Re: [PATCH v3 bpf-next 3/3] selftests/bpf: Add test for attaching kprobe with long event names

Feng Yang
2025-04-15T02:53:49Z

On Mon, 14 Apr 2025 13:47:55 +0200, Jiri Olsa <olsajiri@gmail.com> wrote:

> On Mon, Apr 14, 2025 at 05:34:02PM +0800, Feng Yang wrote:
> > From: Feng Yang <yangfeng@kylinos.cn>
> >
> > This test verifies that attaching kprobe/kretprobe with long event names
> > does not trigger EINVAL errors.
> >
> > Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
> > ---
> > .../selftests/bpf/prog_tests/attach_probe.c | 35 +++++++++++++++++++
> > .../selftests/bpf/test_kmods/bpf_testmod.c | 5 +++
> > .../bpf/test_kmods/bpf_testmod_kfunc.h | 2 ++
> > 3 files changed, 42 insertions(+)
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/attach_probe.c b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> > index 9b7f36f39c32..633b5eb4379b 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> > @@ -168,6 +168,39 @@ static void test_attach_uprobe_long_event_name(void)
> > test_attach_probe_manual__destroy(skel);
> > }
> >
> > +/* attach kprobe/kretprobe long event name testings */
> > +static void test_attach_kprobe_long_event_name(void)
> > +{
> > + DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, kprobe_opts);
> > + struct bpf_link *kprobe_link, *kretprobe_link;
> > + struct test_attach_probe_manual *skel;
> > +
> > + skel = test_attach_probe_manual__open_and_load();
> > + if (!ASSERT_OK_PTR(skel, "skel_kprobe_manual_open_and_load"))
> > + return;
> > +
> > + /* manual-attach kprobe/kretprobe */
> > + kprobe_opts.attach_mode = PROBE_ATTACH_MODE_LEGACY;
> > + kprobe_opts.retprobe = false;
> > + kprobe_link = bpf_program__attach_kprobe_opts(skel->progs.handle_kprobe,
> > + "bpf_kfunc_looooooooooooooooooooooooooooooong_name",
> > + &kprobe_opts);
> > + if (!ASSERT_OK_PTR(kprobe_link, "attach_kprobe_long_event_name"))
> > + goto cleanup;
> > + skel->links.handle_kprobe = kprobe_link;
> > +
> > + kprobe_opts.retprobe = true;
> > + kretprobe_link = bpf_program__attach_kprobe_opts(skel->progs.handle_kretprobe,
> > + "bpf_kfunc_looooooooooooooooooooooooooooooong_name",
> > + &kprobe_opts);
> > + if (!ASSERT_OK_PTR(kretprobe_link, "attach_kretprobe_long_event_name"))
> > + goto cleanup;
> > + skel->links.handle_kretprobe = kretprobe_link;
> > +
> > +cleanup:
> > + test_attach_probe_manual__destroy(skel);
> > +}
> > +
> > static void test_attach_probe_auto(struct test_attach_probe *skel)
> > {
> > struct bpf_link *uprobe_err_link;
> > @@ -371,6 +404,8 @@ void test_attach_probe(void)
> >
> > if (test__start_subtest("uprobe-long_name"))
> > test_attach_uprobe_long_event_name();
> > + if (test__start_subtest("kprobe-long_name"))
> > + test_attach_kprobe_long_event_name();
> >
> > cleanup:
> > test_attach_probe__destroy(skel);
> > diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
> > index f38eaf0d35ef..439f6c2b2456 100644
> > --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
> > +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
> > @@ -1053,6 +1053,10 @@ __bpf_kfunc int bpf_kfunc_st_ops_inc10(struct st_ops_args *args)
> > return args->a;
> > }
> >
> > +__bpf_kfunc void bpf_kfunc_looooooooooooooooooooooooooooooong_name(void)
> > +{
> > +}
>
> does it need to be a kfunc? IIUC it just needs to be a normal kernel/module function
>
> jirka
>

Indeed, so is it okay if I make the following modifications:

--- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
@@ -134,6 +134,10 @@ bpf_testmod_test_arg_ptr_to_struct(struct bpf_testmod_struct_arg_1 *a) {
return bpf_testmod_test_struct_arg_result;
}

+noinline void bpf_testmod_looooooooooooooooooooooooooooooong_name(void)
+{
+}
+
__bpf_kfunc void
bpf_testmod_test_mod_kfunc(int i)

Thanks.

> > +
> > BTF_KFUNCS_START(bpf_testmod_check_kfunc_ids)
> > BTF_ID_FLAGS(func, bpf_testmod_test_mod_kfunc)
> > BTF_ID_FLAGS(func, bpf_kfunc_call_test1)
> > @@ -1093,6 +1097,7 @@ BTF_ID_FLAGS(func, bpf_kfunc_st_ops_test_prologue, KF_TRUSTED_ARGS | KF_SLEEPABL
> > BTF_ID_FLAGS(func, bpf_kfunc_st_ops_test_epilogue, KF_TRUSTED_ARGS | KF_SLEEPABLE)
> > BTF_ID_FLAGS(func, bpf_kfunc_st_ops_test_pro_epilogue, KF_TRUSTED_ARGS | KF_SLEEPABLE)
> > BTF_ID_FLAGS(func, bpf_kfunc_st_ops_inc10, KF_TRUSTED_ARGS)
> > +BTF_ID_FLAGS(func, bpf_kfunc_looooooooooooooooooooooooooooooong_name)
> > BTF_KFUNCS_END(bpf_testmod_check_kfunc_ids)
> >
> > static int bpf_testmod_ops_init(struct btf *btf)
> > diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h b/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h
> > index b58817938deb..e5b833140418 100644
> > --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h
> > +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h
> > @@ -159,4 +159,6 @@ void bpf_kfunc_trusted_task_test(struct task_struct *ptr) __ksym;
> > void bpf_kfunc_trusted_num_test(int *ptr) __ksym;
> > void bpf_kfunc_rcu_task_test(struct task_struct *ptr) __ksym;
> >
> > +void bpf_kfunc_looooooooooooooooooooooooooooooong_name(void) __ksym;
> > +
> > #endif /* _BPF_TESTMOD_KFUNC_H */
> > --
> > 2.43.0
> >