Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 75b05852 authored by Rohit Vaswani's avatar Rohit Vaswani
Browse files

ARM64: smp: implement arch_trigger_all_cpus_backtrace using IPI 



Since ARM64 doesn't have an NMI, send an IPI to all other CPUs
(current cpu prints the stack directly) to capture a backtrace.

Change-Id: Ib90494123205b3bbaa0b244ccde6c7e40a560199
Signed-off-by: default avatarRohit Vaswani <rvaswani@codeaurora.org>
parent 8e30be93

arch/arm64/include/asm/hardirq.h

+1 −1
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ 
#include <linux/threads.h>

#include <asm/irq.h>



#define NR_IPI	6

#define NR_IPI	7



typedef struct {

	unsigned int __softirq_pending;

arch/arm64/include/asm/irq.h

+3 −0
Original line number Diff line number Diff line
@@ -7,4 +7,7 @@ extern void (*handle_arch_irq)(struct pt_regs *); 
extern void migrate_irqs(void);

extern void set_handle_irq(void (*handle_irq)(struct pt_regs *));



void arch_trigger_all_cpu_backtrace(void);

#define arch_trigger_all_cpu_backtrace arch_trigger_all_cpu_backtrace



#endif

arch/arm64/kernel/smp.c

+72 −0
Original line number Diff line number Diff line
@@ -64,6 +64,7 @@ enum ipi_msg_type { 
	IPI_CPU_STOP,

	IPI_TIMER,

	IPI_WAKEUP,

	IPI_CPU_BACKTRACE,

};



/*
@@ -478,6 +479,7 @@ static const char *ipi_types[NR_IPI] = { 
	S(IPI_CPU_STOP, "CPU stop interrupts"),

	S(IPI_TIMER, "Timer broadcast interrupts"),

	S(IPI_WAKEUP, "CPU wakeup interrupts"),

	S(IPI_CPU_BACKTRACE, "CPU backtrace"),

};



void show_ipi_list(struct seq_file *p, int prec)
@@ -529,6 +531,72 @@ static void ipi_cpu_stop(unsigned int cpu) 
		cpu_relax();

}



static cpumask_t backtrace_mask;

static DEFINE_RAW_SPINLOCK(backtrace_lock);



/* "in progress" flag of arch_trigger_all_cpu_backtrace */

static unsigned long backtrace_flag;



static void smp_send_all_cpu_backtrace(void)

{

	unsigned int this_cpu = smp_processor_id();

	int i;



	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.

		 */

		return;



	cpumask_copy(&backtrace_mask, cpu_online_mask);

	cpu_clear(this_cpu, backtrace_mask);



	pr_info("Backtrace for cpu %d (current):\n", this_cpu);

	dump_stack();



	pr_info("\nsending IPI to all other CPUs:\n");

	if (!cpus_empty(backtrace_mask))

		smp_cross_call(&backtrace_mask, IPI_CPU_BACKTRACE);



	/* Wait for up to 10 seconds for all other CPUs to do the backtrace */

	for (i = 0; i < 10 * 1000; i++) {

		if (cpumask_empty(&backtrace_mask))

			break;

		mdelay(1);

	}



	clear_bit(0, &backtrace_flag);

	smp_mb__after_clear_bit();

}



/*

 * ipi_cpu_backtrace - handle IPI from smp_send_all_cpu_backtrace()

 */

static void ipi_cpu_backtrace(unsigned int cpu, struct pt_regs *regs)

{

	if (cpu_isset(cpu, backtrace_mask)) {

		raw_spin_lock(&backtrace_lock);

		pr_warn("IPI backtrace for cpu %d\n", cpu);

		show_regs(regs);

		raw_spin_unlock(&backtrace_lock);

		cpu_clear(cpu, backtrace_mask);

	}

}



#ifdef CONFIG_SMP

void arch_trigger_all_cpu_backtrace(void)

{

	smp_send_all_cpu_backtrace();

}

#else

void arch_trigger_all_cpu_backtrace(void)

{

	dump_stack();

}

#endif





/*

 * Main handler for inter-processor interrupts

 */
@@ -573,6 +641,10 @@ void handle_IPI(int ipinr, struct pt_regs *regs) 
	case IPI_WAKEUP:

		break;



	case IPI_CPU_BACKTRACE:

		ipi_cpu_backtrace(cpu, regs);

		break;



	default:

		pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);

		break;