card_table.cc revision f0605a0da70a495521e466c98255d469915a1f00
15d76c435082332ef79a22962386fa92a0870e378Ian Rogers/* 25d76c435082332ef79a22962386fa92a0870e378Ian Rogers * Copyright (C) 2010 The Android Open Source Project 35d76c435082332ef79a22962386fa92a0870e378Ian Rogers * 45d76c435082332ef79a22962386fa92a0870e378Ian Rogers * Licensed under the Apache License, Version 2.0 (the "License"); 55d76c435082332ef79a22962386fa92a0870e378Ian Rogers * you may not use this file except in compliance with the License. 65d76c435082332ef79a22962386fa92a0870e378Ian Rogers * You may obtain a copy of the License at 75d76c435082332ef79a22962386fa92a0870e378Ian Rogers * 85d76c435082332ef79a22962386fa92a0870e378Ian Rogers * http://www.apache.org/licenses/LICENSE-2.0 95d76c435082332ef79a22962386fa92a0870e378Ian Rogers * 105d76c435082332ef79a22962386fa92a0870e378Ian Rogers * Unless required by applicable law or agreed to in writing, software 115d76c435082332ef79a22962386fa92a0870e378Ian Rogers * distributed under the License is distributed on an "AS IS" BASIS, 125d76c435082332ef79a22962386fa92a0870e378Ian Rogers * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 135d76c435082332ef79a22962386fa92a0870e378Ian Rogers * See the License for the specific language governing permissions and 145d76c435082332ef79a22962386fa92a0870e378Ian Rogers * limitations under the License. 155d76c435082332ef79a22962386fa92a0870e378Ian Rogers */ 165d76c435082332ef79a22962386fa92a0870e378Ian Rogers 175d76c435082332ef79a22962386fa92a0870e378Ian Rogers#include "card_table.h" 185d76c435082332ef79a22962386fa92a0870e378Ian Rogers 195d76c435082332ef79a22962386fa92a0870e378Ian Rogers#include <sys/mman.h> /* for PROT_* */ 205d76c435082332ef79a22962386fa92a0870e378Ian Rogers 215d76c435082332ef79a22962386fa92a0870e378Ian Rogers#include "heap.h" 225d76c435082332ef79a22962386fa92a0870e378Ian Rogers#include "heap_bitmap.h" 235d76c435082332ef79a22962386fa92a0870e378Ian Rogers#include "logging.h" 24f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes#include "utils.h" 255d76c435082332ef79a22962386fa92a0870e378Ian Rogers 265d76c435082332ef79a22962386fa92a0870e378Ian Rogersnamespace art { 275d76c435082332ef79a22962386fa92a0870e378Ian Rogers/* 285d76c435082332ef79a22962386fa92a0870e378Ian Rogers * Maintain a card table from the write barrier. All writes of 295d76c435082332ef79a22962386fa92a0870e378Ian Rogers * non-NULL values to heap addresses should go through an entry in 305d76c435082332ef79a22962386fa92a0870e378Ian Rogers * WriteBarrier, and from there to here. 315d76c435082332ef79a22962386fa92a0870e378Ian Rogers * 325d76c435082332ef79a22962386fa92a0870e378Ian Rogers * The heap is divided into "cards" of GC_CARD_SIZE bytes, as 335d76c435082332ef79a22962386fa92a0870e378Ian Rogers * determined by GC_CARD_SHIFT. The card table contains one byte of 345d76c435082332ef79a22962386fa92a0870e378Ian Rogers * data per card, to be used by the GC. The value of the byte will be 355d76c435082332ef79a22962386fa92a0870e378Ian Rogers * one of GC_CARD_CLEAN or GC_CARD_DIRTY. 365d76c435082332ef79a22962386fa92a0870e378Ian Rogers * 375d76c435082332ef79a22962386fa92a0870e378Ian Rogers * After any store of a non-NULL object pointer into a heap object, 385d76c435082332ef79a22962386fa92a0870e378Ian Rogers * code is obliged to mark the card dirty. The setters in 395d76c435082332ef79a22962386fa92a0870e378Ian Rogers * object.h [such as SetFieldObject] do this for you. The 405d76c435082332ef79a22962386fa92a0870e378Ian Rogers * compiler also contains code to mark cards as dirty. 