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=-5.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_MUTT 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 BAE2AC07E85 for ; Fri, 7 Dec 2018 11:55:29 +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 8CBFA20672 for ; Fri, 7 Dec 2018 11:55:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="e7mBd9Ls" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8CBFA20672 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+infradead-linux-arm-kernel=archiver.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:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=w1NYd2YpGpVMnO2h7QZp8zL4uP6X9BfG98X0lXq4WWk=; b=e7mBd9LspCBfy1 iUyjgKt1rEJxxPlfwq565aTKr+G9fVkFx/LkFbBPSFY/Ic0zIJVre+/GRvVipNQGLjnyNnkVzT7ZE UVfHiuwsUvo/oymfa0NtFUMEX64jboj+nXlJRi8Ar1A3ZMkcITp4be9jn30gaMPrk2ALUwRSdve8a muZo/2pTvEL+PSzrJQ5CmxbpZzk4Vk0M8sg9yEtsXWMg7x6kSYXkR+D1oIubBM2xYecJOQ9mrugXa ucgvnk5nyhRJX/Q91J39yqeE9ylkahTLGUb3ya07VUYTrro1Zkr1KrXCnCwp8P103vYLIENTpgcWQ xG0Ad6XrhOedFdEiNIDQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gVEj8-0000BL-Ar; Fri, 07 Dec 2018 11:55:26 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gVEj5-0000Af-GZ for linux-arm-kernel@lists.infradead.org; Fri, 07 Dec 2018 11:55:24 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 003FAEBD; Fri, 7 Dec 2018 03:55:13 -0800 (PST) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.113]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9D7E93F5AF; Fri, 7 Dec 2018 03:55:11 -0800 (PST) Date: Fri, 7 Dec 2018 11:55:09 +0000 From: Catalin Marinas To: Steve Capper Subject: Re: [PATCH V5 6/7] arm64: mm: introduce 52-bit userspace support Message-ID: <20181207115508.GC23085@arrakis.emea.arm.com> References: <20181206225042.11548-1-steve.capper@arm.com> <20181206225042.11548-7-steve.capper@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20181206225042.11548-7-steve.capper@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181207_035523_550548_D16B2518 X-CRM114-Status: GOOD ( 16.28 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: suzuki.poulose@arm.com, jcm@redhat.com, ard.biesheuvel@linaro.org, will.deacon@arm.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Dec 06, 2018 at 10:50:41PM +0000, Steve Capper wrote: > On arm64 there is optional support for a 52-bit virtual address space. > To exploit this one has to be running with a 64KB page size and be > running on hardware that supports this. > > For an arm64 kernel supporting a 48 bit VA with a 64KB page size, > some changes are needed to support a 52-bit userspace: > * TCR_EL1.T0SZ needs to be 12 instead of 16, > * TASK_SIZE needs to reflect the new size. > > This patch implements the above when the support for 52-bit VAs is > detected at early boot time. > > On arm64 userspace addresses translation is controlled by TTBR0_EL1. As > well as userspace, TTBR0_EL1 controls: > * The identity mapping, > * EFI runtime code. > > It is possible to run a kernel with an identity mapping that has a > larger VA size than userspace (and for this case __cpu_set_tcr_t0sz() > would set TCR_EL1.T0SZ as appropriate). However, when the conditions for > 52-bit userspace are met; it is possible to keep TCR_EL1.T0SZ fixed at > 12. Thus in this patch, the TCR_EL1.T0SZ size changing logic is > disabled. > > Signed-off-by: Steve Capper Reviewed-by: Catalin Marinas _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel