powerpc: Define and use PPC64_ELF_ABI_v2/v1

We're approaching 20 locations where we need to check for ELF ABI v2.
That's fine, except the logic is a bit awkward, because we have to check
that _CALL_ELF is defined and then what its value is.

So check it once in asm/types.h and define PPC64_ELF_ABI_v2 when ELF ABI
v2 is detected.

We also have a few places where what we're really trying to check is
that we are using the 64-bit v1 ABI, ie. function descriptors. So also
add a #define for that, which simplifies several checks.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h
index 994c60a..2015b07 100644
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h
@@ -49,8 +49,7 @@
 
 static inline unsigned long ppc_function_entry(void *func)
 {
-#if defined(CONFIG_PPC64)
-#if defined(_CALL_ELF) && _CALL_ELF == 2
+#ifdef PPC64_ELF_ABI_v2
 	u32 *insn = func;
 
 	/*
@@ -75,14 +74,13 @@
 		return (unsigned long)(insn + 2);
 	else
 		return (unsigned long)func;
-#else
+#elif defined(PPC64_ELF_ABI_v1)
 	/*
 	 * On PPC64 ABIv1 the function pointer actually points to the
 	 * function's descriptor. The first entry in the descriptor is the
 	 * address of the function text.
 	 */
 	return ((func_descr_t *)func)->entry;
-#endif
 #else
 	return (unsigned long)func;
 #endif
@@ -90,7 +88,7 @@
 
 static inline unsigned long ppc_global_function_entry(void *func)
 {
-#if defined(CONFIG_PPC64) && defined(_CALL_ELF) && _CALL_ELF == 2
+#ifdef PPC64_ELF_ABI_v2
 	/* PPC64 ABIv2 the global entry point is at the address */
 	return (unsigned long)func;
 #else
@@ -106,7 +104,7 @@
  */
 
 /* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
-#if defined(_CALL_ELF) && _CALL_ELF == 2
+#ifdef PPC64_ELF_ABI_v2
 #define R2_STACK_OFFSET         24
 #else
 #define R2_STACK_OFFSET         40