ar71xx: add some hacks to work around the misalignment in IP packets received on AR71xx and AR91xx ethernet MACs

decreases CPU load with the default firewall for routing 95 mbit/s from 78% to 55%

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@27878 3c298f89-4303-0410-b956-a3cf2f4a3e73

target/linux/ar71xx/patches-2.6.39/910-unaligned_access_hacks.patch

@@ -0,0 +1,117 @@
+--- a/arch/mips/include/asm/checksum.h
++++ b/arch/mips/include/asm/checksum.h
+@@ -12,6 +12,7 @@
+ #define _ASM_CHECKSUM_H
+ 
+ #include <linux/in6.h>
++#include <linux/unaligned/packed_struct.h>
+ 
+ #include <asm/uaccess.h>
+ 
+@@ -104,26 +105,30 @@ static inline __sum16 ip_fast_csum(const
+ 	const unsigned int *stop = word + ihl;
+ 	unsigned int csum;
+ 	int carry;
++	unsigned int w;
+ 
+-	csum = word[0];
+-	csum += word[1];
+-	carry = (csum < word[1]);
++	csum = __get_unaligned_cpu32(word++);
++
++	w = __get_unaligned_cpu32(word++);
++	csum += w;
++	carry = (csum < w);
+ 	csum += carry;
+ 
+-	csum += word[2];
+-	carry = (csum < word[2]);
++	w = __get_unaligned_cpu32(word++);
++	csum += w;
++	carry = (csum < w);
+ 	csum += carry;
+ 
+-	csum += word[3];
+-	carry = (csum < word[3]);
++	w = __get_unaligned_cpu32(word++);
++	csum += w;
++	carry = (csum < w);
+ 	csum += carry;
+ 
+-	word += 4;
+ 	do {
+-		csum += *word;
+-		carry = (csum < *word);
++		w = __get_unaligned_cpu32(word++);
++		csum += w;
++		carry = (csum < w);
+ 		csum += carry;
+-		word++;
+ 	} while (word != stop);
+ 
+ 	return csum_fold(csum);
+--- a/include/linux/ip.h
++++ b/include/linux/ip.h
+@@ -102,7 +102,7 @@ struct iphdr {
+ 	__be32	saddr;
+ 	__be32	daddr;
+ 	/*The options start here. */
+-};
++} __packed;
+ 
+ #ifdef __KERNEL__
+ #include <linux/skbuff.h>
+--- a/include/linux/ipv6.h
++++ b/include/linux/ipv6.h
+@@ -126,7 +126,7 @@ struct ipv6hdr {
+ 
+ 	struct	in6_addr	saddr;
+ 	struct	in6_addr	daddr;
+-};
++} __packed;
+ 
+ #ifdef __KERNEL__
+ /*
+--- a/include/linux/tcp.h
++++ b/include/linux/tcp.h
+@@ -54,7 +54,7 @@ struct tcphdr {
+ 	__be16	window;
+ 	__sum16	check;
+ 	__be16	urg_ptr;
+-};
++} __packed;
+ 
+ /*
+  *	The union cast uses a gcc extension to avoid aliasing problems
+--- a/include/linux/udp.h
++++ b/include/linux/udp.h
+@@ -24,7 +24,7 @@ struct udphdr {
+ 	__be16	dest;
+ 	__be16	len;
+ 	__sum16	check;
+-};
++} __packed;
+ 
+ /* UDP socket options */
+ #define UDP_CORK	1	/* Never send partially complete segments */
+--- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
++++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
+@@ -14,6 +14,7 @@
+ #include <linux/skbuff.h>
+ #include <linux/icmp.h>
+ #include <linux/sysctl.h>
++#include <linux/unaligned/packed_struct.h>
+ #include <net/route.h>
+ #include <net/ip.h>
+ 
+@@ -44,8 +45,8 @@ static bool ipv4_pkt_to_tuple(const stru
+ 	if (ap == NULL)
+ 		return false;
+ 
+-	tuple->src.u3.ip = ap[0];
+-	tuple->dst.u3.ip = ap[1];
++	tuple->src.u3.ip = __get_unaligned_cpu32(ap++);
++	tuple->dst.u3.ip = __get_unaligned_cpu32(ap);
+ 
+ 	return true;
+ }