From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755459Ab2LRSpD (ORCPT ); Tue, 18 Dec 2012 13:45:03 -0500 Received: from terminus.zytor.com ([198.137.202.10]:60429 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752100Ab2LRSpB (ORCPT ); Tue, 18 Dec 2012 13:45:01 -0500 Message-ID: <50D0B986.7020009@zytor.com> Date: Tue, 18 Dec 2012 10:44:22 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Stefani Seibold CC: linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, ak@linux.intel.com, aarcange@redhat.com, john.stultz@linaro.org, luto@amacapital.net, xemul@parallels.com, gorcunov@openvz.org, andriy.shevchenko@linux.intel.com Subject: Re: [PATCH 6/6] Add 32 bit VDSO support for 32 and 64 bit kernels References: <1355823656-13902-1-git-send-email-stefani@seibold.net> <1355823656-13902-7-git-send-email-stefani@seibold.net> <50D09733.3080502@zytor.com> <1355849558.26967.24.camel@wall-e> In-Reply-To: <1355849558.26967.24.camel@wall-e> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/18/2012 08:52 AM, Stefani Seibold wrote: > > Pardon, i never disregarded nor i have agreed that this is going to be a > part of the VDSO. I currently have also no idea how to do this and i see > no need at the moment to do this revamp. The 64 bit VDSO lives since > more than 6 years with this kind of implementation. > It was part of this discussion thread, about how to best manage the address space. Fixed addresses are a major problem, and introducing new ones are extremely undesirable. Hence I wrote: > IMO it seems this is making it way more complicated than it is. Just > make sure you have a section in the vdso where you can map in a data > page with the symbols in the right offsets. Extra points for doing > magic so that it is at the beginning or end, but I think that might > be harder than necessary. Basically, make the vvar and hpet pages part of the vdso page list. Optionally they can be mapped without the MAYWRITE option -- in fact, we could easily split the vdso into an executable area which gets MAYWRITE to be able to set breakpoints and a data area which doesn't -- but that is a minor tweak IMO. > You asked me to do the VDSO 32 bit stuff for the IA32_EMULATION, before > it is ready for inclusion into the kernel. Thats exactly what i did. I > spend the whole weekend of my spare time to do this implementation. Now > we have them all. > > The patch works perfectly, all issues are solved: > > - Calling conventions > - ABI transformations > - System call gateway for X86 32 bit > - Mapping of the FIXMAP and HPET into the lower 32 bit address space for > IA32_EMULATION > - Support for 32 bit programs in 32 kernel and 64 bit kernel > - One VDSO source for all > > If you prefer an other solutions, its okay. There are many ways to code > things. But for now i think it is a good step ahead. That is what i > currently can provide. This is good. We have some time anyway to get this ready for the 3.9 merge window. -hpa