1 /*
   2  * Copyright (c) 2012, 2016, 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 
  26 #include "precompiled.hpp"
  27 
  28 #include "memory/metaspace/constants.hpp"
  29 #include "memory/metaspace/commitMask.hpp"
  30 #include "memory/metaspace/metaspaceCommon.hpp"
  31 #include "runtime/stubRoutines.hpp"
  32 
  33 #include "utilities/align.hpp"
  34 #include "utilities/debug.hpp"
  35 
  36 namespace metaspace {
  37 
  38 #ifdef ASSERT
  39 
  40 volatile u1 x;
  41 
  42 void CommitMask::verify(bool slow) const {
  43 
  44   // Walk the whole commit mask.
  45   // For each 1 bit, check if the associated granule is accessible.
  46   // For each 0 bit, check if the associated granule is not accessible. Slow mode only.
  47 
  48   assert_is_aligned(_base, constants::commit_granule_bytes);
  49   assert_is_aligned(_word_size, constants::commit_granule_words);
  50 
  51   if (slow) {
  52     assert(CanUseSafeFetch32, "We need SafeFetch for this test.");
  53   }
  54 
  55   for (idx_t i = 0; i < size(); i ++) {
  56     const MetaWord* const p = _base + (i * constants::commit_granule_words);
  57     if (at(i)) {
  58       // Should be accessible. Just touch it.
  59       x ^= (u1*)p;
  60     } else {
  61       // Should not be accessible.
  62       if (slow) {
  63         // Note: results may differ between platforms. On Linux, this should be true since
  64         // we uncommit memory by setting protection to PROT_NONE. We may have to look if
  65         // this works as expected on other platforms.
  66         assert(os::is_readable_pointer(p) == false, "Should not be accessible.");
  67       }
  68     }
  69   }
  70 
  71 }
  72 
  73 #endif // ASSERT
  74 
  75 } // namespace metaspace
  76