// Copyright 2017 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/wasm/wasm-code-manager.h" #include <iomanip> #include "src/base/iterator.h" #include "src/base/macros.h" #include "src/base/platform/platform.h" #include "src/base/small-vector.h" #include "src/codegen/assembler-inl.h" #include "src/codegen/macro-assembler-inl.h" #include "src/codegen/macro-assembler.h" #include "src/common/globals.h" #include "src/diagnostics/disassembler.h" #include "src/logging/counters.h" #include "src/logging/log.h" #include "src/objects/objects-inl.h" #include "src/snapshot/embedded/embedded-data.h" #include "src/utils/ostreams.h" #include "src/utils/vector.h" #include "src/wasm/compilation-environment.h" #include "src/wasm/function-compiler.h" #include "src/wasm/jump-table-assembler.h" #include "src/wasm/wasm-debug.h" #include "src/wasm/wasm-import-wrapper-cache.h" #include "src/wasm/wasm-module-sourcemap.h" #include "src/wasm/wasm-module.h" #include "src/wasm/wasm-objects-inl.h" #include "src/wasm/wasm-objects.h" #if defined(V8_OS_WIN64) #include "src/diagnostics/unwinding-info-win64.h" #endif // V8_OS_WIN64 #define TRACE_HEAP(...) \ do { \ if (FLAG_trace_wasm_native_heap) PrintF(__VA_ARGS__); \ } while (false) namespace v8 { namespace internal { namespace wasm { using trap_handler::ProtectedInstructionData; base::AddressRegion DisjointAllocationPool::Merge(base::AddressRegion region) { auto dest_it = regions_.begin(); auto dest_end = regions_.end(); // Skip over dest regions strictly before {region}. while (dest_it != dest_end && dest_it->end() < region.begin()) ++dest_it; // After last dest region: insert and done. if (dest_it == dest_end) { regions_.push_back(region); return region; } // Adjacent (from below) to dest: merge and done. if (dest_it->begin() == region.end()) { base::AddressRegion merged_region{region.begin(), region.size() + dest_it->size()}; DCHECK_EQ(merged_region.end(), dest_it->end()); *dest_it = merged_region; return merged_region; } // Before dest: insert and done. if (dest_it->begin() > region.end()) { regions_.insert(dest_it, region); return region; } // Src is adjacent from above. Merge and check whether the merged region is // now adjacent to the next region. DCHECK_EQ(dest_it->end(), region.begin()); dest_it->set_size(dest_it->size() + region.size()); DCHECK_EQ(dest_it->end(), region.end()); auto next_dest = dest_it; ++next_dest; if (next_dest != dest_end && dest_it->end() == next_dest->begin()) { dest_it->set_size(dest_it->size() + next_dest->size()); DCHECK_EQ(dest_it->end(), next_dest->end()); regions_.erase(next_dest); } return *dest_it; } base::AddressRegion DisjointAllocationPool::Allocate(size_t size) { return AllocateInRegion(size, {kNullAddress, std::numeric_limits<size_t>::max()}); } base::AddressRegion DisjointAllocationPool::AllocateInRegion( size_t size, base::AddressRegion region) { for (auto it = regions_.begin(), end = regions_.end(); it != end; ++it) { base::AddressRegion overlap = it->GetOverlap(region); if (size > overlap.size()) continue; base::AddressRegion ret{overlap.begin(), size}; if (size == it->size()) { // We use the full region --> erase the region from {regions_}. regions_.erase(it); } else if (ret.begin() == it->begin()) { // We return a region at the start --> shrink remaining region from front. *it = base::AddressRegion{it->begin() + size, it->size() - size}; } else if (ret.end() == it->end()) { // We return a region at the end --> shrink remaining region. *it = base::AddressRegion{it->begin(), it->size() - size}; } else { // We return something in the middle --> split the remaining region. regions_.insert( it, base::AddressRegion{it->begin(), ret.begin() - it->begin()}); *it = base::AddressRegion{ret.end(), it->end() - ret.end()}; } return ret; } return {}; } Address WasmCode::constant_pool() const { if (FLAG_enable_embedded_constant_pool) { if (constant_pool_offset_ < code_comments_offset_) { return instruction_start() + constant_pool_offset_; } } return kNullAddress; } Address WasmCode::handler_table() const { return instruction_start() + handler_table_offset_; } int WasmCode::handler_table_size() const { DCHECK_GE(constant_pool_offset_, handler_table_offset_); return static_cast<int>(constant_pool_offset_ - handler_table_offset_); } Address WasmCode::code_comments() const { return instruction_start() + code_comments_offset_; } int WasmCode::code_comments_size() const { DCHECK_GE(unpadded_binary_size_, code_comments_offset_); return static_cast<int>(unpadded_binary_size_ - code_comments_offset_); } void WasmCode::RegisterTrapHandlerData() { DCHECK(!has_trap_handler_index()); if (kind() != WasmCode::kFunction) return; if (protected_instructions_.empty()) return; Address base = instruction_start(); size_t size = instructions().size(); const int index = RegisterHandlerData(base, size, protected_instructions().size(), protected_instructions().begin()); // TODO(eholk): if index is negative, fail. CHECK_LE(0, index); set_trap_handler_index(index); DCHECK(has_trap_handler_index()); } bool WasmCode::ShouldBeLogged(Isolate* isolate) { // The return value is cached in {WasmEngine::IsolateData::log_codes}. Ensure // to call {WasmEngine::EnableCodeLogging} if this return value would change // for any isolate. Otherwise we might lose code events. return isolate->logger()->is_listening_to_code_events() || isolate->code_event_dispatcher()->IsListeningToCodeEvents() || isolate->is_profiling(); } void WasmCode::LogCode(Isolate* isolate) const { DCHECK(ShouldBeLogged(isolate)); if (IsAnonymous()) return; ModuleWireBytes wire_bytes(native_module()->wire_bytes()); WireBytesRef name_ref = native_module()->module()->function_names.Lookup(wire_bytes, index()); WasmName name = wire_bytes.GetNameOrNull(name_ref); const std::string& source_map_url = native_module()->module()->source_map_url; auto load_wasm_source_map = isolate->wasm_load_source_map_callback(); auto source_map = native_module()->GetWasmSourceMap(); if (!source_map && !source_map_url.empty() && load_wasm_source_map) { HandleScope scope(isolate); v8::Isolate* v8_isolate = reinterpret_cast<v8::Isolate*>(isolate); Local<v8::String> source_map_str = load_wasm_source_map(v8_isolate, source_map_url.c_str()); native_module()->SetWasmSourceMap( std::make_unique<WasmModuleSourceMap>(v8_isolate, source_map_str)); } std::string name_buffer; if (kind_ == kWasmToJsWrapper) { name_buffer = "wasm-to-js:"; size_t prefix_len = name_buffer.size(); constexpr size_t kMaxSigLength = 128; name_buffer.resize(prefix_len + kMaxSigLength); const FunctionSig* sig = native_module()->module()->functions[index_].sig; size_t sig_length = PrintSignature(VectorOf(&name_buffer[prefix_len], kMaxSigLength), sig); name_buffer.resize(prefix_len + sig_length); // If the import has a name, also append that (separated by "-"). if (!name.empty()) { name_buffer += '-'; name_buffer.append(name.begin(), name.size()); } name = VectorOf(name_buffer); } else if (name.empty()) { name_buffer.resize(32); name_buffer.resize( SNPrintF(VectorOf(&name_buffer.front(), name_buffer.size()), "wasm-function[%d]", index())); name = VectorOf(name_buffer); } PROFILE(isolate, CodeCreateEvent(CodeEventListener::FUNCTION_TAG, this, name)); if (!source_positions().empty()) { LOG_CODE_EVENT(isolate, CodeLinePosInfoRecordEvent(instruction_start(), source_positions())); } } void WasmCode::Validate() const { #ifdef DEBUG // We expect certain relocation info modes to never appear in {WasmCode} // objects or to be restricted to a small set of valid values. Hence the // iteration below does not use a mask, but visits all relocation data. for (RelocIterator it(instructions(), reloc_info(), constant_pool()); !it.done(); it.next()) { RelocInfo::Mode mode = it.rinfo()->rmode(); switch (mode) { case RelocInfo::WASM_CALL: { Address target = it.rinfo()->wasm_call_address(); WasmCode* code = native_module_->Lookup(target); CHECK_NOT_NULL(code); CHECK_EQ(WasmCode::kJumpTable, code->kind()); CHECK(code->contains(target)); break; } case RelocInfo::WASM_STUB_CALL: { Address target = it.rinfo()->wasm_stub_call_address(); WasmCode* code = native_module_->Lookup(target); CHECK_NOT_NULL(code); CHECK_EQ(WasmCode::kJumpTable, code->kind()); CHECK(code->contains(target)); break; } case RelocInfo::INTERNAL_REFERENCE: case RelocInfo::INTERNAL_REFERENCE_ENCODED: { Address target = it.rinfo()->target_internal_reference(); CHECK(contains(target)); break; } case RelocInfo::EXTERNAL_REFERENCE: case RelocInfo::CONST_POOL: case RelocInfo::VENEER_POOL: // These are OK to appear. break; default: FATAL("Unexpected mode: %d", mode); } } #endif } void WasmCode::MaybePrint(const char* name) const { // Determines whether flags want this code to be printed. if ((FLAG_print_wasm_code && kind() == kFunction) || (FLAG_print_wasm_stub_code && kind() != kFunction) || FLAG_print_code) { Print(name); } } void WasmCode::Print(const char* name) const { StdoutStream os; os << "--- WebAssembly