powerpc: Add PPC_NOP_INSTR, a hash define for the preferred nop instruction

A bunch of code has hard-coded the value for a "nop" instruction, it
would be nice to have a #define for it.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/cputable.c

@@ -17,6 +17,7 @@
 #include <linux/module.h>
 
 #include <asm/oprofile_impl.h>
+#include <asm/code-patching.h>
 #include <asm/cputable.h>
 #include <asm/prom.h>		/* for PTRRELOC on ARCH=ppc */
 
@@ -1663,7 +1664,7 @@ void do_feature_fixups(unsigned long value, void *fixup_start, void *fixup_end)
 		pend = ((unsigned int *)fcur) + (fcur->end_off / 4);
 
 		for (p = pstart; p < pend; p++) {
-			*p = 0x60000000u;
+			*p = PPC_NOP_INSTR;
 			asm volatile ("dcbst 0, %0" : : "r" (p));
 		}
 		asm volatile ("sync" : : : "memory");

arch/powerpc/kernel/crash_dump.c

@@ -44,7 +44,7 @@ static void __init create_trampoline(unsigned long addr)
 	 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
 	 * two instructions it doesn't require any registers.
 	 */
-	patch_instruction(p, 0x60000000); /* nop */
+	patch_instruction(p, PPC_NOP_INSTR);
 	patch_branch(++p, addr + PHYSICAL_START, 0);
 }
 

arch/powerpc/kernel/module_64.c

@@ -24,6 +24,7 @@
 #include <asm/module.h>
 #include <asm/uaccess.h>
 #include <asm/firmware.h>
+#include <asm/code-patching.h>
 #include <linux/sort.h>
 
 #include "setup.h"
@@ -330,7 +331,7 @@ static unsigned long stub_for_addr(Elf64_Shdr *sechdrs,
    restore r2. */
 static int restore_r2(u32 *instruction, struct module *me)
 {
-	if (*instruction != 0x60000000) {
+	if (*instruction != PPC_NOP_INSTR) {
 		printk("%s: Expect noop after relocate, got %08x\n",
 		       me->name, *instruction);
 		return 0;

include/asm-powerpc/code-patching.h

@@ -12,6 +12,8 @@
 
 #include <asm/types.h>
 
+#define PPC_NOP_INSTR	0x60000000
+
 /* Flags for create_branch:
  * "b"   == create_branch(addr, target, 0);
  * "ba"  == create_branch(addr, target, BRANCH_ABSOLUTE);