s390/mm: Create virtual memory layout structure

This is a preparatory rework to allow uncoupling virtual
and physical addresses spaces.

Put virtual memory layout information into a structure
to improve code generation when accessing the structure
members, which are currently only ident_map_size and
__kaslr_offset.
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

arch/s390/boot/startup.c

@@ -19,7 +19,7 @@
 #include "boot.h"
 #include "uv.h"
 
-unsigned long __bootdata_preserved(__kaslr_offset);
+struct vm_layout __bootdata_preserved(vm_layout);
 unsigned long __bootdata_preserved(__abs_lowcore);
 unsigned long __bootdata_preserved(__memcpy_real_area);
 pte_t *__bootdata_preserved(memcpy_real_ptep);
@@ -30,7 +30,6 @@ unsigned long __bootdata_preserved(vmemmap_size);
 unsigned long __bootdata_preserved(MODULES_VADDR);
 unsigned long __bootdata_preserved(MODULES_END);
 unsigned long __bootdata_preserved(max_mappable);
-unsigned long __bootdata(ident_map_size);
 
 u64 __bootdata_preserved(stfle_fac_list[16]);
 u64 __bootdata_preserved(alt_stfle_fac_list[16]);

arch/s390/include/asm/page.h

@@ -178,7 +178,16 @@ int arch_make_page_accessible(struct page *page);
 #define HAVE_ARCH_MAKE_PAGE_ACCESSIBLE
 #endif
 
-extern unsigned long __kaslr_offset;
+struct vm_layout {
+	unsigned long kaslr_offset;
+	unsigned long identity_size;
+};
+
+extern struct vm_layout vm_layout;
+
+#define __kaslr_offset		vm_layout.kaslr_offset
+#define ident_map_size		vm_layout.identity_size
+
 static inline unsigned long kaslr_offset(void)
 {
 	return __kaslr_offset;

arch/s390/kernel/setup.c

@@ -146,10 +146,9 @@ static u32 __amode31_ref *__ctl_linkage_stack = __ctl_linkage_stack_amode31;
 static u32 __amode31_ref *__ctl_duct = __ctl_duct_amode31;
 
 unsigned long __bootdata_preserved(max_mappable);
-unsigned long __bootdata(ident_map_size);
 struct physmem_info __bootdata(physmem_info);
 
-unsigned long __bootdata_preserved(__kaslr_offset);
+struct vm_layout __bootdata_preserved(vm_layout);
 int __bootdata_preserved(__kaslr_enabled);
 unsigned int __bootdata_preserved(zlib_dfltcc_support);
 EXPORT_SYMBOL(zlib_dfltcc_support);