From patchwork Wed Feb 12 11:46:34 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 3637891 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A2C2CBF13A for ; Wed, 12 Feb 2014 12:21:55 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 52D8E201FE for ; Wed, 12 Feb 2014 12:21:54 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E7578201EC for ; Wed, 12 Feb 2014 12:21:52 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WDYon-0007sx-5r; Wed, 12 Feb 2014 12:21:33 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1WDYok-000109-ME; Wed, 12 Feb 2014 12:21:30 +0000 Received: from mezzanine.sirena.org.uk ([2400:8900::f03c:91ff:fedb:4f4]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WDYoi-0000yY-Ar for linux-arm-kernel@lists.infradead.org; Wed, 12 Feb 2014 12:21:29 +0000 Received: from cpc11-sgyl31-2-0-cust68.sgyl.cable.virginm.net ([94.175.92.69] helo=debutante.sirena.org.uk) by mezzanine.sirena.org.uk with esmtpsa (TLS1.2:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.80) (envelope-from ) id 1WDYoE-0008KP-U3; Wed, 12 Feb 2014 12:20:59 +0000 Received: from broonie by debutante.sirena.org.uk with local (Exim 4.82) (envelope-from ) id 1WDYGz-0007bO-Cy; Wed, 12 Feb 2014 11:46:37 +0000 From: Mark Brown To: Catalin Marinas , Will Deacon Date: Wed, 12 Feb 2014 11:46:34 +0000 Message-Id: <1392205594-29186-1-git-send-email-broonie@kernel.org> X-Mailer: git-send-email 1.9.0.rc3 X-SA-Exim-Connect-IP: 94.175.92.69 X-SA-Exim-Mail-From: broonie@sirena.org.uk X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-4.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 Subject: [PATCH] arm64: smp: Add a memory barrier before we start secondary cores X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: Yes (on mezzanine.sirena.org.uk) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140212_072128_752614_0F8E3558 X-CRM114-Status: GOOD ( 11.35 ) X-Spam-Score: -2.6 (--) Cc: linaro-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Mark Brown X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From: Mark Brown Ensure that memory writes will be visible to the newly started core by inserting a write barrier prior to starting. This adds robustness against possible incomplete synchronisation of state. Suggested-by: Catalin Marinas Signed-off-by: Mark Brown --- arch/arm64/kernel/smp.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 9660750f34ba..f5520d8fafab 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -160,6 +160,11 @@ asmlinkage void secondary_start_kernel(void) smp_store_cpu_info(cpu); /* + * Ensure memory writes are visible before we start. + */ + smp_wmb(); + + /* * OK, now it's safe to let the boot CPU continue. Wait for * the CPU migration code to notice that the CPU is online * before we continue.