From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <netdev-owner@vger.kernel.org>
Received: from mail-pg0-f50.google.com ([74.125.83.50]:37880 "EHLO
        mail-pg0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751663AbeB0EZa (ORCPT
        <rfc822;netdev@vger.kernel.org>); Mon, 26 Feb 2018 23:25:30 -0500
Received: by mail-pg0-f50.google.com with SMTP id y26so7081602pgv.4
        for <netdev@vger.kernel.org>; Mon, 26 Feb 2018 20:25:30 -0800 (PST)
Date: Mon, 26 Feb 2018 20:25:27 -0800
From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: daniel@iogearbox.net, netdev@vger.kernel.org,
        oss-drivers@netronome.com, Jiong Wang <jiong.wang@netronome.com>
Subject: Re: [PATCH bpf-next 3/8] tools: bpftool: detect sub-programs from
 the eBPF sequence
Message-ID: <20180227042525.gbfn3ul4baghipcv@ast-mbp>
References: <20180227041254.32442-1-jakub.kicinski@netronome.com>
 <20180227041254.32442-4-jakub.kicinski@netronome.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20180227041254.32442-4-jakub.kicinski@netronome.com>
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

On Mon, Feb 26, 2018 at 08:12:49PM -0800, Jakub Kicinski wrote:
> From: Jiong Wang <jiong.wang@netronome.com>
> 
> This patch detect all sub-programs from the eBPF sequence and keep the
> information in the new CFG data structure.
> 
> The detection algorithm is basically the same as the one in verifier except
> we need to use insn->off instead of insn->imm to get the pc-relative call
> offset. Because verifier has modified insn->off/insn->imm during finishing
> the verification.
> 
> Also, we don't need to do some sanity checks as verifier has done them.
> 
> Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
> Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>

overall idea looks good to me.
One step towards proper decompiler ;)

> diff --git a/tools/bpf/bpftool/cfg.c b/tools/bpf/bpftool/cfg.c
> new file mode 100644
> index 000000000000..42a0d4c4271c
> --- /dev/null
> +++ b/tools/bpf/bpftool/cfg.c
> @@ -0,0 +1,143 @@
> +/*
> + * Copyright (C) 2018 Netronome Systems, Inc.
> + *
> + * This software is dual licensed under the GNU General License Version 2,
> + * June 1991 as shown in the file COPYING in the top-level directory of this
> + * source tree or the BSD 2-Clause License provided below.  You have the
> + * option to license this software under the complete terms of either license.

please use SPDX instead.