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=-6.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,T_MIXED_ES, 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 3BC41C65BAE for ; Thu, 13 Dec 2018 15:04:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 01A102086D for ; Thu, 13 Dec 2018 15:04:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 01A102086D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729492AbeLMPEB (ORCPT ); Thu, 13 Dec 2018 10:04:01 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:35742 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728620AbeLMPEB (ORCPT ); Thu, 13 Dec 2018 10:04:01 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9D1E780D; Thu, 13 Dec 2018 07:04:00 -0800 (PST) Received: from [10.1.197.36] (e112298-lin.cambridge.arm.com [10.1.197.36]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A90AF3F614; Thu, 13 Dec 2018 07:03:58 -0800 (PST) Subject: Re: [PATCH v7 11/25] arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking From: Julien Thierry To: Ard Biesheuvel Cc: linux-arm-kernel , Linux Kernel Mailing List , Daniel Thompson , joel@joelfernandes.org, Marc Zyngier , Christoffer Dall , James Morse , Catalin Marinas , Will Deacon , Mark Rutland , oleg@redhat.com References: <1544633245-6036-1-git-send-email-julien.thierry@arm.com> <1544633245-6036-12-git-send-email-julien.thierry@arm.com> <19500d6b-62a3-21cb-9ac0-a4e5d4714a63@arm.com> <31e41461-763f-aa7d-91ea-b493ede81eed@arm.com> Message-ID: Date: Thu, 13 Dec 2018 15:03:57 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13/12/2018 12:02, Julien Thierry wrote: > > > On 13/12/2018 11:35, Ard Biesheuvel wrote: >> On Thu, 13 Dec 2018 at 09:54, Julien Thierry wrote: >>> >>> >>> >>> On 12/12/2018 18:10, Ard Biesheuvel wrote: >>>> On Wed, 12 Dec 2018 at 18:59, Julien Thierry wrote: >>>>> >>>>> >>>>> >>>>> On 12/12/2018 17:27, Ard Biesheuvel wrote: >>>>>> On Wed, 12 Dec 2018 at 17:48, Julien Thierry wrote: >>>>>>> >>>>>>> Instead disabling interrupts by setting the PSR.I bit, use a priority >>>>>>> higher than the one used for interrupts to mask them via PMR. >>>>>>> >>>>>>> When using PMR to disable interrupts, the value of PMR will be used >>>>>>> instead of PSR.[DAIF] for the irqflags. >>>>>>> >>>>>>> Signed-off-by: Julien Thierry >>>>>>> Suggested-by: Daniel Thompson >>>>>>> Cc: Catalin Marinas >>>>>>> Cc: Will Deacon >>>>>>> Cc: Ard Biesheuvel >>>>>>> Cc: Oleg Nesterov >>>>>>> --- >>>>>>> arch/arm64/include/asm/efi.h | 5 +- >>>>>>> arch/arm64/include/asm/irqflags.h | 123 +++++++++++++++++++++++++++++--------- >>>>>>> 2 files changed, 99 insertions(+), 29 deletions(-) >>>>>>> >>>>>>> diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h >>>>>>> index 7ed3208..a9d3ebc 100644 >>>>>>> --- a/arch/arm64/include/asm/efi.h >>>>>>> +++ b/arch/arm64/include/asm/efi.h >>>>>>> @@ -42,7 +42,10 @@ >>>>>>> >>>>>>> efi_status_t __efi_rt_asm_wrapper(void *, const char *, ...); >>>>>>> >>>>>>> -#define ARCH_EFI_IRQ_FLAGS_MASK (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT) >>>>>>> +#define ARCH_EFI_IRQ_FLAGS_MASK \ >>>>>>> + (system_uses_irq_prio_masking() ? \ >>>>>>> + GIC_PRIO_IRQON : \ >>>>>>> + (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT)) >>>>>>> >>>>>> >>>>>> This mask is used to determine whether we return from a firmware call >>>>>> with a different value for the I flag than we entered it with. So >>>>>> instead of changing the mask, we should change the way we record DAIF, >>>>>> given that the firmware is still going to poke the I bit if it >>>>>> misbehaves, regardless of whether the OS happens to use priorities for >>>>>> interrupt masking. >>>>>> >>>>> >>>>> Thanks for pointing that out, so this change makes little sense... >>>>> >>>>> The annoying part is that the flag checking takes place in the arch >>>>> agnostic code. >>>>> >>>>> Would introducing some overriddable efi_get_flags() or efi_save_flags() >>>>> that default to local_save_flags() seem like an acceptable solution? >>>>> >>>>> This