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3] + lw[4];
110 		REDUCE32;
111 		return sum;
112 	}
113 
114 	if ((offset = 3 & (long) lw) != 0) {
115 		const u_int32_t *masks = in_masks + (offset << 2);
116 		lw = (u_int32_t *) (((long) lw) - offset);
117 		sum = *lw++ & masks[len >= 3 ? 3 : len];
118 		len -= 4 - offset;
119 		if (len <= 0) {
120 			REDUCE32;
121 			return sum;
122 		}
123 	}
124 #if 0
125 	/*
126 	 * Force to cache line boundary.
127 	 */
128 	offset = 32 - (0x1f & (long) lw);
129 	if (offset < 32 && len > offset) {
130 		len -= offset;
131 		if (4 & offset) {
132 			sum += (u_int64_t) lw[0];
133 			lw += 1;
134 		}
135 		if (8 & offset) {
136 			sum += (u_int64_t) lw[0] + lw[1];
137 			lw += 2;
138 		}
139 		if (16 & offset) {
140 			sum += (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3];
141 			lw += 4;
142 		}
143 	}
144 #endif
145 	/*
146 	 * access prefilling to start load of next cache line.
147 	 * then add current cache line
148 	 * save result of prefilling for loop iteration.
149 	 */
150 	prefilled = lw[0];
151 	while ((len -= 32) >= 4) {
152 		u_int64_t prefilling = lw[8];
153 		sum += prefilled + lw[1] + lw[2] + lw[3]
154 			+ lw[4] + lw[5] + lw[6] + lw[7];
155 		lw += 8;
156 		prefilled = prefilling;
157 	}
158 	if (len >= 0) {
159 		sum += prefilled + lw[1] + lw[2] + lw[3]
160 			+ lw[4] + lw[5] + lw[6] + lw[7];
161 		lw += 8;
162 	} else {
163 		len += 32;
164 	}
165 	while ((len -= 16) >= 0) {
166 		sum += (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3];
167 		lw += 4;
168 	}
169 	len += 16;
170 	while ((len -= 4) >= 0) {
171 		sum += (u_int64_t) *lw++;
172 	}
173 	len += 4;
174 	if (len > 0)
175 		sum += (u_int64_t) (in_masks[len] & *lw);
176 	REDUCE32;
177 	return sum;
178 }
179 
180 u_short
in_addword(u_short a,u_short b)181 in_addword(u_short a, u_short b)
182 {
183 	u_int64_t sum = a + b;
184 
185 	ADDCARRY(sum);
186 	return (sum);
187 }
188 
189 u_short
in_pseudo(u_int32_t a,u_int32_t b,u_int32_t c)190 in_pseudo(u_int32_t a, u_int32_t b, u_int32_t c)
191 {
192 	u_int64_t sum;
193 	union q_util q_util;
194 	union l_util l_util;
195 
196 	sum = (u_int64_t) a + b + c;
197 	REDUCE16;
198 	return (sum);
199 }
200 
201 u_short
in_cksum_skip(struct mbuf * m,int len,int skip)202 in_cksum_skip(struct mbuf *m, int len, int skip)
203 {
204 	u_int64_t sum = 0;
205 	int mlen = 0;
206 	int clen = 0;
207 	caddr_t addr;
208 	union q_util q_util;
209 	union l_util l_util;
210 
211 	len -= skip;
212 	for (; skip && m; m = m->m_next) {
213 		if (m->m_len > skip) {
214 			mlen = m->m_len - skip;
215 			addr = mtod(m, caddr_t) + skip;
216 			goto skip_start;
217 		} else {
218 			skip -= m->m_len;
219 		}
220 	}
221 
222 	for (; m && len; m = m->m_next) {
223 		if (m->m_len == 0)
224 			continue;
225 		mlen = m->m_len;
226 		addr = mtod(m, caddr_t);
227 skip_start:
228 		if (len < mlen)
229 			mlen = len;
230 
231 		if ((clen ^ (uintptr_t) addr) & 1)
232 			sum += in_cksumdata(addr, mlen) << 8;
233 		else
234 			sum += in_cksumdata(addr, mlen);
235 
236 		clen += mlen;
237 		len -= mlen;
238 	}
239 	REDUCE16;
240 	return (~sum & 0xffff);
241 }
242 
in_cksum_hdr(const struct ip * ip)243 u_int in_cksum_hdr(const struct ip *ip)
244 {
245 	u_int64_t sum = in_cksumdata(ip, sizeof(struct ip));
246 	union q_util q_util;
247 	union l_util l_util;
248 	REDUCE16;
249 	return (~sum & 0xffff);
250 }
251