Add a simple test that validates that libbpf will reject isolated struct_ops program early with helpful warning message. Also validate that explicit use of such BPF program through BPF skeleton after BPF object is open won't trigger any warnings. Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> --- .../bpf/prog_tests/test_struct_ops_module.c | 45 +++++++++++++++++++ .../bpf/progs/struct_ops_forgotten_cb.c | 19 ++++++++ 2 files changed, 64 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_forgotten_cb.c diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c index f3c61ebad323..3785b648c8ad 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c +++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c @@ -5,6 +5,7 @@ #include "struct_ops_module.skel.h" #include "struct_ops_nulled_out_cb.skel.h" +#include "struct_ops_forgotten_cb.skel.h" static void check_map_info(struct bpf_map_info *info) { @@ -199,6 +200,48 @@ static void test_struct_ops_nulled_out_cb(void) struct_ops_nulled_out_cb__destroy(skel); } +/* validate that libbpf generates reasonable error message if struct_ops is + * not referenced in any struct_ops map + */ +static void test_struct_ops_forgotten_cb(void) +{ + struct struct_ops_forgotten_cb *skel; + char *log; + int err; + + skel = struct_ops_forgotten_cb__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return; + + start_libbpf_log_capture(); + + err = struct_ops_forgotten_cb__load(skel); + if (!ASSERT_ERR(err, "skel_load")) + goto cleanup; + + log = stop_libbpf_log_capture(); + ASSERT_HAS_SUBSTR(log, + "prog 'test_1_forgotten': SEC(\"struct_ops\") program isn't referenced anywhere, did you forget to use it?", + "libbpf_log"); + free(log); + + struct_ops_forgotten_cb__destroy(skel); + + /* now let's programmatically use it, we should be fine now */ + skel = struct_ops_forgotten_cb__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return; + + skel->struct_ops.ops->test_1 = skel->progs.test_1_forgotten; /* not anymore */ + + err = struct_ops_forgotten_cb__load(skel); + if (!ASSERT_OK(err, "skel_load")) + goto cleanup; + +cleanup: + struct_ops_forgotten_cb__destroy(skel); +} + void serial_test_struct_ops_module(void) { if (test__start_subtest("test_struct_ops_load")) @@ -209,5 +252,7 @@ void serial_test_struct_ops_module(void) test_struct_ops_incompatible(); if (test__start_subtest("test_struct_ops_null_out_cb")) test_struct_ops_nulled_out_cb(); + if (test__start_subtest("struct_ops_forgotten_cb")) + test_struct_ops_forgotten_cb(); } diff --git a/tools/testing/selftests/bpf/progs/struct_ops_forgotten_cb.c b/tools/testing/selftests/bpf/progs/struct_ops_forgotten_cb.c new file mode 100644 index 000000000000..3c822103bd40 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_forgotten_cb.c @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */ +#include <vmlinux.h> +#include <bpf/bpf_tracing.h> +#include "../bpf_testmod/bpf_testmod.h" + +char _license[] SEC("license") = "GPL"; + +SEC("struct_ops/test_1") +int BPF_PROG(test_1_forgotten) +{ + return 0; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops ops = { + /* we forgot to reference test_1_forgotten above, oops */ +}; + -- 2.43.0