From patchwork Thu Jul 6 12:49:33 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ding Tianhong X-Patchwork-Id: 9828219 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id E33F8602BD for ; Thu, 6 Jul 2017 12:50:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D31A728408 for ; Thu, 6 Jul 2017 12:50:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C72DB28517; Thu, 6 Jul 2017 12:50:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 05EA128408 for ; Thu, 6 Jul 2017 12:50:34 +0000 (UTC) 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:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Date:Message-ID:Subject: From:To:Reply-To:Cc:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=GqAftPaWL+/xZ+dKXspcVOuyIyAYhxZYtQ+ZT49MbW4=; b=Xwzj7EDTfpqyJ6 FcOOaRxfWFXa7jwAGU/svLIvbqv5olQHqma+ldgoqyYnSkQ1iwpQMN9el51I2lStDvoLg5HgD7VnE EJNQPlemYVZavpFt1hEqKag/qRXlJSFnlN+NJ4flPW/GNS5x2/ww9aP9OGr7o0R4Xvr6E6agDBcT8 6fhLGAeAbtm9ut7lr09sTuKPOn657x1WekBeYRNDAaQ7caUghVYRvKZ+yPiY3+hKFyAakX5RARNPp qg2KH/LZuwiqz5nn/FwB/L4P/X5GPZUoe1/f/AJtbRjkdfEQdu/4ysZlcWCSFNLf6PGFRmMTOP/2M 5+mmMnCTgjgew+z7+ItQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1dT6Eq-00026w-RG; Thu, 06 Jul 2017 12:50:32 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1dT6En-0000qQ-32 for linux-arm-kernel@lists.infradead.org; Thu, 06 Jul 2017 12:50:31 +0000 Received: from 172.30.72.53 (EHLO DGGEML401-HUB.china.huawei.com) ([172.30.72.53]) by dggrg02-dlp.huawei.com (MOS 4.4.6-GA FastPath queued) with ESMTP id AQP66841; Thu, 06 Jul 2017 20:49:44 +0800 (CST) Received: from [127.0.0.1] (10.177.23.32) by DGGEML401-HUB.china.huawei.com (10.3.17.32) with Microsoft SMTP Server id 14.3.301.0; Thu, 6 Jul 2017 20:49:35 +0800 To: Mark Rutland , Marc Zyngier , Catalin Marinas , Will Deacon , LinuxArm , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" From: Ding Tianhong Subject: [PATCH] arm64: arch_timer: fix the infinite recursion when enable ftrace and erratum workaround Message-ID: <43ec809d-b8f2-eb73-8ad6-9966cf67625f@huawei.com> Date: Thu, 6 Jul 2017 20:49:33 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 X-Originating-IP: [10.177.23.32] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A090205.595E31EA.0056, ss=1, re=0.000, recu=0.000, reip=0.000, cl=1, cld=1, fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 9f2e7ae7b4ecd2ce895e24230727116b X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170706_055029_545577_1DAB2FAF X-CRM114-Status: GOOD ( 10.20 ) 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: , 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 When enable preempt and ftrace, and perform the following steps, the system will hang: mount -t debugfs nodev /sys/kernel/debug/ cd /sys/kernel/debug/tracing/ echo function_graph > current_tracer This is because the preempt_disable and preempt_enable calls would cause infinite recursion for some chips which needs the timer erratum workaround and the system will hang, so use the preempt_disable/enable_notrace calls to prevent recursion. Fixes: 6acc71ccac71 ("arm64: arch_timer: Allows a CPU-specific erratum to only affect a subset of CPUs") Signed-off-by: Ding Tianhong --- arch/arm64/include/asm/arch_timer.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h index 74d08e4..67bb7a4 100644 --- a/arch/arm64/include/asm/arch_timer.h +++ b/arch/arm64/include/asm/arch_timer.h @@ -65,13 +65,13 @@ struct arch_timer_erratum_workaround { u64 _val; \ if (needs_unstable_timer_counter_workaround()) { \ const struct arch_timer_erratum_workaround *wa; \ - preempt_disable(); \ + preempt_disable_notrace(); \ wa = __this_cpu_read(timer_unstable_counter_workaround); \ if (wa && wa->read_##reg) \ _val = wa->read_##reg(); \ else \ _val = read_sysreg(reg); \ - preempt_enable(); \ + preempt_enable_notrace(); \ } else { \ _val = read_sysreg(reg); \ } \