ikan Uploader :
Directory : /home/ubuntu/node-v16.18.1/deps/v8/src/heap/
Upload File : |
| Current File : //home/ubuntu/node-v16.18.1/deps/v8/src/heap/read-only-spaces.cc |
// Copyright 2020 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/heap/read-only-spaces.h"
#include <memory>
#include "include/v8-internal.h"
#include "include/v8-platform.h"
#include "src/base/logging.h"
#include "src/common/globals.h"
#include "src/common/ptr-compr-inl.h"
#include "src/execution/isolate.h"
#include "src/heap/allocation-stats.h"
#include "src/heap/basic-memory-chunk.h"
#include "src/heap/combined-heap.h"
#include "src/heap/heap-inl.h"
#include "src/heap/memory-allocator.h"
#include "src/heap/memory-chunk.h"
#include "src/heap/read-only-heap.h"
#include "src/objects/objects-inl.h"
#include "src/objects/property-details.h"
#include "src/objects/string.h"
#include "src/snapshot/read-only-deserializer.h"
namespace v8 {
namespace internal {
void CopyAndRebaseRoots(Address* src, Address* dst, Address new_base) {
Address src_base = GetIsolateRootAddress(src[0]);
for (size_t i = 0; i < ReadOnlyHeap::kEntriesCount; ++i) {
dst[i] = src[i] - src_base + new_base;
}
}
void ReadOnlyArtifacts::set_read_only_heap(
std::unique_ptr<ReadOnlyHeap> read_only_heap) {
read_only_heap_ = std::move(read_only_heap);
}
void ReadOnlyArtifacts::InitializeChecksum(
SnapshotData* read_only_snapshot_data) {
#ifdef DEBUG
read_only_blob_checksum_ = Checksum(read_only_snapshot_data->Payload());
#endif // DEBUG
}
void ReadOnlyArtifacts::VerifyChecksum(SnapshotData* read_only_snapshot_data,
bool read_only_heap_created) {
#ifdef DEBUG
if (read_only_blob_checksum_) {
// The read-only heap was set up from a snapshot. Make sure it's the always
// the same snapshot.
uint32_t snapshot_checksum = Checksum(read_only_snapshot_data->Payload());
CHECK_WITH_MSG(snapshot_checksum,
"Attempt to create the read-only heap after already "
"creating from a snapshot.");
if (!FLAG_stress_snapshot) {
// --stress-snapshot is only intended to check how well the
// serializer/deserializer copes with unexpected objects, and is not
// intended to test whether the newly deserialized Isolate would actually
// work since it serializes a currently running Isolate, which is not
// supported. As a result, it's possible that it will create a new
// read-only snapshot that is not compatible with the original one (for
// instance due to the string table being re-ordered). Since we won't
// acutally use that new Isoalte, we're ok with any potential corruption.
// See crbug.com/1043058.
CHECK_EQ(read_only_blob_checksum_, snapshot_checksum);
}
} else {
// If there's no checksum, then that means the read-only heap objects are
// being created.
CHECK(read_only_heap_created);
}
#endif // DEBUG
}
SingleCopyReadOnlyArtifacts::~SingleCopyReadOnlyArtifacts() {
// This particular SharedReadOnlySpace should not destroy its own pages as
// TearDown requires MemoryAllocator which itself is tied to an Isolate.
shared_read_only_space_->pages_.resize(0);
for (ReadOnlyPage* chunk : pages_) {
void* chunk_address = reinterpret_cast<void*>(chunk->address());
size_t size = RoundUp(chunk->size(), page_allocator_->AllocatePageSize());
CHECK(page_allocator_->FreePages(chunk_address, size));
}
}
ReadOnlyHeap* SingleCopyReadOnlyArtifacts::GetReadOnlyHeapForIsolate(
Isolate* isolate) {
return read_only_heap();
}
void SingleCopyReadOnlyArtifacts::Initialize(Isolate* isolate,
std::vector<ReadOnlyPage*>&& pages,
const AllocationStats& stats) {
// Do not use the platform page allocator when sharing a pointer compression
// cage, as the Isolate's page allocator is a BoundedPageAllocator tied to the
// shared cage.
