1 /*
   2  * Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoaderDataGraph.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/moduleEntry.hpp"
  29 #include "jvmtifiles/jvmtiEnv.hpp"
  30 #include "memory/iterator.hpp"
  31 #include "memory/resourceArea.hpp"
  32 #include "oops/klass.inline.hpp"
  33 #include "oops/objArrayKlass.hpp"
  34 #include "oops/objArrayOop.hpp"
  35 #include "oops/oop.inline.hpp"
  36 #include "oops/oopHandle.inline.hpp"
  37 #include "prims/jvmtiEnvBase.hpp"
  38 #include "prims/jvmtiEventController.inline.hpp"
  39 #include "prims/jvmtiExtensions.hpp"
  40 #include "prims/jvmtiImpl.hpp"
  41 #include "prims/jvmtiManageCapabilities.hpp"
  42 #include "prims/jvmtiTagMap.hpp"
  43 #include "prims/jvmtiThreadState.inline.hpp"
  44 #include "runtime/biasedLocking.hpp"
  45 #include "runtime/deoptimization.hpp"
  46 #include "runtime/frame.inline.hpp"
  47 #include "runtime/handles.inline.hpp"
  48 #include "runtime/interfaceSupport.inline.hpp"
  49 #include "runtime/jfieldIDWorkaround.hpp"
  50 #include "runtime/jniHandles.inline.hpp"
  51 #include "runtime/objectMonitor.inline.hpp"
  52 #include "runtime/osThread.hpp"
  53 #include "runtime/signature.hpp"
  54 #include "runtime/thread.inline.hpp"
  55 #include "runtime/threadSMR.hpp"
  56 #include "runtime/vframe.inline.hpp"
  57 #include "runtime/vframe_hp.hpp"
  58 #include "runtime/vmThread.hpp"
  59 #include "runtime/vmOperations.hpp"
  60 
  61 
  62 ///////////////////////////////////////////////////////////////
  63 //
  64 // JvmtiEnvBase
  65 //
  66 
  67 JvmtiEnvBase* JvmtiEnvBase::_head_environment = NULL;
  68 
  69 bool JvmtiEnvBase::_globally_initialized = false;
  70 volatile bool JvmtiEnvBase::_needs_clean_up = false;
  71 
  72 jvmtiPhase JvmtiEnvBase::_phase = JVMTI_PHASE_PRIMORDIAL;
  73 
  74 volatile int JvmtiEnvBase::_dying_thread_env_iteration_count = 0;
  75 
  76 extern jvmtiInterface_1_ jvmti_Interface;
  77 extern jvmtiInterface_1_ jvmtiTrace_Interface;
  78 
  79 
  80 // perform initializations that must occur before any JVMTI environments
  81 // are released but which should only be initialized once (no matter
  82 // how many environments are created).
  83 void
  84 JvmtiEnvBase::globally_initialize() {
  85   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
  86   assert(_globally_initialized == false, "bad call");
  87 
  88   JvmtiManageCapabilities::initialize();
  89 
  90   // register extension functions and events
  91   JvmtiExtensions::register_extensions();
  92 
  93 #ifdef JVMTI_TRACE
  94   JvmtiTrace::initialize();
  95 #endif
  96 
  97   _globally_initialized = true;
  98 }
  99 
 100 
 101 void
 102 JvmtiEnvBase::initialize() {
 103   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
 104 
 105   // Add this environment to the end of the environment list (order is important)
 106   {
 107     // This block of code must not contain any safepoints, as list deallocation
 108     // (which occurs at a safepoint) cannot occur simultaneously with this list
 109     // addition.  Note: NoSafepointVerifier cannot, currently, be used before
 110     // threads exist.
 111     JvmtiEnvIterator it;
 112     JvmtiEnvBase *previous_env = NULL;
 113     for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
 114       previous_env = env;
 115     }
 116     if (previous_env == NULL) {
 117       _head_environment = this;
 118     } else {
 119       previous_env->set_next_environment(this);
 120     }
 121   }
 122 
 123   if (_globally_initialized == false) {
 124     globally_initialize();
 125   }
 126 }
 127 
 128 jvmtiPhase
 129 JvmtiEnvBase::phase() {
 130   // For the JVMTI environments possessed the can_generate_early_vmstart:
 131   //   replace JVMTI_PHASE_PRIMORDIAL with JVMTI_PHASE_START
 132   if (_phase == JVMTI_PHASE_PRIMORDIAL &&
 133       JvmtiExport::early_vmstart_recorded() &&
 134       early_vmstart_env()) {
 135     return JVMTI_PHASE_START;
 136   }
 137   return _phase; // Normal case
 138 }
 139 
 140 bool
 141 JvmtiEnvBase::is_valid() {
 142   jint value = 0;
 143 
 144   // This object might not be a JvmtiEnvBase so we can't assume
 145   // the _magic field is properly aligned. Get the value in a safe
 146   // way and then check against JVMTI_MAGIC.
