1 /*
   2  * Copyright (c) 1997, 2020, 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_UNIVERSE_HPP
  26 #define SHARE_MEMORY_UNIVERSE_HPP
  27 
  28 #include "gc/shared/verifyOption.hpp"
  29 #include "oops/array.hpp"
  30 #include "oops/oopHandle.hpp"
  31 #include "runtime/handles.hpp"
  32 #include "utilities/growableArray.hpp"
  33 
  34 // Universe is a name space holding known system classes and objects in the VM.
  35 //
  36 // Loaded classes are accessible through the SystemDictionary.
  37 //
  38 // The object heap is allocated and accessed through Universe, and various allocation
  39 // support is provided. Allocation by the interpreter and compiled code is done inline
  40 // and bails out to Scavenge::invoke_and_allocate.
  41 
  42 class CollectedHeap;
  43 class DeferredObjAllocEvent;
  44 class OopStorage;
  45 
  46 // A helper class for caching a Method* when the user of the cache
  47 // only cares about the latest version of the Method*.  This cache safely
  48 // interacts with the RedefineClasses API.
  49 
  50 class LatestMethodCache : public CHeapObj<mtClass> {
  51   // We save the Klass* and the idnum of Method* in order to get
  52   // the current cached Method*.
  53  private:
  54   Klass*                _klass;
  55   int                   _method_idnum;
  56 
  57  public:
  58   LatestMethodCache()   { _klass = NULL; _method_idnum = -1; }
  59   ~LatestMethodCache()  { _klass = NULL; _method_idnum = -1; }
  60 
  61   void   init(Klass* k, Method* m);
  62   Klass* klass() const           { return _klass; }
  63   int    method_idnum() const    { return _method_idnum; }
  64 
  65   Method* get_method();
  66 
  67   // CDS support.  Replace the klass in this with the archive version
  68   // could use this for Enhanced Class Redefinition also.
  69   void serialize(SerializeClosure* f) {
  70     f->do_ptr((void**)&_klass);
  71   }
  72   void metaspace_pointers_do(MetaspaceClosure* it);
  73 };
  74 
  75 class Universe: AllStatic {
  76   // Ugh.  Universe is much too friendly.
  77   friend class MarkSweep;
  78   friend class oopDesc;
  79   friend class ClassLoader;
  80   friend class SystemDictionary;
  81   friend class ReservedHeapSpace;
  82   friend class VMStructs;
  83   friend class VM_PopulateDumpSharedSpace;
  84   friend class Metaspace;
  85   friend class MetaspaceShared;
  86 
  87   friend jint  universe_init();
  88   friend void  universe2_init();
  89   friend bool  universe_post_init();
  90   friend void  universe_post_module_init();
  91 
  92  private:
  93   // Known classes in the VM
  94   static Klass* _typeArrayKlassObjs[T_LONG+1];
  95   static Klass* _objectArrayKlassObj;
  96 
  97   // Known objects in the VM
  98   static OopHandle    _main_thread_group;             // Reference to the main thread group object
  99   static OopHandle    _system_thread_group;           // Reference to the system thread group object
 100 
 101   static OopHandle    _the_empty_class_array;         // Canonicalized obj array of type java.lang.Class
 102   static OopHandle    _the_null_string;               // A cache of "null" as a Java string
 103   static OopHandle    _the_min_jint_string;           // A cache of "-2147483648" as a Java string
 104 
 105   static OopHandle    _the_null_sentinel;             // A unique object pointer unused except as a sentinel for null.
 106 
 107   // preallocated error objects (no backtrace)
 108   static OopHandle    _out_of_memory_errors;
 109 
 110   // preallocated cause message for delayed StackOverflowError
 111   static OopHandle    _delayed_stack_overflow_error_message;
 112 
 113   static LatestMethodCache* _finalizer_register_cache; // static method for registering finalizable objects
 114   static LatestMethodCache* _loader_addClass_cache;    // method for registering loaded classes in class loader vector
 115   static LatestMethodCache* _throw_illegal_access_error_cache; // Unsafe.throwIllegalAccessError() method
 116   static LatestMethodCache* _throw_no_such_method_error_cache; // Unsafe.throwNoSuchMethodError() method
 117   static LatestMethodCache* _do_stack_walk_cache;      // method for stack walker callback
 118 
 119   static Array<int>*            _the_empty_int_array;            // Canonicalized int array
 120   static Array<u2>*             _the_empty_short_array;          // Canonicalized short array
 121   static Array<Klass*>*         _the_empty_klass_array;          // Canonicalized klass array
 122   static Array<InstanceKlass*>* _the_empty_instance_klass_array; // Canonicalized instance klass array
 123   static Array<Method*>*        _the_empty_method_array;         // Canonicalized method array
 124 
 125   static Array<Klass*>*  _the_array_interfaces_array;
 126 
 127   // array of preallocated error objects with backtrace
 128   static OopHandle     _preallocated_out_of_memory_error_array;
 129 
 130   // number of preallocated error objects available for use
 131   static volatile jint _preallocated_out_of_memory_error_avail_count;
 132 
 133   static OopHandle    _null_ptr_exception_instance;   // preallocated exception object
 134   static OopHandle    _arithmetic_exception_instance; // preallocated exception object
 135   static OopHandle    _virtual_machine_error_instance; // preallocated exception object
 136 
 137   // References waiting to be transferred to the ReferenceHandler
 138   static OopHandle    _reference_pending_list;
 139 
 140   // The particular choice of collected heap.
 141   static CollectedHeap* _collectedHeap;
 142 
 143   static intptr_t _non_oop_bits;
 144   static intptr_t _non_heap_offset;
 145 
 146   // array of dummy objects used with +FullGCAlot
 147   debug_only(static OopHandle   _fullgc_alot_dummy_array;)
 148   debug_only(static int         _fullgc_alot_dummy_next;)
 149 
 150   // Compiler/dispatch support
 151   static int  _base_vtable_size;                      // Java vtbl size of klass Object (in words)
 152 
 153   // Initialization
 154   static bool _bootstrapping;                         // true during genesis
 155   static bool _module_initialized;                    // true after call_initPhase2 called
 156   static bool _fully_initialized;                     // true after universe_init and initialize_vtables called
 157 
 158   // the array of preallocated errors with backtraces
 159   static objArrayOop  preallocated_out_of_memory_errors();
 160 
 161   static objArrayOop out_of_memory_errors();
 162   // generate an out of memory error; if possible using an error with preallocated backtrace;
 163   // otherwise return the given default error.
 164   static oop        gen_out_of_memory_error(oop default_err);
 165 
 166   // Historic gc information
 167   static size_t _heap_capacity_at_last_gc;
 168   static size_t _heap_used_at_last_gc;
 169 
 170   static OopStorage* _vm_weak;
 171   static OopStorage* _vm_global;
 172 
 173   static jint initialize_heap();
 174   static void initialize_tlab();
 175   static void initialize_basic_type_mirrors(TRAPS);
 176   static void fixup_mirrors(TRAPS);
 177 
 178   static void reinitialize_vtable_of(Klass* k, TRAPS);
 179   static void reinitialize_vtables(TRAPS);
 180   static void reinitialize_itables(TRAPS);
 181   static void compute_base_vtable_size();             // compute vtable size of class Object
 182 
 183   static void genesis(TRAPS);                         // Create the initial world
 184 
 185   // Mirrors for primitive classes (created eagerly)
 186   static oop check_mirror(oop m) {
 187     assert(m != NULL, "mirror not initialized");
 188     return m;
 189   }
 190 
 191   // Debugging
 192   static int _verify_count;                           // number of verifies done
 193 
 194   // True during call to verify().  Should only be set/cleared in verify().
