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selftests/bpf: Add XDP load-balancer BPF program
Add the BPF datapath for the XDP load-balancer benchmark, a simplified L4 load-balancer inspired by katran. The pipeline: L3/L4 parse -> VIP lookup -> per-CPU LRU connection table or consistent-hash fallback -> real server lookup -> per-VIP and per-real stats -> IPIP/IP6IP6 encapsulation. TCP SYN forces the consistent-hash path (skipping LRU); TCP RST skips LRU insert to avoid polluting the table. process_packet() is marked __noinline so that the BENCH_BPF_LOOP reset block (which strips encapsulation) operates on valid packet pointers after bpf_xdp_adjust_head(). Signed-off-by: Puranjay Mohan <puranjay@kernel.org> Link: https://lore.kernel.org/r/20260427232313.1582588-6-puranjay@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Puranjay Mohan
Alexei Starovoitov
parent
6b4003a7b3
commit
4b4f222910
647
tools/testing/selftests/bpf/progs/xdp_lb_bench.c
Normal file
647
tools/testing/selftests/bpf/progs/xdp_lb_bench.c
Normal file
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@ -0,0 +1,647 @@
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
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#include <stddef.h>
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#include <stdbool.h>
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#include <linux/bpf.h>
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#include <linux/if_ether.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <linux/in.h>
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#include <linux/tcp.h>
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#include <linux/udp.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_endian.h>
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#include "bpf_compiler.h"
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#include "xdp_lb_bench_common.h"
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#include "bench_bpf_timing.bpf.h"
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#ifndef IPPROTO_FRAGMENT
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#define IPPROTO_FRAGMENT 44
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#endif
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/* jhash helpers */
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static inline __u32 rol32(__u32 word, unsigned int shift)
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{
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return (word << shift) | (word >> ((-shift) & 31));
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}
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#define __jhash_mix(a, b, c) \
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{ \
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a -= c; a ^= rol32(c, 4); c += b; \
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b -= a; b ^= rol32(a, 6); a += c; \
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c -= b; c ^= rol32(b, 8); b += a; \
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a -= c; a ^= rol32(c, 16); c += b; \
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b -= a; b ^= rol32(a, 19); a += c; \
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c -= b; c ^= rol32(b, 4); b += a; \
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}
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#define __jhash_final(a, b, c) \
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{ \
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c ^= b; c -= rol32(b, 14); \
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a ^= c; a -= rol32(c, 11); \
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b ^= a; b -= rol32(a, 25); \
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c ^= b; c -= rol32(b, 16); \
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a ^= c; a -= rol32(c, 4); \
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b ^= a; b -= rol32(a, 14); \
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c ^= b; c -= rol32(b, 24); \
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}
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#define JHASH_INITVAL 0xdeadbeef
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static inline __u32 __jhash_nwords(__u32 a, __u32 b, __u32 c, __u32 initval)
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{
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a += initval;
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b += initval;
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c += initval;
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__jhash_final(a, b, c);
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return c;
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}
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static inline __u32 jhash_2words(__u32 a, __u32 b, __u32 initval)
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{
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return __jhash_nwords(a, b, 0, initval + JHASH_INITVAL + (2 << 2));
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}
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static inline __u32 jhash2_4words(const __u32 *k, __u32 initval)
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{
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__u32 a, b, c;
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a = b = c = JHASH_INITVAL + (4 << 2) + initval;
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a += k[0]; b += k[1]; c += k[2];
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__jhash_mix(a, b, c);
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a += k[3];
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__jhash_final(a, b, c);
