1 files changed, 100 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
new file mode 100644
index 0000000000..6cd7349d4a
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define _GNU_SOURCE
+#include <test_progs.h>
+
+struct inst {
+	struct bpf_object *obj;
+	struct bpf_link   *link;
+};
+
+static struct bpf_program *load_prog(char *file, char *name, struct inst *inst)
+{
+	struct bpf_object *obj;
+	struct bpf_program *prog;
+	int err;
+
+	obj = bpf_object__open_file(file, NULL);
+	if (!ASSERT_OK_PTR(obj, "obj_open_file"))
+		return NULL;
+
+	inst->obj = obj;
+
+	err = bpf_object__load(obj);
+	if (!ASSERT_OK(err, "obj_load"))
+		return NULL;
+
+	prog = bpf_object__find_program_by_name(obj, name);
+	if (!ASSERT_OK_PTR(prog, "obj_find_prog"))
+		return NULL;
+
+	return prog;
+}
+
+/* TODO: use different target function to run in concurrent mode */
+void serial_test_trampoline_count(void)
+{
+	char *file = "test_trampoline_count.bpf.o";
+	char *const progs[] = { "fentry_test", "fmod_ret_test", "fexit_test" };
+	int bpf_max_tramp_links, err, i, prog_fd;
+	struct bpf_program *prog;
+	struct bpf_link *link;
+	struct inst *inst;
+	LIBBPF_OPTS(bpf_test_run_opts, opts);
+
+	bpf_max_tramp_links = get_bpf_max_tramp_links();
+	if (!ASSERT_GE(bpf_max_tramp_links, 1, "bpf_max_tramp_links"))
+		return;
+	inst = calloc(bpf_max_tramp_links + 1, sizeof(*inst));
+	if (!ASSERT_OK_PTR(inst, "inst"))
+		return;
+
+	/* attach 'allowed' trampoline programs */
+	for (i = 0; i < bpf_max_tramp_links; i++) {
+		prog = load_prog(file, progs[i % ARRAY_SIZE(progs)], &inst[i]);
+		if (!prog)
+			goto cleanup;
+
+		link = bpf_program__attach(prog);
+		if (!ASSERT_OK_PTR(link, "attach_prog"))
+			goto cleanup;
+
+		inst[i].link = link;
+	}
+
+	/* and try 1 extra.. */
+	prog = load_prog(file, "fmod_ret_test", &inst[i]);
+	if (!prog)
+		goto cleanup;
+
+	/* ..that needs to fail */
+	link = bpf_program__attach(prog);
+	if (!ASSERT_ERR_PTR(link, "attach_prog")) {
+		inst[i].link = link;
+		goto cleanup;
+	}
+
+	/* with E2BIG error */
+	if (!ASSERT_EQ(libbpf_get_error(link), -E2BIG, "E2BIG"))
+		goto cleanup;
+	if (!ASSERT_EQ(link, NULL, "ptr_is_null"))
+		goto cleanup;
+
+	/* and finally execute the probe */
+	prog_fd = bpf_program__fd(prog);
+	if (!ASSERT_GE(prog_fd, 0, "bpf_program__fd"))
+		goto cleanup;
+
+	err = bpf_prog_test_run_opts(prog_fd, &opts);
+	if (!ASSERT_OK(err, "bpf_prog_test_run_opts"))
+		goto cleanup;
+
+	ASSERT_EQ(opts.retval & 0xffff, 33, "bpf_modify_return_test.result");
+	ASSERT_EQ(opts.retval >> 16, 2, "bpf_modify_return_test.side_effect");
+
+cleanup:
+	for (; i >= 0; i--) {
+		bpf_link__destroy(inst[i].link);
+		bpf_object__close(inst[i].obj);
+	}
+	free(inst);
+}