1 /*
   2  * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/cms/freeChunk.hpp"
  27 #include "utilities/copy.hpp"
  28 
  29 #ifndef PRODUCT
  30 
  31 #define baadbabeHeapWord badHeapWordVal
  32 #define deadbeefHeapWord 0xdeadbeef
  33 
  34 size_t const FreeChunk::header_size() {
  35   return sizeof(FreeChunk)/HeapWordSize;
  36 }
  37 
  38 void FreeChunk::mangleAllocated(size_t size) {
  39   // mangle all but the header of a just-allocated block
  40   // of storage
  41   assert(size >= MinChunkSize, "smallest size of object");
  42   // we can't assert that _size == size because this may be an
  43   // allocation out of a linear allocation block
  44   assert(sizeof(FreeChunk) % HeapWordSize == 0,
  45          "shouldn't write beyond chunk");
  46   HeapWord* addr = (HeapWord*)this;
  47   size_t hdr = header_size();
  48   Copy::fill_to_words(addr + hdr, size - hdr, baadbabeHeapWord);
  49 }
  50 
  51 void FreeChunk::mangleFreed(size_t sz) {
  52   assert(baadbabeHeapWord != deadbeefHeapWord, "Need distinct patterns");
  53   // mangle all but the header of a just-freed block of storage
  54   // just prior to passing it to the storage dictionary
  55   assert(sz >= MinChunkSize, "smallest size of object");
  56   assert(sz == size(), "just checking");
  57   HeapWord* addr = (HeapWord*)this;
  58   size_t hdr = header_size();
  59   Copy::fill_to_words(addr + hdr, sz - hdr, deadbeefHeapWord);
  60 }
  61 
  62 void FreeChunk::verifyList() const {
  63   FreeChunk* nextFC = next();
  64   if (nextFC != NULL) {
  65     assert(this == nextFC->prev(), "broken chain");
  66     assert(size() == nextFC->size(), "wrong size");
  67     nextFC->verifyList();
  68   }
  69 }
  70 #endif
  71 
  72 void FreeChunk::print_on(outputStream* st) {
  73   st->print_cr("Next: " PTR_FORMAT " Prev: " PTR_FORMAT " %s",
  74     p2i(next()), p2i(prev()), cantCoalesce() ? "[can't coalesce]" : "");
  75 }