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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=ham 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 E7E44C433DB for ; Fri, 26 Mar 2021 12:19:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8C6361948 for ; Fri, 26 Mar 2021 12:19:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229904AbhCZMTS (ORCPT ); Fri, 26 Mar 2021 08:19:18 -0400 Received: from foss.arm.com ([217.140.110.172]:58358 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229882AbhCZMTJ (ORCPT ); Fri, 26 Mar 2021 08:19:09 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 22468143D; Fri, 26 Mar 2021 05:19:09 -0700 (PDT) Received: from C02TD0UTHF1T.local (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8E9043F7D7; Fri, 26 Mar 2021 05:19:05 -0700 (PDT) Date: Fri, 26 Mar 2021 12:18:50 +0000 From: Mark Rutland To: Sudeep Holla Cc: linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, Trilok Soni , arve@android.com, Andrew Walbran , David Hartley , Achin Gupta , Jens Wiklander , Arunachalam Ganapathy , Marc Bonnici , Catalin Marinas , Will Deacon , Michael Kelley Subject: Re: [PATCH v5 2/7] arm64: smccc: Add support for SMCCCv1.2 input/output registers Message-ID: <20210326121833.GA56294@C02TD0UTHF1T.local> References: <20210325143255.1532452-1-sudeep.holla@arm.com> <20210325143255.1532452-3-sudeep.holla@arm.com> <20210325144113.GB41100@C02TD0UTHF1T.local> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210325144113.GB41100@C02TD0UTHF1T.local> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Thu, Mar 25, 2021 at 02:41:13PM +0000, Mark Rutland wrote: > Hi Sudeep, > > On Thu, Mar 25, 2021 at 02:32:50PM +0000, Sudeep Holla wrote: > > SMCCC v1.2 allows x8-x17 to be used as parameter registers and x4—x17 > > to be used as result registers in SMC64/HVC64. Arm Firmware Framework > > for Armv8-A specification makes use of x0-x7 as parameter and result > > registers. > > > > Current SMCCC interface in the kernel just use x0-x7 as parameter and > > x0-x3 as result registers. Let us add new interface to support x0-x7 > > as parameter and result registers. This can be extended to include > > x8-x17 when there are users for the same. > > Michael Kelley is also looking at using SMCCCv1.2, and on his HyperV > thread I'd suggested we should deal with the whole set of SMCCCv1.2 > registers now to avoid future churn in this area (using struct both for > the arguments and return values). > > How painful would it be to extend this patch to do that? I *think* the major change with this would be making the interfaces: void arm_smccc_1_2_{hvc,smc}(struct arm_smccc_1_2_args *args, struct arm_smccc_1_2_res *res); ... and callers manipulating the structs directly, with arm64 having more fields, e.g. // arm64 struct arm_smccc_1_2_args { unsigned long a1; ... unsigned long a17; } struct arm_smccc_1_2_res { unsigned long a0; ... unsigned long a17; } // arm struct arm_smccc_1_2_args { unsigned long a1; ... unsigned long a7; } struct arm_smccc_1_2_res { unsigned long a0; ... unsigned long a7; } I think that can be hidden in the FF-A wrappers, so that doesn't need to be what FF-A drivers see. Does that sound plausible, or is that painful? > > + DEFINE(ARM_SMCCC_V1_2_RES_X0_OFFS, offsetof(struct arm_smccc_v1_2_res, a0)); As a general nit, for consistency with the existing arm_smccc_1_1 code, could we please drop the 'V' in these names, and use `ARM_SMCCC_1_2` or `arm_smccc_1_2` ? FWIW, other than the above comments, this all looks good to me Thanks, Mark. > > diff --git a/arch/arm64/kernel/smccc-call.S b/arch/arm64/kernel/smccc-call.S > > index d62447964ed9..0ea15c1742f3 100644 > > --- a/arch/arm64/kernel/smccc-call.S > > +++ b/arch/arm64/kernel/smccc-call.S > > @@ -43,3 +43,25 @@ SYM_FUNC_START(__arm_smccc_hvc) > > SMCCC hvc > > SYM_FUNC_END(__arm_smccc_hvc) > > EXPORT_SYMBOL(__arm_smccc_hvc) > > + > > + .macro SMCCC_v1_2 instr > > + .cfi_startproc > > + \instr #0 > > + ldr x8, [sp] > > + stp x0, x1, [x8, #ARM_SMCCC_V1_2_RES_X0_OFFS] > > + stp x2, x3, [x8, #ARM_SMCCC_V1_2_RES_X2_OFFS] > > + stp x4, x5, [x8, #ARM_SMCCC_V1_2_RES_X4_OFFS] > > + stp x6, x7, [x8, #ARM_SMCCC_V1_2_RES_X6_OFFS] > > + ret > > + .cfi_endproc > > +.endm > > + > > +SYM_FUNC_START(arm_smccc_v1_2_hvc) > > + SMCCC_v1_2 hvc > > +SYM_FUNC_END(arm_smccc_v1_2_hvc) > > +EXPORT_SYMBOL(arm_smccc_v1_2_hvc) > > + > > +SYM_FUNC_START(arm_smccc_v1_2_smc) > > + SMCCC_v1_2 smc > > +SYM_FUNC_END(arm_smccc_v1_2_smc) > > +EXPORT_SYMBOL(arm_smccc_v1_2_smc) > > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h > > index 62c54234576c..0b8fa285a054 100644 > > --- a/include/linux/arm-smccc.h > > +++ b/include/linux/arm-smccc.h > > @@ -186,6 +186,56 @@ struct arm_smccc_res { > > unsigned long a3; > > }; > > > > +#ifdef CONFIG_ARM64 > > +/* TODO Need to implement for ARM too */ > > +/** > > + * struct arm_smccc_v1_2_res - Result from SMC/HVC call > > + * @a0-a7 result values from registers 0 to 7 > > + */ > > +struct arm_smccc_v1_2_res { > > + unsigned long a0; > > + unsigned long a1; > > + unsigned long a2; > > + unsigned long a3; > > + unsigned long a4; > > + unsigned long a5; > > + unsigned long a6; > > + unsigned long a7; > > +}; > > + > > +/** > > + * arm_smccc_v1_2_hvc() - make HVC calls > > + * @a0-a7: arguments passed in registers 0 to 7 > > + * @res: result values from registers 0 to 7 > > + * > > + * This function is used to make HVC calls following SMC Calling Convention > > + * v1.2 or above. The content of the supplied param are copied to registers > > + * 0 to 7 prior to the HVC instruction. The return values are updated with > > + * the content from register 0 to 7 on return from the HVC instruction. > > + */ > > +asmlinkage > > +void arm_smccc_v1_2_hvc(unsigned long a0, unsigned long a1, unsigned long a2, > > + unsigned long a3, unsigned long a4, unsigned long a5, > > + unsigned long a6, unsigned long a7, > > + struct arm_smccc_v1_2_res *res); > > + > > +/** > > + * arm_smccc_v1_2_smc() - make SMC calls > > + * @a0-a7: arguments passed in registers 0 to 7 > > + * @res: result values from registers 0 to 7 > > + * > > + * This function is used to make SMC calls following SMC Calling Convention > > + * v1.2 or above. The content of the supplied param are copied to registers > > + * 0 to 7 prior to the SMC instruction. The return values are updated with > > + * the content from register 0 to 7 on return from the SMC instruction. > > + */ > > +asmlinkage > > +void arm_smccc_v1_2_smc(unsigned long a0, unsigned long a1, unsigned long a2, > > + unsigned long a3, unsigned long a4, unsigned long a5, > > + unsigned long a6, unsigned long a7, > > + struct arm_smccc_v1_2_res *res); > > +#endif > > + > > /** > > * struct arm_smccc_quirk - Contains quirk information > > * @id: quirk identification > > -- > > 2.25.1 > > > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel