From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932308AbaEGKRl (ORCPT ); Wed, 7 May 2014 06:17:41 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:62728 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754598AbaEGKRk (ORCPT ); Wed, 7 May 2014 06:17:40 -0400 Date: Wed, 7 May 2014 11:17:09 +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 v2 2/2] arm64: enable context tracking Message-ID: <20140507101709.GE18456@arm.com> References: <1399419149-26685-1-git-send-email-larry.bassel@linaro.org> <1399419149-26685-3-git-send-email-larry.bassel@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1399419149-26685-3-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 On Wed, May 07, 2014 at 12:32:29AM +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). Why only these entry points? I can reschedule after any exception from EL0, so I'd expect all exceptions from userspace to need annotating, no? > 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). > > In order to avoid saving registers, the slow syscall path > is forced (as x86 does). ... and if you decide to handle undef exceptions, I think you'll need the register saving too, in case the kernel needs to perform emulation. Will