415d76c435082332ef79a22962386fa92a0870e378Ian Rogers * 425d76c435082332ef79a22962386fa92a0870e378Ian Rogers * The card table's base [the "biased card table"] gets set to a 435d76c435082332ef79a22962386fa92a0870e378Ian Rogers * rather strange value. In order to keep the JIT from having to 445d76c435082332ef79a22962386fa92a0870e378Ian Rogers * fabricate or load GC_DIRTY_CARD to store into the card table, 455d76c435082332ef79a22962386fa92a0870e378Ian Rogers * biased base is within the mmap allocation at a point where its low 465d76c435082332ef79a22962386fa92a0870e378Ian Rogers * byte is equal to GC_DIRTY_CARD. See CardTable::Init for details. 475d76c435082332ef79a22962386fa92a0870e378Ian Rogers */ 485d76c435082332ef79a22962386fa92a0870e378Ian Rogers 4939da035d99b6e81e8ca8d9b99da16984f2993dd6jeffhaoCardTable* CardTable::Create(const byte* heap_base, size_t heap_max_size, size_t growth_size) { 50f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes CardTable* bitmap = new CardTable; 51f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes bitmap->Init(heap_base, heap_max_size, growth_size); 52f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes return bitmap; 535d76c435082332ef79a22962386fa92a0870e378Ian Rogers} 545d76c435082332ef79a22962386fa92a0870e378Ian Rogers 555d76c435082332ef79a22962386fa92a0870e378Ian Rogers/* 565d76c435082332ef79a22962386fa92a0870e378Ian Rogers * Initializes the card table; must be called before any other 575d76c435082332ef79a22962386fa92a0870e378Ian Rogers * CardTable functions. 585d76c435082332ef79a22962386fa92a0870e378Ian Rogers */ 59f0605a0da70a495521e466c98255d469915a1f00Elliott Hughesvoid CardTable::Init(const byte* heap_base, size_t heap_max_size, size_t growth_size) { 605d76c435082332ef79a22962386fa92a0870e378Ian Rogers /* Set up the card table */ 615d76c435082332ef79a22962386fa92a0870e378Ian Rogers size_t length = heap_max_size / GC_CARD_SIZE; 625d76c435082332ef79a22962386fa92a0870e378Ian Rogers /* Allocate an extra 256 bytes to allow fixed low-byte of base */ 63f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes mem_map_.reset(MemMap::MapAnonymous("dalvik-card-table", NULL, length + 256, PROT_READ | PROT_WRITE)); 64f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes if (mem_map_.get() == NULL) { 65f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes std::string maps; 66f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes ReadFileToString("/proc/self/maps", &maps); 67f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes LOG(FATAL) << "couldn't allocate card table\n" << maps; 685d76c435082332ef79a22962386fa92a0870e378Ian Rogers } 69f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes byte* alloc_base = mem_map_->GetAddress(); 70f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes CHECK(alloc_base != NULL); 715d76c435082332ef79a22962386fa92a0870e378Ian Rogers base_ = alloc_base; 7239da035d99b6e81e8ca8d9b99da16984f2993dd6jeffhao length_ = growth_size / GC_CARD_SIZE; 7339da035d99b6e81e8ca8d9b99da16984f2993dd6jeffhao max_length_ = length; 745d76c435082332ef79a22962386fa92a0870e378Ian Rogers offset_ = 0; 755d76c435082332ef79a22962386fa92a0870e378Ian Rogers /* All zeros is the correct initial value; all clean. */ 765d76c435082332ef79a22962386fa92a0870e378Ian Rogers CHECK_EQ(GC_CARD_CLEAN, 0); 775d76c435082332ef79a22962386fa92a0870e378Ian Rogers biased_base_ = (byte *)((uintptr_t)alloc_base -((uintptr_t)heap_base >> GC_CARD_SHIFT)); 785d76c435082332ef79a22962386fa92a0870e378Ian Rogers if (((uintptr_t)biased_base_ & 0xff) != GC_CARD_DIRTY) { 795d76c435082332ef79a22962386fa92a0870e378Ian Rogers int offset = GC_CARD_DIRTY - (reinterpret_cast<int>(biased_base_) & 0xff); 805d76c435082332ef79a22962386fa92a0870e378Ian Rogers offset_ = offset + (offset < 0 ? 