ART Runtime 創建(二)--啟動參數

Android 7.0 aosp_shamu-userdebug

一. 啟動時獲取的參數

AndroidRuntime::startVm(/framework/bae/cpre/jni/AndroidRuntime.cpp)方法會首先獲取大量系統屬性,并將這些系統屬性轉化為實際的啟動參數,下面是獲取的系統屬性以及對應的啟動參數:

  • dalvik.vm.checkjni(ro.kernel.android.checkjni)

真實值:無
默認為false, 如果為true, 則添加參數-Xcheck:jni

  • dalvik.vm.execution-mode

真實值:無
默認為KEMDefault, 有四個取值:KEMDefault, kEMIntPortable, kEMIntFast, kEMJitCompiler. 如果不是kEMDefault,則相應的參數為:-Xint:portable, -Xint:fast, -Xint:jit

  • dalvik.vm.stack-trace-file

真實值:/data/anr/traces.txt
參數的形式為:-Xstacktracefile:/data/anr/traces.txt

  • dalvik.vm.jniopts

真實值:沒有設置
如果有設置的話,參數形式為:Xjnipots:...

  • {exit, runtime_exit}

Hook Runtime的exit()runtime_exit(int code)函數

  • {vfprintf, runtime_vfprintf}

Hook Runtime的fprintf()runtime_vfprintf(FILE* fp, const char* format, va_list ap)函數

  • {sensitiveThread, runtime_isSensitiveThread()}

Hook Runtime的sensitiveThread()runtime_isSensitiveThread()函數

  • 直接添加參數-verbose:gc
  • dalvik.vm.heapstartsize

真實值:8m
參數的形式為:-Xms8m

  • dalvik.vm.heapsize

真實值:512m
參數的形式為:-Xmx512m

  • dalvik.vm.heapgrowthlimit

真實值:256m
參數形式為:-XX:HeapGrowthLimit=256m

  • dalvik.vm.heapminfree

真實值:512k,
參數形式為:-XX:HeapMinFree=512k

  • dalvik.vm.heapmaxfree

真實值:8m
參數形式為:-XX:HeapMaxFree=8m

  • dalvik.vm.heaputilization

真實值:0.75
參數形式為:-XX:HeapTargetUtilization=0.75

  • dalvik.vm.usejit

真實值:true
參數形式為:-Xusejit:true

  • dalvik.vm.jitmaxsize

真實值是:無
如果設置則參數形式為:-Xjitmaxsize:${dalvik.vm.jitmaxsize}

  • dalvik.vm.jitinitialize

真實值:無,
如果設置參數形式為:-Xjitinitialize:${dalvik.vm.jitinitialize}

  • dalvik.vm.jitthreshold

真實值:無
如果設置參數形式為:-Xjitthreshold:..

  • dalvik.vm.usejitprofiles

真實值:true,
參數形式為:-Xjitsaveprofilinginfo

  • dalvik.vm.jitprithreadweight

真實值:無
如果設置,參數的形式為:-Xjitprithreadweight

  • dalvik.vm.jittransitionweight

真實值:無
如果設置,參數的形式為:-Xjittransitionweight:${dalvik.vm.jittransitionweight}

  • ro.config.low_ram

真實值:無
如果設置,參數形式為:-XXLowMemoryMode

  • dalvik.vm.gctype

真實值:無
如果設置,參數形式為:-Xgc:${dalvik.vm.gctype}

  • dalvik.vm.backgroundgctype

真實值:無
如果設置,參數形式為:-XX:BackgroundGC=${dalvik.vm.backgroundgctype}

  • 直接添加參數-agentlib:jdwp=transport=dt_android_adb,suspend=n,server=y
  • dalvik.vm.lockprof.threshold

真實值:500
參數形式為:-Xlockprofthreshold:500

  • vold.decrypt

trigger_restart_framework
因為不等于trigfer_restart_min_framework1,所以還要獲取屬性dalvik.vm.image-dex2oat-filter, 系統中并未設置該值,如果設置了,參數的形式為:--compiler-filter=${dalvik.vm.image-dex2oat-filter}, -Ximage-compiler-option

