No code changes, just documenting what's happening a little better.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Merge the defines of STACKFRAMESIZE, STK_REG, STK_PARAM from different
places.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Anything that uses a constructed instruction (ie. from ppc-opcode.h),
need to use the new R0 macro, as %r0 is not going to work.

Also convert usages of macros where we are just determining an offset
(usually for a load/store), like:
	std	r14,STK_REG(r14)(r1)
Can't use STK_REG(r14) as %r14 doesn't work in the STK_REG macro since
it's just calculating an offset.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Implement a POWER7 optimised copy_page using VMX and enhanced
prefetch instructions. We use enhanced prefetch hints to prefetch
both the load and store side. We copy a cacheline at a time and
fall back to regular loads and stores if we are unable to use VMX
(eg we are in an interrupt).

The following microbenchmark was used to assess the impact of
the patch:

http://ozlabs.org/~anton/junkcode/page_fault_file.c

We test MAP_PRIVATE page faults across a 1GB file, 100 times:

# time ./page_fault_file -p -l 1G -i 100

Before: 22.25s
After:  18.89s

17% faster
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>