xref: /freebsd-11-stable/sys/netpfil/pf/in4_cksum.c

/*	$FreeBSD: head/sys/contrib/pf/netinet/in4_cksum.c 126261 2004-02-26 02:34:12Z mlaier $	*/
/*	$OpenBSD: in4_cksum.c,v 1.7 2003/06/02 23:28:13 millert Exp $	*/
/*	$KAME: in4_cksum.c,v 1.10 2001/11/30 10:06:15 itojun Exp $	*/
/*	$NetBSD: in_cksum.c,v 1.13 1996/10/13 02:03:03 christos Exp $	*/

/*
 * Copyright (C) 1999 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright (c) 1988, 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)in_cksum.c	8.1 (Berkeley) 6/10/93
 */

#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/systm.h>
#include <sys/socket.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>

#if defined(__FreeBSD__) && defined(__i386__)
/*
 * Copied from FreeBSD 5.0 sys/i386/i386/in_cksum.c
 * XXX
 * Currently support I386 processor only.
 * In the long run, we need an optimized cksum routines for each Tier1
 * architecture. Due to the lack of available hardware except I386 I
 * can't support other processors now. For those users which use Sparc64,
 * Alpha processors can use more optimized version in FreeBSD.
 * See sys/$ARCH/$ARCH/in_cksum.c where $ARCH=`uname -p`
 */

/*
 * These asm statements require __volatile because they pass information
 * via the condition codes.  GCC does not currently provide a way to specify
 * the condition codes as an input or output operand.
 *
 * The LOAD macro below is effectively a prefetch into cache.  GCC will
 * load the value into a register but will not use it.  Since modern CPUs
 * reorder operations, this will generally take place in parallel with
 * other calculations.
 */
#define ADD(n)	__asm __volatile \
		("addl %1, %0" : "+r" (sum) : \
		"g" (((const u_int32_t *)w)[n / 4]))
#define ADDC(n)	__asm __volatile \
		("adcl %1, %0" : "+r" (sum) : \
		"g" (((const u_int32_t *)w)[n / 4]))
#define LOAD(n)	__asm __volatile \
		("" : : "r" (((const u_int32_t *)w)[n / 4]))
#define MOP	__asm __volatile \
		("adcl         $0, %0" : "+r" (sum))
#endif
/*
 * Checksum routine for Internet Protocol family headers (Portable Version).
 * This is only for IPv4 pseudo header checksum.
 * No need to clear non-pseudo-header fields in IPv4 header.
 * len is for actual payload size, and does not include IPv4 header and
 * skipped header chain (off + len should be equal to the whole packet).
 *
 * This routine is very heavily used in the network
 * code and should be modified for each CPU to be as fast as possible.
 */

#define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}

#if defined(__FreeBSD__)
int
in4_cksum(struct mbuf *m, u_int8_t nxt, int off, int len);
#endif

int
in4_cksum(m, nxt, off, len)
	struct mbuf *m;
	u_int8_t nxt;
	int off, len;
{
	u_int16_t *w;
	int sum = 0;
	int mlen = 0;
	int byte_swapped = 0;
	union {
		struct ipovly ipov;
		u_int16_t w[10];
	} u;
	union {
		u_int8_t  c[2];
		u_int16_t s;
	} s_util;
	union {
		u_int16_t s[2];
		u_int32_t l;
	} l_util;

	if (nxt != 0) {
		/* pseudo header */
		if (off < sizeof(struct ipovly))
			panic("in4_cksum: offset too short");
		if (m->m_len < sizeof(struct ip))
			panic("in4_cksum: bad mbuf chain");
		bzero(&u.ipov, sizeof(u.ipov));
		u.ipov.ih_len = htons(len);
		u.ipov.ih_pr = nxt;
		u.ipov.ih_src = mtod(m, struct ip *)->ip_src;
		u.ipov.ih_dst = mtod(m, struct ip *)->ip_dst;
		w = u.w;
		/* assumes sizeof(ipov) == 20 */
		sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4];
		sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9];
	}

	/* skip unnecessary part */
	while (m && off > 0) {
		if (m->m_len > off)
			break;
		off -= m->m_len;
		m = m->m_next;
	}