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return c;
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}
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static __always_inline void ipv4_csum(struct iphdr *iph)
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{
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__u16 *next_iph = (__u16 *)iph;
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__u32 csum = 0;
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int i;
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__pragma_loop_unroll_full
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for (i = 0; i < (int)(sizeof(*iph) >> 1); i++)
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csum += *next_iph++;
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csum = (csum & 0xffff) + (csum >> 16);
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csum = (csum & 0xffff) + (csum >> 16);
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iph->check = ~csum;
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}
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(max_entries, 64);
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__type(key, struct vip_definition);
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__type(value, struct vip_meta);
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} vip_map SEC(".maps");
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struct lru_inner_map {
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__uint(type, BPF_MAP_TYPE_LRU_HASH);
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__type(key, struct flow_key);
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__type(value, struct real_pos_lru);
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__uint(max_entries, DEFAULT_LRU_SIZE);
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} lru_inner SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
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__type(key, __u32);
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__type(value, __u32);
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__uint(max_entries, BENCH_NR_CPUS);
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__array(values, struct lru_inner_map);
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} lru_mapping SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__uint(max_entries, CH_RINGS_SIZE);
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__type(key, __u32);
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__type(value, __u32);
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} ch_rings SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__uint(max_entries, MAX_REALS);
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__type(key, __u32);
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__type(value, struct real_definition);
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} reals SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
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__uint(max_entries, STATS_SIZE);
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__type(key, __u32);
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__type(value, struct lb_stats);
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} stats SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
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__uint(max_entries, MAX_REALS);
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__type(key, __u32);
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__type(value, struct lb_stats);
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} reals_stats SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__uint(max_entries, 1);
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__type(key, __u32);
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__type(value, struct ctl_value);
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} ctl_array SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__uint(max_entries, 1);
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__type(key, __u32);
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__type(value, struct vip_definition);
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} vip_miss_stats SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
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__uint(max_entries, MAX_REALS);
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__type(key, __u32);
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__type(value, __u32);
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} lru_miss_stats SEC(".maps");
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volatile __u32 flow_mask;
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volatile __u32 cold_lru;
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__u32 batch_gen;
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/*
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* old_eth MUST be read BEFORE writing the outer header because
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* bpf_xdp_adjust_head makes them overlap.
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*/
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static __always_inline int encap_v4(struct xdp_md *xdp, __be32 saddr, __be32 daddr,
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__u16 payload_len, const __u8 *dst_mac)
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{
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struct ethhdr *new_eth, *old_eth;
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void *data, *data_end;
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struct iphdr *iph;
