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422 lines
10 KiB
422 lines
10 KiB
/*
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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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* IP/TCP/UDP checksumming routines
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*
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* Authors: Jorge Cwik, <jorge@laser.satlink.net>
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* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
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* Tom May, <ftom@netcom.com>
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* Andreas Schwab, <schwab@issan.informatik.uni-dortmund.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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* 03/02/96 Jes Sorensen, Andreas Schwab, Roman Hodek:
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* Fixed some nasty bugs, causing some horrible crashes.
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* A: At some points, the sum (%0) was used as
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* length-counter instead of the length counter
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* (%1). Thanks to Roman Hodek for pointing this out.
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* B: GCC seems to mess up if one uses too many
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* data-registers to hold input values and one tries to
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* specify d0 and d1 as scratch registers. Letting gcc
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* choose these registers itself solves the problem.
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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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* 1998/8/31 Andreas Schwab:
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* Zero out rest of buffer on exception in
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* csum_partial_copy_from_user.
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*/
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#include <linux/module.h>
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#include <net/checksum.h>
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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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unsigned int
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csum_partial (const unsigned char *buff, int len, unsigned int sum)
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{
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unsigned long tmp1, tmp2;
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/*
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* Experiments with ethernet and slip connections show that buff
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* is aligned on either a 2-byte or 4-byte boundary.
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*/
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__asm__("movel %2,%3\n\t"
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"btst #1,%3\n\t" /* Check alignment */
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"jeq 2f\n\t"
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"subql #2,%1\n\t" /* buff%4==2: treat first word */
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"jgt 1f\n\t"
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"addql #2,%1\n\t" /* len was == 2, treat only rest */
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"jra 4f\n"
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"1:\t"
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"addw %2@+,%0\n\t" /* add first word to sum */
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"clrl %3\n\t"
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"addxl %3,%0\n" /* add X bit */
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"2:\t"
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/* unrolled loop for the main part: do 8 longs at once */
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"movel %1,%3\n\t" /* save len in tmp1 */
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"lsrl #5,%1\n\t" /* len/32 */
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"jeq 2f\n\t" /* not enough... */
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"subql #1,%1\n"
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"1:\t"
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"movel %2@+,%4\n\t"
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"addxl %4,%0\n\t"
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"movel %2@+,%4\n\t"
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"addxl %4,%0\n\t"
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"movel %2@+,%4\n\t"
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"addxl %4,%0\n\t"
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"movel %2@+,%4\n\t"
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"addxl %4,%0\n\t"
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"movel %2@+,%4\n\t"
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"addxl %4,%0\n\t"
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"movel %2@+,%4\n\t"
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"addxl %4,%0\n\t"
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"movel %2@+,%4\n\t"
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"addxl %4,%0\n\t"
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"movel %2@+,%4\n\t"
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"addxl %4,%0\n\t"
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"dbra %1,1b\n\t"
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"clrl %4\n\t"
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"addxl %4,%0\n\t" /* add X bit */
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"clrw %1\n\t"
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"subql #1,%1\n\t"
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"jcc 1b\n"
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"2:\t"
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"movel %3,%1\n\t" /* restore len from tmp1 */
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"andw #0x1c,%3\n\t" /* number of rest longs */
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"jeq 4f\n\t"
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"lsrw #2,%3\n\t"
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"subqw #1,%3\n"
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"3:\t"
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/* loop for rest longs */
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"movel %2@+,%4\n\t"
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"addxl %4,%0\n\t"
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"dbra %3,3b\n\t"
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"clrl %4\n\t"
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"addxl %4,%0\n" /* add X bit */
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"4:\t"
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/* now check for rest bytes that do not fit into longs */
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"andw #3,%1\n\t"
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"jeq 7f\n\t"
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"clrl %4\n\t" /* clear tmp2 for rest bytes */
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"subqw #2,%1\n\t"
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"jlt 5f\n\t"
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"movew %2@+,%4\n\t" /* have rest >= 2: get word */
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"swap %4\n\t" /* into bits 16..31 */
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"tstw %1\n\t" /* another byte? */
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"jeq 6f\n"
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"5:\t"
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"moveb %2@,%4\n\t" /* have odd rest: get byte */
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"lslw #8,%4\n\t" /* into bits 8..15; 16..31 untouched */
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"6:\t"
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"addl %4,%0\n\t" /* now add rest long to sum */
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"clrl %4\n\t"
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"addxl %4,%0\n" /* add X bit */
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"7:\t"
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: "=d" (sum), "=d" (len), "=a" (buff),
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"=&d" (tmp1), "=&d" (tmp2)
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: "0" (sum), "1" (len), "2" (buff)
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);
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return(sum);
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}
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EXPORT_SYMBOL(csum_partial);
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/*
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* copy from user space while checksumming, with exception handling.
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*/
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unsigned int
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csum_partial_copy_from_user(const unsigned char *src, unsigned char *dst,
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int len, int sum, int *csum_err)
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{
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/*
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* GCC doesn't like more than 10 operands for the asm
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* statements so we have to use tmp2 for the error
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* code.
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*/
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unsigned long tmp1, tmp2;
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__asm__("movel %2,%4\n\t"
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"btst #1,%4\n\t" /* Check alignment */
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"jeq 2f\n\t"
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"subql #2,%1\n\t" /* buff%4==2: treat first word */
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"jgt 1f\n\t"
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"addql #2,%1\n\t" /* len was == 2, treat only rest */
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"jra 4f\n"
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"1:\n"
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"10:\t"
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"movesw %2@+,%4\n\t" /* add first word to sum */
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"addw %4,%0\n\t"
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"movew %4,%3@+\n\t"
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"clrl %4\n\t"
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"addxl %4,%0\n" /* add X bit */
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"2:\t"
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/* unrolled loop for the main part: do 8 longs at once */
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"movel %1,%4\n\t" /* save len in tmp1 */
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"lsrl #5,%1\n\t" /* len/32 */
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"jeq 2f\n\t" /* not enough... */
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"subql #1,%1\n"
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"1:\n"
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"11:\t"
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"movesl %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"12:\t"
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"movesl %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"13:\t"
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"movesl %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"14:\t"
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"movesl %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"15:\t"
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"movesl %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"16:\t"
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"movesl %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"17:\t"
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"movesl %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"18:\t"
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"movesl %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"dbra %1,1b\n\t"
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"clrl %5\n\t"
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"addxl %5,%0\n\t" /* add X bit */
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"clrw %1\n\t"
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"subql #1,%1\n\t"
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"jcc 1b\n"
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"2:\t"
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"movel %4,%1\n\t" /* restore len from tmp1 */
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"andw #0x1c,%4\n\t" /* number of rest longs */
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"jeq 4f\n\t"
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"lsrw #2,%4\n\t"
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"subqw #1,%4\n"
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"3:\n"
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/* loop for rest longs */
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"19:\t"
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"movesl %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"dbra %4,3b\n\t"
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"clrl %5\n\t"
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"addxl %5,%0\n" /* add X bit */
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"4:\t"
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/* now check for rest bytes that do not fit into longs */
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"andw #3,%1\n\t"
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"jeq 7f\n\t"
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"clrl %5\n\t" /* clear tmp2 for rest bytes */
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"subqw #2,%1\n\t"
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"jlt 5f\n\t"
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"20:\t"
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"movesw %2@+,%5\n\t" /* have rest >= 2: get word */
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"movew %5,%3@+\n\t"
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"swap %5\n\t" /* into bits 16..31 */
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"tstw %1\n\t" /* another byte? */
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"jeq 6f\n"
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"5:\n"
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"21:\t"
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"movesb %2@,%5\n\t" /* have odd rest: get byte */
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"moveb %5,%3@+\n\t"
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"lslw #8,%5\n\t" /* into bits 8..15; 16..31 untouched */
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"6:\t"
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"addl %5,%0\n\t" /* now add rest long to sum */
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"clrl %5\n\t"
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"addxl %5,%0\n\t" /* add X bit */
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"7:\t"
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"clrl %5\n" /* no error - clear return value */
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"8:\n"
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".section .fixup,\"ax\"\n"
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".even\n"
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/* If any exception occurs zero out the rest.
