sandbox: vm: add page attribute getters

sandbox/vm/vm_page.c

@@ -77,6 +77,22 @@ vm_page_t *vm_page_get(phys_addr_t addr)
 	return pfn < page_array_count ? &page_array[pfn] : NULL;
 }
 
+phys_addr_t vm_page_get_paddr(vm_page_t *pg)
+{
+	return vm_page_get_pfn(pg) * VM_PAGE_SIZE;
+}
+
+void *vm_page_get_vaddr(vm_page_t *pg)
+{
+	/* TODO */
+	return NULL;
+}
+
+size_t vm_page_get_pfn(vm_page_t *pg)
+{
+	return ((uintptr_t)pg - (uintptr_t)page_array) / sizeof *pg;
+}
+
 size_t vm_page_order_to_bytes(vm_page_order_t order)
 {
 	if (order < 0 || order > VM_PAGE_MAX_ORDER) {