kernel/arm: ensure page dir is correctly aligned

Page directory physical address must be aligned on 16K and
it must be mapped to a contiguous physical region.

Change-Id: I6723023c9deaa1c4a1081cf5a984a1766241a532
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5423
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: Adrien Destugues <[email protected]>

src/system/kernel/arch/arm/paging/32bit/ARMVMTranslationMap32Bit.cpp

@@ -100,10 +100,22 @@ ARMVMTranslationMap32Bit::Init(bool kernel)
 			return error;
 
 		// allocate the page directory
-		page_directory_entry* virtualPageDir = (page_directory_entry*)memalign(
-			PAGEDIR_ALIGN, PAGEDIR_SIZE);
-		if (virtualPageDir == NULL)
+		page_directory_entry *virtualPageDir = NULL;
+
+		virtual_address_restrictions virtualRestrictions = {};
+		virtualRestrictions.address_specification = B_ANY_KERNEL_ADDRESS;
+
+		physical_address_restrictions physicalRestrictions = {};
+		physicalRestrictions.alignment = PAGEDIR_ALIGN;
+
+		area_id pgdir_area = create_area_etc(B_SYSTEM_TEAM, "pgdir",
+			PAGEDIR_SIZE, B_CONTIGUOUS,
+			B_KERNEL_READ_AREA | B_KERNEL_WRITE_AREA, 0, 0,
+			&virtualRestrictions, &physicalRestrictions, (void **)&virtualPageDir);
+
+		if (pgdir_area < 0) {
 			return B_NO_MEMORY;
+		}
 
 		// look up the page directory's physical address
 		phys_addr_t physicalPageDir;