From e6d17f2612e4274d79de87b5d6c0cb992c1aa888 Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Sat, 3 Apr 2021 17:57:16 -0400 Subject: [PATCH] Tag short packets as unlikely --- xdp.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) diff --git a/xdp.c b/xdp.c index 8623af4..26a1231 100644 --- a/xdp.c +++ b/xdp.c @@ -108,6 +108,9 @@ struct tcphdr { // Note rules.h may also define PARSE_IHL #include "rules.h" +#define unlikely(a) __builtin_expect(a, 0) +#define likely(a) __builtin_expect(a, 1) + #ifdef TEST // 64 bit version of xdp_md for testing struct xdp_md { @@ -136,18 +139,18 @@ int xdp_drop_prog(struct xdp_md *ctx) unsigned short eth_proto; { - if ((void*)(size_t)ctx->data + sizeof(struct ethhdr) > data_end) + if (unlikely((void*)(size_t)ctx->data + sizeof(struct ethhdr) > data_end)) return XDP_DROP; const struct ethhdr *const eth = (void*)(size_t)ctx->data; #ifdef PARSE_8021Q - if (eth->h_proto == BE16(ETH_P_8021Q)) { - if ((void*)(size_t)ctx->data + sizeof(struct ethhdr_vlan) > data_end) + if (likely(eth->h_proto == BE16(ETH_P_8021Q))) { + if (unlikely((void*)(size_t)ctx->data + sizeof(struct ethhdr_vlan) > data_end)) return XDP_DROP; const struct ethhdr_vlan *const eth_vlan = (void*)(size_t)ctx->data; #ifdef REQ_8021Q - if ((eth_vlan->tci & BE16(0xfff)) != BE16(REQ_8021Q)) + if (unlikely((eth_vlan->tci & BE16(0xfff)) != BE16(REQ_8021Q))) return XDP_DROP; #endif @@ -176,32 +179,32 @@ int xdp_drop_prog(struct xdp_md *ctx) const struct ip6hdr *ip6 = NULL; const void *l4hdr = NULL; if (eth_proto == BE16(ETH_P_IP)) { - if (pktdata + sizeof(struct iphdr) > data_end) + if (unlikely(pktdata + sizeof(struct iphdr) > data_end)) return XDP_DROP; ip = (struct iphdr*) pktdata; #ifdef PARSE_IHL - if (ip->ihl < 5) return XDP_DROP; + if (unlikely(ip->ihl < 5)) return XDP_DROP; l4hdr = pktdata + ip->ihl * 4; #else if (ip->ihl != 5) return XDP_DROP; l4hdr = pktdata + 5*4; #endif if (ip->protocol == IP_PROTO_TCP) { - if (l4hdr + sizeof(struct tcphdr) > data_end) + if (unlikely(l4hdr + sizeof(struct tcphdr) > data_end)) return XDP_DROP; tcp = (struct tcphdr*) l4hdr; } else if (ip->protocol == IP_PROTO_UDP) { - if (l4hdr + sizeof(struct udphdr) > data_end) + if (unlikely(l4hdr + sizeof(struct udphdr) > data_end)) return XDP_DROP; udp = (struct udphdr*) l4hdr; } else if (ip->protocol == IP_PROTO_ICMP) { - if (l4hdr + sizeof(struct icmphdr) > data_end) + if (unlikely(l4hdr + sizeof(struct icmphdr) > data_end)) return XDP_DROP; icmp = (struct icmphdr*) l4hdr; } } else if (eth_proto == BE16(ETH_P_IPV6)) { - if (pktdata + sizeof(struct ip6hdr) > data_end) + if (unlikely(pktdata + sizeof(struct ip6hdr) > data_end)) return XDP_DROP; ip6 = (struct ip6hdr*) pktdata; @@ -209,7 +212,7 @@ int xdp_drop_prog(struct xdp_md *ctx) uint8_t v6nexthdr; if (ip6->nexthdr == IP6_PROTO_FRAG) { - if (l4hdr + sizeof(struct ip6_fraghdr) > data_end) + if (unlikely(l4hdr + sizeof(struct ip6_fraghdr) > data_end)) return XDP_DROP; frag6 = (struct ip6_fraghdr*) l4hdr; l4hdr = l4hdr + sizeof(struct ip6_fraghdr); @@ -219,15 +222,15 @@ int xdp_drop_prog(struct xdp_md *ctx) } if (v6nexthdr == IP_PROTO_TCP) { - if (l4hdr + sizeof(struct tcphdr) > data_end) + if (unlikely(l4hdr + sizeof(struct tcphdr) > data_end)) return XDP_DROP; tcp = (struct tcphdr*) l4hdr; } else if (v6nexthdr == IP_PROTO_UDP) { - if (l4hdr + sizeof(struct udphdr) > data_end) + if (unlikely(l4hdr + sizeof(struct udphdr) > data_end)) return XDP_DROP; udp = (struct udphdr*) l4hdr; } else if (v6nexthdr == IP6_PROTO_ICMPV6) { - if (l4hdr + sizeof(struct icmp6hdr) > data_end) + if (unlikely(l4hdr + sizeof(struct icmp6hdr) > data_end)) return XDP_DROP; icmpv6 = (struct icmp6hdr*) l4hdr; } -- 2.30.2