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if (bpf_xdp_adjust_head(xdp, -(int)sizeof(struct iphdr)))
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return -1;
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data = (void *)(long)xdp->data;
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data_end = (void *)(long)xdp->data_end;
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new_eth = data;
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iph = data + sizeof(struct ethhdr);
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old_eth = data + sizeof(struct iphdr);
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if (new_eth + 1 > data_end || old_eth + 1 > data_end || iph + 1 > data_end)
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return -1;
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__builtin_memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source));
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__builtin_memcpy(new_eth->h_dest, dst_mac, sizeof(new_eth->h_dest));
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new_eth->h_proto = bpf_htons(ETH_P_IP);
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__builtin_memset(iph, 0, sizeof(*iph));
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iph->version = 4;
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iph->ihl = sizeof(*iph) >> 2;
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iph->protocol = IPPROTO_IPIP;
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iph->tot_len = bpf_htons(payload_len + sizeof(*iph));
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iph->ttl = 64;
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iph->saddr = saddr;
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iph->daddr = daddr;
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ipv4_csum(iph);
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return 0;
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}
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static __always_inline int encap_v6(struct xdp_md *xdp, const __be32 saddr[4],
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const __be32 daddr[4], __u8 nexthdr, __u16 payload_len,
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const __u8 *dst_mac)
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{
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struct ethhdr *new_eth, *old_eth;
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void *data, *data_end;
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struct ipv6hdr *ip6h;
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if (bpf_xdp_adjust_head(xdp, -(int)sizeof(struct ipv6hdr)))
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return -1;
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data = (void *)(long)xdp->data;
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data_end = (void *)(long)xdp->data_end;
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new_eth = data;
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ip6h = data + sizeof(struct ethhdr);
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old_eth = data + sizeof(struct ipv6hdr);
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if (new_eth + 1 > data_end || old_eth + 1 > data_end || ip6h + 1 > data_end)
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return -1;
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__builtin_memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source));
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__builtin_memcpy(new_eth->h_dest, dst_mac, sizeof(new_eth->h_dest));
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new_eth->h_proto = bpf_htons(ETH_P_IPV6);
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__builtin_memset(ip6h, 0, sizeof(*ip6h));
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ip6h->version = 6;
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ip6h->nexthdr = nexthdr;
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ip6h->payload_len = bpf_htons(payload_len);
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ip6h->hop_limit = 64;
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__builtin_memcpy(&ip6h->saddr, saddr, sizeof(ip6h->saddr));
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__builtin_memcpy(&ip6h->daddr, daddr, sizeof(ip6h->daddr));
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return 0;
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}
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static __always_inline void update_stats(void *map, __u32 key, __u16 bytes)
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{
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struct lb_stats *st = bpf_map_lookup_elem(map, &key);
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if (st) {
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st->v1 += 1;
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st->v2 += bytes;
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}
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}
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static __always_inline void count_action(int action)
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{
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struct lb_stats *st;
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__u32 key;
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if (action == XDP_TX)
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key = STATS_XDP_TX;
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else if (action == XDP_PASS)
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key = STATS_XDP_PASS;
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else
