Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753255AbcDOIKP (ORCPT ); Fri, 15 Apr 2016 04:10:15 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:35041 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753079AbcDOIKC (ORCPT ); Fri, 15 Apr 2016 04:10:02 -0400 Date: Fri, 15 Apr 2016 10:09:56 +0200 From: Ingo Molnar To: Kees Cook Cc: Yinghai Lu , Baoquan He , Ard Biesheuvel , Matt Redfearn , x86@kernel.org, "H. Peter Anvin" , Ingo Molnar , Borislav Petkov , Vivek Goyal , Andy Lutomirski , lasse.collin@tukaani.org, Andrew Morton , Dave Young , kernel-hardening@lists.openwall.com, LKML Subject: Re: [PATCH v5 04/21] x86, boot: Move compressed kernel to end of decompression buffer Message-ID: <20160415080956.GE30715@gmail.com> References: <1460672954-32567-1-git-send-email-keescook@chromium.org> <1460672954-32567-5-git-send-email-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1460672954-32567-5-git-send-email-keescook@chromium.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1282 Lines: 39 * Kees Cook wrote: > From: Yinghai Lu > > This change makes later calculations about where the kernel is located > easier to reason about. To better understand this change, we must first > clarify what VO and ZO are. They were introduced in commits by hpa: > > 77d1a49 x86, boot: make symbols from the main vmlinux available > 37ba7ab x86, boot: make kernel_alignment adjustable; new bzImage fields > > Specifically: > > VO: > - uncompressed kernel image > - size: VO__end - VO__text ("VO_INIT_SIZE" define) > > ZO: > - bootable compressed kernel image (boot/compressed/vmlinux) > - head text + compressed kernel (VO and relocs table) + decompressor code > - size: ZO__end - ZO_startup_32 ("ZO_INIT_SIZE" define, though see below) > > The INIT_SIZE definition is used to find the larger of the two image sizes: > > #define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_extract_offset) > #define VO_INIT_SIZE (VO__end - VO__text) > #if ZO_INIT_SIZE > VO_INIT_SIZE > #define INIT_SIZE ZO_INIT_SIZE > #else > #define INIT_SIZE VO_INIT_SIZE > #endif Please also harmonize all the prefixes, i.e. use VO__/ZO__ everywhere (rename things where necessary), instead of this mixed up VO_/ZO_/VO__/ZO__ mess. Thanks, Ingo