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Similarities with the code above are intentional :-) */
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"90:\t"
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"clrw %3@+\n\t"
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"movel %1,%4\n\t"
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"lsrl #5,%1\n\t"
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"jeq 1f\n\t"
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"subql #1,%1\n"
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"91:\t"
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"clrl %3@+\n"
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"92:\t"
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"clrl %3@+\n"
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"93:\t"
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"clrl %3@+\n"
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"94:\t"
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"clrl %3@+\n"
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"95:\t"
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"clrl %3@+\n"
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"96:\t"
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"clrl %3@+\n"
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"97:\t"
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"clrl %3@+\n"
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"98:\t"
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"clrl %3@+\n\t"
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"dbra %1,91b\n\t"
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"clrw %1\n\t"
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"subql #1,%1\n\t"
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"jcc 91b\n"
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"1:\t"
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"movel %4,%1\n\t"
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"andw #0x1c,%4\n\t"
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"jeq 1f\n\t"
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"lsrw #2,%4\n\t"
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"subqw #1,%4\n"
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"99:\t"
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"clrl %3@+\n\t"
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"dbra %4,99b\n\t"
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"1:\t"
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"andw #3,%1\n\t"
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"jeq 9f\n"
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"100:\t"
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"clrw %3@+\n\t"
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"tstw %1\n\t"
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"jeq 9f\n"
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"101:\t"
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"clrb %3@+\n"
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"9:\t"
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#define STR(X) STR1(X)
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#define STR1(X) #X
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"moveq #-" STR(EFAULT) ",%5\n\t"
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"jra 8b\n"
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".previous\n"
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".section __ex_table,\"a\"\n"
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".long 10b,90b\n"
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".long 11b,91b\n"
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".long 12b,92b\n"
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".long 13b,93b\n"
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".long 14b,94b\n"
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".long 15b,95b\n"
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".long 16b,96b\n"
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".long 17b,97b\n"
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".long 18b,98b\n"
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".long 19b,99b\n"
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".long 20b,100b\n"
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".long 21b,101b\n"
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".previous"
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: "=d" (sum), "=d" (len), "=a" (src), "=a" (dst),
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"=&d" (tmp1), "=d" (tmp2)
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: "0" (sum), "1" (len), "2" (src), "3" (dst)
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);
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*csum_err = tmp2;
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return(sum);
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}
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/*
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* copy from kernel space while checksumming, otherwise like csum_partial
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*/
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unsigned int
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csum_partial_copy_nocheck(const unsigned char *src, unsigned char *dst, int len, int sum)
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{
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unsigned long tmp1, tmp2;
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__asm__("movel %2,%4\n\t"
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"btst #1,%4\n\t" /* Check alignment */
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"jeq 2f\n\t"
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"subql #2,%1\n\t" /* buff%4==2: treat first word */
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"jgt 1f\n\t"
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"addql #2,%1\n\t" /* len was == 2, treat only rest */
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"jra 4f\n"
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"1:\t"
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"movew %2@+,%4\n\t" /* add first word to sum */
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"addw %4,%0\n\t"
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"movew %4,%3@+\n\t"
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"clrl %4\n\t"
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"addxl %4,%0\n" /* add X bit */
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"2:\t"
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/* unrolled loop for the main part: do 8 longs at once */
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"movel %1,%4\n\t" /* save len in tmp1 */
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"lsrl #5,%1\n\t" /* len/32 */
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"jeq 2f\n\t" /* not enough... */
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"subql #1,%1\n"
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"1:\t"
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"movel %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"movel %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"movel %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"movel %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"movel %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"movel %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"movel %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"movel %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"dbra %1,1b\n\t"
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"clrl %5\n\t"
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"addxl %5,%0\n\t" /* add X bit */
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"clrw %1\n\t"
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"subql #1,%1\n\t"
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"jcc 1b\n"
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"2:\t"
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"movel %4,%1\n\t" /* restore len from tmp1 */
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"andw #0x1c,%4\n\t" /* number of rest longs */
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"jeq 4f\n\t"
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"lsrw #2,%4\n\t"
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"subqw #1,%4\n"
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"3:\t"
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/* loop for rest longs */
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"movel %2@+,%5\n\t"
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"addxl %5,%0\n\t"
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"movel %5,%3@+\n\t"
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"dbra %4,3b\n\t"
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"clrl %5\n\t"
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"addxl %5,%0\n" /* add X bit */
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"4:\t"
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/* now check for rest bytes that do not fit into longs */
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"andw #3,%1\n\t"
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"jeq 7f\n\t"
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"clrl %5\n\t" /* clear tmp2 for rest bytes */
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"subqw #2,%1\n\t"
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"jlt 5f\n\t"
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"movew %2@+,%5\n\t" /* have rest >= 2: get word */
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"movew %5,%3@+\n\t"
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"swap %5\n\t" /* into bits 16..31 */
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"tstw %1\n\t" /* another byte? */
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"jeq 6f\n"
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"5:\t"
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"moveb %2@,%5\n\t" /* have odd rest: get byte */
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"moveb %5,%3@+\n\t"
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"lslw #8,%5\n" /* into bits 8..15; 16..31 untouched */
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"6:\t"
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"addl %5,%0\n\t" /* now add rest long to sum */
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"clrl %5\n\t"
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"addxl %5,%0\n" /* add X bit */
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"7:\t"
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: "=d" (sum), "=d" (len), "=a" (src), "=a" (dst),
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"=&d" (tmp1), "=&d" (tmp2)
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: "0" (sum), "1" (len), "2" (src), "3" (dst)
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);
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return(sum);
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}
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