rev 7618 : 8062063: Usage of UseHugeTLBFS, UseLargePagesInMetaspace and huge SurvivorAlignmentInBytes cause crashes in CMBitMapClosure::do_bit
Summary: Making sure committed memory is cleared when re-committed, even if using large pages.
Reviewed-by:
rev 7619 : [mq]: clear-in-listener
rev 7620 : [mq]: needs-zeroing-to-dirty

   1 /*
   2  * Copyright (c) 2014, 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 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "memory/memRegion.hpp"
  30 #include "runtime/virtualspace.hpp"
  31 #include "utilities/bitMap.hpp"
  32 
  33 // Virtual space management helper for a virtual space with an OS page allocation
  34 // granularity.
  35 // (De-)Allocation requests are always OS page aligned by passing a page index
  36 // and multiples of pages.
  37 // The implementation gives an error when trying to commit or uncommit pages that
  38 // have already been committed or uncommitted.
  39 class G1PageBasedVirtualSpace VALUE_OBJ_CLASS_SPEC {
  40   friend class VMStructs;
  41  private:
  42   // Reserved area addresses.
  43   char* _low_boundary;
  44   char* _high_boundary;
  45 
  46   // The commit/uncommit granularity in bytes.
  47   size_t _page_size;
  48 
  49   // Bitmap used for verification of commit/uncommit operations.
  50   BitMap _committed;
  51 
  52   // Bitmap used to keep track of which pages are dirty or not for _special
  53   // spaces. This is needed because for those spaces the underlying memory
  54   // will only be zero filled the first time it is committed. Calls to commit
  55   // will use this bitmap and return whether or not the memory is zero filled.
  56   BitMap _dirty;
  57 
  58   // Indicates that the entire space has been committed and pinned in memory,
  59   // os::commit_memory() or os::uncommit_memory() have no function.
  60   bool _special;
  61 
  62   // Indicates whether the committed space should be executable.
  63   bool _executable;
  64 
  65   // Returns the index of the page which contains the given address.
  66   uintptr_t  addr_to_page_index(char* addr) const;
  67   // Returns the address of the given page index.
  68   char*  page_start(uintptr_t index);
  69   // Returns the byte size of the given number of pages.
  70   size_t byte_size_for_pages(size_t num);
  71 
  72   // Returns true if the entire area is backed by committed memory.
  73   bool is_area_committed(uintptr_t start, size_t size_in_pages) const;
  74   // Returns true if the entire area is not backed by committed memory.
  75   bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const;
  76 
  77  public:
  78 
  79   // Commit the given area of pages starting at start being size_in_pages large.
  80   // Returns true if the given area is zero filled upon completion.
  81   bool commit(uintptr_t start, size_t size_in_pages);
  82 
  83   // Uncommit the given area of pages starting at start being size_in_pages large.
  84   void uncommit(uintptr_t start, size_t size_in_pages);
  85 
  86   // Initialization
  87   G1PageBasedVirtualSpace();
  88   bool initialize_with_granularity(ReservedSpace rs, size_t page_size);
  89 
  90   // Destruction
  91   ~G1PageBasedVirtualSpace();
  92 
  93   // Amount of reserved memory.
  94   size_t reserved_size() const;
  95   // Memory used in this virtual space.
  96   size_t committed_size() const;
  97   // Memory left to use/expand in this virtual space.
  98   size_t uncommitted_size() const;
  99 
 100   bool contains(const void* p) const;
 101 
 102   MemRegion reserved() {
 103     MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize);
 104     return x;
 105   }
 106 
 107   void release();
 108 
 109   void check_for_contiguity() PRODUCT_RETURN;
 110 
 111   // Debugging
 112   void print_on(outputStream* out) PRODUCT_RETURN;
 113   void print();
 114 };
 115 
 116 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
--- EOF ---