1 files changed, 124 insertions, 0 deletions
diff --git a/runtime/gc/accounting/card_table.cc b/runtime/gc/accounting/card_table.cc
new file mode 100644
index 0000000000..4f2ae26c37
--- /dev/null
+++ b/runtime/gc/accounting/card_table.cc
@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "card_table.h"
+
+#include "base/logging.h"
+#include "card_table-inl.h"
+#include "gc/heap.h"
+#include "gc/space/space.h"
+#include "heap_bitmap.h"
+#include "runtime.h"
+#include "utils.h"
+
+namespace art {
+namespace gc {
+namespace accounting {
+
+/*
+ * Maintain a card table from the write barrier. All writes of
+ * non-NULL values to heap addresses should go through an entry in
+ * WriteBarrier, and from there to here.
+ *
+ * The heap is divided into "cards" of GC_CARD_SIZE bytes, as
+ * determined by GC_CARD_SHIFT. The card table contains one byte of
+ * data per card, to be used by the GC. The value of the byte will be
+ * one of GC_CARD_CLEAN or GC_CARD_DIRTY.
+ *
+ * After any store of a non-NULL object pointer into a heap object,
+ * code is obliged to mark the card dirty. The setters in
+ * object.h [such as SetFieldObject] do this for you. The
+ * compiler also contains code to mark cards as dirty.
+ *
+ * The card table's base [the "biased card table"] gets set to a
+ * rather strange value.  In order to keep the JIT from having to
+ * fabricate or load GC_DIRTY_CARD to store into the card table,
+ * biased base is within the mmap allocation at a point where its low
+ * byte is equal to GC_DIRTY_CARD. See CardTable::Create for details.
+ */
+
+CardTable* CardTable::Create(const byte* heap_begin, size_t heap_capacity) {
+  /* Set up the card table */
+  size_t capacity = heap_capacity / kCardSize;
+  /* Allocate an extra 256 bytes to allow fixed low-byte of base */
+  UniquePtr<MemMap> mem_map(MemMap::MapAnonymous("card table", NULL,
+                                                 capacity + 256, PROT_READ | PROT_WRITE));
+  CHECK(mem_map.get() != NULL) << "couldn't allocate card table";
+  // All zeros is the correct initial value; all clean. Anonymous mmaps are initialized to zero, we
+  // don't clear the card table to avoid unnecessary pages being allocated
+  COMPILE_ASSERT(kCardClean == 0, card_clean_must_be_0);
+
+  byte* cardtable_begin = mem_map->Begin();
+  CHECK(cardtable_begin != NULL);
+
+  // We allocated up to a bytes worth of extra space to allow biased_begin's byte value to equal
+  // GC_CARD_DIRTY, compute a offset value to make this the case
+  size_t offset = 0;
+  byte* biased_begin = reinterpret_cast<byte*>(reinterpret_cast<uintptr_t>(cardtable_begin) -
+      (reinterpret_cast<uintptr_t>(heap_begin) >> kCardShift));
+  if (((uintptr_t)biased_begin & 0xff) != kCardDirty) {
+    int delta = kCardDirty - (reinterpret_cast<int>(biased_begin) & 0xff);
+    offset = delta + (delta < 0 ? 0x100 : 0);
+    biased_begin += offset;
+  }
+  CHECK_EQ(reinterpret_cast<int>(biased_begin) & 0xff, kCardDirty);
+
+  return new CardTable(mem_map.release(), biased_begin, offset);
+}
+
+CardTable::CardTable(MemMap* mem_map, byte* biased_begin, size_t offset)
+    : mem_map_(mem_map), biased_begin_(biased_begin), offset_(offset) {
+  byte* __attribute__((unused)) begin = mem_map_->Begin() + offset_;
+  byte* __attribute__((unused)) end = mem_map_->End();
+}
+
+void CardTable::ClearSpaceCards(space::ContinuousSpace* space) {
+  // TODO: clear just the range of the table that has been modified
+  byte* card_start = CardFromAddr(space->Begin());
+  byte* card_end = CardFromAddr(space->End()); // Make sure to round up.
+  memset(reinterpret_cast<void*>(card_start), kCardClean, card_end - card_start);
+}
+
+void CardTable::ClearCardTable() {
+  // TODO: clear just the range of the table that has been modified
+  memset(mem_map_->Begin(), kCardClean, mem_map_->Size());
+}
+
+bool CardTable::AddrIsInCardTable(const void* addr) const {
+  return IsValidCard(biased_begin_ + ((uintptr_t)addr >> kCardShift));
+}
+
+void CardTable::CheckAddrIsInCardTable(const byte* addr) const {
+  byte* card_addr = biased_begin_ + ((uintptr_t)addr >> kCardShift);
+  byte* begin = mem_map_->Begin() + offset_;
+  byte* end = mem_map_->End();
+  CHECK(AddrIsInCardTable(addr))
+      << "Card table " << this
+      << " begin: " << reinterpret_cast<void*>(begin)
+      << " end: " << reinterpret_cast<void*>(end)
+      << " card_addr: " << reinterpret_cast<void*>(card_addr)
+      << " heap begin: " << AddrFromCard(begin)
+      << " heap end: " << AddrFromCard(end)
+      << " addr: " << reinterpret_cast<const void*>(addr);
+}
+
+void CardTable::VerifyCardTable() {
+  UNIMPLEMENTED(WARNING) << "Card table verification";
+}
+
+}  // namespace accounting
+}  // namespace gc
+}  // namespace art