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Message-ID: <4C2B543E.2010309@windriver.com>
Date:   Wed, 30 Jun 2010 07:27:10 -0700
From:   Phil Staub <phils@windriver.com>
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Organization: Wind River Systems
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To:     Adam Jiang <jiang.adam@gmail.com>
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Subject: Re: How to detect STACKOVEFLOW on mips
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On 06/29/2010 10:59 PM, Adam Jiang wrote:
> Hello, list.
>
> I'm having a problem with kernel mode stack on my box. It seems that
> STACKOVERFLOW happened to Linux kernel. However, I can't prove it
> because the lack of any detection in __do_IRQ() function just like on
> the other architectures. If you know something about, please help me
> on following two questions.
> - Is there any possible to do this on MIPS?

The mechanisms I know about for detecting stack overflow include:

1. Use of the MMU - stack ends at a page boundary, adjacent page is
either unmapped or mapped read-only and causes an exception if violated.

2. Hooks inserted into toolchain to cause any stack decrement to be
first tested against a limit.

3. Fill entire stack with a recognizable pattern before first
use. After suspected stack overflow, check to see if the pattern has
been disturbed in the area of the stack limit.

(Disclaimer: I've used all of these in some form on other OSes, but
not on Linux. Someone else may have a more directly relevant answer.)

> - or, more simple question, how could I get the address $sp pointed by
> asm() notation in C?

How about something like:

{
	long x;
	...
	asm("move %0,$29":"=g"(x));
	...
}

Phil

>
> Any suggestion from you will be appreciated.
>
> Best regards,
> /Adam
>
>


-- 
Phil Staub, Senior Member of Technical Staff, Wind River
Direct: 702.290.0470 Fax: 702.982.0085