page_allocator_ = COMPRESS_POINTERS_IN_SHARED_CAGE_BOOL
? isolate->page_allocator()
: GetPlatformPageAllocator();
pages_ = std::move(pages);
set_accounting_stats(stats);
set_shared_read_only_space(
std::make_unique<SharedReadOnlySpace>(isolate->heap(), this));
}
void SingleCopyReadOnlyArtifacts::ReinstallReadOnlySpace(Isolate* isolate) {
isolate->heap()->ReplaceReadOnlySpace(shared_read_only_space());
}
void SingleCopyReadOnlyArtifacts::VerifyHeapAndSpaceRelationships(
Isolate* isolate) {
DCHECK_EQ(read_only_heap()->read_only_space(), shared_read_only_space());
// Confirm the Isolate is using the shared ReadOnlyHeap and ReadOnlySpace.
DCHECK_EQ(read_only_heap(), isolate->read_only_heap());
DCHECK_EQ(shared_read_only_space(), isolate->heap()->read_only_space());
}
void PointerCompressedReadOnlyArtifacts::InitializeRootsFrom(Isolate* isolate) {
auto isolate_ro_roots =
isolate->roots_table().read_only_roots_begin().location();
CopyAndRebaseRoots(isolate_ro_roots, read_only_roots_, 0);
}
void PointerCompressedReadOnlyArtifacts::InitializeRootsIn(Isolate* isolate) {
auto isolate_ro_roots =
isolate->roots_table().read_only_roots_begin().location();
CopyAndRebaseRoots(read_only_roots_, isolate_ro_roots,
isolate->isolate_root());
}
SharedReadOnlySpace* PointerCompressedReadOnlyArtifacts::CreateReadOnlySpace(
Isolate* isolate) {
AllocationStats new_stats;
new_stats.IncreaseCapacity(accounting_stats().Capacity());
std::vector<std::unique_ptr<v8::PageAllocator::SharedMemoryMapping>> mappings;
std::vector<ReadOnlyPage*> pages;
Address isolate_root = isolate->isolate_root();
for (size_t i = 0; i < pages_.size(); ++i) {
const ReadOnlyPage* page = pages_[i];
const Tagged_t offset = OffsetForPage(i);
Address new_address = isolate_root + offset;
ReadOnlyPage* new_page = nullptr;
bool success = isolate->heap()
->memory_allocator()
->data_page_allocator()
->ReserveForSharedMemoryMapping(
reinterpret_cast<void*>(new_address), page->size());
CHECK(success);
auto shared_memory = RemapPageTo(i, new_address, new_page);
// Later it's possible that this might fail, but for now on Linux this is
// not possible. When we move onto windows, it's not possible to reserve
// memory and then map into the middle of it at which point we will have to
// reserve the memory free it and then attempt to remap to it which could
// fail. At that point this will need to change.
CHECK(shared_memory);
CHECK_NOT_NULL(new_page);
new_stats.IncreaseAllocatedBytes(page->allocated_bytes(), new_page);
mappings.push_back(std::move(shared_memory));
pages.push_back(new_page);
}
auto* shared_read_only_space =
new SharedReadOnlySpace(isolate->heap(), std::move(pages),
std::move(mappings), std::move(new_stats));
return shared_read_only_space;
}
ReadOnlyHeap* PointerCompressedReadOnlyArtifacts::GetReadOnlyHeapForIsolate(
Isolate* isolate) {
DCHECK(ReadOnlyHeap::IsReadOnlySpaceShared());
InitializeRootsIn(isolate);
SharedReadOnlySpace* shared_read_only_space = CreateReadOnlySpace(isolate);
ReadOnlyHeap* read_only_heap = new ReadOnlyHeap(shared_read_only_space);
// TODO(v8:10699): The cache should just live uncompressed in
// ReadOnlyArtifacts and be decompressed on the fly.
