Separate the gdbstub from the debug core

Split the former kernel/kgdb.c into debug_core.c which contains the
kernel debugger exception logic and to the gdbstub.c which contains
the logic for allowing gdb to talk to the debug core.

This also created a private include file called debug_core.h which
contains all the definitions to glue the debug_core to any other
debugger connections.

CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

include/linux/kgdb.h

@@ -264,6 +264,7 @@ extern unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs);
 
 extern int kgdb_register_io_module(struct kgdb_io *local_kgdb_io_ops);
 extern void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops);
+extern struct kgdb_io *dbg_io_ops;
 
 extern int kgdb_hex2long(char **ptr, unsigned long *long_val);
 extern int kgdb_mem2hex(char *mem, char *buf, int count);

kernel/debug/Makefile

@@ -2,5 +2,4 @@
 # Makefile for the linux kernel debugger
 #
 
-obj-$(CONFIG_KGDB) += debug_core.o
-
+obj-$(CONFIG_KGDB) += debug_core.o gdbstub.o