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d5de6c2a5f
checksumming. These bugs could possibly cause bad code to be generated at elevated optimization levels. First, eliminate the use of preprocessor magic to form the address fields of asm instructions. It hid the actual addresses being referenced from the compiler. Without knowledge of all the data dependencies, the compiler might possibly use optimizations which would result in incorrect code. Use "__asm __volatile" rather than "__asm" for instruction sequences that pass information through the condition codes (the carry bit, in this case). Without __volatile, the compiler might add unrelated code between consecutive __asm instructions, modifying the condition codes. I have seen GCC insert stack pointer adjustments in this way, for example. Unfortunately, GCC doesn't provide a way to specify dependencies on the condition codes. You can specify that they are clobbered, but not that you are going to use them as input. Finally, simplify the LOAD macro. This macro is used as a poor man's prefetch. The simpler version gives the compiler more leeway about just how it performs the prefetch. MFC after: 1 week
133 lines
4.1 KiB
C
133 lines
4.1 KiB
C
/*-
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from tahoe: in_cksum.c 1.2 86/01/05
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* from: @(#)in_cksum.c 1.3 (Berkeley) 1/19/91
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* from: Id: in_cksum.c,v 1.8 1995/12/03 18:35:19 bde Exp
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* $FreeBSD$
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*/
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#ifndef _MACHINE_IN_CKSUM_H_
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#define _MACHINE_IN_CKSUM_H_ 1
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/*
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* MP safe (alfred)
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*/
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#include <sys/cdefs.h>
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#define in_cksum(m, len) in_cksum_skip(m, len, 0)
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/*
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* It it useful to have an Internet checksum routine which is inlineable
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* and optimized specifically for the task of computing IP header checksums
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* in the normal case (where there are no options and the header length is
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* therefore always exactly five 32-bit words.
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*/
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#ifdef __GNUC__
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static __inline u_int
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in_cksum_hdr(const struct ip *ip)
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{
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register u_int sum = 0;
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/* __volatile is necessary here because the condition codes are used. */
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#define ADD(n) __asm __volatile ("addl %1, %0" : "+r" (sum) : \
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"g" (((const u_int32_t *)ip)[n / 4]))
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#define ADDC(n) __asm __volatile ("adcl %1, %0" : "+r" (sum) : \
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"g" (((const u_int32_t *)ip)[n / 4]))
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#define MOP __asm __volatile ("adcl $0, %0" : "+r" (sum))
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ADD(0);
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ADDC(4);
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ADDC(8);
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ADDC(12);
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ADDC(16);
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MOP;
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#undef ADD
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#undef ADDC
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#undef MOP
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sum = (sum & 0xffff) + (sum >> 16);
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if (sum > 0xffff)
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sum -= 0xffff;
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return ~sum & 0xffff;
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}
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static __inline void
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in_cksum_update(struct ip *ip)
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{
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int __tmpsum;
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__tmpsum = (int)ntohs(ip->ip_sum) + 256;
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ip->ip_sum = htons(__tmpsum + (__tmpsum >> 16));
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}
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static __inline u_short
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in_addword(u_short sum, u_short b)
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{
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/* __volatile is necessary because the condition codes are used. */
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__asm __volatile ("addw %1, %0" : "+r" (sum) : "r" (b));
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__asm __volatile ("adcw $0, %0" : "+r" (sum));
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return (sum);
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}
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static __inline u_short
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in_pseudo(u_int sum, u_int b, u_int c)
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{
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/* __volatile is necessary because the condition codes are used. */
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__asm __volatile ("addl %1, %0" : "+r" (sum) : "g" (b));
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__asm __volatile ("adcl %1, %0" : "+r" (sum) : "g" (c));
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__asm __volatile ("adcl $0, %0" : "+r" (sum));
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sum = (sum & 0xffff) + (sum >> 16);
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if (sum > 0xffff)
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sum -= 0xffff;
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return (sum);
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}
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#else
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u_int in_cksum_hdr(const struct ip *);
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#define in_cksum_update(ip) \
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do { \
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int __tmpsum; \
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__tmpsum = (int)ntohs(ip->ip_sum) + 256; \
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ip->ip_sum = htons(__tmpsum + (__tmpsum >> 16)); \
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} while(0)
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#endif
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#ifdef _KERNEL
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u_short in_cksum_skip(struct mbuf *m, int len, int skip);
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#endif /* _KERNEL */
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#endif /* _MACHINE_IN_CKSUM_H_ */
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