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- // Copyright 2013 The Chromium 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 "gin/v8_initializer.h"
- #include <stddef.h>
- #include <stdint.h>
- #include <cstdint>
- #include <memory>
- #include "base/allocator/partition_allocator/page_allocator.h"
- #include "base/allocator/partition_allocator/partition_address_space.h"
- #include "base/bits.h"
- #include "base/check.h"
- #include "base/debug/alias.h"
- #include "base/debug/crash_logging.h"
- #include "base/feature_list.h"
- #include "base/files/file.h"
- #include "base/files/file_path.h"
- #include "base/files/memory_mapped_file.h"
- #include "base/lazy_instance.h"
- #include "base/metrics/histogram_functions.h"
- #include "base/metrics/histogram_macros.h"
- #include "base/notreached.h"
- #include "base/path_service.h"
- #include "base/rand_util.h"
- #include "base/strings/string_piece.h"
- #include "base/strings/string_split.h"
- #include "base/strings/string_util.h"
- #include "base/strings/sys_string_conversions.h"
- #include "base/system/sys_info.h"
- #include "base/threading/platform_thread.h"
- #include "base/time/time.h"
- #include "build/build_config.h"
- #include "gin/array_buffer.h"
- #include "gin/gin_features.h"
- #include "third_party/abseil-cpp/absl/types/optional.h"
- #include "v8/include/v8-initialization.h"
- #include "v8/include/v8-snapshot.h"
- #if BUILDFLAG(IS_WIN)
- #include "base/win/windows_version.h"
- #endif
- #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
- #if BUILDFLAG(IS_ANDROID)
- #include "base/android/apk_assets.h"
- #elif BUILDFLAG(IS_MAC)
- #include "base/mac/foundation_util.h"
- #endif
- #endif // V8_USE_EXTERNAL_STARTUP_DATA
- namespace gin {
- namespace {
- // This global is never freed nor closed.
- base::MemoryMappedFile* g_mapped_snapshot = nullptr;
- #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
- absl::optional<gin::V8SnapshotFileType> g_snapshot_file_type;
- #endif
- bool GenerateEntropy(unsigned char* buffer, size_t amount) {
- base::RandBytes(buffer, amount);
- return true;
- }
- void GetMappedFileData(base::MemoryMappedFile* mapped_file,
- v8::StartupData* data) {
- if (mapped_file) {
- data->data = reinterpret_cast<const char*>(mapped_file->data());
- data->raw_size = static_cast<int>(mapped_file->length());
- } else {
- data->data = nullptr;
- data->raw_size = 0;
- }
- }
- #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
- #if BUILDFLAG(IS_ANDROID)
- const char kV8ContextSnapshotFileName64[] = "v8_context_snapshot_64.bin";
- const char kV8ContextSnapshotFileName32[] = "v8_context_snapshot_32.bin";
- const char kSnapshotFileName64[] = "snapshot_blob_64.bin";
- const char kSnapshotFileName32[] = "snapshot_blob_32.bin";
- #if defined(__LP64__)
- #define kV8ContextSnapshotFileName kV8ContextSnapshotFileName64
- #define kSnapshotFileName kSnapshotFileName64
- #else
- #define kV8ContextSnapshotFileName kV8ContextSnapshotFileName32
- #define kSnapshotFileName kSnapshotFileName32
- #endif
- #else // BUILDFLAG(IS_ANDROID)
- #if defined(USE_V8_CONTEXT_SNAPSHOT)
- const char kV8ContextSnapshotFileName[] = V8_CONTEXT_SNAPSHOT_FILENAME;
- #endif
- const char kSnapshotFileName[] = "snapshot_blob.bin";
- #endif // BUILDFLAG(IS_ANDROID)
- const char* GetSnapshotFileName(const V8SnapshotFileType file_type) {
- switch (file_type) {
- case V8SnapshotFileType::kDefault:
- return kSnapshotFileName;
- case V8SnapshotFileType::kWithAdditionalContext:
- #if defined(USE_V8_CONTEXT_SNAPSHOT)
- return kV8ContextSnapshotFileName;
- #else
- NOTREACHED();
- return nullptr;
- #endif
- }
- NOTREACHED();
- return nullptr;
- }
- void GetV8FilePath(const char* file_name, base::FilePath* path_out) {
- #if BUILDFLAG(IS_ANDROID)
- // This is the path within the .apk.
- *path_out =
- base::FilePath(FILE_PATH_LITERAL("assets")).AppendASCII(file_name);
- #elif BUILDFLAG(IS_MAC)
- base::ScopedCFTypeRef<CFStringRef> bundle_resource(
- base::SysUTF8ToCFStringRef(file_name));
- *path_out = base::mac::PathForFrameworkBundleResource(bundle_resource);
- #else
- base::FilePath data_path;
- bool r = base::PathService::Get(base::DIR_ASSETS, &data_path);
- DCHECK(r);
- *path_out = data_path.AppendASCII(file_name);
- #endif
- }
- bool MapV8File(base::File file,
- base::MemoryMappedFile::Region region,
- base::MemoryMappedFile** mmapped_file_out) {
- DCHECK(*mmapped_file_out == NULL);
- std::unique_ptr<base::MemoryMappedFile> mmapped_file(
- new base::MemoryMappedFile());
- if (mmapped_file->Initialize(std::move(file), region)) {
- *mmapped_file_out = mmapped_file.release();
- return true;
- }
- return false;
- }
- base::File OpenV8File(const char* file_name,
- base::MemoryMappedFile::Region* region_out) {
- // Re-try logic here is motivated by http://crbug.com/479537
- // for A/V on Windows (https://support.microsoft.com/en-us/kb/316609).
- // These match tools/metrics/histograms.xml
- enum OpenV8FileResult {
- OPENED = 0,
- OPENED_RETRY,
- FAILED_IN_USE,
- FAILED_OTHER,
- MAX_VALUE
- };
- base::FilePath path;
- GetV8FilePath(file_name, &path);
- #if BUILDFLAG(IS_ANDROID)
- base::File file(base::android::OpenApkAsset(path.value(), region_out));
- OpenV8FileResult result = file.IsValid() ? OpenV8FileResult::OPENED
- : OpenV8FileResult::FAILED_OTHER;
- #else
- // Re-try logic here is motivated by http://crbug.com/479537
- // for A/V on Windows (https://support.microsoft.com/en-us/kb/316609).
- const int kMaxOpenAttempts = 5;
- const int kOpenRetryDelayMillis = 250;
- OpenV8FileResult result = OpenV8FileResult::FAILED_IN_USE;
- int flags = base::File::FLAG_OPEN | base::File::FLAG_READ;
- base::File file;
- for (int attempt = 0; attempt < kMaxOpenAttempts; attempt++) {
- file.Initialize(path, flags);
- if (file.IsValid()) {
- *region_out = base::MemoryMappedFile::Region::kWholeFile;
- if (attempt == 0) {
- result = OpenV8FileResult::OPENED;
- break;
- } else {
- result = OpenV8FileResult::OPENED_RETRY;
- break;
- }
- } else if (file.error_details() != base::File::FILE_ERROR_IN_USE) {
- result = OpenV8FileResult::FAILED_OTHER;
- break;
- } else if (kMaxOpenAttempts - 1 != attempt) {
- base::PlatformThread::Sleep(base::Milliseconds(kOpenRetryDelayMillis));
- }
- }
- #endif // BUILDFLAG(IS_ANDROID)
- UMA_HISTOGRAM_ENUMERATION("V8.Initializer.OpenV8File.Result", result,
- OpenV8FileResult::MAX_VALUE);
- return file;
- }
- #endif // defined(V8_USE_EXTERNAL_STARTUP_DATA)
- template <int LENGTH>
- void SetV8Flags(const char (&flag)[LENGTH]) {
- v8::V8::SetFlagsFromString(flag, LENGTH - 1);
- }
- void SetV8FlagsFormatted(const char* format, ...) {
- char buffer[128];
- va_list args;
- va_start(args, format);
- int length = base::vsnprintf(buffer, sizeof(buffer), format, args);
- if (length <= 0 || sizeof(buffer) <= static_cast<unsigned>(length)) {
- PLOG(ERROR) << "Invalid formatted V8 flag: " << format;
- return;
- }
- v8::V8::SetFlagsFromString(buffer, length);
- }
- template <size_t N, size_t M>
- void SetV8FlagsIfOverridden(const base::Feature& feature,
- const char (&enabling_flag)[N],
- const char (&disabling_flag)[M]) {
- auto overridden_state = base::FeatureList::GetStateIfOverridden(feature);
- if (!overridden_state.has_value()) {
- return;
- }
- if (overridden_state.value()) {
- SetV8Flags(enabling_flag);
- } else {
- SetV8Flags(disabling_flag);
- }
- }
- void SetFlags(IsolateHolder::ScriptMode mode,
- const std::string js_command_line_flags) {
- // We assume that all feature flag defaults correspond to the default
- // values of the corresponding V8 flags.
- SetV8FlagsIfOverridden(features::kV8CompactCodeSpaceWithStack,
- "--compact-code-space-with-stack",
- "--no-compact-code-space-with-stack");
- SetV8FlagsIfOverridden(features::kV8CompactWithStack, "--compact-with-stack",
- "--no-compact-with-stack");
- SetV8FlagsIfOverridden(features::kV8CompactMaps, "--compact-maps",
- "--no-compact-maps");
- SetV8FlagsIfOverridden(features::kV8UseMapSpace, "--use-map-space",
- "--no-use-map-space");
- SetV8FlagsIfOverridden(features::kV8CrashOnEvacuationFailure,
- "--crash-on-aborted-evacuation",
- "--no-crash-on-aborted-evacuation");
- SetV8FlagsIfOverridden(features::kV8OptimizeJavascript, "--opt", "--no-opt");
- SetV8FlagsIfOverridden(features::kV8FlushBytecode, "--flush-bytecode",
- "--no-flush-bytecode");
- SetV8FlagsIfOverridden(features::kV8FlushBaselineCode,
- "--flush-baseline-code", "--no-flush-baseline-code");
- SetV8FlagsIfOverridden(features::kV8OffThreadFinalization,
- "--finalize-streaming-on-background",
- "--no-finalize-streaming-on-background");
- if (base::FeatureList::IsEnabled(features::kV8DelayMemoryReducer)) {
- SetV8FlagsFormatted(
- "--gc-memory-reducer-start-delay-ms=%i",
- static_cast<int>(
- features::kV8MemoryReducerStartDelay.Get().InMilliseconds()));
- }
- SetV8FlagsIfOverridden(features::kV8LazyFeedbackAllocation,
- "--lazy-feedback-allocation",
- "--no-lazy-feedback-allocation");
- SetV8FlagsIfOverridden(features::kV8PerContextMarkingWorklist,
- "--stress-per-context-marking-worklist",
- "--no-stress-per-context-marking-worklist");
- SetV8FlagsIfOverridden(features::kV8FlushEmbeddedBlobICache,
- "--experimental-flush-embedded-blob-icache",
- "--no-experimental-flush-embedded-blob-icache");
- SetV8FlagsIfOverridden(features::kV8ReduceConcurrentMarkingTasks,
- "--gc-experiment-reduce-concurrent-marking-tasks",
- "--no-gc-experiment-reduce-concurrent-marking-tasks");
- SetV8FlagsIfOverridden(features::kV8NoReclaimUnmodifiedWrappers,
- "--no-reclaim-unmodified-wrappers",
- "--reclaim-unmodified-wrappers");
- SetV8FlagsIfOverridden(
- features::kV8ExperimentalRegexpEngine,
- "--enable-experimental-regexp-engine-on-excessive-backtracks",
- "--no-enable-experimental-regexp-engine-on-excessive-backtracks");
- SetV8FlagsIfOverridden(features::kV8TurboFastApiCalls,
- "--turbo-fast-api-calls", "--no-turbo-fast-api-calls");
- SetV8FlagsIfOverridden(features::kV8Turboprop, "--turboprop",
- "--no-turboprop");
- SetV8FlagsIfOverridden(features::kV8Sparkplug, "--sparkplug",
- "--no-sparkplug");
- SetV8FlagsIfOverridden(features::kV8ConcurrentSparkplug,
- "--concurrent-sparkplug", "--no-concurrent-sparkplug");
- SetV8FlagsIfOverridden(features::kV8SparkplugNeedsShortBuiltinCalls,
- "--sparkplug-needs-short-builtins",
- "--no-sparkplug-needs-short-builtins");
- SetV8FlagsIfOverridden(features::kV8ShortBuiltinCalls,
