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=-2.0 required=3.0 tests=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 4FCACC76190 for ; Thu, 25 Jul 2019 21:58:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 22894229F9 for ; Thu, 25 Jul 2019 21:58:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="sHapK5Dv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726862AbfGYV62 (ORCPT ); Thu, 25 Jul 2019 17:58:28 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:40794 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726380AbfGYV62 (ORCPT ); Thu, 25 Jul 2019 17:58:28 -0400 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=3G0DbANSEEz3gBLVg4LbmF0CvfiTNd4gqwl2oAi+YHw=; b=sHapK5Dv01/JCHeQu/SjqvySW pH6NXKfPa0ocMNU8dGO4QMKJt+V/hxIZBWxflM6ndEmDYOb+0THMyDtpoiwsq1QwIEczr5gydc+AX ukWeOWFYxCs1H6b9ICoaEjcsxGhK/oWcWJZ2XRa7t1VukD9tmGNPRuMHBe/ljDRZlPMihyMqVlK2D Zix8A5XlQ9FwZM/jPoOI9e2CCXMdN+i0KM+peI6omltOm/LQWwmL8ST1sdCM4dZxZpjZ50MpqviaZ xvkaCb3IbY8GQo0+w56JWRDQeiSn6vs2kO1h0XtKVS+EnAzq8fGF8RKxA0nrZQogQb0j3TfenlS3k s2G1lrXVA==; Received: from shell.armlinux.org.uk ([2001:4d48:ad52:3201:5054:ff:fe00:4ec]:37148) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1hqlkb-0002Yr-TM; Thu, 25 Jul 2019 22:58:14 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1hqlka-00062y-II; Thu, 25 Jul 2019 22:58:12 +0100 Date: Thu, 25 Jul 2019 22:58:12 +0100 From: Russell King - ARM Linux admin To: Matthew Wilcox Cc: Anshuman Khandual , Mark Rutland , Kees Cook , Sri Krishna chowdary , Ard Biesheuvel , Masahiro Yamada , Tetsuo Handa , x86@kernel.org, Dave Hansen , linux-kernel@vger.kernel.org, Steven Price , linux-mm@kvack.org, Mark Brown , Andrew Morton , Michal Hocko , linux-arm-kernel@lists.infradead.org Subject: Re: [RFC] mm/pgtable/debug: Add test validating architecture page table helpers Message-ID: <20190725215812.GN1330@shell.armlinux.org.uk> References: <1564037723-26676-1-git-send-email-anshuman.khandual@arm.com> <1564037723-26676-2-git-send-email-anshuman.khandual@arm.com> <20190725143920.GW363@bombadil.infradead.org> <20190725213858.GK1330@shell.armlinux.org.uk> <20190725214222.GG30641@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190725214222.GG30641@bombadil.infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 25, 2019 at 02:42:22PM -0700, Matthew Wilcox wrote: > On Thu, Jul 25, 2019 at 10:38:58PM +0100, Russell King - ARM Linux admin wrote: > > On Thu, Jul 25, 2019 at 07:39:21AM -0700, Matthew Wilcox wrote: > > > But 'page' isn't necessarily PMD-aligned. I don't think we can rely on > > > architectures doing the right thing if asked to make a PMD for a randomly > > > aligned page. > > > > > > How about finding the physical address of something like kernel_init(), > > > and using the corresponding pte/pmd/pud/p4d/pgd that encompasses that > > > address? It's also better to pass in the pfn/page rather than using global > > > variables to communicate to the test functions. > > > > There are architectures (32-bit ARM) where the kernel is mapped using > > section mappings, and we don't expect the Linux page table walking to > > work for section mappings. > > This test doesn't go so far as to insert the PTE/PMD/PUD/... into the > page tables. It merely needs an appropriately aligned PFN to create a > PTE/PMD/PUD/... from. Well, in any case, c085ac68 t kernel_init so I'm not sure that would be an improvement. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up