auto original_cache = read_only_heap_->read_only_object_cache_;
auto& cache = read_only_heap->read_only_object_cache_;
Address isolate_root = isolate->isolate_root();
for (Object original_object : original_cache) {
Address original_address = original_object.ptr();
Address new_address = isolate_root + CompressTagged(original_address);
Object new_object = Object(new_address);
cache.push_back(new_object);
}
return read_only_heap;
}
std::unique_ptr<::v8::PageAllocator::SharedMemoryMapping>
PointerCompressedReadOnlyArtifacts::RemapPageTo(size_t i, Address new_address,
ReadOnlyPage*& new_page) {
std::unique_ptr<::v8::PageAllocator::SharedMemoryMapping> mapping =
shared_memory_[i]->RemapTo(reinterpret_cast<void*>(new_address));
if (mapping) {
new_page = static_cast<ReadOnlyPage*>(reinterpret_cast<void*>(new_address));
return mapping;
} else {
return {};
}
}
void PointerCompressedReadOnlyArtifacts::Initialize(
Isolate* isolate, std::vector<ReadOnlyPage*>&& pages,
const AllocationStats& stats) {
DCHECK(ReadOnlyHeap::IsReadOnlySpaceShared());
DCHECK(pages_.empty());
DCHECK(!pages.empty());
// It's not possible to copy the AllocationStats directly as the new pages
// will be mapped to different addresses.
stats_.IncreaseCapacity(stats.Capacity());
v8::PageAllocator* page_allocator = GetPlatformPageAllocator();
DCHECK(page_allocator->CanAllocateSharedPages());
for (const ReadOnlyPage* page : pages) {
size_t size = RoundUp(page->size(), page_allocator->AllocatePageSize());
// 1. Allocate some new memory for a shared copy of the page and copy the
// original contents into it. Doesn't need to be V8 page aligned, since
// we'll never use it directly.
auto shared_memory = page_allocator->AllocateSharedPages(size, page);
void* ptr = shared_memory->GetMemory();
CHECK_NOT_NULL(ptr);
// 2. Copy the contents of the original page into the shared page.
ReadOnlyPage* new_page = reinterpret_cast<ReadOnlyPage*>(ptr);
pages_.push_back(new_page);
shared_memory_.push_back(std::move(shared_memory));
// This is just CompressTagged but inlined so it will always compile.
Tagged_t compressed_address = CompressTagged(page->address());
page_offsets_.push_back(compressed_address);
// 3. Update the accounting stats so the allocated bytes are for the new
// shared page rather than the original.
stats_.IncreaseAllocatedBytes(page->allocated_bytes(), new_page);
}
InitializeRootsFrom(isolate);
set_shared_read_only_space(
std::make_unique<SharedReadOnlySpace>(isolate->heap(), this));
}
void PointerCompressedReadOnlyArtifacts::ReinstallReadOnlySpace(
Isolate* isolate) {
// We need to build a new SharedReadOnlySpace that occupies the same memory as
// the original one, so first the original space's pages must be freed.
Heap* heap = isolate->heap();
heap->read_only_space()->TearDown(heap->memory_allocator());
heap->ReplaceReadOnlySpace(CreateReadOnlySpace(heap->isolate()));
DCHECK_NE(heap->read_only_space(), shared_read_only_space());
// Also recreate the ReadOnlyHeap using the this space.
auto* ro_heap = new ReadOnlyHeap(isolate->read_only_heap(),
isolate->heap()->read_only_space());
isolate->set_read_only_heap(ro_heap);
DCHECK_NE(*isolate->roots_table().read_only_roots_begin().location(), 0);
}
void PointerCompressedReadOnlyArtifacts::VerifyHeapAndSpaceRelationships(
Isolate* isolate) {
// Confirm the canonical versions of the ReadOnlySpace/ReadOnlyHeap from the
// ReadOnlyArtifacts are not accidentally present in a real Isolate (which
// might destroy them) and the ReadOnlyHeaps and Spaces are correctly
// associated with each other.