- "--short-builtin-calls", "--no-short-builtin-calls");
- SetV8FlagsIfOverridden(features::kV8CodeMemoryWriteProtection,
- "--write-protect-code-memory",
- "--no-write-protect-code-memory");
- SetV8FlagsIfOverridden(features::kV8SlowHistograms, "--slow-histograms",
- "--no-slow-histograms");
- if (base::FeatureList::IsEnabled(features::kV8ConcurrentSparkplug)) {
- if (int max_threads = features::kV8ConcurrentSparkplugMaxThreads.Get()) {
- SetV8FlagsFormatted("--concurrent-sparkplug-max-threads=%i", max_threads);
- }
- SetV8FlagsIfOverridden(features::kV8ConcurrentSparkplugHighPriorityThreads,
- "--concurrent-sparkplug-high-priority-threads",
- "--no-concurrent-sparkplug-high-priority-threads");
- }
- if (base::FeatureList::IsEnabled(features::kV8FlushBytecode)) {
- if (int old_age = features::kV8FlushBytecodeOldAge.Get()) {
- SetV8FlagsFormatted("--bytecode-old-age=%i", old_age);
- }
- }
- if (base::FeatureList::IsEnabled(features::kV8ScriptAblation)) {
- if (int delay = features::kV8ScriptDelayMs.Get()) {
- SetV8FlagsFormatted("--script-delay=%i", delay);
- }
- if (int delay = features::kV8ScriptDelayOnceMs.Get()) {
- SetV8FlagsFormatted("--script-delay-once=%i", delay);
- }
- if (double fraction = features::kV8ScriptDelayFraction.Get()) {
- SetV8FlagsFormatted("--script-delay-fraction=%f", fraction);
- }
- }
- // Make sure aliases of kV8SlowHistograms only enable the feature to
- // avoid contradicting settings between multiple finch experiments.
- bool any_slow_histograms_alias =
- base::FeatureList::IsEnabled(
- features::kV8SlowHistogramsCodeMemoryWriteProtection) ||
- base::FeatureList::IsEnabled(features::kV8SlowHistogramsSparkplug) ||
- base::FeatureList::IsEnabled(
- features::kV8SlowHistogramsSparkplugAndroid) ||
- base::FeatureList::IsEnabled(features::kV8SlowHistogramsScriptAblation);
- if (any_slow_histograms_alias) {
- SetV8Flags("--slow-histograms");
- } else {
- SetV8FlagsIfOverridden(features::kV8SlowHistograms, "--slow-histograms",
- "--no-slow-histograms");
- }
- if (IsolateHolder::kStrictMode == mode) {
- SetV8Flags("--use_strict");
- }
- if (js_command_line_flags.empty())
- return;
- // Allow the --js-flags switch to override existing flags:
- std::vector<base::StringPiece> flag_list =
- base::SplitStringPiece(js_command_line_flags, ",", base::TRIM_WHITESPACE,
- base::SPLIT_WANT_NONEMPTY);
- for (const auto& flag : flag_list) {
- v8::V8::SetFlagsFromString(std::string(flag).c_str(), flag.size());
- }
- }
- } // namespace
- // static
- void V8Initializer::Initialize(IsolateHolder::ScriptMode mode,
- const std::string js_command_line_flags,
- v8::OOMErrorCallback oom_error_callback) {
- static bool v8_is_initialized = false;
- if (v8_is_initialized)
- return;
- // Flags need to be set before InitializePlatform as they are used for
- // system instrumentation initialization.