  • 直接添加參數Ximage-compiler-option

  • 直接添加參數--compiled-classes=/system/etc/preloaded-classes

  • 如果文件/system/etc/compiled-classes存在(實際存在),則添加參數:-Ximage-compiler-option, --compiled-classes=/system/etc/compiled-classes

  • dalvik.vm.imgae-dex2oat-flags

真實值:無
如果設置,參數形式為:-Ximage-compile-option, ${image-dex2oat-flags}

  • dalvik.vm.dex2oat-Xms

真實值:64m
參數形式為:-Xcompiler-option, --runtime-arg, -Xcompiler-option, -Xms64m

  • dalvik.vm.dex2oat-Xmx

真實值:512m
參數形式為:-Xcompiler-option, --runtime-arg, -Xcompiler-option, -Xms512m

  • dalvik.vm.dex2oat-filter

真實值:無
如果設置了,參數的形式為:-Xcompiler-option, --runtime-arg, -Xcompiler-option, --compiler-filter=${dalvik.vm.dex2oat-filter}

  • dalvik.vm.dex2oat-threads

真實值:無
如果設置了,參數形式為:-Xcompiler-option, --runtime-arg, -Xcompiler-option, -j${dalvik.vm.dex2oat-threads}

  • dalvik.vm.image-dex2oat-threads

真實值:無
如果設置了,參數形式為:-Ximage-compiler-option, --runtime-arg, -Ximage-compiler-option, -j${dalvik.vm.image-dex2oat-threads}

  • dalvik.vm.isa.arm.variant

真實值:krait
參數最終形式為:-Ximage-compiler-option, --runtime-arg, -Ximage-compiler-option, --instruction-set-variant=krait , -Xcompiler-option, --runtime-arg, -Xcompiler-option, --instruction-set-variant=krait

  • dalvik.vm.isa.arm.features

真實值:default
參數形式為:-Ximage-compiler-option, --runtime-arg, -Ximage-compiler-option, --instruction-set-features=default, -Xcompiler-option, --runtime-arg, -Xcompiler-option, instruction-set-variant-features=default

  • dalvik.vm.dex2oat-flags

真實值:無
如果設置,參數形式為:-Xcompiler-option, [dex2oat-flags]

  • dalvik.vm.extra-opts

真實值:無
如果設置,參數形式為:[extra-opts]

  • 讀取Locale,然后添加參數-Duser.locale=zh-Hans-CN
  • ro.debuggable

真實值:1,
如果ro.debuggable=1同時dalvik.vm.method-trace=true(實際為false),則添加參數-Xmethod-trace, -Xmethod-trace-file:[dalvik.vm.method-trace-file], -Xmethod-trace-file-size:[dalvik.vm.method-trace-file-siz], 如果dalvik.vm.method-trace-stream=true, 添加參數-Xmethod-trace-stream(實際都沒有添加)

  • ro.dalvik.vm.native.bridge

真實值:0
如果值不為0, 則參數為:-XX:NativeBridge=[ro.dalvik.vm.native.bridge]

  • ro.product.cpu.abilist32

真實值:[armeabi-v7a,armeabi]
參數形式為:--cpu-abilist=[armeabi-v7a,armeabi]

  • dalvik.vm.zygote.max-boot-retry

真實值:無
如果設置, 最終形式為:-Xzygote-max-boot-retry=[dalvik.vm.zygote.max-boot-retry]

  • debug.generate-debug-info

真實值:無
如果值為true, 添加參數:-Xcompiler-option, --generate-debug-info, -Ximage-compiler-option, --generate-debug-info

  • ro.build.fingerprint

真實值:Android/aosp_shamu/shamu:7.0/NBD91U/xx12231922:userdebug/test-keys
參數形式為:-Xfingerprint:Android/aosp_shamu/shamu:7.0/NBD91U/xx12231922:userdebug/test-keys

