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 010E4C76190 for ; Thu, 25 Jul 2019 21:39:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C5BD2218D4 for ; Thu, 25 Jul 2019 21:39:30 +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="eLpLsIpH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726803AbfGYVj3 (ORCPT ); Thu, 25 Jul 2019 17:39:29 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:40490 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725819AbfGYVj3 (ORCPT ); Thu, 25 Jul 2019 17:39:29 -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=Kavq+eip1im675O4/bBLmRIQNPqz1C3eZxq/uo8ufXg=; b=eLpLsIpHT3C0NpVJISxE4wDFP 0m9PzZxBOyaV1z++UwBohppQQiDGlRoxJgo8tE7vvbhAe0pv+aRmtEdRR79cc8X1YcIrIpfQrmeyO EFzavlvQKFeMAPS54eto2mb6JhC0HxzSj38xaLArlIOk7NxOpTKvVDSbeKuD03Mli22Mu7hNeqZEM SkZ6oXyf3A+yKcqm6Xk45/zIAP3YQV3zX7VmOauPyiBxJ5XH1H9lcgUkMY/B0Erq2DOy/5UdosSfp hkRP/vFoPTpMcJI4fOfZhjaZwLZ24C3sKtAqcajQ7tHjWA6lfmcEN/ctpkjvb6ZeQNA7U/yIjfXDq 6W1P95aSw==; Received: from shell.armlinux.org.uk ([2002:4e20:1eda:1:5054:ff:fe00:4ec]:44656) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1hqlS8-0002Sy-46; Thu, 25 Jul 2019 22:39:08 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1hqlRy-00061g-Ob; Thu, 25 Jul 2019 22:38:58 +0100 Date: Thu, 25 Jul 2019 22:38:58 +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: <20190725213858.GK1330@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190725143920.GW363@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 07:39:21AM -0700, Matthew Wilcox wrote: > On Thu, Jul 25, 2019 at 12:25:23PM +0530, Anshuman Khandual wrote: > > This adds a test module which will validate architecture page table helpers > > and accessors regarding compliance with generic MM semantics expectations. > > This will help various architectures in validating changes to the existing > > page table helpers or addition of new ones. > > I think this is a really good idea. > > > lib/Kconfig.debug | 14 +++ > > lib/Makefile | 1 + > > lib/test_arch_pgtable.c | 290 ++++++++++++++++++++++++++++++++++++++++++++++++ > > Is this the right place for it? I worry that lib/ is going to get overloaded > with test code, and this feels more like mm/ test code. > > > +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE > > +static void pmd_basic_tests(void) > > +{ > > + pmd_t pmd; > > + > > + pmd = mk_pmd(page, prot); > > 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. > > + /* > > + * A huge page does not point to next level page table > > + * entry. Hence this must qualify as pmd_bad(). > > + */ > > + WARN_ON(!pmd_bad(pmd_mkhuge(pmd))); > > I didn't know that rule. This is helpful because it gives us somewhere > to document all these tricksy little rules. > > > +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD > > +static void pud_basic_tests(void) > > Is this the right ifdef? > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > -- 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