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=-2.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED, USER_AGENT_NEOMUTT autolearn=unavailable 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 0A5D7C10F12 for ; Wed, 17 Apr 2019 10:31:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF7032173C for ; Wed, 17 Apr 2019 10:31:29 +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="zlwxkvKb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731600AbfDQKbN (ORCPT ); Wed, 17 Apr 2019 06:31:13 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:50772 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728575AbfDQKbM (ORCPT ); Wed, 17 Apr 2019 06:31:12 -0400 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=Mlspx2F3hquyjaWbJCFMBJqDbcOeqhgLomei92f1A3Y=; b=zlwxkvKb2XrzTEXnY0P1LO/lt 2sF6JLnyGuXvfpCe0SX7ucnnXsifKSWkYWvB1SlEl6qlX8HTyhY3uCoH6XZwE9SppsuzN7T05XISD JpoMsQV0PJ9vkvRNRCi2L3FBUQuXuNoI0f594pU1HtXk83d2yulRtKFEUqI0SlgJjRlnh4dYEVDc7 MXv8youhQtNvnHJ5u/aY1SiVJ13+4n5t7AqxILPsBwr/2daNZTTcHzutjH3d5Ud7Y6lqW0l+5HTUG pAaq4Hqd2GpG7xcnB5jbcrB7ZicQHY/fGXRim+jZACtmvB+UBFhOGZ2bq8hlZgOvEvZTaq/PA/a+u iHeXNcstw==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:52140) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1hGhqL-00011w-7N; Wed, 17 Apr 2019 11:31:05 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.89) (envelope-from ) id 1hGhqJ-0000mJ-1Z; Wed, 17 Apr 2019 11:31:03 +0100 Date: Wed, 17 Apr 2019 11:31:02 +0100 From: Russell King - ARM Linux admin To: Catalin Marinas Cc: Christoph Hellwig , Heinrich Schuchardt , stable@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Arnd Bergmann Subject: Re: [PATCH 1/1] arm: mm: Export __sync_icache_dcache() for xen-privcmd Message-ID: <20190417103102.rl33skdknnqshcoj@shell.armlinux.org.uk> References: <20190413163052.11407-1-xypron.glpk@gmx.de> <20190415055109.GB9279@infradead.org> <20190417094137.2gkbtinldiwbkvwy@shell.armlinux.org.uk> <20190417100351.oix3df7hwwivgf7k@mbp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190417100351.oix3df7hwwivgf7k@mbp> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 17, 2019 at 11:03:51AM +0100, Catalin Marinas wrote: > On Wed, Apr 17, 2019 at 10:41:37AM +0100, Russell King wrote: > > On Sun, Apr 14, 2019 at 10:51:09PM -0700, Christoph Hellwig wrote: > > > On Sat, Apr 13, 2019 at 06:30:52PM +0200, Heinrich Schuchardt wrote: > > > > This patch avoids > > > > ERROR: "__sync_icache_dcache" [drivers/xen/xen-privcmd.ko] undefined! > > > > observed when compiling v4.19.34. > > > > > > > > The xen-privcmd driver, which can be modular, calls set_pte_at() > > > > which in turn may call __sync_icache_dcache(). > > > > > > Maybe that really is a sign that it should not be modular.. > > > > This issue has been discussed several times, and this URL gives a list > > of all messages on linux-arm-kernel that mention __sync_icache_dcache: > > > > https://archive.armlinux.org.uk/lurker/search/20380101.000000.00000000@ml:linux-arm-kernel,sb:__sync_icache_dcache.en.html > > > > At the beginning of March, Boris Ostrovsky pointed that another solution > > is available that does not need architecture private symbols to be > > exported. > > > > Since I've already said in a previous thread that I don't want this > > function exported, it seems the way forward is pretty obvious. > > Arnd submitted a patch, not sure what happened to it: > > https://lore.kernel.org/lkml/20190304204826.2414365-1-arnd@arndb.de/ Thanks Catalin, this is the "another solution" that I referred to above. (You'll find the exact same URL in Boris' email.) > I think this boils down to whether set_pte_at() is allowed to be called > from loadable modules. If yes, __sync_icache_dcache() needs exporting, > otherwise Arnd's patch makes the relevant code built-in (and, if merged, > I'm happy to revert the similar export on arm64). I think I've clearly expressed my opinion on that. Hence why "the way forward is pretty obvious." I don't understand why we still have the problem. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up