From patchwork Fri Nov 14 12:35:42 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Thompson X-Patchwork-Id: 5305801 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id AAA7B9FBB9 for ; Fri, 14 Nov 2014 12:50:16 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C202720145 for ; Fri, 14 Nov 2014 12:50:15 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (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 D5B5E2015D for ; Fri, 14 Nov 2014 12:50:14 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1XpGIG-0004q1-A4; Fri, 14 Nov 2014 12:48:04 +0000 Received: from mail-wi0-f178.google.com ([209.85.212.178]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1XpG6w-0008DJ-Eh for linux-arm-kernel@lists.infradead.org; Fri, 14 Nov 2014 12:36:23 +0000 Received: by mail-wi0-f178.google.com with SMTP id bs8so2542594wib.5 for ; Fri, 14 Nov 2014 04:36:04 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=CDEbxUPYcfoC2H7IXpSXnfHHmM7/4dBLZReZ9wEbX5E=; b=AS9KbpNL44MDyakoKuBUqf4Jca7fVTy3187cSQCjkEGLrnU9+yrRvzgHKY6xiB7Aph kGI0Y/peL4HOaiZtXVDvaK3j7zENEGQ6gCnH425YnTh7XnBvCziov7L/TthFeK4PyRUO 8Gw5Zl9bEx4Yiwl8qd80qMKHU65a6WDq2jAUIcEGMK72P+eZbjNXk1nU9PXr2e+zNz13 FhziFOYDQLbit9dln0jc3uCNfvFc4jJhDBEpJlnUO3b+uwXpeSisNgox/FAMVQayusX3 blHvreGINH8kds2xz2TP8s8Xt2LHptBhxgu1/qI22kz2wVa56TKh3aGqbBEtKL7MO9VM Zmrg== X-Gm-Message-State: ALoCoQmg0+3SyISzmopUKD9wttqiJcNpepbRMHIu7ve5z6Ed0144MDq6cXDg6Dse3ffnFHDfS0Vp X-Received: by 10.180.36.170 with SMTP id r10mr7240585wij.56.1415968563946; Fri, 14 Nov 2014 04:36:03 -0800 (PST) Received: from sundance.lan (cpc4-aztw19-0-0-cust157.18-1.cable.virginm.net. [82.33.25.158]) by mx.google.com with ESMTPSA id j17sm25733441wjn.32.2014.11.14.04.36.02 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 14 Nov 2014 04:36:03 -0800 (PST) From: Daniel Thompson To: Thomas Gleixner , Jason Cooper Subject: [PATCH 3.18-rc3 v8 3/4] ARM: add basic support for on-demand backtrace of other CPUs Date: Fri, 14 Nov 2014 12:35:42 +0000 Message-Id: <1415968543-29469-4-git-send-email-daniel.thompson@linaro.org> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1415968543-29469-1-git-send-email-daniel.thompson@linaro.org> References: <1415183260-6389-1-git-send-email-daniel.thompson@linaro.org> <1415968543-29469-1-git-send-email-daniel.thompson@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20141114_043622_643420_7CAAD212 X-CRM114-Status: GOOD ( 16.07 ) X-Spam-Score: -0.7 (/) Cc: Daniel Thompson , linaro-kernel@lists.linaro.org, Russell King , patches@linaro.org, linux-kernel@vger.kernel.org, Daniel Drake , Dmitry Pervushin , Dirk Behme , John Stultz , Russell King , Sumit Semwal , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 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-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_LOW, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add basic infrastructure for triggering a backtrace of other CPUs via an IPI, preferably at FIQ level. It is intended that this shall be used for cases where we have detected that something has already failed in the kernel. Signed-off-by: Russell King Signed-off-by: Daniel Thompson --- arch/arm/include/asm/irq.h | 5 ++++ arch/arm/kernel/smp.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 67 insertions(+) diff --git a/arch/arm/include/asm/irq.h b/arch/arm/include/asm/irq.h index 53c15dec7af6..be1d07d59ee9 100644 --- a/arch/arm/include/asm/irq.h +++ b/arch/arm/include/asm/irq.h @@ -35,6 +35,11 @@ extern void (*handle_arch_irq)(struct pt_regs *); extern void set_handle_irq(void (*handle_irq)(struct pt_regs *)); #endif +#ifdef CONFIG_SMP +extern void arch_trigger_all_cpu_backtrace(bool); +#define arch_trigger_all_cpu_backtrace(x) arch_trigger_all_cpu_backtrace(x) +#endif + #endif #endif diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 13396d3d600e..14c594a12bef 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -72,8 +72,12 @@ enum ipi_msg_type { IPI_CPU_STOP, IPI_IRQ_WORK, IPI_COMPLETION, + IPI_CPU_BACKTRACE, }; +/* For reliability, we're prepared to waste bits here. */ +static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly; + static DECLARE_COMPLETION(cpu_running); static struct smp_operations smp_ops; @@ -535,6 +539,21 @@ static void ipi_cpu_stop(unsigned int cpu) cpu_relax(); } +static void ipi_cpu_backtrace(struct pt_regs *regs) +{ + int cpu = smp_processor_id(); + + if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) { + static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED; + + arch_spin_lock(&lock); + printk(KERN_WARNING "FIQ backtrace for cpu %d\n", cpu); + show_regs(regs); + arch_spin_unlock(&lock); + cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); + } +} + static DEFINE_PER_CPU(struct completion *, cpu_completion); int register_ipi_completion(struct completion *completion, int cpu) @@ -614,6 +633,12 @@ void handle_IPI(int ipinr, struct pt_regs *regs) irq_exit(); break; + case IPI_CPU_BACKTRACE: + irq_enter(); + ipi_cpu_backtrace(regs); + irq_exit(); + break; + default: printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr); @@ -708,3 +733,40 @@ static int __init register_cpufreq_notifier(void) core_initcall(register_cpufreq_notifier); #endif + +void arch_trigger_all_cpu_backtrace(bool include_self) +{ + static unsigned long backtrace_flag; + int i, cpu = get_cpu(); + + if (test_and_set_bit(0, &backtrace_flag)) { + /* + * If there is already a trigger_all_cpu_backtrace() in progress + * (backtrace_flag == 1), don't output double cpu dump infos. + */ + put_cpu(); + return; + } + + cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask); + if (!include_self) + cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); + + if (!cpumask_empty(to_cpumask(backtrace_mask))) { + pr_info("Sending FIQ to %s CPUs:\n", + (include_self ? "all" : "other")); + smp_cross_call(to_cpumask(backtrace_mask), IPI_CPU_BACKTRACE); + } + + /* Wait for up to 10 seconds for all CPUs to do the backtrace */ + for (i = 0; i < 10 * 1000; i++) { + if (cpumask_empty(to_cpumask(backtrace_mask))) + break; + + mdelay(1); + } + + clear_bit(0, &backtrace_flag); + smp_mb__after_atomic(); + put_cpu(); +}