DCHECK_NE(shared_read_only_space(), isolate->heap()->read_only_space());
DCHECK_NE(read_only_heap(), isolate->read_only_heap());
DCHECK_EQ(read_only_heap()->read_only_space(), shared_read_only_space());
DCHECK_EQ(isolate->read_only_heap()->read_only_space(),
isolate->heap()->read_only_space());
}
// -----------------------------------------------------------------------------
// ReadOnlySpace implementation
ReadOnlySpace::ReadOnlySpace(Heap* heap)
: BaseSpace(heap, RO_SPACE),
top_(kNullAddress),
limit_(kNullAddress),
is_string_padding_cleared_(heap->isolate()->initialized_from_snapshot()),
capacity_(0),
area_size_(MemoryChunkLayout::AllocatableMemoryInMemoryChunk(RO_SPACE)) {}
// Needs to be defined in the cc file to force the vtable to be emitted in
// component builds.
ReadOnlySpace::~ReadOnlySpace() = default;
void SharedReadOnlySpace::TearDown(MemoryAllocator* memory_allocator) {
// SharedReadOnlySpaces do not tear down their own pages since they are either
// freed down by the ReadOnlyArtifacts that contains them or in the case of
// pointer compression, they are freed when the SharedMemoryMappings are
// freed.
pages_.resize(0);
accounting_stats_.Clear();
}
void ReadOnlySpace::TearDown(MemoryAllocator* memory_allocator) {
for (ReadOnlyPage* chunk : pages_) {
memory_allocator->FreeReadOnlyPage(chunk);
}
pages_.resize(0);
accounting_stats_.Clear();
}
void ReadOnlySpace::DetachPagesAndAddToArtifacts(
std::shared_ptr<ReadOnlyArtifacts> artifacts) {
DCHECK(ReadOnlyHeap::IsReadOnlySpaceShared());
Heap* heap = ReadOnlySpace::heap();
// Without pointer compression in a per-Isolate cage, ReadOnlySpace pages are
// directly shared between all heaps and so must be unregistered from their
// originating allocator.
Seal(COMPRESS_POINTERS_IN_ISOLATE_CAGE_BOOL
? SealMode::kDetachFromHeap
: SealMode::kDetachFromHeapAndUnregisterMemory);
artifacts->Initialize(heap->isolate(), std::move(pages_), accounting_stats_);
}
void ReadOnlyPage::MakeHeaderRelocatable() {
heap_ = nullptr;
owner_ = nullptr;
reservation_.Reset();
}
void ReadOnlySpace::SetPermissionsForPages(MemoryAllocator* memory_allocator,
PageAllocator::Permission access) {
for (BasicMemoryChunk* chunk : pages_) {
// Read only pages don't have valid reservation object so we get proper
// page allocator manually.
v8::PageAllocator* page_allocator =
memory_allocator->page_allocator(NOT_EXECUTABLE);
CHECK(SetPermissions(page_allocator, chunk->address(), chunk->size(),
access));
}
}
// After we have booted, we have created a map which represents free space
// on the heap. If there was already a free list then the elements on it
// were created with the wrong FreeSpaceMap (normally nullptr), so we need to
// fix them.
void ReadOnlySpace::RepairFreeSpacesAfterDeserialization() {
BasicMemoryChunk::UpdateHighWaterMark(top_);
// Each page may have a small free space that is not tracked by a free list.
// Those free spaces still contain null as their map pointer.
// Overwrite them with new fillers.
for (BasicMemoryChunk* chunk : pages_) {
Address start = chunk->HighWaterMark();
Address end = chunk->area_end();
// Put a filler object in the gap between the end of the allocated objects
// and the end of the allocatable area.
if (start < end) {
heap()->CreateFillerObjectAt(start, static_cast<int>(end - start),
ClearRecordedSlots::kNo);
}
}
}
void ReadOnlySpace::ClearStringPaddingIfNeeded() {
if (V8_ENABLE_THIRD_PARTY_HEAP_BOOL) {
// TODO(v8:11641): Revisit this once third-party heap supports iteration.
