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=-6.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 32028C04A6B for ; Thu, 9 May 2019 01:37:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C954214AF for ; Thu, 9 May 2019 01:37:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726594AbfEIBhD (ORCPT ); Wed, 8 May 2019 21:37:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36540 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725778AbfEIBhB (ORCPT ); Wed, 8 May 2019 21:37:01 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 626E9307D935; Thu, 9 May 2019 01:37:01 +0000 (UTC) Received: from MiWiFi-R3L-srv.redhat.com (ovpn-12-17.pek2.redhat.com [10.72.12.17]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6DB1F19744; Thu, 9 May 2019 01:36:58 +0000 (UTC) From: Baoquan He To: linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, mingo@kernel.org, bp@alien8.de, hpa@zytor.com, kirill.shutemov@linux.intel.com, x86@kernel.org, dyoung@redhat.com, Baoquan He Subject: [PATCH v4 2/3] x86/kexec/64: Error out if try to jump to old 4-level kernel from 5-level kernel Date: Thu, 9 May 2019 09:36:43 +0800 Message-Id: <20190509013644.1246-3-bhe@redhat.com> In-Reply-To: <20190509013644.1246-1-bhe@redhat.com> References: <20190509013644.1246-1-bhe@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Thu, 09 May 2019 01:37:01 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the running kernel has 5-level paging activated, the 5-level paging mode is preserved across kexec. If the kexec'ed kernel does not contain support for handling active 5-level paging mode in the decompressor, the decompressor will crash with #GP. Prevent this situation at load time. If 5-level paging is active, check the xloadflags whether the kexec kernel can handle 5-level paging at least in the decompressor. If not, reject the load attempt and print out error message. Signed-off-by: Baoquan He Acked-by: Kirill A. Shutemov --- arch/x86/kernel/kexec-bzimage64.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c index 22f60dd26460..858cc892672f 100644 --- a/arch/x86/kernel/kexec-bzimage64.c +++ b/arch/x86/kernel/kexec-bzimage64.c @@ -321,6 +321,11 @@ static int bzImage64_probe(const char *buf, unsigned long len) return ret; } + if (!(header->xloadflags & XLF_5LEVEL) && pgtable_l5_enabled()) { + pr_err("Can not jump to old 4-level kernel from 5-level kernel.\n"); + return ret; + } + /* I've got a bzImage */ pr_debug("It's a relocatable bzImage64\n"); ret = 0; -- 2.17.2