way I could override it for arm64 and still return the DAIF bits. >>>>> >>>> >>>> I don't follow the reasoning below about irqflags exactly, but is >>>> there any way we could simply but both PMR and DAIF in flags? We could >>>> even update the mask here to ensure that the firmware doesn't corrupt >>>> the PMR. >>>> >>> >>> So, that was the case in my previous versions of the series, and as you >>> said, that covered checking both DAIF bits and PMR on return from EFI >>> services. But Catalin suggested that irqflags could just use PMR when we >>> enable the priority masking feature. Catalin's suggestion does simplify >>> things, except for this part. >>> >>> However, it doesn't seem to far-fetched to me that the architecture >>> could have a more generic way to tell the EFI driver "this is the set of >>> stuff that I care about and you should return from runtime services with >>> this stuff in the same state as before" without the "set of stuff" being >>> limited to irqflags. >>> >>> But maybe this would be over-engineering just to deal with my use-case... >>> >> >> No, that makes sense. As you said, you can just create a >> efi_get_irqflags() helper that defaults to what we are using now, and >> can be overridden to just return DAIF in our case. >> > > Good, thanks for the confirmation. I'll do that for the next version of > the series. > Argh, not as simple as I had expected. Turns out include/linux/efi.h does not include asm/efi.h (including it at the beginning of the file breaks the build because asm/efi.h misses the efi type definitions. So a thing like: #ifndef efi_get_irqflags #define efi_get_irqflags(flags) local_save_flags(flags) #endif in include/linux/efi.h cannot be overridden. Either I would need to introduce the definitions arm, arm64 and x86 (I don't think there are other arch supporting EFI right now) or I'll need to come up with another solution. -- Julien Thierry 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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,T_MIXED_ES,URIBL_BLOCKED autolearn=unavailable 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 F232CC65BAE for ; Thu, 13 Dec 2018 15:04:17 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BECEA2087F for ; 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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gXSX9-00042M-PJ; Thu, 13 Dec 2018 15:04:15 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gXSX5-0003u8-J3 for linux-arm-kernel@lists.infradead.org; Thu, 13 Dec 2018 15:04:13 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9D1E780D; Thu, 13 Dec 2018 07:04:00 -0800 (PST) Received: from [10.1.197.36] (e112298-lin.cambridge.arm.com [10.1.197.36]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A90AF3F614; Thu, 13 Dec 2018 07:03:58 -0800 (PST) Subject: Re: [PATCH v7 11/25] arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking From: Julien Thierry To: Ard Biesheuvel References: <1544633245-6036-1-git-send-email-julien.thierry@arm.com> <1544633245-6036-12-git-send-email-julien.thierry@arm.com> <19500d6b-62a3-21cb-9ac0-a4e5d4714a63@arm.com> <31e41461-763f-aa7d-91ea-b493ede81eed@arm.com> Message-ID: Date: Thu, 13 Dec 2018 15:03:57 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181213_070411_735036_B15AB908 X-CRM114-Status: GOOD ( 26.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Daniel Thompson , Marc Zyngier , Catalin Marinas , Will Deacon , Linux Kernel Mailing List , Christoffer Dall , James Morse , oleg@redhat.com, joel@joelfernandes.org, linux-arm-kernel Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 13/12/2018 12:02, Julien Thierry wrote: > > > On 13/12/2018 11:35, Ard Biesheuvel wrote: >> On Thu, 13 Dec 2018 at 09:54, Julien Thierry wrote: >>> >>> >>> >>> On 12/12/2018 18:10, Ard Biesheuvel wrote: >>>> On Wed, 12 Dec 2018 at 18:59, Julien Thierry wrote: >>>>> >>>>> >>>>> >>>>> On 12/12/2018 17:27, Ard Biesheuvel wrote: >>>>>> On Wed, 12 Dec 2018 at 17:48, Julien Thierry wrote: >>>>>>> >>>>>>> Instead disabling interrupts by setting the PSR.I bit, use a priority >>>>>>> higher than the one used for interrupts to mask them via PMR. >>>>>>> >>>>>>> When using PMR to disable interrupts, the value of PMR will be used >>>>>>> instead of PSR.