1 /* SPDX-License-Identifier: GPL-2.0
2 * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
3 *
4 * Example howto extract XDP RX-queue info
5 */
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>
10
11 /* Config setup from with userspace
12 *
13 * User-side setup ifindex in config_map, to verify that
14 * ctx->ingress_ifindex is correct (against configured ifindex)
15 */
16 struct config {
17 __u32 action;
18 int ifindex;
19 __u32 options;
20 };
21 enum cfg_options_flags {
22 NO_TOUCH = 0x0U,
23 READ_MEM = 0x1U,
24 SWAP_MAC = 0x2U,
25 };
26
27 struct {
28 __uint(type, BPF_MAP_TYPE_ARRAY);
29 __type(key, int);
30 __type(value, struct config);
31 __uint(max_entries, 1);
32 } config_map SEC(".maps");
33
34 /* Common stats data record (shared with userspace) */
35 struct datarec {
36 __u64 processed;
37 __u64 issue;
38 };
39
40 struct {
41 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
42 __type(key, u32);
43 __type(value, struct datarec);
44 __uint(max_entries, 1);
45 } stats_global_map SEC(".maps");
46
47 #define MAX_RXQs 64
48
49 /* Stats per rx_queue_index (per CPU) */
50 struct {
51 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
52 __type(key, u32);
53 __type(value, struct datarec);
54 __uint(max_entries, MAX_RXQs + 1);
55 } rx_queue_index_map SEC(".maps");
56
57 static __always_inline
swap_src_dst_mac(void * data)58 void swap_src_dst_mac(void *data)
59 {
60 unsigned short *p = data;
61 unsigned short dst[3];
62
63 dst[0] = p[0];
64 dst[1] = p[1];
65 dst[2] = p[2];
66 p[0] = p[3];
67 p[1] = p[4];
68 p[2] = p[5];
69 p[3] = dst[0];
70 p[4] = dst[1];
71 p[5] = dst[2];
72 }
73
74 SEC("xdp_prog0")
xdp_prognum0(struct xdp_md * ctx)75 int xdp_prognum0(struct xdp_md *ctx)
76 {
77 void *data_end = (void *)(long)ctx->data_end;
78 void *data = (void *)(long)ctx->data;
79 struct datarec *rec, *rxq_rec;
80 int ingress_ifindex;
81 struct config *config;
82 u32 key = 0;
83
84 /* Global stats record */
85 rec = bpf_map_lookup_elem(&stats_global_map, &key);
86 if (!rec)
87 return XDP_ABORTED;
88 rec->processed++;
89
90 /* Accessing ctx->ingress_ifindex, cause BPF to rewrite BPF
91 * instructions inside kernel to access xdp_rxq->dev->ifindex
92 */
93 ingress_ifindex = ctx->ingress_ifindex;
94
95 config = bpf_map_lookup_elem(&config_map, &key);
96 if (!config)
97 return XDP_ABORTED;
98
99 /* Simple test: check ctx provided ifindex is as expected */
100 if (ingress_ifindex != config->ifindex) {
101 /* count this error case */
102 rec->issue++;
103 return XDP_ABORTED;
104 }
105
106 /* Update stats per rx_queue_index. Handle if rx_queue_index
107 * is larger than stats map can contain info for.
108 */
109 key = ctx->rx_queue_index;
110 if (key >= MAX_RXQs)
111 key = MAX_RXQs;
112 rxq_rec = bpf_map_lookup_elem(&rx_queue_index_map, &key);
113 if (!rxq_rec)
114 return XDP_ABORTED;
115 rxq_rec->processed++;
116 if (key == MAX_RXQs)
117 rxq_rec->issue++;
118
119 /* Default: Don't touch packet data, only count packets */
120 if (unlikely(config->options & (READ_MEM|SWAP_MAC))) {
121 struct ethhdr *eth = data;
122
123 if (eth + 1 > data_end)
124 return XDP_ABORTED;
125
126 /* Avoid compiler removing this: Drop non 802.3 Ethertypes */
127 if (ntohs(eth->h_proto) < ETH_P_802_3_MIN)
128 return XDP_ABORTED;
129
130 /* XDP_TX requires changing MAC-addrs, else HW may drop.
131 * Can also be enabled with --swapmac (for test purposes)
132 */
133 if (unlikely(config->options & SWAP_MAC))
134 swap_src_dst_mac(data);
135 }
136
137 return config->action;
138 }
139
140 char _license[] SEC("license") = "GPL";
141