lkml.org 
[lkml]   [2002]   [Aug]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 1 / ...] i386 dynamic fixup/self modifying code
From
Date
On Fri, 2002-08-30 at 01:19, Alan Cox wrote:
> On Wed, 2002-08-28 at 13:11, Pavel Machek wrote:
> > > Unfortunately with this patch executing invalid code will cause the
> > > processor to enter an infinite exception loop rather than panic. Fixing
> > > this is not trivial for SMP+preempt so it's not done at the moment.
> >
> > Using 0xcc for everything should fix that, right?
>
> Except you can't do the fixup on SMP without risking hitting the CPU
> errata.
Worked around by making sure all other processors are stopped (iret is
serializing) sending IPIs if they are not already spinning on the fixup
lock. See patch #2.

> You also break debugging tools that map kernel code pages r/o
> and people who ROM it.
>
> The latter aren't a big problem (they can compile without runtime
> fixups).
OK, I'll add a config option for this.

> For the other fixups though you -have- to do them before you
> run the code. That isnt hard (eg sparc btfixup). You generate a list of
> the addresses in a segment, patch them all and let the init freeup blow
> the table away
Is doing them at runtime with the aforementioned workaround fine?

[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2005-03-22 13:28    [W:0.097 / U:0.356 seconds]
©2003-2014 Jasper Spaans. Advertise on this site