Please help with the OMAP static mapping mess

[Russell King - ARM Linux]

On Tue, Oct 04, 2011 at 05:10:36PM -0400, Nicolas Pitre wrote:
> Which makes me think... with all those architectures intercepting 
> ioremap calls in order to provide an equivalent static mapping address, 
> they already get an unexpected domain given that static mappings are 
> mostly DOMAIN_IO and not DOMAIN_KERNEL as would result from an non 
> intercepted ioremap call.

That's a necessary evil - otherwise we have to separate out the
ioremap from vmalloc.

Incidentally, how are you dealing with the problem of a static mapping
setting up a L1 page table entry for DOMAIN_IO, and then a vmalloc
request coming in, overlapping that L1 page table?

If this memory then gets accessed with get_user() with set_fs(get_ds()),
the kernel will oops as we don't switch DOMAIN_IO memory on set_fs().
(I don't know if this happens in practice, but there's nothing to say
that it's illegal to do this.)