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1da177e4 LT |
1 | /* |
2 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
3 | * operating system. INET is implemented using the BSD Socket | |
4 | * interface as the means of communication with the user level. | |
5 | * | |
6 | * MIPS specific IP/TCP/UDP checksumming routines | |
7 | * | |
8 | * Authors: Ralf Baechle, <ralf@waldorf-gmbh.de> | |
9 | * Lots of code moved from tcp.c and ip.c; see those files | |
10 | * for more names. | |
11 | * | |
12 | * This program is free software; you can redistribute it and/or | |
13 | * modify it under the terms of the GNU General Public License | |
14 | * as published by the Free Software Foundation; either version | |
15 | * 2 of the License, or (at your option) any later version. | |
1da177e4 LT |
16 | */ |
17 | #include <linux/module.h> | |
18 | #include <linux/types.h> | |
19 | ||
20 | #include <net/checksum.h> | |
21 | #include <asm/byteorder.h> | |
22 | #include <asm/string.h> | |
23 | #include <asm/uaccess.h> | |
24 | ||
25 | #define addc(_t,_r) \ | |
26 | __asm__ __volatile__ ( \ | |
27 | " add %0, %1, %0\n" \ | |
28 | " addc %0, %%r0, %0\n" \ | |
29 | : "=r"(_t) \ | |
30 | : "r"(_r), "0"(_t)); | |
31 | ||
32 | static inline unsigned short from32to16(unsigned int x) | |
33 | { | |
34 | /* 32 bits --> 16 bits + carry */ | |
35 | x = (x & 0xffff) + (x >> 16); | |
36 | /* 16 bits + carry --> 16 bits including carry */ | |
37 | x = (x & 0xffff) + (x >> 16); | |
38 | return (unsigned short)x; | |
39 | } | |
40 | ||
41 | static inline unsigned int do_csum(const unsigned char * buff, int len) | |
42 | { | |
43 | int odd, count; | |
44 | unsigned int result = 0; | |
45 | ||
46 | if (len <= 0) | |
47 | goto out; | |
48 | odd = 1 & (unsigned long) buff; | |
49 | if (odd) { | |
50 | result = be16_to_cpu(*buff); | |
51 | len--; | |
52 | buff++; | |
53 | } | |
54 | count = len >> 1; /* nr of 16-bit words.. */ | |
55 | if (count) { | |
56 | if (2 & (unsigned long) buff) { | |
57 | result += *(unsigned short *) buff; | |
58 | count--; | |
59 | len -= 2; | |
60 | buff += 2; | |
61 | } | |
62 | count >>= 1; /* nr of 32-bit words.. */ | |
63 | if (count) { | |
64 | while (count >= 4) { | |
65 | unsigned int r1, r2, r3, r4; | |
66 | r1 = *(unsigned int *)(buff + 0); | |
67 | r2 = *(unsigned int *)(buff + 4); | |
68 | r3 = *(unsigned int *)(buff + 8); | |
69 | r4 = *(unsigned int *)(buff + 12); | |
70 | addc(result, r1); | |
71 | addc(result, r2); | |
72 | addc(result, r3); | |
73 | addc(result, r4); | |
74 | count -= 4; | |
75 | buff += 16; | |
76 | } | |
77 | while (count) { | |
78 | unsigned int w = *(unsigned int *) buff; | |
79 | count--; | |
80 | buff += 4; | |
81 | addc(result, w); | |
82 | } | |
83 | result = (result & 0xffff) + (result >> 16); | |
84 | } | |
85 | if (len & 2) { | |
86 | result += *(unsigned short *) buff; | |
87 | buff += 2; | |
88 | } | |
89 | } | |
90 | if (len & 1) | |
91 | result += le16_to_cpu(*buff); | |
92 | result = from32to16(result); | |
93 | if (odd) | |
94 | result = swab16(result); | |
95 | out: | |
96 | return result; | |
97 | } | |
98 | ||
99 | /* | |
100 | * computes a partial checksum, e.g. for TCP/UDP fragments | |
101 | */ | |
7814e4b6 AV |
102 | /* |
103 | * why bother folding? | |
104 | */ | |
105 | __wsum csum_partial(const void *buff, int len, __wsum sum) | |
1da177e4 LT |
106 | { |
107 | unsigned int result = do_csum(buff, len); | |
108 | addc(result, sum); | |
7814e4b6 | 109 | return (__force __wsum)from32to16(result); |
1da177e4 LT |
110 | } |
111 | ||
112 | EXPORT_SYMBOL(csum_partial); | |
113 | ||
114 | /* | |
115 | * copy while checksumming, otherwise like csum_partial | |
116 | */ | |
7814e4b6 AV |
117 | __wsum csum_partial_copy_nocheck(const void *src, void *dst, |
118 | int len, __wsum sum) | |
1da177e4 LT |
119 | { |
120 | /* | |
121 | * It's 2:30 am and I don't feel like doing it real ... | |
122 | * This is lots slower than the real thing (tm) | |
123 | */ | |
124 | sum = csum_partial(src, len, sum); | |
125 | memcpy(dst, src, len); | |
126 | ||
127 | return sum; | |
128 | } | |
129 | EXPORT_SYMBOL(csum_partial_copy_nocheck); | |
130 | ||
131 | /* | |
132 | * Copy from userspace and compute checksum. If we catch an exception | |
133 | * then zero the rest of the buffer. | |
134 | */ | |
7814e4b6 AV |
135 | __wsum csum_partial_copy_from_user(const void __user *src, |
136 | void *dst, int len, | |
137 | __wsum sum, int *err_ptr) | |
1da177e4 LT |
138 | { |
139 | int missing; | |
140 | ||
141 | missing = copy_from_user(dst, src, len); | |
142 | if (missing) { | |
143 | memset(dst + len - missing, 0, missing); | |
144 | *err_ptr = -EFAULT; | |
145 | } | |
146 | ||
147 | return csum_partial(dst, len, sum); | |
148 | } | |
149 | EXPORT_SYMBOL(csum_partial_copy_from_user); |