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=unavailable 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 6DD70C2B9F4 for ; Thu, 17 Jun 2021 20:41:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47436613E7 for ; Thu, 17 Jun 2021 20:41:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231553AbhFQUn3 (ORCPT ); Thu, 17 Jun 2021 16:43:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:35550 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230519AbhFQUn2 (ORCPT ); Thu, 17 Jun 2021 16:43:28 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5F2EF610A7; Thu, 17 Jun 2021 20:41:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1623962480; bh=2YUU2tY2xJoJ21hHHc5TWXB8wa+Kel08+1ETHXIJ6Ps=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LDKwc/AUQ4UZ3H3++Bdu3dSWEScRmpNeVbdycEVqbaQDDcB2hcG543XvAgQaQEYaY B08fcADjJhdv4CSTRqF8CN3KitSmGkxFlP/O1mthyN9R+iwaSYMCOm5g9nAAgX+GxK 9H83ROEa1ZDBkwOJRUQIadmiqDPjYlsij9wVxt9SKOQTgWuTJb2232imWc5jFQUDW6 +mhaaTh2dpAqrhZoRH82l28B7FvRfovIGQqXd0GS/knbSJ6AAppnWb/tR4n4bOvCf6 R1fGnimySS5loanhzwTFoE8O+VYL/MtmTm+rPSCtaP15BwRYPxHj41d1DeUR1ozl0e Ryj3pn2M1nTdg== Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id EAF7D40B1A; Thu, 17 Jun 2021 17:41:17 -0300 (-03) Date: Thu, 17 Jun 2021 17:41:17 -0300 From: Arnaldo Carvalho de Melo To: Andrii Nakryiko Cc: Arnaldo Carvalho de Melo , 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 Thu, Jun 17, 2021 at 01:03:17PM -0700, Andrii Nakryiko escreveu: > On Thu, Jun 17, 2021 at 12:53 PM Arnaldo Carvalho de Melo > wrote: > > > > Em Thu, Jun 17, 2021 at 11:48:47AM -0300, Arnaldo Carvalho de Melo escreveu: > > > 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... > > > > So I updated clang and now I'm stumbling on another one, again using > > pahole 1.21 + fixes, without any of my changes, is this a known issue? > > > > [root@seventh bpf]# pwd > > /mnt/linux/tools/testing/selftests/bpf > > [root@seventh bpf]# git log --oneline -5 > > 94f0b2d4a1d0 (HEAD -> master, torvalds/master) proc: only require mm_struct for writing > > Please use bpf-next tree. Bleeding edge clang started generating new > ELF relocation types, so you need bleeding edge libbpfs in selftests > to handle that during static linking. Yeah, bleeding edge indeed, will use that then > > a33d62662d27 afs: Fix an IS_ERR() vs NULL check > > 009c9aa5be65 (tag: v5.13-rc6) Linux 5.13-rc6 > > e4e453434a19 Merge tag 'perf-tools-fixes-for-v5.13-2021-06-13' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux > > 960f0716d80f Merge tag 'nfs-for-5.13-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs > > [root@seventh bpf]# > > [root@seventh bpf]# make run_tests > > I never use make run_tests. One more thing to put into my BTF development cheat sheet, thanks. I looked at git log tools/testing/selftests/bpf and looked for the first commit, which I thought would have instructions on how to use it, and there I found about 'make run_tests'. > Try `make clean && make -j60 && sudo ./test_progs`. > > > > > GEN-SKEL [test_progs] atomic_bounds.skel.h > > GEN-SKEL [test_progs] atomics.skel.h > > GEN-SKEL [test_progs] bind4_prog.skel.h > > libbpf: elf: skipping unrecognized data section(6) .rodata.str1.1 > > GEN-SKEL [test_progs] bind6_prog.skel.h > > libbpf: elf: skipping unrecognized data section(6) .rodata.str1.1 > > GEN-SKEL [test_progs] bind_perm.skel.h > > GEN-SKEL [test_progs] bpf_cubic.skel.h > > libbpf: ELF relo #0 in section #15 has unexpected type 2 in /mnt/linux/tools/testing/selftests/bpf/bpf_cubic.o > > Error: failed to link '/mnt/linux/tools/testing/selftests/bpf/bpf_cubic.o': Unknown error -22 (-22) > > make: *** [Makefile:456: /mnt/linux/tools/testing/selftests/bpf/bpf_cubic.skel.h] Error 234 > > [root@seventh bpf]# clang -v |& head -2 > > clang version 13.0.0 (https://github.com/llvm/llvm-project dee2c76b4c46e71903e3d86ab7555a80d51d1288) > > Target: x86_64-unknown-linux-gnu > > [root@seventh bpf]# > > > > - Arnaldo > > > > > 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