[S390] Convert memory detection into C code.

Hopefully this will make it more maintainable and less error prone.
Code makes use of search_exception_tables(). Since it calls this
function before the kernel exeception table is sorted, there is an
early call to sort_main_extable().

This way it's easy to use the already present infrastructure of fixup
sections. Also this would allows to easily convert the rest of
head[31|64].S into C code.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/include/asm-s390/processor.h b/include/asm-s390/processor.h
index cf71c54..4c1b739 100644
--- a/include/asm-s390/processor.h
+++ b/include/asm-s390/processor.h
@@ -331,6 +331,18 @@
 }
 
 /*
+ * Basic Machine Check/Program Check Handler.
+ */
+
+extern void s390_base_mcck_handler(void);
+extern void s390_base_pgm_handler(void);
+extern void s390_base_ext_handler(void);
+
+extern void (*s390_base_mcck_handler_fn)(void);
+extern void (*s390_base_pgm_handler_fn)(void);
+extern void (*s390_base_ext_handler_fn)(void);
+
+/*
  * CPU idle notifier chain.
  */
 #define CPU_IDLE	0