Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932965AbXK2SSt (ORCPT ); Thu, 29 Nov 2007 13:18:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932766AbXK2SSD (ORCPT ); Thu, 29 Nov 2007 13:18:03 -0500 Received: from mx1.redhat.com ([66.187.233.31]:53842 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933074AbXK2SSA (ORCPT ); Thu, 29 Nov 2007 13:18:00 -0500 Message-ID: <474F0243.1020103@redhat.com> Date: Thu, 29 Nov 2007 13:17:39 -0500 From: Chuck Ebbert Organization: Red Hat User-Agent: Thunderbird 1.5.0.12 (X11/20070719) MIME-Version: 1.0 To: Linus Torvalds CC: Roland McGrath , Andrew Morton , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Subject: Re: [PATCH x86/mm 6/6] x86-64 ia32 ptrace get/putreg32 current task References: <20071129003849.428E026F8E7@magilla.localdomain> <20071129004222.E49AD26F8E7@magilla.localdomain> <474EF824.3020806@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 701 Lines: 18 On 11/29/2007 01:09 PM, Linus Torvalds wrote: >>> case offsetof(struct user32, regs.gs): >>> *val = child->thread.gsindex; >>> + if (child == current) >>> + asm("movl %%gs,%0" : "=r" (*val)); >> Won't this return the kernel's GS instead of the user's? > > No, %gs is untouched by the kernel, so it contains user space version, and > getting the value directly from %gs looks correct. > But this is x86_64, where swapgs is done on kernel entry. - 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/