Re: [PATCH] dump_stack() based on prologue code analysis

[Nigel Stephens <nigel@mips.com>]

David Daney wrote:
> Atsushi Nemoto wrote:
>> On Thu, 27 Jul 2006 20:12:45 +0100, Thiemo Seufer <ths@networkno.de> 
>> wrote:
>>
>>> IOW, binary analysis can't be expected to provide full accuracy, but
>>> we can live with a reasonable approximation, I think.
>>
>>
>> Yes, this is a starting point.
>>
>> The patch (and current mips get_wchan() implementation) tries to do is
>> what I used to do to analyze stack dump by hand.
>>
>> 1. Determine PC and SP.
>> 2. Disassemble a function containing the PC address.
>> 3. If the function is leaf, make use RA for new PC.
>
> This was always the tricky part for me.  How do you know if the 
> function is a leaf?
>

I think that if you cannot find a store instruction which saves RA to 
the stack -- either because it's a real leaf and there is no such store, 
or because the PC hasn't yet reached the store instruction -- then in 
both cases it can be treated as a leaf.

Nigel