1 /*
   2  * Copyright (c) 2003, 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_MEMORY_FILEMAP_HPP
  26 #define SHARE_VM_MEMORY_FILEMAP_HPP
  27 
  28 #include "memory/metaspaceShared.hpp"
  29 #include "memory/metaspace.hpp"
  30 
  31 // Layout of the file:
  32 //  header: dump of archive instance plus versioning info, datestamp, etc.
  33 //   [magic # = 0xF00BABA2]
  34 //  ... padding to align on page-boundary
  35 //  read-write space
  36 //  read-only space
  37 //  misc data (block offset table, string table, symbols, dictionary, etc.)
  38 //  tag(666)
  39 
  40 static const int JVM_SHARED_JARS_MAX = 128;
  41 static const int JVM_SPACENAME_MAX = 128;
  42 static const int JVM_IDENT_MAX = 256;
  43 static const int JVM_ARCH_MAX = 12;
  44 
  45 
  46 class Metaspace;
  47 
  48 class FileMapInfo : public CHeapObj<mtInternal> {
  49 private:
  50   enum {
  51     _invalid_version = -1,
  52     _current_version = 1
  53   };
  54 
  55   bool  _file_open;
  56   int   _fd;
  57   long  _file_offset;
  58 
  59   // FileMapHeader describes the shared space data in the file to be
  60   // mapped.  This structure gets written to a file.  It is not a class, so
  61   // that the compilers don't add any compiler-private data to it.
  62 
  63   struct FileMapHeader {
  64     int    _magic;                    // identify file type.
  65     int    _version;                  // (from enum, above.)
  66     size_t _alignment;                // how shared archive should be aligned
  67     int    _obj_alignment;            // value of ObjectAlignmentInBytes
  68 
  69     struct space_info {
  70       int    _file_offset;   // sizeof(this) rounded to vm page size
  71       char*  _base;          // copy-on-write base address
  72       size_t _capacity;      // for validity checking
  73       size_t _used;          // for setting space top on read
  74       bool   _read_only;     // read only space?
  75       bool   _allow_exec;    // executable code in space?
  76     } _space[MetaspaceShared::n_regions];
  77 
  78     // The following fields are all sanity checks for whether this archive
  79     // will function correctly with this JVM and the bootclasspath it's
  80     // invoked with.
  81     char  _arch[JVM_ARCH_MAX];            // architecture
  82     char  _jvm_ident[JVM_IDENT_MAX];      // identifier for jvm
  83     int   _num_jars;              // Number of jars in bootclasspath
  84 
  85     // Per jar file data:  timestamp, size.
  86 
  87     struct {
  88       time_t _timestamp;          // jar timestamp.
  89       long   _filesize;           // jar file size.
  90     } _jar[JVM_SHARED_JARS_MAX];
  91   } _header;
  92   const char* _full_path;
  93 
  94   static FileMapInfo* _current_info;
  95 
  96   bool  init_from_file(int fd);
  97   void  align_file_position();
  98 
  99 public:
 100   FileMapInfo() {
 101     _file_offset = 0;
 102     _file_open = false;
 103     _header._version = _invalid_version;
 104   }
 105 
 106   static int current_version()        { return _current_version; }
 107   void   populate_header(size_t alignment);
 108   bool   validate();
 109   void   invalidate();
 110   int    version()                    { return _header._version; }
 111   size_t alignment()                  { return _header._alignment; }
 112   size_t space_capacity(int i)        { return _header._space[i]._capacity; }
 113   char*  region_base(int i)           { return _header._space[i]._base; }
 114   struct FileMapHeader* header()      { return &_header; }
 115 
 116   static void set_current_info(FileMapInfo* info) {
 117     CDS_ONLY(_current_info = info;)
 118   }
 119 
 120   static FileMapInfo* current_info() {
 121     CDS_ONLY(return _current_info;)
 122     NOT_CDS(return NULL;)
 123   }
 124 
 125   static void assert_mark(bool check);
 126 
 127   // File manipulation.
 128   bool  initialize() NOT_CDS_RETURN_(false);
 129   bool  open_for_read();
 130   void  open_for_write();
 131   void  write_header();
 132   void  write_space(int i, Metaspace* space, bool read_only);
 133   void  write_region(int region, char* base, size_t size,
 134                      size_t capacity, bool read_only, bool allow_exec);
 135   void  write_bytes(const void* buffer, int count);
 136   void  write_bytes_aligned(const void* buffer, int count);
 137   char* map_region(int i);
 138   void  unmap_region(int i);
 139   void  close();
 140   bool  is_open() { return _file_open; }
 141   ReservedSpace reserve_shared_memory();
 142 
 143   // JVM/TI RedefineClasses() support:
 144   // Remap the shared readonly space to shared readwrite, private.
 145   bool  remap_shared_readonly_as_readwrite();
 146 
 147   // Errors.
 148   static void fail_stop(const char *msg, ...);
 149   void fail_continue(const char *msg, ...);
 150 
 151   // Return true if given address is in the mapped shared space.
 152   bool is_in_shared_space(const void* p) NOT_CDS_RETURN_(false);
 153   void print_shared_spaces() NOT_CDS_RETURN;
 154 
 155   static size_t shared_spaces_size() {
 156     return align_size_up(SharedReadOnlySize + SharedReadWriteSize +
 157                          SharedMiscDataSize + SharedMiscCodeSize,
 158                          os::vm_allocation_granularity());
 159   }
 160 
 161   // Stop CDS sharing and unmap CDS regions.
 162   static void stop_sharing_and_unmap(const char* msg);
 163 };
 164 
 165 #endif // SHARE_VM_MEMORY_FILEMAP_HPP