From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753235Ab1HEUhE (ORCPT ); Fri, 5 Aug 2011 16:37:04 -0400 Received: from terminus.zytor.com ([198.137.202.10]:45681 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752563Ab1HEUhC (ORCPT ); Fri, 5 Aug 2011 16:37:02 -0400 Message-ID: <4E3C5460.90505@zytor.com> Date: Fri, 05 Aug 2011 13:36:48 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:5.0) Gecko/20110707 Thunderbird/5.0 MIME-Version: 1.0 To: Andi Kleen CC: luto@mit.edu, x86@kernel.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, lueckintel@yahoo.com, kimwooyoung@gmail.com Subject: Re: New vsyscall emulation breaks JITs References: <20110805200945.GA14014@tassilo.jf.intel.com> <4E3C5154.2050307@zytor.com> <20110805202656.GI5782@one.firstfloor.org> In-Reply-To: <20110805202656.GI5782@one.firstfloor.org> 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 08/05/2011 01:26 PM, Andi Kleen wrote: >> I have to say I believe that trying to JIT the vdso or vsyscall pages is >> extremely dubious at best. They are fundamentally different from normal >> user space in that the kernel can muck with them any time, without >> notifying userspace about it. The other aspect of this is that this is >> about the legacy vsyscall page, which we're trying to get rid of, partly >> because of security problems. > > There's clear evidence now you can't: it's used even by new binaries. time() is not supported by vdso; this is a problem. Getting rid of it is a long-term thing. -hpa