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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 BC710C6379D for ; Fri, 27 Nov 2020 08:22:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 68139221FF for ; Fri, 27 Nov 2020 08:22:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727362AbgK0IWc (ORCPT ); Fri, 27 Nov 2020 03:22:32 -0500 Received: from pegase1.c-s.fr ([93.17.236.30]:42979 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726849AbgK0IWb (ORCPT ); Fri, 27 Nov 2020 03:22:31 -0500 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 4Cj70L68dcz9tyqT; Fri, 27 Nov 2020 09:22:26 +0100 (CET) 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 NtGH_xBF8Vrp; Fri, 27 Nov 2020 09:22:26 +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 4Cj70L5DgCz9tyqS; Fri, 27 Nov 2020 09:22:26 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id B48428B811; Fri, 27 Nov 2020 09:22:26 +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 oukQXGOE9kwa; Fri, 27 Nov 2020 09:22:26 +0100 (CET) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id B1CD28B80F; Fri, 27 Nov 2020 09:22:25 +0100 (CET) Subject: Re: [PATCH 1/2] mm/debug_vm_pgtable/basic: Add validation for dirtiness after write protect To: Anshuman Khandual , linux-mm@kvack.org, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, catalin.marinas@arm.com, steven.price@arm.com, gerald.schaefer@linux.ibm.com, vgupta@synopsys.com, paul.walmsley@sifive.com References: <1606453584-15399-1-git-send-email-anshuman.khandual@arm.com> <1606453584-15399-2-git-send-email-anshuman.khandual@arm.com> From: Christophe Leroy Message-ID: Date: Fri, 27 Nov 2020 09:22:24 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <1606453584-15399-2-git-send-email-anshuman.khandual@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 27/11/2020 à 06:06, Anshuman Khandual a écrit : > This adds validation tests for dirtiness after write protect conversion for > each page table level. This is important for platforms such as arm64 that > removes the hardware dirty bit while making it an write protected one. This > also fixes pxx_wrprotect() related typos in the documentation file. > > diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c > index c05d9dcf7891..a5be11210597 100644 > --- a/mm/debug_vm_pgtable.c > +++ b/mm/debug_vm_pgtable.c > @@ -70,6 +70,7 @@ static void __init pte_basic_tests(unsigned long pfn, pgprot_t prot) > WARN_ON(pte_young(pte_mkold(pte_mkyoung(pte)))); > WARN_ON(pte_dirty(pte_mkclean(pte_mkdirty(pte)))); > WARN_ON(pte_write(pte_wrprotect(pte_mkwrite(pte)))); > + WARN_ON(pte_dirty(pte_wrprotect(pte))); Wondering what you are testing here exactly. Do you expect that if PTE has the dirty bit, it gets cleared by pte_wrprotect() ? Powerpc doesn't do that, it only clears the RW bit but the dirty bit remains if it is set, until you call pte_mkclean() explicitely. > } > > static void __init pte_advanced_tests(struct mm_struct *mm, > @@ -144,6 +145,7 @@ static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot) > WARN_ON(pmd_young(pmd_mkold(pmd_mkyoung(pmd)))); > WARN_ON(pmd_dirty(pmd_mkclean(pmd_mkdirty(pmd)))); > WARN_ON(pmd_write(pmd_wrprotect(pmd_mkwrite(pmd)))); > + WARN_ON(pmd_dirty(pmd_wrprotect(pmd))); > /* > * A huge page does not point to next level page table > * entry. Hence this must qualify as pmd_bad(). > @@ -262,6 +264,7 @@ static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) > WARN_ON(!pud_write(pud_mkwrite(pud_wrprotect(pud)))); > WARN_ON(pud_write(pud_wrprotect(pud_mkwrite(pud)))); > WARN_ON(pud_young(pud_mkold(pud_mkyoung(pud)))); > + WARN_ON(pud_dirty(pud_wrprotect(pud))); > > if (mm_pmd_folded(mm)) > return; > Christophe