二. 實際傳入的參數

{
  {`-Xstacktracefile:/data/anr/traces.txt`, NULL}, //{optionString, extraInfo}
  {`exit`, runtime_exit},
  {`vfprintf`, `runtime_vfprintf`},
  {`sensitiveThread`, `runtime_isSensitiveThread`},
  {`-verbose:gc`, NULL},
  {`-Xms8m`, NULL},
  {`-Xmx512m`, NULL},
  {`-XX:HeapGrowthLimit=256m`,NULL},
  {`-XX:HeapMinFree=512k`, NULL},
  {`-XX:HeapMaxFree=8m`,NULL},
  {`-XX:HeapTargetUtilization=0.75`,NULL},
  {`-Xusejit:true`, NULL},
  {`-Xjitsaveprofilinginfo`,NULL},
  {`-agentlib:jdwp=transport=dt_android_adb,suspend=n,server=y`, NULL},
  {`-Xlockprofthreshold:500`,NULL},
  {`-Ximage-compiler-option`,NULL},
  {`--compiled-classes=/system/etc/preloaded-classes`,NULL},
  {`-Ximage-compiler-option`,NULL},
  {`--compiled-classes=/system/etc/compiled-classes`,NULL},
  {`-Xcompiler-option`,NULL},
  {`--runtime-arg`,NULL},
  {`-Xcompiler-option`,NULL},
  {`-Xms64m`,NULL},
  {`-Xcompiler-option`,NULL},
  {`--runtime-arg`,NULL},
  {`-Xcompiler-option`,NULL},
  {`-Xmx512m`,NULL},
  {`-Ximage-compiler-option`,NULL},
  {`--runtime-arg`,NULL},
  {`-Ximage-compiler-option`,NULL},
  {`--instruction-set-variant=krait`,NULL},
  {`-Xcompiler-option`,NULL},
  {`--runtime-arg`,NULL},
  {`-Xcompiler-option`,NULL},
  {`--instruction-set-variant=krait`,NULL},
  {`-Ximage-compiler-option`,NULL},
  {`--runtime-arg`,NULL},
  {`-Ximage-compiler-option`,NULL},
  {`--instruction-set-features=default`,NULL},
  {`-Xcompiler-option`,NULL},
  {`--runtime-arg`,NULL},
  {`-Xcompiler-option`,NULL},
  {`--instruction-set-features=default`,NULL},
  {`-Duser.locale=zh-Hans-CN`,NULL},
  {`--cpu-abilist=[armeabi-v7a,armeabi]`,NULL},
  {`-Xfingerprint:Android/aosp_shamu/shamu:7.0/NBD91U/xx12231922:userdebug/test-keys`, NULL}
}

三. 存儲參數的數據結構和方法

3.1 存儲參數的數據結構

typedef struct JavaVMInitArgs {
  jint          version;
  jint          nOptions;
  JavaVMOption* options;
  jboolean      ignoreUnrecognized
}

typedef struct JavaVMOption {
  const char* optionString;
  void*       extractInfo;
}

typedef std::vector<std::pair<std::string, const void*>> RuntimeOptions

3.2 最終傳入的數據結構

JavaVMInitArgs initArgs;
initArgs.version = JNI_VERSION_1_4;
initArgs.options = mOptions.editArray();
initArgs.nOptions = mOptions.size();
initArgs.ignoreUnrecognized = JNI_FALSE;

3.3 添加參數的方法

void AndroidRuntime::addOption(const char* optionString, void* extraInfo)
{
    JavaVMOption opt;
    opt.optionString = optionString;
    opt.extraInfo = extraInfo;
    mOptions.add(opt);
}

四. 解析參數流程

4.1 JNI_CreateJavaVM

extern "C" jint JNI_CreateJavaVM(JavaVM** p_vm, JNIEnv** p_env, void* vm_args) {
  const JavaVMInitArgs* args = static_cast<JavaVMInitArgs*>(vm_args);
  ...
  RuntimeOptions options;
  for (int i = 0; i < args->nOptions; ++i) {
      JavaVMOption* option = &args->options[i];
      options.push_back(std::make_pair(std::string(option->optionString), option->extraInfo));
  }
  bool ignore_unrecognized = args->ignoreUnrecognized;
  if (!Runtime::Create(options, ignore_unrecognized)) {
      return JNI_ERR;
  }
  ...
}

