#define __pa(x) (unsigned long)(x)
#define __va(x) (void *)(unsigned long)(x)
#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
+#define page_to_phys(page) (page_to_pfn(page) << PAGE_SHIFT)
#define pfn_valid(pfn) ((pfn) < max_mapnr)
#define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)