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From: Daniel Thompson <daniel.thompson@linaro.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Daniel Thompson <daniel.thompson@linaro.org>,
	Jason Cooper <jason@lakedaemon.net>,
	Russell King <linux@arm.linux.org.uk>,
	Will Deacon <will.deacon@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Stephen Boyd <sboyd@codeaurora.org>,
	John Stultz <john.stultz@linaro.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, patches@linaro.org,
	linaro-kernel@lists.linaro.org,
	Sumit Semwal <sumit.semwal@linaro.org>,
	Dirk Behme <dirk.behme@de.bosch.com>,
	Daniel Drake <drake@endlessm.com>,
	Dmitry Pervushin <dpervushin@gmail.com>,
	Tim Sander <tim@krieglstein.org>
Subject: [PATCH 3.19-rc2 v15 7/8] ARM: Add support for on-demand backtrace of other CPUs
Date: Fri, 23 Jan 2015 14:22:31 +0000	[thread overview]
Message-ID: <1422022952-31552-8-git-send-email-daniel.thompson@linaro.org> (raw)
In-Reply-To: <1422022952-31552-1-git-send-email-daniel.thompson@linaro.org>

Duplicate the x86 code to trigger a backtrace using an NMI and hook
it up to IPI on ARM. Where it is possible for the hardware to do so the
IPI will be delivered at FIQ level.

Also provided are a few small items of plumbing to hook up the new code.

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Steven Rostedt <rostedt@goodmis.org>
---
 arch/arm/Kconfig               |  1 +
 arch/arm/include/asm/hardirq.h |  2 +-
 arch/arm/include/asm/irq.h     |  5 ++++
 arch/arm/include/asm/smp.h     |  3 ++
 arch/arm/kernel/smp.c          | 68 ++++++++++++++++++++++++++++++++++++++++++
 arch/arm/kernel/traps.c        |  3 ++
 6 files changed, 81 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 97d07ed60a0b..91d62731b52d 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -11,6 +11,7 @@ config ARM
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select ARCH_WANT_IPC_PARSE_VERSION
+	select ARCH_WANT_NMI_PRINTK
 	select BUILDTIME_EXTABLE_SORT if MMU
 	select CLONE_BACKWARDS
 	select CPU_PM if (SUSPEND || CPU_IDLE)
diff --git a/arch/arm/include/asm/hardirq.h b/arch/arm/include/asm/hardirq.h
index fe3ea776dc34..5df33e30ae1b 100644
--- a/arch/arm/include/asm/hardirq.h
+++ b/arch/arm/include/asm/hardirq.h
@@ -5,7 +5,7 @@
 #include <linux/threads.h>
 #include <asm/irq.h>
 
-#define NR_IPI	8
+#define NR_IPI	9
 
 typedef struct {
 	unsigned int __softirq_pending;
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/include/asm/smp.h b/arch/arm/include/asm/smp.h
index 18f5a554134f..b076584ac0fa 100644
--- a/arch/arm/include/asm/smp.h
+++ b/arch/arm/include/asm/smp.h
@@ -18,6 +18,8 @@
 # error "<asm/smp.h> included in non-SMP build"
 #endif
 
+#define SMP_IPI_FIQ_MASK 0x0100
+
 #define raw_smp_processor_id() (current_thread_info()->cpu)
 
 struct seq_file;
@@ -79,6 +81,7 @@ extern void arch_send_call_function_single_ipi(int cpu);
 extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
 extern void arch_send_wakeup_ipi_mask(const struct cpumask *mask);
 
+extern void ipi_cpu_backtrace(struct pt_regs *regs);
 extern int register_ipi_completion(struct completion *completion, int cpu);
 
 struct smp_operations {
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 5e6052e18850..93fe51d305d1 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -26,6 +26,7 @@
 #include <linux/completion.h>
 #include <linux/cpufreq.h>
 #include <linux/irq_work.h>
+#include <linux/seq_buf.h>
 
