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ARM: smp: implement arch_trigger_all_cpus_backtrace using IPI

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Based on a rough patch by frank.rowand@am.sony.com

Since ARM doesn't have an NMI (fiq's are not always available),
send an IPI to all other CPUs (current cpu prints the stack directly)
to capture a backtrace.

Change-Id: I8b163c8cec05d521b433ae133795865e8a33d4e2
Signed-off-by: Dima Zavin <dima@android.com>
This commit is contained in:
Dima Zavin
2011-10-18 16:59:54 -07:00
committed by Colin Cross
parent 74b6cdd957
commit b64f7cc09e
5 changed files with 76 additions and 1 deletions
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58
arch/arm/kernel/smp.c
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@@ -56,6 +56,7 @@ enum ipi_msg_type {
IPI_CALL_FUNC,
IPI_CALL_FUNC_SINGLE,
IPI_CPU_STOP,
IPI_CPU_BACKTRACE,
};
static DECLARE_COMPLETION(cpu_running);
@@ -383,6 +384,7 @@ 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)
@@ -518,6 +520,58 @@ 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
*/
@@ -563,6 +617,10 @@ 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);