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 "bpf_helpers.h"
 8
 9/* Config setup from with userspace
10 *
11 * User-side setup ifindex in config_map, to verify that
12 * ctx->ingress_ifindex is correct (against configured ifindex)
13 */
14struct config {
15	__u32 action;
16	int ifindex;
17};
18struct bpf_map_def SEC("maps") config_map = {
19	.type		= BPF_MAP_TYPE_ARRAY,
20	.key_size	= sizeof(int),
21	.value_size	= sizeof(struct config),
22	.max_entries	= 1,
23};
24
25/* Common stats data record (shared with userspace) */
26struct datarec {
27	__u64 processed;
28	__u64 issue;
29};
30
31struct bpf_map_def SEC("maps") stats_global_map = {
32	.type		= BPF_MAP_TYPE_PERCPU_ARRAY,
33	.key_size	= sizeof(u32),
34	.value_size	= sizeof(struct datarec),
35	.max_entries	= 1,
36};
37
38#define MAX_RXQs 64
39
40/* Stats per rx_queue_index (per CPU) */
41struct bpf_map_def SEC("maps") rx_queue_index_map = {
42	.type		= BPF_MAP_TYPE_PERCPU_ARRAY,
43	.key_size	= sizeof(u32),
44	.value_size	= sizeof(struct datarec),
45	.max_entries	= MAX_RXQs + 1,
46};
47
48SEC("xdp_prog0")
49int  xdp_prognum0(struct xdp_md *ctx)
50{
51	void *data_end = (void *)(long)ctx->data_end;
52	void *data     = (void *)(long)ctx->data;
53	struct datarec *rec, *rxq_rec;
54	int ingress_ifindex;
55	struct config *config;
56	u32 key = 0;
57
58	/* Global stats record */
59	rec = bpf_map_lookup_elem(&stats_global_map, &key);
60	if (!rec)
61		return XDP_ABORTED;
62	rec->processed++;
63
64	/* Accessing ctx->ingress_ifindex, cause BPF to rewrite BPF
65	 * instructions inside kernel to access xdp_rxq->dev->ifindex
66	 */
67	ingress_ifindex = ctx->ingress_ifindex;
68
69	config = bpf_map_lookup_elem(&config_map, &key);
70	if (!config)
71		return XDP_ABORTED;
72
73	/* Simple test: check ctx provided ifindex is as expected */
74	if (ingress_ifindex != config->ifindex) {
75		/* count this error case */
76		rec->issue++;
77		return XDP_ABORTED;
78	}
79
80	/* Update stats per rx_queue_index. Handle if rx_queue_index
81	 * is larger than stats map can contain info for.
82	 */
83	key = ctx->rx_queue_index;
84	if (key >= MAX_RXQs)
85		key = MAX_RXQs;
86	rxq_rec = bpf_map_lookup_elem(&rx_queue_index_map, &key);
87	if (!rxq_rec)
88		return XDP_ABORTED;
89	rxq_rec->processed++;
90	if (key == MAX_RXQs)
91		rxq_rec->issue++;
92
93	return config->action;
94}
95
96char _license[] SEC("license") = "GPL";