From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 05635FC6194 for ; Wed, 6 Nov 2019 23:08:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C641920869 for ; Wed, 6 Nov 2019 23:08:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727646AbfKFXIF (ORCPT ); Wed, 6 Nov 2019 18:08:05 -0500 Received: from www62.your-server.de ([213.133.104.62]:35112 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727080AbfKFXIF (ORCPT ); Wed, 6 Nov 2019 18:08:05 -0500 Received: from sslproxy06.your-server.de ([78.46.172.3]) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1iSUP9-0000W7-Oi; Thu, 07 Nov 2019 00:07:59 +0100 Received: from [178.197.248.39] (helo=pc-63.home) by sslproxy06.your-server.de with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1iSUP9-000OX5-FQ; Thu, 07 Nov 2019 00:07:59 +0100 Subject: Re: [RFC PATCH bpf-next] bpf: allow JIT debugging if CONFIG_BPF_JIT_ALWAYS_ON is set To: John Fastabend , Ilya Leoshkevich , Alexei Starovoitov Cc: Alexei Starovoitov , bpf , Heiko Carstens , Vasily Gorbik References: <20191106161204.87261-1-iii@linux.ibm.com> <10A60D54-07EB-4B5D-AD3B-59C6D8D7CF9D@linux.ibm.com> <5dc2f9cbb002d_23152aba75b6a5bcfd@john-XPS-13-9370.notmuch> From: Daniel Borkmann Message-ID: <2d4334ad-545d-13b6-224a-14420e1da4c0@iogearbox.net> Date: Thu, 7 Nov 2019 00:07:58 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <5dc2f9cbb002d_23152aba75b6a5bcfd@john-XPS-13-9370.notmuch> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.101.4/25625/Wed Nov 6 10:44:04 2019) Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 11/6/19 5:50 PM, John Fastabend wrote: > Ilya Leoshkevich wrote: >>> Am 06.11.2019 um 17:15 schrieb Alexei Starovoitov : >>> On Wed, Nov 6, 2019 at 8:12 AM Ilya Leoshkevich wrote: >>>> >>>> Currently it's not possible to set bpf_jit_enable = 2 when >>>> CONFIG_BPF_JIT_ALWAYS_ON is set, which makes debugging certain problems >>>> harder. >>> >>> This is obsolete way of debugging. >>> Please use bpftool dump jited instead. >> >> Is there a way to integrate bpftool nicely with e.g. test_verifier? >> With bpf_jit_enable = 2, I can see JITed code for each test right away, >> without pausing it (via gdb or rebuilding with added sleep()) and >> running bpftool. > > On the library side we can set the log_level causing the verifier logic > steps to be printed. I guess adding it to bpftool might be nice. At least > I would find it useful. I'll probably get to it sometime if its not > already there somewhere and/or someone doesn't beat me to it. +1 Was wondering whether it may be worth it moving parts of the logic from bpftool into libbpf wrt jit dump as a higher level api, so it could be used directly for checking out the jit disasm + opcodes for specific tests given we have the fd there as well, but that might be too specific perhaps and would bring one more lib dependency to libbpf for a rather narrow use case. Adding sleep before prog fd close and/or shelling out to bpftool etc all is a crude temporary hack as well (currently using something long these lines locally). Would it make sense to dump some meta data and generated opcodes per test case to a file as opt-in e.g. ./test_verifier 711 --dump produces 711.opcodes out of bpf_obj_get_info_by_fd() which then bpftool could dump this artifact through its own disasm? Thanks, Daniel