card_table.cc revision b3bd5f07884f5a1f2b84224363b1372d7c28d447
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" 24b3bd5f07884f5a1f2b84224363b1372d7c28d447Elliott Hughes#include "runtime.h" 25f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes#include "utils.h" 265d76c435082332ef79a22962386fa92a0870e378Ian Rogers 275d76c435082332ef79a22962386fa92a0870e378Ian Rogersnamespace art { 285d76c435082332ef79a22962386fa92a0870e378Ian Rogers/* 295d76c435082332ef79a22962386fa92a0870e378Ian Rogers * Maintain a card table from the write barrier. All writes of 305d76c435082332ef79a22962386fa92a0870e378Ian Rogers * non-NULL values to heap addresses should go through an entry in 315d76c435082332ef79a22962386fa92a0870e378Ian Rogers * WriteBarrier, and from there to here. 325d76c435082332ef79a22962386fa92a0870e378Ian Rogers * 335d76c435082332ef79a22962386fa92a0870e378Ian Rogers * The heap is divided into "cards" of GC_CARD_SIZE bytes, as 345d76c435082332ef79a22962386fa92a0870e378Ian Rogers * determined by GC_CARD_SHIFT. The card table contains one byte of 355d76c435082332ef79a22962386fa92a0870e378Ian Rogers * data per card, to be used by the GC. The value of the byte will be 365d76c435082332ef79a22962386fa92a0870e378Ian Rogers * one of GC_CARD_CLEAN or GC_CARD_DIRTY. 375d76c435082332ef79a22962386fa92a0870e378Ian Rogers * 385d76c435082332ef79a22962386fa92a0870e378Ian Rogers * After any store of a non-NULL object pointer into a heap object, 395d76c435082332ef79a22962386fa92a0870e378Ian Rogers * code is obliged to mark the card dirty. The setters in 405d76c435082332ef79a22962386fa92a0870e378Ian Rogers * object.h [such as SetFieldObject] do this for you. The 415d76c435082332ef79a22962386fa92a0870e378Ian Rogers * compiler also contains code to mark cards as dirty. 425d76c435082332ef79a22962386fa92a0870e378Ian Rogers * 435d76c435082332ef79a22962386fa92a0870e378Ian Rogers * The card table's base [the "biased card table"] gets set to a 445d76c435082332ef79a22962386fa92a0870e378Ian Rogers * rather strange value. In order to keep the JIT from having to 455d76c435082332ef79a22962386fa92a0870e378Ian Rogers * fabricate or load GC_DIRTY_CARD to store into the card table, 465d76c435082332ef79a22962386fa92a0870e378Ian Rogers * biased base is within the mmap allocation at a point where its low 4730fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers * byte is equal to GC_DIRTY_CARD. See CardTable::Create for details. 485d76c435082332ef79a22962386fa92a0870e378Ian Rogers */ 495d76c435082332ef79a22962386fa92a0870e378Ian Rogers 5030fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian RogersCardTable* CardTable::Create(const byte* heap_begin, size_t heap_capacity) { 515d76c435082332ef79a22962386fa92a0870e378Ian Rogers /* Set up the card table */ 5230fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers size_t capacity = heap_capacity / GC_CARD_SIZE; 535d76c435082332ef79a22962386fa92a0870e378Ian Rogers /* Allocate an extra 256 bytes to allow fixed low-byte of base */ 5430fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers UniquePtr<MemMap> mem_map(MemMap::MapAnonymous("dalvik-card-table", NULL, 5530fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers capacity + 256, PROT_READ | PROT_WRITE)); 5630fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers if (mem_map.get() == NULL) { 57f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes std::string maps; 58f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes ReadFileToString("/proc/self/maps", &maps); 59f0605a0da70a495521e466c98255d469915a1f00Elliott Hughes LOG(FATAL) << "couldn't allocate card table\n" << maps; 605d76c435082332ef79a22962386fa92a0870e378Ian Rogers } 6130fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers // All zeros is the correct initial value; all clean. Anonymous mmaps are initialized to zero, we 6230fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers // don't clear the card table to avoid unnecessary pages being allocated 635d76c435082332ef79a22962386fa92a0870e378Ian Rogers CHECK_EQ(GC_CARD_CLEAN, 0); 6430fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers 6530fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers byte* cardtable_begin = mem_map->Begin(); 6630fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers CHECK(cardtable_begin != NULL); 6730fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers 6830fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers // We allocated up to a bytes worth of extra space to allow biased_begin's byte value to equal 6930fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers // GC_CARD_DIRTY, compute a offset value to make this the case 7030fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers size_t offset = 0; 7130fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers byte* biased_begin = (byte *)((uintptr_t)cardtable_begin -((uintptr_t)heap_begin >> GC_CARD_SHIFT)); 7230fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers if (((uintptr_t)biased_begin & 0xff) != GC_CARD_DIRTY) { 7330fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers int delta = GC_CARD_DIRTY - (reinterpret_cast<int>(biased_begin) & 0xff); 7430fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers offset = delta + (delta < 0 ? 0x100 : 0); 7530fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers biased_begin += offset; 765d76c435082332ef79a22962386fa92a0870e378Ian Rogers } 7730fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers CHECK_EQ(reinterpret_cast<int>(biased_begin) & 0xff, GC_CARD_DIRTY); 7830fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers 7930fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers return new CardTable(mem_map.release(), biased_begin, offset); 805d76c435082332ef79a22962386fa92a0870e378Ian Rogers} 815d76c435082332ef79a22962386fa92a0870e378Ian Rogers 825d76c435082332ef79a22962386fa92a0870e378Ian Rogersvoid CardTable::ClearCardTable() { 8330fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers // TODO: clear just the range of the table that has been modified 8430fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers memset(mem_map_->Begin(), GC_CARD_CLEAN, mem_map_->Size()); 855d76c435082332ef79a22962386fa92a0870e378Ian Rogers} 865d76c435082332ef79a22962386fa92a0870e378Ian Rogers 8730fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogersvoid CardTable::CheckAddrIsInCardTable(const byte* addr) const { 8830fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers byte* cardAddr = biased_begin_ + ((uintptr_t)addr >> GC_CARD_SHIFT); 8930fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers if (!IsValidCard(cardAddr)) { 9030fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers byte* begin = mem_map_->Begin() + offset_; 9130fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers byte* end = mem_map_->End(); 9230fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers LOG(FATAL) << "Cardtable - begin: " << reinterpret_cast<void*>(begin) 9330fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers << " end: " << reinterpret_cast<void*>(end) 9430fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers << " addr: " << reinterpret_cast<const void*>(addr) 9530fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers << " cardAddr: " << reinterpret_cast<void*>(cardAddr); 9630fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers } 975d76c435082332ef79a22962386fa92a0870e378Ian Rogers} 985d76c435082332ef79a22962386fa92a0870e378Ian Rogers 9930fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogersvoid CardTable::Scan(byte* heap_begin, byte* heap_end, Callback* visitor, void* arg) const { 100b3bd5f07884f5a1f2b84224363b1372d7c28d447Elliott Hughes Heap* heap = Runtime::Current()->GetHeap(); 10130fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers byte* card_cur = CardFromAddr(heap_begin); 10230fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers byte* card_end = CardFromAddr(heap_end); 10330fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers while (card_cur < card_end) { 10430fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers while (card_cur < card_end && *card_cur == GC_CARD_CLEAN) { 10530fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers card_cur++; 1065d76c435082332ef79a22962386fa92a0870e378Ian Rogers } 10730fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers byte* run_start = card_cur; 1085d76c435082332ef79a22962386fa92a0870e378Ian Rogers size_t run = 0; 10930fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers while (card_cur < card_end && *card_cur == GC_CARD_DIRTY) { 1105d76c435082332ef79a22962386fa92a0870e378Ian Rogers run++; 11130fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers card_cur++; 1125d76c435082332ef79a22962386fa92a0870e378Ian Rogers } 1135d76c435082332ef79a22962386fa92a0870e378Ian Rogers if (run > 0) { 11430fab40ee5a07af6b8c3b6b0e9438071695a57f4Ian Rogers byte* run_end = &card_cur[run]; 115b3bd5f07884f5a1f2b84224363b1372d7c28d447Elliott Hughes heap->GetLiveBits()->VisitRange(reinterpret_cast<uintptr_t>(AddrFromCard(run_start)), 1165d76c435082332ef79a22962386fa92a0870e378Ian Rogers reinterpret_cast<uintptr_t>(AddrFromCard(run_end)), 1175d76c435082332ef79a22962386fa92a0870e378Ian Rogers visitor, arg); 1185d76c435082332ef79a22962386fa92a0870e378Ian Rogers } 1195d76c435082332ef79a22962386fa92a0870e378Ian Rogers } 1205d76c435082332ef79a22962386fa92a0870e378Ian Rogers} 1215d76c435082332ef79a22962386fa92a0870e378Ian Rogers 1225d76c435082332ef79a22962386fa92a0870e378Ian Rogersvoid CardTable::VerifyCardTable() { 1235d76c435082332ef79a22962386fa92a0870e378Ian Rogers UNIMPLEMENTED(WARNING) << "Card table verification"; 1245d76c435082332ef79a22962386fa92a0870e378Ian Rogers} 1255d76c435082332ef79a22962386fa92a0870e378Ian Rogers 1265d76c435082332ef79a22962386fa92a0870e378Ian Rogers} // namespace art 127