selftests/bpf: Add test for kfunc module order

Add a test case for kfuncs from multiple external modules, checking
that the correct kfuncs are called regardless of which order they're
called in. Specifically, check that calling the kfuncs in an order
different from the one the modules' BTF are loaded in works.

Signed-off-by: Simon Sundberg <simon.sundberg@kau.se>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20241010-fix-kfunc-btf-caching-for-modules-v2-3-745af6c1af98@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 55 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/kfunc_module_order.c b/tools/testing/selftests/bpf/prog_tests/kfunc_module_order.c
new file mode 100644
index 000000000000..48c0560d398e
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/kfunc_module_order.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include <testing_helpers.h>
+
+#include "kfunc_module_order.skel.h"
+
+static int test_run_prog(const struct bpf_program *prog,
+			 struct bpf_test_run_opts *opts)
+{
+	int err;
+
+	err = bpf_prog_test_run_opts(bpf_program__fd(prog), opts);
+	if (!ASSERT_OK(err, "bpf_prog_test_run_opts"))
+		return err;
+
+	if (!ASSERT_EQ((int)opts->retval, 0, bpf_program__name(prog)))
+		return -EINVAL;
+
+	return 0;
+}
+
+void test_kfunc_module_order(void)
+{
+	struct kfunc_module_order *skel;
+	char pkt_data[64] = {};
+	int err = 0;
+
+	DECLARE_LIBBPF_OPTS(bpf_test_run_opts, test_opts, .data_in = pkt_data,
+			    .data_size_in = sizeof(pkt_data));
+
+	err = load_module("bpf_test_modorder_x.ko",
+			  env_verbosity > VERBOSE_NONE);
+	if (!ASSERT_OK(err, "load bpf_test_modorder_x.ko"))
+		return;
+
+	err = load_module("bpf_test_modorder_y.ko",
+			  env_verbosity > VERBOSE_NONE);
+	if (!ASSERT_OK(err, "load bpf_test_modorder_y.ko"))
+		goto exit_modx;
+
+	skel = kfunc_module_order__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "kfunc_module_order__open_and_load()")) {
+		err = -EINVAL;
+		goto exit_mods;
+	}
+
+	test_run_prog(skel->progs.call_kfunc_xy, &test_opts);
+	test_run_prog(skel->progs.call_kfunc_yx, &test_opts);
+
+	kfunc_module_order__destroy(skel);
+exit_mods:
+	unload_module("bpf_test_modorder_y", env_verbosity > VERBOSE_NONE);
+exit_modx:
+	unload_module("bpf_test_modorder_x", env_verbosity > VERBOSE_NONE);
+}