From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753204AbaE1LpJ (ORCPT ); Wed, 28 May 2014 07:45:09 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:55226 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751363AbaE1LpI (ORCPT ); Wed, 28 May 2014 07:45:08 -0400 Date: Wed, 28 May 2014 12:44:38 +0100 From: Will Deacon To: Larry Bassel Cc: Catalin Marinas , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linaro-kernel@lists.linaro.org" , "khilman@linaro.org" Subject: Re: [PATCH v5 2/2] arm64: enable context tracking Message-ID: <20140528114438.GF15222@arm.com> References: <1401130573-7443-1-git-send-email-larry.bassel@linaro.org> <1401130573-7443-3-git-send-email-larry.bassel@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1401130573-7443-3-git-send-email-larry.bassel@linaro.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Larry, On Mon, May 26, 2014 at 07:56:13PM +0100, Larry Bassel wrote: > Make calls to ct_user_enter when the kernel is exited > and ct_user_exit when the kernel is entered (in el0_da, > el0_ia, el0_svc, el0_irq and all of the "error" paths). > > These macros expand to function calls which will only work > properly if el0_sync and related code has been rearranged > (in a previous patch of this series). > > The calls to ct_user_exit are made after hw debugging has been > enabled (enable_dbg_and_irq). > > The call to ct_user_enter is made at the beginning of the > kernel_exit macro. > > This patch is based on earlier work by Kevin Hilman. > Save/restore optimizations were also done by Kevin. Apologies if we've discussed this before (it rings a bell), but why are we penalising the fast syscall path with this? Shouldn't TIF_NOHZ contribute to out _TIF_WORK_MASK, then we could do the tracking on the syscall slow path? I think that would tidy up your mov into x19 too. Also -- how do you track ret_from_fork in the child with these patches? Will