Re: [PATCH 8/8] selftest/bpf: Add fprobe test for bpf_cookie values

Andrii Nakryiko
2022-02-08T23:24:27Z

On Tue, Feb 8, 2022 at 1:16 AM Jiri Olsa <jolsa@redhat.com> wrote:
>
> On Mon, Feb 07, 2022 at 10:59:32AM -0800, Andrii Nakryiko wrote:
> > On Wed, Feb 2, 2022 at 5:54 AM Jiri Olsa <jolsa@redhat.com> wrote:
> > >
> > > Adding bpf_cookie test for kprobe attached by fprobe link.
> > >
> > > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > > ---
> > > .../selftests/bpf/prog_tests/bpf_cookie.c | 73 +++++++++++++++++++
> > > .../selftests/bpf/progs/fprobe_bpf_cookie.c | 62 ++++++++++++++++
> > > 2 files changed, 135 insertions(+)
> > > create mode 100644 tools/testing/selftests/bpf/progs/fprobe_bpf_cookie.c
> > >
> > > diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c b/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c
> > > index cd10df6cd0fc..bf70d859c598 100644
> > > --- a/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c
> > > +++ b/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c
> > > @@ -7,6 +7,7 @@
> > > #include <unistd.h>
> > > #include <test_progs.h>
> > > #include "test_bpf_cookie.skel.h"
> > > +#include "fprobe_bpf_cookie.skel.h"
> > >
> > > /* uprobe attach point */
> > > static void trigger_func(void)
> > > @@ -63,6 +64,76 @@ static void kprobe_subtest(struct test_bpf_cookie *skel)
> > > bpf_link__destroy(retlink2);
> > > }
> > >
> > > +static void fprobe_subtest(void)
> > > +{
> > > + DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts);
> > > + int err, prog_fd, link1_fd = -1, link2_fd = -1;
> > > + struct fprobe_bpf_cookie *skel = NULL;
> > > + __u32 duration = 0, retval;
> > > + __u64 addrs[8], cookies[8];
> > > +
> > > + skel = fprobe_bpf_cookie__open_and_load();
> > > + if (!ASSERT_OK_PTR(skel, "fentry_raw_skel_load"))
> > > + goto cleanup;
> > > +
> > > + kallsyms_find("bpf_fentry_test1", &addrs[0]);
> > > + kallsyms_find("bpf_fentry_test2", &addrs[1]);
> > > + kallsyms_find("bpf_fentry_test3", &addrs[2]);
> > > + kallsyms_find("bpf_fentry_test4", &addrs[3]);
> > > + kallsyms_find("bpf_fentry_test5", &addrs[4]);
> > > + kallsyms_find("bpf_fentry_test6", &addrs[5]);
> > > + kallsyms_find("bpf_fentry_test7", &addrs[6]);
> > > + kallsyms_find("bpf_fentry_test8", &addrs[7]);
> > > +
> > > + cookies[0] = 1;
> > > + cookies[1] = 2;
> > > + cookies[2] = 3;
> > > + cookies[3] = 4;
> > > + cookies[4] = 5;
> > > + cookies[5] = 6;
> > > + cookies[6] = 7;
> > > + cookies[7] = 8;
> > > +
> > > + opts.fprobe.addrs = (__u64) &addrs;
> >
> > we should have ptr_to_u64() for test_progs, but if not, let's either
> > add it or it should be (__u64)(uintptr_t)&addrs. Otherwise we'll be
> > getting compilation warnings on some architectures.
>
> there's one in btf.c, bpf.c and libbpf.c ;-) so I guess it could go to bpf.h

No, it shouldn't, bpf.h is a public API header. Let's keep internal
helpers internal. Just copy/paste.

>
> >
> > > + opts.fprobe.cnt = 8;
> > > + opts.fprobe.bpf_cookies = (__u64) &cookies;
> > > + prog_fd = bpf_program__fd(skel->progs.test2);
> > > +
> > > + link1_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_FPROBE, &opts);
> > > + if (!ASSERT_GE(link1_fd, 0, "link1_fd"))
> > > + return;
> > > +
> > > + cookies[0] = 8;
> > > + cookies[1] = 7;
> > > + cookies[2] = 6;
> > > + cookies[3] = 5;
> > > + cookies[4] = 4;
> > > + cookies[5] = 3;
> > > + cookies[6] = 2;
> > > + cookies[7] = 1;
> > > +
> > > + opts.flags = BPF_F_FPROBE_RETURN;
> > > + prog_fd = bpf_program__fd(skel->progs.test3);
> > > +
> > > + link2_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_FPROBE, &opts);
> > > + if (!ASSERT_GE(link2_fd, 0, "link2_fd"))
> > > + goto cleanup;
> > > +
> > > + prog_fd = bpf_program__fd(skel->progs.test1);
> > > + err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
> > > + NULL, NULL, &retval, &duration);
> > > + ASSERT_OK(err, "test_run");
> > > + ASSERT_EQ(retval, 0, "test_run");
> > > +
> > > + ASSERT_EQ(skel->bss->test2_result, 8, "test2_result");
> > > + ASSERT_EQ(skel->bss->test3_result, 8, "test3_result");
> > > +
> > > +cleanup:
> > > + close(link1_fd);
> > > + close(link2_fd);
> > > + fprobe_bpf_cookie__destroy(skel);
> > > +}
> > > +
> > > static void uprobe_subtest(struct test_bpf_cookie *skel)
> > > {
> > > DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts);
> > > @@ -249,6 +320,8 @@ void test_bpf_cookie(void)
> > >
> > > if (test__start_subtest("kprobe"))
> > > kprobe_subtest(skel);
> > > + if (test__start_subtest("rawkprobe"))
> >
> > kprobe.multi?
>
> yes
>
> thanks,
> jirka
>