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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 DB0A8C4320D for ; Wed, 25 Sep 2019 02:59:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A7DE72146E for ; Wed, 25 Sep 2019 02:59:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7DE72146E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 58BBB6B0269; Tue, 24 Sep 2019 22:59:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5393F6B026A; Tue, 24 Sep 2019 22:59:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 476B16B026B; Tue, 24 Sep 2019 22:59:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0220.hostedemail.com [216.40.44.220]) by kanga.kvack.org (Postfix) with ESMTP id 273EB6B0269 for ; Tue, 24 Sep 2019 22:59:49 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id BBB7D180AD802 for ; Wed, 25 Sep 2019 02:59:48 +0000 (UTC) X-FDA: 75971938056.24.humor11_383d11124cd32 X-HE-Tag: humor11_383d11124cd32 X-Filterd-Recvd-Size: 3256 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf23.hostedemail.com (Postfix) with ESMTP for ; Wed, 25 Sep 2019 02:59:46 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 106711596; Tue, 24 Sep 2019 19:59:46 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.40.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C6F0C3F694; Tue, 24 Sep 2019 19:59:40 -0700 (PDT) From: Jia He To: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Marc Zyngier , Matthew Wilcox , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose Cc: Punit Agrawal , Anshuman Khandual , Alex Van Brunt , Robin Murphy , Thomas Gleixner , Andrew Morton , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Ralph Campbell , hejianet@gmail.com, Kaly Xin , nd@arm.com, Jia He Subject: [PATCH v9 2/3] arm64: mm: implement arch_faults_on_old_pte() on arm64 Date: Wed, 25 Sep 2019 10:59:21 +0800 Message-Id: <20190925025922.176362-3-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190925025922.176362-1-justin.he@arm.com> References: <20190925025922.176362-1-justin.he@arm.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On arm64 without hardware Access Flag, copying fromuser will fail because the pte is old and cannot be marked young. So we always end up with zeroed page after fork() + CoW for pfn mappings. we don't always have a hardware-managed access flag on arm64. Hence implement arch_faults_on_old_pte on arm64 to indicate that it might cause page fault when accessing old pte. Signed-off-by: Jia He Reviewed-by: Catalin Marinas --- arch/arm64/include/asm/pgtable.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index e09760ece844..2b035befb66d 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -868,6 +868,20 @@ static inline void update_mmu_cache(struct vm_area_struct *vma, #define phys_to_ttbr(addr) (addr) #endif +/* + * On arm64 without hardware Access Flag, copying from user will fail because + * the pte is old and cannot be marked young. So we always end up with zeroed + * page after fork() + CoW for pfn mappings. We don't always have a + * hardware-managed access flag on arm64. + */ +static inline bool arch_faults_on_old_pte(void) +{ + WARN_ON(preemptible()); + + return !cpu_has_hw_af(); +} +#define arch_faults_on_old_pte arch_faults_on_old_pte + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_PGTABLE_H */ -- 2.17.1