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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * Network Checksum & Copy routine | |
4 | * | |
5 | * Copyright (C) 1999, 2003-2004 Hewlett-Packard Co | |
6 | * Stephane Eranian <eranian@hpl.hp.com> | |
7 | * | |
8 | * Most of the code has been imported from Linux/Alpha | |
9 | */ | |
10 | ||
11 | #include <linux/module.h> | |
12 | #include <linux/types.h> | |
13 | #include <linux/string.h> | |
14 | ||
7c0f6ba6 | 15 | #include <linux/uaccess.h> |
1da177e4 LT |
16 | |
17 | /* | |
18 | * XXX Fixme: those 2 inlines are meant for debugging and will go away | |
19 | */ | |
20 | static inline unsigned | |
21 | short from64to16(unsigned long x) | |
22 | { | |
23 | /* add up 32-bit words for 33 bits */ | |
24 | x = (x & 0xffffffff) + (x >> 32); | |
25 | /* add up 16-bit and 17-bit words for 17+c bits */ | |
26 | x = (x & 0xffff) + (x >> 16); | |
27 | /* add up 16-bit and 2-bit for 16+c bit */ | |
28 | x = (x & 0xffff) + (x >> 16); | |
29 | /* add up carry.. */ | |
30 | x = (x & 0xffff) + (x >> 16); | |
31 | return x; | |
32 | } | |
33 | ||
34 | static inline | |
35 | unsigned long do_csum_c(const unsigned char * buff, int len, unsigned int psum) | |
36 | { | |
37 | int odd, count; | |
38 | unsigned long result = (unsigned long)psum; | |
39 | ||
40 | if (len <= 0) | |
41 | goto out; | |
42 | odd = 1 & (unsigned long) buff; | |
43 | if (odd) { | |
44 | result = *buff << 8; | |
45 | len--; | |
46 | buff++; | |
47 | } | |
48 | count = len >> 1; /* nr of 16-bit words.. */ | |
49 | if (count) { | |
50 | if (2 & (unsigned long) buff) { | |
51 | result += *(unsigned short *) buff; | |
52 | count--; | |
53 | len -= 2; | |
54 | buff += 2; | |
55 | } | |
56 | count >>= 1; /* nr of 32-bit words.. */ | |
57 | if (count) { | |
58 | if (4 & (unsigned long) buff) { | |
59 | result += *(unsigned int *) buff; | |
60 | count--; | |
61 | len -= 4; | |
62 | buff += 4; | |
63 | } | |
64 | count >>= 1; /* nr of 64-bit words.. */ | |
65 | if (count) { | |
66 | unsigned long carry = 0; | |
67 | do { | |
68 | unsigned long w = *(unsigned long *) buff; | |
69 | count--; | |
70 | buff += 8; | |
71 | result += carry; | |
72 | result += w; | |
73 | carry = (w > result); | |
74 | } while (count); | |
75 | result += carry; | |
76 | result = (result & 0xffffffff) + (result >> 32); | |
77 | } | |
78 | if (len & 4) { | |
79 | result += *(unsigned int *) buff; | |
80 | buff += 4; | |
81 | } | |
82 | } | |
83 | if (len & 2) { | |
84 | result += *(unsigned short *) buff; | |
85 | buff += 2; | |
86 | } | |
87 | } | |
88 | if (len & 1) | |
89 | result += *buff; | |
90 | ||
91 | result = from64to16(result); | |
92 | ||
93 | if (odd) | |
94 | result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); | |
95 | ||
96 | out: | |
97 | return result; | |
98 | } | |
99 | ||
100 | /* | |
101 | * XXX Fixme | |
102 | * | |
103 | * This is very ugly but temporary. THIS NEEDS SERIOUS ENHANCEMENTS. | |
104 | * But it's very tricky to get right even in C. | |
105 | */ | |
106 | extern unsigned long do_csum(const unsigned char *, long); | |
107 | ||
32252996 AV |
108 | __wsum |
109 | csum_partial_copy_from_user(const void __user *src, void *dst, | |
110 | int len, __wsum psum, int *errp) | |
1da177e4 LT |
111 | { |
112 | unsigned long result; | |
113 | ||
114 | /* XXX Fixme | |
115 | * for now we separate the copy from checksum for obvious | |
116 | * alignment difficulties. Look at the Alpha code and you'll be | |
117 | * scared. | |
118 | */ | |
119 | ||
120 | if (__copy_from_user(dst, src, len) != 0 && errp) | |
121 | *errp = -EFAULT; | |
122 | ||
123 | result = do_csum(dst, len); | |
124 | ||
125 | /* add in old sum, and carry.. */ | |
32252996 | 126 | result += (__force u32)psum; |
1da177e4 LT |
127 | /* 32+c bits -> 32 bits */ |
128 | result = (result & 0xffffffff) + (result >> 32); | |
32252996 | 129 | return (__force __wsum)result; |
1da177e4 LT |
130 | } |
131 | ||
b1bdb691 DH |
132 | EXPORT_SYMBOL(csum_partial_copy_from_user); |
133 | ||
32252996 AV |
134 | __wsum |
135 | csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum) | |
1da177e4 | 136 | { |
32252996 AV |
137 | return csum_partial_copy_from_user((__force const void __user *)src, |
138 | dst, len, sum, NULL); | |
1da177e4 LT |
139 | } |
140 | ||
141 | EXPORT_SYMBOL(csum_partial_copy_nocheck); |