1 files changed, 64 insertions, 4 deletions

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index a8e32aaf0383..d6e6b5bfd100 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -72,6 +72,7 @@ enum ipi_msg_type {
 	IPI_CPU_STOP,
 	IPI_IRQ_WORK,
 	IPI_COMPLETION,
+	IPI_CPU_BACKTRACE,
 };
 
 static DECLARE_COMPLETION(cpu_running);
@@ -86,9 +87,11 @@ void __init smp_set_ops(struct smp_operations *ops)
 
 static unsigned long get_arch_pgd(pgd_t *pgd)
 {
-	phys_addr_t pgdir = virt_to_idmap(pgd);
-	BUG_ON(pgdir & ARCH_PGD_MASK);
-	return pgdir >> ARCH_PGD_SHIFT;
+#ifdef CONFIG_ARM_LPAE
+	return __phys_to_pfn(virt_to_phys(pgd));
+#else
+	return virt_to_phys(pgd);
+#endif
 }
 
 int __cpu_up(unsigned int cpu, struct task_struct *idle)
@@ -108,7 +111,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
 #endif
 
 #ifdef CONFIG_MMU
-	secondary_data.pgdir = get_arch_pgd(idmap_pgd);
+	secondary_data.pgdir = virt_to_phys(idmap_pgd);
 	secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
 #endif
 	sync_cache_w(&secondary_data);
@@ -456,6 +459,7 @@ 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, "CPU backtrace"),
 };
 
 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
@@ -557,6 +561,58 @@ static void ipi_complete(unsigned int cpu)
 	complete(per_cpu(cpu_completion, cpu));
 }
 
+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;
+
+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");
+	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 (cpu_isset(cpu, backtrace_mask)) {
+		raw_spin_lock(&backtrace_lock);
+		pr_warning("IPI backtrace for cpu %d\n", cpu);
+		show_regs(regs);
+		raw_spin_unlock(&backtrace_lock);
+		cpu_clear(cpu, backtrace_mask);
+	}
+}
+
 /*
  * Main handler for inter-processor interrupts
  */
@@ -623,6 +679,10 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
 		irq_exit();
 		break;
 
+	case IPI_CPU_BACKTRACE:
+		ipi_cpu_backtrace(cpu, regs);
+		break;
+
 	default:
 		printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
 		       cpu, ipinr);