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,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 2F6D0C65BAE for ; Thu, 13 Dec 2018 12:02:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E4B112086D for ; Thu, 13 Dec 2018 12:02:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E4B112086D 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 S1728835AbeLMMCq (ORCPT ); Thu, 13 Dec 2018 07:02:46 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:60312 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728733AbeLMMCq (ORCPT ); Thu, 13 Dec 2018 07:02:46 -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 B9D2BA78; Thu, 13 Dec 2018 04:02:45 -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 6AD643F575; Thu, 13 Dec 2018 04:02:43 -0800 (PST) Subject: Re: [PATCH v7 11/25] arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking 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> From: Julien Thierry Message-ID: Date: Thu, 13 Dec 2018 12:02:40 +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 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. Thanks, -- 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,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 91BD9C67839 for ; Thu, 13 Dec 2018 12:03:03 +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 623E62086D for ; Thu, 13 Dec 2018 12:03:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="cca1dZ7e" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 623E62086D 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-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=RIhu8yY2d4VNx2KSschWujUNYgdgyTT+V9f4sYA7vCY=; b=cca1dZ7eM0ttxK AVXGNFzdUZHF4ViMaNoj1gKJSOysXlqYgjZuqMF1qMXWYp4gVdTRSdL2NDp90iGjso3HEytwhtgho lzTOyc5u2jeSOnUarxwAgf7llfWkMuB9tYHoFBua+hyGxy+6WfHyKIwrSwLe0WtdTxw+z2oke9IHe hKg80hTDkcdTNCXir1o+KlIOH8Kzuc8P0ukWCcyCZ9HM1lIa2HlzBHgQMq0X9bVYJxo3G/8zezVWZ B0zYkMPn9GKlOUDysSJs4X0wQ1lYwfdNUoXrE0b8bc3s8Kg26hOoKrFyJNmQ+aKyP5cKtkhYsw6qD mBUejzXmUCvnCXzs4hsA==; 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 1gXPhj-0004Gl-Sc; Thu, 13 Dec 2018 12:02:59 +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 1gXPhg-0004G7-Cg for linux-arm-kernel@lists.infradead.org; Thu, 13 Dec 2018 12:02:57 +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 B9D2BA78; Thu, 13 Dec 2018 04:02:45 -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 6AD643F575; Thu, 13 Dec 2018 04:02:43 -0800 (PST) Subject: Re: [PATCH v7 11/25] arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking 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> From: Julien Thierry Message-ID: Date: Thu, 13 Dec 2018 12:02:40 +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_040256_437936_9A469C83 X-CRM114-Status: GOOD ( 26.32 ) 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 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. Thanks, -- Julien Thierry _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel