Add AF_XDP samples

kernel/samples/bpf/Makefile

@@ -12,6 +12,7 @@ TARGETS += bpf_tail_calls01
 TARGETS += napi_monitor
 TARGETS += xdp_monitor
 TARGETS += xdp_redirect_err
+TARGETS += xdpsock
 
 # Linking with libbpf and libpcap
 TARGETS_PCAP += xdp_tcpdump
@@ -76,7 +77,7 @@ CFLAGS += -I./kernel-usr-include/
 # Interacting with libbpf
 CFLAGS += -I$(TOOLS_PATH)/lib
 
-LDFLAGS= -lelf
+LDFLAGS= -lelf -lpthread
 
 # Objects that xxx_user program is linked with:
 OBJECT_LOADBPF = bpf_load.o

kernel/samples/bpf/xdpsock.h

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef XDPSOCK_H_
+#define XDPSOCK_H_
+
+/* Power-of-2 number of sockets */
+#define MAX_SOCKS 4
+
+/* Round-robin receive */
+#define RR_LB 0
+
+#endif /* XDPSOCK_H_ */

kernel/samples/bpf/xdpsock_kern.c

@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0
+#define KBUILD_MODNAME "foo"
+#include <uapi/linux/bpf.h>
+#include "bpf_helpers.h"
+
+#include "xdpsock.h"
+
+struct bpf_map_def SEC("maps") qidconf_map = {
+	.type		= BPF_MAP_TYPE_ARRAY,
+	.key_size	= sizeof(int),
+	.value_size	= sizeof(int),
+	.max_entries	= 1,
+};
+
+struct bpf_map_def SEC("maps") xsks_map = {
+	.type = BPF_MAP_TYPE_XSKMAP,
+	.key_size = sizeof(int),
+	.value_size = sizeof(int),
+	.max_entries = MAX_SOCKS,
+};
+
+struct bpf_map_def SEC("maps") rr_map = {
+	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
+	.key_size = sizeof(int),
+	.value_size = sizeof(unsigned int),
+	.max_entries = 1,
+};
+
+SEC("xdp_sock")
+int xdp_sock_prog(struct xdp_md *ctx)
+{
+	int *qidconf, key = 0, idx;
+	//unsigned int *rr;
+
+	qidconf = bpf_map_lookup_elem(&qidconf_map, &key);
+	if (!qidconf)
+		return XDP_ABORTED;
+
+	if (*qidconf != ctx->rx_queue_index)
+		return XDP_PASS;
+
+#if RR_LB /* NB! RR_LB is configured in xdpsock.h */
+	rr = bpf_map_lookup_elem(&rr_map, &key);
+	if (!rr)
+		return XDP_ABORTED;
+
+	*rr = (*rr + 1) & (MAX_SOCKS - 1);
+	idx = *rr;
+#else
+	idx = 0;
+#endif
+
+	return bpf_redirect_map(&xsks_map, idx, 0);
+}
+
+char _license[] SEC("license") = "GPL";