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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id A8520C021B8 for ; Tue, 4 Mar 2025 14:13:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:CC:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Cz7IA69OFA9tHcBAPSVOCjGmnTTL7mvde1OZORF4svs=; b=IkjF1jSE80siRyFFgvwi6yq2uw YPqGifkoqpAf5C6UCBvwbO5HiB2sD1u8tP1IywZRoC7QWRaGURP/Pbo+noMUm6ZlXzDebPYwnOvsj pZg6bPQVaYzyLSc9gFpV+tN4MH3F76Qfjfr74an3o/CDR2rKKm/C4L2AT7ulgsRX1ePtCW2B7j3Bd IN+FHE68LPeLjYudRzP9+Sm8eGI/dYoFJ8PYD3+EtBZ9ozSjUmVciviCiK4zCFKUbPbhIyPJ3UJ5d Qsn+YW1LZG416V6MQVzy7tf9I3Un4BFsk7awLlcTuGDNHm8Q7A11kZcsHpPTA70/01BtrQjk3PR0M UC4maxzg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tpT1H-00000004w5k-2APM; Tue, 04 Mar 2025 14:13:15 +0000 Received: from szxga05-in.huawei.com ([45.249.212.191]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tpSzB-00000004vbe-04U5 for linux-arm-kernel@lists.infradead.org; Tue, 04 Mar 2025 14:11:06 +0000 Received: from mail.maildlp.com (unknown [172.19.163.17]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4Z6ctR2c3Gz1ltZw; Tue, 4 Mar 2025 22:06:39 +0800 (CST) Received: from kwepemk500005.china.huawei.com (unknown [7.202.194.90]) by mail.maildlp.com (Postfix) with ESMTPS id B226C1A0188; Tue, 4 Mar 2025 22:10:50 +0800 (CST) Received: from [10.174.179.234] (10.174.179.234) by kwepemk500005.china.huawei.com (7.202.194.90) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Tue, 4 Mar 2025 22:10:48 +0800 Message-ID: <2c1fa758-c292-aefb-f6e2-cab41f592568@huawei.com> Date: Tue, 4 Mar 2025 22:10:47 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH v13 4/5] arm64: support copy_mc_[user]_highpage() To: Catalin Marinas CC: Mark Rutland , Jonathan Cameron , Mauro Carvalho Chehab , Will Deacon , Andrew Morton , James Morse , Robin Murphy , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Michael Ellerman , Nicholas Piggin , Andrey Ryabinin , Alexander Potapenko , Christophe Leroy , Aneesh Kumar K.V , "Naveen N. Rao" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , , "H. Peter Anvin" , Madhavan Srinivasan , , , , , , , Guohanjun References: <20241209024257.3618492-1-tongtiangen@huawei.com> <20241209024257.3618492-5-tongtiangen@huawei.com> <69955002-c3b1-459d-9b42-8d07475c3fd3@huawei.com> <3b181285-2ff3-b77a-867b-725f38ea86d3@huawei.com> From: Tong Tiangen In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.234] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemk500005.china.huawei.com (7.202.194.90) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250304_061105_479735_991D3A81 X-CRM114-Status: GOOD ( 19.92 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi,Catalin: Kindly ping ... Thanks.:) 在 2025/2/19 3:42, Catalin Marinas 写道: > On Tue, Feb 18, 2025 at 07:51:10PM +0800, Tong Tiangen wrote: >>>>>> 在 2025/2/13 1:11, Catalin Marinas 写道: >>>>>>> On Mon, Dec 09, 2024 at 10:42:56AM +0800, Tong Tiangen wrote: >>>>>>>> Currently, many scenarios that can tolerate memory errors when copying page >>>>>>>> have been supported in the kernel[1~5], all of which are implemented by >>>>>>>> copy_mc_[user]_highpage(). arm64 should also support this mechanism. >>>>>>>> >>>>>>>> Due to mte, arm64 needs to have its own copy_mc_[user]_highpage() >>>>>>>> architecture implementation, macros __HAVE_ARCH_COPY_MC_HIGHPAGE and >>>>>>>> __HAVE_ARCH_COPY_MC_USER_HIGHPAGE have been added to control it. >>>>>>>> >>>>>>>> Add new helper copy_mc_page() which provide a page copy implementation with >>>>>>>> hardware memory error safe. The code logic of copy_mc_page() is the same as >>>>>>>> copy_page(), the main difference is that the ldp insn of copy_mc_page() >>>>>>>> contains the fixup type EX_TYPE_KACCESS_ERR_ZERO_MEM_ERR, therefore, the >>>>>>>> main logic is extracted to copy_page_template.S. In addition, the fixup of >>>>>>>> MOPS insn is not considered at present. >>>>>>> >>>>>>> Could we not add the exception table entry permanently but ignore the >>>>>>> exception table entry if it's not on the do_sea() path? That would save >>>>>>> some code duplication. > [...] >> So we need another way to distinguish the different processing of the >> same exception type on SEA and non-SEA path. > > Distinguishing whether the fault is SEA or non-SEA is already done by > the exception handling you are adding. What we don't have though is > information about whether the caller invoked copy_highpage() or > copy_mc_highpage(). That's where the code duplication comes in handy. > > It's a shame we need to duplicate identical functions just to have > different addresses to look up in the exception table. We are also short > of caller saved registers to track this information (e.g. an extra > argument to those functions that the exception handler interprets). > > I need to think a bit more, we could in theory get the arm64 memcpy_mc() > to return an error code depending on what type of fault it got (e.g. > -EHWPOISON for SEA, -EFAULT for non-SEA). copy_mc_highpage() would > interpret this one and panic if -EFAULT. But we lose some fault details > we normally get on a faulty access like some of the registers. > > Well, maybe the simples is still to keep the function duplication. I'll > have another look at the series tomorrow. >