1 files changed, 96 insertions, 0 deletions
diff --git a/samples/bpf/xdp_rxq_info_kern.c b/samples/bpf/xdp_rxq_info_kern.c
new file mode 100644
index 000000000000..3fd209291653
--- /dev/null
+++ b/samples/bpf/xdp_rxq_info_kern.c
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0
+ * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
+ *
+ *  Example howto extract XDP RX-queue info
+ */
+#include <uapi/linux/bpf.h>
+#include "bpf_helpers.h"
+
+/* Config setup from with userspace
+ *
+ * User-side setup ifindex in config_map, to verify that
+ * ctx->ingress_ifindex is correct (against configured ifindex)
+ */
+struct config {
+	__u32 action;
+	int ifindex;
+};
+struct bpf_map_def SEC("maps") config_map = {
+	.type		= BPF_MAP_TYPE_ARRAY,
+	.key_size	= sizeof(int),
+	.value_size	= sizeof(struct config),
+	.max_entries	= 1,
+};
+
+/* Common stats data record (shared with userspace) */
+struct datarec {
+	__u64 processed;
+	__u64 issue;
+};
+
+struct bpf_map_def SEC("maps") stats_global_map = {
+	.type		= BPF_MAP_TYPE_PERCPU_ARRAY,
+	.key_size	= sizeof(u32),
+	.value_size	= sizeof(struct datarec),
+	.max_entries	= 1,
+};
+
+#define MAX_RXQs 64
+
+/* Stats per rx_queue_index (per CPU) */
+struct bpf_map_def SEC("maps") rx_queue_index_map = {
+	.type		= BPF_MAP_TYPE_PERCPU_ARRAY,
+	.key_size	= sizeof(u32),
+	.value_size	= sizeof(struct datarec),
+	.max_entries	= MAX_RXQs + 1,
+};
+
+SEC("xdp_prog0")
+int  xdp_prognum0(struct xdp_md *ctx)
+{
+	void *data_end = (void *)(long)ctx->data_end;
+	void *data     = (void *)(long)ctx->data;
+	struct datarec *rec, *rxq_rec;
+	int ingress_ifindex;
+	struct config *config;
+	u32 key = 0;
+
+	/* Global stats record */
+	rec = bpf_map_lookup_elem(&stats_global_map, &key);
+	if (!rec)
+		return XDP_ABORTED;
+	rec->processed++;
+
+	/* Accessing ctx->ingress_ifindex, cause BPF to rewrite BPF
+	 * instructions inside kernel to access xdp_rxq->dev->ifindex
+	 */
+	ingress_ifindex = ctx->ingress_ifindex;
+
+	config = bpf_map_lookup_elem(&config_map, &key);
+	if (!config)
+		return XDP_ABORTED;
+
+	/* Simple test: check ctx provided ifindex is as expected */
+	if (ingress_ifindex != config->ifindex) {
+		/* count this error case */
+		rec->issue++;
+		return XDP_ABORTED;
+	}
+
+	/* Update stats per rx_queue_index. Handle if rx_queue_index
+	 * is larger than stats map can contain info for.
+	 */
+	key = ctx->rx_queue_index;
+	if (key >= MAX_RXQs)
+		key = MAX_RXQs;
+	rxq_rec = bpf_map_lookup_elem(&rx_queue_index_map, &key);
+	if (!rxq_rec)
+		return XDP_ABORTED;
+	rxq_rec->processed++;
+	if (key == MAX_RXQs)
+		rxq_rec->issue++;
+
+	return config->action;
+}
+
+char _license[] SEC("license") = "GPL";