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>

arch/powerpc/kernel/entry_64.S

@@ -453,7 +453,7 @@ _GLOBAL(ret_from_kernel_thread)
 	REST_NVGPRS(r1)
 	mtlr	r14
 	mr	r3,r15
-#if defined(_CALL_ELF) && _CALL_ELF == 2
+#ifdef PPC64_ELF_ABI_v2
 	mr	r12,r14
 #endif
 	blrl

arch/powerpc/kernel/ftrace.c

@@ -608,7 +608,7 @@ unsigned long __init arch_syscall_addr(int nr)
 }
 #endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_PPC64 */
 
-#if defined(CONFIG_PPC64) && (!defined(_CALL_ELF) || _CALL_ELF != 2)
+#ifdef PPC64_ELF_ABI_v1
 char *arch_ftrace_match_adjust(char *str, const char *search)
 {
 	if (str[0] == '.' && search[0] != '.')
@@ -616,4 +616,4 @@ char *arch_ftrace_match_adjust(char *str, const char *search)
 	else
 		return str;
 }
-#endif /* defined(CONFIG_PPC64) && (!defined(_CALL_ELF) || _CALL_ELF != 2) */
+#endif /* PPC64_ELF_ABI_v1 */

arch/powerpc/kernel/head_64.S

@@ -401,7 +401,7 @@ generic_secondary_common_init:
 	ld	r12,CPU_SPEC_RESTORE(r23)
 	cmpdi	0,r12,0
 	beq	3f
-#if !defined(_CALL_ELF) || _CALL_ELF != 2
+#ifdef PPC64_ELF_ABI_v1
 	ld	r12,0(r12)
 #endif
 	mtctr	r12

arch/powerpc/kernel/kprobes.c

@@ -506,12 +506,10 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 
 	/* setup return addr to the jprobe handler routine */
 	regs->nip = arch_deref_entry_point(jp->entry);
-#ifdef CONFIG_PPC64
-#if defined(_CALL_ELF) && _CALL_ELF == 2
+#ifdef PPC64_ELF_ABI_v2
 	regs->gpr[12] = (unsigned long)jp->entry;
-#else
+#elif defined(PPC64_ELF_ABI_v1)
 	regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);
-#endif
 #endif
 
 	return 1;

arch/powerpc/kernel/misc_64.S

@@ -661,7 +661,7 @@ _GLOBAL(kexec_sequence)
 
 #ifndef CONFIG_PPC_BOOK3E
 	/* clear out hardware hash page table and tlb */
-#if !defined(_CALL_ELF) || _CALL_ELF != 2
+#ifdef PPC64_ELF_ABI_v1
 	ld	r12,0(r27)		/* deref function descriptor */
 #else
 	mr	r12,r27

arch/powerpc/kernel/module_64.c

@@ -41,7 +41,7 @@
    this, and makes other things simpler.  Anton?
    --RR.  */
 
-#if defined(_CALL_ELF) && _CALL_ELF == 2
+#ifdef PPC64_ELF_ABI_v2
 
 /* An address is simply the address of the function. */
 typedef unsigned long func_desc_t;
@@ -132,7 +132,7 @@ static u32 ppc64_stub_insns[] = {
 	/* Save current r2 value in magic place on the stack. */
 	0xf8410000|R2_STACK_OFFSET,	/* std     r2,R2_STACK_OFFSET(r1) */
 	0xe98b0020,			/* ld      r12,32(r11) */
-#if !defined(_CALL_ELF) || _CALL_ELF != 2
+#ifdef PPC64_ELF_ABI_v1
 	/* Set up new r2 from function descriptor */
 	0xe84b0028,			/* ld      r2,40(r11) */
 #endif