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csum_partial() is a generic function which is not optimised for small fixed length calculations, and its use requires to store "from" and "to" values in memory while we already have them available in registers. This also has impact, especially on RISC processors. In the same spirit as the change done by Eric Dumazet on csum_replace2(), this patch rewrites inet_proto_csum_replace4() taking into account RFC1624. I spotted during a NATted tcp transfert that csum_partial() is one of top 5 consuming functions (around 8%), and the second user of csum_partial() is inet_proto_csum_replace4(). I have proposed the same modification to inet_proto_csum_replace4() in another patch. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
155 lines
3.9 KiB
C
155 lines
3.9 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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* Checksumming functions for IP, TCP, UDP and so on
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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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* Borrows very liberally from tcp.c and ip.c, see those
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* files 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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#ifndef _CHECKSUM_H
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#define _CHECKSUM_H
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#include <linux/errno.h>
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#include <asm/types.h>
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#include <asm/byteorder.h>
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#include <asm/uaccess.h>
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#include <asm/checksum.h>
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#ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
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static inline
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__wsum csum_and_copy_from_user (const void __user *src, void *dst,
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int len, __wsum sum, int *err_ptr)
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{
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if (access_ok(VERIFY_READ, src, len))
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return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
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if (len)
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*err_ptr = -EFAULT;
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return sum;
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}
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#endif
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#ifndef HAVE_CSUM_COPY_USER
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static __inline__ __wsum csum_and_copy_to_user
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(const void *src, void __user *dst, int len, __wsum sum, int *err_ptr)
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{
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sum = csum_partial(src, len, sum);
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if (access_ok(VERIFY_WRITE, dst, len)) {
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if (copy_to_user(dst, src, len) == 0)
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return sum;
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}
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if (len)
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*err_ptr = -EFAULT;
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return (__force __wsum)-1; /* invalid checksum */
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}
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#endif
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#ifndef HAVE_ARCH_CSUM_ADD
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static inline __wsum csum_add(__wsum csum, __wsum addend)
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{
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u32 res = (__force u32)csum;
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res += (__force u32)addend;
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return (__force __wsum)(res + (res < (__force u32)addend));
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}
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#endif
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static inline __wsum csum_sub(__wsum csum, __wsum addend)
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{
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return csum_add(csum, ~addend);
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}
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static inline __sum16 csum16_add(__sum16 csum, __be16 addend)
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{
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u16 res = (__force u16)csum;
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res += (__force u16)addend;
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return (__force __sum16)(res + (res < (__force u16)addend));
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}
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static inline __sum16 csum16_sub(__sum16 csum, __be16 addend)
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{
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return csum16_add(csum, ~addend);
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}
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static inline __wsum
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csum_block_add(__wsum csum, __wsum csum2, int offset)
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{
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u32 sum = (__force u32)csum2;
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if (offset&1)
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sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
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return csum_add(csum, (__force __wsum)sum);
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}
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static inline __wsum
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csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
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{
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return csum_block_add(csum, csum2, offset);
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}
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static inline __wsum
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csum_block_sub(__wsum csum, __wsum csum2, int offset)
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{
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u32 sum = (__force u32)csum2;
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if (offset&1)
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sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
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return csum_sub(csum, (__force __wsum)sum);
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}
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static inline __wsum csum_unfold(__sum16 n)
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{
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return (__force __wsum)n;
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}
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static inline __wsum csum_partial_ext(const void *buff, int len, __wsum sum)
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{
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return csum_partial(buff, len, sum);
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}
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#define CSUM_MANGLED_0 ((__force __sum16)0xffff)
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static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
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{
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*sum = csum_fold(csum_add(csum_sub(~csum_unfold(*sum), from), to));
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}
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/* Implements RFC 1624 (Incremental Internet Checksum)
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* 3. Discussion states :
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* HC' = ~(~HC + ~m + m')
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* m : old value of a 16bit field
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* m' : new value of a 16bit field
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*/
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static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
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{
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*sum = ~csum16_add(csum16_sub(~(*sum), old), new);
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}
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struct sk_buff;
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void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
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__be32 from, __be32 to, int pseudohdr);
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void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
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const __be32 *from, const __be32 *to,
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int pseudohdr);
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static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
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__be16 from, __be16 to,
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int pseudohdr)
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{
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inet_proto_csum_replace4(sum, skb, (__force __be32)from,
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(__force __be32)to, pseudohdr);
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}
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#endif
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