Re: [PATCH bpf-next 7/7] selftests/bpf: Add test for BPF trampoline

From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Alexei Starovoitov <ast@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Peter Ziljstra <peterz@infradead.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	x86@kernel.org, Networking <netdev@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>, Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 7/7] selftests/bpf: Add test for BPF trampoline
Date: Tue, 5 Nov 2019 13:50:19 -0800	[thread overview]
Message-ID: <CAEf4BzZCHGXCAdVNm2MoxrjgXxNHqXrZgw70j=byQuo4LSNQfg@mail.gmail.com> (raw)
In-Reply-To: <20191102220025.2475981-8-ast@kernel.org>

On Sat, Nov 2, 2019 at 3:04 PM Alexei Starovoitov <ast@kernel.org> wrote:
>
> Add sanity test for BPF trampoline that checks kernel functions
> with up to 6 arguments of different sizes.
>
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
> ---
>  tools/lib/bpf/bpf_helpers.h                   | 13 +++
>  .../selftests/bpf/prog_tests/fentry_test.c    | 65 ++++++++++++++
>  .../testing/selftests/bpf/progs/fentry_test.c | 90 +++++++++++++++++++
>  3 files changed, 168 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/fentry_test.c
>  create mode 100644 tools/testing/selftests/bpf/progs/fentry_test.c
>
> diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
> index 0c7d28292898..c63ab1add126 100644
> --- a/tools/lib/bpf/bpf_helpers.h
> +++ b/tools/lib/bpf/bpf_helpers.h
> @@ -44,4 +44,17 @@ enum libbpf_pin_type {
>         LIBBPF_PIN_BY_NAME,
>  };
>
> +/* The following types should be used by BPF_PROG_TYPE_TRACING program to
> + * access kernel function arguments. BPF trampoline and raw tracepoints
> + * typecast arguments to 'unsigned long long'.
> + */
> +typedef int __attribute__((aligned(8))) ks32;
> +typedef char __attribute__((aligned(8))) ks8;
> +typedef short __attribute__((aligned(8))) ks16;
> +typedef long long __attribute__((aligned(8))) ks64;
> +typedef unsigned int __attribute__((aligned(8))) ku32;
> +typedef unsigned char __attribute__((aligned(8))) ku8;
> +typedef unsigned short __attribute__((aligned(8))) ku16;
> +typedef unsigned long long __attribute__((aligned(8))) ku64;
> +
>  #endif

[...]

> +
> +       err = bpf_prog_load("./test_pkt_access.o", BPF_PROG_TYPE_SCHED_CLS,
> +                           &pkt_obj, &pkt_fd);
> +       if (CHECK(err, "prog_load sched cls", "err %d errno %d\n", err, errno))
> +               return;
> +       err = bpf_prog_load_xattr(&attr, &obj, &kfree_skb_fd);
> +       if (CHECK(err, "prog_load fail", "err %d errno %d\n", err, errno))
> +               goto close_prog;
> +
> +       for (i = 0; i < 6; i++) {
> +               prog_name[sizeof(prog_name) - 2] = '1' + i;
> +               prog[i] = bpf_object__find_program_by_title(obj, prog_name);
> +               if (CHECK(!prog[i], "find_prog", "prog %s not found\n", prog_name))
> +                       goto close_prog;
> +               link[i] = bpf_program__attach_trace(prog[i]);

CHECK() here?

> +       }
> +       data_map = bpf_object__find_map_by_name(obj, "fentry_t.bss");
> +       if (CHECK(!data_map, "find_data_map", "data map not found\n"))
> +               goto close_prog;
> +
> +       err = bpf_prog_test_run(pkt_fd, 1, &pkt_v6, sizeof(pkt_v6),
> +                               NULL, NULL, &retval, &duration);
> +       CHECK(err || retval, "ipv6",
> +             "err %d errno %d retval %d duration %d\n",
> +             err, errno, retval, duration);
> +
> +       err = bpf_map_lookup_elem(bpf_map__fd(data_map), &zero, &result);
> +       if (CHECK(err, "get_result",
> +                 "failed to get output data: %d\n", err))
> +               goto close_prog;
> +
> +       for (i = 0; i < 6; i++)
> +               if (CHECK(result[i] != 1, "result", "bpf_fentry_test%d failed err %ld\n",
> +                         i + 1, result[i]))
> +                       goto close_prog;
> +
> +       passed = true;
> +       CHECK_FAIL(!passed);

passed and CHECK_FAIL are completely redundant?

> +close_prog:
> +       for (i = 0; i < 6; i++)
> +               if (!IS_ERR_OR_NULL(link[i]))
> +                       bpf_link__destroy(link[i]);
> +       bpf_object__close(obj);
> +       bpf_object__close(pkt_obj);
> +}

[...]