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Commit be186fdf authored by Rohit Vaswani's avatar Rohit Vaswani Committed by Jeevan Shriram
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>
Signed-off-by: default avatarSatya Durga Srinivasu Prabhala <satyap@codeaurora.org>
[kyan: trivial merge conflict resolution & compilation fixes]
Signed-off-by: default avatarKyle Yan <kyan@codeaurora.org>
Signed-off-by: default avatarJeevan Shriram <jshriram@codeaurora.org>
parent daf24777

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
@@ -56,5 +56,8 @@ static inline bool on_irq_stack(unsigned long sp, int cpu) 
	return (low <= sp && sp <= high);

}



void arch_trigger_all_cpu_backtrace(void);

#define arch_trigger_all_cpu_backtrace arch_trigger_all_cpu_backtrace



#endif /* !__ASSEMBLER__ */

#endif

arch/arm64/kernel/smp.c

+73 −1
Original line number Diff line number Diff line
@@ -73,7 +73,8 @@ enum ipi_msg_type { 
	IPI_CPU_STOP,

	IPI_TIMER,

	IPI_IRQ_WORK,

	IPI_WAKEUP

	IPI_WAKEUP,

	IPI_CPU_BACKTRACE,

};



#ifdef CONFIG_ARM64_VHE
@@ -760,6 +761,7 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = { 
	S(IPI_TIMER, "Timer broadcast interrupts"),

	S(IPI_IRQ_WORK, "IRQ work interrupts"),

	S(IPI_WAKEUP, "CPU wake-up interrupts"),

	S(IPI_CPU_BACKTRACE, "CPU backtrace"),

};



static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
@@ -846,6 +848,72 @@ static void ipi_cpu_stop(unsigned int cpu, struct pt_regs *regs) 
		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);

	cpumask_clear_cpu(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 (!cpumask_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_atomic();

}



/*

 * ipi_cpu_backtrace - handle IPI from smp_send_all_cpu_backtrace()

 */

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

{

	if (cpumask_test_cpu(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);

		cpumask_clear_cpu(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

 */
@@ -900,6 +968,10 @@ void handle_IPI(int ipinr, struct pt_regs *regs) 
		break;

#endif



	case IPI_CPU_BACKTRACE:

		ipi_cpu_backtrace(cpu, regs);

		break;



	default:

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

		break;

include/linux/nmi.h

+14 −2
Original line number Diff line number Diff line
@@ -41,25 +41,37 @@ static inline void hardlockup_detector_disable(void) {} 
#ifdef arch_trigger_cpumask_backtrace

static inline bool trigger_all_cpu_backtrace(void)

{

	#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)

		arch_trigger_all_cpu_backtrace();

	else

		arch_trigger_cpumask_backtrace(cpu_online_mask, false);

	#endif



	return true;

}



static inline bool trigger_allbutself_cpu_backtrace(void)

{

	#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)

		arch_trigger_all_cpu_backtrace();

	else

		arch_trigger_cpumask_backtrace(cpu_online_mask, true);

	#endif



	return true;

}



static inline bool trigger_cpumask_backtrace(struct cpumask *mask)

{

	arch_trigger_cpumask_backtrace(mask, false);



	return true;

}



static inline bool trigger_single_cpu_backtrace(int cpu)

{

	arch_trigger_cpumask_backtrace(cpumask_of(cpu), false);



	return true;

}