From patchwork Wed Sep 25 02:59:21 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jia He X-Patchwork-Id: 11159953 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B4DA61668 for ; Wed, 25 Sep 2019 03:00:19 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8D0D620673 for ; Wed, 25 Sep 2019 03:00:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="V1dxrjqq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8D0D620673 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=G22M87aRwnlmWN1BWI1upYTWzu5GsFw1zS8TxCBMjoU=; b=V1dxrjqq30exCjVrrYW2uk9XDI WLi03sIunRqlJxssvaS7eE5el0csQ+ej9veQI4nqlbFbuie8d8+ZeCe/6FO/R9CuskE7rXxD8AA46 CZQdrscnEa1bq+FRR1xOBsloCGui6tK3P6NJH7jWsIna8k8f7fdc9clk4itmx1Igajmd0RSdaTiQJ q6ZEsdtW8Okdu/keaDio0HwoXZj8U8m6GdQC46iJmDNJcAtInK6wMWREIyptSSL9sIXheBdUa+ysO yCdShcnabdk+CUxafkg6lEAvyDPjoWq+D7x7Wnez+KuVnu3E8lcJo3t89M8hBf4/yftEJJiOn7Nj0 m9h6EYzA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1iCxXO-0001To-Dm; Wed, 25 Sep 2019 03:00:18 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1iCxWs-0008HE-Mq for linux-arm-kernel@lists.infradead.org; Wed, 25 Sep 2019 02:59:48 +0000 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 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-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190924_195946_894958_BED963CC X-CRM114-Status: GOOD ( 10.63 ) X-Spam-Score: 0.0 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (0.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ralph Campbell , Jia He , Anshuman Khandual , Alex Van Brunt , Kaly Xin , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Punit Agrawal , hejianet@gmail.com, Andrew Morton , nd@arm.com, Robin Murphy , Thomas Gleixner MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org 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 */