MIPS: IRQ: Add stackoverflow detection

Add stackoverflow detection to mips arch
Signed-off-by: Adam Jiang <jiang.adam@gmail.com>
Cc: dmitri.vorobiev@movial.com
Cc: wuzhangjin@gmail.com
Cc: ddaney@caviumnetworks.com
Cc: peterz@infradead.org
Cc: fweisbec@gmail.com
Cc: tj@kernel.org
Cc: tglx@linutronix.de
Cc: mingo@elte.hu
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/1559/
Patchwork: https://patchwork.linux-mips.org/patch/1651/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig.debug

@@ -67,6 +67,15 @@ config CMDLINE_OVERRIDE
 
 	  Normally, you will choose 'N' here.
 
+config DEBUG_STACKOVERFLOW
+	bool "Check for stack overflows"
+	depends on DEBUG_KERNEL
+	help
+	  This option will cause messages to be printed if free stack space
+	  drops below a certain limit(2GB on MIPS). The debugging option
+	  provides another way to check stack overflow happened on kernel mode
+	  stack usually caused by nested interruption.
+
 config DEBUG_STACK_USAGE
 	bool "Enable stack utilization instrumentation"
 	depends on DEBUG_KERNEL

arch/mips/include/asm/thread_info.h

@@ -83,6 +83,8 @@ register struct thread_info *__current_thread_info __asm__("$28");
 #define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)
 #define THREAD_MASK (THREAD_SIZE - 1UL)
 
+#define STACK_WARN	(THREAD_SIZE / 8)
+
 #define __HAVE_ARCH_THREAD_INFO_ALLOCATOR
 
 #ifdef CONFIG_DEBUG_STACK_USAGE

arch/mips/kernel/irq.c

@@ -151,6 +151,29 @@ void __init init_IRQ(void)
 #endif
 }
 
+#ifdef DEBUG_STACKOVERFLOW
+static inline void check_stack_overflow(void)
+{
+	unsigned long sp;
+
+	__asm__ __volatile__("move %0, $sp" : "=r" (sp));
+	sp &= THREAD_MASK;
+
+	/*
+	 * Check for stack overflow: is there less than STACK_WARN free?
+	 * STACK_WARN is defined as 1/8 of THREAD_SIZE by default.
+	 */
+	if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
+		printk("do_IRQ: stack overflow: %ld\n",
+		       sp - sizeof(struct thread_info));
+		dump_stack();
+	}
+}
+#else
+static inline void check_stack_overflow(void) {}
+#endif
+
+
 /*
  * do_IRQ handles all normal device IRQ's (the special
  * SMP cross-CPU interrupts have their own specific
@@ -159,6 +182,7 @@ void __init init_IRQ(void)
 void __irq_entry do_IRQ(unsigned int irq)
 {
 	irq_enter();
+	check_stack_overflow();
 	__DO_IRQ_SMTC_HOOK(irq);
 	generic_handle_irq(irq);
 	irq_exit();