Merge commit 'a88f9e27498afaea615ad3e93af4f26df1f84987' into after-upstream-android
[linux-3.10.git] / arch / arm / kernel / smp.c
index b36a386..be08596 100644 (file)
@@ -67,6 +67,7 @@ enum ipi_msg_type {
        IPI_CALL_FUNC,
        IPI_CALL_FUNC_SINGLE,
        IPI_CPU_STOP,
+       IPI_CPU_BACKTRACE,
 };
 
 static DECLARE_COMPLETION(cpu_running);
@@ -464,6 +465,7 @@ static const char *ipi_types[NR_IPI] = {
        S(IPI_CALL_FUNC, "Function call interrupts"),
        S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
        S(IPI_CPU_STOP, "CPU stop interrupts"),
+       S(IPI_CPU_BACKTRACE, "CPU backtrace"),
 };
 
 void show_ipi_list(struct seq_file *p, int prec)
@@ -589,6 +591,58 @@ 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;
+
+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_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_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
  */
@@ -639,6 +693,10 @@ 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);