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,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 5DE9BC43603 for ; Mon, 16 Dec 2019 20:56:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2DF5021582 for ; Mon, 16 Dec 2019 20:56:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="kdLKoTmc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726828AbfLPU4e (ORCPT ); Mon, 16 Dec 2019 15:56:34 -0500 Received: from lelv0143.ext.ti.com ([198.47.23.248]:50890 "EHLO lelv0143.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726530AbfLPU4e (ORCPT ); Mon, 16 Dec 2019 15:56:34 -0500 Received: from fllv0034.itg.ti.com ([10.64.40.246]) by lelv0143.ext.ti.com (8.15.2/8.15.2) with ESMTP id xBGKuS7U072912; Mon, 16 Dec 2019 14:56:28 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1576529788; bh=HbeVMB6LPXMwO1eiEhfGjS8GhC3Lp6KRPVkA0Q8dXnY=; h=Subject:From:To:CC:References:Date:In-Reply-To; b=kdLKoTmcSpymDQMLowlHoKCYmsXTwfGshaG2OEOFQKxZiN5rudDLep+33WaUmpcFc hPqcYwThgoJrQJsgVwRstNBff18Py4XL+obGQVu1PecRw+NmKYpHC1v+ywuKTakxwD oog2eB7EqBM8SbO9V76DAT7Y5W4EevNllZa5MOHk= Received: from DFLE113.ent.ti.com (dfle113.ent.ti.com [10.64.6.34]) by fllv0034.itg.ti.com (8.15.2/8.15.2) with ESMTPS id xBGKuSgk115333 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 16 Dec 2019 14:56:28 -0600 Received: from DFLE109.ent.ti.com (10.64.6.30) by DFLE113.ent.ti.com (10.64.6.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1847.3; Mon, 16 Dec 2019 14:56:27 -0600 Received: from lelv0327.itg.ti.com (10.180.67.183) 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 via Frontend Transport; Mon, 16 Dec 2019 14:56:27 -0600 Received: from [10.250.79.55] (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0327.itg.ti.com (8.15.2/8.15.2) with ESMTP id xBGKuR2c102326; Mon, 16 Dec 2019 14:56:27 -0600 Subject: Re: [PATCH] ARM: OMAP: Use ARM SMC Calling Convention when OP-TEE is available From: "Andrew F. Davis" 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> Message-ID: <1ff8ae4b-5de3-4fdf-7318-d33398dc7fc8@ti.com> Date: Mon, 16 Dec 2019 15:56:27 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: 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 2:59 PM, Andrew F. Davis wrote: > 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. > Hi Tony, Looks like the TI quirk idea is not moving forward, even the QCOM quirk looks like it may get kicked out. arm_smccc_smc() will remain only for SMCCC compliant calls, but it looks like a generic arm_smc() wouldn't be too opposed upstream. Either way this patch would still be valid as when OP-TEE is present then arm_smccc_smc() will be the right call to make, how we handle the legacy calls can be sorted out later if a generic SMC call is implemented. Thanks, Andrew > Andrew > > >> $ git grep -C10 ARM_SMCCC_QUIRK_QCOM_A6 >> >> Regards, >> >> Tony >>