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SubjectRe: [PATCH 1 / ...] i386 dynamic fixup/self modifying code
Hi!


> > > 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. 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). 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

Aha, making a list and just patching early at boot is even simpler
than method I was thinking about.... Why not do it that way?
Pavel
--
Casualities in World Trade Center: ~3k dead inside the building,
cryptography in U.S.A. and free speech in Czech Republic.
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