1 /*
   2  * Copyright (c) 2018, 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 #include "precompiled.hpp"
  26 #include "asm/macroAssembler.inline.hpp"
  27 #include "gc/shared/barrierSet.hpp"
  28 #include "gc/shared/cardTable.hpp"
  29 #include "gc/shared/cardTableBarrierSet.hpp"
  30 #include "gc/shared/cardTableBarrierSetAssembler.hpp"
  31 
  32 #define __ masm->
  33 
  34 #ifdef PRODUCT
  35 #define BLOCK_COMMENT(str) /* nothing */
  36 #else
  37 #define BLOCK_COMMENT(str) __ block_comment(str)
  38 #endif
  39 
  40 #define BIND(label) bind(label); BLOCK_COMMENT(#label ":")
  41 
  42 #define TIMES_OOP (UseCompressedOops ? Address::times_4 : Address::times_8)
  43 
  44 void CardTableBarrierSetAssembler::gen_write_ref_array_post_barrier(MacroAssembler* masm, DecoratorSet decorators,
  45                                                                     Register addr, Register count, Register tmp) {
  46   BarrierSet *bs = BarrierSet::barrier_set();
  47   CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(bs);
  48   CardTable* ct = ctbs->card_table();
  49   intptr_t disp = (intptr_t) ct->byte_map_base();
  50 
  51   Label L_loop, L_done;
  52   const Register end = count;
  53   assert_different_registers(addr, end);
  54 
  55   __ testl(count, count);
  56   __ jcc(Assembler::zero, L_done); // zero count - nothing to do
  57 
  58 
  59 #ifdef _LP64
  60   __ leaq(end, Address(addr, count, TIMES_OOP, 0));  // end == addr+count*oop_size
  61   __ subptr(end, BytesPerHeapOop); // end - 1 to make inclusive
  62   __ shrptr(addr, CardTable::card_shift);
  63   __ shrptr(end, CardTable::card_shift);
  64   __ subptr(end, addr); // end --> cards count
  65 
  66   __ mov64(tmp, disp);
  67   __ addptr(addr, tmp);
  68 __ BIND(L_loop);
  69   __ movb(Address(addr, count, Address::times_1), 0);
  70   __ decrement(count);
  71   __ jcc(Assembler::greaterEqual, L_loop);
  72 #else
  73   __ lea(end,  Address(addr, count, Address::times_ptr, -wordSize));
  74   __ shrptr(addr, CardTable::card_shift);
  75   __ shrptr(end,   CardTable::card_shift);
  76   __ subptr(end, addr); // end --> count
  77 __ BIND(L_loop);
  78   Address cardtable(addr, count, Address::times_1, disp);
  79   __ movb(cardtable, 0);
  80   __ decrement(count);
  81   __ jcc(Assembler::greaterEqual, L_loop);
  82 #endif
  83 
  84 __ BIND(L_done);
  85 }
  86 
  87 void CardTableBarrierSetAssembler::store_check(MacroAssembler* masm, Register obj, Address dst) {
  88   // Does a store check for the oop in register obj. The content of
  89   // register obj is destroyed afterwards.
  90   BarrierSet* bs = BarrierSet::barrier_set();
  91 
  92   CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(bs);
  93   CardTable* ct = ctbs->card_table();
  94 
  95   __ shrptr(obj, CardTable::card_shift);
  96 
  97   Address card_addr;
  98 
  99   // The calculation for byte_map_base is as follows:
 100   // byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
 101   // So this essentially converts an address to a displacement and it will
 102   // never need to be relocated. On 64bit however the value may be too
 103   // large for a 32bit displacement.
 104   intptr_t byte_map_base = (intptr_t)ct->byte_map_base();
 105   if (__ is_simm32(byte_map_base)) {
 106     card_addr = Address(noreg, obj, Address::times_1, byte_map_base);
 107   } else {
 108     // By doing it as an ExternalAddress 'byte_map_base' could be converted to a rip-relative
 109     // displacement and done in a single instruction given favorable mapping and a
 110     // smarter version of as_Address. However, 'ExternalAddress' generates a relocation
 111     // entry and that entry is not properly handled by the relocation code.
 112     AddressLiteral cardtable((address)byte_map_base, relocInfo::none);
 113     Address index(noreg, obj, Address::times_1);
 114     card_addr = __ as_Address(ArrayAddress(cardtable, index));
 115   }
 116 
 117   int dirty = CardTable::dirty_card_val();
 118   if (UseCondCardMark) {
 119     Label L_already_dirty;
 120     if (ct->scanned_concurrently()) {
 121       __ membar(Assembler::StoreLoad);
 122     }
 123     __ cmpb(card_addr, dirty);
 124     __ jcc(Assembler::equal, L_already_dirty);
 125     __ movb(card_addr, dirty);
 126     __ bind(L_already_dirty);
 127   } else {
 128     __ movb(card_addr, dirty);
 129   }
 130 }
 131 
 132 void CardTableBarrierSetAssembler::oop_store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
 133                                                 Address dst, Register val, Register tmp1, Register tmp2) {
 134   bool in_heap = (decorators & IN_HEAP) != 0;
 135 
 136   bool is_array = (decorators & IS_ARRAY) != 0;
 137   bool on_anonymous = (decorators & ON_UNKNOWN_OOP_REF) != 0;
 138   bool precise = is_array || on_anonymous;
 139 
 140   bool needs_post_barrier = val != noreg && in_heap;
 141 
 142   BarrierSetAssembler::store_at(masm, decorators, type, dst, val, noreg, noreg);
 143   if (needs_post_barrier) {
 144     // flatten object address if needed
 145     if (!precise || (dst.index() == noreg && dst.disp() == 0)) {
 146       store_check(masm, dst.base(), dst);
 147     } else {
 148       __ lea(tmp1, dst);
 149       store_check(masm, tmp1, dst);
 150     }
 151   }
 152 }