- // See https://crbug.com/v8/11043
- SetFlags(mode, js_command_line_flags);
- v8::V8::InitializePlatform(V8Platform::Get());
- // Set this as early as possible in order to ensure OOM errors are reported
- // correctly.
- v8::V8::SetFatalMemoryErrorCallback(oom_error_callback);
- // Set this early on as some initialization steps, such as the initialization
- // of the virtual memory cage, already use V8's random number generator.
- v8::V8::SetEntropySource(&GenerateEntropy);
- #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
- if (g_mapped_snapshot) {
- v8::StartupData snapshot;
- GetMappedFileData(g_mapped_snapshot, &snapshot);
- v8::V8::SetSnapshotDataBlob(&snapshot);
- }
- #endif // V8_USE_EXTERNAL_STARTUP_DATA
- v8::V8::Initialize();
- v8_is_initialized = true;
- #if defined(V8_ENABLE_SANDBOX)
- // Record some sandbox statistics into UMA.
- // The main reason for capturing these histograms here instead of having V8
- // do it is that there are no Isolates available yet, which are required
- // for recording histograms in V8.
- // Record the mode of the sandbox.
- // These values are persisted to logs. Entries should not be renumbered and
- // numeric values should never be reused. This should match enum
- // V8SandboxMode in tools/metrics/histograms/enums.xml.
- enum class V8SandboxMode {
- kSecure = 0,
- kInsecure = 1,
- kMaxValue = kInsecure,
- };
- base::UmaHistogramEnumeration("V8.SandboxMode",
- v8::V8::IsSandboxConfiguredSecurely()
- ? V8SandboxMode::kSecure
- : V8SandboxMode::kInsecure);
- // Record the size of the address space reservation backing the sandbox.
- // The size will always be one of a handful of values, so use a sparse
- // histogram to capture it.
- size_t size = v8::V8::GetSandboxReservationSizeInBytes();
- DCHECK_GT(size, 0U);
- size_t sizeInGB = size >> 30;
- DCHECK_EQ(sizeInGB << 30, size);
- base::UmaHistogramSparse("V8.SandboxReservationSizeGB", sizeInGB);
- // When the sandbox is enabled, ArrayBuffers must be allocated inside of
- // it. To achieve that, PA's ConfigurablePool is created inside the sandbox
- // and Blink then creates the ArrayBuffer partition in that Pool.
- v8::VirtualAddressSpace* sandbox_address_space =
- v8::V8::GetSandboxAddressSpace();
- const size_t max_pool_size = partition_alloc::internal::
- PartitionAddressSpace::ConfigurablePoolMaxSize();
- const size_t min_pool_size = partition_alloc::internal::
- PartitionAddressSpace::ConfigurablePoolMinSize();
- size_t pool_size = max_pool_size;
- #if BUILDFLAG(IS_WIN)
- // On Windows prior to 8.1 we allocate a smaller Pool since reserving
- // virtual memory is expensive on these OSes.
- if (base::win::GetVersion() < base::win::Version::WIN8_1) {
- // The size chosen here should be synchronized with the size of the
- // virtual memory reservation for the V8 sandbox on these platforms.
- // Currently, that is 8GB, of which 4GB are used for V8's pointer
- // compression region.
- // TODO(saelo) give this constant a proper name and maybe move it
- // somewhere else.
- constexpr size_t kGB = 1ULL << 30;
- pool_size = 4ULL * kGB;
- DCHECK_LE(pool_size, max_pool_size);
- DCHECK_GE(pool_size, min_pool_size);
- }
- #endif
- // Try to reserve the maximum size of the pool at first, then keep halving
- // the size on failure until it succeeds.
