From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752394AbcAESvJ (ORCPT ); Tue, 5 Jan 2016 13:51:09 -0500 Received: from www.sr71.net ([198.145.64.142]:53874 "EHLO blackbird.sr71.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751456AbcAESvG (ORCPT ); Tue, 5 Jan 2016 13:51:06 -0500 Subject: Re: [PATCH 1/5] x86: fix early command-line parsing when matching at end To: Borislav Petkov References: <20151222225237.08CDE5F1@viggo.jf.intel.com> <20151222225238.9AEB560C@viggo.jf.intel.com> <20160105183542.GD4617@pd.tnic> Cc: x86@kernel.org, linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com, hpa@zytor.com, fenghua.yu@intel.com, yu-cheng.yu@intel.com From: Dave Hansen Message-ID: <568C1099.5000100@sr71.net> Date: Tue, 5 Jan 2016 10:51:05 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: <20160105183542.GD4617@pd.tnic> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/05/2016 10:35 AM, Borislav Petkov wrote: > On Tue, Dec 22, 2015 at 02:52:38PM -0800, Dave Hansen wrote: >> From: Dave Hansen >> The x86 early command line parsing in cmdline_find_option_bool() >> is buggy. If it matches a specified 'option' all the way to >> the end of the command-line, it will consider it a match. >> >> For instance, >> >> cmdline = "foo"; >> cmdline_find_option_bool(cmdline, "fool"); >> >> will return 1. This is particularly annoying since we have >> actual FPU options like "noxsave" and "noxsaves" So, >> command-line "foo bar noxsave" will match *BOTH* a "noxsave" and >> "noxsaves". (This turns out not to be an actual problem because >> "noxsave" implies "noxsaves", but it's still confusing.) > > So I booted a guest with this command line: > > [ 0.000000] Kernel command line: root=/dev/sda1 resume=/dev/sdb1 debug ignore_loglevel log_buf_len=16M earlyprintk=ttyS0,115200 console=ttyS0,115200 console=tty0 noxsave > > after applying the debug hunk below. However, the only debug output I > got is this: > > [ 0.000000] x86_noxsave_setup > > If I supply "noxsaves", I get, as expected > > [ 0.000000] x86_noxsaves_setup > > only. Ditto for "noxsaveopt". > > So what am I missing? The current code uses __setup() which uses different parsing than cmdline_find_option_bool(). We're going to have to move the noxsave* ones over to cmdline_find_option_bool() since we need the parsing earlier than __setup() works. The changelog should have been more clear on this, though.