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key = STATS_XDP_DROP;
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st = bpf_map_lookup_elem(&stats, &key);
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if (st)
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st->v1 += 1;
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}
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static __always_inline bool is_under_flood(void)
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{
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__u32 key = STATS_NEW_CONN;
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struct lb_stats *conn_st = bpf_map_lookup_elem(&stats, &key);
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__u64 cur_time;
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if (!conn_st)
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return true;
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cur_time = bpf_ktime_get_ns();
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if ((cur_time - conn_st->v2) > ONE_SEC) {
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conn_st->v1 = 1;
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conn_st->v2 = cur_time;
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} else {
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conn_st->v1 += 1;
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if (conn_st->v1 > MAX_CONN_RATE)
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return true;
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}
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return false;
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}
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static __always_inline struct real_definition *connection_table_lookup(void *lru_map,
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struct flow_key *flow,
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__u32 *out_pos)
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{
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struct real_pos_lru *dst_lru;
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struct real_definition *real;
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__u32 key;
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dst_lru = bpf_map_lookup_elem(lru_map, flow);
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if (!dst_lru)
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return NULL;
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/* UDP connections use atime-based timeout instead of FIN/RST */
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if (flow->proto == IPPROTO_UDP) {
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__u64 cur_time = bpf_ktime_get_ns();
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if (cur_time - dst_lru->atime > LRU_UDP_TIMEOUT)
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return NULL;
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dst_lru->atime = cur_time;
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}
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key = dst_lru->pos;
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*out_pos = key;
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real = bpf_map_lookup_elem(&reals, &key);
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return real;
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}
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static __always_inline bool get_packet_dst(struct real_definition **real, struct flow_key *flow,
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struct vip_meta *vip_info, bool is_v6, void *lru_map,
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bool is_rst, __u32 *out_pos)
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{
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bool under_flood;
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__u32 hash, ch_key;
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__u32 *ch_val;
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__u32 real_pos;
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under_flood = is_under_flood();
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if (is_v6) {
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__u32 src_hash = jhash2_4words((__u32 *)flow->srcv6, MAX_VIPS);
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hash = jhash_2words(src_hash, flow->ports, CH_RING_SIZE);
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} else {
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hash = jhash_2words(flow->src, flow->ports, CH_RING_SIZE);
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}
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ch_key = CH_RING_SIZE * vip_info->vip_num + hash % CH_RING_SIZE;
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ch_val = bpf_map_lookup_elem(&ch_rings, &ch_key);
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if (!ch_val)
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return false;
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real_pos = *ch_val;
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*real = bpf_map_lookup_elem(&reals, &real_pos);
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if (!(*real))
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return false;
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if (!(vip_info->flags & F_LRU_BYPASS) && !under_flood && !is_rst) {
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struct real_pos_lru new_lru = { .pos = real_pos };
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if (flow->proto == IPPROTO_UDP)
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new_lru.atime = bpf_ktime_get_ns();