code ---\n"; Disassemble(name, os); os << "--- End code ---\n"; } void WasmCode::Disassemble(const char* name, std::ostream& os, Address current_pc) const { if (name) os << "name: " << name << "\n"; if (!IsAnonymous()) os << "index: " << index() << "\n"; os << "kind: " << GetWasmCodeKindAsString(kind_) << "\n"; os << "compiler: " << (is_liftoff() ? "Liftoff" : "TurboFan") << "\n"; size_t padding = instructions().size() - unpadded_binary_size_; os << "Body (size = " << instructions().size() << " = " << unpadded_binary_size_ << " + " << padding << " padding)\n"; #ifdef ENABLE_DISASSEMBLER int instruction_size = unpadded_binary_size_; if (constant_pool_offset_ < instruction_size) { instruction_size = constant_pool_offset_; } if (safepoint_table_offset_ && safepoint_table_offset_ < instruction_size) { instruction_size = safepoint_table_offset_; } if (handler_table_offset_ < instruction_size) { instruction_size = handler_table_offset_; } DCHECK_LT(0, instruction_size); os << "Instructions (size = " << instruction_size << ")\n"; Disassembler::Decode(nullptr, &os, instructions().begin(), instructions().begin() + instruction_size, CodeReference(this), current_pc); os << "\n"; if (handler_table_size() > 0) { HandlerTable table(handler_table(), handler_table_size(), HandlerTable::kReturnAddressBasedEncoding); os << "Exception Handler Table (size = " << table.NumberOfReturnEntries() << "):\n"; table.HandlerTableReturnPrint(os); os << "\n"; } if (!protected_instructions_.empty()) { os << "Protected instructions:\n pc offset land pad\n"; for (auto& data : protected_instructions()) { os << std::setw(10) << std::hex << data.instr_offset << std::setw(10) << std::hex << data.landing_offset << "\n"; } os << "\n"; } if (!source_positions().empty()) { os << "Source positions:\n pc offset position\n"; for (SourcePositionTableIterator it(source_positions()); !it.done(); it.Advance()) { os << std::setw(10) << std::hex << it.code_offset() << std::dec << std::setw(10) << it.source_position().ScriptOffset() << (it.is_statement() ? " statement" : "") << "\n"; } os << "\n"; } if (safepoint_table_offset_ > 0) { SafepointTable table(instruction_start(), safepoint_table_offset_, stack_slots_); os << "Safepoints (size = " << table.size() << ")\n"; for (uint32_t i = 0; i < table.length(); i++) { uintptr_t pc_offset = table.GetPcOffset(i); os << reinterpret_cast<const void*>(instruction_start() + pc_offset); os << std::setw(6) << std::hex << pc_offset << " " << std::dec; table.PrintEntry(i, os); os << " (sp -> fp)"; SafepointEntry entry = table.GetEntry(i); if (entry.trampoline_pc() != -1) { os << " trampoline: " << std::hex << entry.trampoline_pc() << std::dec; } if (entry.has_deoptimization_index()) { os << " deopt: " << std::setw(6) << entry.deoptimization_index(); } os << "\n"; } os << "\n"; } os << "RelocInfo (size = " << reloc_info_.size() << ")\n"; for (RelocIterator it(instructions(), reloc_info(), constant_pool()); !it.done(); it.next()) { it.rinfo()->Print(nullptr, os); } os << "\n"; if (code_comments_size() > 0) { PrintCodeCommentsSection(os, code_comments(), code_comments_size()); } #endif // ENABLE_DISASSEMBLER } const char* GetWasmCodeKindAsString(WasmCode::Kind kind) { switch (kind) { case WasmCode::kFunction: return "wasm function"; case WasmCode::kWasmToCapiWrapper: return "wasm-to-capi"; case WasmCode::kWasmToJsWrapper: return "wasm-to-js"; case WasmCode::kInterpreterEntry: return "interpreter entry"; case WasmCode::kJumpTable: return "jump table"; } return "unknown kind"; } WasmCode::~WasmCode() { if (has_trap_handler_index()) { trap_handler::ReleaseHandlerData(trap_handler_index()); } } V8_WARN_UNUSED_RESULT bool WasmCode::DecRefOnPotentiallyDeadCode() { if (native_module_->engine()->AddPotentiallyDeadCode(this)) { // The code just became potentially dead. The ref count we wanted to // decrement is now transferred to the set of potentially dead code, and // will be decremented when the next GC is run. return false; } // If we reach here, the code was already potentially dead. Decrement the ref // count, and return true if it drops to zero. return DecRefOnDeadCode(); } // static void WasmCode::DecrementRefCount(Vector<WasmCode* const> code_vec) { // Decrement the ref counter of all given code objects. Keep the ones whose // ref count drops to zero. WasmEngine::DeadCodeMap dead_code; WasmEngine* engine = nullptr; for (WasmCode* code : code_vec) { if (!code->DecRef()) continue; // Remaining references. dead_code[code->native_module()].push_back(code); if (!engine) engine = code->native_module()->engine(); DCHECK_EQ(engine, code->native_module()->engine()); } DCHECK_EQ(dead_code.empty(), engine == nullptr); if (engine) engine->FreeDeadCode(dead_code); } WasmCodeAllocator::OptionalLock::~OptionalLock() { if (allocator_) allocator_->mutex_.Unlock(); } void WasmCodeAllocator::OptionalLock::Lock(WasmCodeAllocator* allocator) { DCHECK(!is_locked()); allocator_ = allocator; allocator->mutex_.Lock(); } WasmCodeAllocator::WasmCodeAllocator(WasmCodeManager* code_manager, VirtualMemory code_space, std::shared_ptr<Counters> async_counters) : code_manager_(code_manager), free_code_space_(code_space.region()), async_counters_(std::move(async_counters)) { owned_code_space_.reserve(4); owned_code_space_.emplace_back(std::move(code_space)); async_counters_->wasm_module_num_code_spaces()->AddSample(1); } WasmCodeAllocator::~WasmCodeAllocator() { code_manager_->FreeNativeModule(VectorOf(owned_code_space_), committed_code_space()); } void WasmCodeAllocator::Init(NativeModule* native_module) { DCHECK_EQ(1, owned_code_space_.size()); native_module->AddCodeSpace(owned_code_space_[0].region(), {}); } namespace { // On Windows, we cannot commit a region that straddles different reservations // of virtual memory. Because we bump-allocate, and because, if we need more // memory, we append that memory at the end of the owned_code_space_ list, we // traverse that list in reverse order to find the reservation(s) that guide how // to chunk the region to commit. #if V8_OS_WIN constexpr bool kNeedsToSplitRangeByReservations = true; #else constexpr bool kNeedsToSplitRangeByReservations = false; #endif base::SmallVector<base::AddressRegion, 1> SplitRangeByReservationsIfNeeded( base::AddressRegion range, const std::vector<VirtualMemory>& owned_code_space) { if (!kNeedsToSplitRangeByReservations) return {range}; base::SmallVector<base::AddressRegion, 1> split_ranges; size_t missing_begin = range.begin(); size_t missing_end = range.end(); for (auto& vmem : base::Reversed(owned_code_space)) { Address overlap_begin = std::max(missing_begin, vmem.address()); Address overlap_end = std::min(missing_end, vmem.end()); if (overlap_begin >= overlap_end) continue; split_ranges.emplace_back(overlap_begin, overlap_end - overlap_begin); // Opportunistically reduce the missing range. This might terminate the loop // early. if (missing_begin == overlap_begin) missing_begin = overlap_end; if (missing_end == overlap_end) missing_end = overlap_begin; if (missing_begin >= missing_end) break; } #ifdef ENABLE_SLOW_DCHECKS // The returned vector should cover the full range. size_t total_split_size = 0; for (auto split : split_ranges) total_split_size += split.size(); DCHECK_EQ(range.size(), total_split_size); #endif return split_ranges; } int NumWasmFunctionsInFarJumpTable(uint32_t num_declared_functions) { return NativeModule::kNeedsFarJumpsBetweenCodeSpaces ? static_cast<int>(num_declared_functions) : 0; } // Returns an overapproximation of the code size overhead per new code space // created by the jump tables. size_t OverheadPerCodeSpace(uint32_t num_declared_functions) { // Overhead for the jump table. size_t overhead = RoundUp<kCodeAlignment>( JumpTableAssembler::SizeForNumberOfSlots(num_declared_functions)); #if defined(V8_OS_WIN64) // On Win64, we need to reserve some pages at the beginning of an executable // space. See {AddCodeSpace}. overhead += Heap::GetCodeRangeReservedAreaSize(); #endif // V8_OS_WIN64 // Overhead for the far jump table. overhead += RoundUp<kCodeAlignment>(JumpTableAssembler::SizeForNumberOfFarJumpSlots( WasmCode::kRuntimeStubCount, NumWasmFunctionsInFarJumpTable(num_declared_functions))); return overhead; } size_t ReservationSize(size_t code_size_estimate, int num_declared_functions, size_t total_reserved) { size_t overhead = OverheadPerCodeSpace(num_declared_functions); // Reserve a power of two at least as big as any of // a) needed size + overhead (this is the minimum needed) // b) 2 * overhead (to not waste too much space by overhead) // c) 1/4 of current total reservation size (to grow exponentially) size_t reserve_size = base::bits::RoundUpToPowerOfTwo( std::max(std::max(RoundUp<kCodeAlignment>(code_size_estimate) + overhead, 2 * overhead), total_reserved / 4)); // Limit by the maximum supported code space size. return std::min(kMaxWasmCodeSpaceSize, reserve_size); } } // namespace Vector<byte> WasmCodeAllocator::AllocateForCode(NativeModule* native_module, size_t size) { return AllocateForCodeInRegion( native_module, size, {kNullAddress, std::numeric_limits<size_t>::max()}, WasmCodeAllocator::OptionalLock{}); } Vector<byte> WasmCodeAllocator::AllocateForCodeInRegion( NativeModule* native_module, size_t size, base::AddressRegion region, const WasmCodeAllocator::OptionalLock& optional_lock) { OptionalLock new_lock; if (!optional_lock.is_locked()) new_lock.Lock(this); const auto& locked_lock = optional_lock.is_locked() ? optional_lock : new_lock; DCHECK(locked_lock.is_locked()); DCHECK_EQ(code_manager_, native_module->engine()->code_manager()); DCHECK_LT(0, size); v8::PageAllocator* page_allocator = GetPlatformPageAllocator(); size = RoundUp<kCodeAlignment>(size); base::AddressRegion code_space = free_code_space_.AllocateInRegion(size, region); if (code_space.is_empty()) { if (region.size() < std::numeric_limits<size_t>::max()) { V8::FatalProcessOutOfMemory(nullptr, "wasm code reservation in region"); UNREACHABLE(); } Address hint = owned_code_space_.empty() ? kNullAddress : owned_code_space_.back().end(); size_t total_reserved = 0; for (auto& vmem : owned_code_space_) total_reserved += vmem.size(); size_t reserve_size = ReservationSize( size, native_module->module()->num_declared_functions, total_reserved); VirtualMemory new_mem = code_manager_->TryAllocate(reserve_size, reinterpret_cast<void*>(hint)); if (!new_mem.IsReserved()) { V8::FatalProcessOutOfMemory(nullptr, "wasm code reservation"); UNREACHABLE(); } base::AddressRegion new_region = new_mem.region(); code_manager_->AssignRange(new_region, native_module); free_code_space_.Merge(new_region); owned_code_space_.emplace_back(std::move(new_mem)); native_module->AddCodeSpace(new_region, locked_lock); code_space = free_code_space_.Allocate(size); DCHECK(!code_space.is_empty()); async_counters_->wasm_module_num_code_spaces()->AddSample( static_cast<int>(owned_code_space_.size())); } const Address commit_page_size = page_allocator->CommitPageSize(); Address commit_start = RoundUp(code_space.begin(), commit_page_size); Address commit_end = RoundUp(code_space.end(), commit_page_size); // {commit_start} will be either code_space.start or the start of the next // page. {commit_end} will be the start of the page after the one in which // the allocation ends. // We start from an aligned start, and we know we allocated vmem in // page multiples. // We just need to commit what's not committed. The page in which we // start is already committed (or we start at the beginning of a page). // The end needs to be committed all through the end of the page. if (commit_start < commit_end) { committed_code_space_.fetch_add(commit_end - commit_start); // Committed code cannot grow bigger than maximum code space size. DCHECK_LE(committed_code_space_.load(), kMaxWasmCodeMemory); for (base::AddressRegion split_range : SplitRangeByReservationsIfNeeded( {commit_start, commit_end - commit_start}, owned_code_space_)) { if (!code_manager_->Commit(split_range)) { V8::FatalProcessOutOfMemory(nullptr, "wasm code commit"); UNREACHABLE(); } } } DCHECK(IsAligned(code_space.begin(), kCodeAlignment)); allocated_code_space_.Merge(code_space); generated_code_size_.fetch_add(code_space.size(), std::memory_order_relaxed); TRACE_HEAP("Code alloc for %p: 0x%" PRIxPTR ",+%zu\n", this, code_space.begin(), size); return {reinterpret_cast<byte*>(code_space.begin()), code_space.size()}; } bool WasmCodeAllocator::SetExecutable(bool executable) { base::MutexGuard lock(&mutex_); if (is_executable_ == executable) return true; TRACE_HEAP("Setting module %p as executable: %d.\n", this, executable); v8::PageAllocator* page_allocator = GetPlatformPageAllocator(); if (FLAG_wasm_write_protect_code_memory) { PageAllocator::Permission permission = executable ? PageAllocator::kReadExecute : PageAllocator::kReadWrite; #if V8_OS_WIN // On windows, we need to switch permissions per separate virtual memory // reservation. // For now, in that case, we commit at reserved memory granularity. // Technically, that may be a waste, because we may reserve more than we // use. On 32-bit though, the scarce resource is the address space - // committed or not. for (auto& vmem : owned_code_space_) { if (!SetPermissions(page_allocator, vmem.address(), vmem.size(), permission)) { return false; } TRACE_HEAP("Set %p:%p to executable:%d\n", vmem.address(), vmem.end(), executable); } #else // V8_OS_WIN size_t commit_page_size = page_allocator->CommitPageSize(); for (auto& region : allocated_code_space_.regions()) { // allocated_code_space_ is fine-grained, so we need to // page-align it. size_t region_size = RoundUp(region.size(), commit_page_size); if (!SetPermissions(page_allocator, region.begin(), region_size, permission)) { return false; } TRACE_HEAP("Set 0x%" PRIxPTR ":0x%" PRIxPTR " to executable:%d\n", region.begin(), region.end(), executable); } #endif // V8_OS_WIN } is_executable_ = executable; return true; } void WasmCodeAllocator::FreeCode(Vector<WasmCode* const> codes) { // Zap code area and collect freed code regions. DisjointAllocationPool freed_regions; size_t code_size = 0; for (WasmCode* code : codes) { ZapCode(code->instruction_start(), code->instructions().size()); FlushInstructionCache(code->instruction_start(), code->instructions().size()); code_size += code->instructions().size(); freed_regions.Merge(base::AddressRegion{code->instruction_start(), code->instructions().size()}); } freed_code_size_.fetch_add(code_size); // Merge {freed_regions} into {freed_code_space_} and discard full pages. base::MutexGuard guard(&mutex_); PageAllocator* allocator = GetPlatformPageAllocator(); size_t commit_page_size = allocator->CommitPageSize(); for (auto region : freed_regions.regions()) { auto merged_region = freed_code_space_.Merge(region); Address discard_start = std::max(RoundUp(merged_region.begin(), commit_page_size), RoundDown(region.begin(), commit_page_size)); Address discard_end = std::min(RoundDown(merged_region.end(), commit_page_size), RoundUp(region.end(), commit_page_size)); if (discard_start >= discard_end) continue; size_t discard_size = discard_end - discard_start; size_t old_committed = committed_code_space_.fetch_sub(discard_size); DCHECK_GE(old_committed, discard_size); USE(old_committed); for (base::AddressRegion split_range : SplitRangeByReservationsIfNeeded( {discard_start, discard_size}, owned_code_space_)) { code_manager_->Decommit(split_range); } } } size_t WasmCodeAllocator::GetNumCodeSpaces() const { base::MutexGuard lock(&mutex_); return owned_code_space_.size(); } NativeModule::NativeModule(WasmEngine* engine, const WasmFeatures& enabled, VirtualMemory code_space, std::shared_ptr<const WasmModule> module, std::shared_ptr<Counters> async_counters, std::shared_ptr<NativeModule>* shared_this) : code_allocator_(engine->code_manager(), std::move(code_space), async_counters), enabled_features_(enabled), module_(std::move(module)), import_wrapper_cache_(std::unique_ptr<WasmImportWrapperCache>( new WasmImportWrapperCache())), engine_(engine), use_trap_handler_(trap_handler::IsTrapHandlerEnabled() ? kUseTrapHandler : kNoTrapHandler) { // We receive a pointer to an empty {std::shared_ptr}, and install ourselve // there. DCHECK_NOT_NULL(shared_this); DCHECK_NULL(*shared_this); shared_this->reset(this); compilation_state_ = CompilationState::New(*shared_this, std::move(async_counters)); DCHECK_NOT_NULL(module_); if (module_->num_declared_functions > 0) { code_table_ = std::make_unique<WasmCode*[]>(module_->num_declared_functions); } code_allocator_.Init(this); } void NativeModule::ReserveCodeTableForTesting(uint32_t max_functions) { WasmCodeRefScope code_ref_scope; DCHECK_LE(module_->num_declared_functions, max_functions); auto new_table = std::make_unique<WasmCode*[]>(max_functions); if (module_->num_declared_functions > 0) { memcpy(new_table.get(), code_table_.get(), module_->num_declared_functions * sizeof(WasmCode*)); } code_table_ = std::move(new_table); base::AddressRegion single_code_space_region; { base::MutexGuard guard(&allocation_mutex_); CHECK_EQ(1, code_space_data_.size()); single_code_space_region = code_space_data_[0].region; } // Re-allocate jump table. main_jump_table_ = CreateEmptyJumpTableInRegion( JumpTableAssembler::SizeForNumberOfSlots(max_functions), single_code_space_region, WasmCodeAllocator::OptionalLock{}); base::MutexGuard guard(&allocation_mutex_); code_space_data_[0].jump_table = main_jump_table_; } void NativeModule::LogWasmCodes(Isolate* isolate) { if (!WasmCode::ShouldBeLogged(isolate)) return; // TODO(titzer): we skip the logging of the import wrappers // here, but they should be included somehow. int start = module()->num_imported_functions; int end = start + module()->num_declared_functions; WasmCodeRefScope code_ref_scope; for (int func_index = start; func_index < end; ++func_index) { if (WasmCode* code = GetCode(func_index)) code->LogCode(isolate); } } CompilationEnv NativeModule::CreateCompilationEnv() const { // Protect concurrent accesses to {tier_down_}. base::MutexGuard guard(&allocation_mutex_); return {module(), use_trap_handler_, kRuntimeExceptionSupport, enabled_features_, kNoLowerSimd, tier_down_}; } WasmCode* NativeModule::AddCodeForTesting(Handle<Code> code) { // For off-heap builtins, we create a copy of the off-heap instruction stream // instead of the on-heap code object containing the trampoline. Ensure that // we do not apply the on-heap reloc info to the off-heap instructions. const size_t relocation_size = code->is_off_heap_trampoline() ? 