4.2 Runtime::Create()

bool Runtime::Create(const RuntimeOptions& raw_options, bool ignore_unrecognized) {
  RuntimeArgumentMap runtime_options;

  return ParseOptions(raw_options, ignore_unrecognized, &runtime_options) &&
      Create(std::move(runtime_options));
}

4.3 Runtime::ParseOptions

bool Runtime::ParseOptions(const RuntimeOptions& raw_options,
                           bool ignore_unrecognized,
                           RuntimeArgumentMap* runtime_options) {
  InitLogging(/* argv */ nullptr);  
  bool parsed = ParsedOptions::Parse(raw_options, ignore_unrecognized, runtime_options);
  if (!parsed) {
    LOG(ERROR) << "Failed to parse options";
    return false;
  }
  return true;
}

4.4 ParsedOptions::Parse

位于/art/runtime/parsed_options.cc

bool ParsedOptions::Parse(const RuntimeOptions& options,
                          bool ignore_unrecognized,
                          RuntimeArgumentMap* runtime_options) {
  CHECK(runtime_options != nullptr);
  ParsedOptions parser;
  return parser.DoParse(options, ignore_unrecognized, runtime_options);
}

4.5 ParsedOptions::DoParse

bool ParsedOptions::DoParse(const RuntimeOptions& options,
                            bool ignore_unrecognized,
                            RuntimeArgumentMap* runtime_options) {
  ...
  //將字符串參數生成對應的M::key結構
  auto parser = MakeParser(ignore_unrecognized);

  std::vector<std::string> argv_list;
  //解析帶有extraOption的參數, [5.2]
  if (!ProcessSpecialOptions(options, nullptr, &argv_list)) {
    return false;
  }

  CmdlineResult parse_result = parser->Parse(argv_list);

  // 處理parse errors
  if (parse_result.IsError()) {
    ...
  }

  using M = RuntimeArgumentMap;
  RuntimeArgumentMap args = parser->ReleaseArgumentsMap();

  if (args.Exists(M::Help)) {
    //-help
    Usage(nullptr);
    return false;
  } else if (args.Exists(M::ShowVersion)) {
    //-showversion
    UsageMessage(stdout, "ART version %s\n", Runtime::GetVersion());
    Exit(0);
  } else if (args.Exists(M::BootClassPath)) {
    //-Xbootclasspath
    LOG(INFO) << "setting boot class path to " << *args.Get(M::BootClassPath);
  }

  //-Xusejit和-Xint不能同時使用
  if (args.GetOrDefault(M::UseJitCompilation) && args.GetOrDefault(M::Interpret)) {
    Usage("-Xusejit:true and -Xint cannot be specified together");
    Exit(0);
  }

  //獲取默認的bootclasspath
  if (getenv("BOOTCLASSPATH") != nullptr) {
    args.SetIfMissing(M::BootClassPath, std::string(getenv("BOOTCLASSPATH")));
  }
  //獲取默認的classpath
  if (getenv("CLASSPATH") != nullptr) {
    args.SetIfMissing(M::ClassPath, std::string(getenv("CLASSPATH")));
  }
  //設置參數-XX:ParallelGCThreads=0u
  //kDefaultEnableParallelGC=false
  args.SetIfMissing(M::ParallelGCThreads, gc::Heap::kDefaultEnableParallelGC ?
      static_cast<unsigned int>(sysconf(_SC_NPROCESSORS_CONF) - 1u) : 0u);

  // -verbose:gc
  {
    LogVerbosity *log_verbosity = args.Get(M::Verbose);
    if (log_verbosity != nullptr) {
      gLogVerbosity = *log_verbosity;
    }
  }
  MaybeOverrideVerbosity();

  // 設置-Xprofile:,由于在啟動時沒有指定這個參數,所以使用默認值:
  Trace::SetDefaultClockSource(args.GetOrDefault(M::ProfileClock));
  //再次檢查extraInfo
  if (!ProcessSpecialOptions(options, &args, nullptr)) {
      return false;
  }

