s390/vdso: move data page before code pages

For consistency with x86 and arm64 move the data page before code
pages. Similar to commit 601255ae ("arm64: vdso: move data page
before code pages").
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/kernel/vdso.c

@@ -74,7 +74,8 @@ early_initcall(vdso_getcpu_init); /* Must be called before SMP init */
 
 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 {
-	unsigned long addr, vdso_text_start, vdso_text_len, vdso_mapping_len;
+	unsigned long vdso_text_len, vdso_mapping_len;
+	unsigned long vvar_start, vdso_text_start;
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	int rc;
@@ -85,25 +86,24 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 		return -EINTR;
 	vdso_text_len = vdso_pages << PAGE_SHIFT;
 	vdso_mapping_len = vdso_text_len + PAGE_SIZE;
-	addr = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
-	rc = addr;
-	if (IS_ERR_VALUE(addr))
+	vvar_start = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
+	rc = vvar_start;
+	if (IS_ERR_VALUE(vvar_start))
 		goto out;
+	vma = _install_special_mapping(mm, vvar_start, PAGE_SIZE,
+				       VM_READ|VM_MAYREAD|VM_PFNMAP,
+				       &vvar_mapping);
+	rc = PTR_ERR(vma);
+	if (IS_ERR(vma))
+		goto out;
+	vdso_text_start = vvar_start + PAGE_SIZE;
 	/* VM_MAYWRITE for COW so gdb can set breakpoints */
-	vdso_text_start = addr;
-	vma = _install_special_mapping(mm, addr, vdso_text_len,
+	vma = _install_special_mapping(mm, vdso_text_start, vdso_text_len,
 				       VM_READ|VM_EXEC|
 				       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
 				       &vdso_mapping);
-	rc = PTR_ERR(vma);
-	if (IS_ERR(vma))
-		goto out;
-	addr += vdso_text_len;
-	vma = _install_special_mapping(mm, addr, PAGE_SIZE,
-				       VM_READ|VM_MAYREAD|VM_PFNMAP,
-				       &vvar_mapping);
 	if (IS_ERR(vma)) {
-		do_munmap(mm, vdso_text_start, vdso_text_len, NULL);
+		do_munmap(mm, vvar_start, PAGE_SIZE, NULL);
 		rc = PTR_ERR(vma);
 	} else {
 		current->mm->context.vdso_base = vdso_text_start;

arch/s390/kernel/vdso64/vdso64.lds.S

@@ -13,6 +13,7 @@ ENTRY(_start)
 
 SECTIONS
 {
+	PROVIDE(_vdso_data = . - PAGE_SIZE);
 	. = VDSO64_LBASE + SIZEOF_HEADERS;
 
 	.hash		: { *(.hash) }			:text
@@ -94,9 +95,6 @@ SECTIONS
 	.debug_ranges	0 : { *(.debug_ranges) }
 	.gnu.attributes 0 : { KEEP (*(.gnu.attributes)) }
 
-	. = ALIGN(PAGE_SIZE);
-	PROVIDE(_vdso_data = .);
-
 	/DISCARD/	: {
 		*(.note.GNU-stack)
 		*(.branch_lt)