[kernel] powerpc: Make vmalloc_to_phys() public

[Paul Mackerras]

On Mon, Jan 25, 2016 at 04:46:03PM +1100, Michael Ellerman wrote:
> On Thu, 2016-21-01 at 07:35:08 UTC, Alexey Kardashevskiy wrote:
> > This makes vmalloc_to_phys() public as there will be another user
> > (in-kernel VFIO acceleration) for it soon.
> > 
> > As a part of future little optimization, this changes the helper to call
> > vmalloc_to_pfn() instead of vmalloc_to_page() as the size of the
> > struct page may not be power-of-two aligned which will make gcc use
> > multiply instructions instead of shifts.
> 
> You should also mention why you need to export it, presumably because whatever
> new user you have in mind can be built as a module.

If I remember correctly, it's the *existing* user in hv-24x7.c that
needs the export.

Paul.