From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754879Ab2ASAlr (ORCPT ); Wed, 18 Jan 2012 19:41:47 -0500 Received: from terminus.zytor.com ([198.137.202.10]:33679 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750954Ab2ASAlp (ORCPT ); Wed, 18 Jan 2012 19:41:45 -0500 Message-ID: <4F176605.5020101@zytor.com> Date: Wed, 18 Jan 2012 16:38:29 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111115 Thunderbird/8.0 MIME-Version: 1.0 To: Linus Torvalds CC: Roland McGrath , Indan Zupancic , Andi Kleen , Jamie Lokier , Andrew Lutomirski , Oleg Nesterov , Will Drewry , linux-kernel@vger.kernel.org, keescook@chromium.org, john.johansen@canonical.com, serge.hallyn@canonical.com, coreyb@linux.vnet.ibm.com, pmoore@redhat.com, eparis@redhat.com, djm@mindrot.org, segoon@openwall.com, rostedt@goodmis.org, jmorris@namei.org, scarybeasts@gmail.com, avi@redhat.com, penberg@cs.helsinki.fi, viro@zeniv.linux.org.uk, mingo@elte.hu, akpm@linux-foundation.org, khilman@ti.com, borislav.petkov@amd.com, amwang@redhat.com, ak@linux.intel.com, eric.dumazet@gmail.com, gregkh@suse.de, dhowells@redhat.com, daniel.lezcano@free.fr, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, olofj@chromium.org, mhalcrow@google.com, dlaor@redhat.com Subject: Re: Compat 32-bit syscall entry from 64-bit task!? References: <20120116183730.GB21112@redhat.com> <49017bd7edab7010cd9ac767e39d99e4.squirrel@webmail.greenhost.nl> <20120118015013.GR11715@one.firstfloor.org> <20120118020453.GL7180@jl-vm1.vm.bytemark.co.uk> <20120118022217.GS11715@one.firstfloor.org> <4F1731C1.4050007@zytor.com> <4F1733DF.7040905@zytor.com> <4F1737C9.3070905@zytor.com> <4F173F48.2070604@zytor.com> In-Reply-To: X-Enigmail-Version: 1.3.4 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 01/18/2012 03:28 PM, Linus Torvalds wrote: > On Wed, Jan 18, 2012 at 1:53 PM, H. Peter Anvin wrote: >> >> I think we can obviously agree that regsets is the only way to go for >> any kind of new state. > > So I really don't necessarily agree at all. > > Exactly because there is a heavy burden to introducing new models. > It's not only relatively much more kernel code, it's also relatively > much more painful for user code. If we can hide it in existing > structures, user code is *much* better off, because any existing code > to get the state will just continue to work. Otherwise, you need to > have the code to figure out the new structures (how do you compile it > without the new kernel headers?), you need to do the extra accesses > conditionally etc etc. > > There's a real cost to introducing new interfaces. There's a *reason* > people try to make do with old ones. > Of course. However, the whole point with regsets is that at the very least the vast majority of the infrastructure is generic and extends without a bunch of new machine. What you are saying is "we might be able to get away with existing state", what I'm saying is "if we add state it should be a regset". The question if this should be new state is currently open. I personally would still would prefer if this didn't overlay real CPU state. -hpa From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: Compat 32-bit syscall entry from 64-bit task!? Date: Wed, 18 Jan 2012 16:38:29 -0800 Message-ID: <4F176605.5020101@zytor.com> References: <20120116183730.GB21112@redhat.com> <49017bd7edab7010cd9ac767e39d99e4.squirrel@webmail.greenhost.nl> <20120118015013.GR11715@one.firstfloor.org> <20120118020453.GL7180@jl-vm1.vm.bytemark.co.uk> <20120118022217.GS11715@one.firstfloor.org> <4F1731C1.4050007@zytor.com> <4F1733DF.7040905@zytor.com> <4F1737C9.3070905 @zytor.com> <4F173F48.2070604@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Roland McGrath , Indan Zupancic , Andi Kleen , Jamie Lokier , Andrew Lutomirski , Oleg Nesterov , Will Drewry , linux-kernel@vger.kernel.org, keescook@chromium.org, john.johansen@canonical.com, serge.hallyn@canonical.com, coreyb@linux.vnet.ibm.com, pmoore@redhat.com, eparis@redhat.com, djm@mindrot.org, segoon@openwall.com, rostedt@goodmis.org, jmorris@namei.org, scarybeasts@gmail.com, avi@redhat.com, penberg@cs.helsinki.fi, viro@zeniv.linux.org.uk, mingo@elte.hu, akpm@linux-foundation.org, khilman@ti.com, borislav.petkov@amd.com, amwang@redhat.com, ak@linux.intel.com, eric.dumazet@gmail.com, gregkh@suse.de, dhowells@redhat.com, daniel.lezcano@free.fr, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, olofj@chromium.org, mh To: Linus Torvalds Return-path: In-Reply-To: Sender: linux-security-module-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On 01/18/2012 03:28 PM, Linus Torvalds wrote: > On Wed, Jan 18, 2012 at 1:53 PM, H. Peter Anvin wrote: >> >> I think we can obviously agree that regsets is the only way to go for >> any kind of new state. > > So I really don't necessarily agree at all. > > Exactly because there is a heavy burden to introducing new models. > It's not only relatively much more kernel code, it's also relatively > much more painful for user code. If we can hide it in existing > structures, user code is *much* better off, because any existing code > to get the state will just continue to work. Otherwise, you need to > have the code to figure out the new structures (how do you compile it > without the new kernel headers?), you need to do the extra accesses > conditionally etc etc. > > There's a real cost to introducing new interfaces. There's a *reason* > people try to make do with old ones. > Of course. However, the whole point with regsets is that at the very least the vast majority of the infrastructure is generic and extends without a bunch of new machine. What you are saying is "we might be able to get away with existing state", what I'm saying is "if we add state it should be a regset". The question if this should be new state is currently open. I personally would still would prefer if this didn't overlay real CPU state. -hpa