[DAIF] for the irqflags. >>>>>>> >>>>>>> Signed-off-by: Julien Thierry >>>>>>> Suggested-by: Daniel Thompson >>>>>>> Cc: Catalin Marinas >>>>>>> Cc: Will Deacon >>>>>>> Cc: Ard Biesheuvel >>>>>>> Cc: Oleg Nesterov >>>>>>> --- >>>>>>> arch/arm64/include/asm/efi.h | 5 +- >>>>>>> arch/arm64/include/asm/irqflags.h | 123 +++++++++++++++++++++++++++++--------- >>>>>>> 2 files changed, 99 insertions(+), 29 deletions(-) >>>>>>> >>>>>>> diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h >>>>>>> index 7ed3208..a9d3ebc 100644 >>>>>>> --- a/arch/arm64/include/asm/efi.h >>>>>>> +++ b/arch/arm64/include/asm/efi.h >>>>>>> @@ -42,7 +42,10 @@ >>>>>>> >>>>>>> efi_status_t __efi_rt_asm_wrapper(void *, const char *, ...); >>>>>>> >>>>>>> -#define ARCH_EFI_IRQ_FLAGS_MASK (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT) >>>>>>> +#define ARCH_EFI_IRQ_FLAGS_MASK \ >>>>>>> + (system_uses_irq_prio_masking() ? \ >>>>>>> + GIC_PRIO_IRQON : \ >>>>>>> + (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT)) >>>>>>> >>>>>> >>>>>> This mask is used to determine whether we return from a firmware call >>>>>> with a different value for the I flag than we entered it with. So >>>>>> instead of changing the mask, we should change the way we record DAIF, >>>>>> given that the firmware is still going to poke the I bit if it >>>>>> misbehaves, regardless of whether the OS happens to use priorities for >>>>>> interrupt masking. >>>>>> >>>>> >>>>> Thanks for pointing that out, so this change makes little sense... >>>>> >>>>> The annoying part is that the flag checking takes place in the arch >>>>> agnostic code. >>>>> >>>>> Would introducing some overriddable efi_get_flags() or efi_save_flags() >>>>> that default to local_save_flags() seem like an acceptable solution? >>>>> >>>>> This way I could override it for arm64 and still return the DAIF bits. >>>>> >>>> >>>> I don't follow the reasoning below about irqflags exactly, but is >>>> there any way we could simply but both PMR and DAIF in flags? We could >>>> even update the mask here to ensure that the firmware doesn't corrupt >>>> the PMR. >>>> >>> >>> So, that was the case in my previous versions of the series, and as you >>> said, that covered checking both DAIF bits and PMR on return from EFI >>> services. But Catalin suggested that irqflags could just use PMR when we >>> enable the priority masking feature. Catalin's suggestion does simplify >>> things, except for this part. >>> >>> However, it doesn't seem to far-fetched to me that the architecture >>> could have a more generic way to tell the EFI driver "this is the set of >>> stuff that I care about and you should return from runtime services with >>> this stuff in the same state as before" without the "set of stuff" being >>> limited to irqflags. >>> >>> But maybe this would be over-engineering just to deal with my use-case... >>> >> >> No, that makes sense. As you said, you can just create a >> efi_get_irqflags() helper that defaults to what we are using now, and >> can be overridden to just return DAIF in our case. >> > > Good, thanks for the confirmation. I'll do that for the next version of > the series. > Argh, not as simple as I had expected. Turns out include/linux/efi.h does not include asm/efi.h (including it at the beginning of the file breaks the build because asm/efi.h misses the efi type definitions. So a thing like: #ifndef efi_get_irqflags #define efi_get_irqflags(flags) local_save_flags(flags) #endif in include/linux/efi.h cannot be overridden. Either I would need to introduce the definitions arm, arm64 and x86 (I don't think there are other arch supporting EFI right now) or I'll need to come up with another solution. -- Julien Thierry _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel