linux-kernel - Re: [PATCH] mips: irq: add statckoverflow detection

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Message-ID: <4C757CF4.6010304@caviumnetworks.com>
Date:	Wed, 25 Aug 2010 13:28:36 -0700
From:	David Daney <ddaney@...iumnetworks.com>
To:	jiang.adam@...il.com
CC:	ralf@...ux-mips.org, dmitri.vorobiev@...ial.com,
	wuzhangjin@...il.com, peterz@...radead.org, fweisbec@...il.com,
	tj@...nel.org, tglx@...utronix.de, mingo@...e.hu,
	linux-mips@...ux-mips.org, linux-kernel@...r.kernel.org
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, jiang.adam@...il.com wrote:
> From: Adam Jiang<jiang.adam@...il.com>
>
> Add stackoverflow detection to mips arch
>
> Signed-off-by: Adam Jiang<jiang.adam@...il.com>
> ---
>   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();

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