return;
}
if (is_string_padding_cleared_) return;
ReadOnlyHeapObjectIterator iterator(this);
for (HeapObject o = iterator.Next(); !o.is_null(); o = iterator.Next()) {
if (o.IsSeqOneByteString()) {
SeqOneByteString::cast(o).clear_padding();
} else if (o.IsSeqTwoByteString()) {
SeqTwoByteString::cast(o).clear_padding();
}
}
is_string_padding_cleared_ = true;
}
void ReadOnlySpace::Seal(SealMode ro_mode) {
DCHECK(!is_marked_read_only_);
FreeLinearAllocationArea();
is_marked_read_only_ = true;
auto* memory_allocator = heap()->memory_allocator();
if (ro_mode != SealMode::kDoNotDetachFromHeap) {
DetachFromHeap();
for (ReadOnlyPage* p : pages_) {
if (ro_mode == SealMode::kDetachFromHeapAndUnregisterMemory) {
memory_allocator->UnregisterMemory(p);
}
if (ReadOnlyHeap::IsReadOnlySpaceShared()) {
p->MakeHeaderRelocatable();
}
}
}
SetPermissionsForPages(memory_allocator, PageAllocator::kRead);
}
void ReadOnlySpace::Unseal() {
DCHECK(is_marked_read_only_);
if (!pages_.empty()) {
SetPermissionsForPages(heap()->memory_allocator(),
PageAllocator::kReadWrite);
}
is_marked_read_only_ = false;
}
bool ReadOnlySpace::ContainsSlow(Address addr) {
BasicMemoryChunk* c = BasicMemoryChunk::FromAddress(addr);
for (BasicMemoryChunk* chunk : pages_) {
if (chunk == c) return true;
}
return false;
}
namespace {
// Only iterates over a single chunk as the chunk iteration is done externally.
class ReadOnlySpaceObjectIterator : public ObjectIterator {
public:
ReadOnlySpaceObjectIterator(Heap* heap, ReadOnlySpace* space,
BasicMemoryChunk* chunk)
: cur_addr_(kNullAddress), cur_end_(kNullAddress), space_(space) {}
// Advance to the next object, skipping free spaces and other fillers and
// skipping the special garbage section of which there is one per space.
// Returns nullptr when the iteration has ended.
HeapObject Next() override {
HeapObject next_obj = FromCurrentPage();
if (!next_obj.is_null()) return next_obj;
return HeapObject();
}
private:
HeapObject FromCurrentPage() {
while (cur_addr_ != cur_end_) {
if (cur_addr_ == space_->top() && cur_addr_ != space_->limit()) {
cur_addr_ = space_->limit();
continue;
}
HeapObject obj = HeapObject::FromAddress(cur_addr_);
const int obj_size = obj.Size();
cur_addr_ += obj_size;
DCHECK_LE(cur_addr_, cur_end_);
if (!obj.IsFreeSpaceOrFiller()) {
if (obj.IsCode()) {
DCHECK(Code::cast(obj).is_builtin());
DCHECK_CODEOBJECT_SIZE(obj_size, space_);
} else {
DCHECK_OBJECT_SIZE(obj_size);
}
return obj;
}
}
return HeapObject();
}
Address cur_addr_; // Current iteration point.
Address cur_end_; // End iteration point.
ReadOnlySpace* space_;
};
} // namespace
#ifdef VERIFY_HEAP
namespace {
class VerifyReadOnlyPointersVisitor : public VerifyPointersVisitor {
public:
explicit VerifyReadOnlyPointersVisitor(Heap* heap)
: VerifyPointersVisitor(heap) {}
protected:
void VerifyPointers(HeapObject host, MaybeObjectSlot start,
MaybeObjectSlot end) override {
if (!host.is_null()) {
CHECK(ReadOnlyHeap::Contains(host.map()));
}
VerifyPointersVisitor::VerifyPointers(host, start, end);
for (MaybeObjectSlot current = start; current < end; ++current) {
HeapObject heap_object;
if ((*current)->GetHeapObject(&heap_object)) {
CHECK(ReadOnlyHeap::Contains(heap_object));
}
}
}
};
} // namespace
void ReadOnlySpace::Verify(Isolate* isolate) {
bool allocation_pointer_found_in_space = top_ == limit_;
VerifyReadOnlyPointersVisitor visitor(isolate->heap());
for (BasicMemoryChunk* page : pages_) {
if (ReadOnlyHeap::IsReadOnlySpaceShared()) {
CHECK_NULL(page->owner());
} else {
CHECK_EQ(page->owner(), this);
}
if (page == Page::FromAllocationAreaAddress(top_)) {
allocation_pointer_found_in_space = true;
}
ReadOnlySpaceObjectIterator it(isolate->heap(), this, page);
Address end_of_previous_object = page->area_start();
Address top = page->area_end();
for (HeapObject object = it.Next(); !object.is_null(); object = it.Next()) {
CHECK(end_of_previous_object <= object.address());
Map map = object.map();
CHECK(map.IsMap());
// The object itself should look OK.