 195   static bool _verify_in_progress;
 196   static long verify_flags;
 197 
 198   static uintptr_t _verify_oop_mask;
 199   static uintptr_t _verify_oop_bits;
 200 
 201  public:
 202   static void calculate_verify_data(HeapWord* low_boundary, HeapWord* high_boundary) PRODUCT_RETURN;
 203 
 204   // Known classes in the VM
 205   static Klass* boolArrayKlassObj()                 { return typeArrayKlassObj(T_BOOLEAN); }
 206   static Klass* byteArrayKlassObj()                 { return typeArrayKlassObj(T_BYTE); }
 207   static Klass* charArrayKlassObj()                 { return typeArrayKlassObj(T_CHAR); }
 208   static Klass* intArrayKlassObj()                  { return typeArrayKlassObj(T_INT); }
 209   static Klass* shortArrayKlassObj()                { return typeArrayKlassObj(T_SHORT); }
 210   static Klass* longArrayKlassObj()                 { return typeArrayKlassObj(T_LONG); }
 211   static Klass* floatArrayKlassObj()                { return typeArrayKlassObj(T_FLOAT); }
 212   static Klass* doubleArrayKlassObj()               { return typeArrayKlassObj(T_DOUBLE); }
 213 
 214   static Klass* objectArrayKlassObj()               { return _objectArrayKlassObj; }
 215 
 216   static Klass* typeArrayKlassObj(BasicType t) {
 217     assert((uint)t >= T_BOOLEAN, "range check for type: %s", type2name(t));
 218     assert((uint)t < T_LONG+1,   "range check for type: %s", type2name(t));
 219     assert(_typeArrayKlassObjs[t] != NULL, "domain check");
 220     return _typeArrayKlassObjs[t];
 221   }
 222 
 223   // Known objects in the VM
 224   static oop int_mirror();
 225   static oop float_mirror();
 226   static oop double_mirror();
 227   static oop byte_mirror();
 228   static oop bool_mirror();
 229   static oop char_mirror();
 230   static oop long_mirror();
 231   static oop short_mirror();
 232   static oop void_mirror();
 233 
 234   // Table of primitive type mirrors, excluding T_OBJECT and T_ARRAY
 235   // but including T_VOID, hence the index including T_VOID
 236   static OopHandle _mirrors[T_VOID+1];
 237 
 238   static oop java_mirror(BasicType t);
 239   static void replace_mirror(BasicType t, oop obj);
 240   static void clear_basic_type_mirrors();
 241 
 242   static oop      main_thread_group();
 243   static void set_main_thread_group(oop group);
 244 
 245   static oop      system_thread_group();
 246   static void set_system_thread_group(oop group);
 247 
 248   static objArrayOop  the_empty_class_array ();
 249 
 250   static oop          the_null_string();
 251   static oop          the_min_jint_string();
 252 
 253   static oop          null_ptr_exception_instance();
 254   static oop          arithmetic_exception_instance();
 255   static oop          virtual_machine_error_instance();
 256   static oop          vm_exception()                  { return virtual_machine_error_instance(); }
 257 
 258   static Array<Klass*>* the_array_interfaces_array()  { return _the_array_interfaces_array;   }
 259   static Method*      finalizer_register_method()     { return _finalizer_register_cache->get_method(); }
 260   static Method*      loader_addClass_method()        { return _loader_addClass_cache->get_method(); }
 261 
 262   static Method*      throw_illegal_access_error()    { return _throw_illegal_access_error_cache->get_method(); }
 263   static Method*      throw_no_such_method_error()    { return _throw_no_such_method_error_cache->get_method(); }
 264 
 265   static Method*      do_stack_walk_method()          { return _do_stack_walk_cache->get_method(); }
 266 
 267   static oop          the_null_sentinel();
 268   static address      the_null_sentinel_addr()        { return (address) &_the_null_sentinel;  }
 269 
 270   // Function to initialize these
 271   static void initialize_known_methods(TRAPS);
 272 
 273   static void create_preallocated_out_of_memory_errors(TRAPS);
 274 
 275   // Reference pending list manipulation.  Access is protected by
 276   // Heap_lock.  The getter, setter and predicate require the caller
 277   // owns the lock.  Swap is used by parallel non-concurrent reference
 278   // processing threads, where some higher level controller owns
 279   // Heap_lock, so requires the lock is locked, but not necessarily by
 280   // the current thread.
 281   static oop          reference_pending_list();
 282   static void         clear_reference_pending_list();
 283   static bool         has_reference_pending_list();
 284   static oop          swap_reference_pending_list(oop list);
 285 
 286   static Array<int>*             the_empty_int_array()    { return _the_empty_int_array; }
 287   static Array<u2>*              the_empty_short_array()  { return _the_empty_short_array; }
 288   static Array<Method*>*         the_empty_method_array() { return _the_empty_method_array; }
 289   static Array<Klass*>*          the_empty_klass_array()  { return _the_empty_klass_array; }
 290   static Array<InstanceKlass*>*  the_empty_instance_klass_array() { return _the_empty_instance_klass_array; }
 291 
 292   // OutOfMemoryError support. Returns an error with the required message. The returned error
 293   // may or may not have a backtrace. If error has a backtrace then the stack trace is already
 294   // filled in.