 #include <linux/atomic.h>
 #include <asm/smp.h>
@@ -72,6 +73,7 @@ enum ipi_msg_type {
 	IPI_CPU_STOP,
 	IPI_IRQ_WORK,
 	IPI_COMPLETION,
+	IPI_CPU_BACKTRACE,
 };
 
 static DECLARE_COMPLETION(cpu_running);
@@ -444,6 +446,7 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = {
 	S(IPI_CPU_STOP, "CPU stop interrupts"),
 	S(IPI_IRQ_WORK, "IRQ work interrupts"),
 	S(IPI_COMPLETION, "completion interrupts"),
+	S(IPI_CPU_BACKTRACE, "backtrace interrupts"),
 };
 
 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
@@ -558,6 +561,8 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
 	unsigned int cpu = smp_processor_id();
 	struct pt_regs *old_regs = set_irq_regs(regs);
 
+	BUILD_BUG_ON(SMP_IPI_FIQ_MASK != BIT(IPI_CPU_BACKTRACE));
+
 	if ((unsigned)ipinr < NR_IPI) {
 		trace_ipi_entry(ipi_types[ipinr]);
 		__inc_irq_stat(cpu, ipi_irqs[ipinr]);
@@ -611,6 +616,12 @@ 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:
 		pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 		        cpu, ipinr);
@@ -705,3 +716,60 @@ static int __init register_cpufreq_notifier(void)
 core_initcall(register_cpufreq_notifier);
 
 #endif
+
+/* For reliability, we're prepared to waste bits here. */
+static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
+static  cpumask_t printtrace_mask;
+
+void arch_trigger_all_cpu_backtrace(bool include_self)
+{
+	int i;
+	int this_cpu = get_cpu();
+
+	if (0 != prepare_nmi_printk(to_cpumask(backtrace_mask))) {
+		/*
+		 * If there is already an nmi printk sequence in
+		 * progress then just give up...
+		 */
+		put_cpu();
+		return;
+	}
+
+	if (!include_self)
+		cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask));
+	cpumask_copy(&printtrace_mask, 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);
+		touch_softlockup_watchdog();
+	}
+
+	complete_nmi_printk(&printtrace_mask);
+	put_cpu();
+}
+
+void ipi_cpu_backtrace(struct pt_regs *regs)
+{
+	int cpu;
+	printk_func_t orig;
+
+	cpu = smp_processor_id();
+
+	if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
+		orig = this_cpu_begin_nmi_printk();
+		pr_warn("FIQ backtrace for cpu %d\n", cpu);
+		show_regs(regs);
+		this_cpu_end_nmi_printk(orig);
+
+		cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
+	}
+}
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index b35e220ae1b1..1836415b8a5c 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -483,6 +483,9 @@ asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
 #ifdef CONFIG_ARM_GIC
 	gic_handle_fiq_ipi();
 #endif
+#ifdef CONFIG_SMP
+	ipi_cpu_backtrace(regs);
+#endif
 
 	nmi_exit();
 
