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Date:	Thu, 27 Jul 2006 10:27:42 -0700
From:	David Daney <ddaney@avtrex.com>
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To:	Thiemo Seufer <ths@networkno.de>
Cc:	Atsushi Nemoto <anemo@mba.ocn.ne.jp>, linux-mips@linux-mips.org,
	ralf@linux-mips.org
Subject: Re: [PATCH] dump_stack() based on prologue code analysis
References: <20060726.232231.59465336.anemo@mba.ocn.ne.jp> <44C8EFE2.4010102@avtrex.com> <20060727170305.GB4505@networkno.de>
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Thiemo Seufer wrote:
> David Daney wrote:
> 
>>Atsushi Nemoto wrote:
>>
>>>Instead of dump all possible address in the stack, unwind the stack
>>>frame based on prologue code analysis, as like as get_chan() does.
>>>While the code analysis might fail for some reason, there is a new
>>>kernel option "raw_show_trace" to disable this feature.
>>>
>>>Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
>>
>>Let me start by saying I have not analyzed how all this code works, but 
>>I have done something similar in user space.
>>
>>Since the kernel ABI does not use gp, many functions may not have a 
>>prolog (especially when compiled with newer versions of GCC).  In the 
>>user space case, most leaf functions have no prolog.  For the kernel I 
>>would imagine that many non-leaf functions (simple non-leaf functions 
>>that do only a tail call) would also not have a prolog.
> 
> 
> Non-leaves have to save/restore $31 somewhere, so there should be a
> prologue.

OK, good point.

But there is still the leaf function problem.

David Daney.