0 : code->relocation_size(); OwnedVector<byte> reloc_info; if (relocation_size > 0) { reloc_info = OwnedVector<byte>::New(relocation_size); memcpy(reloc_info.start(), code->relocation_start(), relocation_size); } Handle<ByteArray> source_pos_table(code->SourcePositionTable(), code->GetIsolate()); OwnedVector<byte> source_pos = OwnedVector<byte>::New(source_pos_table->length()); if (source_pos_table->length() > 0) { source_pos_table->copy_out(0, source_pos.start(), source_pos_table->length()); } Vector<const byte> instructions( reinterpret_cast<byte*>(code->InstructionStart()), static_cast<size_t>(code->InstructionSize())); const int stack_slots = code->has_safepoint_info() ? code->stack_slots() : 0; // TODO(jgruber,v8:8758): Remove this translation. It exists only because // Code objects contains real offsets but WasmCode expects an offset of 0 to // mean 'empty'. const int safepoint_table_offset = code->has_safepoint_table() ? code->safepoint_table_offset() : 0; const int handler_table_offset = code->handler_table_offset(); const int constant_pool_offset = code->constant_pool_offset(); const int code_comments_offset = code->code_comments_offset(); Vector<uint8_t> dst_code_bytes = code_allocator_.AllocateForCode(this, instructions.size()); memcpy(dst_code_bytes.begin(), instructions.begin(), instructions.size()); // Apply the relocation delta by iterating over the RelocInfo. intptr_t delta = reinterpret_cast<Address>(dst_code_bytes.begin()) - code->InstructionStart(); int mode_mask = RelocInfo::kApplyMask | RelocInfo::ModeMask(RelocInfo::WASM_STUB_CALL); auto jump_tables_ref = FindJumpTablesForRegion(base::AddressRegionOf(dst_code_bytes)); Address dst_code_addr = reinterpret_cast<Address>(dst_code_bytes.begin()); Address constant_pool_start = dst_code_addr + constant_pool_offset; RelocIterator orig_it(*code, mode_mask); for (RelocIterator it(dst_code_bytes, reloc_info.as_vector(), constant_pool_start, mode_mask); !it.done(); it.next(), orig_it.next()) { RelocInfo::Mode mode = it.rinfo()->rmode(); if (RelocInfo::IsWasmStubCall(mode)) { uint32_t stub_call_tag = orig_it.rinfo()->wasm_call_tag(); DCHECK_LT(stub_call_tag, WasmCode::kRuntimeStubCount); Address entry = GetNearRuntimeStubEntry( static_cast<WasmCode::RuntimeStubId>(stub_call_tag), jump_tables_ref); it.rinfo()->set_wasm_stub_call_address(entry, SKIP_ICACHE_FLUSH); } else { it.rinfo()->apply(delta); } } // Flush the i-cache after relocation. FlushInstructionCache(dst_code_bytes.begin(), dst_code_bytes.size()); std::unique_ptr<WasmCode> new_code{new WasmCode{ this, // native_module kAnonymousFuncIndex, // index dst_code_bytes, // instructions stack_slots, // stack_slots 0, // tagged_parameter_slots safepoint_table_offset, // safepoint_table_offset handler_table_offset, // handler_table_offset constant_pool_offset, // constant_pool_offset code_comments_offset, // code_comments_offset instructions.length(), // unpadded_binary_size OwnedVector<ProtectedInstructionData>{}, // protected_instructions std::move(reloc_info), // reloc_info std::move(source_pos), // source positions WasmCode::kFunction, // kind ExecutionTier::kNone}}; // tier new_code->MaybePrint(nullptr); new_code->Validate(); return PublishCode(std::move(new_code)); } void NativeModule::UseLazyStub(uint32_t func_index) { DCHECK_LE(module_->num_imported_functions, func_index); DCHECK_LT(func_index, module_->num_imported_functions + module_->num_declared_functions); if (!lazy_compile_table_) { uint32_t num_slots = module_->num_declared_functions; WasmCodeRefScope code_ref_scope; base::AddressRegion single_code_space_region; { base::MutexGuard guard(&allocation_mutex_); DCHECK_EQ(1, code_space_data_.size()); single_code_space_region = code_space_data_[0].region; } lazy_compile_table_ = CreateEmptyJumpTableInRegion( JumpTableAssembler::SizeForNumberOfLazyFunctions(num_slots), single_code_space_region, WasmCodeAllocator::OptionalLock{}); JumpTableAssembler::GenerateLazyCompileTable( lazy_compile_table_->instruction_start(), num_slots, module_->num_imported_functions, GetNearRuntimeStubEntry(WasmCode::kWasmCompileLazy, FindJumpTablesForRegion(base::AddressRegionOf( lazy_compile_table_->instructions())))); } // Add jump table entry for jump to the lazy compile stub. uint32_t slot_index = declared_function_index(module(), func_index); DCHECK_NULL(code_table_[slot_index]); Address lazy_compile_target = lazy_compile_table_->instruction_start() + JumpTableAssembler::LazyCompileSlotIndexToOffset(slot_index); base::MutexGuard guard(&allocation_mutex_); PatchJumpTablesLocked(slot_index, lazy_compile_target); } std::unique_ptr<WasmCode> NativeModule::AddCode( int index, const CodeDesc& desc, int stack_slots, int tagged_parameter_slots, OwnedVector<trap_handler::ProtectedInstructionData> protected_instructions, OwnedVector<const byte> source_position_table, WasmCode::Kind kind, ExecutionTier tier) { Vector<byte> code_space = code_allocator_.AllocateForCode(this, desc.instr_size); auto jump_table_ref = FindJumpTablesForRegion(base::AddressRegionOf(code_space)); return AddCodeWithCodeSpace(index, desc, stack_slots, tagged_parameter_slots, std::move(protected_instructions), std::move(source_position_table), kind, tier, code_space, jump_table_ref); } std::unique_ptr<WasmCode> NativeModule::AddCodeWithCodeSpace( int index, const CodeDesc& desc, int stack_slots, int tagged_parameter_slots, OwnedVector<ProtectedInstructionData> protected_instructions, OwnedVector<const byte> source_position_table, WasmCode::Kind kind, ExecutionTier tier, Vector<uint8_t> dst_code_bytes, const JumpTablesRef& jump_tables) { OwnedVector<byte> reloc_info; if (desc.reloc_size > 0) { reloc_info = OwnedVector<byte>::New(desc.reloc_size); memcpy(reloc_info.start(), desc.buffer + desc.buffer_size - desc.reloc_size, desc.reloc_size); } // TODO(jgruber,v8:8758): Remove this translation. It exists only because // CodeDesc contains real offsets but WasmCode expects an offset of 0 to mean // 'empty'. const int safepoint_table_offset = desc.safepoint_table_size == 0 ? 0 : desc.safepoint_table_offset; const int handler_table_offset = desc.handler_table_offset; const int constant_pool_offset = desc.constant_pool_offset; const int code_comments_offset = desc.code_comments_offset; const int instr_size = desc.instr_size; memcpy(dst_code_bytes.begin(), desc.buffer, static_cast<size_t>(desc.instr_size)); // Apply the relocation delta by iterating over the RelocInfo. intptr_t delta = dst_code_bytes.begin() - desc.buffer; int mode_mask = RelocInfo::kApplyMask | RelocInfo::ModeMask(RelocInfo::WASM_CALL) | RelocInfo::ModeMask(RelocInfo::WASM_STUB_CALL); Address code_start = reinterpret_cast<Address>(dst_code_bytes.begin()); Address constant_pool_start = code_start + constant_pool_offset; for (RelocIterator it(dst_code_bytes, reloc_info.as_vector(), constant_pool_start, mode_mask); !it.done(); it.next()) { RelocInfo::Mode mode = it.rinfo()->rmode(); if (RelocInfo::IsWasmCall(mode)) { uint32_t call_tag = it.rinfo()->wasm_call_tag(); Address target = GetNearCallTargetForFunction(call_tag, jump_tables); it.rinfo()->set_wasm_call_address(target, SKIP_ICACHE_FLUSH); } else if (RelocInfo::IsWasmStubCall(mode)) { uint32_t stub_call_tag = it.rinfo()->wasm_call_tag(); DCHECK_LT(stub_call_tag, WasmCode::kRuntimeStubCount); Address entry = GetNearRuntimeStubEntry( static_cast<WasmCode::RuntimeStubId>(stub_call_tag), jump_tables); it.rinfo()->set_wasm_stub_call_address(entry, SKIP_ICACHE_FLUSH); } else { it.rinfo()->apply(delta); } } // Flush the i-cache after relocation. FlushInstructionCache(dst_code_bytes.begin(), dst_code_bytes.size()); std::unique_ptr<WasmCode> code{new WasmCode{ this, index, dst_code_bytes, stack_slots, tagged_parameter_slots, safepoint_table_offset, handler_table_offset, constant_pool_offset, code_comments_offset, instr_size, std::move(protected_instructions), std::move(reloc_info), std::move(source_position_table), kind, tier}}; code->MaybePrint(); code->Validate(); return code; } WasmCode* NativeModule::PublishCode(std::unique_ptr<WasmCode> code) { base::MutexGuard lock(&allocation_mutex_); return PublishCodeLocked(std::move(code)); } WasmCode::Kind GetCodeKind(const WasmCompilationResult& result) { switch (result.kind) { case WasmCompilationResult::kWasmToJsWrapper: return