x86/doublefault/32: Rename doublefault.c to doublefault_32.c

doublefault.c now only contains 32-bit code.  Rename it to
doublefault_32.c.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/Makefile

@@ -100,7 +100,9 @@ obj-$(CONFIG_KEXEC_FILE)	+= kexec-bzimage64.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump_$(BITS).o
 obj-y				+= kprobes/
 obj-$(CONFIG_MODULES)		+= module.o
-obj-$(CONFIG_DOUBLEFAULT)	+= doublefault.o
+ifeq ($(CONFIG_X86_32),y)
+obj-$(CONFIG_DOUBLEFAULT)	+= doublefault_32.o
+endif
 obj-$(CONFIG_KGDB)		+= kgdb.o
 obj-$(CONFIG_VM86)		+= vm86_32.o
 obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o

arch/x86/kernel/doublefault_32.c

@@ -10,8 +10,6 @@
 #include <asm/processor.h>
 #include <asm/desc.h>
 
-#ifdef CONFIG_X86_32
-
 #define DOUBLEFAULT_STACKSIZE (1024)
 static unsigned long doublefault_stack[DOUBLEFAULT_STACKSIZE];
 #define STACK_START (unsigned long)(doublefault_stack+DOUBLEFAULT_STACKSIZE)
@@ -71,5 +69,3 @@ struct x86_hw_tss doublefault_tss __cacheline_aligned = {
 
 	.__cr3		= __pa_nodebug(swapper_pg_dir),
 };
-
-#endif