object.ObjectVerify(isolate);
// All the interior pointers should be contained in the heap.
int size = object.Size();
object.IterateBody(map, size, &visitor);
CHECK(object.address() + size <= top);
end_of_previous_object = object.address() + size;
CHECK(!object.IsExternalString());
CHECK(!object.IsJSArrayBuffer());
}
}
CHECK(allocation_pointer_found_in_space);
#ifdef DEBUG
VerifyCounters(isolate->heap());
#endif
}
#ifdef DEBUG
void ReadOnlySpace::VerifyCounters(Heap* heap) {
size_t total_capacity = 0;
size_t total_allocated = 0;
for (BasicMemoryChunk* page : pages_) {
total_capacity += page->area_size();
ReadOnlySpaceObjectIterator it(heap, this, page);
size_t real_allocated = 0;
for (HeapObject object = it.Next(); !object.is_null(); object = it.Next()) {
if (!object.IsFreeSpaceOrFiller()) {
real_allocated += object.Size();
}
}
total_allocated += page->allocated_bytes();
// The real size can be smaller than the accounted size if array trimming,
// object slack tracking happened after sweeping.
DCHECK_LE(real_allocated, accounting_stats_.AllocatedOnPage(page));
DCHECK_EQ(page->allocated_bytes(), accounting_stats_.AllocatedOnPage(page));
}
DCHECK_EQ(total_capacity, accounting_stats_.Capacity());
DCHECK_EQ(total_allocated, accounting_stats_.Size());
}
#endif // DEBUG
#endif // VERIFY_HEAP
size_t ReadOnlySpace::CommittedPhysicalMemory() {
if (!base::OS::HasLazyCommits()) return CommittedMemory();
BasicMemoryChunk::UpdateHighWaterMark(top_);
size_t size = 0;
for (auto* chunk : pages_) {
size += chunk->size();
}
return size;
}
void ReadOnlySpace::FreeLinearAllocationArea() {
// Mark the old linear allocation area with a free space map so it can be
// skipped when scanning the heap.
if (top_ == kNullAddress) {
DCHECK_EQ(kNullAddress, limit_);
return;
}
// Clear the bits in the unused black area.
ReadOnlyPage* page = pages_.back();
heap()->incremental_marking()->marking_state()->bitmap(page)->ClearRange(
page->AddressToMarkbitIndex(top_), page->AddressToMarkbitIndex(limit_));
heap()->CreateFillerObjectAt(top_, static_cast<int>(limit_ - top_),
ClearRecordedSlots::kNo);
BasicMemoryChunk::UpdateHighWaterMark(top_);
top_ = kNullAddress;
limit_ = kNullAddress;
}
void ReadOnlySpace::EnsureSpaceForAllocation(int size_in_bytes) {
if (top_ + size_in_bytes <= limit_) {
return;
}
DCHECK_GE(size_in_bytes, 0);
FreeLinearAllocationArea();
BasicMemoryChunk* chunk =
heap()->memory_allocator()->AllocateReadOnlyPage(AreaSize(), this);
capacity_ += AreaSize();
accounting_stats_.IncreaseCapacity(chunk->area_size());
AccountCommitted(chunk->size());
CHECK_NOT_NULL(chunk);
pages_.push_back(static_cast<ReadOnlyPage*>(chunk));
heap()->CreateFillerObjectAt(chunk->area_start(),
static_cast<int>(chunk->area_size()),
ClearRecordedSlots::kNo);
top_ = chunk->area_start();
limit_ = chunk->area_end();
return;
}
HeapObject ReadOnlySpace::TryAllocateLinearlyAligned(
int size_in_bytes, AllocationAlignment alignment) {
Address current_top = top_;
int filler_size = Heap::GetFillToAlign(current_top, alignment);
Address new_top = current_top + filler_size + size_in_bytes;
if (new_top > limit_) return HeapObject();
// Allocation always occurs in the last chunk for RO_SPACE.
