From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F4D5C432C0 for ; Tue, 19 Nov 2019 19:20:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E24322440 for ; Tue, 19 Nov 2019 19:20:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727031AbfKSTUe (ORCPT ); Tue, 19 Nov 2019 14:20:34 -0500 Received: from muru.com ([72.249.23.125]:42964 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726555AbfKSTUd (ORCPT ); Tue, 19 Nov 2019 14:20:33 -0500 Received: from atomide.com (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id CE0E0809B; Tue, 19 Nov 2019 19:21:09 +0000 (UTC) Date: Tue, 19 Nov 2019 11:20:29 -0800 From: Tony Lindgren To: "Andrew F. Davis" Cc: Mark Rutland , linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ARM: OMAP: Use ARM SMC Calling Convention when OP-TEE is available Message-ID: <20191119192029.GP35479@atomide.com> References: <29db708e-119e-8a89-7d43-e38e2a10dc07@ti.com> <20191119162157.GJ35479@atomide.com> <6e009ae3-6aa2-409b-749f-4947303940d8@ti.com> <20191119164227.GL35479@atomide.com> <20191119180546.GM35479@atomide.com> <9e15c170-c9fa-778c-d998-bd1111a6390d@ti.com> <20191119183247.GN35479@atomide.com> <20191119190721.GO35479@atomide.com> <7fa11037-8d33-2274-c8cc-80e9630b38b0@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7fa11037-8d33-2274-c8cc-80e9630b38b0@ti.com> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andrew F. Davis [191119 19:13]: > On 11/19/19 2:07 PM, Tony Lindgren wrote: > > * Andrew F. Davis [191119 18:51]: > >> On 11/19/19 1:32 PM, Tony Lindgren wrote: > >>> It would allow us to completely change over to using > >>> arm_smccc_smc() and forget the custom calls. > >> > >> We would need more than just the r12 quirk to replace all our custom SMC > >> handlers, we would need quirks for omap_smc2 which puts process ID in r1 > >> and puts #0xff in r6, and omap_smc3 that uses smc #1. All of our legacy > >> SMC calls also trash r4-r11, that is very non SMCCC complaint as only > >> r4-r7 need be caller saved. I don't see arm_smccc_smc() working with > >> legacy ROM no matter how much we hack at it :( > > > > We would just have omap_smc2() call arm_smccc_smc() and in that > > case. And omap_smc2() would still deal with saving and restoring > > the registers. > > Then why call arm_smccc_smc()? omap_smc2() is already an assembly > function, all it needs to do after loading the registers and saving the > right ones is issue an "smc #0" instruction, why would we want to > instead call into some other function to re-save registers and issue the > exact same instruction? To use Linux generic API for smc calls where possible. > > Certainly the wrapper functions calling arm_smccc_smc() can deal > > with r12 too if the r12-quirk version and the plain version are > > never needed the same time on a booted SoC. > > > > Are they ever needed the same time on a booted SoC or not? ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Sorry but maybe check the font size on your screen. I'm trying to get your attention again for the second time above to answer a question I asked. > >> I can make OP-TEE also compatible with the r12 quirk, which is what I > >> used to do. That way we didn't need to do any detection. The issue was > >> that non-standard SMC calls should not go through the common SMCCC > >> handler (unless you are QCOM for some reason..). > > > > Sounds like for optee nothing must be done for r12 :) > Unless all our calls use the r12 hack, then we would need to fixup > OP-TEE to accept that also. No idea about that that part, but sounds like r12 use is up to the caller in the optee case. Regards, Tony