[PATCH v3] mips: irq: add stackoverflow detection

[PATCH v3] mips: irq: add stackoverflow detection

[Adam Jiang]

Add stackoverflow detection to mips arch

This is the 3rd version of the smiple patch. 2K is too big for many
system, so I Modified the warning line by following Ralf's suggestion.

Signed-off-by: Adam Jiang <jiang.adam@gmail.com>
---
 arch/mips/Kconfig.debug             |    7 +++++++
 arch/mips/include/asm/thread_info.h |    2 ++
 arch/mips/kernel/irq.c              |   25 +++++++++++++++++++++++++
 3 files changed, 34 insertions(+), 0 deletions(-)

diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug
index 43dc279..30c58d4 100644
--- a/arch/mips/Kconfig.debug
+++ b/arch/mips/Kconfig.debug
@@ -67,6 +67,13 @@ 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.
+
 config DEBUG_STACK_USAGE
 	bool "Enable stack utilization instrumentation"
 	depends on DEBUG_KERNEL
diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h
index 70df9c0..b60b28d 100644
--- a/arch/mips/include/asm/thread_info.h
+++ b/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
diff --git a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c
index c6345f5..b43edb7 100644
--- a/arch/mips/kernel/irq.c
+++ b/arch/mips/kernel/irq.c
@@ -151,6 +151,28 @@ void __init init_IRQ(void)
 #endif
 }
 
+#ifdef CONFIG_DEBUG_STACKOVERFLOW
+static inline void check_stack_overflow(void)
+{
+	unsigned long sp;
+
+	asm volatile("move %0, $sp" : "=r" (sp));
+	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 +181,9 @@ 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();
-- 
1.7.2.2

Re: [PATCH v3] mips: irq: add stackoverflow detection

[Sergei Shtylyov]

Hello.

On 06-10-2010 14:41, Adam Jiang wrote:

> Add stackoverflow detection to mips arch

    There's no such word: stackoverflow. Space is needed.

> This is the 3rd version of the smiple patch. 2K is too big for many
> system, so I Modified the warning line by following Ralf's suggestion.

> Signed-off-by: Adam Jiang<jiang.adam@gmail.com>
[...]

> diff --git a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c
> index c6345f5..b43edb7 100644
> --- a/arch/mips/kernel/irq.c
> +++ b/arch/mips/kernel/irq.c
> @@ -151,6 +151,28 @@ void __init init_IRQ(void)
>   #endif
>   }
>
> +#ifdef CONFIG_DEBUG_STACKOVERFLOW
> +static inline void check_stack_overflow(void)
> +{
> +	unsigned long sp;
> +
> +	asm volatile("move %0, $sp" : "=r" (sp));
> +	sp = sp & THREAD_MASK;

    Why not:

	sp &= THREAD_MASK;

    It's C, after all! :-)

WBR, Sergei

Re: [PATCH v3] mips: irq: add stackoverflow detection

[Ralf Baechle]

On Wed, Oct 06, 2010 at 02:53:43PM +0400, Sergei Shtylyov wrote:

> >Add stackoverflow detection to mips arch
> 
>    There's no such word: stackoverflow. Space is needed.
> 
> >This is the 3rd version of the smiple patch. 2K is too big for many
> >system, so I Modified the warning line by following Ralf's suggestion.
> 
> >Signed-off-by: Adam Jiang<jiang.adam@gmail.com>
> [...]
> 
> >diff --git a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c
> >index c6345f5..b43edb7 100644
> >--- a/arch/mips/kernel/irq.c
> >+++ b/arch/mips/kernel/irq.c
> >@@ -151,6 +151,28 @@ void __init init_IRQ(void)
> >  #endif
> >  }
> >
> >+#ifdef CONFIG_DEBUG_STACKOVERFLOW
> >+static inline void check_stack_overflow(void)
> >+{
> >+	unsigned long sp;
> >+
> >+	asm volatile("move %0, $sp" : "=r" (sp));
> >+	sp = sp & THREAD_MASK;
> 
>    Why not:
> 
> 	sp &= THREAD_MASK;
> 
>    It's C, after all! :-)

I already had accepted his previous version with minor changes so I've
combined the two.

Thanks Adam!

  Ralf

Re: [PATCH v3] mips: irq: add stackoverflow detection

[Adam Jiang]

On Wed, Oct 06, 2010 at 12:21:15PM +0100, Ralf Baechle wrote:
> On Wed, Oct 06, 2010 at 02:53:43PM +0400, Sergei Shtylyov wrote:
> 
> > >Add stackoverflow detection to mips arch
> > 
> >    There's no such word: stackoverflow. Space is needed.
> > 
> > >This is the 3rd version of the smiple patch. 2K is too big for many
> > >system, so I Modified the warning line by following Ralf's suggestion.
> > 
> > >Signed-off-by: Adam Jiang<jiang.adam@gmail.com>
> > [...]
> > 
> > >diff --git a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c
> > >index c6345f5..b43edb7 100644
> > >--- a/arch/mips/kernel/irq.c
> > >+++ b/arch/mips/kernel/irq.c
> > >@@ -151,6 +151,28 @@ void __init init_IRQ(void)
> > >  #endif
> > >  }
> > >
> > >+#ifdef CONFIG_DEBUG_STACKOVERFLOW
> > >+static inline void check_stack_overflow(void)
> > >+{
> > >+	unsigned long sp;
> > >+
> > >+	asm volatile("move %0, $sp" : "=r" (sp));
> > >+	sp = sp & THREAD_MASK;
> > 
> >    Why not:
> > 
> > 	sp &= THREAD_MASK;
> > 
> >    It's C, after all! :-)
> 
> I already had accepted his previous version with minor changes so I've
> combined the two.

Thanks Ralf. I am very glad I can do this small piece of code for Linux
kernel, though with many faults. :) No doubt I will try to do much more
then.

Best regards,
/Adam