-- 
1.9.3


  parent reply	other threads:[~2015-01-23 14:25 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-23 14:22 [PATCH 3.19-rc2 v15 0/8] irq/arm: Implement arch_trigger_all_cpu_backtrace Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 1/8] irqchip: gic: Optimize locking in gic_raise_softirq Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 2/8] irqchip: gic: Make gic_raise_softirq FIQ-safe Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 3/8] irqchip: gic: Introduce plumbing for IPI FIQ Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 4/8] sched_clock: Avoid deadlock during read from NMI Daniel Thompson
2015-01-24 22:40   ` Thomas Gleixner
2015-01-26 20:28     ` Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 5/8] printk: Simple implementation for NMI backtracing Daniel Thompson
2015-01-24 21:44   ` Thomas Gleixner
2015-01-26 17:21     ` Daniel Thompson
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 6/8] x86/nmi: Use common printk functions Daniel Thompson
2015-01-23 14:22 ` Daniel Thompson [this message]
2015-01-23 14:22 ` [PATCH 3.19-rc2 v15 8/8] ARM: Fix on-demand backtrace triggered by IRQ Daniel Thompson
2015-02-03 19:06 ` [PATCH 3.19-rc6 v16 0/6] irq/arm: Implement arch_trigger_all_cpu_backtrace Daniel Thompson
2015-02-03 19:06   ` [PATCH 3.19-rc6 v16 1/6] irqchip: gic: Optimize locking in gic_raise_softirq Daniel Thompson
2015-02-26 20:31     ` Nicolas Pitre
2015-02-26 21:05       ` Daniel Thompson
2015-02-26 21:33         ` Nicolas Pitre
2015-02-03 19:06   ` [PATCH 3.19-rc6 v16 2/6] irqchip: gic: Make gic_raise_softirq FIQ-safe Daniel Thompson
2015-02-26 20:33     ` Nicolas Pitre
2015-02-03 19:06   ` [PATCH 3.19-rc6 v16 3/6] irqchip: gic: Introduce plumbing for IPI FIQ Daniel Thompson
2015-02-03 19:06   ` [PATCH 3.19-rc6 v16 4/6] printk: Simple implementation for NMI backtracing Daniel Thompson
2015-02-03 19:06   ` [PATCH 3.19-rc6 v16 5/6] x86/nmi: Use common printk functions Daniel Thompson
2015-02-03 19:06   ` [PATCH 3.19-rc6 v16 6/6] ARM: Add support for on-demand backtrace of other CPUs Daniel Thompson
2015-03-04 10:12 ` [PATCH 4.0-rc1 v17 0/6] irq/arm: Implement arch_trigger_all_cpu_backtrace Daniel Thompson
2015-03-04 10:12   ` [PATCH 4.0-rc1 v17 1/6] irqchip: gic: Optimize locking in gic_raise_softirq Daniel Thompson
2015-03-04 10:12   ` [PATCH 4.0-rc1 v17 2/6] irqchip: gic: Make gic_raise_softirq FIQ-safe Daniel Thompson
2015-03-04 10:12   ` [PATCH 4.0-rc1 v17 3/6] irqchip: gic: Introduce plumbing for IPI FIQ Daniel Thompson
2015-03-04 10:12   ` [PATCH 4.0-rc1 v17 4/6] printk: Simple implementation for NMI backtracing Daniel Thompson
2015-03-04 16:13     ` Joe Perches
2015-03-04 16:20       ` Steven Rostedt
2015-03-04 16:33         ` Daniel Thompson
2015-03-04 17:21           ` Joe Perches
2015-03-05 12:11             ` Daniel Thompson
2015-03-04 10:12   ` [PATCH 4.0-rc1 v17 5/6] x86/nmi: Use common printk functions Daniel Thompson
2015-03-05  0:54     ` Ingo Molnar
2015-03-05 12:29       ` Daniel Thompson
2015-03-05 19:46         ` Ingo Molnar
2015-03-06 19:02           ` Daniel Thompson
2015-03-04 10:12   ` [PATCH 4.0-rc1 v17 6/6] ARM: Add support for on-demand backtrace of other CPUs Daniel Thompson
2015-03-12 13:39 ` [PATCH 4.0-rc2 v18 0/6] irq/arm: Implement arch_trigger_all_cpu_backtrace Daniel Thompson
2015-03-12 13:39   ` [PATCH 4.0-rc2 v18 1/6] irqchip: gic: Optimize locking in gic_raise_softirq Daniel Thompson
2015-03-12 13:39   ` [PATCH 4.0-rc2 v18 2/6] irqchip: gic: Make gic_raise_softirq FIQ-safe Daniel Thompson
2015-03-12 13:39   ` [PATCH 4.0-rc2 v18 3/6] irqchip: gic: Introduce plumbing for IPI FIQ Daniel Thompson
2015-03-12 13:39   ` [PATCH 4.0-rc2 v18 4/6] printk: Simple implementation for NMI backtracing Daniel Thompson
2015-03-12 13:39   ` [PATCH 4.0-rc2 v18 5/6] x86/nmi: Use common printk functions Daniel Thompson
2015-03-12 13:39   ` [PATCH 4.0-rc2 v18 6/6] ARM: Add support for on-demand backtrace of other CPUs Daniel Thompson

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