124 lines
4.3 KiB
C++
124 lines
4.3 KiB
C++
/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_RUNTIME_GC_ACCOUNTING_READ_BARRIER_TABLE_H_
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#define ART_RUNTIME_GC_ACCOUNTING_READ_BARRIER_TABLE_H_
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#include <sys/mman.h> // For the PROT_* and MAP_* constants.
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#include "base/bit_utils.h"
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#include "base/locks.h"
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#include "base/mem_map.h"
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#include "gc/space/space.h"
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#include "runtime_globals.h"
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namespace art {
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namespace gc {
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namespace accounting {
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// Used to decide whether to take the read barrier fast/slow paths for
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// kUseTableLookupReadBarrier. If an entry is set, take the read
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// barrier slow path. There's an entry per region.
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class ReadBarrierTable {
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public:
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ReadBarrierTable() {
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size_t capacity = static_cast<size_t>(kHeapCapacity / kRegionSize);
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DCHECK_EQ(kHeapCapacity / kRegionSize,
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static_cast<uint64_t>(static_cast<size_t>(kHeapCapacity / kRegionSize)));
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std::string error_msg;
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mem_map_ = MemMap::MapAnonymous("read barrier table",
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capacity,
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PROT_READ | PROT_WRITE,
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/*low_4gb=*/ false,
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&error_msg);
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CHECK(mem_map_.IsValid() && mem_map_.Begin() != nullptr)
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<< "couldn't allocate read barrier table: " << error_msg;
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}
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void ClearForSpace(space::ContinuousSpace* space) {
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uint8_t* entry_start = EntryFromAddr(space->Begin());
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uint8_t* entry_end = EntryFromAddr(space->Limit());
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memset(reinterpret_cast<void*>(entry_start), 0, entry_end - entry_start);
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}
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void Clear(uint8_t* start_addr, uint8_t* end_addr) {
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DCHECK(IsValidHeapAddr(start_addr)) << start_addr;
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DCHECK(IsValidHeapAddr(end_addr)) << end_addr;
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DCHECK_ALIGNED(start_addr, kRegionSize);
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DCHECK_ALIGNED(end_addr, kRegionSize);
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uint8_t* entry_start = EntryFromAddr(start_addr);
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uint8_t* entry_end = EntryFromAddr(end_addr);
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memset(reinterpret_cast<void*>(entry_start), 0, entry_end - entry_start);
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}
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bool IsSet(const void* heap_addr) const {
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DCHECK(IsValidHeapAddr(heap_addr)) << heap_addr;
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uint8_t entry_value = *EntryFromAddr(heap_addr);
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DCHECK(entry_value == 0 || entry_value == kSetEntryValue);
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return entry_value == kSetEntryValue;
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}
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void ClearAll() {
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mem_map_.MadviseDontNeedAndZero();
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}
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void SetAll() {
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memset(mem_map_.Begin(), kSetEntryValue, mem_map_.Size());
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}
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bool IsAllCleared() const {
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for (uint32_t* p = reinterpret_cast<uint32_t*>(mem_map_.Begin());
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p < reinterpret_cast<uint32_t*>(mem_map_.End()); ++p) {
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if (*p != 0) {
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return false;
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}
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}
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return true;
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}
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// This should match RegionSpace::kRegionSize. static_assert'ed in concurrent_copying.h.
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static constexpr size_t kRegionSize = 256 * KB;
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private:
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static constexpr uint64_t kHeapCapacity = 4ULL * GB; // low 4gb.
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static constexpr uint8_t kSetEntryValue = 0x01;
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uint8_t* EntryFromAddr(const void* heap_addr) const {
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DCHECK(IsValidHeapAddr(heap_addr)) << heap_addr;
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uint8_t* entry_addr = mem_map_.Begin() + reinterpret_cast<uintptr_t>(heap_addr) / kRegionSize;
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DCHECK(IsValidEntry(entry_addr)) << "heap_addr: " << heap_addr
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<< " entry_addr: " << reinterpret_cast<void*>(entry_addr);
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return entry_addr;
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}
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bool IsValidHeapAddr(const void* heap_addr) const {
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#ifdef __LP64__
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return reinterpret_cast<uint64_t>(heap_addr) < kHeapCapacity;
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#else
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UNUSED(heap_addr);
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return true;
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#endif
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}
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bool IsValidEntry(const uint8_t* entry_addr) const {
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uint8_t* begin = mem_map_.Begin();
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uint8_t* end = mem_map_.End();
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return entry_addr >= begin && entry_addr < end;
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}
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MemMap mem_map_;
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};
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} // namespace accounting
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} // namespace gc
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} // namespace art
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#endif // ART_RUNTIME_GC_ACCOUNTING_READ_BARRIER_TABLE_H_
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