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=-5.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 36051C2D0DB for ; Sat, 25 Jan 2020 18:06:30 +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 01B6620716 for ; Sat, 25 Jan 2020 18:06:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="W/qRPqlk"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="jDMo/3Cq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 01B6620716 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=armlinux.org.uk 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=dhnXnjbWsXJlKynpYdmbB9YPM+tEJCvb5t+6zXuVrB0=; b=W/qRPqlkQNrDw6 n3dT3FtC8lmyHu6prJ9++CQV/Egb9LW5mVudWs+F0UBAGpJbQDcpFicjvabvtanz5U0sz7TLEHU4C xkMu431w14AFHK0IP9UwotwShU6+3YkaAbK+yFBYJVZK8UlMpa2+NOHmZqnvBYv1xY9mQyjOOKM0M JfGOfcFsSnmPZx/rHYtGyV2AlOqTXgFSz3xEpzWlBZNUF753+NexMgrMFZbPffG4dp8ErEJBwTjlr C7rMHa54eq6l8Lh1+RucE3qBtqw/fW8FO50wd1jf8JhJA8rZ6XxTmXlvF0rHPuhI548tOe9yeLSXG l+2qKJzP9fDnHw+2Pm9g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ivPpE-0001CL-TM; Sat, 25 Jan 2020 18:06:28 +0000 Received: from pandora.armlinux.org.uk ([2001:4d48:ad52:3201:214:fdff:fe10:1be6]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1ivPpB-0001Bj-Bf for linux-arm-kernel@lists.infradead.org; Sat, 25 Jan 2020 18:06:27 +0000 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=NviSb6rLz8itB3Zb7lSO9C2tMpUikxorYtCnHZUsTc4=; b=jDMo/3CqNLZpHfqfiTSusv1fz aqFiFnduaHw6BMQY6r9WwdlhPS3PT6K7uVmdCu60AVOKxOXzKvFpOpcpPRNigphgGJdh3SlXwuXyX U5qlsjKX85/A7Q7zcCWiFqLLFVzyIIazYBwaUFLhhOnrwjkveMkGBWHfxaLiKacfU0jOo1Hkb/SD1 xSg46CISWxBgfmoa90xMmiGGPpqhEbwY5S2oAPCda4kum7rHSL7XFUsfsfdeQKemVlUZmxKzggYsU mbDb3IO5c29Nb7kQ+QgZ6Ln30DfhF3j5+KlSweFJOzGlm17JkAoV59rWb9tj1f1KPQgvRFsxlq9wa +TCjUuucg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:43208) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ivPp1-0006xW-3B; Sat, 25 Jan 2020 18:06:15 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1ivPoz-00084f-Dl; Sat, 25 Jan 2020 18:06:13 +0000 Date: Sat, 25 Jan 2020 18:06:13 +0000 From: Russell King - ARM Linux admin To: Guenter Roeck Subject: Re: [PATCH] ARM: 8936/1: decompressor: avoid CP15 barrier instructions in v7 cache setup code Message-ID: <20200125180613.GR25745@shell.armlinux.org.uk> References: <20200125173950.GA19126@roeck-us.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200125173950.GA19126@roeck-us.net> 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-20200125_100625_574463_CAD71B6C X-CRM114-Status: GOOD ( 16.59 ) 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: Marc Zyngier , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Ard Biesheuvel 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 Sat, Jan 25, 2020 at 09:39:50AM -0800, Guenter Roeck wrote: > Hi, > > On Fri, Nov 08, 2019 at 01:44:32PM +0100, Ard Biesheuvel wrote: > > Commit e17b1af96b2afc38e684aa2f1033387e2ed10029 > > > > "ARM: 8857/1: efi: enable CP15 DMB instructions before cleaning the cache" > > > > added some explicit handling of the CP15BEN bit in the SCTLR system > > register, to ensure that CP15 barrier instructions are enabled, even > > if we enter the decompressor via the EFI stub. > > > > However, as it turns out, there are other ways in which we may end up > > using CP15 barrier instructions without them being enabled. I.e., when > > the decompressor startup code skips the cache_on() initially, we end > > up calling cache_clean_flush() with the caches and MMU off, in which > > case the CP15BEN bit in SCTLR may not be programmed either. And in > > fact, cache_on() itself issues CP15 barrier instructions before actually > > enabling them by programming the new SCTLR value (and issuing an ISB) > > > > Since all these routines are specific to v7, let's clean this up by > > using the ordinary v7 barrier instructions in the v7 specific cache > > handling routines, so that we never rely on the CP15 ones. This also > > avoids the issue where a barrier is required between programming SCTLR > > and using the CP15 barrier instructions, which would result in two > > different kinds of barriers being used in the same function. > > > > Acked-by: Marc Zyngier > > Signed-off-by: Ard Biesheuvel > > Signed-off-by: Russell King > > This patch causes all qemu emulations for ARM1176 to fail hard (stall with > no console output even with earlycon enabled). This affects witherspoon-bmc, > ast2500-evb, romulus-bmc, and swift-bmc. It does not affect emulations > for other CPU types, even with the same kernel configuration (such as > ast2600-evb). Hmm, looks like we're going to have to drop 8936/1, 8941/1 and 8942/1 in that case. -- 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel