ipv4: use a 64bit load/store in output path
gcc compiler is smart enough to use a single load/store if we memcpy(dptr, sptr, 8) on x86_64, regardless of CONFIG_CC_OPTIMIZE_FOR_SIZE In IP header, daddr immediately follows saddr, this wont change in the future. We only need to make sure our flowi4 (saddr,daddr) fields wont break the rule. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -59,8 +59,11 @@ struct flowi4 {
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#define flowi4_proto __fl_common.flowic_proto
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#define flowi4_flags __fl_common.flowic_flags
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#define flowi4_secid __fl_common.flowic_secid
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__be32 daddr;
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/* (saddr,daddr) must be grouped, same order as in IP header */
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__be32 saddr;
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__be32 daddr;
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union flowi_uli uli;
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#define fl4_sport uli.ports.sport
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#define fl4_dport uli.ports.dport
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@ -319,6 +319,20 @@ int ip_output(struct sk_buff *skb)
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!(IPCB(skb)->flags & IPSKB_REROUTED));
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}
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/*
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* copy saddr and daddr, possibly using 64bit load/stores
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* Equivalent to :
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* iph->saddr = fl4->saddr;
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* iph->daddr = fl4->daddr;
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*/
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static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
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{
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BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
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offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
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memcpy(&iph->saddr, &fl4->saddr,
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sizeof(fl4->saddr) + sizeof(fl4->daddr));
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}
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int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl)
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{
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struct sock *sk = skb->sk;
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@ -381,8 +395,8 @@ packet_routed:
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iph->frag_off = 0;
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iph->ttl = ip_select_ttl(inet, &rt->dst);
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iph->protocol = sk->sk_protocol;
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iph->saddr = fl4->saddr;
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iph->daddr = fl4->daddr;
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ip_copy_addrs(iph, fl4);
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/* Transport layer set skb->h.foo itself. */
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if (inet_opt && inet_opt->opt.optlen) {
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@ -1337,8 +1351,7 @@ struct sk_buff *__ip_make_skb(struct sock *sk,
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ip_select_ident(iph, &rt->dst, sk);
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iph->ttl = ttl;
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iph->protocol = sk->sk_protocol;
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iph->saddr = fl4->saddr;
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iph->daddr = fl4->daddr;
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ip_copy_addrs(iph, fl4);
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if (opt) {
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iph->ihl += opt->optlen>>2;
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