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bpf_map_update_elem(lru_map, flow, &new_lru, BPF_ANY);
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}
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*out_pos = real_pos;
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return true;
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}
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static __always_inline void update_vip_lru_miss_stats(struct vip_definition *vip, bool is_v6,
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__u32 real_idx)
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{
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struct vip_definition *miss_vip;
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__u32 key = 0;
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__u32 *cnt;
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miss_vip = bpf_map_lookup_elem(&vip_miss_stats, &key);
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if (!miss_vip)
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return;
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if (is_v6) {
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if (miss_vip->vipv6[0] != vip->vipv6[0] || miss_vip->vipv6[1] != vip->vipv6[1] ||
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miss_vip->vipv6[2] != vip->vipv6[2] || miss_vip->vipv6[3] != vip->vipv6[3])
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return;
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} else {
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if (miss_vip->vip != vip->vip)
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return;
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}
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if (miss_vip->port != vip->port || miss_vip->proto != vip->proto)
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return;
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cnt = bpf_map_lookup_elem(&lru_miss_stats, &real_idx);
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if (cnt)
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*cnt += 1;
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}
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static __noinline int process_packet(struct xdp_md *xdp)
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{
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void *data = (void *)(long)xdp->data;
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void *data_end = (void *)(long)xdp->data_end;
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struct ethhdr *eth = data;
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struct real_definition *dst = NULL;
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struct vip_definition vip_def = {};
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struct ctl_value *cval;
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struct flow_key flow = {};
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struct vip_meta *vip_info;
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struct lb_stats *data_stats;
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struct udphdr *uh;
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__be32 tnl_src[4];
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void *lru_map;
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void *l4;
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__u16 payload_len;
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__u32 real_pos = 0, cpu_num, key;
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__u8 proto;
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int action = XDP_DROP;
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bool is_v6, is_syn = false, is_rst = false;
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if (eth + 1 > data_end)
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goto out;
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if (eth->h_proto == bpf_htons(ETH_P_IPV6)) {
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is_v6 = true;
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} else if (eth->h_proto == bpf_htons(ETH_P_IP)) {
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is_v6 = false;
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} else {
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action = XDP_PASS;
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goto out;
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}
|
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|
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if (is_v6) {
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struct ipv6hdr *ip6h = (void *)(eth + 1);
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if (ip6h + 1 > data_end)
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goto out;
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if (ip6h->nexthdr == IPPROTO_FRAGMENT)
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goto out;
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payload_len = sizeof(struct ipv6hdr) + bpf_ntohs(ip6h->payload_len);
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proto = ip6h->nexthdr;
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||||
__builtin_memcpy(flow.srcv6, &ip6h->saddr, sizeof(flow.srcv6));
|
||||
__builtin_memcpy(flow.dstv6, &ip6h->daddr, sizeof(flow.dstv6));
|
||||
__builtin_memcpy(vip_def.vipv6, &ip6h->daddr, sizeof(vip_def.vipv6));
|
||||
l4 = (void *)(ip6h + 1);
|
||||
} else {
|
||||
struct iphdr *iph = (void *)(eth + 1);
|
||||
|
||||
if (iph + 1 > data_end)
|
||||
goto out;
|
||||
if (iph->ihl != 5)
|
||||
goto out;
|
||||
