netdev - Re: [PATCH v4 bpf-next 3/3] selftests/bpf: add raw_tp_test

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Message-ID: <CAEf4BzYtq3X3kma2Hd-OfkK=D9DeaxhD77dq2V73gj9aOWOrMQ@mail.gmail.com>
Date:   Thu, 24 Sep 2020 13:09:21 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Song Liu <songliubraving@...com>
Cc:     Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Kernel Team <kernel-team@...com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        john fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>
Subject: Re: [PATCH v4 bpf-next 3/3] selftests/bpf: add raw_tp_test_run

On Wed, Sep 23, 2020 at 6:55 PM Song Liu <songliubraving@...com> wrote:
>
> This test runs test_run for raw_tracepoint program. The test covers ctx
> input, retval output, and running on correct cpu.
>
> Signed-off-by: Song Liu <songliubraving@...com>
> ---
>  .../bpf/prog_tests/raw_tp_test_run.c          | 79 +++++++++++++++++++
>  .../bpf/progs/test_raw_tp_test_run.c          | 25 ++++++
>  2 files changed, 104 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_test_run.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_raw_tp_test_run.c
>

[...]

> +       test_attr.ctx_size_in = sizeof(args);
> +       err = bpf_prog_test_run_xattr(&test_attr);
> +       CHECK(err < 0, "test_run", "err %d\n", errno);
> +       CHECK(test_attr.retval != expected_retval, "check_retval",
> +             "expect 0x%x, got 0x%x\n", expected_retval, test_attr.retval);
> +
> +       for (i = 0; i < nr_online; i++)

nit: this for loop is so multi-line that it deserves {}

> +               if (online[i]) {
> +                       DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
> +                               .ctx_in = args,
> +                               .ctx_size_in = sizeof(args),
> +                               .flags = BPF_F_TEST_RUN_ON_CPU,
> +                               .retval = 0,
> +                               .cpu = i,
> +                       );
> +
> +                       err = bpf_prog_test_run_opts(
> +                               bpf_program__fd(skel->progs.rename), &opts);
> +                       CHECK(err < 0, "test_run_opts", "err %d\n", errno);
> +                       CHECK(skel->data->on_cpu != i, "check_on_cpu",
> +                             "expect %d got %d\n", i, skel->data->on_cpu);
> +                       CHECK(opts.retval != expected_retval,
> +                             "check_retval", "expect 0x%x, got 0x%x\n",
> +                             expected_retval, opts.retval);
> +               }

as I mentioned in the first patch, let's have a test specifying
ridiculous CPU and see if it properly fails and doesn't cause any
kernel warning

> +cleanup:
> +       close(comm_fd);
> +       test_raw_tp_test_run__destroy(skel);
> +       free(online);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_raw_tp_test_run.c b/tools/testing/selftests/bpf/progs/test_raw_tp_test_run.c
> new file mode 100644
> index 0000000000000..6b356e003d16c
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_raw_tp_test_run.c
> @@ -0,0 +1,25 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Facebook */
> +
> +#include "vmlinux.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_endian.h>

nit: you don't need bpf_endian.h here, do you?

> +#include <bpf/bpf_tracing.h>
> +
> +__u32 count = 0;
> +__u32 on_cpu = 0xffffffff;
> +
> +SEC("raw_tp/task_rename")
> +int BPF_PROG(rename, struct task_struct *task, char *comm)
> +{
> +
> +       count++;
> +       if ((__u64) task == 0x1234ULL && (__u64) comm == 0x5678ULL) {
> +               on_cpu = bpf_get_smp_processor_id();
> +               return (int)task + (int)comm;
> +       }
> +
> +       return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> --
> 2.24.1
>