jdk8-mips64-public/hotspot: src/share/vm/oops/markOop.cpp@d8b3ef7ee3e5

6599425: 4/3 OopMapCache::lookup() can cause later crash or assert() failure
Summary: Add should_not_be_cached() to markOop and methodOop and query that status inOopMapCache::lookup()
Reviewed-by: coleenp, sspitsyn, jmasa

     1 /*

     2  * Copyright 1997-1999 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  */

    25 # include "incls/_precompiled.incl"

    26 # include "incls/_markOop.cpp.incl"

    29 void markOopDesc::print_on(outputStream* st) const {

    30   if (is_locked()) {

    31     st->print("locked(0x%lx)->", value());

    32     markOop(*(markOop*)value())->print_on(st);

    33   } else {

    34     assert(is_unlocked(), "just checking");

    35     st->print("mark(");

    36     st->print("hash %#lx,", hash());

    37     st->print("age %d)", age());

    38   }

    39 }

    42 // Give advice about whether the oop that contains this markOop

    43 // should be cached or not.

    44 bool markOopDesc::should_not_be_cached() const {

    45   // the cast is because decode_pointer() isn't marked const

    46   if (is_marked() && ((markOopDesc *)this)->decode_pointer() != NULL) {

    47     // If the oop containing this markOop is being forwarded, then

    48     // we are in the middle of GC and we do not want the containing

    49     // oop to be added to a cache. We have no way of knowing whether

    50     // the cache has already been visited by the current GC phase so

    51     // we don't know whether the forwarded oop will be properly

    52     // processed in this phase. If the forwarded oop is not properly

    53     // processed, then we'll see strange crashes or asserts during

    54     // the next GC run because the markOop will contain an unexpected

    55     // value.

    56     //

    57     // This situation has been seen when we are GC'ing a methodOop

    58     // because we use the methodOop while we're GC'ing it. Scary

    59     // stuff. Some of the uses the methodOop cause the methodOop to

    60     // be added to the OopMapCache in the instanceKlass as a side

    61     // effect. This check lets the cache maintainer know when a

    62     // cache addition would not be safe.

    63     return true;

    64   }

    66   // caching the containing oop should be just fine

    67   return false;

    68 }

Mercurial > jdk8-mips64-public > hotspot / file revision

src/share/vm/oops/markOop.cpp@d8b3ef7ee3e5

src/share/vm/oops/markOop.cpp