kernel-fxtec-pro1x/include/linux/etherdevice.h
Eric Dumazet 1f87e235e6 eth: Declare an optimized compare_ether_addr_64bits() function
Linus mentioned we could try to perform long word operations, even
on potentially unaligned addresses, on x86 at least. David mentioned
the HAVE_EFFICIENT_UNALIGNED_ACCESS test to handle this on all
arches that have efficient unailgned accesses.

I tried this idea and got nice assembly on 32 bits:

158:   33 82 38 01 00 00       xor    0x138(%edx),%eax
15e:   33 8a 34 01 00 00       xor    0x134(%edx),%ecx
164:   c1 e0 10                shl    $0x10,%eax
167:   09 c1                   or     %eax,%ecx
169:   74 0b                   je     176 <eth_type_trans+0x87>

And very nice assembly on 64 bits of course (one xor, one shl)

Nice oprofile improvement in eth_type_trans(), 0.17 % instead of 0.41 %,
expected since we remove 8 instructions on a fast path.

This patch implements a compare_ether_addr_64bits() function, that
uses the CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS ifdef to efficiently
perform the 6 bytes comparison on all capable arches.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-23 23:24:32 -08:00

187 lines
5.9 KiB
C

/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. NET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Definitions for the Ethernet handlers.
*
* Version: @(#)eth.h 1.0.4 05/13/93
*
* Authors: Ross Biro
* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
*
* Relocated to include/linux where it belongs by Alan Cox
* <gw4pts@gw4pts.ampr.org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* WARNING: This move may well be temporary. This file will get merged with others RSN.
*
*/
#ifndef _LINUX_ETHERDEVICE_H
#define _LINUX_ETHERDEVICE_H
#include <linux/if_ether.h>
#include <linux/netdevice.h>
#include <linux/random.h>
#include <asm/unaligned.h>
#ifdef __KERNEL__
extern __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev);
extern const struct header_ops eth_header_ops;
extern int eth_header(struct sk_buff *skb, struct net_device *dev,
unsigned short type,
const void *daddr, const void *saddr, unsigned len);
extern int eth_rebuild_header(struct sk_buff *skb);
extern int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr);
extern int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh);
extern void eth_header_cache_update(struct hh_cache *hh,
const struct net_device *dev,
const unsigned char *haddr);
extern int eth_mac_addr(struct net_device *dev, void *p);
extern int eth_change_mtu(struct net_device *dev, int new_mtu);
extern int eth_validate_addr(struct net_device *dev);
extern struct net_device *alloc_etherdev_mq(int sizeof_priv, unsigned int queue_count);
#define alloc_etherdev(sizeof_priv) alloc_etherdev_mq(sizeof_priv, 1)
/**
* is_zero_ether_addr - Determine if give Ethernet address is all zeros.
* @addr: Pointer to a six-byte array containing the Ethernet address
*
* Return true if the address is all zeroes.
*/
static inline int is_zero_ether_addr(const u8 *addr)
{
return !(addr[0] | addr[1] | addr[2] | addr[3] | addr[4] | addr[5]);
}
/**
* is_multicast_ether_addr - Determine if the Ethernet address is a multicast.
* @addr: Pointer to a six-byte array containing the Ethernet address
*
* Return true if the address is a multicast address.
* By definition the broadcast address is also a multicast address.
*/
static inline int is_multicast_ether_addr(const u8 *addr)
{
return (0x01 & addr[0]);
}
/**
* is_local_ether_addr - Determine if the Ethernet address is locally-assigned one (IEEE 802).
* @addr: Pointer to a six-byte array containing the Ethernet address
*
* Return true if the address is a local address.
*/
static inline int is_local_ether_addr(const u8 *addr)
{
return (0x02 & addr[0]);
}
/**
* is_broadcast_ether_addr - Determine if the Ethernet address is broadcast
* @addr: Pointer to a six-byte array containing the Ethernet address
*
* Return true if the address is the broadcast address.
*/
static inline int is_broadcast_ether_addr(const u8 *addr)
{
return (addr[0] & addr[1] & addr[2] & addr[3] & addr[4] & addr[5]) == 0xff;
}
/**
* is_valid_ether_addr - Determine if the given Ethernet address is valid
* @addr: Pointer to a six-byte array containing the Ethernet address
*
* Check that the Ethernet address (MAC) is not 00:00:00:00:00:00, is not
* a multicast address, and is not FF:FF:FF:FF:FF:FF.
*
* Return true if the address is valid.
*/
static inline int is_valid_ether_addr(const u8 *addr)
{
/* FF:FF:FF:FF:FF:FF is a multicast address so we don't need to
* explicitly check for it here. */
return !is_multicast_ether_addr(addr) && !is_zero_ether_addr(addr);
}
/**
* random_ether_addr - Generate software assigned random Ethernet address
* @addr: Pointer to a six-byte array containing the Ethernet address
*
* Generate a random Ethernet address (MAC) that is not multicast
* and has the local assigned bit set.
*/
static inline void random_ether_addr(u8 *addr)
{
get_random_bytes (addr, ETH_ALEN);
addr [0] &= 0xfe; /* clear multicast bit */
addr [0] |= 0x02; /* set local assignment bit (IEEE802) */
}
/**
* compare_ether_addr - Compare two Ethernet addresses
* @addr1: Pointer to a six-byte array containing the Ethernet address
* @addr2: Pointer other six-byte array containing the Ethernet address
*
* Compare two ethernet addresses, returns 0 if equal
*/
static inline unsigned compare_ether_addr(const u8 *addr1, const u8 *addr2)
{
const u16 *a = (const u16 *) addr1;
const u16 *b = (const u16 *) addr2;
BUILD_BUG_ON(ETH_ALEN != 6);
return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | (a[2] ^ b[2])) != 0;
}
static inline unsigned long zap_last_2bytes(unsigned long value)
{
#ifdef __BIG_ENDIAN
return value >> 16;
#else
return value << 16;
#endif
}
/**
* compare_ether_addr_64bits - Compare two Ethernet addresses
* @addr1: Pointer to an array of 8 bytes
* @addr2: Pointer to an other array of 8 bytes
*
* Compare two ethernet addresses, returns 0 if equal.
* Same result than "memcmp(addr1, addr2, ETH_ALEN)" but without conditional
* branches, and possibly long word memory accesses on CPU allowing cheap
* unaligned memory reads.
* arrays = { byte1, byte2, byte3, byte4, byte6, byte7, pad1, pad2}
*
* Please note that alignment of addr1 & addr2 is only guaranted to be 16 bits.
*/
static inline unsigned compare_ether_addr_64bits(const u8 addr1[6+2],
const u8 addr2[6+2])
{
#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
unsigned long fold = ((*(unsigned long *)addr1) ^
(*(unsigned long *)addr2));
if (sizeof(fold) == 8)
return zap_last_2bytes(fold) != 0;
fold |= zap_last_2bytes((*(unsigned long *)(addr1 + 4)) ^
(*(unsigned long *)(addr2 + 4)));
return fold != 0;
#else
return compare_ether_addr(addr1, addr2);
#endif
}
#endif /* __KERNEL__ */
#endif /* _LINUX_ETHERDEVICE_H */