Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754026AbaBBA1J (ORCPT ); Sat, 1 Feb 2014 19:27:09 -0500 Received: from terminus.zytor.com ([198.137.202.10]:37015 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750985AbaBBA1G (ORCPT ); Sat, 1 Feb 2014 19:27:06 -0500 Message-ID: <52ED90A3.9080802@zytor.com> Date: Sat, 01 Feb 2014 16:26:11 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Andy Lutomirski , Stefani Seibold CC: Greg KH , "linux-kernel@vger.kernel.org" , X86 ML , Thomas Gleixner , Ingo Molnar , Andi Kleen , Andrea Arcangeli , John Stultz , Pavel Emelyanov , Cyrill Gorcunov , andriy.shevchenko@linux.intel.com, Martin.Runge@rohde-schwarz.com, Andreas.Brief@rohde-schwarz.com Subject: Re: [PATCH 3/4] Add 32 bit VDSO time support for 32 bit kernel References: <1391268756-10766-1-git-send-email-stefani@seibold.net> <1391268756-10766-4-git-send-email-stefani@seibold.net> In-Reply-To: X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/01/2014 03:59 PM, Andy Lutomirski wrote: > > If it is, indeed, okay to use non-fixed maps on 32-bit, it might > also be okay on 64-bit. If so, it could be useful to implement that, > which would remove a bit of a wart and allow PR_SET_TSC to work > usefully for 64-bit userspace. (This would remove the need for the > VVAR macro and would allow shorter rip-relative address modes.) > We can't really move the 64-bit legacy vsyscall area, though, as it is an ABI. It can be disabled with vsyscall=none, but Linus has vehemently vetoed removing them. > (Note that those fixmaps are a security problem on native 32-bit if > NX is not available. We may not care.) Not only on native 32 bit... although the amount of 64-bit hardware without NX is quite small, the same is true for anywhere near modern 32-bit hardware. >> >> -#define VDSO_HIGH_BASE 0xffffe000U /* CONFIG_COMPAT_VDSO address */ >> +#define VDSO_HIGH_BASE 0xffffc000U /* CONFIG_COMPAT_VDSO address */ > > This is odd. Can you explain it? > He needs 3 pages instead of 1 after his changes. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/