if (iph->frag_off & bpf_htons(PCKT_FRAGMENTED))
|
||||
goto out;
|
||||
|
||||
payload_len = bpf_ntohs(iph->tot_len);
|
||||
proto = iph->protocol;
|
||||
|
||||
flow.src = iph->saddr;
|
||||
flow.dst = iph->daddr;
|
||||
vip_def.vip = iph->daddr;
|
||||
l4 = (void *)(iph + 1);
|
||||
}
|
||||
|
||||
/* TCP and UDP share the same port layout at offset 0 */
|
||||
if (proto != IPPROTO_TCP && proto != IPPROTO_UDP) {
|
||||
action = XDP_PASS;
|
||||
goto out;
|
||||
}
|
||||
|
||||
uh = l4;
|
||||
if ((void *)(uh + 1) > data_end)
|
||||
goto out;
|
||||
flow.port16[0] = uh->source;
|
||||
flow.port16[1] = uh->dest;
|
||||
|
||||
if (proto == IPPROTO_TCP) {
|
||||
struct tcphdr *th = l4;
|
||||
|
||||
if ((void *)(th + 1) > data_end)
|
||||
goto out;
|
||||
is_syn = th->syn;
|
||||
is_rst = th->rst;
|
||||
}
|
||||
|
||||
flow.proto = proto;
|
||||
vip_def.port = flow.port16[1];
|
||||
vip_def.proto = proto;
|
||||
|
||||
vip_info = bpf_map_lookup_elem(&vip_map, &vip_def);
|
||||
if (!vip_info) {
|
||||
action = XDP_PASS;
|
||||
goto out;
|
||||
}
|
||||
|
||||
key = STATS_LRU;
|
||||
data_stats = bpf_map_lookup_elem(&stats, &key);
|
||||
if (!data_stats)
|
||||
goto out;
|
||||
data_stats->v1 += 1;
|
||||
|
||||
cpu_num = bpf_get_smp_processor_id();
|
||||
lru_map = bpf_map_lookup_elem(&lru_mapping, &cpu_num);
|
||||
if (!lru_map)
|
||||
goto out;
|
||||
|
||||
if (!(vip_info->flags & F_LRU_BYPASS) && !is_syn)
|
||||
dst = connection_table_lookup(lru_map, &flow, &real_pos);
|
||||
|
||||
if (!dst) {
|
||||
if (flow.proto == IPPROTO_TCP) {
|
||||
struct lb_stats *miss_st;
|
||||
|
||||
key = STATS_LRU_MISS;
|
||||
miss_st = bpf_map_lookup_elem(&stats, &key);
|
||||
if (miss_st)
|
||||
miss_st->v1 += 1;
|
||||
}
|
||||
|
||||
if (!get_packet_dst(&dst, &flow, vip_info, is_v6, lru_map, is_rst, &real_pos))
|
||||
goto out;
|
||||
|
||||
update_vip_lru_miss_stats(&vip_def, is_v6, real_pos);
|
||||
data_stats->v2 += 1;
|
||||
}
|
||||
|
||||
key = 0;
|
||||
cval = bpf_map_lookup_elem(&ctl_array, &key);
|
||||
if (!cval)
|
||||
goto out;
|
||||
|
||||
update_stats(&stats, vip_info->vip_num, payload_len);
|
||||
update_stats(&reals_stats, real_pos, payload_len);
|
||||
|
||||
if (is_v6) {
|
||||
create_encap_ipv6_src(flow.port16[0], flow.srcv6[0], tnl_src);
|
||||
if (encap_v6(xdp, tnl_src, dst->dstv6, IPPROTO_IPV6, payload_len, cval->mac))
|
||||
goto out;
|
||||
} else if (dst->flags & F_IPV6) {
|
||||
create_encap_ipv6_src(flow.port16[0], flow.src, tnl_src);
|
||||
if (encap_v6(xdp, tnl_src, dst->dstv6, IPPROTO_IPIP, payload_len, cval->mac))
|
||||
goto out;
|
||||
} else {
|
||||
if (encap_v4(xdp, create_encap_ipv4_src(flow.port16[0], flow.src), dst->dst,
|
||||
payload_len, cval->mac))
|
||||
goto out;
|
||||
}
|
||||
|
||||
action = XDP_TX;
|
||||
|
||||
out:
|
||||
count_action(action);
|
||||
return action;
|
||||
}
|
||||
|
||||
static __always_inline int strip_encap(struct xdp_md *xdp, const struct ethhdr *saved_eth)
|
||||
{
|
||||
void *data = (void *)(long)xdp->data;
|
||||
void *data_end = (void *)(long)xdp->data_end;
|
||||
struct ethhdr *eth = data;
|
||||
int hdr_sz;
|
||||
|
||||
if (eth + 1 > data_end)
|
||||
return -1;
|
||||
|
||||
hdr_sz = (eth->h_proto == bpf_htons(ETH_P_IPV6)) ? (int)sizeof(struct ipv6hdr)
|
||||
: (int)sizeof(struct iphdr);
|
||||
|
||||
if (bpf_xdp_adjust_head(xdp, hdr_sz))
|
||||
return -1;
|
||||
|
||||
data = (void *)(long)xdp->data;
|
||||
data_end = (void *)(long)xdp->data_end;
|
||||
eth = data;
|
||||
|
||||
if (eth + 1 > data_end)
|
||||
return -1;
|
||||
|
||||
__builtin_memcpy(eth, saved_eth, sizeof(*saved_eth));
|
||||
return 0;
|
||||
}
|
||||
|
||||
static __always_inline void randomize_src(struct xdp_md *xdp, int saddr_off, __u32 *rand_state)
|
||||
{
|
||||
void *data = (void *)(long)xdp->data;
|
||||
void *data_end = (void *)(long)xdp->data_end;
|
||||
__u32 *saddr = data + saddr_off;
|
||||
|
||||
*rand_state ^= *rand_state << 13;
|
||||
*rand_state ^= *rand_state >> 17;
|
||||
*rand_state ^= *rand_state << 5;
|
||||
|
||||
if ((void *)(saddr + 1) <= data_end)
|
||||
*saddr = *rand_state & flow_mask;
|
||||
}
|
||||
|
||||
SEC("xdp")
|
||||
int xdp_lb_bench(struct xdp_md *xdp)
|
||||
{
|
||||
void *data = (void *)(long)xdp->data;
|
||||
void *data_end = (void *)(long)xdp->data_end;
|
||||
struct ethhdr *eth = data;
|
||||
struct ethhdr saved_eth;
|
||||
__u32 rand_state = 0;
|
||||
__u32 batch_hash = 0;
|
||||
int saddr_off = 0;
|
||||
bool is_v6;
|
||||
|
||||
if (eth + 1 > data_end)
|
||||
return XDP_DROP;
|
||||
|
||||
__builtin_memcpy(&saved_eth, eth, sizeof(saved_eth));
|
||||
|
||||
is_v6 = (saved_eth.h_proto == bpf_htons(ETH_P_IPV6));
|
||||
|
||||
saddr_off = sizeof(struct ethhdr) + (is_v6 ? offsetof(struct ipv6hdr, saddr) :
|
||||
offsetof(struct iphdr, saddr));
|
||||
|
||||
if (flow_mask)
|
||||
rand_state = bpf_get_prandom_u32() | 1;
|
||||
|
||||
if (cold_lru) {
|
||||
__u32 *saddr = data + saddr_off;
|
||||
|
||||
batch_gen++;
|
||||
batch_hash = (batch_gen ^ bpf_get_smp_processor_id()) * KNUTH_HASH_MULT;
|
||||
if ((void *)(saddr + 1) <= data_end)
|
||||
*saddr ^= batch_hash;
|
||||
}
|
||||
|
||||
return BENCH_BPF_LOOP(
|
||||
process_packet(xdp),
|
||||
({
|
||||
if (__bench_result == XDP_TX) {
|
||||
if (strip_encap(xdp, &saved_eth))
|
||||
return XDP_DROP;
|
||||
if (rand_state)
|
||||
randomize_src(xdp, saddr_off, &rand_state);
|
||||
}
|
||||
if (cold_lru) {
|
||||
void *d = (void *)(long)xdp->data;
|
||||
void *de = (void *)(long)xdp->data_end;
|
||||
__u32 *__sa = d + saddr_off;
|
||||
|
||||
if ((void *)(__sa + 1) <= de)
|
||||
*__sa ^= batch_hash;
|
||||
}
|
||||
})
|
||||
);
|
||||
}
|
||||
|
||||
char _license[] SEC("license") = "GPL";
|
||||
Loading…
Reference in New Issue
Block a user