user-mode stack size & location

user-mode stack size & location

[Clemens Kolbitsch]

hi!
i'm working on a new concept of i386 memory management and have to change 
quite a bit of the linux mm. could someone please point out, where the 
location & size of the USER-MODE stack is set for a new program (i.e. after 
calling sys_execve...) exactly?

I know that all settings are simply copied from the parent-process when 
invoking fork and how the stack grows (through page-faults).

However,

1.) is

  mm->start_stack

set inside the

  search_binary_handler / the individual fs-handlers?

i see that the aout-, elf-, etc. handlers all set this variable --> is this 
the only location where it can be set?

2.) when looking at /proc/PID/maps, i see that the stack always ends at 
different locations (obviously close to TASK_SIZE). thus the sizes seem to 
vary. where are they set / where are the infos written to the vma's / the 
PGD?

any help would be greatly appreciated!!
greets,
  clemens

Re: user-mode stack size & location

[Arjan van de Ven]

On Tue, 28 Aug 2007 18:25:01 +0200
Clemens Kolbitsch <clemens.kol@gmx.at> wrote:
> i see that the aout-, elf-, etc. handlers all set this variable -->
> is this the only location where it can be set?
> 
> 2.) when looking at /proc/PID/maps, i see that the stack always ends
> at different locations (obviously close to TASK_SIZE). thus the sizes
> seem to vary. where are they set / where are the infos written to the
> vma's / the PGD?
> 
> any help would be greatly appreciated!!
\

hi,

if you look where arch_align_stack() gets called.. that's where you
want to look. arch_align_stack() gets invoked in code that selects
userspace stack pointers....

Greetings,
   Arjan van de Ven

Re: user-mode stack size & location

[Clemens Kolbitsch]

> hi,
>
> if you look where arch_align_stack() gets called.. that's where you
> want to look. arch_align_stack() gets invoked in code that selects
> userspace stack pointers....
>
> Greetings,
>    Arjan van de Ven

thanks a lot!!