KDB support for x86_64?

[Peter Wainwright]

On Sun, 2006-03-26 at 17:32 -0800, Jack Vogel wrote:
> On Mon, Mar 27, 2006 at 08:00:46AM +1000, Nigel Cunningham wrote:
> > Hi.
> > On Sunday 26 March 2006 21:58, Peter Wainwright wrote:
> > > Is KDB still maintained for the x86_64 architecture? oss.sgi.com has
> > > x86_64 patches for kernel 2.6.14 but not for more recent
> > > kernels. I tried to forward-port it to 2.6.16 myself but it is
> > > not giving a proper backtrace (%rsp seems to be wrong at breakpoints).
> > >
> > > Peter Wainwright
> > 
> > I would find it useful too. I've forward ported it as well, and also have the 
> > same backtrace problem. I guess it's probably simple to fix, but it doesn't 
> > irk me enough that I've bothered to try to fix it.
> > 
> > Regards,
> > 
> > Nigel
> 
> Did you have the problem with the last patch, there was 
> some backtrace changes that I accepted that I did not have
> time to test. It would be useful if you could check a before
> and after of that code.
> 
> Regards,
> 
> Jack

Sometime recently the following change occurred in
arch/x86_64/kernel/traps.c:

-       set_system_gate(3,&int3);
+       set_system_gate_ist(3,&int3,DEBUG_STACK); /* int3 can be called
from all */

The int3 handler now runs in a special interrupt stack using
the "long-mode interrupt-stack table".
So calculating the process %rsp from the address of the pt_regs
structure no longer works. How to figure out the address of the
original stack is something I haven't figured out yet because I
have no time to read the fine "AMD64 Architecture Programmer's Manual".

Peter


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