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=-11.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS 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 686F8C2B9F4 for ; Thu, 17 Jun 2021 14:48:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 444F5613CA for ; Thu, 17 Jun 2021 14:48:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231854AbhFQOu7 (ORCPT ); Thu, 17 Jun 2021 10:50:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:54960 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231759AbhFQOu6 (ORCPT ); Thu, 17 Jun 2021 10:50:58 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B7BED613E9; Thu, 17 Jun 2021 14:48:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1623941330; bh=diSD2DV+ZMSbg7QBx9qRA4lRHgK0oR6VJQGUEUYjj4A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=opkK5Rty+mv8NbdpPEsQjyN1t2JTj02HtkNefuZ+uC7DScdpkGrr5n/rpVvBj4A6J 7ms+c9cBkuL/gkovXTfd4q32/TIWyLrXi74Kni3OiJcgWybEgut/QS74Kupa3QUjfU WnbesIrb7O3zuhJKssszI2bJzb4BrGQN5di3JBxTe3M3jsNJOQ4M9u9fXyAOEbDML3 Nv+OVALG83VMOIOy2nHXwQamP7oE0326KB0XGcQu71SBf+RIShcxfuhQBEUEHp1IVz M43v4ofF8KRvLsXEM+7/WMThsAVvqxmSJlTyNjsrPhaiEIW2IXdzZ+kXfgtwkyy2ue e4GthMF48EH/A== Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id DDE7140B1A; Thu, 17 Jun 2021 11:48:47 -0300 (-03) Date: Thu, 17 Jun 2021 11:48:47 -0300 From: Arnaldo Carvalho de Melo To: Andrii Nakryiko Cc: Yonghong Song , bpf , dwarves@vger.kernel.org, siudin@fb.com Subject: Re: latest pahole breaks libbpf CI and let's talk about staging Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Url: http://acmel.wordpress.com Precedence: bulk List-ID: X-Mailing-List: dwarves@vger.kernel.org Em Wed, Jun 16, 2021 at 03:36:54PM -0700, Andrii Nakryiko escreveu: > On Wed, Jun 16, 2021 at 1:41 PM Arnaldo Carvalho de Melo wrote: > > And if I use pahole's BTF loader I find the info about that function: > > > > [acme@seventh linux]$ strace -e openat -o /tmp/bla pfunct -F btf tcp_cong_avoid_ai ; grep vmlinux /tmp/bla > > void tcp_cong_avoid_ai(struct tcp_sock * tp, u32 w, u32 acked); > > openat(AT_FDCWD, "/sys/kernel/btf/vmlinux", O_RDONLY) = 3 > > > > So this should be unrelated to the breakage you noticed in the CI. > > > > I'm trying to to reproduce the CI breakage by building the kernel and > > running selftests after a reboot. > > > > I suspect I'm missing something, can you see what it is? > > Oh, I didn't realize initially what it is. This is not kernel-related, > you are right. You just need newer Clang. Can you please use nightly > version or build from sources? Basically, your Clang is too old and it > doesn't generate BTF information for extern functions in BPF code. Oh well, I thought that that clang was new enough, the system being Fedora rawhide: [acme@seventh ~]$ clang -v |& head -1 clang version 12.0.0 (https://github.com/llvm/llvm-project 87369c626114ae17f4c637635c119e6de0856a9a) I'm now building the single-repo main... Would you consider a patch for libbpf that would turn this: > > > libbpf: failed to find BTF for extern 'tcp_cong_avoid_ai' [27] section: -2 > > > Error: failed to open BPF object file: No such file or directory > > > make: *** [Makefile:460: /mnt/linux/tools/testing/selftests/bpf/bpf_cubic.skel.h] Error 255 > > > make: *** Deleting file '/mnt/linux/tools/testing/selftests/bpf/bpf_cubic.skel.h' > > > make: Leaving directory '/mnt/linux/tools/testing/selftests/bpf' Into: libbpf: failed to find BTF for extern 'tcp_cong_avoid_ai' [27] section: -2 HINT: Please update your clang/llvm toolchain to at least cset abcdef123456 HINT: That is where clang started generating BTF information for extern functions in BPF code. ? :-) - Arnaldo