[mirror_ubuntu-artful-kernel.git] / lib / nmi_backtrace.c

/*
 *  NMI backtrace support
 *
 * Gratuitously copied from arch/x86/kernel/apic/hw_nmi.c by Russell King,
 * with the following header:
 *
 *  HW NMI watchdog support
 *
 *  started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
 *
 *  Arch specific calls to support NMI watchdog
 *
 *  Bits copied from original nmi.c file
 */
#include <linux/cpumask.h>
#include <linux/delay.h>
#include <linux/kprobes.h>
#include <linux/nmi.h>

#ifdef arch_trigger_all_cpu_backtrace
/* For reliability, we're prepared to waste bits here. */
static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;

/* "in progress" flag of arch_trigger_all_cpu_backtrace */
static unsigned long backtrace_flag;

/*
 * When raise() is called it will be is passed a pointer to the
 * backtrace_mask. Architectures that call nmi_cpu_backtrace()
 * directly from their raise() functions may rely on the mask
 * they are passed being updated as a side effect of this call.
 */
void nmi_trigger_all_cpu_backtrace(bool include_self,
				   void (*raise)(cpumask_t *mask))
{
	int i, this_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(this_cpu, to_cpumask(backtrace_mask));

	if (!cpumask_empty(to_cpumask(backtrace_mask))) {
		pr_info("Sending NMI to %s CPUs:\n",
			(include_self ? "all" : "other"));
		raise(to_cpumask(backtrace_mask));
	}

	/* 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();
	}

	/*
	 * Force flush any remote buffers that might be stuck in IRQ context
	 * and therefore could not run their irq_work.
	 */
	printk_nmi_flush();

	clear_bit_unlock(0, &backtrace_flag);
	put_cpu();
}

bool nmi_cpu_backtrace(struct pt_regs *regs)
{
	int cpu = smp_processor_id();

	if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
		pr_warn("NMI backtrace for cpu %d\n", cpu);
		if (regs)
			show_regs(regs);
		else
			dump_stack();
		cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
		return true;
	}

	return false;
}
NOKPROBE_SYMBOL(nmi_cpu_backtrace);
#endif
Commit	Line	Data
b2c0b2cb RK	1	/*
	2	* NMI backtrace support
	3	*
	4	* Gratuitously copied from arch/x86/kernel/apic/hw_nmi.c by Russell King,
	5	* with the following header:
	6	*
	7	* HW NMI watchdog support
	8	*
	9	* started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
	10	*
	11	* Arch specific calls to support NMI watchdog
	12	*
	13	* Bits copied from original nmi.c file
	14	*/
	15	#include <linux/cpumask.h>
	16	#include <linux/delay.h>
	17	#include <linux/kprobes.h>
	18	#include <linux/nmi.h>
b2c0b2cb RK	19
	20	#ifdef arch_trigger_all_cpu_backtrace
	21	/* For reliability, we're prepared to waste bits here. */
	22	static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
b2c0b2cb RK	23
	24	/* "in progress" flag of arch_trigger_all_cpu_backtrace */
	25	static unsigned long backtrace_flag;
	26
0768330d DT	27	/*
	28	* When raise() is called it will be is passed a pointer to the
	29	* backtrace_mask. Architectures that call nmi_cpu_backtrace()
	30	* directly from their raise() functions may rely on the mask
	31	* they are passed being updated as a side effect of this call.
	32	*/
b2c0b2cb RK	33	void nmi_trigger_all_cpu_backtrace(bool include_self,
	34	void (raise)(cpumask_t mask))
	35	{
42a0bb3f	36	int i, this_cpu = get_cpu();
b2c0b2cb RK	37
	38	if (test_and_set_bit(0, &backtrace_flag)) {
	39	/*
	40	* If there is already a trigger_all_cpu_backtrace() in progress
	41	* (backtrace_flag == 1), don't output double cpu dump infos.
	42	*/
	43	put_cpu();
	44	return;
	45	}
	46
	47	cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
	48	if (!include_self)
	49	cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask));
	50
b2c0b2cb RK	51	if (!cpumask_empty(to_cpumask(backtrace_mask))) {
	52	pr_info("Sending NMI to %s CPUs:\n",
	53	(include_self ? "all" : "other"));
	54	raise(to_cpumask(backtrace_mask));
	55	}
	56
	57	/* Wait for up to 10 seconds for all CPUs to do the backtrace */
	58	for (i = 0; i < 10 * 1000; i++) {
	59	if (cpumask_empty(to_cpumask(backtrace_mask)))
	60	break;
	61	mdelay(1);
	62	touch_softlockup_watchdog();
	63	}
	64
	65	/*
42a0bb3f PM	66	* Force flush any remote buffers that might be stuck in IRQ context
42a0bb3f PM	67	* and therefore could not run their irq_work.
b2c0b2cb	68	*/
42a0bb3f	69	printk_nmi_flush();
b2c0b2cb	70
42a0bb3f	71	clear_bit_unlock(0, &backtrace_flag);
b2c0b2cb RK	72	put_cpu();
	73	}
	74
b2c0b2cb RK	75	bool nmi_cpu_backtrace(struct pt_regs *regs)
	76	{
	77	int cpu = smp_processor_id();
	78
	79	if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
b2c0b2cb	80	pr_warn("NMI backtrace for cpu %d\n", cpu);
0768330d DT	81	if (regs)
	82	show_regs(regs);
	83	else
	84	dump_stack();
b2c0b2cb RK	85	cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
	86	return true;
	87	}
	88
	89	return false;
	90	}
	91	NOKPROBE_SYMBOL(nmi_cpu_backtrace);
	92	#endif