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=-2.2 required=3.0 tests=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 BD9FEC432C0 for ; Tue, 19 Nov 2019 16:22:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9229A222A2 for ; Tue, 19 Nov 2019 16:22:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728471AbfKSQWB (ORCPT ); Tue, 19 Nov 2019 11:22:01 -0500 Received: from muru.com ([72.249.23.125]:42904 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726307AbfKSQWB (ORCPT ); Tue, 19 Nov 2019 11:22:01 -0500 Received: from atomide.com (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id 47F57809B; Tue, 19 Nov 2019 16:22:37 +0000 (UTC) Date: Tue, 19 Nov 2019 08:21:57 -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: <20191119162157.GJ35479@atomide.com> References: <20191118165236.22136-1-afd@ti.com> <20191118215759.GD35479@atomide.com> <20191118223128.GE35479@atomide.com> <29db708e-119e-8a89-7d43-e38e2a10dc07@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <29db708e-119e-8a89-7d43-e38e2a10dc07@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 01:14]: > On 11/18/19 5:31 PM, Tony Lindgren wrote: > > * Andrew F. Davis [191118 22:14]: > >> On 11/18/19 4:57 PM, Tony Lindgren wrote: > >>> Hi, > >>> > >>> * Andrew F. Davis [191118 08:53]: > >>>> +#define OMAP_SIP_SMC_STD_CALL_VAL(func_num) \ > >>>> + ARM_SMCCC_CALL_VAL(ARM_SMCCC_STD_CALL, ARM_SMCCC_SMC_32, \ > >>>> + ARM_SMCCC_OWNER_SIP, (func_num)) > >>>> + > >>>> +void omap_smc1(u32 fn, u32 arg) > >>>> +{ > >>>> + struct device_node *optee; > >>>> + struct arm_smccc_res res; > >>>> + > >>>> + /* > >>>> + * If this platform has OP-TEE installed we use ARM SMC calls > >>>> + * otherwise fall back to the OMAP ROM style calls. > >>>> + */ > >>>> + optee = of_find_node_by_path("/firmware/optee"); > >>>> + if (optee) { > >>>> + arm_smccc_smc(OMAP_SIP_SMC_STD_CALL_VAL(fn), arg, > >>>> + 0, 0, 0, 0, 0, 0, &res); > >>>> + WARN(res.a0, "Secure function call 0x%08x failed\n", fn); > >>>> + } else { > >>>> + _omap_smc1(fn, arg); > >>>> + } > >>>> +} > >>> > >>> I think we're better off just making arm_smccc_smc() work properly. > >>> See cat arch/arm*/kernel/smccc-call.S. > >>> > >> > >> > >> arm_smccc_smc() does work properly already, I'm using it here. > > > > OK. I guess I don't follow then why we can't use arm_smccc_smc() > > for old code. > > > > > Our ROM code needs r12 to have the function code in it, where as the ARM > SMC calling convention standard requires that (plus some other > information) stored in r0. Our ROM doesn't know anything about the that > standard that came out years after we shipped these devices. And as such > is not complaint. Right. > A generic smc() call would be nice, but arm_smccc_smc() is specifically > for SMCCC. To me it seeems that HAVE_ARM_SMCCC is a generic feature though. It's not limited to OPTEE. We have select HAVE_ARM_SMCCC if CPU_V7 in arch/arm/Kconfig, and OPTEE depends on HAVE_ARM_SMCCC. >From that point of view it seems that we could have HAVE_ARM_SMCCC enabled also for v6 and use it for all mach-omap2 with a wrapper. So I'd like to have our smc callers eventually just call generic generic arm_smccc_smc(OMAP_SIP_SMC_STD_CALL_VAL(fn)...) rather than the custom calls. And we want to update to using the generic functions one case at a time as the features get tested :) In any case, you should do the necessary checks for HAVE_ARM_SMCCC only once during init. I'm not sure how much checking for "/firmware/optee" helps here, sounds like we have a broken system if the firmware is not there while the arm_smccc_smc() should still work just fine :) Regards, Tony