Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * Network Checksum & Copy routine | |
3 | * | |
4 | * Copyright (C) 1999, 2003-2004 Hewlett-Packard Co | |
5 | * Stephane Eranian <eranian@hpl.hp.com> | |
6 | * | |
7 | * Most of the code has been imported from Linux/Alpha | |
8 | */ | |
9 | ||
10 | #include <linux/module.h> | |
11 | #include <linux/types.h> | |
12 | #include <linux/string.h> | |
13 | ||
14 | #include <asm/uaccess.h> | |
15 | ||
16 | /* | |
17 | * XXX Fixme: those 2 inlines are meant for debugging and will go away | |
18 | */ | |
19 | static inline unsigned | |
20 | short from64to16(unsigned long x) | |
21 | { | |
22 | /* add up 32-bit words for 33 bits */ | |
23 | x = (x & 0xffffffff) + (x >> 32); | |
24 | /* add up 16-bit and 17-bit words for 17+c bits */ | |
25 | x = (x & 0xffff) + (x >> 16); | |
26 | /* add up 16-bit and 2-bit for 16+c bit */ | |
27 | x = (x & 0xffff) + (x >> 16); | |
28 | /* add up carry.. */ | |
29 | x = (x & 0xffff) + (x >> 16); | |
30 | return x; | |
31 | } | |
32 | ||
33 | static inline | |
34 | unsigned long do_csum_c(const unsigned char * buff, int len, unsigned int psum) | |
35 | { | |
36 | int odd, count; | |
37 | unsigned long result = (unsigned long)psum; | |
38 | ||
39 | if (len <= 0) | |
40 | goto out; | |
41 | odd = 1 & (unsigned long) buff; | |
42 | if (odd) { | |
43 | result = *buff << 8; | |
44 | len--; | |
45 | buff++; | |
46 | } | |
47 | count = len >> 1; /* nr of 16-bit words.. */ | |
48 | if (count) { | |
49 | if (2 & (unsigned long) buff) { | |
50 | result += *(unsigned short *) buff; | |
51 | count--; | |
52 | len -= 2; | |
53 | buff += 2; | |
54 | } | |
55 | count >>= 1; /* nr of 32-bit words.. */ | |
56 | if (count) { | |
57 | if (4 & (unsigned long) buff) { | |
58 | result += *(unsigned int *) buff; | |
59 | count--; | |
60 | len -= 4; | |
61 | buff += 4; | |
62 | } | |
63 | count >>= 1; /* nr of 64-bit words.. */ | |
64 | if (count) { | |
65 | unsigned long carry = 0; | |
66 | do { | |
67 | unsigned long w = *(unsigned long *) buff; | |
68 | count--; | |
69 | buff += 8; | |
70 | result += carry; | |
71 | result += w; | |
72 | carry = (w > result); | |
73 | } while (count); | |
74 | result += carry; | |
75 | result = (result & 0xffffffff) + (result >> 32); | |
76 | } | |
77 | if (len & 4) { | |
78 | result += *(unsigned int *) buff; | |
79 | buff += 4; | |
80 | } | |
81 | } | |
82 | if (len & 2) { | |
83 | result += *(unsigned short *) buff; | |
84 | buff += 2; | |
85 | } | |
86 | } | |
87 | if (len & 1) | |
88 | result += *buff; | |
89 | ||
90 | result = from64to16(result); | |
91 | ||
92 | if (odd) | |
93 | result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); | |
94 | ||
95 | out: | |
96 | return result; | |
97 | } | |
98 | ||
99 | /* | |
100 | * XXX Fixme | |
101 | * | |
102 | * This is very ugly but temporary. THIS NEEDS SERIOUS ENHANCEMENTS. | |
103 | * But it's very tricky to get right even in C. | |
104 | */ | |
105 | extern unsigned long do_csum(const unsigned char *, long); | |
106 | ||
107 | static unsigned int | |
108 | do_csum_partial_copy_from_user (const unsigned char __user *src, unsigned char *dst, | |
109 | int len, unsigned int psum, int *errp) | |
110 | { | |
111 | unsigned long result; | |
112 | ||
113 | /* XXX Fixme | |
114 | * for now we separate the copy from checksum for obvious | |
115 | * alignment difficulties. Look at the Alpha code and you'll be | |
116 | * scared. | |
117 | */ | |
118 | ||
119 | if (__copy_from_user(dst, src, len) != 0 && errp) | |
120 | *errp = -EFAULT; | |
121 | ||
122 | result = do_csum(dst, len); | |
123 | ||
124 | /* add in old sum, and carry.. */ | |
125 | result += psum; | |
126 | /* 32+c bits -> 32 bits */ | |
127 | result = (result & 0xffffffff) + (result >> 32); | |
128 | return result; | |
129 | } | |
130 | ||
131 | unsigned int | |
132 | csum_partial_copy_from_user (const unsigned char __user *src, unsigned char *dst, | |
133 | int len, unsigned int sum, int *errp) | |
134 | { | |
135 | if (!access_ok(VERIFY_READ, src, len)) { | |
136 | *errp = -EFAULT; | |
137 | memset(dst, 0, len); | |
138 | return sum; | |
139 | } | |
140 | ||
141 | return do_csum_partial_copy_from_user(src, dst, len, sum, errp); | |
142 | } | |
143 | ||
144 | unsigned int | |
145 | csum_partial_copy_nocheck(const unsigned char __user *src, unsigned char *dst, | |
146 | int len, unsigned int sum) | |
147 | { | |
148 | return do_csum_partial_copy_from_user(src, dst, len, sum, NULL); | |
149 | } | |
150 | ||
151 | EXPORT_SYMBOL(csum_partial_copy_nocheck); |