Memory Management: Fix coalesce to track holes in the page management

The heap memory coalesce algorithm previously did not account for the right page
start address and the hole carved out for the page table.  This change fixes
both issues

Change-Id: I730b546eb1966051c1d5dd8459d76a7943234bea
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/59813
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: Jenkins OP Build CI <op-jenkins+hostboot@us.ibm.com>
Tested-by: Jenkins OP HW <op-hw-jenkins+hostboot@us.ibm.com>
Reviewed-by: Nicholas E. Bofferding <bofferdn@us.ibm.com>

src/kernel/pagemgr.C

@@ -398,9 +398,24 @@ void PageManagerCore::coalesce( void )
         {
             // p needs to be the even buddy to prevent merging of wrong block.
             // To determine this, get the index of the block as if the whole
-            // page memory space were blocks of this size.
-            uint64_t p_idx = (reinterpret_cast<uint64_t>(p) - firstPageAddr())/
-                             ((1 << bucket)*PAGESIZE);
+            // page memory space were blocks of this size.  Note: have to
+            // take into account the page manager "hole" in the middle of the
+            // space
+            uint64_t p_idx = 0;
+            if(reinterpret_cast<uint64_t>(p) < VmmManager::pageTableOffset())
+            {
+                p_idx = (  reinterpret_cast<uint64_t>(p)
+                         - VmmManager::endPreservedOffset())/
+                            ((1 << bucket)*PAGESIZE);
+            }
+            else
+            {
+                p_idx = (  reinterpret_cast<uint64_t>(p)
+                         - (  VmmManager::pageTableOffset()
+                            + VmmManager::PTSIZE) )/
+                               ((1 << bucket)*PAGESIZE);
+            }
+
             if(0 != (p_idx % 2))  // odd index
             {
                 iv_heap[bucket].push(p);  // can't merge