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