ppc64 vDSO update

[Benjamin Herrenschmidt]

 .../...

>  - Added a new export to userland: __kernel_sync_dicache (prototype below) that
>    does the dcache flush / icache invalidate necessary to turn data into executable,
>    I also added the dynamic symbol patching mecanism I wrote about earlier so that
>    the "__kernel_sync_dicache" symbol is automatically modified by the kernel to
>    point to the right version based on the CPU you are running on. At this point,
>    there are 2 implementations, a generic one and a POWER5 one. Ultimately, this
>    mecanism will be used for a lot more "alternatives" once we get more functions
>    in the vDSO, most notably locks.
>  .../...
> 
> I forgot to describe the prototype of that new function, here it is:
> 
> void __kernel_sync_dicache(unsigned long start, unsigned long end)
> 
> Flushes the data cache & invalidate the instruction cache for the
> provided range [start, end[
> 
> Ben.
> 
> 
>