  {

    // 如果沒有設置,background回收器是默認的homogeneous compaction
    // 如果foreground回收器是GSS, 則background也是GSS
    // 如果是low memory模式, 則使用semispace
    gc::CollectorType background_collector_type_;
    gc::CollectorType collector_type_ = (XGcOption{}).collector_type_;  // NOLINT [whitespace/braces] [5]
    //查看是否存在-XX:LowMemoryMode,實際上是沒有的
    bool low_memory_mode_ = args.Exists(M::LowMemoryMode);
    //獲取參數-XX:BackgroundGC,實際上并未指定,所以使用默認值
    background_collector_type_ = args.GetOrDefault(M::BackgroundGc);
    {
      //獲取參數-Xgc,實際上參數中并沒有指定
      ...
    }

    if (background_collector_type_ == gc::kCollectorTypeNone) {
      if (collector_type_ != gc::kCollectorTypeGSS) {
        //如果foreground回收器不是GSS,且當前是low_memory_mode,則使用SS, 否則指定為homogeneous compact
        background_collector_type_ = low_memory_mode_ ?
            gc::kCollectorTypeSS : gc::kCollectorTypeHomogeneousSpaceCompact;
      } else {
        background_collector_type_ = collector_type_;
      }
    }

    args.Set(M::BackgroundGc, BackgroundGcOption { background_collector_type_ });
  }

#if defined(ART_TARGET)
  std::string core_jar("/core.jar");
  std::string core_libart_jar("/core-libart.jar");
#else
  // The host uses hostdex files.
  std::string core_jar("/core-hostdex.jar");
  std::string core_libart_jar("/core-libart-hostdex.jar");
#endif
  //獲取-Xbootclasspath,之前已經通過getenv("BOOTCLASSPATH")設置
  auto boot_class_path_string = args.GetOrDefault(M::BootClassPath);
  //在bootclasspath中查找/core.jar, 如果找到的話,則用/core-libart.jar替換
  size_t core_jar_pos = boot_class_path_string.find(core_jar);
  if (core_jar_pos != std::string::npos) {
    boot_class_path_string.replace(core_jar_pos, core_jar.size(), core_libart_jar);
    args.Set(M::BootClassPath, boot_class_path_string);
  }

  {
    //獲取-Xbootclasspath和-Xbootclasspath-location:
    auto&& boot_class_path = args.GetOrDefault(M::BootClassPath);
    auto&& boot_class_path_locations = args.GetOrDefault(M::BootClassPathLocations);
    //實際并未指定-Xbootclasspath-location
    if (args.Exists(M::BootClassPathLocations)) {
      //如果boot_class_path_locations的path數量不等于boot_class_path中的path路徑,打印Usage并返回
      ...
    }
  }
  //如果沒有指定compilercallbacks回調函數(實際參數中并沒有指定)以及沒有指定-Ximage(實際參數也并未指定)
  //指定image文件路徑是/system/framework/boot.art
  if (!args.Exists(M::CompilerCallbacksPtr) && !args.Exists(M::Image)) {
    std::string image = GetAndroidRoot();
    image += "/framework/boot.art";
    args.Set(M::Image, image);
  }

  //獲取-XX:HeapGrowthLimit(實際參數中為256m),判斷是否小于0或者大于-Xmx(實際為512m)
  //如果小于0或者大于-Xmx,則將-XX:HeapGrowthLimit設為-Xmx的值
  if (args.GetOrDefault(M::HeapGrowthLimit) <= 0u ||
      args.GetOrDefault(M::HeapGrowthLimit) > args.GetOrDefault(M::MemoryMaximumSize)) {
    args.Set(M::HeapGrowthLimit, args.GetOrDefault(M::MemoryMaximumSize));
  }

  //實際參數中并沒有指定-Xexperimental
  if (args.GetOrDefault(M::Experimental) & ExperimentalFlags::kLambdas) {
    ...
  }

  *runtime_options = std::move(args);
  return true;
}

DoParse方法主要做了以下幾件事:

  1. 先將所有的字符串參數名稱集中生成對應的RuntimeArgumentMap::[KEY]結構
  2. 從實際傳入的參數中解析extra_info,extra_info用來hook函數,實際傳入的參數中hook的是下面三個函數:exit,vfprintf,sensitiveThread
  3. 判斷傳入的參數中是否有-help,-showversion,如果存在,則打印對應的幫助信息并返回
  4. 確保-Xusejit-Xint不能共同使用
  5. getenv(BOOTCLASSPATH)并設置-Xbootclasspath
  6. getenv(CLASSPATH)并設置-Xclasspath
  7. 設置-XX:ParallelGCThreads=0u
  8. 根據實際傳入的參數設置LogVerbosity
  9. 獲取Xprofile,由于實際參數中沒有設置,所以使用默認值,并設置Trace::SetDefaultClockSource
  10. 再次檢索extra_info
  11. 根據kuseReadBarrier的值確定foreground GC, 如果kuseReadBarrier=true,foregroundGC=CC,否則foregroundGC=default;查看實際參數中是否指定-Xgc,如果指定了則將參數指定的GC設為background GC(實際參數中并未指定);如果foreground GC是GSS,則background GC也是GSS;如果foreground GC不是GSS,則如果實際參數中指定了-XX:LowMemoryMode(實際參數中并未指定), 即低內存模式下backgroundGC=GSS, 否則backgroundGC=homogeneous Space Compact
  12. 如果bootclasspath中包含/core.jar,則用/core-libart.jar替換
  13. 如果指定了-Xbootclasspath-location,檢查-Xbootclasspath-location鎖指定的path數量是否和-Xbootclasspath中的path數量一樣,不一樣輸出Usage并返回
  14. 由于實際參數中并沒有指定-Ximage:和名為compilercallbacksextra_info,指定Runtime的Image文件是/system/framework/boot.art
  15. 確保-XX:HeapGrowthLimit大于0同時小于-Xmx

4.5.1 ParsedOptions::ProcessSpecialOptions

bool ParsedOptions::ProcessSpecialOptions(const RuntimeOptions& options,
                                          RuntimeArgumentMap* runtime_options,
                                          std::vector<std::string>* out_options) {
  using M = RuntimeArgumentMap;

  for (size_t i = 0; i < options.size(); ++i) {
      const std::string option(options[i].first);
      if (option == "bootclasspath") {
        ... //實際并沒有設置
      } else if (option == "compilercallbacks") {
        ... //實際并沒有設置
      } else if (option == "imageinstructionset") {
        ... //實際并沒有設置
      } else if (option == "sensitiveThread") {
        const void* hook = options[i].second;
        bool (*hook_is_sensitive_thread)() = reinterpret_cast<bool (*)()>(const_cast<void*>(hook));

        if (runtime_options != nullptr) {
          runtime_options->Set(M::HookIsSensitiveThread, hook_is_sensitive_thread);
        }
      } else if (option == "vfprintf") {
        const void* hook = options[i].second;
        if (hook == nullptr) {
          Usage("vfprintf argument was nullptr");
          return false;
        }
        int (*hook_vfprintf)(FILE *, const char*, va_list) =
            reinterpret_cast<int (*)(FILE *, const char*, va_list)>(const_cast<void*>(hook));

        if (runtime_options != nullptr) {
          runtime_options->Set(M::HookVfprintf, hook_vfprintf);
        }
        hook_vfprintf_ = hook_vfprintf;
      } else if (option == "exit") {
        const void* hook = options[i].second;
        if (hook == nullptr) {
          Usage("exit argument was nullptr");
          return false;
        }
        void(*hook_exit)(jint) = reinterpret_cast<void(*)(jint)>(const_cast<void*>(hook));
        if (runtime_options != nullptr) {
          runtime_options->Set(M::HookExit, hook_exit);
        }
        hook_exit_ = hook_exit;
      } else if (option == "abort") {
        ... //實際并沒有設置
      } else {
        ... //實際并沒有設置
      }
  }

  return true;
}
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