- uintptr_t pool_base = 0;
- while (!pool_base && pool_size >= min_pool_size) {
- pool_base = sandbox_address_space->AllocatePages(
- 0, pool_size, pool_size, v8::PagePermissions::kNoAccess);
- if (!pool_base) {
- pool_size /= 2;
- }
- }
- // The V8 sandbox is guaranteed to be large enough to host the pool.
- CHECK(pool_base);
- partition_alloc::internal::PartitionAddressSpace::InitConfigurablePool(
- pool_base, pool_size);
- // TODO(saelo) maybe record the size of the Pool into UMA.
- #endif // V8_ENABLE_SANDBOX
- // Initialize the partition used by gin::ArrayBufferAllocator instances. This
- // needs to happen now, after the V8 sandbox has been initialized, so that
- // the partition is placed inside the configurable pool initialized above.
- ArrayBufferAllocator::InitializePartition();
- }
- // static
- void V8Initializer::GetV8ExternalSnapshotData(v8::StartupData* snapshot) {
- GetMappedFileData(g_mapped_snapshot, snapshot);
- }
- // static
- void V8Initializer::GetV8ExternalSnapshotData(const char** snapshot_data_out,
- int* snapshot_size_out) {
- v8::StartupData snapshot;
- GetV8ExternalSnapshotData(&snapshot);
- *snapshot_data_out = snapshot.data;
- *snapshot_size_out = snapshot.raw_size;
- }
- #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
- // static
- void V8Initializer::LoadV8Snapshot(V8SnapshotFileType snapshot_file_type) {
- if (g_mapped_snapshot) {
- // TODO(crbug.com/802962): Confirm not loading different type of snapshot
- // files in a process.
- return;
- }
- base::MemoryMappedFile::Region file_region;
- base::File file =
- OpenV8File(GetSnapshotFileName(snapshot_file_type), &file_region);
- LoadV8SnapshotFromFile(std::move(file), &file_region, snapshot_file_type);
- }
- // static
- void V8Initializer::LoadV8SnapshotFromFile(
- base::File snapshot_file,
- base::MemoryMappedFile::Region* snapshot_file_region,
- V8SnapshotFileType snapshot_file_type) {
- if (g_mapped_snapshot)
- return;
- if (!snapshot_file.IsValid()) {
- LOG(FATAL) << "Error loading V8 startup snapshot file";
- return;
- }
- g_snapshot_file_type = snapshot_file_type;
- base::MemoryMappedFile::Region region =
- base::MemoryMappedFile::Region::kWholeFile;
- if (snapshot_file_region) {
- region = *snapshot_file_region;
- }
- if (!MapV8File(std::move(snapshot_file), region, &g_mapped_snapshot)) {
- LOG(FATAL) << "Error mapping V8 startup snapshot file";
- return;
- }
- }
- #if BUILDFLAG(IS_ANDROID)
- // static
- base::FilePath V8Initializer::GetSnapshotFilePath(
- bool abi_32_bit,
- V8SnapshotFileType snapshot_file_type) {
- base::FilePath path;
- const char* filename = nullptr;
- switch (snapshot_file_type) {
- case V8SnapshotFileType::kDefault:
- filename = abi_32_bit ? kSnapshotFileName32 : kSnapshotFileName64;
- break;
- case V8SnapshotFileType::kWithAdditionalContext:
- filename = abi_32_bit ? kV8ContextSnapshotFileName32
- : kV8ContextSnapshotFileName64;
- break;
- }
- CHECK(filename);
- GetV8FilePath(filename, &path);
- return path;
- }
- #endif // BUILDFLAG(IS_ANDROID)
- V8SnapshotFileType GetLoadedSnapshotFileType() {
- DCHECK(g_snapshot_file_type.has_value());
- return *g_snapshot_file_type;
- }
- #endif // defined(V8_USE_EXTERNAL_STARTUP_DATA)
- } // namespace gin
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