jdk8-mips64-public/hotspot: src/share/vm/memory/barrierSet.inline.hpp@2c022e432e10

8024974: Incorrect use of GC_locker::is_active()
Summary: SymbolTable and StringTable can make calls to GC_locker::is_active() outside a safepoint. This isn't safe because the GC_locker active state (lock count) is only updated at a safepoint and only remains valid as long as _needs_gc is true. However, outside a safepoint_needs_gc can change to false at any time, which makes it impossible to do a correct call to is_active() in that context. In this case these calls can just be removed since the input argument to basic_add() should never be on the heap and so there's no need to check the GC_locker state. This change also adjusts the assert() in is_active() to makes sure all calls to this function are always done under a safepoint.
Reviewed-by: brutisso, dcubed
Contributed-by: per.liden@oracle.com

     1 /*

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     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

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    23  */

    25 #ifndef SHARE_VM_MEMORY_BARRIERSET_INLINE_HPP

    26 #define SHARE_VM_MEMORY_BARRIERSET_INLINE_HPP

    28 #include "memory/barrierSet.hpp"

    29 #include "memory/cardTableModRefBS.hpp"

    31 // Inline functions of BarrierSet, which de-virtualize certain

    32 // performance-critical calls when the barrier is the most common

    33 // card-table kind.

    35 template <class T> void BarrierSet::write_ref_field_pre(T* field, oop new_val) {

    36   if (kind() == CardTableModRef) {

    37     ((CardTableModRefBS*)this)->inline_write_ref_field_pre(field, new_val);

    38   } else {

    39     write_ref_field_pre_work(field, new_val);

    40   }

    41 }

    43 void BarrierSet::write_ref_field(void* field, oop new_val) {

    44   if (kind() == CardTableModRef) {

    45     ((CardTableModRefBS*)this)->inline_write_ref_field(field, new_val);

    46   } else {

    47     write_ref_field_work(field, new_val);

    48   }

    49 }

    51 // count is number of array elements being written

    52 void BarrierSet::write_ref_array(HeapWord* start, size_t count) {

    53   assert(count <= (size_t)max_intx, "count too large");

    54   HeapWord* end = (HeapWord*)((char*)start + (count*heapOopSize));

    55   // In the case of compressed oops, start and end may potentially be misaligned;

    56   // so we need to conservatively align the first downward (this is not

    57   // strictly necessary for current uses, but a case of good hygiene and,

    58   // if you will, aesthetics) and the second upward (this is essential for

    59   // current uses) to a HeapWord boundary, so we mark all cards overlapping

    60   // this write. If this evolves in the future to calling a

    61   // logging barrier of narrow oop granularity, like the pre-barrier for G1

    62   // (mentioned here merely by way of example), we will need to change this

    63   // interface, so it is "exactly precise" (if i may be allowed the adverbial

    64   // redundancy for emphasis) and does not include narrow oop slots not

    65   // included in the original write interval.

    66   HeapWord* aligned_start = (HeapWord*)align_size_down((uintptr_t)start, HeapWordSize);

    67   HeapWord* aligned_end   = (HeapWord*)align_size_up  ((uintptr_t)end,   HeapWordSize);

    68   // If compressed oops were not being used, these should already be aligned

    69   assert(UseCompressedOops || (aligned_start == start && aligned_end == end),

    70          "Expected heap word alignment of start and end");

    71 #if 0

    72   warning("Post:\t" INTPTR_FORMAT "[" SIZE_FORMAT "] : [" INTPTR_FORMAT","INTPTR_FORMAT")\t",

    73                    start,            count,              aligned_start,   aligned_end);

    74 #endif

    75   write_ref_array_work(MemRegion(aligned_start, aligned_end));

    76 }

    79 void BarrierSet::write_region(MemRegion mr) {

    80   if (kind() == CardTableModRef) {

    81     ((CardTableModRefBS*)this)->inline_write_region(mr);

    82   } else {

    83     write_region_work(mr);

    84   }

    85 }

    87 #endif // SHARE_VM_MEMORY_BARRIERSET_INLINE_HPP

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

src/share/vm/memory/barrierSet.inline.hpp@2c022e432e10

src/share/vm/memory/barrierSet.inline.hpp