--- old/src/hotspot/share/runtime/os.hpp	2018-06-07 10:21:54.620707245 +0200
+++ new/src/hotspot/share/runtime/os.hpp	2018-06-07 10:21:54.468707518 +0200
@@ -302,6 +302,12 @@
     return _page_sizes[0];
   }
 
+  struct range_t { address addr; size_t size; };
+  // Given an address range, returns the largest inner range whose boundaries are page
+  //  aligned to os::vm_page_size().
+  // If the given range is too small to hold a full page, the resulting range.addr will be NULL.
+  static range_t inner_page_aligned_boundaries(address addr, size_t size);
+
   // Methods for tracing page sizes returned by the above method.
   // The region_{min,max}_size parameters should be the values
   // passed to page_size_for_region() and page_size should be the result of that