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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 EBAB4C43461 for ; Tue, 15 Sep 2020 21:04:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9DA8F20732 for ; Tue, 15 Sep 2020 21:04:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UnvU6HDe" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728073AbgIOVEI (ORCPT ); Tue, 15 Sep 2020 17:04:08 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:44613 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728053AbgIOVCj (ORCPT ); Tue, 15 Sep 2020 17:02:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600203758; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=7QHIRSjUq0tJFcI92B4kapSPBKJs2g6zBRXj5O6BhSQ=; b=UnvU6HDeHzuShn9qzo6D5NNGnQ/Zyn1JkFUzHkxVOL+NHzWF27VtYea2jZXIJcVNzGHnuq Q4GlgGcW8ueYwRC7GSSIy1sBD77WaJ8+fr0AfF7YjwJn1F+G0hu/sxV9I8h4bonSJ0v+S0 apXd/2YiMTaQxLqD3OyggAwKEhGdvT4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-518-Jt6zVwijMvOsIG08nd4cyg-1; Tue, 15 Sep 2020 17:02:36 -0400 X-MC-Unique: Jt6zVwijMvOsIG08nd4cyg-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5621B107465E; Tue, 15 Sep 2020 21:02:34 +0000 (UTC) Received: from treble (ovpn-112-136.rdu2.redhat.com [10.10.112.136]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 36F647EB97; Tue, 15 Sep 2020 21:02:33 +0000 (UTC) Date: Tue, 15 Sep 2020 16:02:31 -0500 From: Josh Poimboeuf To: Borislav Petkov Cc: Nick Desaulniers , Rong Chen , kernel test robot , "Li, Philip" , x86-ml , LKML , clang-built-linux , Marco Elver Subject: Re: [tip:x86/seves] BUILD SUCCESS WITH WARNING e6eb15c9ba3165698488ae5c34920eea20eaa38e Message-ID: <20200915210231.ysaibtkeibdm4zps@treble> References: <5f60c4e0.Ru0MTgSE9A7mqhpG%lkp@intel.com> <20200915135519.GJ14436@zn.tnic> <20200915141816.GC28738@shao2-debian> <20200915160554.GN14436@zn.tnic> <20200915170248.gcv54pvyckteyhk3@treble> <20200915204912.GA14436@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200915204912.GA14436@zn.tnic> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 15, 2020 at 10:49:12PM +0200, Borislav Petkov wrote: > On Tue, Sep 15, 2020 at 01:12:24PM -0700, Nick Desaulniers wrote: > > 1 warning: objtool: ist_exc_vmm_communication()+0x12: unreachable instruction > > That looks interesting. So your .o has: > > 00000000000004c0 : > 4c0: 55 push %rbp > 4c1: 48 89 e5 mov %rsp,%rbp > 4c4: 48 c7 c7 00 00 00 00 mov $0x0,%rdi > 4cb: 31 c0 xor %eax,%eax > 4cd: e8 00 00 00 00 callq 4d2 > 4d2: 0f 0b ud2 > 4d4: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1) > 4db: 00 00 00 00 > 4df: 90 nop If you disassemble with "objdump -dr" it shows the relocations: 00000000000004c0 : 4c0: 55 push %rbp 4c1: 48 89 e5 mov %rsp,%rbp 4c4: 48 c7 c7 00 00 00 00 mov $0x0,%rdi 4c7: R_X86_64_32S .rodata.str1.1+0x1ef 4cb: 31 c0 xor %eax,%eax 4cd: e8 00 00 00 00 callq 4d2 4ce: R_X86_64_PLT32 panic-0x4 4d2: 0f 0b ud2 4d4: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1) 4db: 00 00 00 00 4df: 90 nop panic() is noreturn, so the compiler is enforcing the fact that it doesn't return, by trapping if it does return. I seem to remember that's caused by CONFIG_UBSAN_TRAP. -- Josh