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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 B35A5C433E0 for ; Tue, 29 Dec 2020 10:53:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 83CE2207CC for ; Tue, 29 Dec 2020 10:53:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726396AbgL2Kwu (ORCPT ); Tue, 29 Dec 2020 05:52:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53232 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725866AbgL2Kwu (ORCPT ); Tue, 29 Dec 2020 05:52:50 -0500 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7976CC0613D6 for ; Tue, 29 Dec 2020 02:51:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=hqlpDHbQI+IW+gacvz8RsUWJocaaMYB1ckj8x8KROw0=; b=AO8NMCaTYDMv/EwFlPSCdX9J9 VAWyxsNdUR+qLwEiVbRNMWsZepOuWbRz4CPwoRq40Hzf53li8G9gECptV+7+e6/DmVdMXIcRV8dmE ATupU0LKG0rOhWJ0vBeCreOkPSEW1MEeu+cxAz0UWj35Jo9kHEQ5Al6sTwb4987FZ9Vk2NbJ6os5z mCuXM3q2WLrXDUgyj7PrnDvmLIjHFoB8IyshbJ2JLi8Pj7S9tbtg1gVMQSkmhS58V8dyerfjftOGg h4LmT400Kd81UdQBlwDJnN6OGH0+/cCV0sJneYXZblEi1Eoi2t4GlVVE/t89vdwibFsklzQ1VM2Z/ JwPDZOnhQ==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:44866) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kuCbT-00053K-8j; Tue, 29 Dec 2020 10:51:47 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1kuCbP-0001Ae-S2; Tue, 29 Dec 2020 10:51:43 +0000 Date: Tue, 29 Dec 2020 10:51:43 +0000 From: Russell King - ARM Linux admin To: "Leizhen (ThunderTown)" Cc: Greg Kroah-Hartman , Will Deacon , Jason Cooper , Haojian Zhuang , Arnd Bergmann , linux-arm-kernel , linux-kernel Subject: Re: [PATCH 1/1] ARM: LPAE: use phys_addr_t instead of unsigned long in outercache hooks Message-ID: <20201229105143.GL1551@shell.armlinux.org.uk> References: <20201225114458.1334-1-thunder.leizhen@huawei.com> <20201226121346.GB1551@shell.armlinux.org.uk> <3a597586-2bce-66cf-b9f8-4bb667a600d0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3a597586-2bce-66cf-b9f8-4bb667a600d0@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King - ARM Linux admin Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 29, 2020 at 02:30:56PM +0800, Leizhen (ThunderTown) wrote: > > > On 2020/12/26 20:13, Russell King - ARM Linux admin wrote: > > On Fri, Dec 25, 2020 at 07:44:58PM +0800, Zhen Lei wrote: > >> The outercache of some Hisilicon SOCs support physical addresses wider > >> than 32-bits. The unsigned long datatype is not sufficient for mapping > >> physical addresses >= 4GB. The commit ad6b9c9d78b9 ("ARM: 6671/1: LPAE: > >> use phys_addr_t instead of unsigned long in outercache functions") has > >> already modified the outercache functions. But the parameters of the > >> outercache hooks are not changed. This patch use phys_addr_t instead of > >> unsigned long in outercache hooks: inv_range, clean_range, flush_range. > >> > >> To ensure the outercache that does not support LPAE works properly, do > >> cast phys_addr_t to unsigned long by adding a middle-tier function. > > > > Please don't do that. The cast can be done inside the L2 functions > > themselves without needing all these additional functions. > > OK. At first, I wanted to fit in like this: > > -static void l2c220_inv_range(unsigned long start, unsigned long end) > +static void l2c220_inv_range(phys_addr_t lpae_start, phys_addr_t lpae_end) > { > + unsigned long start = lpae_start; > + unsigned long end = lpae_end; It sounds like there should be a "but..." clause here. This is exactly what I'm suggesting you should be doing. Currently, there's a silent narrowing cast in every single caller of the outer_.*_range() functions and you're only moving it from the callsites to inside the called functions. > > We probably ought to also add some protection against addresses > 4GB, > > although these are hot paths, so we don't want to add tests in these > > functions. Maybe instead checking whether the system has memory above > > 4GB while the L2 cache is being initialised would be a good idea? > > I'm sorry, I didn't quite understand what you meant. Currently, the > biggest problem is the compilation problem. The sizeof(long) may be > 32, and the 64-bit physical address cannot be transferred from outcache > functions to outcache hooks. What I mean is that we really ought to warn if the L2C310 code tries to initialise on a system where memory is above 4GB. However, it's very unlikely that such a system exists, so it's probably fine not implement a check, but it just feels fragile to be truncating the 64-bit address to 32-bit on a kernel that _could_ support higher addresses, even though that's exactly what is happening today (kind of by accident - I don't think anyone realised.) -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!