From: David Miller <davem@davemloft.net>
To: andrii.nakryiko@gmail.com
Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, kernel-team@fb.com,
andriin@fb.com, yamada.masahiro@socionext.com, acme@redhat.com,
daniel@iogearbox.net, ast@fb.com, yhs@fb.com, kafai@fb.com
Subject: Re: [PATCH bpf-next] kbuild: add ability to generate BTF type info for vmlinux
Date: Tue, 02 Apr 2019 10:40:30 -0700 (PDT) [thread overview]
Message-ID: <20190402.104030.733182526476732084.davem@davemloft.net> (raw)
In-Reply-To: <20190402164950.429597-1-andrii.nakryiko@gmail.com>
From: <andrii.nakryiko@gmail.com>
Date: Tue, 2 Apr 2019 09:49:50 -0700
> From: Andrii Nakryiko <andriin@fb.com>
>
> This patch adds new config option to trigger generation of BTF type
> information from DWARF debuginfo for vmlinux and kernel modules through
> pahole, which in turn relies on libbpf for btf_dedup() algorithm.
>
> The intent is to record compact type information of all types used
> inside kernel, including all the structs/unions/typedefs/etc. This
> enables BPF's compile-once-run-everywhere ([0]) approach, in which
> tracing programs that are inspecting kernel's internal data (e.g.,
> struct task_struct) can be compiled on a system running some kernel
> version, but would be possible to run on other kernel versions (and
> configurations) without recompilation, even if the layout of structs
> changed and/or some of the fields were added, removed, or renamed.
>
> This is only possible if BPF loader can get kernel type info to adjust
> all the offsets correctly. This patch is a first time in this direction,
> making sure that BTF type info is part of Linux kernel image in
> non-loadable ELF section.
>
> BTF deduplication ([1]) algorithm typically provides 100x savings
> compared to DWARF data, so resulting .BTF section is not big as is
> typically about 2MB in size.
>
> [0] http://vger.kernel.org/lpc-bpf2018.html#session-2
> [1] https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html
>
> Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: David S. Miller <davem@davemloft.net>
next prev parent reply other threads:[~2019-04-02 17:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-02 16:49 [PATCH bpf-next] kbuild: add ability to generate BTF type info for vmlinux andrii.nakryiko
2019-04-02 17:40 ` David Miller [this message]
2019-04-02 23:00 ` Daniel Borkmann
2019-04-03 8:46 ` Jiri Olsa
2019-04-03 9:04 ` Daniel Borkmann
2019-04-03 9:12 ` Jiri Olsa
2019-04-03 9:21 ` Daniel Borkmann
2019-04-03 12:05 ` Arnaldo Carvalho de Melo
2019-04-04 0:40 ` Arnaldo Carvalho de Melo
2019-04-04 8:47 ` Jiri Olsa
-- strict thread matches above, loose matches on Subject: below --
2019-03-15 20:17 Andrii Nakryiko
2019-03-25 15:59 ` Alexei Starovoitov
2019-03-27 1:24 ` Alexei Starovoitov
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