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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Stanislav Fomichev <sdf@fomichev.me>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	Stanislav Fomichev <sdf@google.com>,
	Network Development <netdev@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Yonghong Song <yhs@fb.com>
Subject: Re: debug annotations for bpf progs. Was: [PATCH bpf-next 1/3] bpf: preserve command of the process that loaded the program
Date: Thu, 17 Oct 2019 23:19:47 -0700
Message-ID: <CAADnVQKWN87F=xnbBwwm+B04rt5HTRRmwMjepqWrgsxuS+sPHA@mail.gmail.com> (raw)
In-Reply-To: <20191017162843.GB2090@mini-arch>

On Thu, Oct 17, 2019 at 9:28 AM Stanislav Fomichev <sdf@fomichev.me> wrote:
> Tried to do the following:
>
> 1. Add: static volatile const char __annotate_source1[] = __FILE__;
>    to test_rdonly_maps.c and I think it got optimized away :-/
>    At least I don't see it in the 'bpftool btf dump' output.
>
> 2. Add: char __annotate_source2[] SEC(".meta") = __FILE__;
>    to test_rdonly_maps.c and do all the required plumbing in libbpf
>    to treat .meta like .rodata. I think it works, but the map
>    disappears after bpftool exits because this data is not referenced
>    in the prog and the refcount drops to zero :-(
>
> Am I missing something?

"Some assembly required".

I think first variant should work at the end.
I don't think extra section should be a requirement.
Sounds like with 2 it's pretty close. Just need to make sure
that prog side sees the map as referenced.
And more importantly bpftool can find that map from prog later.

      reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-11 16:21 Stanislav Fomichev
2019-10-11 16:21 ` [PATCH bpf-next 2/3] tools/bpf: sync bpf.h Stanislav Fomichev
2019-10-11 16:21 ` [PATCH bpf-next 3/3] bpftool: print the comm of the process that loaded the program Stanislav Fomichev
2019-10-11 20:19   ` Martin Lau
2019-10-11 20:37     ` Stanislav Fomichev
2019-10-11 21:11       ` Arnaldo Carvalho de Melo
2019-10-11 21:30         ` Stanislav Fomichev
2019-10-12  0:10 ` [PATCH bpf-next 1/3] bpf: preserve command " Alexei Starovoitov
2019-10-12  0:38   ` Stanislav Fomichev
2019-10-15 21:21     ` debug annotations for bpf progs. Was: " Alexei Starovoitov
2019-10-15 22:14       ` Andrii Nakryiko
2019-10-15 22:24         ` Alexei Starovoitov
2019-10-15 22:33           ` Andrii Nakryiko
2019-10-15 22:48             ` Alexei Starovoitov
2019-10-15 22:26       ` Stanislav Fomichev
2019-10-16 14:01       ` Daniel Borkmann
2019-10-17 16:28         ` Stanislav Fomichev
2019-10-18  6:19           ` Alexei Starovoitov [this message]

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