WasmCode::Kind::kWasmToJsWrapper; case WasmCompilationResult::kInterpreterEntry: return WasmCode::Kind::kInterpreterEntry; case WasmCompilationResult::kFunction: return WasmCode::Kind::kFunction; default: UNREACHABLE(); } } WasmCode* NativeModule::PublishCodeLocked(std::unique_ptr<WasmCode> code) { // The caller must hold the {allocation_mutex_}, thus we fail to lock it here. DCHECK(!allocation_mutex_.TryLock()); if (!code->IsAnonymous() && code->index() >= module_->num_imported_functions) { DCHECK_LT(code->index(), num_functions()); code->RegisterTrapHandlerData(); // Assume an order of execution tiers that represents the quality of their // generated code. static_assert(ExecutionTier::kNone < ExecutionTier::kInterpreter && ExecutionTier::kInterpreter < ExecutionTier::kLiftoff && ExecutionTier::kLiftoff < ExecutionTier::kTurbofan, "Assume an order on execution tiers"); // Unless tier down to Liftoff: update code table but avoid to fall back to // less optimized code. We use the new code if it was compiled with a higher // tier. uint32_t slot_idx = declared_function_index(module(), code->index()); WasmCode* prior_code = code_table_[slot_idx]; // TODO(clemensb): Revisit this logic once tier down is fully working. const bool prefer_liftoff = tier_down_ || debug_info_; const bool update_code_table = prefer_liftoff ? !prior_code || code->tier() == ExecutionTier::kLiftoff : !prior_code || prior_code->tier() < code->tier(); if (update_code_table) { code_table_[slot_idx] = code.get(); if (prior_code) { WasmCodeRefScope::AddRef(prior_code); // The code is added to the current {WasmCodeRefScope}, hence the ref // count cannot drop to zero here. CHECK(!prior_code->DecRef()); } } // Populate optimized code to the jump table unless there is an active // redirection to the interpreter that should be preserved. DCHECK_NOT_NULL(main_jump_table_); bool update_jump_table = update_code_table && !has_interpreter_redirection(code->index()); // Ensure that interpreter entries always populate to the jump table. if (code->kind_ == WasmCode::Kind::kInterpreterEntry) { SetInterpreterRedirection(code->index()); update_jump_table = true; } if (update_jump_table) { PatchJumpTablesLocked(slot_idx, code->instruction_start()); } } WasmCodeRefScope::AddRef(code.get()); WasmCode* result = code.get(); owned_code_.emplace(result->instruction_start(), std::move(code)); return result; } WasmCode* NativeModule::AddDeserializedCode( int index, Vector<const byte> instructions, int stack_slots, int tagged_parameter_slots, int safepoint_table_offset, int handler_table_offset, int constant_pool_offset, int code_comments_offset, int unpadded_binary_size, OwnedVector<ProtectedInstructionData> protected_instructions, OwnedVector<const byte> reloc_info, OwnedVector<const byte> source_position_table, WasmCode::Kind kind, ExecutionTier tier) { Vector<uint8_t> dst_code_bytes = code_allocator_.AllocateForCode(this, instructions.size()); memcpy(dst_code_bytes.begin(), instructions.begin(), instructions.size()); std::unique_ptr<WasmCode> code{new WasmCode{ this, index, dst_code_bytes, stack_slots, tagged_parameter_slots, safepoint_table_offset, handler_table_offset, constant_pool_offset, code_comments_offset, unpadded_binary_size, std::move(protected_instructions), std::move(reloc_info), std::move(source_position_table), kind, tier}}; // Note: we do not flush the i-cache here, since the code needs to be // relocated anyway. The caller is responsible for flushing the i-cache later. return PublishCode(std::move(code)); } std::vector<WasmCode*> NativeModule::SnapshotCodeTable() const { base::MutexGuard lock(&allocation_mutex_); WasmCode** start = code_table_.get(); WasmCode** end = start + module_->num_declared_functions; return std::vector<WasmCode*>{start, end}; } WasmCode* NativeModule::GetCode(uint32_t index) const { base::MutexGuard guard(&allocation_mutex_); WasmCode* code = code_table_[declared_function_index(module(), index)]; if (code) WasmCodeRefScope::AddRef(code); return code; } bool NativeModule::HasCode(uint32_t index) const { base::MutexGuard guard(&allocation_mutex_); return code_table_[declared_function_index(module(), index)] != nullptr; } bool NativeModule::HasCodeWithTier(uint32_t index, ExecutionTier tier) const { base::MutexGuard guard(&allocation_mutex_); return code_table_[declared_function_index(module(), index)] != nullptr && code_table_[declared_function_index(module(), index)]->tier() == tier; } void NativeModule::SetWasmSourceMap( std::unique_ptr<WasmModuleSourceMap> source_map) { source_map_ = std::move(source_map); } WasmModuleSourceMap* NativeModule::GetWasmSourceMap() const { return source_map_.get(); } WasmCode* NativeModule::CreateEmptyJumpTableInRegion( int jump_table_size, base::AddressRegion region, const WasmCodeAllocator::OptionalLock& allocator_lock) { // Only call this if we really need a jump table. DCHECK_LT(0, jump_table_size); Vector<uint8_t> code_space = code_allocator_.AllocateForCodeInRegion( this, jump_table_size, region, allocator_lock); DCHECK(!code_space.empty()); ZapCode(reinterpret_cast<Address>(code_space.begin()), code_space.size()); std::unique_ptr<WasmCode> code{new WasmCode{ this, // native_module kAnonymousFuncIndex, // index code_space, // instructions 0, // stack_slots 0, // tagged_parameter_slots 0, // safepoint_table_offset jump_table_size, // handler_table_offset jump_table_size, // constant_pool_offset jump_table_size, // code_comments_offset jump_table_size, // unpadded_binary_size OwnedVector<ProtectedInstructionData>{}, // protected_instructions OwnedVector<const uint8_t>{}, // reloc_info OwnedVector<const uint8_t>{}, // source_pos WasmCode::kJumpTable, // kind ExecutionTier::kNone}}; // tier return PublishCode(std::move(code)); } void NativeModule::PatchJumpTablesLocked(uint32_t slot_index, Address target) { // The caller must hold the {allocation_mutex_}, thus we fail to lock it here. DCHECK(!allocation_mutex_.TryLock()); for (auto& code_space_data : code_space_data_) { DCHECK_IMPLIES(code_space_data.jump_table, code_space_data.far_jump_table); if (!code_space_data.jump_table) continue; PatchJumpTableLocked(code_space_data, slot_index, target); } } void NativeModule::PatchJumpTableLocked(const CodeSpaceData& code_space_data, uint32_t slot_index, Address target) { // The caller must hold the {allocation_mutex_}, thus we fail to lock it here. DCHECK(!allocation_mutex_.TryLock()); DCHECK_NOT_NULL(code_space_data.jump_table); DCHECK_NOT_NULL(code_space_data.far_jump_table); DCHECK_LT(slot_index, module_->num_declared_functions); Address jump_table_slot = code_space_data.jump_table->instruction_start() + JumpTableAssembler::JumpSlotIndexToOffset(slot_index); uint32_t far_jump_table_offset = JumpTableAssembler::FarJumpSlotIndexToOffset( WasmCode::kRuntimeStubCount + slot_index); // Only pass the far jump table start if the far jump table actually has a // slot for this function index (i.e. does not only contain runtime stubs). bool has_far_jump_slot = far_jump_table_offset < code_space_data.far_jump_table->instructions().size(); Address far_jump_table_start = code_space_data.far_jump_table->instruction_start(); Address far_jump_table_slot = has_far_jump_slot ? far_jump_table_start + far_jump_table_offset : kNullAddress; JumpTableAssembler::PatchJumpTableSlot(jump_table_slot, far_jump_table_slot, target); } void NativeModule::AddCodeSpace( base::AddressRegion region, const WasmCodeAllocator::OptionalLock& allocator_lock) { // Each code space must be at least twice as large as the overhead per code // space. Otherwise, we are wasting too much memory. DCHECK_GE(region.size(), 2 * OverheadPerCodeSpace(module()->num_declared_functions)); #if defined(V8_OS_WIN64) // On some platforms, specifically Win64, we need to reserve some pages at // the beginning of an executable space. // See src/heap/spaces.cc, MemoryAllocator::InitializeCodePageAllocator() and // https://cs.chromium.org/chromium/src/components/crash/content/app/crashpad_win.cc?rcl=fd680447881449fba2edcf0589320e7253719212&l=204 // for details. if (engine_->code_manager() ->CanRegisterUnwindInfoForNonABICompliantCodeRange()) { size_t size = Heap::GetCodeRangeReservedAreaSize(); DCHECK_LT(0, size); Vector<byte> padding = code_allocator_.AllocateForCodeInRegion( this, size, region, allocator_lock); CHECK_EQ(reinterpret_cast<Address>(padding.begin()), region.begin()); win64_unwindinfo::RegisterNonABICompliantCodeRange( reinterpret_cast<void*>(region.begin()), region.size()); } #endif // V8_OS_WIN64 WasmCodeRefScope code_ref_scope; WasmCode* jump_table = nullptr; WasmCode* far_jump_table = nullptr; const uint32_t num_wasm_functions = module_->num_declared_functions; const bool is_first_code_space = code_space_data_.empty(); // We always need a far jump table, because it contains the runtime stubs. const bool needs_far_jump_table = !FindJumpTablesForRegion(region).is_valid(); const bool needs_jump_table = num_wasm_functions > 0 && needs_far_jump_table; if (needs_jump_table) { jump_table = CreateEmptyJumpTableInRegion( JumpTableAssembler::SizeForNumberOfSlots(num_wasm_functions), region, allocator_lock); CHECK(region.contains(jump_table->instruction_start())); } if (needs_far_jump_table) { int num_function_slots = NumWasmFunctionsInFarJumpTable(num_wasm_functions); far_jump_table = CreateEmptyJumpTableInRegion( JumpTableAssembler::SizeForNumberOfFarJumpSlots( WasmCode::kRuntimeStubCount, NumWasmFunctionsInFarJumpTable(num_function_slots)), region, allocator_lock); CHECK(region.contains(far_jump_table->instruction_start())); EmbeddedData embedded_data = EmbeddedData::FromBlob(); #define RUNTIME_STUB(Name) Builtins::k##Name, #define RUNTIME_STUB_TRAP(Name) RUNTIME_STUB(ThrowWasm##Name) Builtins::Name stub_names[WasmCode::kRuntimeStubCount] = { WASM_RUNTIME_STUB_LIST(RUNTIME_STUB, RUNTIME_STUB_TRAP)}; #undef RUNTIME_STUB #undef RUNTIME_STUB_TRAP Address builtin_addresses[WasmCode::kRuntimeStubCount]; for (int i = 0; i < WasmCode::kRuntimeStubCount; ++i) { Builtins::Name builtin = stub_names[i]; CHECK(embedded_data.ContainsBuiltin(builtin)); builtin_addresses[i] = embedded_data.InstructionStartOfBuiltin(builtin); } JumpTableAssembler::GenerateFarJumpTable( far_jump_table->instruction_start(), builtin_addresses, WasmCode::kRuntimeStubCount, num_function_slots); } if (is_first_code_space) main_jump_table_ = jump_table; base::MutexGuard guard(&allocation_mutex_); code_space_data_.push_back(CodeSpaceData{region, jump_table, far_jump_table}); if (jump_table && !is_first_code_space) { // Patch the new jump table(s) with existing functions. If this is the first // code space, there cannot be any functions that have been compiled yet. const CodeSpaceData& new_code_space_data = code_space_data_.back(); for (uint32_t slot_index = 0; slot_index < num_wasm_functions; ++slot_index) { if (code_table_[slot_index]) { PatchJumpTableLocked(new_code_space_data, slot_index, code_table_[slot_index]->instruction_start()); } else if (lazy_compile_table_) { Address lazy_compile_target = lazy_compile_table_->instruction_start() + JumpTableAssembler::LazyCompileSlotIndexToOffset(slot_index); PatchJumpTableLocked(new_code_space_data, slot_index, lazy_compile_target); } } } } namespace { class NativeModuleWireBytesStorage final : public WireBytesStorage { public: explicit NativeModuleWireBytesStorage( std::shared_ptr<OwnedVector<const uint8_t>> wire_bytes) : wire_bytes_(std::move(wire_bytes)) {} Vector<const uint8_t> GetCode(WireBytesRef ref) const final { return wire_bytes_->as_vector().SubVector(ref.offset(), ref.end_offset()); } private: const std::shared_ptr<OwnedVector<const uint8_t>> wire_bytes_; }; } // namespace void NativeModule::SetWireBytes(OwnedVector<const uint8_t> wire_bytes) { auto shared_wire_bytes = std::make_shared<OwnedVector<const uint8_t>>(std::move(wire_bytes)); wire_bytes_ = shared_wire_bytes; if (!shared_wire_bytes->empty()) { compilation_state_->SetWireBytesStorage( std::make_shared<NativeModuleWireBytesStorage>( std::move(shared_wire_bytes))); } } WasmCode* NativeModule::Lookup(Address pc) const { base::MutexGuard lock(&allocation_mutex_); auto iter = owned_code_.upper_bound(pc); if (iter == owned_code_.begin()) return nullptr; --iter; WasmCode* candidate = iter->second.get(); DCHECK_EQ(candidate->instruction_start(), iter->first); if (!candidate->contains(pc)) return nullptr; WasmCodeRefScope::AddRef(candidate); return candidate; } uint32_t NativeModule::GetJumpTableOffset(uint32_t func_index) const { uint32_t slot_idx = declared_function_index(module(), func_index); return JumpTableAssembler::JumpSlotIndexToOffset(slot_idx); } Address NativeModule::GetCallTargetForFunction(uint32_t func_index) const { // Return the jump table slot for that function index. DCHECK_NOT_NULL(main_jump_table_); uint32_t slot_offset = GetJumpTableOffset(func_index); DCHECK_LT(slot_offset, main_jump_table_->instructions().size()); return main_jump_table_->instruction_start() + slot_offset; } NativeModule::JumpTablesRef NativeModule::FindJumpTablesForRegion( base::AddressRegion code_region) const { auto jump_table_usable = [code_region](const WasmCode* jump_table) { Address table_start = jump_table->instruction_start(); Address table_end = table_start + jump_table->instructions().size(); // Compute the maximum distance from anywhere in the code region to anywhere // in the jump table, avoiding any underflow. size_t max_distance = std::max( code_region.end() > table_start ? code_region.end() - table_start : 0, table_end > code_region.begin() ? table_end - code_region.begin() : 0); return max_distance < kMaxWasmCodeSpaceSize; }; base::MutexGuard guard(&allocation_mutex_); for (auto& code_space_data : code_space_data_) { DCHECK_IMPLIES(code_space_data.jump_table, code_space_data.far_jump_table); if (!code_space_data.far_jump_table) continue; // Only return these jump tables if they are reachable from the whole // {code_region}. if (kNeedsFarJumpsBetweenCodeSpaces && (!jump_table_usable(code_space_data.far_jump_table) || (code_space_data.jump_table && !jump_table_usable(code_space_data.jump_table)))) { continue; } return {code_space_data.jump_table ? code_space_data.jump_table->instruction_start() : kNullAddress, code_space_data.far_jump_table->instruction_start()}; } return {}; } Address NativeModule::GetNearCallTargetForFunction( uint32_t func_index, const JumpTablesRef& jump_tables) const { DCHECK(jump_tables.is_valid()); uint32_t slot_offset = GetJumpTableOffset(func_index); return jump_tables.jump_table_start + slot_offset; } Address NativeModule::GetNearRuntimeStubEntry( WasmCode::RuntimeStubId index, const JumpTablesRef& jump_tables) const { DCHECK(jump_tables.is_valid()); auto offset = JumpTableAssembler::FarJumpSlotIndexToOffset(index); return jump_tables.far_jump_table_start + offset; } uint32_t NativeModule::GetFunctionIndexFromJumpTableSlot( Address slot_address) const { WasmCodeRefScope code_refs; WasmCode* code = Lookup(slot_address); DCHECK_NOT_NULL(code); DCHECK_EQ(WasmCode::kJumpTable, code->kind()); uint32_t slot_offset = static_cast<uint32_t>(slot_address - code->instruction_start()); uint32_t slot_idx = JumpTableAssembler::SlotOffsetToIndex(slot_offset); DCHECK_LT(slot_idx, module_->num_declared_functions); DCHECK_EQ(slot_address, code->instruction_start() + JumpTableAssembler::JumpSlotIndexToOffset(slot_idx)); return module_->num_imported_functions + slot_idx; } WasmCode::RuntimeStubId NativeModule::GetRuntimeStubId(Address target) const { base::MutexGuard guard(&allocation_mutex_); for (auto& code_space_data : code_space_data_) { if (code_space_data.far_jump_table->contains(target)) { uint32_t offset = static_cast<uint32_t>( target - code_space_data.far_jump_table->instruction_start()); uint32_t index = JumpTableAssembler::FarJumpSlotOffsetToIndex(offset); if (index >= WasmCode::kRuntimeStubCount) continue; if (JumpTableAssembler::FarJumpSlotIndexToOffset(index) != offset) { continue; } return static_cast<WasmCode::RuntimeStubId>(index); } } // Invalid address. return WasmCode::kRuntimeStubCount; } const char* NativeModule::GetRuntimeStubName(Address target) const { WasmCode::RuntimeStubId stub_id = GetRuntimeStubId(target); #define RUNTIME_STUB_NAME(Name) #Name, #define RUNTIME_STUB_NAME_TRAP(Name) "ThrowWasm" #Name, constexpr const char* runtime_stub_names[] = {WASM_RUNTIME_STUB_LIST( RUNTIME_STUB_NAME, RUNTIME_STUB_NAME_TRAP) "<unknown>"}; #undef RUNTIME_STUB_NAME #undef RUNTIME_STUB_NAME_TRAP STATIC_ASSERT(arraysize(runtime_stub_names) == WasmCode::kRuntimeStubCount + 1); DCHECK_GT(arraysize(runtime_stub_names), stub_id); return runtime_stub_names[stub_id]; } NativeModule::~NativeModule() { TRACE_HEAP("Deleting native module: %p\n", this); // Cancel all background compilation before resetting any field of the // NativeModule or freeing anything. compilation_state_->AbortCompilation(); engine_->FreeNativeModule(this); // Free the import wrapper cache before releasing the {WasmCode} objects in // {owned_code_}. The destructor of {WasmImportWrapperCache} still needs to // decrease reference counts on the {WasmCode} objects. import_wrapper_cache_.reset(); } WasmCodeManager::WasmCodeManager(size_t max_committed) : max_committed_code_space_(max_committed), critical_committed_code_space_(max_committed / 2) { DCHECK_LE(max_committed, kMaxWasmCodeMemory); } #if defined(V8_OS_WIN64) bool WasmCodeManager::CanRegisterUnwindInfoForNonABICompliantCodeRange() const { return win64_unwindinfo::CanRegisterUnwindInfoForNonABICompliantCodeRange() && FLAG_win64_unwinding_info; } #endif // V8_OS_WIN64 bool WasmCodeManager::Commit(base::AddressRegion region) { // TODO(v8:8462): Remove eager commit once perf supports remapping. if (FLAG_perf_prof) return true; DCHECK(IsAligned(region.begin(), CommitPageSize())); DCHECK(IsAligned(region.size(), CommitPageSize())); // Reserve the size. Use CAS loop to avoid