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