Sender: root AT delorie DOT com
Message-ID: <3781F878.E2AE32B8@inti.gov.ar>
Date: Tue, 06 Jul 1999 09:37:12 -0300
From: salvador <salvador AT inti DOT gov DOT ar>
Organization: INTI
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To: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
CC: djgpp-workers AT delorie DOT com, Robert Hoehne <robert DOT hoehne AT gmx DOT net>,
        Eric Rudd <rudd AT cyberoptics DOT com>
Subject: Re: .align directives in libc.a
References: <Pine DOT SUN DOT 3 DOT 91 DOT 990704154148 DOT 13333G-100000 AT is>
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Reply-To: djgpp-workers AT delorie DOT com

Eli Zaretskii wrote:

> On Thu, 1 Jul 1999, salvador wrote:
>
> > Can we tell Gas to use "int 3" (or other trap) when pading between functions?
>
> The alignment pseudo-ops allow to define the value of the byte with
> which to pad.  Thus, ".p2align 3,0xcc" should pad to 8-byte boundary
> with Int 3 instructions.
>
> But why is this a good idea?

To trap jumps in this space. Example: you have a corrupted pointer to function and
you jump to the gap between 2 functions. Using nops or things like movl %eax,%eax
you will enter in the next function so you:

1) Will lose information about the problem.
2) Call a function that could be dangerous.

That's all.

SET


--
Salvador Eduardo Tropea (SET). (Electronics Engineer)
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