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

To: David Daney <ddaney@avtrex.com>
Subject: Re: [PATCH] dump_stack() based on prologue code analysis
From: Thiemo Seufer <ths@networkno.de>
Date: Thu, 27 Jul 2006 18:03:05 +0100
Cc: Atsushi Nemoto <anemo@mba.ocn.ne.jp>, linux-mips@linux-mips.org, ralf@linux-mips.org
In-reply-to: <44C8EFE2.4010102@avtrex.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20060726.232231.59465336.anemo@mba.ocn.ne.jp> <44C8EFE2.4010102@avtrex.com>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.12-2006-07-14
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.


Thiemo

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