/
wasm-code-manager.cc
2021 lines (1812 loc) · 80.6 KB
/
wasm-code-manager.cc
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// 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/build_config.h"
#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/code-space-access.h"
#include "src/wasm/compilation-environment.h"
#include "src/wasm/function-compiler.h"
#include "src/wasm/jump-table-assembler.h"
#include "src/wasm/module-compiler.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;
#if defined(V8_OS_MACOSX) && defined(V8_HOST_ARCH_ARM64)
thread_local int CodeSpaceWriteScope::code_space_write_nesting_level_ = 0;
#endif
base::AddressRegion DisjointAllocationPool::Merge(
base::AddressRegion new_region) {
// Find the possible insertion position by identifying the first region whose
// start address is not less than that of {new_region}. Since there cannot be
// any overlap between regions, this also means that the start of {above} is
// bigger or equal than the *end* of {new_region}.
auto above = regions_.lower_bound(new_region);
DCHECK(above == regions_.end() || above->begin() >= new_region.end());
// Check whether to merge with {above}.
if (above != regions_.end() && new_region.end() == above->begin()) {
base::AddressRegion merged_region{new_region.begin(),
new_region.size() + above->size()};
DCHECK_EQ(merged_region.end(), above->end());
// Check whether to also merge with the region below.
if (above != regions_.begin()) {
auto below = above;
--below;
if (below->end() == new_region.begin()) {
merged_region = {below->begin(), below->size() + merged_region.size()};
regions_.erase(below);
}
}
auto insert_pos = regions_.erase(above);
regions_.insert(insert_pos, merged_region);
return merged_region;
}
// No element below, and not adjavent to {above}: insert and done.
if (above == regions_.begin()) {
regions_.insert(above, new_region);
return new_region;
}
auto below = above;
--below;
// Sanity check:
DCHECK(above == regions_.end() || below->end() < above->begin());
// Adjacent to {below}: merge and done.
if (below->end() == new_region.begin()) {
base::AddressRegion merged_region{below->begin(),
below->size() + new_region.size()};
DCHECK_EQ(merged_region.end(), new_region.end());
regions_.erase(below);
regions_.insert(above, merged_region);
return merged_region;
}
// Not adjacent to any existing region: insert between {below} and {above}.
DCHECK_LT(below->end(), new_region.begin());
regions_.insert(above, new_region);
return new_region;
}
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) {
// Get an iterator to the first contained region whose start address is not
// smaller than the start address of {region}. Start the search from the
// region one before that (the last one whose start address is smaller).
auto it = regions_.lower_bound(region);
if (it != regions_.begin()) --it;
for (auto end = regions_.end(); it != end; ++it) {
base::AddressRegion overlap = it->GetOverlap(region);
if (size > overlap.size()) continue;
base::AddressRegion ret{overlap.begin(), size};
base::AddressRegion old = *it;
auto insert_pos = regions_.erase(it);
if (size == old.size()) {
// We use the full region --> nothing to add back.
} else if (ret.begin() == old.begin()) {
// We return a region at the start --> shrink old region from front.
regions_.insert(insert_pos, {old.begin() + size, old.size() - size});
} else if (ret.end() == old.end()) {
// We return a region at the end --> shrink remaining region.
regions_.insert(insert_pos, {old.begin(), old.size() - size});
} else {
// We return something in the middle --> split the remaining region
// (insert the region with smaller address first).
regions_.insert(insert_pos, {old.begin(), ret.begin() - old.begin()});
regions_.insert(insert_pos, {ret.end(), old.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_);
}
std::unique_ptr<const byte[]> WasmCode::ConcatenateBytes(
std::initializer_list<Vector<const byte>> vectors) {
size_t total_size = 0;
for (auto& vec : vectors) total_size += vec.size();
// Use default-initialization (== no initialization).
std::unique_ptr<byte[]> result{new byte[total_size]};
byte* ptr = result.get();
for (auto& vec : vectors) {
if (vec.empty()) continue; // Avoid nullptr in {memcpy}.
memcpy(ptr, vec.begin(), vec.size());
ptr += vec.size();
}
return result;
}
void WasmCode::RegisterTrapHandlerData() {
DCHECK(!has_trap_handler_index());
if (kind() != WasmCode::kFunction) return;
if (protected_instructions_size_ == 0) return;
Address base = instruction_start();
size_t size = instructions().size();
auto protected_instruction_data = this->protected_instructions();
const int index =
RegisterHandlerData(base, size, protected_instruction_data.size(),
protected_instruction_data.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()->lazily_generated_names.LookupFunctionName(
wire_bytes, index(),
VectorOf(native_module()->module()->export_table));
WasmName name = wire_bytes.GetNameOrNull(name_ref);
const WasmDebugSymbols& debug_symbols =
native_module()->module()->debug_symbols;
auto load_wasm_source_map = isolate->wasm_load_source_map_callback();
auto source_map = native_module()->GetWasmSourceMap();
if (!source_map && debug_symbols.type == WasmDebugSymbols::Type::SourceMap &&
!debug_symbols.external_url.is_empty() && load_wasm_source_map) {
WasmName external_url =
wire_bytes.GetNameOrNull(debug_symbols.external_url);
std::string external_url_string(external_url.data(), external_url.size());
HandleScope scope(isolate);
v8::Isolate* v8_isolate = reinterpret_cast<v8::Isolate*>(isolate);
Local<v8::String> source_map_str =
load_wasm_source_map(v8_isolate, external_url_string.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
// Scope for foreign WasmCode pointers.
WasmCodeRefScope code_ref_scope;
// 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_size_ > 0) {
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::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);
}
int WasmCode::GetSourcePositionBefore(int offset) {
int position = kNoSourcePosition;
for (SourcePositionTableIterator iterator(source_positions());
!iterator.done() && iterator.code_offset() < offset;
iterator.Advance()) {
position = iterator.source_position().ScriptOffset();
}
return position;
}
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;
CODE_SPACE_WRITE_SCOPE
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 {
return {module(), use_trap_handler_, kRuntimeExceptionSupport,
enabled_features_, kNoLowerSimd};
}
WasmCode* NativeModule::AddCodeForTesting(Handle<Code> code) {
CODE_SPACE_WRITE_SCOPE
// 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
{}, // protected_instructions
reloc_info.as_vector(), // reloc_info
source_pos.as_vector(), // source positions
WasmCode::kFunction, // kind
ExecutionTier::kNone, // tier
kNoDebugging}}; // for_debugging
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;
CODE_SPACE_WRITE_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, Vector<const byte> protected_instructions_data,
Vector<const byte> source_position_table, WasmCode::Kind kind,
ExecutionTier tier, ForDebugging for_debugging) {
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,
protected_instructions_data,
source_position_table, kind, tier, for_debugging,
code_space, jump_table_ref);
}
std::unique_ptr<WasmCode> NativeModule::AddCodeWithCodeSpace(
int index, const CodeDesc& desc, int stack_slots,
int tagged_parameter_slots, Vector<const byte> protected_instructions_data,
Vector<const byte> source_position_table, WasmCode::Kind kind,
ExecutionTier tier, ForDebugging for_debugging,
Vector<uint8_t> dst_code_bytes, const JumpTablesRef& jump_tables) {
Vector<byte> reloc_info{desc.buffer + desc.buffer_size - desc.reloc_size,
static_cast<size_t>(desc.reloc_size)};
// TODO(jgruber,v8:8758): Remove this translation. It exists only because