0x100 : 0); 815d76c435082332ef79a22962386fa92a0870e378Ian Rogers biased_base_ += offset_; 825d76c435082332ef79a22962386fa92a0870e378Ian Rogers } 835d76c435082332ef79a22962386fa92a0870e378Ian Rogers CHECK_EQ(reinterpret_cast<int>(biased_base_) & 0xff, GC_CARD_DIRTY); 845d76c435082332ef79a22962386fa92a0870e378Ian Rogers ClearCardTable(); 855d76c435082332ef79a22962386fa92a0870e378Ian Rogers} 865d76c435082332ef79a22962386fa92a0870e378Ian Rogers 875d76c435082332ef79a22962386fa92a0870e378Ian Rogersvoid CardTable::ClearCardTable() { 885d76c435082332ef79a22962386fa92a0870e378Ian Rogers CHECK(mem_map_->GetAddress() != NULL); 895d76c435082332ef79a22962386fa92a0870e378Ian Rogers memset(mem_map_->GetAddress(), GC_CARD_CLEAN, length_); 905d76c435082332ef79a22962386fa92a0870e378Ian Rogers} 915d76c435082332ef79a22962386fa92a0870e378Ian Rogers 925d76c435082332ef79a22962386fa92a0870e378Ian Rogers/* 935d76c435082332ef79a22962386fa92a0870e378Ian Rogers * Returns the first address in the heap which maps to this card. 945d76c435082332ef79a22962386fa92a0870e378Ian Rogers */ 955d76c435082332ef79a22962386fa92a0870e378Ian Rogersvoid* CardTable::AddrFromCard(const byte *cardAddr) const { 965d76c435082332ef79a22962386fa92a0870e378Ian Rogers CHECK(IsValidCard(cardAddr)); 975d76c435082332ef79a22962386fa92a0870e378Ian Rogers uintptr_t offset = cardAddr - biased_base_; 985d76c435082332ef79a22962386fa92a0870e378Ian Rogers return (void *)(offset << GC_CARD_SHIFT); 995d76c435082332ef79a22962386fa92a0870e378Ian Rogers} 1005d76c435082332ef79a22962386fa92a0870e378Ian Rogers 1015d76c435082332ef79a22962386fa92a0870e378Ian Rogersvoid CardTable::Scan(byte* base, byte* limit, Callback* visitor, void* arg) const { 1025d76c435082332ef79a22962386fa92a0870e378Ian Rogers byte* cur = CardFromAddr(base); 1035d76c435082332ef79a22962386fa92a0870e378Ian Rogers byte* end = CardFromAddr(limit); 1045d76c435082332ef79a22962386fa92a0870e378Ian Rogers while (cur < end) { 1055d76c435082332ef79a22962386fa92a0870e378Ian Rogers while (cur < end && *cur == GC_CARD_CLEAN) { 1065d76c435082332ef79a22962386fa92a0870e378Ian Rogers cur++; 1075d76c435082332ef79a22962386fa92a0870e378Ian Rogers } 1085d76c435082332ef79a22962386fa92a0870e378Ian Rogers byte* run_start = cur; 1095d76c435082332ef79a22962386fa92a0870e378Ian Rogers size_t run = 0; 1105d76c435082332ef79a22962386fa92a0870e378Ian Rogers while (cur < end && *cur == GC_CARD_DIRTY) { 1115d76c435082332ef79a22962386fa92a0870e378Ian Rogers run++; 1125d76c435082332ef79a22962386fa92a0870e378Ian Rogers cur++; 1135d76c435082332ef79a22962386fa92a0870e378Ian Rogers } 1145d76c435082332ef79a22962386fa92a0870e378Ian Rogers if (run > 0) { 1155d76c435082332ef79a22962386fa92a0870e378Ian Rogers byte* run_end = &cur[run]; 1165d76c435082332ef79a22962386fa92a0870e378Ian Rogers Heap::GetLiveBits()->VisitRange(reinterpret_cast<uintptr_t>(AddrFromCard(run_start)), 1175d76c435082332ef79a22962386fa92a0870e378Ian Rogers reinterpret_cast<uintptr_t>(AddrFromCard(run_end)), 1185d76c435082332ef79a22962386fa92a0870e378Ian Rogers visitor, arg); 1195d76c435082332ef79a22962386fa92a0870e378Ian Rogers } 1205d76c435082332ef79a22962386fa92a0870e378Ian Rogers } 1215d76c435082332ef79a22962386fa92a0870e378Ian Rogers} 1225d76c435082332ef79a22962386fa92a0870e378Ian Rogers 1235d76c435082332ef79a22962386fa92a0870e378Ian Rogers/* 1245d76c435082332ef79a22962386fa92a0870e378Ian Rogers * Verifies that gray objects are on a dirty card. 1255d76c435082332ef79a22962386fa92a0870e378Ian Rogers */ 1265d76c435082332ef79a22962386fa92a0870e378Ian Rogersvoid CardTable::VerifyCardTable() { 1275d76c435082332ef79a22962386fa92a0870e378Ian Rogers UNIMPLEMENTED(WARNING) << "Card table verification"; 1285d76c435082332ef79a22962386fa92a0870e378Ian Rogers} 1295d76c435082332ef79a22962386fa92a0870e378Ian Rogers 1305d76c435082332ef79a22962386fa92a0870e378Ian Rogers} // namespace art 131