Re: Boot failure in 2.5.31 BK with new TLS patch

Gabriel Paubert (paubert@iram.es)
Sat, 17 Aug 2002 20:26:56 +0200


James Bottomley wrote:

>
>
> Actually, the intel manual recommends (but doesn't require) a wierd alignment
> for the descriptors. It recommends aligning them at an address which is 2 MOD
> 4 to avoid possible alignment check faults in user mode. Not that I think we
> can ever run into the problem, but we should probably obey the recommendation.
> I'll fix this up as well.

This is already done for the IDT descriptor, but not (yet) for the gdt
descriptor(s).

Alignment checks are only done when CPL==3. And lidt/lgdt are (obviously)
privileged, although sidt/sgdt (and sldt/str for that matter) are not,
but I can't see how application could take benefit or make malicious use
of this capability.

Gabriel.

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