From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id AFE4C7D082 for ; Sat, 6 Oct 2018 08:43:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727799AbeJFPqE (ORCPT ); Sat, 6 Oct 2018 11:46:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49758 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727228AbeJFPqE (ORCPT ); Sat, 6 Oct 2018 11:46:04 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id BBB2C30014C6; Sat, 6 Oct 2018 08:43:37 +0000 (UTC) Received: from MiWiFi-R3L-srv.redhat.com (ovpn-8-16.pek2.redhat.com [10.72.8.16]) by smtp.corp.redhat.com (Postfix) with ESMTP id C2334608F2; Sat, 6 Oct 2018 08:43:33 +0000 (UTC) From: Baoquan He To: mingo@kernel.org Cc: linux-kernel@vger.kernel.org, x86@kernel.org, linux-doc@vger.kernel.org, tglx@linutronix.de, thgarnie@google.com, corbet@lwn.net, Baoquan He Subject: [PATCH 1/3] x86/KASLR: Update KERNEL_IMAGE_SIZE description Date: Sat, 6 Oct 2018 16:43:25 +0800 Message-Id: <20181006084327.27467-2-bhe@redhat.com> In-Reply-To: <20181006084327.27467-1-bhe@redhat.com> References: <20181006084327.27467-1-bhe@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Sat, 06 Oct 2018 08:43:37 +0000 (UTC) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Currently CONFIG_RANDOMIZE_BASE=y is set by default, which makes some of the old comments above the KERNEL_IMAGE_SIZE definition out of date. Update them to the current state of affairs. Signed-off-by: Baoquan He --- arch/x86/include/asm/page_64_types.h | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h index 6afac386a434..cd0cf1c568b4 100644 --- a/arch/x86/include/asm/page_64_types.h +++ b/arch/x86/include/asm/page_64_types.h @@ -59,13 +59,16 @@ #endif /* - * Kernel image size is limited to 1GiB due to the fixmap living in the - * next 1GiB (see level2_kernel_pgt in arch/x86/kernel/head_64.S). Use - * 512MiB by default, leaving 1.5GiB for modules once the page tables - * are fully set up. If kernel ASLR is configured, it can extend the - * kernel page table mapping, reducing the size of the modules area. + * Maximum kernel image size is limited to 1 GiB, due to the fixmap living + * in the next 1 GiB (see level2_kernel_pgt in arch/x86/kernel/head_64.S). + * + * On KASLR use 1 GiB by default, leaving 1 GiB for modules once the + * page tables are fully set up. + * + * If KASLR is disabled we can shrink it to 0.5 GiB and increase the size + * of the modules area to 1.5 GiB. */ -#if defined(CONFIG_RANDOMIZE_BASE) +#ifdef CONFIG_RANDOMIZE_BASE #define KERNEL_IMAGE_SIZE (1024 * 1024 * 1024) #else #define KERNEL_IMAGE_SIZE (512 * 1024 * 1024) -- 2.13.6