From patchwork Sun Sep 14 11:57:14 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Thompson X-Patchwork-Id: 4901271 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 578A3BEEA5 for ; Sun, 14 Sep 2014 12:02:06 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 836FF20114 for ; Sun, 14 Sep 2014 12:02:05 +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 A55932020E for ; Sun, 14 Sep 2014 12:02:04 +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 1XT8TT-0005Zo-NL; Sun, 14 Sep 2014 12:00:11 +0000 Received: from mail-we0-f172.google.com ([74.125.82.172]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1XT8T8-00049y-Oj for linux-arm-kernel@lists.infradead.org; Sun, 14 Sep 2014 11:59:51 +0000 Received: by mail-we0-f172.google.com with SMTP id k48so2750526wev.3 for ; Sun, 14 Sep 2014 04:59:28 -0700 (PDT) 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=MWOlSJaxt3du8IqhmP9HgCt3yI4o/voVsQcK6tMOI1Y=; b=AyKhsMHe96qPIO22Cc0O8SPzfud4TkEyHGGDHZPKzoAp0zuaGNw6SqkZeXghmL25QJ VDhZAJkJF6O1NG3GaUoiqv+rUg9irDeXeLmPPIA5QugWfveaFXiMFqcxSHQOLL2mN3M+ du802rTIL3sn7TRsvQGzjs66+5fA+MX6hkDKRANW2kwVMWk+wP6JYKj1lI1pBTPqMbAc t9g+ZbtRwoitMXjyxsZaXT5Oo/CFT8AvJfcAEHWT7IPhlP0xcK9Wob1iQ/wzjG07z+KW ERHt10uZTUZ29SNNiYI4ssR2Seoq5E87YwKDfNxQoMDuck3DGjMHy7Zku+70TWJmJMXC aE0g== X-Gm-Message-State: ALoCoQnzLJ2ivaLGU6pib5HTV49JDfdqvHczG4dhepRApolCZQf5jxnh7MoLbcMnCpKWB+4FXZif X-Received: by 10.180.104.201 with SMTP id gg9mr9027091wib.15.1410695968381; Sun, 14 Sep 2014 04:59:28 -0700 (PDT) Received: from harvey.bri.st.com ([212.183.140.14]) by mx.google.com with ESMTPSA id fh5sm7947027wib.5.2014.09.14.04.59.25 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 14 Sep 2014 04:59:27 -0700 (PDT) From: Daniel Thompson To: Russell King Subject: [PATCH 3.17-rc4 v6 5/6] ARM: add basic support for on-demand backtrace of other CPUs Date: Sun, 14 Sep 2014 12:57:14 +0100 Message-Id: <1410695835-10496-6-git-send-email-daniel.thompson@linaro.org> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1410695835-10496-1-git-send-email-daniel.thompson@linaro.org> References: <1410695835-10496-1-git-send-email-daniel.thompson@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140914_045950_952621_8D153515 X-CRM114-Status: GOOD ( 17.01 ) X-Spam-Score: -0.7 (/) Cc: Daniel Thompson , linaro-kernel@lists.linaro.org, patches@linaro.org, linux-kernel@vger.kernel.org, John Stultz , Russell King , Thomas Gleixner , 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=-2.5 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE, RP_MATCHES_RCVD,UNPARSEABLE_RELAY autolearn=no 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 53c15de..be1d07d 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 9388a3d..94959f9 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; @@ -539,6 +543,21 @@ 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) @@ -618,6 +637,12 @@ 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); @@ -712,3 +737,40 @@ 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(); +}