From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Alexei Starovoitov <ast@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Daniel Borkmann <daniel@iogearbox.net>,
"x86@kernel.org" <x86@kernel.org>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH v2 bpf-next 05/12] libbpf: auto-detect btf_id of raw_tracepoint
Date: Fri, 11 Oct 2019 21:38:06 -0700 [thread overview]
Message-ID: <CAEf4BzZsz-6ftv628bk9LtEFr1qUoARL32x-kGagi7esOBURyA@mail.gmail.com> (raw)
In-Reply-To: <ec2ca725-6228-b9e9-e9fc-34e4b34d8a1a@fb.com>
On Fri, Oct 11, 2019 at 6:29 PM Alexei Starovoitov <ast@fb.com> wrote:
>
> On 10/11/19 5:40 PM, Alexei Starovoitov wrote:
> >> But even if kernel supports attach_btf_id, I think users still need to
> >> opt in into specifying attach_btf_id by libbpf. Think about existing
> >> raw_tp programs that are using bpf_probe_read() because they were not
> >> created with this kernel feature in mind. They will suddenly stop
> >> working without any of user's fault.
> >
> > This one is excellent catch.
> > loop1.c should have caught it, since it has
> > SEC("raw_tracepoint/kfree_skb")
> > {
> > int nested_loops(volatile struct pt_regs* ctx)
> > .. = PT_REGS_RC(ctx);
> >
> > and verifier would have rejected it.
> > But the way the test is written it's not using libbpf's autodetect
> > of program type, so everything is passing.
>
> With:
> diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
> b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
> index 1c01ee2600a9..e27156dce10d 100644
> --- a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
> @@ -67,7 +67,7 @@ void test_bpf_verif_scale(void)
> */
> { "pyperf600_nounroll.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
>
> - { "loop1.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
> + { "loop1.o", BPF_PROG_TYPE_UNSPEC},
> { "loop2.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
>
> libbpf prog auto-detection kicks in and ...
> # ./test_progs -n 3/10
> libbpf: load bpf program failed: Permission denied
> libbpf: -- BEGIN DUMP LOG ---
> libbpf:
> raw_tp 'kfree_skb' doesn't have 10-th argument
> invalid bpf_context access off=80 size=8
>
> Good :) The verifier is doing its job.
oh, another super intuitive error from verifier ;) 10th argument, what?..
next prev parent reply other threads:[~2019-10-12 4:38 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-10 4:14 [PATCH v2 bpf-next 00/12] bpf: revolutionize bpf tracing Alexei Starovoitov
2019-10-10 4:14 ` [PATCH v2 bpf-next 01/12] bpf: add typecast to raw_tracepoints to help BTF generation Alexei Starovoitov
2019-10-10 4:14 ` [PATCH v2 bpf-next 02/12] bpf: add typecast to bpf helpers " Alexei Starovoitov
2019-10-10 4:14 ` [PATCH v2 bpf-next 03/12] bpf: process in-kernel BTF Alexei Starovoitov
2019-10-11 17:56 ` Andrii Nakryiko
2019-10-10 4:14 ` [PATCH v2 bpf-next 04/12] bpf: add attach_btf_id attribute to program load Alexei Starovoitov
2019-10-11 17:58 ` Andrii Nakryiko
2019-10-10 4:14 ` [PATCH v2 bpf-next 05/12] libbpf: auto-detect btf_id of raw_tracepoint Alexei Starovoitov
2019-10-11 18:02 ` Andrii Nakryiko
2019-10-11 18:07 ` Andrii Nakryiko
2019-10-12 0:40 ` Alexei Starovoitov
2019-10-12 1:29 ` Alexei Starovoitov
2019-10-12 4:38 ` Andrii Nakryiko [this message]
2019-10-12 4:53 ` Alexei Starovoitov
2019-10-12 4:39 ` Andrii Nakryiko
2019-10-10 4:14 ` [PATCH v2 bpf-next 06/12] bpf: implement accurate raw_tp context access via BTF Alexei Starovoitov
2019-10-11 18:31 ` Andrii Nakryiko
2019-10-11 23:13 ` Andrii Nakryiko
2019-10-10 4:14 ` [PATCH v2 bpf-next 07/12] bpf: attach raw_tp program with BTF via type name Alexei Starovoitov
2019-10-11 18:44 ` Andrii Nakryiko
2019-10-10 4:14 ` [PATCH v2 bpf-next 08/12] bpf: add support for BTF pointers to interpreter Alexei Starovoitov
2019-10-10 4:15 ` [PATCH v2 bpf-next 09/12] bpf: add support for BTF pointers to x86 JIT Alexei Starovoitov
2019-10-11 18:48 ` Andrii Nakryiko
2019-10-10 4:15 ` [PATCH v2 bpf-next 10/12] bpf: check types of arguments passed into helpers Alexei Starovoitov
2019-10-11 19:02 ` Andrii Nakryiko
2019-10-12 1:39 ` Alexei Starovoitov
2019-10-12 4:25 ` Andrii Nakryiko
2019-10-10 4:15 ` [PATCH v2 bpf-next 11/12] bpf: disallow bpf_probe_read[_str] helpers Alexei Starovoitov
2019-10-11 19:03 ` Andrii Nakryiko
2019-10-10 4:15 ` [PATCH v2 bpf-next 12/12] selftests/bpf: add kfree_skb raw_tp test Alexei Starovoitov
2019-10-10 11:07 ` Ido Schimmel
2019-10-10 19:07 ` Alexei Starovoitov
2019-10-11 19:05 ` Andrii Nakryiko
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