selftests/powerpc: Import Anton's memcpy / copy_tofrom_user tests

Turn Anton's memcpy / copy_tofrom_user test into something that can
live in tools/testing/selftests.

It requires one turd in arch/powerpc/lib/memcpy_64.S, but it's pretty
harmless IMHO.

We are sailing very close to the wind with the feature macros. We define
them to nothing, which currently means we get a few extra nops and
include the unaligned calls.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/lib/memcpy_64.S b/arch/powerpc/lib/memcpy_64.S
index d2bbbc8..72ad055 100644
--- a/arch/powerpc/lib/memcpy_64.S
+++ b/arch/powerpc/lib/memcpy_64.S
@@ -14,7 +14,9 @@
 BEGIN_FTR_SECTION
 	std	r3,48(r1)	/* save destination pointer for return value */
 FTR_SECTION_ELSE
+#ifndef SELFTEST
 	b	memcpy_power7
+#endif
 ALT_FTR_SECTION_END_IFCLR(CPU_FTR_VMX_COPY)
 	PPC_MTOCRF(0x01,r5)
 	cmpldi	cr1,r5,16