From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755892Ab0BOSHc (ORCPT ); Mon, 15 Feb 2010 13:07:32 -0500 Received: from terminus.zytor.com ([198.137.202.10]:42395 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755773Ab0BOSHb (ORCPT ); Mon, 15 Feb 2010 13:07:31 -0500 Message-ID: <4B798D2F.7010701@zytor.com> Date: Mon, 15 Feb 2010 10:06:39 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.7) Gecko/20100120 Fedora/3.0.1-1.fc12 Thunderbird/3.0.1 MIME-Version: 1.0 To: Oleg Nesterov CC: Linus Torvalds , Roland McGrath , linux-kernel@vger.kernel.org Subject: Re: x86: get rid of the insane TIF_ABI_PENDING bit References: <20100215161752.GA19962@redhat.com> <4B7974F7.1030105@zytor.com> <20100215165012.GA20447@redhat.com> In-Reply-To: <20100215165012.GA20447@redhat.com> 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 02/15/2010 08:50 AM, Oleg Nesterov wrote: > > Could you please point me where do we check TS_COMPAT during return > to user-mode? > Sorry, I was thinking about TIF_IA32, which is examined on line 415 of entry_64.S. >>> If a 64bit task execs a 32bit app, can't this TS_COMPAT break, say, >>> syscall_get_arguments() ? >> >> At that point (this is after the exec!) we don't get arguments anyway. > > I meant /proc/pid/syscall, but even if I am right this probably > doesn't matter. What does getting the arguments from a process which has never done a system call yet even mean? Presumably we get some kind of "null answer" which depends on the default register set; in that case the compat null answer is the correct one. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.