xdp-project-bpf-examples/AF_XDP-interaction/af_xdp_kern.c

/* SPDX-License-Identifier: GPL-2.0 */

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#if 1
struct bpf_map_def SEC("maps") xsks_map = {
	.type = BPF_MAP_TYPE_XSKMAP,
	.key_size = sizeof(int),
	.value_size = sizeof(int),
	.max_entries = 64,  /* Assume netdev has no more than 64 queues */
};
#else
struct {
	__uint(type, BPF_MAP_TYPE_XSKMAP);
        __uint(max_entries, 64); /* Assume netdev has no more than 64 queues */
        __uint(key_size, sizeof(int));
        __uint(value_size, sizeof(int));
} xsks_map SEC(".maps");
#endif

#if 1
struct bpf_map_def SEC("maps") xdp_stats_map = {
	.type        = BPF_MAP_TYPE_PERCPU_ARRAY,
	.key_size    = sizeof(int),
	.value_size  = sizeof(__u32),
	.max_entries = 64,
};
#else
struct {
	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
        __type(key, __u32);
        __type(value, __u32);
	__uint(max_entries, 64);
} xdp_stats_map SEC(".maps");
#endif

SEC("xdp_sock")
int xdp_sock_prog(struct xdp_md *ctx)
{
	int index = ctx->rx_queue_index;
	__u32 *pkt_count;

	pkt_count = bpf_map_lookup_elem(&xdp_stats_map, &index);
	if (pkt_count) {

		/* We pass every other packet */
		if ((*pkt_count)++ & 1)
			return XDP_PASS;
	}

	/* A set entry here means that the correspnding queue_id
	 * has an active AF_XDP socket bound to it. */
	if (bpf_map_lookup_elem(&xsks_map, &index))
		return bpf_redirect_map(&xsks_map, index, 0);

	return XDP_PASS;
}

char _license[] SEC("license") = "GPL";