overflow on // {total_committed_code_space_}. size_t old_value = total_committed_code_space_.load(); while (true) { DCHECK_GE(max_committed_code_space_, old_value); if (region.size() > max_committed_code_space_ - old_value) return false; if (total_committed_code_space_.compare_exchange_weak( old_value, old_value + region.size())) { break; } } PageAllocator::Permission permission = FLAG_wasm_write_protect_code_memory ? PageAllocator::kReadWrite : PageAllocator::kReadWriteExecute; bool ret = SetPermissions(GetPlatformPageAllocator(), region.begin(), region.size(), permission); TRACE_HEAP("Setting rw permissions for 0x%" PRIxPTR ":0x%" PRIxPTR "\n", region.begin(), region.end()); if (!ret) { // Highly unlikely. total_committed_code_space_.fetch_sub(region.size()); return false; } return true; } void WasmCodeManager::Decommit(base::AddressRegion region) { // TODO(v8:8462): Remove this once perf supports remapping. if (FLAG_perf_prof) return; PageAllocator* allocator = GetPlatformPageAllocator(); DCHECK(IsAligned(region.begin(), allocator->CommitPageSize())); DCHECK(IsAligned(region.size(), allocator->CommitPageSize())); size_t old_committed = total_committed_code_space_.fetch_sub(region.size()); DCHECK_LE(region.size(), old_committed); USE(old_committed); TRACE_HEAP("Discarding system pages 0x%" PRIxPTR ":0x%" PRIxPTR "\n", region.begin(), region.end()); CHECK(allocator->SetPermissions(reinterpret_cast<void*>(region.begin()), region.size(), PageAllocator::kNoAccess)); } void WasmCodeManager::AssignRange(base::AddressRegion region, NativeModule* native_module) { base::MutexGuard lock(&native_modules_mutex_); lookup_map_.insert(std::make_pair( region.begin(), std::make_pair(region.end(), native_module))); } VirtualMemory WasmCodeManager::TryAllocate(size_t size, void* hint) { v8::PageAllocator* page_allocator = GetPlatformPageAllocator(); DCHECK_GT(size, 0); size_t allocate_page_size = page_allocator->AllocatePageSize(); size = RoundUp(size, allocate_page_size); if (!BackingStore::ReserveAddressSpace(size)) return {}; if (hint == nullptr) hint = page_allocator->GetRandomMmapAddr(); VirtualMemory mem(page_allocator, size, hint, allocate_page_size); if (!mem.IsReserved()) { BackingStore::ReleaseReservation(size); return {}; } TRACE_HEAP("VMem alloc: 0x%" PRIxPTR ":0x%" PRIxPTR " (%zu)\n", mem.address(), mem.end(), mem.size()); // TODO(v8:8462): Remove eager commit once perf supports remapping. if (FLAG_perf_prof) { SetPermissions(GetPlatformPageAllocator(), mem.address(), mem.size(), PageAllocator::kReadWriteExecute); } return mem; } namespace { // The numbers here are rough estimates, used to calculate the size of the // initial code reservation and for estimating the amount of external memory // reported to the GC. // They do not need to be accurate. Choosing them too small will result in // separate code spaces being allocated (compile time and runtime overhead), // choosing them too large results in over-reservation (virtual address space // only). // The current numbers have been determined on 2019-11-11 by clemensb@, based // on one small and one large module compiled from C++ by Emscripten. If in // doubt, they where chosen slightly larger than required, as over-reservation // is not a big issue currently. // Numbers will change when Liftoff or TurboFan evolve, other toolchains are // used to produce the wasm code, or characteristics of wasm modules on the // web change. They might require occasional tuning. // This patch might help to find reasonable numbers for any future adaptation: // https://crrev.com/c/1910945 #if V8_TARGET_ARCH_X64 constexpr size_t kTurbofanFunctionOverhead = 20; constexpr size_t kTurbofanCodeSizeMultiplier = 3; constexpr size_t kLiftoffFunctionOverhead = 60; constexpr size_t kLiftoffCodeSizeMultiplier = 4; constexpr size_t kImportSize = 350; #elif V8_TARGET_ARCH_IA32 constexpr size_t kTurbofanFunctionOverhead = 20; constexpr size_t kTurbofanCodeSizeMultiplier = 4; constexpr size_t kLiftoffFunctionOverhead = 60; constexpr size_t kLiftoffCodeSizeMultiplier = 5; constexpr size_t kImportSize = 480; #elif V8_TARGET_ARCH_ARM constexpr size_t kTurbofanFunctionOverhead = 40; constexpr size_t kTurbofanCodeSizeMultiplier = 4; constexpr size_t kLiftoffFunctionOverhead = 108; constexpr size_t kLiftoffCodeSizeMultiplier = 7; constexpr size_t kImportSize = 750; #elif V8_TARGET_ARCH_ARM64 constexpr size_t kTurbofanFunctionOverhead = 60; constexpr size_t kTurbofanCodeSizeMultiplier = 4; constexpr size_t kLiftoffFunctionOverhead = 80; constexpr size_t kLiftoffCodeSizeMultiplier = 7; constexpr size_t kImportSize = 750; #else // Other platforms should add their own estimates if needed. Numbers below are // the minimum of other architectures. constexpr size_t kTurbofanFunctionOverhead = 20; constexpr size_t kTurbofanCodeSizeMultiplier = 3; constexpr size_t kLiftoffFunctionOverhead = 60; constexpr size_t kLiftoffCodeSizeMultiplier = 4; constexpr size_t kImportSize = 350; #endif } // namespace // static size_t WasmCodeManager::EstimateLiftoffCodeSize(int body_size) { return kLiftoffFunctionOverhead + kCodeAlignment / 2 + body_size * kLiftoffCodeSizeMultiplier; } // static size_t WasmCodeManager::EstimateNativeModuleCodeSize(const WasmModule* module, bool include_liftoff) { int num_functions = static_cast<int>(module->num_declared_functions); int num_imported_functions = static_cast<int>(module->num_imported_functions); int code_section_length = 0; if (num_functions > 0) { DCHECK_EQ(module->functions.size(), num_imported_functions + num_functions); auto* first_fn = &module->functions[module->num_imported_functions]; auto* last_fn = &module->functions.back(); code_section_length = static_cast<int>(last_fn->code.end_offset() - first_fn->code.offset()); } return EstimateNativeModuleCodeSize(num_functions, num_imported_functions, code_section_length, include_liftoff); } // static size_t WasmCodeManager::EstimateNativeModuleCodeSize(int num_functions, int num_imported_functions, int code_section_length, bool include_liftoff) { const size_t overhead_per_function = kTurbofanFunctionOverhead + kCodeAlignment / 2 + (include_liftoff ? kLiftoffFunctionOverhead + kCodeAlignment / 2 : 0); const size_t overhead_per_code_byte = kTurbofanCodeSizeMultiplier + (include_liftoff ? kLiftoffCodeSizeMultiplier : 0); const size_t jump_table_size = RoundUp<kCodeAlignment>( JumpTableAssembler::SizeForNumberOfSlots(num_functions)); const size_t far_jump_table_size = RoundUp<kCodeAlignment>(JumpTableAssembler::SizeForNumberOfFarJumpSlots( WasmCode::kRuntimeStubCount, NumWasmFunctionsInFarJumpTable(num_functions))); return jump_table_size // jump table + far_jump_table_size // far jump table + overhead_per_function * num_functions // per function + overhead_per_code_byte * code_section_length // per code byte + kImportSize * num_imported_functions; // per import } // static size_t WasmCodeManager::EstimateNativeModuleMetaDataSize( const WasmModule* module) { size_t wasm_module_estimate = EstimateStoredSize(module); uint32_t num_wasm_functions = module->num_declared_functions; // TODO(wasm): Include wire bytes size. size_t native_module_estimate = sizeof(NativeModule) + /* NativeModule struct */ (sizeof(WasmCode*) * num_wasm_functions) + /* code table size */ (sizeof(WasmCode) * num_wasm_functions); /* code object size */ return wasm_module_estimate + native_module_estimate; } std::shared_ptr<NativeModule> WasmCodeManager::NewNativeModule( WasmEngine* engine, Isolate* isolate, const WasmFeatures& enabled, size_t code_size_estimate, std::shared_ptr<const WasmModule> module) { DCHECK_EQ(this, isolate->wasm_engine()->code_manager()); if (total_committed_code_space_.load() > critical_committed_code_space_.load()) { (reinterpret_cast<v8::Isolate*>(isolate)) ->MemoryPressureNotification(MemoryPressureLevel::kCritical); size_t committed = total_committed_code_space_.load(); DCHECK_GE(max_committed_code_space_, committed); critical_committed_code_space_.store( committed + (max_committed_code_space_ - committed) / 2); } // If we cannot add code space later, reserve enough address space up front. size_t code_vmem_size = ReservationSize(code_size_estimate, module->num_declared_functions, 0); // The '--wasm-max-code-space-reservation' testing flag can be used to reduce // the maximum size of the initial code space reservation (in MB). if (FLAG_wasm_max_initial_code_space_reservation > 0) { size_t flag_max_bytes = static_cast<size_t>(FLAG_wasm_max_initial_code_space_reservation) * MB; if (flag_max_bytes < code_vmem_size) code_vmem_size = flag_max_bytes; } // Try up to two times; getting rid of dead JSArrayBuffer allocations might // require two GCs because the first GC maybe incremental and may have // floating garbage. static constexpr int kAllocationRetries = 2; VirtualMemory code_space; for (int retries = 0;; ++retries) { code_space = TryAllocate(code_vmem_size); if (code_space.IsReserved()) break; if (retries == kAllocationRetries) { V8::FatalProcessOutOfMemory(isolate, "NewNativeModule"); UNREACHABLE(); } // Run one GC, then try the allocation again. isolate->heap()->MemoryPressureNotification(MemoryPressureLevel::kCritical, true); } Address start = code_space.address(); size_t size = code_space.size(); Address end = code_space.end(); std::shared_ptr<NativeModule> ret; new NativeModule(engine, enabled, std::move(code_space), std::move(module), isolate->async_counters(), &ret); // The constructor initialized the shared_ptr. DCHECK_NOT_NULL(ret); TRACE_HEAP("New NativeModule %p: Mem: %" PRIuPTR ",+%zu\n", ret.get(), start, size); base::MutexGuard lock(&native_modules_mutex_); lookup_map_.insert(std::make_pair(start, std::make_pair(end, ret.get()))); return ret; } void NativeModule::SampleCodeSize( Counters* counters, NativeModule::CodeSamplingTime sampling_time) const { size_t code_size = sampling_time == kSampling ? code_allocator_.committed_code_space() : code_allocator_.generated_code_size(); int code_size_mb = static_cast<int>(code_size / MB); Histogram* histogram = nullptr; switch (sampling_time) { case kAfterBaseline: histogram = counters->wasm_module_code_size_mb_after_baseline(); break; case kAfterTopTier: histogram = counters->wasm_module_code_size_mb_after_top_tier(); break; case kSampling: { histogram = counters->wasm_module_code_size_mb(); // If this is a wasm module of >= 2MB, also sample the freed code size, // absolute and relative. Code GC does not happen on asm.js modules, and // small modules will never trigger GC anyway. size_t generated_size = code_allocator_.generated_code_size(); if (generated_size >= 2 * MB && module()->origin == kWasmOrigin) { size_t freed_size = code_allocator_.freed_code_size(); DCHECK_LE(freed_size, generated_size); int freed_percent = static_cast<int>(100 * freed_size / generated_size); counters->wasm_module_freed_code_size_percent()->AddSample( freed_percent); } break; } } histogram->AddSample(code_size_mb); } WasmCode* NativeModule::AddCompiledCode(WasmCompilationResult result) { return AddCompiledCode({&result, 1})[0]; } std::vector<WasmCode*> NativeModule::AddCompiledCode( Vector<WasmCompilationResult> results) { DCHECK(!results.empty()); // First, allocate code space for all the results. size_t total_code_space = 0; for (auto& result : results) { DCHECK(result.succeeded()); total_code_space += RoundUp<kCodeAlignment>(result.code_desc.instr_size); } Vector<byte> code_space = code_allocator_.AllocateForCode(this, total_code_space); // Lookup the jump tables to use once, then use for all code objects. auto jump_tables = FindJumpTablesForRegion(base::AddressRegionOf(code_space)); std::vector<std::unique_ptr<WasmCode>> generated_code; generated_code.reserve(results.size()); // Now copy the generated code into the code space and relocate it. for (auto& result : results) { DCHECK_EQ(result.code_desc.buffer, result.instr_buffer.get()); size_t code_size = RoundUp<kCodeAlignment>(result.code_desc.instr_size); Vector<byte> this_code_space = code_space.SubVector(0, code_size); code_space += code_size; generated_code.emplace_back(AddCodeWithCodeSpace( result.func_index, result.code_desc, result.frame_slot_count, result.tagged_parameter_slots, std::move(result.protected_instructions), std::move(result.source_positions), GetCodeKind(result), result.result_tier, this_code_space, jump_tables)); } DCHECK_EQ(0, code_space.size()); // Under the {allocation_mutex_}, publish the code. The published code is put // into the top-most surrounding {WasmCodeRefScope} by {PublishCodeLocked}. std::vector<WasmCode*> code_vector; code_vector.reserve(results.size()); { base::MutexGuard lock(&allocation_mutex_); for (auto& result : generated_code) code_vector.push_back(PublishCodeLocked(std::move(result))); } return code_vector; } bool NativeModule::IsRedirectedToInterpreter(uint32_t func_index) { base::MutexGuard lock(&allocation_mutex_); return has_interpreter_redirection(func_index); } bool NativeModule::SetTieredDown() { // Do not tier down asm.js. if (module()->origin != kWasmOrigin) return false; base::MutexGuard lock(&allocation_mutex_); if (tier_down_) return true; tier_down_ = true; return false; } bool NativeModule::IsTieredDown() { base::MutexGuard lock(&allocation_mutex_); return tier_down_; } void NativeModule::TierDown(Isolate* isolate) { // Do not tier down asm.js. if (module()->origin != kWasmOrigin) return; // Set the flag. Return if it is already set. if (SetTieredDown()) return; // Tier down all functions. isolate->wasm_engine()->RecompileAllFunctions(isolate, this, ExecutionTier::kLiftoff); } void NativeModule::TierUp(Isolate* isolate) { // Do not tier up asm.js. if (module()->origin != kWasmOrigin) return; // Set the flag. { base::MutexGuard lock(&allocation_mutex_); tier_down_ = false; } // Tier up all functions. isolate->wasm_engine()->RecompileAllFunctions(isolate, this, ExecutionTier::kTurbofan); } void NativeModule::FreeCode(Vector<WasmCode* const> codes) { // Free the code space. code_allocator_.FreeCode(codes); base::MutexGuard guard(&allocation_mutex_); // Remove debug side tables for all removed code objects. if (debug_info_) debug_info_->RemoveDebugSideTables(codes); // Free the {WasmCode} objects. This will also unregister trap handler data. for (WasmCode* code : codes) { DCHECK_EQ(1, owned_code_.count(code->instruction_start())); owned_code_.erase(code->instruction_start()); } } size_t NativeModule::GetNumberOfCodeSpacesForTesting() const { return code_allocator_.GetNumCodeSpaces(); } DebugInfo* NativeModule::GetDebugInfo() { base::MutexGuard guard(&allocation_mutex_); if (!debug_info_) debug_info_ = std::make_unique<DebugInfo>(this); return debug_info_.get(); } void WasmCodeManager::FreeNativeModule(Vector<VirtualMemory> owned_code_space, size_t committed_size) { base::MutexGuard lock(&native_modules_mutex_); for (auto& code_space : owned_code_space) { DCHECK(code_space.IsReserved()); TRACE_HEAP("VMem Release: 0x%" PRIxPTR ":0x%" PRIxPTR " (%zu)\n", code_space.address(), code_space.end(), code_space.size()); #if defined(V8_OS_WIN64) if (CanRegisterUnwindInfoForNonABICompliantCodeRange()) { win64_unwindinfo::UnregisterNonABICompliantCodeRange( reinterpret_cast<void*>(code_space.address())); } #endif // V8_OS_WIN64 lookup_map_.erase(code_space.address()); BackingStore::ReleaseReservation(code_space.size()); code_space.Free(); DCHECK(!code_space.IsReserved()); } DCHECK(IsAligned(committed_size, CommitPageSize())); // TODO(v8:8462): Remove this once perf supports remapping. if (!FLAG_perf_prof) { size_t old_committed = total_committed_code_space_.fetch_sub(committed_size); DCHECK_LE(committed_size, old_committed); USE(old_committed); } } NativeModule* WasmCodeManager::LookupNativeModule(Address pc) const { base::MutexGuard lock(&native_modules_mutex_); if (lookup_map_.empty()) return nullptr; auto iter = lookup_map_.upper_bound(pc); if (iter == lookup_map_.begin()) return nullptr; --iter; Address region_start = iter->first; Address region_end = iter->second.first; NativeModule* candidate = iter->second.second; DCHECK_NOT_NULL(candidate); return region_start <= pc && pc < region_end ? candidate : nullptr; } WasmCode* WasmCodeManager::LookupCode(Address pc) const { NativeModule* candidate = LookupNativeModule(pc); return candidate ? candidate->Lookup(pc) : nullptr; } // TODO(v8:7424): Code protection scopes are not yet supported with shared code // enabled and need to be revisited. NativeModuleModificationScope::NativeModuleModificationScope( NativeModule* native_module) : native_module_(native_module) { if (FLAG_wasm_write_protect_code_memory && native_module_ && (native_module_->modification_scope_depth_++) == 0) { bool success = native_module_->SetExecutable(false); CHECK(success); } } NativeModuleModificationScope::~NativeModuleModificationScope() { if (FLAG_wasm_write_protect_code_memory && native_module_ && (native_module_->modification_scope_depth_--) == 1) { bool success = native_module_->SetExecutable(true); CHECK(success); } } namespace { thread_local WasmCodeRefScope* current_code_refs_scope = nullptr; } // namespace WasmCodeRefScope::WasmCodeRefScope() : previous_scope_(current_code_refs_scope) { current_code_refs_scope = this; } WasmCodeRefScope::~WasmCodeRefScope() { DCHECK_EQ(this, current_code_refs_scope); current_code_refs_scope = previous_scope_; std::vector<WasmCode*> code_ptrs; code_ptrs.reserve(code_ptrs_.size()); code_ptrs.assign(code_ptrs_.begin(), code_ptrs_.end()); WasmCode::DecrementRefCount(VectorOf(code_ptrs)); } // static void WasmCodeRefScope::AddRef(WasmCode* code) { DCHECK_NOT_NULL(code); WasmCodeRefScope* current_scope = current_code_refs_scope; DCHECK_NOT_NULL(current_scope); auto entry = current_scope->code_ptrs_.insert(code); // If we added a new entry, increment the ref counter. if (entry.second) code->IncRef(); } } // namespace wasm } // namespace internal } // namespace v8 #undef TRACE_HEAP