origin_page_for
origin = origin_page_for(page);
o_pages[i] = origin_page_for(pages[i]);
origin_page_for(page) = origin_p;
origin_page_for(&page[i]) = &origin[i];
return page_address(origin_page_for(page));
return shadow_page_for(page) && origin_page_for(page);
origin_page_for(page) = NULL;