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=-9.1 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,URIBL_BLOCKED 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 4B4B2C433E7 for ; Tue, 20 Oct 2020 12:20:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D479822265 for ; Tue, 20 Oct 2020 12:20:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603196418; bh=EnGv0MFvniAMktEmBQLAQeOA6GSZykQGPJQwZFpJbu8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=MuiZoi+6u3BxbUe1InBLwac0QTIO8p1Tf/3CAqFb4K/NhyCZlLLB6Y+VAfqRJaH4h +WlF3R4tWeqFxElqiqtXBOPM4+NVPQyBhMJHf7jxL9wIf1dDxoYehAdMXWvCYjG8nP Pjp0pu27ycTPxdPVtqGJ/6gIHyxLX88hgm2ANYSM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2394370AbgJTMUS (ORCPT ); Tue, 20 Oct 2020 08:20:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:40650 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2394088AbgJTMUS (ORCPT ); Tue, 20 Oct 2020 08:20:18 -0400 Received: from quaco.ghostprotocols.net (unknown [179.97.37.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 14EFC2222F; Tue, 20 Oct 2020 12:20:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603196417; bh=EnGv0MFvniAMktEmBQLAQeOA6GSZykQGPJQwZFpJbu8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KoWFD7p4h8oNaarWyr54GOzPn0sRHLXL4qeLKbMOhKk92dmULKQJ62kcKfrVUl1MS a2ucocpuJ9xe80bHEVDA5yrebxuBn4gY5kMkk5BmKhTBKYxwLGZi4jjGPFppEBveaH 9oi0olveij9UJn7adyi1F70MAfloNGyUhhboIR1c= Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 27D9B403C2; Tue, 20 Oct 2020 09:20:15 -0300 (-03) Date: Tue, 20 Oct 2020 09:20:15 -0300 From: Arnaldo Carvalho de Melo To: Jiri Slaby Cc: =?iso-8859-1?Q?=C9rico?= Rolim , dwarves@vger.kernel.org, linux-kernel@vger.kernel.org, Arnaldo Carvalho de Melo , Hao Luo , Andrii Nakryiko Subject: Re: Segfault in pahole 1.18 when building kernel 5.9.1 for arm64 Message-ID: <20201020122015.GH2294271@kernel.org> References: <82b757bb-1f49-ab02-2f4b-89577d56fec9@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <82b757bb-1f49-ab02-2f4b-89577d56fec9@kernel.org> X-Url: http://acmel.wordpress.com Precedence: bulk List-ID: X-Mailing-List: dwarves@vger.kernel.org Em Tue, Oct 20, 2020 at 11:01:39AM +0200, Jiri Slaby escreveu: > Hi, > > On 19. 10. 20, 1:18, Érico Rolim wrote: > > I'm trying to build kernel 5.9.1 for arm64, and my dotconfig has > > `CONFIG_DEBUG_INFO_BTF=y`, which requires pahole for building. However, pahole > > version 1.18 segfaults during the build, as can be seen below: > > > > PAHOLE: Error: Found symbol of zero size when encoding btf (sym: > > '__kvm_nvhe_arm64_ssbd_callback_required', cu: > > 'arch/arm64/kernel/cpu_errata.c'). > > The symbol is an alias coming from arch/arm64/kernel/vmlinux.lds: > __kvm_nvhe_arm64_ssbd_callback_required = arm64_ssbd_callback_required;; > > > PAHOLE: Error: Use '-j' or '--force' to ignore such symbols and force > > emit the btf. > > scripts/link-vmlinux.sh: line 141: 43837 Segmentation fault > > LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1} > > LD .tmp_vmlinux.kallsyms1 > > KSYM .tmp_vmlinux.kallsyms1.o > > LD .tmp_vmlinux.kallsyms2 > > KSYM .tmp_vmlinux.kallsyms2.o > > LD vmlinux > > BTFIDS vmlinux > > FAILED: load BTF from vmlinux: Unknown error -2make: *** > > [Makefile:1162: vmlinux] Error 255 > > > > It is possible to force the build to continue if > > > > LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1} > > > > in scripts/link-vmlinux.sh is changed to > > > > LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J --btf_encode_force ${1} > > > > The suggested `-j` or `--force` flags don't exist, since they were removed in > > [1]. I believe `--btf_encode_force` should be suggested instead. > > Agreed, '--btf_encode_force' makes pahole to proceed without crashes. > > > It should be noted that the same build, but with pahole version 1.17, works > > without issue, so I think this is either a regression in pahole or the script > > will need to be changed for newer versions of pahole. > > Yeah, I observe the very same. I reported it at: > https://bugzilla.suse.com/show_bug.cgi?id=1177921 Would it be possible to try with https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?h=tmp.libbtf_encoder ? This switches to using libbpf for the BTF encoder and may have fixed this problem. - Arnaldo > The backtrace: > > (gdb) where > > #0 __memmove_sse2_unaligned_erms () at > ../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:300 > > #1 0x00007ffff7f78346 in memcpy (__len=, __src= out>, __dest=, __dest=, __src=, > __len=) at /usr/include/bits/string_fortified.h:34 > > #2 gobuffer__add (gb=0x555555569aa0, s=0x7fffffffb50c, len=12) at > /usr/src/debug/dwarves-1.18-1.1.x86_64/gobuffer.c:87 > > #3 0x00007ffff7f8671f in btf_elf__add_datasec_type > (btfe=btfe@entry=0x555555569a40, > section_name=section_name@entry=0x7ffff7fa43ad ".data..percpu", > var_secinfo_buf=var_secinfo_buf@entry=0x555555569ac0) at > /usr/src/debug/dwarves-1.18-1.1.x86_64/libbtf.c:721 > > #4 0x00007ffff7f8d766 in btf_elf__encode (flags=0 '\000', > btfe=0x555555569a40) at /usr/src/debug/dwarves-1.18-1.1.x86_64/libbtf.c:857 > > #5 btf_elf__encode (btfe=0x555555569a40, flags=) at > /usr/src/debug/dwarves-1.18-1.1.x86_64/libbtf.h:71 > > #6 0x00007ffff7f7fc70 in btf_encoder__encode () at > /usr/src/debug/dwarves-1.18-1.1.x86_64/btf_encoder.c:213 > > #7 0x00007ffff7f80d17 in cu__encode_btf (cu=0x55555638d9b0, verbose=0, > force=false, skip_encoding_vars=false) at > /usr/src/debug/dwarves-1.18-1.1.x86_64/btf_encoder.c:255 > > #8 0x000055555555ac4d in pahole_stealer (cu=0x55555638d9b0, > conf_load=) at > /usr/src/debug/dwarves-1.18-1.1.x86_64/pahole.c:2366 > > #9 0x00007ffff7f89dab in finalize_cu (cus=0x5555555622d0, > dcu=0x7fffffffd080, conf=0x5555555610e0 , cu=0x55555638d9b0) at > /usr/src/debug/dwarves-1.18-1.1.x86_64/dwarf_loader.c:2473 > > #10 finalize_cu_immediately (conf=0x5555555610e0 , > dcu=0x7fffffffd080, cu=0x55555638d9b0, cus=0x5555555622d0) at > /usr/src/debug/dwarves-1.18-1.1.x86_64/dwarf_loader.c:2317 > > #11 cus__load_module (cus=cus@entry=0x5555555622d0, conf=0x5555555610e0 > , mod=mod@entry=0x555555564760, dw=0x555555565960, > elf=elf@entry=0x555555562360, filename=0x7fffffffe846 "ss") at > /usr/src/debug/dwarves-1.18-1.1.x86_64/dwarf_loader.c:2473 > > #12 0x00007ffff7f8a0f1 in cus__process_dwflmod (dwflmod=0x555555564760, > userdata=, name=, base=, > arg=0x7fffffffe1b0) at > /usr/src/debug/dwarves-1.18-1.1.x86_64/dwarf_loader.c:2518 > > #13 0x00007ffff7d4f571 in dwfl_getmodules () from /usr/lib64/libdw.so.1 > > #14 0x00007ffff7f823ed in cus__process_file (filename=0x7fffffffe846 "ss", > fd=3, conf=, cus=0x5555555622d0) at > /usr/src/debug/dwarves-1.18-1.1.x86_64/dwarf_loader.c:2571 > > #15 dwarf__load_file (cus=0x5555555622d0, conf=, > filename=0x7fffffffe846 "ss") at > /usr/src/debug/dwarves-1.18-1.1.x86_64/dwarf_loader.c:2588 > > #16 0x00007ffff7f76771 in cus__load_file (cus=cus@entry=0x5555555622d0, > conf=conf@entry=0x5555555610e0 , filename=0x7fffffffe846 "ss") at > /usr/src/debug/dwarves-1.18-1.1.x86_64/dwarves.c:1958 > > #17 0x00007ffff7f798a8 in cus__load_files (cus=0x5555555622d0, > conf=0x5555555610e0 , filenames=0x7fffffffe518) at > /usr/src/debug/dwarves-1.18-1.1.x86_64/dwarves.c:2316 > > #18 0x00005555555576fc in main (argc=3, argv=0x7fffffffe508) at > /usr/src/debug/dwarves-1.18-1.1.x86_64/pahole.c:2687 > > > I suspect: > commit f3d9054ba8ff1df0fc44e507e3a01c0964cabd42 > Author: Hao Luo > AuthorDate: Wed Jul 8 13:44:10 2020 -0700 > > btf_encoder: Teach pahole to store percpu variables in vmlinux BTF. > > > Which added this machinery (btf_elf__add_datasec_type in particular). > > > - [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/pahole.c?h=v1.18&id=1abc001417b579b86a9b27ff88c9095d8f498a46 > > > > Thanks, > > Érico > > > > > -- > js > suse labs -- - Arnaldo