[PATCH resend] mips: add arch_trigger_all_cpu_backtrace() function

[Eunbong Song]

Currently, arch_trigger_all_cpu_backtrace() is defined in only x86 and sparc which has nmi interrupt.
But in case of softlockup not a hadrlockup, it could be possible to dump backtrace of all cpus.
And this could be helpful for debugging.

for example, if system has 2 cpus.

CPU 0 CPU 1
acquire read_lock()

try to do write_lock()

,,,
missing read_unlock()

In this case, dump_stack() print only backtrace for "CPU 0".
If CPU1's calltrace is printed it's very helpful.

This patch adds arch_trigger_all_cpu_backtrace() for mips architecture.
And this enables when softlockup_all_cpu_backtrace is equalt to 1 and
softlock is occurred to dump all cpu's backtrace.

Signed-off-by: Eunbong Song <***@samsung.com>
---
arch/mips/include/asm/irq.h | 3 +++
arch/mips/kernel/process.c | 18 ++++++++++++++++++
2 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/arch/mips/include/asm/irq.h b/arch/mips/include/asm/irq.h
index 39f07ae..5a4e1bb 100644
--- a/arch/mips/include/asm/irq.h
+++ b/arch/mips/include/asm/irq.h
@@ -48,4 +48,7 @@ extern int cp0_compare_irq;
extern int cp0_compare_irq_shift;
extern int cp0_perfcount_irq;

+void arch_trigger_all_cpu_backtrace(bool);
+#define arch_trigger_all_cpu_backtrace arch_trigger_all_cpu_backtrace
+
#endif /* _ASM_IRQ_H */
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 636b074..5801f21 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -42,6 +42,7 @@
#include <asm/isadep.h>
#include <asm/inst.h>
#include <asm/stacktrace.h>
+#include <asm/irq_regs.h>

#ifdef CONFIG_HOTPLUG_CPU
void arch_cpu_idle_dead(void)
@@ -532,3 +533,20 @@ unsigned long arch_align_stack(unsigned long sp)

return sp & ALMASK;
}
+
+static void arch_dump_stack(void *info)
+{
+ struct pt_regs *regs;
+
+ regs = get_irq_regs();
+
+ if (regs)
+ show_regs(regs);
+
+ dump_stack();
+}
+
+void arch_trigger_all_cpu_backtrace(bool include_self)
+{
+ smp_call_function(arch_dump_