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=-7.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham 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 21642C4360F for ; Wed, 3 Apr 2019 12:05:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC66C20830 for ; Wed, 3 Apr 2019 12:05:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725990AbfDCMFL (ORCPT ); Wed, 3 Apr 2019 08:05:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43916 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725941AbfDCMFL (ORCPT ); Wed, 3 Apr 2019 08:05:11 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8239618DF7C; Wed, 3 Apr 2019 12:05:10 +0000 (UTC) Received: from sandy.ghostprotocols.net (ovpn-112-16.phx2.redhat.com [10.3.112.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 824EE64032; Wed, 3 Apr 2019 12:05:09 +0000 (UTC) Received: by sandy.ghostprotocols.net (Postfix, from userid 1000) id C2324628D; Wed, 3 Apr 2019 09:05:06 -0300 (BRT) Date: Wed, 3 Apr 2019 09:05:06 -0300 From: Arnaldo Carvalho de Melo To: Jiri Olsa Cc: Daniel Borkmann , andrii.nakryiko@gmail.com, bpf@vger.kernel.org, netdev@vger.kernel.org, kernel-team@fb.com, Andrii Nakryiko , Masahiro Yamada , Alexei Starovoitov , Yonghong Song , Martin KaFai Lau Subject: Re: [PATCH bpf-next] kbuild: add ability to generate BTF type info for vmlinux Message-ID: <20190403120506.GK2219@redhat.com> References: <20190402164950.429597-1-andrii.nakryiko@gmail.com> <20190403084619.GA23855@krava> <611b4f67-801e-1bab-7a43-a16d341187ba@iogearbox.net> <20190403091258.GA24875@krava> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190403091258.GA24875@krava> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.20 (2009-12-10) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Wed, 03 Apr 2019 12:05:10 +0000 (UTC) Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Em Wed, Apr 03, 2019 at 11:12:58AM +0200, Jiri Olsa escreveu: > On Wed, Apr 03, 2019 at 11:04:28AM +0200, Daniel Borkmann wrote: > > On 04/03/2019 10:46 AM, Jiri Olsa wrote: > > > On Tue, Apr 02, 2019 at 09:49:50AM -0700, andrii.nakryiko@gmail.com wrote: > > >> From: Andrii Nakryiko > > >> > > >> 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. > > > > > > hi, > > > I'm using the latest pahole from git tree: > > > https://github.com/acmel/dwarves.git > > > > > > and getting pahole crash: > > > > > > LD vmlinux > > > BTF vmlinux > > > die__process_inline_expansion: DW_TAG_label (0xa) @ <0x3eef8> not handled! > > > scripts/link-vmlinux.sh: line 96: 31222 Segmentation fault (core dumped) LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1} > > > make[1]: *** [/home/jolsa/linux/Makefile:1025: vmlinux] Error 139 > > > make: *** [Makefile:170: sub-make] Error 2 > > > > > > is there some other source/dependency I'm missing? > > > > Yesterday night, I've tested with [0] but seems to have the same HEAD as > > the github repo you pointed out. Seems the above is coming from pahole's > > __die__process_tag() bailing out with default for DW_TAG_label? > > > > On my side worked fine: > > hum, I also had to change the version of pahole in the patch to allow > version v1.12, because both latest pahole sources are on version 1.12, > did u have to do that? looks like there's v1.13 somewhere ;-) I'll get the --reorganize algorithm simplified to cope with some internal changes needed for the BTF encoding/decoding and tag v1.13 later today, max late this week. Then I'll go back adding the bitfield reorganization bits that will take a bit more work. Hopefully this way we get something to work with the Kbuild changes and have progress in that front. I'll look at the DW_TAG_label case too, please send me me in PVT the vmlinux file with that problem so that I can analyse it. > jirka > > SNIP > > > > > [0] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/