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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 CF689C432C0 for ; Tue, 19 Nov 2019 19:59:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A5B742240E for ; Tue, 19 Nov 2019 19:59:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="N/DT8ol2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727234AbfKST7X (ORCPT ); Tue, 19 Nov 2019 14:59:23 -0500 Received: from lelv0143.ext.ti.com ([198.47.23.248]:52716 "EHLO lelv0143.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726711AbfKST7X (ORCPT ); Tue, 19 Nov 2019 14:59:23 -0500 Received: from lelv0265.itg.ti.com ([10.180.67.224]) by lelv0143.ext.ti.com (8.15.2/8.15.2) with ESMTP id xAJJxHaf065912; Tue, 19 Nov 2019 13:59:17 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1574193557; bh=sFnvX7KanOuyc2mCyRNrw4h36+/QQx87wlOE/O0R8ac=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=N/DT8ol2qbcceUKxraQ3xHSBp+95hJC8bGMPnEZ3ZEtUZsiNoaUU1VTuatrO+FXSk WbXNdXkDdZdoTz90e6P5a/bs4ZvBF8BGkMUppMwj7ozNwOPwG++xD4/Dz+WTYxuDPv R9cDQ6JOCt06PhmtakjOZmn8JFtj40qFLSX/JJio= Received: from DFLE109.ent.ti.com (dfle109.ent.ti.com [10.64.6.30]) by lelv0265.itg.ti.com (8.15.2/8.15.2) with ESMTPS id xAJJxHtP013095 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 19 Nov 2019 13:59:17 -0600 Received: from DFLE101.ent.ti.com (10.64.6.22) by DFLE109.ent.ti.com (10.64.6.30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1847.3; Tue, 19 Nov 2019 13:59:17 -0600 Received: from fllv0039.itg.ti.com (10.64.41.19) by DFLE101.ent.ti.com (10.64.6.22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1847.3 via Frontend Transport; Tue, 19 Nov 2019 13:59:17 -0600 Received: from [10.250.45.147] (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0039.itg.ti.com (8.15.2/8.15.2) with ESMTP id xAJJxGQu095040; Tue, 19 Nov 2019 13:59:16 -0600 Subject: Re: [PATCH] ARM: OMAP: Use ARM SMC Calling Convention when OP-TEE is available To: Tony Lindgren CC: Mark Rutland , , References: <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> <20191119192029.GP35479@atomide.com> <0ad31b32-712e-5bef-5645-0336dfec99cc@ti.com> <20191119194425.GQ35479@atomide.com> From: "Andrew F. Davis" Message-ID: Date: Tue, 19 Nov 2019 14:59:11 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191119194425.GQ35479@atomide.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/19/19 2:44 PM, Tony Lindgren wrote: > * Andrew F. Davis [191119 19:36]: >> On 11/19/19 2:20 PM, Tony Lindgren wrote: >>> * 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. >> >> But we are not using generic API calls, we are using omap_smcx() which >> cannot call into arm_smccc_smc(). For all the above reasons plus >> arm_smccc_smc() uses r12 to save the stack pointer, our ROM expects r12 >> to store the function ID. > > Saving and restoring r12 could be handled by the arm_smccc_smc() quirk > for the non-optee case. > > Then we could get rid of omap_smc1() and arm_smccc_smc() should work > for the optee case and non-optee case, right. > Yes, we could have both cases working if we could get the quirk in. >>>>> 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? > >> They should not be needed at the same time, either OP-TEE is on the >> secure side or ROM is there. > > OK thanks. So we could just modify the code dynamically on boot > based on if optee is found or not. The quirk could be done along > the lines of the qcom quirk but only for the non-optee case: > We wouldn't have to patch anything if we could get the quirk in. One has to state they wish to use the quirk version in a structure passed into arm_smccc_smc_quirk(), in which case for all legacy user we just fill out this quirk struct. OP-TEE uses the same arm_smccc_smc() but without the quirk struct and so it uses the compliant call. The issue is still the same, I tried adding this, I got NAKd, if you want to convince Mark to change his mind and allow us the quirk then we can go down this path. Otherwise this will remain a dead end. Andrew > $ git grep -C10 ARM_SMCCC_QUIRK_QCOM_A6 > > Regards, > > Tony >