blob: 118daf5a0632cc505f2f88574ab645c4b79e14a5 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 */
19static inline unsigned
20short 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
33static inline
34unsigned 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
95out:
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 */
105extern unsigned long do_csum(const unsigned char *, long);
106
Al Viro32252992006-11-14 21:16:30 -0800107__wsum
108csum_partial_copy_from_user(const void __user *src, void *dst,
109 int len, __wsum psum, int *errp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110{
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.. */
Al Viro32252992006-11-14 21:16:30 -0800125 result += (__force u32)psum;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 /* 32+c bits -> 32 bits */
127 result = (result & 0xffffffff) + (result >> 32);
Al Viro32252992006-11-14 21:16:30 -0800128 return (__force __wsum)result;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129}
130
David Howellsb1bdb692007-04-27 15:28:45 -0700131EXPORT_SYMBOL(csum_partial_copy_from_user);
132
Al Viro32252992006-11-14 21:16:30 -0800133__wsum
134csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135{
Al Viro32252992006-11-14 21:16:30 -0800136 return csum_partial_copy_from_user((__force const void __user *)src,
137 dst, len, sum, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138}
139
140EXPORT_SYMBOL(csum_partial_copy_nocheck);