selftests/powerpc/64: Test all paths through copy routines

The hand-coded assembler 64-bit copy routines include feature sections
that select one code path or another depending on which CPU we are
executing on.  The self-tests for these copy routines end up testing
just one path.  This adds a mechanism for selecting any desired code
path at compile time, and makes 2 or 3 versions of each test, each
using a different code path, so as to cover all the possible paths.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
[mpe: Add -mcpu=power4 to CFLAGS for older compilers]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/powerpc/copyloops/asm/ppc_asm.h

@@ -43,17 +43,16 @@ FUNC_START(enter_vmx_ops)
 FUNC_START(exit_vmx_ops)
 	blr
 
-FUNC_START(memcpy_power7)
-	blr
-
-FUNC_START(__copy_tofrom_user_power7)
-	blr
-
 FUNC_START(__copy_tofrom_user_base)
 	blr
 
-#define BEGIN_FTR_SECTION
-#define FTR_SECTION_ELSE
-#define ALT_FTR_SECTION_END_IFCLR(x)
-#define ALT_FTR_SECTION_END(x, y)
-#define END_FTR_SECTION_IFCLR(x)
+#define BEGIN_FTR_SECTION		.if test_feature
+#define FTR_SECTION_ELSE		.else
+#define ALT_FTR_SECTION_END_IFCLR(x)	.endif
+#define ALT_FTR_SECTION_END_IFSET(x)	.endif
+#define ALT_FTR_SECTION_END(x, y)	.endif
+#define END_FTR_SECTION_IFCLR(x)	.endif
+#define END_FTR_SECTION_IFSET(x)	.endif
+
+/* Default to taking the first of any alternative feature sections */
+test_feature = 1