From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266136AbUBCTXX (ORCPT ); Tue, 3 Feb 2004 14:23:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266129AbUBCTXX (ORCPT ); Tue, 3 Feb 2004 14:23:23 -0500 Received: from mail.shareable.org ([81.29.64.88]:27342 "EHLO mail.shareable.org") by vger.kernel.org with ESMTP id S266051AbUBCSXs (ORCPT ); Tue, 3 Feb 2004 13:23:48 -0500 Date: Tue, 3 Feb 2004 18:23:10 +0000 From: Jamie Lokier To: Andrea Arcangeli Cc: Ulrich Drepper , john stultz , lkml Subject: Re: [RFC][PATCH] linux-2.6.2-rc2_vsyscall-gtod_B1.patch Message-ID: <20040203182310.GA18326@mail.shareable.org> References: <1075344395.1592.87.camel@cog.beaverton.ibm.com> <401894DA.7000609@redhat.com> <20040201012803.GN26076@dualathlon.random> <401F251C.2090300@redhat.com> <20040203085224.GA15738@mail.shareable.org> <20040203162515.GY26076@dualathlon.random> <20040203173716.GC17895@mail.shareable.org> <20040203181001.GA26076@dualathlon.random> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040203181001.GA26076@dualathlon.random> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrea Arcangeli wrote: > vsyscalls will never execute anything like execve. They can at most > modify userspace memory a fixed address, so if the userspace isn't > fixed, then nothing can be done with a vsyscall. Are we talking about the same x86_64? I see this in arch/x86_64/vsyscall.S: __kernel_vsyscall: .LSTART_vsyscall: push %ebp .Lpush_ebp: movl %ecx, %ebp syscall Is that page not mapped into userspace? If the answer is no, then btw we were talking about i386 until you joined in. :) The "sysenter" instruction is definitely mapped into userspace there. -- Jamie