From patchwork Sun Jul 9 08:30:54 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ding Tianhong X-Patchwork-Id: 107236 Delivered-To: patch@linaro.org Received: by 10.140.101.44 with SMTP id t41csp2096948qge; Sun, 9 Jul 2017 01:44:25 -0700 (PDT) X-Received: by 10.84.130.42 with SMTP id 39mr11914737plc.60.1499589864973; Sun, 09 Jul 2017 01:44:24 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1499589864; cv=none; d=google.com; s=arc-20160816; b=uhrVTxcU4OQrTKHhuM0yUp79gvnkFZQyvOoaevhSh/6g5Jx2G2K75SJwZ3LEF+78i/ 5dNTTPCBUbuy/J/C/k3ZhieS60frqVrI3qyVjTqLiMQHiXO6l5i7AopyHs1uJlcJWJUv 5qCSPYDoCMyXcL7n6HbjLiIoWlwWrdEif2l+g+0g2yu2/Sf7omKBfJnmxCIH+GFL+Yfj kHyXW6cup1Iuipo/hVYPYlqTCW7SCDbqr8lBCjM3CH/ULs06hSzoSx33893+/SlDASNE XnPIfHWQU+GQrmRzgcOi/3ku2TopDWxgufMO73CM8qc/IZ04/5BzSncndNSY4VpyiRUs 65Rw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :user-agent:date:message-id:to:subject:from :arc-authentication-results; bh=jI8hGr54ANJi5GTNeC2FHT0qwCpUv1Z/QcnxYdeXzKo=; b=W0L9UkJx87vZFBA59TW14LzgR8+WygLRi0VLjvgki+Ca+LOP4j/t7OBzzSfLoUa4u1 bS0nQn3RC8DIJIY468N9eTcBm4ESxs2vdNOWmc4BDcxwr8v9iPUnM0Q5b24x+bfOzV5N 520G/3uFouvjNBsH0Jq/LCP3wN81SUSnNVb+SeMNDlEkrD1lnWMckAh6dthcCYMgd5Ld TiUg0TebN3R3twq+lCjbwxZxR61IY5+oY5jcCD/gK0crkuZni5KU7vapnSEf5241QpD9 pW7gGJqnhA11hPx3Kkvtw8TJSgeSqhz16AxGOD6WpFqGZAHEmtNJc+A5hYuPLo/puj6k jhXQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id p10si3058947pfj.460.2017.07.09.01.44.24; Sun, 09 Jul 2017 01:44:24 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752039AbdGIIbq (ORCPT + 25 others); Sun, 9 Jul 2017 04:31:46 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:9807 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750859AbdGIIbp (ORCPT ); Sun, 9 Jul 2017 04:31:45 -0400 Received: from 10.3.17.39 (EHLO DGGEML404-HUB.china.huawei.com) ([10.3.17.39]) by dggrg02-dlp.huawei.com (MOS 4.4.6-GA FastPath queued) with ESMTP id AQT14790; Sun, 09 Jul 2017 16:31:10 +0800 (CST) Received: from [127.0.0.1] (10.177.23.32) by DGGEML404-HUB.china.huawei.com (10.3.17.39) with Microsoft SMTP Server id 14.3.301.0; Sun, 9 Jul 2017 16:31:01 +0800 From: Ding Tianhong Subject: [PATCH RESEND] arm64: arch_timer: fix the infinite recursion when enable ftrace and erratum workaround To: Mark Rutland , Marc Zyngier , Catalin Marinas , Will Deacon , LinuxArm , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Message-ID: <321e4c16-aa14-beee-b6dc-36e19e5ec35a@huawei.com> Date: Sun, 9 Jul 2017 16:30:54 +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-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020203.5961E9CE.00F6, 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: 8fe5dbb3e72fafa57868c208cf6da254 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When enable preempt and debug 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 tracing the preempt_disable/enable calls would cause trace_clock() which would get local timer to go into infinite recursion when enable the arch timer erratum workaround for some chips, so Prevent tracing of preempt_disable/enable() in arch_timer_reg_read_stable(). This problem is similar to the fixed by upstream commit 96b3d28bf4 ("sched/clock: Prevent tracing recursion in sched_clock_cpu()"). 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(-) -- 1.9.0 Tested-by: Hanjun Guo Acked-by: Mark Rutland Acked-by: Marc Zyngier 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); \ } \