Rep:Re: Rep:Re: Rep:Re: [f-cpu] Stack handling

["Nicolas Boulay" <nicolas.boulay@ifrance.com>]

That's not the point. When i say "stack for code", it's a stack where
you put you're return adresse when you maid a function  call or
something like that. That's not terrific for speed so i prefer having
"some" data stack like you said. 

That's an argument to change calling convention one more time ? ;p

nicO

-----Message d'origine-----
De: Thomas Lavergne <thomas.lavergne@laposte.net>
A: f-cpu@seul.org
Date: 23/07/02
Objet: Re: Rep:Re: Rep:Re: [f-cpu] Stack handling

Nicolas Boulay wrote:
> Stack have a main draw back : it's add a udge dependancies in a single
> poor register (the stack pointer).

For classical code OK, but for well written alogithm you can use more 
than one stack. On a 68000 processor I've written a compiler that use 
two stack and switch each time between, so each push/pop operation was 
directed alternatively in the first and in the second.
You can use as stack as you want.

> 
> For security reason, i have proposed to use 2 stack : one for data,
one
> for code. So buffer overflow will became really hard ! this could be
> usefull for performance, too. But most of the time, the stack will use
> the register bank...
> 

In most case you never have to exec code in the stack so put it in a 
page without execution right and you can't use buffer overflow to 
execute a shellcode.
Case you need execute code in stack was very rare so in this case you 
can make an exception and check your code a lot of time.

Tom


-- 
Thomas Lavergne                       "Le vrai rêveur est celui qui rêve
                                        de l'impossible."  (Elsa
Triolet)
thomas.lavergne@laposte.net
d-12@laposte.net    ICQ:#137121910     http://assoc.wanadoo.fr/thallium/

*************************************************************
To unsubscribe, send an e-mail to majordomo@seul.org with
unsubscribe f-cpu       in the body. http://f-cpu.seul.org/

 
______________________________________________________________________________
ifrance.com, l'email gratuit le plus complet de l'Internet !
vos emails depuis un navigateur, en POP3, sur Minitel, sur le WAP...
http://www.ifrance.com/_reloc/email.emailif


*************************************************************
To unsubscribe, send an e-mail to majordomo@seul.org with
unsubscribe f-cpu       in the body. http://f-cpu.seul.org/