2010-08-21 06:29:01

by Adam Jiang

Subject: [PATCH] mips: irq: add statckoverflow detection

From: Adam Jiang <[email protected]>

Add stackoverflow detection to mips arch

Signed-off-by: Adam Jiang <[email protected]>
---
arch/mips/Kconfig.debug | 7 +++++++
arch/mips/kernel/irq.c | 19 +++++++++++++++++++
2 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug
index 43dc279..f1a00a2 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/kernel/irq.c b/arch/mips/kernel/irq.c
index c6345f5..6334037 100644
--- a/arch/mips/kernel/irq.c
+++ b/arch/mips/kernel/irq.c
@@ -151,6 +151,22 @@ void __init init_IRQ(void)
#endif
}

+static inline void check_stack_overflow(void)
+{
+#ifdef CONFIG_DEBUG_STACKOVERFLOW
+ long sp;
+
+ asm volatile("move %0, $sp" : "=r" (sp));
+ sp = sp & (THREAD_SIZE-1);
+
+ /* check for stack overflow: is there less then 2KB free? */
+ if (unlikely(sp < (sizeof(struct thread_info) + 2048))) {
+ printk("do_IRQ: stack overflow: %ld\n",
+ sp - sizeof(struct thread_info));
+ dump_stack();
+ }
+#endif
+}
/*
* do_IRQ handles all normal device IRQ's (the special
* SMP cross-CPU interrupts have their own specific
@@ -159,6 +175,9 @@ 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();
--
1.7.1

2010-08-21 13:10:04

by Sergei Shtylyov

Subject: Re: [PATCH] mips: irq: add statckoverflow detection

Hello.

[email protected] wrote:

> From: Adam Jiang <[email protected]>

> Add stackoverflow detection to mips arch

> Signed-off-by: Adam Jiang <[email protected]>
[...]
> diff --git a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c
> index c6345f5..6334037 100644
> --- a/arch/mips/kernel/irq.c
> +++ b/arch/mips/kernel/irq.c
> @@ -151,6 +151,22 @@ void __init init_IRQ(void)
> #endif
> }
>
> +static inline void check_stack_overflow(void)
> +{
> +#ifdef CONFIG_DEBUG_STACKOVERFLOW

#ifdef within function is considered bad style. Better do it this way:

#ifdef CONFIG_DEBUG_STACKOVERFLOW
static inline void check_stack_overflow(void)
{
[...]
}
#else
static inline void check_stack_overflow(void) {}
#endif

> + long sp;
> +
> + asm volatile("move %0, $sp" : "=r" (sp));
> + sp = sp & (THREAD_SIZE-1);
> +
> + /* check for stack overflow: is there less then 2KB free? */

Hm, 2KB seems pretty large margin...

WBR, Sergei

2010-08-25 20:28:45

by David Daney

Subject: Re: [PATCH] mips: irq: add statckoverflow detection

It looks like this patch only checks when processing an interrupt, which
doesn't seem like it would give much coverage.

Am I missing something?

David Daney


On 08/20/2010 11:31 PM, [email protected] wrote:
> From: Adam Jiang<[email protected]>
>
> Add stackoverflow detection to mips arch
>
> Signed-off-by: Adam Jiang<[email protected]>
> ---
> arch/mips/Kconfig.debug | 7 +++++++
> arch/mips/kernel/irq.c | 19 +++++++++++++++++++
> 2 files changed, 26 insertions(+), 0 deletions(-)
>
> diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug
> index 43dc279..f1a00a2 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/kernel/irq.c b/arch/mips/kernel/irq.c
> index c6345f5..6334037 100644
> --- a/arch/mips/kernel/irq.c
> +++ b/arch/mips/kernel/irq.c
> @@ -151,6 +151,22 @@ void __init init_IRQ(void)
> #endif
> }
>
> +static inline void check_stack_overflow(void)
> +{
> +#ifdef CONFIG_DEBUG_STACKOVERFLOW
> + long sp;
> +
> + asm volatile("move %0, $sp" : "=r" (sp));
> + sp = sp& (THREAD_SIZE-1);
> +
> + /* check for stack overflow: is there less then 2KB free? */
> + if (unlikely(sp< (sizeof(struct thread_info) + 2048))) {
> + printk("do_IRQ: stack overflow: %ld\n",
> + sp - sizeof(struct thread_info));
> + dump_stack();
> + }
> +#endif
> +}
> /*
> * do_IRQ handles all normal device IRQ's (the special
> * SMP cross-CPU interrupts have their own specific
> @@ -159,6 +175,9 @@ 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();