netdev - Re: bpf debug info

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Message-ID: <20161206151201.GD2399@kernel.org>
Date:   Tue, 6 Dec 2016 12:12:01 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org,
        Brenden Blanco <bblanco@...mgrid.com>,
        Thomas Graf <tgraf@...g.ch>, Wangnan <wangnan0@...wei.com>,
        He Kuang <hekuang@...wei.com>, kernel-team@...com
Subject: Re: bpf debug info

Em Tue, Nov 29, 2016 at 09:01:17AM -0800, Alexei Starovoitov escreveu:
> On Tue, Nov 29, 2016 at 04:11:32PM +0100, Daniel Borkmann wrote:
> > On 11/29/2016 07:42 AM, Alexei Starovoitov wrote:
> > >Notice that 'clang -S -o a.s' output and llvm-objdump disassembler
> > >were changed to use kernel verifier style, so now it should be easier
> > >to see what's going on.

> > Sounds really useful, is that scheduled for llvm 3.10 release?

> llvm 4.0 :)

> > That debugging info is stored in dwarf format into the obj, right?

> right.

> > Would be nice if also pahole could work on bpf object files.
> 
> yeah. pahole need to be taught to recognize bpf e_machine type and relocations.

Coincidentally I'm testing some perf patches wrt builtin BPF and for
that I'm updating to llvm to 4.0, will take a look at what is involved
in that...

- Arnaldo