1 /* SPDX-License-Identifier: GPL-2.0
2 * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
4 * Example howto extract XDP RX-queue info
6 #include <uapi/linux/bpf.h>
7 #include <uapi/linux/if_ether.h>
8 #include <uapi/linux/in.h>
9 #include <bpf/bpf_helpers.h>
11 /* Config setup from with userspace
13 * User-side setup ifindex in config_map, to verify that
14 * ctx->ingress_ifindex is correct (against configured ifindex)
21 enum cfg_options_flags {
28 __uint(type, BPF_MAP_TYPE_ARRAY);
30 __type(value, struct config);
31 __uint(max_entries, 1);
32 } config_map SEC(".maps");
34 /* Common stats data record (shared with userspace) */
41 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
43 __type(value, struct datarec);
44 __uint(max_entries, 1);
45 } stats_global_map SEC(".maps");
49 /* Stats per rx_queue_index (per CPU) */
51 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
53 __type(value, struct datarec);
54 __uint(max_entries, MAX_RXQs + 1);
55 } rx_queue_index_map SEC(".maps");
57 static __always_inline
58 void swap_src_dst_mac(void *data)
60 unsigned short *p = data;
61 unsigned short dst[3];
75 int xdp_prognum0(struct xdp_md *ctx)
77 void *data_end = (void *)(long)ctx->data_end;
78 void *data = (void *)(long)ctx->data;
79 struct datarec *rec, *rxq_rec;
81 struct config *config;
84 /* Global stats record */
85 rec = bpf_map_lookup_elem(&stats_global_map, &key);
90 /* Accessing ctx->ingress_ifindex, cause BPF to rewrite BPF
91 * instructions inside kernel to access xdp_rxq->dev->ifindex
93 ingress_ifindex = ctx->ingress_ifindex;
95 config = bpf_map_lookup_elem(&config_map, &key);
99 /* Simple test: check ctx provided ifindex is as expected */
100 if (ingress_ifindex != config->ifindex) {
101 /* count this error case */
106 /* Update stats per rx_queue_index. Handle if rx_queue_index
107 * is larger than stats map can contain info for.
109 key = ctx->rx_queue_index;
112 rxq_rec = bpf_map_lookup_elem(&rx_queue_index_map, &key);
115 rxq_rec->processed++;
119 /* Default: Don't touch packet data, only count packets */
120 if (unlikely(config->options & (READ_MEM|SWAP_MAC))) {
121 struct ethhdr *eth = data;
123 if (eth + 1 > data_end)
126 /* Avoid compiler removing this: Drop non 802.3 Ethertypes */
127 if (ntohs(eth->h_proto) < ETH_P_802_3_MIN)
130 /* XDP_TX requires changing MAC-addrs, else HW may drop.
131 * Can also be enabled with --swapmac (for test purposes)
133 if (unlikely(config->options & SWAP_MAC))
134 swap_src_dst_mac(data);
137 return config->action;
140 char _license[] SEC("license") = "GPL";