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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 64449C6778F for ; Wed, 25 Jul 2018 17:26:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2745820852 for ; Wed, 25 Jul 2018 17:26:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2745820852 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=real-time-systems.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730048AbeGYSjM convert rfc822-to-8bit (ORCPT ); Wed, 25 Jul 2018 14:39:12 -0400 Received: from mout.kundenserver.de ([212.227.17.10]:47637 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729027AbeGYSjM (ORCPT ); Wed, 25 Jul 2018 14:39:12 -0400 Received: from pc00012.rts.com ([46.237.192.139]) by mrelayeu.kundenserver.de (mreue103 [212.227.15.183]) with ESMTPSA (Nemesis) id 0LrHzA-1g7aQX3joq-0133S3; Wed, 25 Jul 2018 19:26:01 +0200 From: Dmitry Malkin Subject: Re: 4.17.x won't boot due to "x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G" Organization: Real-Time Systems GmbH To: linux-x86_64@vger.kernel.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , x86@kernel.org Message-ID: Date: Wed, 25 Jul 2018 19:26:02 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8BIT Content-Language: en-US X-Provags-ID: V03:K1:WjFqAAkRElC2ViqxZ+aWlnCt1/V/i1uyqw0C11PFTwCK8x8MYAM RdJ0RCgMFpfjrrkATs5z7ysw2gvohep6rMIeUeLx2G3SFugJifgS405Kgs4VkIZ06nV8OMu ODX05isLBBbknoe4GTVFBsSdpSdqkUbBThGXPGhFrF8hEEmzIoQAxuXfA1AAaQ8aNeqssgH bT4C7u1kjDi04IfyFDW8A== X-UI-Out-Filterresults: notjunk:1;V01:K0:ZS+7xzNjMqw=:4BfnJbiQvmZghW1EQPeeL6 xmJ1dYsK5MonGYULcxSX9hJpK6Ag7I3BxR+tfsYYr7L8ho5d1xRx+Ld6+odKqRs8LEKRfhfrQ 4gQ9J01T5/BqQZXQWZ+xr8YzOYnuvuKP5y4wEQKSUC4LzTDiTOETXTXcwhDleXXHFlHWkaLv8 /64suo64sxH3VEkbxL3jLLKvRnf1XIBg47fzSXxzHW1ci7/POL4yW/9Pku/oudxtxfeR01EAt I9y7lDcgL5lEhsoTQKF4Gj7SkcsCKZd7csJfbsNCOz33DSvRoNXgHQ5mzZsY1W7CgtMi03zk+ qMRbKMHRiwapQ3Yl+NuCtr7jbUjlM+ZV5UGunXeZIwiOm17lAIcfsxDwpRdQ59P96sVWYQ/tm kfPGaDYDf2JachxpMarhuE+sovBYnKiKJwAuWk/lYRvZw0eGZ3Z2vfQgVaAIG8K6nzykW/Cs+ /FpQqegN1KTurNPm102XPFGavBayXK6eNVwnz8DdKMBjXNqQmpR+j66GSlj20RgArTbO08VC8 dn9F0ibQMBPizLnUHrn0oXa5p1BS+GOxXdQQHjCGcwpImIS6oPHN3HyvwwbZ1D0HtosigMSoa 9iAKNJwWeHTCP8TYyGuFHlDkbLyC+RQ2UID7sUiKHpwZKIcDWS2j0iqUSL8LsxDevM8hTwnKA UP+uCiPerH7dQYDMYBOnMAw9tPysw43Cw7XFab21UKLrbRnjt8LTvlxam6xRev68nmEr0PbVv C7+FKSw5F3R2kP7U Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org there may be some other reasons which may cause undefined behavior (reboot for example): in arch/x86/boot/compressed/pgtable_64.c in function paging_prepare(): 1. structure "paging_config" allocated on stack without setting default value for flag "l5_required": >>struct paging_config paging_config = {}; l5_required is set only if CONFIG_X86_5LEVEL is defined 2. reading from memory which may be reserved in case of EFI systems: >>    ebda_start = *(unsigned short *)0x40e << 4; >>    bios_start = *(unsigned short *)0x413 << 10; Also, on EFI system without CSM it will results in all zeros. Which will place trampoline_start to 0x9d000. And it also may be reserved memory. In fact I have such system and it is causes instant reboot (when code starts copying to "trampoline_start"). 3. paging_prepare(void) returns "struct paging_config". Copy by value. Is it really specified by ABI or GCC itself that the second field (which is flag "l5_required") will go to RDX register?