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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 D7269C33CB3 for ; Tue, 28 Jan 2020 06:13:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9DC2024685 for ; Tue, 28 Jan 2020 06:13:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=c-s.fr header.i=@c-s.fr header.b="C70j0unK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726010AbgA1GNL (ORCPT ); Tue, 28 Jan 2020 01:13:11 -0500 Received: from pegase1.c-s.fr ([93.17.236.30]:50715 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725774AbgA1GNL (ORCPT ); Tue, 28 Jan 2020 01:13:11 -0500 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 486GWR2cqXz9v22Q; Tue, 28 Jan 2020 07:13:07 +0100 (CET) Authentication-Results: localhost; dkim=pass reason="1024-bit key; insecure key" header.d=c-s.fr header.i=@c-s.fr header.b=C70j0unK; dkim-adsp=pass; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id tf9SBshBmIx8; Tue, 28 Jan 2020 07:13:07 +0100 (CET) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 486GWR19WTz9v22N; Tue, 28 Jan 2020 07:13:07 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=c-s.fr; s=mail; t=1580191987; bh=pcrCnDSka2qoXBfBeA3afQal2h0amq4PFi2jmMQwdpk=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=C70j0unKrMF6yDixdWedTQC2P5T5/vAYpEmpZheamqM8tUIvuDuoyzTfclHpLcmBs zFelibkah4ATRqmpbd//5eGzB63dcgYhxVJrzK4IvtVG6rBysf1zACi5HU+mamJ97b k3ddSc1LOjJeLmYIAzLxKGYzTukejGmyrGraiJB8= Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id DCAFB8B7C2; Tue, 28 Jan 2020 07:13:07 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id UqMMVHvL2Had; Tue, 28 Jan 2020 07:13:07 +0100 (CET) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 1FF9D8B75B; Tue, 28 Jan 2020 07:13:05 +0100 (CET) Subject: Re: [PATCH V12] mm/debug: Add tests validating architecture page table helpers To: Qian Cai , Anshuman Khandual Cc: Linux-MM , Andrew Morton , Vlastimil Babka , Greg Kroah-Hartman , Thomas Gleixner , Mike Rapoport , Jason Gunthorpe , Dan Williams , Peter Zijlstra , Michal Hocko , Mark Rutland , Mark Brown , Steven Price , Ard Biesheuvel , Masahiro Yamada , Kees Cook , Tetsuo Handa , Matthew Wilcox , Sri Krishna chowdary , Dave Hansen , Russell King - ARM Linux , Michael Ellerman , Paul Mackerras , Martin Schwidefsky , Heiko Carstens , "David S. Miller" , Vineet Gupta , James Hogan , Paul Burton , Ralf Baechle , "Kirill A . Shutemov" , Gerald Schaefer , Ingo Molnar , linux-snps-arc@lists.infradead.org, linux-mips@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org References: <1580174873-18117-1-git-send-email-anshuman.khandual@arm.com> <14882A91-17DE-4ABD-ABF2-08E7CCEDF660@lca.pw> <214c0d53-eb34-9b0c-2e4e-1aa005146331@arm.com> <016A776F-EFD9-4D2B-A3A9-788008617D95@lca.pw> From: Christophe Leroy Message-ID: Date: Tue, 28 Jan 2020 07:13:04 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: <016A776F-EFD9-4D2B-A3A9-788008617D95@lca.pw> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org Le 28/01/2020 à 04:33, Qian Cai a écrit : > > >> On Jan 27, 2020, at 10:06 PM, Anshuman Khandual wrote: >> >> >> >> On 01/28/2020 07:41 AM, Qian Cai wrote: >>> >>> >>>> On Jan 27, 2020, at 8:28 PM, Anshuman Khandual wrote: >>>> >>>> This adds tests which will validate architecture page table helpers and >>>> other accessors in their compliance with expected generic MM semantics. >>>> This will help various architectures in validating changes to existing >>>> page table helpers or addition of new ones. >>>> >>>> This test covers basic page table entry transformations including but not >>>> limited to old, young, dirty, clean, write, write protect etc at various >>>> level along with populating intermediate entries with next page table page >>>> and validating them. >>>> >>>> Test page table pages are allocated from system memory with required size >>>> and alignments. The mapped pfns at page table levels are derived from a >>>> real pfn representing a valid kernel text symbol. This test gets called >>>> right after page_alloc_init_late(). >>>> >>>> This gets build and run when CONFIG_DEBUG_VM_PGTABLE is selected along with >>>> CONFIG_VM_DEBUG. Architectures willing to subscribe this test also need to >>>> select CONFIG_ARCH_HAS_DEBUG_VM_PGTABLE which for now is limited to x86 and >>>> arm64. Going forward, other architectures too can enable this after fixing >>>> build or runtime problems (if any) with their page table helpers. >> >> Hello Qian, >> >>> >>> What’s the value of this block of new code? It only supports x86 and arm64 >>> which are supposed to be good now. >> >> We have been over the usefulness of this code many times before as the patch is >> already in it's V12. Currently it is enabled on arm64, x86 (except PAE), arc and >> ppc32. There are build time or runtime problems with other archs which prevent > > I am not sure if I care too much about arc and ppc32 which are pretty much legacy > platforms. > >> enablement of this test (for the moment) but then the goal is to integrate all >> of them going forward. The test not only validates platform's adherence to the >> expected semantics from generic MM but also helps in keeping it that way during >> code changes in future as well. > > Another option maybe to get some decent arches on board first before merging this > thing, so it have more changes to catch regressions for developers who might run this. > ppc32 an indecent / legacy platform ? Are you kidying ? Powerquicc II PRO for instance is fully supported by the manufacturer and widely used in many small networking devices. Christophe