 295   static oop out_of_memory_error_java_heap();
 296   static oop out_of_memory_error_c_heap();
 297   static oop out_of_memory_error_metaspace();
 298   static oop out_of_memory_error_class_metaspace();
 299   static oop out_of_memory_error_array_size();
 300   static oop out_of_memory_error_gc_overhead_limit();
 301   static oop out_of_memory_error_realloc_objects();
 302 
 303   // Throw default _out_of_memory_error_retry object as it will never propagate out of the VM
 304   static oop out_of_memory_error_retry();
 305   static oop delayed_stack_overflow_error_message();
 306 
 307   // The particular choice of collected heap.
 308   static CollectedHeap* heap() { return _collectedHeap; }
 309 
 310   // Reserve Java heap and determine CompressedOops mode
 311   static ReservedHeapSpace reserve_heap(size_t heap_size, size_t alignment);
 312 
 313   // Historic gc information
 314   static size_t get_heap_free_at_last_gc()             { return _heap_capacity_at_last_gc - _heap_used_at_last_gc; }
 315   static size_t get_heap_used_at_last_gc()             { return _heap_used_at_last_gc; }
 316   static void update_heap_info_at_gc();
 317 
 318   // Global OopStorages
 319   static OopStorage* vm_weak();
 320   static OopStorage* vm_global();
 321   static void oopstorage_init();
 322 
 323   // Testers
 324   static bool is_bootstrapping()                      { return _bootstrapping; }
 325   static bool is_module_initialized()                 { return _module_initialized; }
 326   static bool is_fully_initialized()                  { return _fully_initialized; }
 327 
 328   static bool        on_page_boundary(void* addr);
 329   static bool        should_fill_in_stack_trace(Handle throwable);
 330   static void check_alignment(uintx size, uintx alignment, const char* name);
 331 
 332   // CDS support
 333   static void serialize(SerializeClosure* f);
 334 
 335   // Apply "f" to all klasses for basic types (classes not present in
 336   // SystemDictionary).
 337   static void basic_type_classes_do(void f(Klass*));
 338   static void basic_type_classes_do(KlassClosure* closure);
 339   static void metaspace_pointers_do(MetaspaceClosure* it);
 340 
 341   // Debugging
 342   enum VERIFY_FLAGS {
 343     Verify_Threads = 1,
 344     Verify_Heap = 2,
 345     Verify_SymbolTable = 4,
 346     Verify_StringTable = 8,
 347     Verify_CodeCache = 16,
 348     Verify_SystemDictionary = 32,
 349     Verify_ClassLoaderDataGraph = 64,
 350     Verify_MetaspaceUtils = 128,
 351     Verify_JNIHandles = 256,
 352     Verify_CodeCacheOops = 512,
 353     Verify_ResolvedMethodTable = 1024,
 354     Verify_All = -1
 355   };
 356   static void initialize_verify_flags();
 357   static bool should_verify_subset(uint subset);
 358   static bool verify_in_progress() { return _verify_in_progress; }
 359   static void verify(VerifyOption option, const char* prefix);
 360   static void verify(const char* prefix) {
 361     verify(VerifyOption_Default, prefix);
 362   }
 363   static void verify() {
 364     verify("");
 365   }
 366 
 367   static int  verify_count()       { return _verify_count; }
 368   static void print_on(outputStream* st);
 369   static void print_heap_at_SIGBREAK();
 370   static void print_heap_before_gc();
 371   static void print_heap_after_gc();
 372 
 373   // Change the number of dummy objects kept reachable by the full gc dummy
 374   // array; this should trigger relocation in a sliding compaction collector.
 375   debug_only(static bool release_fullgc_alot_dummy();)
 376   // The non-oop pattern (see compiledIC.hpp, etc)
 377   static void*   non_oop_word();
 378 
 379   // Oop verification (see MacroAssembler::verify_oop)
 380   static uintptr_t verify_oop_mask()          PRODUCT_RETURN0;
 381   static uintptr_t verify_oop_bits()          PRODUCT_RETURN0;
 382   static uintptr_t verify_mark_bits()         PRODUCT_RETURN0;
 383   static uintptr_t verify_mark_mask()         PRODUCT_RETURN0;
 384 
 385   // Compiler support
 386   static int base_vtable_size()               { return _base_vtable_size; }
 387 
 388   static intptr_t non_heap_offset() {
 389     assert(_non_heap_offset != 0, "Should be initialized.");
 390     return _non_heap_offset;
 391   }
 392 };
 393 
 394 #endif // SHARE_MEMORY_UNIVERSE_HPP