	for (;m && len; m = m->m_next) {
		if (m->m_len == 0)
			continue;
		w = (u_int16_t *)(mtod(m, caddr_t) + off);
		if (mlen == -1) {
			/*
			 * The first byte of this mbuf is the continuation
			 * of a word spanning between this mbuf and the
			 * last mbuf.
			 *
			 * s_util.c[0] is already saved when scanning previous
			 * mbuf.
			 */
			s_util.c[1] = *(u_int8_t *)w;
			sum += s_util.s;
			w = (u_int16_t *)((u_int8_t *)w + 1);
			mlen = m->m_len - off - 1;
			len--;
		} else
			mlen = m->m_len - off;
		off = 0;
		if (len < mlen)
			mlen = len;
		len -= mlen;
#if defined(__FreeBSD__) && defined(__i386__)
		/*
		 * Force to long boundary so we do longword aligned
		 * memory operations
		 */
		if (3 & (int) w) {
			REDUCE;
			if ((1 & (int) w) && (mlen > 0)) {
				sum <<= 8;
				s_util.c[0] = *(char *)w;
				w = (u_short *)((char *)w + 1);
				mlen--;
				byte_swapped = 1;
			}
			if ((2 & (int) w) && (mlen >= 2)) {
				sum += *w++;
				mlen -= 2;
			}
		}
		/*
		 * Advance to a 486 cache line boundary.
		 */
		if (4 & (int) w && mlen >= 4) {
			ADD(0);
			MOP;
			w += 2;
			mlen -= 4;
		}
		if (8 & (int) w && mlen >= 8) {
			ADD(0);
			ADDC(4);
			MOP;
			w += 4;
			mlen -= 8;
		}
		/*
		 * Do as much of the checksum as possible 32 bits at at time.
		 * In fact, this loop is unrolled to make overhead from
		 * branches &c small.
		 */
		mlen -= 1;
		while ((mlen -= 32) >= 0) {
			/*
			 * Add with carry 16 words and fold in the last
			 * carry by adding a 0 with carry.
			 *
			 * The early ADD(16) and the LOAD(32) are to load
			 * the next 2 cache lines in advance on 486's.  The
			 * 486 has a penalty of 2 clock cycles for loading
			 * a cache line, plus whatever time the external
			 * memory takes to load the first word(s) addressed.
			 * These penalties are unavoidable.  Subsequent
			 * accesses to a cache line being loaded (and to
			 * other external memory?) are delayed until the
			 * whole load finishes.  These penalties are mostly
			 * avoided by not accessing external memory for
			 * 8 cycles after the ADD(16) and 12 cycles after
			 * the LOAD(32).  The loop terminates when mlen
			 * is initially 33 (not 32) to guaranteed that
			 * the LOAD(32) is within bounds.
			 */
			ADD(16);
			ADDC(0);
			ADDC(4);
			ADDC(8);
			ADDC(12);
			LOAD(32);
			ADDC(20);
			ADDC(24);
			ADDC(28);
			MOP;
			w += 16;
		}
		mlen += 32 + 1;
		if (mlen >= 32) {
			ADD(16);
			ADDC(0);
			ADDC(4);
			ADDC(8);
			ADDC(12);
			ADDC(20);
			ADDC(24);
			ADDC(28);
			MOP;
			w += 16;
			mlen -= 32;
		}
		if (mlen >= 16) {
			ADD(0);
			ADDC(4);
			ADDC(8);
			ADDC(12);
			MOP;
			w += 8;
			mlen -= 16;
		}
		if (mlen >= 8) {
			ADD(0);
			ADDC(4);
			MOP;
			w += 4;
			mlen -= 8;
		}
		if (mlen == 0 && byte_swapped == 0)
			continue;       /* worth 1% maybe ?? */
		REDUCE;
		while ((mlen -= 2) >= 0) {
			sum += *w++;
		}
		if (byte_swapped) {
			REDUCE;
			sum <<= 8;
			byte_swapped = 0;
			if (mlen == -1) {
				s_util.c[1] = *(char *)w;
				sum += s_util.s;
				mlen = 0;
			} else
				mlen = -1;
		} else if (mlen == -1)
			/*
			 * This mbuf has odd number of bytes.
			 * There could be a word split betwen
			 * this mbuf and the next mbuf.
			 * Save the last byte (to prepend to next mbuf).
			 */
			s_util.c[0] = *(char *)w;
#else
		/*
		 * Force to even boundary.
		 */
		if ((1 & (long) w) && (mlen > 0)) {
			REDUCE;
			sum <<= 8;
			s_util.c[0] = *(u_int8_t *)w;
			w = (u_int16_t *)((int8_t *)w + 1);
			mlen--;
			byte_swapped = 1;
		}
		/*
		 * Unroll the loop to make overhead from
		 * branches &c small.
		 */
		while ((mlen -= 32) >= 0) {
			sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
			sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
			sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
			sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
			w += 16;
		}
		mlen += 32;
		while ((mlen -= 8) >= 0) {
			sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
			w += 4;
		}
		mlen += 8;
		if (mlen == 0 && byte_swapped == 0)
			continue;
		REDUCE;
		while ((mlen -= 2) >= 0) {
			sum += *w++;
		}
		if (byte_swapped) {
			REDUCE;
			sum <<= 8;
			byte_swapped = 0;
			if (mlen == -1) {
				s_util.c[1] = *(u_int8_t *)w;
				sum += s_util.s;
				mlen = 0;
			} else
				mlen = -1;
		} else if (mlen == -1)
			s_util.c[0] = *(u_int8_t *)w;
#endif
	}
	if (len)
		printf("cksum4: out of data\n");
	if (mlen == -1) {
		/* The last mbuf has odd # of bytes. Follow the
		   standard (the odd byte may be shifted left by 8 bits
		   or not as determined by endian-ness of the machine) */
		s_util.c[1] = 0;
		sum += s_util.s;
	}
	REDUCE;
	return (~sum & 0xffff);
}