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 */
 16struct config {
 17	__u32 action;
 18	int ifindex;
 19	__u32 options;
 20};
 21enum cfg_options_flags {
 22	NO_TOUCH = 0x0U,
 23	READ_MEM = 0x1U,
 24	SWAP_MAC = 0x2U,
 25};
 26
 27struct {
 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) */
 35struct datarec {
 36	__u64 processed;
 37	__u64 issue;
 38};
 39
 40struct {
 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) */
 50struct {
 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
 57static __always_inline
 58void 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
 74SEC("xdp_prog0")
 75int  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
140char _license[] SEC("license") = "GPL";