s390/mm: align swapper_pg_dir to 16k

The segment/region table that is part of the kernel image must be
properly aligned to 16k in order to make the crdte inline assembly
work.
Otherwise it will calculate a wrong segment/region table start address
and access incorrect memory locations if the swapper_pg_dir is not
aligned to 16k.

Therefore define BSS_FIRST_SECTIONS in order to put the swapper_pg_dir
at the beginning of the bss section and also align the bss section to
16k just like other architectures did.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/vmlinux.lds.S

@@ -4,6 +4,13 @@
 
 #include <asm/thread_info.h>
 #include <asm/page.h>
+
+/*
+ * Put .bss..swapper_pg_dir as the first thing in .bss. This will
+ * make sure it has 16k alignment.
+ */
+#define BSS_FIRST_SECTIONS *(.bss..swapper_pg_dir)
+
 #include <asm-generic/vmlinux.lds.h>
 
 OUTPUT_FORMAT("elf64-s390", "elf64-s390", "elf64-s390")
@@ -81,7 +88,7 @@ SECTIONS
 	. = ALIGN(PAGE_SIZE);
 	__init_end = .;		/* freed after init ends here */
 
-	BSS_SECTION(0, 2, 0)
+	BSS_SECTION(PAGE_SIZE, 4 * PAGE_SIZE, PAGE_SIZE)
 
 	_end = . ;