BasicMemoryChunk* chunk = pages_.back();
int allocated_size = filler_size + size_in_bytes;
accounting_stats_.IncreaseAllocatedBytes(allocated_size, chunk);
chunk->IncreaseAllocatedBytes(allocated_size);
top_ = new_top;
if (filler_size > 0) {
return Heap::PrecedeWithFiller(ReadOnlyRoots(heap()),
HeapObject::FromAddress(current_top),
filler_size);
}
return HeapObject::FromAddress(current_top);
}
AllocationResult ReadOnlySpace::AllocateRawAligned(
int size_in_bytes, AllocationAlignment alignment) {
DCHECK(!FLAG_enable_third_party_heap);
DCHECK(!IsDetached());
int allocation_size = size_in_bytes;
HeapObject object = TryAllocateLinearlyAligned(allocation_size, alignment);
if (object.is_null()) {
// We don't know exactly how much filler we need to align until space is
// allocated, so assume the worst case.
EnsureSpaceForAllocation(allocation_size +
Heap::GetMaximumFillToAlign(alignment));
allocation_size = size_in_bytes;
object = TryAllocateLinearlyAligned(size_in_bytes, alignment);
CHECK(!object.is_null());
}
MSAN_ALLOCATED_UNINITIALIZED_MEMORY(object.address(), size_in_bytes);
return object;
}
AllocationResult ReadOnlySpace::AllocateRawUnaligned(int size_in_bytes) {
DCHECK(!IsDetached());
EnsureSpaceForAllocation(size_in_bytes);
Address current_top = top_;
Address new_top = current_top + size_in_bytes;
DCHECK_LE(new_top, limit_);
top_ = new_top;
HeapObject object = HeapObject::FromAddress(current_top);
DCHECK(!object.is_null());
MSAN_ALLOCATED_UNINITIALIZED_MEMORY(object.address(), size_in_bytes);
// Allocation always occurs in the last chunk for RO_SPACE.
BasicMemoryChunk* chunk = pages_.back();
accounting_stats_.IncreaseAllocatedBytes(size_in_bytes, chunk);
chunk->IncreaseAllocatedBytes(size_in_bytes);
return object;
}
AllocationResult ReadOnlySpace::AllocateRaw(int size_in_bytes,
AllocationAlignment alignment) {
#ifdef V8_HOST_ARCH_32_BIT
AllocationResult result = alignment != kWordAligned
? AllocateRawAligned(size_in_bytes, alignment)
: AllocateRawUnaligned(size_in_bytes);
#else
AllocationResult result = AllocateRawUnaligned(size_in_bytes);
#endif
HeapObject heap_obj;
if (!result.IsRetry() && result.To(&heap_obj)) {
DCHECK(heap()->incremental_marking()->marking_state()->IsBlack(heap_obj));
}
return result;
}
size_t ReadOnlyPage::ShrinkToHighWaterMark() {
// Shrink pages to high water mark. The water mark points either to a filler
// or the area_end.
