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=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 3ADE6C55178 for ; Fri, 23 Oct 2020 10:13:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BEE66208B6 for ; Fri, 23 Oct 2020 10:13:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="bb/ID+nt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S461984AbgJWKNF (ORCPT ); Fri, 23 Oct 2020 06:13:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46112 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S461951AbgJWKND (ORCPT ); Fri, 23 Oct 2020 06:13:03 -0400 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A535C0613CE for ; Fri, 23 Oct 2020 03:13:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Etqkj2bfKGrEGoasEHlQF8c/aYVNaOVt7ntOYQjQy0U=; b=bb/ID+nt/J/pIMZmWsDKIuo9f jylxYWY6FzN4XPAxXyJTeSC6OgQs6+fzpVejDl1UozSPJSvSI8UKdW3pVUtRljaVybV4biSqDKMJ/ JVTTaJk1IZknFfdMjEqGs3zD07xjeaJump4i1INPvETbcPy75j5Xh8AHgL6Uh16FaX3+YXxpg7EDU LnC4K8cohqxa40H7oWEqfG6MdtQElFWfiIM6z5m+3tZgWL1MJpmQ9a3bkNA8zfeENLphhDC0F9/gm 8wpGlzFsijAwLCcZDGP7LUW5tbgvZkj9X0mkr5WRjRCJYMVrwS5jOgDxu3XGHAqKZeB7OTuSji26m DgThbypDg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:49922) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kVu4A-0003HE-Qn; Fri, 23 Oct 2020 11:12:58 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1kVu4A-0008MK-4j; Fri, 23 Oct 2020 11:12:58 +0100 Date: Fri, 23 Oct 2020 11:12:58 +0100 From: Russell King - ARM Linux admin To: Miles Chen Cc: Catalin Marinas , Minchan Kim , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com, Suren Baghdasaryan Subject: Re: [PATCH v2 4/4] arm: replace vector mem type with read-only type Message-ID: <20201023101257.GZ1551@shell.armlinux.org.uk> References: <20201023091437.8225-1-miles.chen@mediatek.com> <20201023091437.8225-5-miles.chen@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201023091437.8225-5-miles.chen@mediatek.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King - ARM Linux admin Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 23, 2020 at 05:14:37PM +0800, Miles Chen wrote: > Since kernel no longer writes to the vector, try to replace > the vector mem type with read-only type and remove L_PTE_MT_VECTORS. > > from Catalin in [1]: > " > > I don't think this matters since the kernel no longer writes to the > > vectors page at run-time but it needs cleaning up a bit (and testing in > > case I missed something). IOW, do we still need a dedicated mapping type > > for the vectors or we can simply use the read-only user page attributes? > " Catalin is incorrect. If CONFIG_KUSER_HELPERS is enabled, then the vectors page is definitely written to - it's a user interface, so it's not going to change: #ifdef CONFIG_KUSER_HELPERS /* * User space must never try to access this * directly. Expect your app to break * eventually if you do so. The user helper * at 0xffff0fe0 must be used instead. (see * entry-armv.S for details) */ *((unsigned int *)0xffff0ff0) = val; #endif -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!