[PATCH RFC bpf-next 3/3] selftests/bpf: Add selftest for XDP multiprogs

["Toke Høiland-Jørgensen" <toke@redhat.com>]

From: Toke Høiland-Jørgensen <toke@redhat.com>

This adds a simple selftest that combines two XDP programs through a third
dispatcher, exercising the libbpf function externals handling.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 .../selftests/bpf/prog_tests/xdp_multiprog.c       |   52 ++++++++++++++++++++
 tools/testing/selftests/bpf/progs/xdp_drop.c       |   13 +++++
 tools/testing/selftests/bpf/progs/xdp_multiprog.c  |   26 ++++++++++
 3 files changed, 91 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_multiprog.c
 create mode 100644 tools/testing/selftests/bpf/progs/xdp_drop.c
 create mode 100644 tools/testing/selftests/bpf/progs/xdp_multiprog.c

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_multiprog.c b/tools/testing/selftests/bpf/prog_tests/xdp_multiprog.c
new file mode 100644
index 000000000000..40a743437222
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_multiprog.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+
+void test_xdp_multiprog(void)
+{
+	const char *file_dispatcher = "./xdp_multiprog.o";
+	const char *file_drop = "./xdp_drop.o";
+	const char *file_pass = "./xdp_dummy.o";
+	struct bpf_object *obj, *obj_drop, *obj_pass;
+	int err;
+
+
+	obj = bpf_object__open_file(file_dispatcher, NULL);
+	err = libbpf_get_error(obj);
+	if (CHECK_FAIL(err))
+		return;
+
+	obj_drop = bpf_object__open_file(file_drop, NULL);
+	err = libbpf_get_error(obj_drop);
+	if (CHECK_FAIL(err))
+		goto out_obj;
+
+	obj_pass = bpf_object__open_file(file_pass, NULL);
+	err = libbpf_get_error(obj_pass);
+	if (CHECK_FAIL(err))
+		goto out_drop;
+
+        err = bpf_object__load(obj_drop);
+        err = err ?: bpf_object__load(obj_pass);
+
+        if (CHECK_FAIL(err))
+                goto out;
+
+	struct bpf_extern_call_tgt tgts[] =
+		{
+		 {.name = "prog1", .tgt_prog_name = "xdp_dummy_prog", .tgt_obj = obj_pass},
+		 {.name = "prog2", .tgt_prog_name = "xdp_drop_prog", .tgt_obj = obj_drop},
+		};
+	struct bpf_extern_calls calls = {.num_tgts = 2, .tgts = tgts };
+
+	DECLARE_LIBBPF_OPTS(bpf_object_load_opts, load_opts,
+			    .ext_calls = &calls);
+
+	err = bpf_object__load2(obj, &load_opts);
+        CHECK_FAIL(err);
+out:
+	bpf_object__close(obj_pass);
+out_drop:
+	bpf_object__close(obj_drop);
+out_obj:
+	bpf_object__close(obj);
+}
diff --git a/tools/testing/selftests/bpf/progs/xdp_drop.c b/tools/testing/selftests/bpf/progs/xdp_drop.c
new file mode 100644
index 000000000000..10e415e49564
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/xdp_drop.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define KBUILD_MODNAME "xdp_drop"
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+SEC("xdp_drop")
+int xdp_drop_prog(struct xdp_md *ctx)
+{
+	return XDP_DROP;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/xdp_multiprog.c b/tools/testing/selftests/bpf/progs/xdp_multiprog.c
new file mode 100644
index 000000000000..ef5ba8172038
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/xdp_multiprog.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define KBUILD_MODNAME "xdp_multiprog"
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+extern int prog1(struct xdp_md *ctx);
+extern int prog2(struct xdp_md *ctx);
+
+SEC("xdp_test")
+int xdp_main(struct xdp_md *ctx)
+{
+        int ret;
+
+        ret = prog1(ctx);
+        if (ret != XDP_PASS)
+                goto out;
+
+        ret = prog2(ctx);
+        if (ret != XDP_DROP)
+                goto out;
+out:
+        return ret;
+}
+
+char _license[] SEC("license") = "GPL";