1 /*

     2  * Copyright (c) 2019, 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_MEMORY_ARCHIVEUTILS_HPP

    26 #define SHARE_MEMORY_ARCHIVEUTILS_HPP

    27 

    28 #include "logging/log.hpp"

    29 #include "runtime/arguments.hpp"

    30 #include "utilities/bitMap.hpp"

    31 

    32 // ArchivePtrMarker is used to mark the location of pointers embedded in a CDS archive. E.g., when an

    33 // InstanceKlass k is dumped, we mark the location of the k->_name pointer by effectively calling

    34 // mark_pointer(/*ptr_loc=*/&k->_name). It's required that (_prt_base <= ptr_loc < _ptr_end). _ptr_base is

    35 // fixed, but _ptr_end can be expanded as more objects are dumped.

    36 class ArchivePtrMarker : AllStatic {

    37   static CHeapBitMap* _ptrmap;

    38   static address*     _ptr_base;

    39   static address*     _ptr_end;

    40 

    41   // Once _ptrmap is compacted, we don't allow bit marking anymore. This is to

    42   // avoid unintentional copy operations after the bitmap has been finalized and written.

    43   static bool         _compacted;

    44 public:

    45   static void initialize(CHeapBitMap* ptrmap, address* ptr_base, address* ptr_end);

    46   static void mark_pointer(address* ptr_loc);

    47   static void compact(address relocatable_base, address relocatable_end);

    48   static void compact(size_t max_non_null_offset);

    49 

    50   template <typename T>

    51   static void mark_pointer(T* ptr_loc) {

    52     mark_pointer((address*)ptr_loc);

    53   }

    54 

    55   static void expand_ptr_end(address *new_ptr_end) {

    56     assert(_ptr_end <= new_ptr_end, "must be");

    57     _ptr_end = new_ptr_end;

    58   }

    59 

    60   static CHeapBitMap* ptrmap() {

    61     return _ptrmap;

    62   }

    63 };

    64 

    65 // SharedDataRelocator is used to shift pointers in the CDS archive.

    66 //

    67 // The CDS archive is basically a contiguous block of memory (divided into several regions)

    68 // that contains multiple objects. The objects may contain direct pointers that point to other objects

    69 // within the archive (e.g., InstanceKlass::_name points to a Symbol in the archive). During dumping, we

    70 // built a bitmap that marks the locations of all these pointers (using ArchivePtrMarker, see comments above).

    71 //

    72 // The contents of the archive assumes that it’s mapped at the default SharedBaseAddress (e.g. 0x800000000).

    73 // If the archive ends up being mapped at a different address (e.g. 0x810000000), SharedDataRelocator

    74 // is used to shift each marked pointer by a delta (0x10000000 in this example), so that it points to

    75 // the actually mapped location of the target object.

    76 template <bool COMPACTING>

    77 class SharedDataRelocator: public BitMapClosure {

    78   // for all (address** p), where (is_marked(p) && _patch_base <= p && p < _patch_end) { *p += delta; }

    79 

    80   // Patch all pointers within this region that are marked.

    81   address* _patch_base;

    82   address* _patch_end;

    83 

    84   // Before patching, all pointers must point to this region.

    85   address _valid_old_base;

    86   address _valid_old_end;

    87 

    88   // After patching, all pointers must point to this region.

    89   address _valid_new_base;

    90   address _valid_new_end;

    91 

    92   // How much to relocate for each pointer.

    93   intx _delta;

    94 

    95   // The following fields are used only when COMPACTING == true;

    96   // The highest offset (inclusive) in the bitmap that contains a non-null pointer.

    97   // This is used at dump time to reduce the size of the bitmap (which may have been over-allocated).

    98   size_t _max_non_null_offset;

    99   CHeapBitMap* _ptrmap;

   100 

   101  public:

   102   SharedDataRelocator(address* patch_base, address* patch_end,

   103                       address valid_old_base, address valid_old_end,

   104                       address valid_new_base, address valid_new_end, intx delta,

   105                       CHeapBitMap* ptrmap = NULL) :

   106     _patch_base(patch_base), _patch_end(patch_end),

   107     _valid_old_base(valid_old_base), _valid_old_end(valid_old_end),

   108     _valid_new_base(valid_new_base), _valid_new_end(valid_new_end),

   109     _delta(delta) {

   110     log_debug(cds, reloc)("SharedDataRelocator::_patch_base     = " PTR_FORMAT, p2i(_patch_base));

   111     log_debug(cds, reloc)("SharedDataRelocator::_patch_end      = " PTR_FORMAT, p2i(_patch_end));

   112     log_debug(cds, reloc)("SharedDataRelocator::_valid_old_base = " PTR_FORMAT, p2i(_valid_old_base));

   113     log_debug(cds, reloc)("SharedDataRelocator::_valid_old_end  = " PTR_FORMAT, p2i(_valid_old_end));

   114     log_debug(cds, reloc)("SharedDataRelocator::_valid_new_base = " PTR_FORMAT, p2i(_valid_new_base));

   115     log_debug(cds, reloc)("SharedDataRelocator::_valid_new_end  = " PTR_FORMAT, p2i(_valid_new_end));

   116     if (COMPACTING) {

   117       assert(ptrmap != NULL, "must be");

   118       _max_non_null_offset = 0;

   119       _ptrmap = ptrmap;

   120     } else {

   121       // Don't touch the _max_non_null_offset and _ptrmap fields. Hopefully a good C++ compiler can

   122       // elide them.

   123       assert(ptrmap == NULL, "must be");

   124     }

   125   }

   126 

   127   size_t max_non_null_offset() {

   128     assert(COMPACTING, "must be");

   129     return _max_non_null_offset;

   130   }

   131 

   132   inline bool do_bit(size_t offset);

   133 };

   134 

   135 

   136 #endif // SHARE_MEMORY_ARCHIVEUTILS_HPP