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src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.hpp

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rev 6992 : 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: kbarrett, tschatzl


  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   // Indicates that the entire space has been committed and pinned in memory,
  53   // os::commit_memory() or os::uncommit_memory() have no function.
  54   bool _special;
  55 
  56   // Indicates whether the committed space should be executable.
  57   bool _executable;
  58 
  59   // Returns the index of the page which contains the given address.
  60   uintptr_t  addr_to_page_index(char* addr) const;
  61   // Returns the address of the given page index.
  62   char*  page_start(uintptr_t index);
  63   // Returns the byte size of the given number of pages.
  64   size_t byte_size_for_pages(size_t num);
  65 
  66   // Returns true if the entire area is backed by committed memory.
  67   bool is_area_committed(uintptr_t start, size_t size_in_pages) const;
  68   // Returns true if the entire area is not backed by committed memory.
  69   bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const;
  70 
  71  public:
  72 
  73   // Commit the given area of pages starting at start being size_in_pages large.
  74   MemRegion commit(uintptr_t start, size_t size_in_pages);

  75 
  76   // Uncommit the given area of pages starting at start being size_in_pages large.
  77   MemRegion uncommit(uintptr_t start, size_t size_in_pages);
  78 
  79   bool special() const { return _special; }
  80 
  81   // Initialization
  82   G1PageBasedVirtualSpace();
  83   bool initialize_with_granularity(ReservedSpace rs, size_t page_size);
  84 
  85   // Destruction
  86   ~G1PageBasedVirtualSpace();
  87 
  88   // Amount of reserved memory.
  89   size_t reserved_size() const;
  90   // Memory used in this virtual space.
  91   size_t committed_size() const;
  92   // Memory left to use/expand in this virtual space.
  93   size_t uncommitted_size() const;
  94 
  95   bool contains(const void* p) const;
  96 
  97   MemRegion reserved() {
  98     MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize);
  99     return x;


  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;
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