Subject: Re: Non executable mappings and compatibility options bugs
To: Chuck Silvers <>
From: Emmanuel Dreyfus <>
List: tech-kern
Date: 06/21/2004 00:11:25
Chuck Silvers <> wrote:

> oh...  you're looking at this as a per-process flag, I was thinking it
> would be a per-emulation flag.  having it be per-process would work too.
> but it occurs to me that the problem is a little different than I was
> thinking.  in order to faithfully emulate the behaviour of another OS
> we'll need to know exactly in which cases that OS maps things executable
> when they "should" be non-executable.  I would guess that it probably
> goes beyond just what's going on during execve(), and that usually
> we'll find that an OS that doesn't do everything correctly will be
> making *all* mappings executable, even mmap() mappings without PROT_EXEC.
> so in this case, the vmcmd_* functions are too high-level... we would
> really want to change the behaviour of pmap_enter().  so on powerpc,
> this would mean that if the per-process flag is set then we'll just
> never set the SR_NOEXEC flag in the hardware.

But this problem also exist if we have a per-emulation flag, right?
Emmanuel Dreyfus
Il y a 10 sortes de personnes dans le monde: ceux qui comprennent 
le binaire et ceux qui ne le comprennent pas.