xref: /freebsd/sys/netinet/in_cksum.c (revision d2033021a73db7b8d910c1ffc52f4d1d0def7162)
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 
38 #include <sys/param.h>
39 #include <sys/mbuf.h>
40 #include <sys/systm.h>
41 #include <netinet/in_systm.h>
42 #include <netinet/in.h>
43 #include <netinet/ip.h>
44 #include <machine/in_cksum.h>
45 
46 /*
47  * These implementations may be overridden on a per-platform basis.  On
48  * platforms with a direct map, the implementation of in_cksum() must handle
49  * unmapped mbufs.
50  */
51 #ifndef HAVE_MD_IN_CKSUM
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 #if _BYTE_ORDER == _LITTLE_ENDIAN
77 	/*0 bytes*/ /*1 byte*/	/*2 bytes*/ /*3 bytes*/
78 	0x00000000, 0x000000FF, 0x0000FFFF, 0x00FFFFFF,	/* offset 0 */
79 	0x00000000, 0x0000FF00, 0x00FFFF00, 0xFFFFFF00,	/* offset 1 */
80 	0x00000000, 0x00FF0000, 0xFFFF0000, 0xFFFF0000,	/* offset 2 */
81 	0x00000000, 0xFF000000, 0xFF000000, 0xFF000000,	/* offset 3 */
82 #else
83 	/*0 bytes*/ /*1 byte*/	/*2 bytes*/ /*3 bytes*/
84 	0x00000000, 0xFF000000, 0xFFFF0000, 0xFFFFFF00,	/* offset 0 */
85 	0x00000000, 0x00FF0000, 0x00FFFF00, 0x00FFFFFF,	/* offset 1 */
86 	0x00000000, 0x0000FF00, 0x0000FFFF, 0x0000FFFF,	/* offset 2 */
87 	0x00000000, 0x000000FF, 0x000000FF, 0x000000FF,	/* offset 3 */
88 #endif
89 };
90 
91 union l_util {
92 	u_int16_t s[2];
93 	u_int32_t l;
94 };
95 union q_util {
96 	u_int16_t s[4];
97 	u_int32_t l[2];
98 	u_int64_t q;
99 };
100 
101 static u_int64_t
102 in_cksumdata(const void *buf, int len)
103 {
104 	const u_int32_t *lw = (const u_int32_t *) buf;
105 	u_int64_t sum = 0;
106 	u_int64_t prefilled;
107 	int offset;
108 	union q_util q_util;
109 
110 	if ((3 & (long) lw) == 0 && len == 20) {
111 		sum = (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3] + lw[4];
112 		REDUCE32;
113 		return sum;
114 	}
115 
116 	if ((offset = 3 & (long) lw) != 0) {
117 		const u_int32_t *masks = in_masks + (offset << 2);
118 		lw = (u_int32_t *) (((long) lw) - offset);
119 		sum = *lw++ & masks[len >= 3 ? 3 : len];
120 		len -= 4 - offset;
121 		if (len <= 0) {
122 			REDUCE32;
123 			return sum;
124 		}
125 	}
126 #if 0
127 	/*
128 	 * Force to cache line boundary.
129 	 */
130 	offset = 32 - (0x1f & (long) lw);
131 	if (offset < 32 && len > offset) {
132 		len -= offset;
133 		if (4 & offset) {
134 			sum += (u_int64_t) lw[0];
135 			lw += 1;
136 		}
137 		if (8 & offset) {
138 			sum += (u_int64_t) lw[0] + lw[1];
139 			lw += 2;
140 		}
141 		if (16 & offset) {
142 			sum += (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3];
143 			lw += 4;
144 		}
145 	}
146 #endif
147 	/*
148 	 * access prefilling to start load of next cache line.
149 	 * then add current cache line
150 	 * save result of prefilling for loop iteration.
151 	 */
152 	prefilled = lw[0];
153 	while ((len -= 32) >= 4) {
154 		u_int64_t prefilling = lw[8];
155 		sum += prefilled + lw[1] + lw[2] + lw[3]
156 			+ lw[4] + lw[5] + lw[6] + lw[7];
157 		lw += 8;
158 		prefilled = prefilling;
159 	}
160 	if (len >= 0) {
161 		sum += prefilled + lw[1] + lw[2] + lw[3]
162 			+ lw[4] + lw[5] + lw[6] + lw[7];
163 		lw += 8;
164 	} else {
165 		len += 32;
166 	}
167 	while ((len -= 16) >= 0) {
168 		sum += (u_int64_t) lw[0] + lw[1] + lw[2] + lw[3];
169 		lw += 4;
170 	}
171 	len += 16;
172 	while ((len -= 4) >= 0) {
173 		sum += (u_int64_t) *lw++;
174 	}
175 	len += 4;
176 	if (len > 0)
177 		sum += (u_int64_t) (in_masks[len] & *lw);
178 	REDUCE32;
179 	return sum;
180 }
181 
182 u_short
183 in_addword(u_short a, u_short b)
184 {
185 	u_int64_t sum = a + b;
186 
187 	ADDCARRY(sum);
188 	return (sum);
189 }
190 
191 u_short
192 in_pseudo(u_int32_t a, u_int32_t b, u_int32_t c)
193 {
194 	u_int64_t sum;
195 	union q_util q_util;
196 	union l_util l_util;
197 
198 	sum = (u_int64_t) a + b + c;
199 	REDUCE16;
200 	return (sum);
201 }
202 
203 struct cksum_skip_partial_args {
204 	uint64_t csum;
205 	int clen;
206 };
207 
208 static int
209 in_cksum_skip_partial(void *arg, void *data, u_int len)
210 {
211 	struct cksum_skip_partial_args *a;
212 
213 	a = arg;
214         if (((uintptr_t)data ^ a->clen) & 1)
215                 a->csum += in_cksumdata(data, len) << 8;
216         else
217                 a->csum += in_cksumdata(data, len);
218 	a->clen += len;
219 	return (0);
220 }
221 
222 u_short
223 in_cksum_skip(struct mbuf *m, int len, int skip)
224 {
225 	struct cksum_skip_partial_args a;
226 	union q_util q_util;
227 	union l_util l_util;
228 	uint64_t sum;
229 
230 	len -= skip;
231 
232 	/*
233 	 * The use of m_apply() allows this routine to operate on unmapped
234 	 * mbufs.
235 	 */
236 	a.csum = 0;
237 	a.clen = 0;
238 	(void)m_apply(m, skip, len, in_cksum_skip_partial, &a);
239 	sum = a.csum;
240 	REDUCE16;
241 	return (~sum & 0xffff);
242 }
243 
244 u_int in_cksum_hdr(const struct ip *ip)
245 {
246 	u_int64_t sum = in_cksumdata(ip, sizeof(struct ip));
247 	union q_util q_util;
248 	union l_util l_util;
249 	REDUCE16;
250 	return (~sum & 0xffff);
251 }
252 
253 #endif /* !HAVE_MD_IN_CKSUM */
254