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=-5.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 16214C56201 for ; Wed, 21 Oct 2020 05:52:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 92CB720770 for ; Wed, 21 Oct 2020 05:52:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603259544; bh=FQuYS5uKq+i9aKct0MNZwBQsnDQ6/7v175jGjlBHi4U=; h=Subject:To:Cc:References:From:Date:In-Reply-To:List-ID:From; b=knFsSAXsMahNfyMcONRpH6Bs9LwiyNhFdskKCFWpZmSxR3MJi1G9b2AXYUivkLyT1 06WnR/VnNEIdSbvcxjv2v/qp6+TiXbM61NptrGsJEH2Xtc5PRFqgpsXP1J1aNJAwb7 q5XgIbmaR0AvY0E1xkswxSews62WiWcENfE9KZXg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393731AbgJUFwY (ORCPT ); Wed, 21 Oct 2020 01:52:24 -0400 Received: from mail-ej1-f66.google.com ([209.85.218.66]:38249 "EHLO mail-ej1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2393570AbgJUFwX (ORCPT ); Wed, 21 Oct 2020 01:52:23 -0400 Received: by mail-ej1-f66.google.com with SMTP id ce10so1322479ejc.5; Tue, 20 Oct 2020 22:52:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Ql0foaRbL3lg/b/jhl8Q1apB2P43TnsO4Qk8XcA0+CQ=; b=okv9a+fzDSFgfKjoaQoLTHlSzKOnH99MRsX8+5Eh7ygBjkZImRLfwU7qtV8UkCj3dd fZYOYW8kI9VAdN3rXcCt+jy6dk90zxqzm2isy4GzjrN8ApuBBf3elhz/z5ywrT+z72PH r0LYc3JHtBlwvWWWd/PM0CCHR7YWwpXhtARIyJPFzRV64DU6hVAY29PIa9MJurqIC3Rz CI0HIVWlstUDFrxr9mR5jx/8ppPB7smB9Xnh8jMGY2dyxJh+W2tZBZpj4b56ZTpIpwHA tIsxL+yRvmjkUezwtg6edz52q1u0MtzYdtVGjA4KeKMbo747Lw2JYJL6/Wag9ffjRw0o d+Hg== X-Gm-Message-State: AOAM533L6FLH0qpUk4ESLEHbybG7vMQsPgjk5AjvKQm148eV73aH+0k8 RpEenhyfLOPGCZfc6iy6Rys= X-Google-Smtp-Source: ABdhPJwqxJd22hZw5ifdcuRjQCbw+SS2XKSqRwmRnYpwYb3cFVhSVe+qZqAamH5/lDJCjnJyeYvgFg== X-Received: by 2002:a17:906:234d:: with SMTP id m13mr1820133eja.497.1603259541936; Tue, 20 Oct 2020 22:52:21 -0700 (PDT) Received: from ?IPv6:2a0b:e7c0:0:107::70f? ([2a0b:e7c0:0:107::70f]) by smtp.gmail.com with ESMTPSA id l12sm1023074edj.75.2020.10.20.22.52.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 Oct 2020 22:52:20 -0700 (PDT) Subject: Re: Segfault in pahole 1.18 when building kernel 5.9.1 for arm64 To: Andrii Nakryiko Cc: =?UTF-8?Q?=c3=89rico_Rolim?= , dwarves@vger.kernel.org, open list , Arnaldo Carvalho de Melo , Hao Luo References: <82b757bb-1f49-ab02-2f4b-89577d56fec9@kernel.org> From: Jiri Slaby Message-ID: Date: Wed, 21 Oct 2020 07:52:19 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: dwarves@vger.kernel.org On 20. 10. 20, 19:15, Andrii Nakryiko wrote: > On Tue, Oct 20, 2020 at 3:51 AM Jiri Slaby wrote: >> >> 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;; > > What's readelf's output for that symbol? If it's legal for SST_OBJECT > to have size zero, then we should just skip those in pahole. But it > shouldn't crash in either case, of course. But as Arnaldo mentioned, > that code changed significantly recently, so please check with latest > pahole from tmp.libbtf_encoder branch. ... >> Yeah, I observe the very same. I reported it at: >> https://bugzilla.suse.com/show_bug.cgi?id=1177921 If you looked here, you would see: > $ readelf -Ws vml |grep arm64_ssbd_callback_re > 154271: ffff80001133e000 0 OBJECT GLOBAL DEFAULT 22 __kvm_nvhe_arm64_ssbd_callback_required > 159609: ffff80001133e000 8 OBJECT WEAK DEFAULT 22 arm64_ssbd_callback_required Yes, its zero-sized. And yes, the error happens even with tmp.libbtf_encoder, but pahole doesn't crash and the build finishes fine. thanks, -- js