HeapObject filler = HeapObject::FromAddress(HighWaterMark());
if (filler.address() == area_end()) return 0;
CHECK(filler.IsFreeSpaceOrFiller());
DCHECK_EQ(filler.address() + filler.Size(), area_end());
size_t unused = RoundDown(static_cast<size_t>(area_end() - filler.address()),
MemoryAllocator::GetCommitPageSize());
if (unused > 0) {
DCHECK_EQ(0u, unused % MemoryAllocator::GetCommitPageSize());
if (FLAG_trace_gc_verbose) {
PrintIsolate(heap()->isolate(), "Shrinking page %p: end %p -> %p\n",
reinterpret_cast<void*>(this),
reinterpret_cast<void*>(area_end()),
reinterpret_cast<void*>(area_end() - unused));
}
heap()->CreateFillerObjectAt(
filler.address(),
static_cast<int>(area_end() - filler.address() - unused),
ClearRecordedSlots::kNo);
heap()->memory_allocator()->PartialFreeMemory(
this, address() + size() - unused, unused, area_end() - unused);
if (filler.address() != area_end()) {
CHECK(filler.IsFreeSpaceOrFiller());
CHECK_EQ(filler.address() + filler.Size(), area_end());
}
}
return unused;
}
void ReadOnlySpace::ShrinkPages() {
if (V8_ENABLE_THIRD_PARTY_HEAP_BOOL) return;
BasicMemoryChunk::UpdateHighWaterMark(top_);
heap()->CreateFillerObjectAt(top_, static_cast<int>(limit_ - top_),
ClearRecordedSlots::kNo);
for (ReadOnlyPage* chunk : pages_) {
DCHECK(chunk->IsFlagSet(Page::NEVER_EVACUATE));
size_t unused = chunk->ShrinkToHighWaterMark();
capacity_ -= unused;
accounting_stats_.DecreaseCapacity(static_cast<intptr_t>(unused));
AccountUncommitted(unused);
}
limit_ = pages_.back()->area_end();
}
ReadOnlyPage* ReadOnlySpace::InitializePage(BasicMemoryChunk* chunk) {
ReadOnlyPage* page = reinterpret_cast<ReadOnlyPage*>(chunk);
page->allocated_bytes_ = 0;
page->SetFlag(BasicMemoryChunk::Flag::NEVER_EVACUATE);
heap()
->incremental_marking()
->non_atomic_marking_state()
->bitmap(chunk)
->MarkAllBits();
chunk->SetFlag(BasicMemoryChunk::READ_ONLY_HEAP);
return page;
}
SharedReadOnlySpace::SharedReadOnlySpace(
Heap* heap, PointerCompressedReadOnlyArtifacts* artifacts)
: SharedReadOnlySpace(heap) {
// This constructor should only be used when RO_SPACE is shared with pointer
// compression in a per-Isolate cage.
DCHECK(V8_SHARED_RO_HEAP_BOOL);
DCHECK(COMPRESS_POINTERS_BOOL);
DCHECK(COMPRESS_POINTERS_IN_ISOLATE_CAGE_BOOL);
DCHECK(ReadOnlyHeap::IsReadOnlySpaceShared());
DCHECK(!artifacts->pages().empty());
accounting_stats_.IncreaseCapacity(artifacts->accounting_stats().Capacity());
for (ReadOnlyPage* page : artifacts->pages()) {
pages_.push_back(page);
accounting_stats_.IncreaseAllocatedBytes(page->allocated_bytes(), page);
}
}
SharedReadOnlySpace::SharedReadOnlySpace(
Heap* heap, std::vector<ReadOnlyPage*>&& new_pages,
std::vector<std::unique_ptr<::v8::PageAllocator::SharedMemoryMapping>>&&
mappings,
AllocationStats&& new_stats)
: SharedReadOnlySpace(heap) {
DCHECK(V8_SHARED_RO_HEAP_BOOL);
DCHECK(COMPRESS_POINTERS_BOOL);
DCHECK(COMPRESS_POINTERS_IN_ISOLATE_CAGE_BOOL);
DCHECK(ReadOnlyHeap::IsReadOnlySpaceShared());
accounting_stats_ = std::move(new_stats);
pages_ = std::move(new_pages);
shared_memory_mappings_ = std::move(mappings);
}
SharedReadOnlySpace::SharedReadOnlySpace(Heap* heap,
SingleCopyReadOnlyArtifacts* artifacts)
: SharedReadOnlySpace(heap) {
// This constructor should only be used when RO_SPACE is shared without
// pointer compression in a per-Isolate cage.
DCHECK(V8_SHARED_RO_HEAP_BOOL);
DCHECK(!COMPRESS_POINTERS_IN_ISOLATE_CAGE_BOOL);
accounting_stats_ = artifacts->accounting_stats();
pages_ = artifacts->pages();
}
} // namespace internal
} // namespace v8
Kontol Shell Bypass