Re: [PATCH bpf-next 6/7] bpf: Add test ops for BPF_PROG_TYPE_TRACING

[Andrii Nakryiko]

On Tue, Mar 3, 2020 at 6:12 AM KP Singh <kpsingh@xxxxxxxxxxxx> wrote:
>
> From: KP Singh <kpsingh@xxxxxxxxxx>
>
> The current fexit and fentry tests rely on a different program to
> exercise the functions they attach to. Instead of doing this, implement
> the test operations for tracing which will also be used for
> BPF_OVERRIDE_RETURN in a subsequent patch.

typo: BPF_OVERRIDE_RETURN -> BPF_MODIFY_RETURN?

>
> Also, clean up the fexit test to use the generated skeleton.
>
> Signed-off-by: KP Singh <kpsingh@xxxxxxxxxx>
> ---

Nice clean up for fexit_test, thank you!

>  include/linux/bpf.h                           | 10 +++
>  kernel/trace/bpf_trace.c                      |  1 +
>  net/bpf/test_run.c                            | 38 +++++++---
>  .../selftests/bpf/prog_tests/fentry_fexit.c   | 12 +---
>  .../selftests/bpf/prog_tests/fentry_test.c    | 14 ++--
>  .../selftests/bpf/prog_tests/fexit_test.c     | 69 ++++++-------------
>  6 files changed, 68 insertions(+), 76 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 3cfdc216a2f4..c00919025532 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1156,6 +1156,9 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
>                           union bpf_attr __user *uattr);
>  int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
>                           union bpf_attr __user *uattr);
> +int bpf_prog_test_run_tracing(struct bpf_prog *prog,
> +                             const union bpf_attr *kattr,
> +                             union bpf_attr __user *uattr);
>  int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
>                                      const union bpf_attr *kattr,
>                                      union bpf_attr __user *uattr);
> @@ -1313,6 +1316,13 @@ static inline int bpf_prog_test_run_skb(struct bpf_prog *prog,
>         return -ENOTSUPP;
>  }
>
> +static inline int bpf_prog_test_run_tracing(struct bpf_prog *prog,
> +                                           const union bpf_attr *kattr,
> +                                           union bpf_attr __user *uattr)
> +{
> +       return -ENOTSUPP;
> +}
> +
>  static inline int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
>                                                    const union bpf_attr *kattr,
>                                                    union bpf_attr __user *uattr)
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 07764c761073..363e0a2c75cf 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1266,6 +1266,7 @@ const struct bpf_verifier_ops tracing_verifier_ops = {
>  };
>
>  const struct bpf_prog_ops tracing_prog_ops = {
> +       .test_run = bpf_prog_test_run_tracing,
>  };
>
>  static bool raw_tp_writable_prog_is_valid_access(int off, int size,
> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> index 562443f94133..fb54b45285b4 100644
> --- a/net/bpf/test_run.c
> +++ b/net/bpf/test_run.c
> @@ -160,18 +160,38 @@ static void *bpf_test_init(const union bpf_attr *kattr, u32 size,
>                 kfree(data);
>                 return ERR_PTR(-EFAULT);
>         }
> -       if (bpf_fentry_test1(1) != 2 ||
> -           bpf_fentry_test2(2, 3) != 5 ||
> -           bpf_fentry_test3(4, 5, 6) != 15 ||
> -           bpf_fentry_test4((void *)7, 8, 9, 10) != 34 ||
> -           bpf_fentry_test5(11, (void *)12, 13, 14, 15) != 65 ||
> -           bpf_fentry_test6(16, (void *)17, 18, 19, (void *)20, 21) != 111) {
> -               kfree(data);
> -               return ERR_PTR(-EFAULT);
> -       }
> +
>         return data;
>  }
>
> +int bpf_prog_test_run_tracing(struct bpf_prog *prog,
> +                             const union bpf_attr *kattr,
> +                             union bpf_attr __user *uattr)
> +{
> +       int err = -EFAULT;
> +
> +       switch (prog->expected_attach_type) {
> +       case BPF_TRACE_FENTRY:
> +       case BPF_TRACE_FEXIT:
> +               if (bpf_fentry_test1(1) != 2 ||
> +                   bpf_fentry_test2(2, 3) != 5 ||
> +                   bpf_fentry_test3(4, 5, 6) != 15 ||
> +                   bpf_fentry_test4((void *)7, 8, 9, 10) != 34 ||
> +                   bpf_fentry_test5(11, (void *)12, 13, 14, 15) != 65 ||
> +                   bpf_fentry_test6(16, (void *)17, 18, 19, (void *)20, 21) != 111)
> +                       goto out;
> +               break;
> +       default:
> +               goto out;
> +       }

No trace_bpf_test_finish here?

> +
> +       return 0;
> +
> +out:
> +       trace_bpf_test_finish(&err);
> +       return err;
> +}
> +
>  static void *bpf_ctx_init(const union bpf_attr *kattr, u32 max_size)
>  {
>         void __user *data_in = u64_to_user_ptr(kattr->test.ctx_in);

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