From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751168AbaEVU3W (ORCPT ); Thu, 22 May 2014 16:29:22 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:58757 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750870AbaEVU3V (ORCPT ); Thu, 22 May 2014 16:29:21 -0400 Message-ID: <537E5E1F.3050605@codeaurora.org> Date: Thu, 22 May 2014 16:29:19 -0400 From: Christopher Covington User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-Version: 1.0 To: Larry Bassel CC: catalin.marinas@arm.com, will.deacon@arm.com, khilman@linaro.org, linaro-kernel@lists.linaro.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v4 2/2] arm64: enable context tracking References: <1400786855-32656-1-git-send-email-larry.bassel@linaro.org> <1400786855-32656-3-git-send-email-larry.bassel@linaro.org> In-Reply-To: <1400786855-32656-3-git-send-email-larry.bassel@linaro.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Larry, On 05/22/2014 03:27 PM, 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. > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -30,6 +30,44 @@ > #include > > /* > + * Context tracking subsystem. Used to instrument transitions > + * between user and kernel mode. > + */ > + .macro ct_user_exit, restore = 0 > +#ifdef CONFIG_CONTEXT_TRACKING > + bl context_tracking_user_exit > + .if \restore == 1 > + /* > + * Save/restore needed during syscalls. Restore syscall arguments from > + * the values already saved on stack during kernel_entry. > + */ > + ldp x0, x1, [sp] > + ldp x2, x3, [sp, #S_X2] > + ldp x4, x5, [sp, #S_X4] > + ldp x6, x7, [sp, #S_X6] > + .endif > +#endif > + .endm > + > + .macro ct_user_enter, save = 0 > +#ifdef CONFIG_CONTEXT_TRACKING > + .if \save == 1 > + /* > + * Save/restore only needed on syscall fastpath, which uses > + * x0-x2. > + */ > + push x2, x3 Why is x3 saved? > + push x0, x1 > + .endif > + bl context_tracking_user_enter > + .if \save == 1 > + pop x0, x1 > + pop x2, x3 > + .endif > +#endif > + .endm Thanks, Christopher -- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation.