1 /*

     2  * Copyright 2005 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 #ifdef CHECK_UNHANDLED_OOPS

    25 

    26 // Detect unhanded oops in VM code

    27 

    28 // The design is that when an oop is declared on the stack as a local

    29 // variable, the oop is actually a C++ struct with constructor and

    30 // destructor.  The constructor adds the oop address on a list

    31 // off each thread and the destructor removes the oop.  At a potential

    32 // safepoint, the stack addresses of the local variable oops are trashed

    33 // with a recognizeable value.  If the local variable is used again, it

    34 // will segfault, indicating an unsafe use of that oop.

    35 // eg:

    36 //    oop o;    //register &o on list

    37 //    funct();  // if potential safepoint - causes clear_naked_oops()

    38 //              // which trashes o above.

    39 //    o->do_something();  // Crashes because o is unsafe.

    40 //

    41 // This code implements the details of the unhandled oop list on the thread.

    42 //

    43 

    44 class oop;

    45 class Thread;

    46 

    47 class UnhandledOopEntry {

    48  friend class UnhandledOops;

    49  private:

    50   oop* _oop_ptr;

    51   bool _ok_for_gc;

    52   address _pc;

    53  public:

    54   oop* oop_ptr() { return _oop_ptr; }

    55   UnhandledOopEntry() : _oop_ptr(NULL), _ok_for_gc(false), _pc(NULL) {}

    56   UnhandledOopEntry(oop* op, address pc) :

    57                         _oop_ptr(op),   _ok_for_gc(false), _pc(pc) {}

    58 };

    59 

    60 

    61 class UnhandledOops {

    62  friend class Thread;

    63  private:

    64   Thread* _thread;

    65   int _level;

    66   GrowableArray<UnhandledOopEntry> *_oop_list;

    67   void allow_unhandled_oop(oop* op);

    68   void clear_unhandled_oops();

    69   UnhandledOops(Thread* thread);

    70   ~UnhandledOops();

    71 

    72  public:

    73   static void dump_oops(UnhandledOops* list);

    74   void register_unhandled_oop(oop* op, address pc);

    75   void unregister_unhandled_oop(oop* op);

    76 };

    77 

    78 #ifdef _LP64

    79 const intptr_t BAD_OOP_ADDR =  0xfffffffffffffff1;

    80 #else

    81 const intptr_t BAD_OOP_ADDR =  0xfffffff1;

    82 #endif // _LP64

    83 #endif // CHECK_UNHANDLED_OOPS