mirror of
https://github.com/torvalds/linux.git
synced 2024-11-15 08:31:55 +00:00
7814e4b6d6
* sanitized prototypes, annotated * kill shift-by-16 in checksum calculation Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
152 lines
3.6 KiB
C
152 lines
3.6 KiB
C
/*
|
|
* INET An implementation of the TCP/IP protocol suite for the LINUX
|
|
* operating system. INET is implemented using the BSD Socket
|
|
* interface as the means of communication with the user level.
|
|
*
|
|
* MIPS specific IP/TCP/UDP checksumming routines
|
|
*
|
|
* Authors: Ralf Baechle, <ralf@waldorf-gmbh.de>
|
|
* Lots of code moved from tcp.c and ip.c; see those files
|
|
* for more names.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the License, or (at your option) any later version.
|
|
*
|
|
* $Id: checksum.c,v 1.3 1997/12/01 17:57:34 ralf Exp $
|
|
*/
|
|
#include <linux/module.h>
|
|
#include <linux/types.h>
|
|
|
|
#include <net/checksum.h>
|
|
#include <asm/byteorder.h>
|
|
#include <asm/string.h>
|
|
#include <asm/uaccess.h>
|
|
|
|
#define addc(_t,_r) \
|
|
__asm__ __volatile__ ( \
|
|
" add %0, %1, %0\n" \
|
|
" addc %0, %%r0, %0\n" \
|
|
: "=r"(_t) \
|
|
: "r"(_r), "0"(_t));
|
|
|
|
static inline unsigned short from32to16(unsigned int x)
|
|
{
|
|
/* 32 bits --> 16 bits + carry */
|
|
x = (x & 0xffff) + (x >> 16);
|
|
/* 16 bits + carry --> 16 bits including carry */
|
|
x = (x & 0xffff) + (x >> 16);
|
|
return (unsigned short)x;
|
|
}
|
|
|
|
static inline unsigned int do_csum(const unsigned char * buff, int len)
|
|
{
|
|
int odd, count;
|
|
unsigned int result = 0;
|
|
|
|
if (len <= 0)
|
|
goto out;
|
|
odd = 1 & (unsigned long) buff;
|
|
if (odd) {
|
|
result = be16_to_cpu(*buff);
|
|
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) {
|
|
while (count >= 4) {
|
|
unsigned int r1, r2, r3, r4;
|
|
r1 = *(unsigned int *)(buff + 0);
|
|
r2 = *(unsigned int *)(buff + 4);
|
|
r3 = *(unsigned int *)(buff + 8);
|
|
r4 = *(unsigned int *)(buff + 12);
|
|
addc(result, r1);
|
|
addc(result, r2);
|
|
addc(result, r3);
|
|
addc(result, r4);
|
|
count -= 4;
|
|
buff += 16;
|
|
}
|
|
while (count) {
|
|
unsigned int w = *(unsigned int *) buff;
|
|
count--;
|
|
buff += 4;
|
|
addc(result, w);
|
|
}
|
|
result = (result & 0xffff) + (result >> 16);
|
|
}
|
|
if (len & 2) {
|
|
result += *(unsigned short *) buff;
|
|
buff += 2;
|
|
}
|
|
}
|
|
if (len & 1)
|
|
result += le16_to_cpu(*buff);
|
|
result = from32to16(result);
|
|
if (odd)
|
|
result = swab16(result);
|
|
out:
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* computes a partial checksum, e.g. for TCP/UDP fragments
|
|
*/
|
|
/*
|
|
* why bother folding?
|
|
*/
|
|
__wsum csum_partial(const void *buff, int len, __wsum sum)
|
|
{
|
|
unsigned int result = do_csum(buff, len);
|
|
addc(result, sum);
|
|
return (__force __wsum)from32to16(result);
|
|
}
|
|
|
|
EXPORT_SYMBOL(csum_partial);
|
|
|
|
/*
|
|
* copy while checksumming, otherwise like csum_partial
|
|
*/
|
|
__wsum csum_partial_copy_nocheck(const void *src, void *dst,
|
|
int len, __wsum sum)
|
|
{
|
|
/*
|
|
* It's 2:30 am and I don't feel like doing it real ...
|
|
* This is lots slower than the real thing (tm)
|
|
*/
|
|
sum = csum_partial(src, len, sum);
|
|
memcpy(dst, src, len);
|
|
|
|
return sum;
|
|
}
|
|
EXPORT_SYMBOL(csum_partial_copy_nocheck);
|
|
|
|
/*
|
|
* Copy from userspace and compute checksum. If we catch an exception
|
|
* then zero the rest of the buffer.
|
|
*/
|
|
__wsum csum_partial_copy_from_user(const void __user *src,
|
|
void *dst, int len,
|
|
__wsum sum, int *err_ptr)
|
|
{
|
|
int missing;
|
|
|
|
missing = copy_from_user(dst, src, len);
|
|
if (missing) {
|
|
memset(dst + len - missing, 0, missing);
|
|
*err_ptr = -EFAULT;
|
|
}
|
|
|
|
return csum_partial(dst, len, sum);
|
|
}
|
|
EXPORT_SYMBOL(csum_partial_copy_from_user);
|