[2/2 bpf-next] bpf: add selftest to read xdp_md fields

[John Fastabend <john.fastabend@xxxxxxxxx>]

This adds a selftest to read the xdp_md net_device and extract common
fields we use. This will also compare xdp_md->ifindex with the value
extracted through the dev pointer.

Signed-off-by: John Fastabend <john.fastabend@xxxxxxxxx>
---
 .../testing/selftests/bpf/prog_tests/xdp_md.c | 35 +++++++++++++++++++
 .../testing/selftests/bpf/progs/test_xdp_md.c | 25 +++++++++++++
 2 files changed, 60 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_md.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_md.c

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_md.c b/tools/testing/selftests/bpf/prog_tests/xdp_md.c
new file mode 100644
index 000000000000..facf3f3ab86f
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_md.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include <network_helpers.h>
+#include "test_xdp_md.skel.h"
+
+void test_xdp_md(void)
+{
+	struct test_xdp_md *skel;
+	int err, prog_fd;
+	char buf[128];
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts,
+		.data_in = &pkt_v4,
+		.data_size_in = sizeof(pkt_v4),
+		.data_out = buf,
+		.data_size_out = sizeof(buf),
+		.repeat = 1,
+	);
+
+	skel = test_xdp_md__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.md_xdp);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+	ASSERT_EQ(topts.retval, XDP_PASS, "xdp_md test_run retval");
+
+	ASSERT_EQ(skel->bss->ifindex, 1, "xdp_md ifindex");
+	ASSERT_EQ(skel->bss->ifindex, skel->bss->ingress_ifindex, "xdp_md ingress_ifindex");
+	ASSERT_STREQ(skel->bss->name, "lo", "xdp_md name");
+	ASSERT_NEQ(skel->bss->inum, 0, "xdp_md inum");
+
+	test_xdp_md__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_xdp_md.c b/tools/testing/selftests/bpf/progs/test_xdp_md.c
new file mode 100644
index 000000000000..66ad4a7c80cd
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_xdp_md.c
@@ -0,0 +1,25 @@
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <string.h>
+
+#define	IFNAMSIZ 16
+
+int ifindex, ingress_ifindex;
+char name[IFNAMSIZ];
+unsigned int inum;
+
+SEC("xdp")
+int md_xdp(struct xdp_md *ctx)
+{
+	struct net_device *dev;
+
+	dev = ctx->rx_dev;
+
+	ifindex = dev->ifindex;
+	inum = dev->nd_net.net->ns.inum;
+	memcpy(name, dev->name, IFNAMSIZ);
+	ingress_ifindex = ctx->ingress_ifindex;
+	return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.33.0