Re: [PATCH bpf-next v4 2/2] selftests/bpf: add test for raw-address single kprobe attach

[Hoyeon Lee]

On Wed, Apr 1, 2026 at 8:06 AM Andrii Nakryiko
<andrii.nakryiko@xxxxxxxxx> wrote:
>
> On Tue, Mar 31, 2026 at 8:25 AM Hoyeon Lee <hoyeon.lee@xxxxxxxx> wrote:
> >
> > Currently, attach_probe covers manual single-kprobe attaches by
> > func_name, but not the raw-address form that the PMU-based
> > single-kprobe path can accept.
> >
> > This commit adds PERF and LINK raw-address subtests by resolving
> > SYS_NANOSLEEP_KPROBE_NAME through kallsyms, passing the absolute address
> > in bpf_kprobe_opts.offset with func_name = NULL, and verifying that
> > kprobe and kretprobe are still triggered. It also verifies that LEGACY
> > rejects the same form.
> >
> > Signed-off-by: Hoyeon Lee <hoyeon.lee@xxxxxxxx>
> > ---
> >  .../selftests/bpf/prog_tests/attach_probe.c   | 82 +++++++++++++++++++
> >  1 file changed, 82 insertions(+)
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/attach_probe.c b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> > index 9e77e5da7097..817c4794d54e 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> > @@ -123,6 +123,82 @@ static void test_attach_probe_manual(enum probe_attach_mode attach_mode)
> >         test_attach_probe_manual__destroy(skel);
> >  }
> >
> > +/* manual attach address-based kprobe/kretprobe testings */
> > +static void test_attach_kprobe_by_addr(enum probe_attach_mode attach_mode)
> > +{
> > +       DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, kprobe_opts);
>
> DECLARE_LIBBPF_OPTS is a legacy backwards-compatibility macro, prefer
> using shorter LIBBPF_OPTS
>

Got it, I'll switch to LIBBPF_OPTS and updated the reject
expectation to -EOPNOTSUPP in v5.

> > +       struct test_attach_probe_manual *skel;
> > +       unsigned long func_addr;
> > +
> > +       if (!ASSERT_OK(load_kallsyms(), "load_kallsyms"))
> > +               return;
> > +
> > +       func_addr = ksym_get_addr(SYS_NANOSLEEP_KPROBE_NAME);
> > +       if (!ASSERT_NEQ(func_addr, 0UL, "func_addr"))
> > +               return;
> > +
> > +       skel = test_attach_probe_manual__open_and_load();
> > +       if (!ASSERT_OK_PTR(skel, "skel_kprobe_manual_open_and_load"))
> > +               return;
> > +
> > +       kprobe_opts.attach_mode = attach_mode;
> > +       kprobe_opts.retprobe = false;
> > +       kprobe_opts.offset = func_addr;
> > +       skel->links.handle_kprobe =
> > +               bpf_program__attach_kprobe_opts(skel->progs.handle_kprobe,
> > +                                               NULL, &kprobe_opts);
> > +       if (!ASSERT_OK_PTR(skel->links.handle_kprobe, "attach_kprobe_by_addr"))
> > +               goto cleanup;
> > +
> > +       kprobe_opts.retprobe = true;
> > +       skel->links.handle_kretprobe =
> > +               bpf_program__attach_kprobe_opts(skel->progs.handle_kretprobe,
> > +                                               NULL, &kprobe_opts);
> > +       if (!ASSERT_OK_PTR(skel->links.handle_kretprobe,
> > +                          "attach_kretprobe_by_addr"))
> > +               goto cleanup;
> > +
> > +       /* trigger & validate kprobe && kretprobe */
> > +       usleep(1);
> > +
> > +       ASSERT_EQ(skel->bss->kprobe_res, 1, "check_kprobe_res");
> > +       ASSERT_EQ(skel->bss->kretprobe_res, 2, "check_kretprobe_res");
> > +
> > +cleanup:
> > +       test_attach_probe_manual__destroy(skel);
> > +}
> > +
> > +/* reject legacy address-based kprobe attach */
> > +static void test_attach_kprobe_legacy_by_addr_reject(void)
> > +{
> > +       DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, kprobe_opts);
> > +       struct test_attach_probe_manual *skel;
> > +       unsigned long func_addr;
> > +
> > +       if (!ASSERT_OK(load_kallsyms(), "load_kallsyms"))
> > +               return;
> > +
> > +       func_addr = ksym_get_addr(SYS_NANOSLEEP_KPROBE_NAME);
> > +       if (!ASSERT_NEQ(func_addr, 0UL, "func_addr"))
> > +               return;
> > +
> > +       skel = test_attach_probe_manual__open_and_load();
> > +       if (!ASSERT_OK_PTR(skel, "skel_kprobe_manual_open_and_load"))
> > +               return;
> > +
> > +       kprobe_opts.attach_mode = PROBE_ATTACH_MODE_LEGACY;
> > +       kprobe_opts.offset = func_addr;
> > +       skel->links.handle_kprobe =
> > +               bpf_program__attach_kprobe_opts(skel->progs.handle_kprobe,
> > +                                               NULL, &kprobe_opts);
> > +       if (ASSERT_ERR_PTR(skel->links.handle_kprobe,
> > +                          "attach_kprobe_legacy_by_addr"))
> > +               ASSERT_EQ(libbpf_get_error(skel->links.handle_kprobe), -ENOTSUP,
> > +                         "attach_kprobe_legacy_by_addr_err");
> > +
> > +       test_attach_probe_manual__destroy(skel);
> > +}
> > +
> >  /* attach uprobe/uretprobe long event name testings */
> >  static void test_attach_uprobe_long_event_name(void)
> >  {
> > @@ -416,6 +492,12 @@ void test_attach_probe(void)
> >                 test_attach_probe_manual(PROBE_ATTACH_MODE_PERF);
> >         if (test__start_subtest("manual-link"))
> >                 test_attach_probe_manual(PROBE_ATTACH_MODE_LINK);
> > +       if (test__start_subtest("kprobe-perf-by-addr"))
> > +               test_attach_kprobe_by_addr(PROBE_ATTACH_MODE_PERF);
> > +       if (test__start_subtest("kprobe-link-by-addr"))
> > +               test_attach_kprobe_by_addr(PROBE_ATTACH_MODE_LINK);
> > +       if (test__start_subtest("kprobe-legacy-by-addr-reject"))
> > +               test_attach_kprobe_legacy_by_addr_reject();
> >
> >         if (test__start_subtest("auto"))
> >                 test_attach_probe_auto(skel);
> > --
> > 2.52.0
> >