x86: add debug of invalid per_cpu map accesses

dont crash survivable situations.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/asm-x86/topology.h

@@ -70,7 +70,8 @@ static inline int cpu_to_node(int cpu)
 	if (x86_cpu_to_node_map_early_ptr) {
 		printk("KERN_NOTICE cpu_to_node(%d): usage too early!\n",
 			(int)cpu);
-		BUG();
+		dump_stack();
+		return ((int *)x86_cpu_to_node_map_early_ptr)[cpu];
 	}
 #endif
 	if (per_cpu_offset(cpu))