linux-kernel - Re: [PATCH 8/8] selftest/bpf: Add fprobe test for bpf

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Date:   Mon, 7 Feb 2022 10:59:32 -0800
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Jiri Olsa <olsajiri@...il.com>
Subject: Re: [PATCH 8/8] selftest/bpf: Add fprobe test for bpf_cookie values

On Wed, Feb 2, 2022 at 5:54 AM Jiri Olsa <jolsa@...hat.com> wrote:
>
> Adding bpf_cookie test for kprobe attached by fprobe link.
>
> Signed-off-by: Jiri Olsa <jolsa@...nel.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.

> +       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?

> +               fprobe_subtest();
>         if (test__start_subtest("uprobe"))
>                 uprobe_subtest(skel);
>         if (test__start_subtest("tracepoint"))

[...]