Re: [SH][PATCH] Disable ABI frame sniffer

[Daniel Jacobowitz <drow@false.org>]

On Thu, Nov 10, 2005 at 11:59:39PM +0100, Mark Kettenis wrote:
> Ah there's your real problem.  The unwinder walks off the stack and at
> that point concludes the stack is thrashed.  This is a recurring
> problem on many platforms, especially when threads are involved.  It
> might be possible to detect the end of the stack on your platform and
> teach the fallback unwinder about it.  That might involve some changes
> to the threads library and/or crt0 though, to make it mark the end of
> the stack properly.  It'd also be great to have a way to encode the
> end of the stack in CFI.  Unfortunately there has been quite a bit of
> talk about this, but nobody has implemeneted anything yet.

How short your memory... :-)

  http://sources.redhat.com/ml/gdb-patches/2005-03/msg00021.html

There's no way in GCC to annotate a function with this property, and it
appears that the thread-start routine in Andrew's OS is written in C,
so I don't know if it helps.

The fp == 0 and pc == 0 checks are one level off for stopping this, as
I recall.  A cleverer solution to that might be possible.

-- 
Daniel Jacobowitz
CodeSourcery, LLC