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