From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755875Ab2HTJIJ (ORCPT ); Mon, 20 Aug 2012 05:08:09 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:56813 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754313Ab2HTJIG (ORCPT ); Mon, 20 Aug 2012 05:08:06 -0400 Date: Mon, 20 Aug 2012 10:07:54 +0100 From: Will Deacon To: Arnd Bergmann Cc: Catalin Marinas , "linux-arch@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "ulrich.weigand@linaro.org" Subject: Re: [PATCH v2 23/31] arm64: Debugging support Message-ID: <20120820090754.GB25864@mudshark.cambridge.arm.com> References: <1344966752-16102-1-git-send-email-catalin.marinas@arm.com> <20120816104748.GI31784@mudshark.cambridge.arm.com> <201208161249.35008.arnd@arndb.de> <201208170706.07821.arnd@arndb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201208170706.07821.arnd@arndb.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 17, 2012 at 08:06:07AM +0100, Arnd Bergmann wrote: > Sorry for the dumb question, but why do you even need PTRACE_GET_THREAD_AREA > for 64 bit tasks? I thought the thread pointer is a GPR, or is this just > for compat tasks? The TLS is stored in a co-processor register which is read-only for userspace. However, it's banked, so accessing the TLS of your child (the guy you're ptracing) requires a system call. Will