 147 
 148   switch (sizeof(_magic)) {
 149   case 2:
 150     value = Bytes::get_native_u2((address)&_magic);
 151     break;
 152 
 153   case 4:
 154     value = Bytes::get_native_u4((address)&_magic);
 155     break;
 156 
 157   case 8:
 158     value = Bytes::get_native_u8((address)&_magic);
 159     break;
 160 
 161   default:
 162     guarantee(false, "_magic field is an unexpected size");
 163   }
 164 
 165   return value == JVMTI_MAGIC;
 166 }
 167 
 168 
 169 bool
 170 JvmtiEnvBase::use_version_1_0_semantics() {
 171   int major, minor, micro;
 172 
 173   JvmtiExport::decode_version_values(_version, &major, &minor, &micro);
 174   return major == 1 && minor == 0;  // micro version doesn't matter here
 175 }
 176 
 177 
 178 bool
 179 JvmtiEnvBase::use_version_1_1_semantics() {
 180   int major, minor, micro;
 181 
 182   JvmtiExport::decode_version_values(_version, &major, &minor, &micro);
 183   return major == 1 && minor == 1;  // micro version doesn't matter here
 184 }
 185 
 186 bool
 187 JvmtiEnvBase::use_version_1_2_semantics() {
 188   int major, minor, micro;
 189 
 190   JvmtiExport::decode_version_values(_version, &major, &minor, &micro);
 191   return major == 1 && minor == 2;  // micro version doesn't matter here
 192 }
 193 
 194 
 195 JvmtiEnvBase::JvmtiEnvBase(jint version) : _env_event_enable() {
 196   _version = version;
 197   _env_local_storage = NULL;
 198   _tag_map = NULL;
 199   _native_method_prefix_count = 0;
 200   _native_method_prefixes = NULL;
 201   _next = NULL;
 202   _class_file_load_hook_ever_enabled = false;
 203 
 204   // Moot since ClassFileLoadHook not yet enabled.
 205   // But "true" will give a more predictable ClassFileLoadHook behavior
 206   // for environment creation during ClassFileLoadHook.
 207   _is_retransformable = true;
 208 
 209   // all callbacks initially NULL
 210   memset(&_event_callbacks,0,sizeof(jvmtiEventCallbacks));
 211 
 212   // all capabilities initially off
 213   memset(&_current_capabilities, 0, sizeof(_current_capabilities));
 214 
 215   // all prohibited capabilities initially off
 216   memset(&_prohibited_capabilities, 0, sizeof(_prohibited_capabilities));
 217 
 218   _magic = JVMTI_MAGIC;
 219 
 220   JvmtiEventController::env_initialize((JvmtiEnv*)this);
 221 
 222 #ifdef JVMTI_TRACE
 223   _jvmti_external.functions = TraceJVMTI != NULL ? &jvmtiTrace_Interface : &jvmti_Interface;
 224 #else
 225   _jvmti_external.functions = &jvmti_Interface;
 226 #endif
 227 }
 228 
 229 
 230 void
 231 JvmtiEnvBase::dispose() {
 232 
 233 #ifdef JVMTI_TRACE
 234   JvmtiTrace::shutdown();
 235 #endif
 236 
 237   // Dispose of event info and let the event controller call us back
 238   // in a locked state (env_dispose, below)
 239   JvmtiEventController::env_dispose(this);
 240 }
 241 
 242 void
 243 JvmtiEnvBase::env_dispose() {
 244   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
 245 
 246   // We have been entered with all events disabled on this environment.
 247   // A race to re-enable events (by setting callbacks) is prevented by
 248   // checking for a valid environment when setting callbacks (while
 249   // holding the JvmtiThreadState_lock).
 250 
 251   // Mark as invalid.
 252   _magic = DISPOSED_MAGIC;
 253 
 254   // Relinquish all capabilities.
 255   jvmtiCapabilities *caps = get_capabilities();
 256   JvmtiManageCapabilities::relinquish_capabilities(caps, caps, caps);
 257 
 258   // Same situation as with events (see above)
 259   set_native_method_prefixes(0, NULL);
 260 
 261   JvmtiTagMap* tag_map_to_clear = tag_map_acquire();
 262   // A tag map can be big, clear it now to save memory until
 263   // the destructor runs.
 264   if (tag_map_to_clear != NULL) {
 265     tag_map_to_clear->clear();
 266   }
 267 
 268   _needs_clean_up = true;
 269 }
 270 
 271 
 272 JvmtiEnvBase::~JvmtiEnvBase() {
 273   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
 274 
 275   // There is a small window of time during which the tag map of a
 276   // disposed environment could have been reallocated.
 277   // Make sure it is gone.
 278   JvmtiTagMap* tag_map_to_deallocate = _tag_map;
 279   set_tag_map(NULL);
 280   // A tag map can be big, deallocate it now
 281   if (tag_map_to_deallocate != NULL) {
 282     delete tag_map_to_deallocate;
 283   }
 284 
 285   _magic = BAD_MAGIC;
 286 }
 287 
 288 
 289 void
 290 JvmtiEnvBase::periodic_clean_up() {
 291   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
 292 
 293   // JvmtiEnvBase reference is saved in JvmtiEnvThreadState. So
 294   // clean up JvmtiThreadState before deleting JvmtiEnv pointer.
 295   JvmtiThreadState::periodic_clean_up();
 296 
 297   // Unlink all invalid environments from the list of environments
 298   // and deallocate them
 299   JvmtiEnvIterator it;
 300   JvmtiEnvBase* previous_env = NULL;
 301   JvmtiEnvBase* env = it.first();
 302   while (env != NULL) {
 303     if (env->is_valid()) {
 304       previous_env = env;
 305       env = it.next(env);
 306     } else {
 307       // This one isn't valid, remove it from the list and deallocate it
 308       JvmtiEnvBase* defunct_env = env;
 309       env = it.next(env);
 310       if (previous_env == NULL) {
 311         _head_environment = env;
 312       } else {
 313         previous_env->set_next_environment(env);
 314       }
 315       delete defunct_env;
 316     }
 317   }
 318 
 319 }
 320 
 321 
 322 void
 323 JvmtiEnvBase::check_for_periodic_clean_up() {
 324   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
 325 
 326   class ThreadInsideIterationClosure: public ThreadClosure {
 327    private:
 328     bool _inside;
 329    public:
 330     ThreadInsideIterationClosure() : _inside(false) {};
 331 
 332     void do_thread(Thread* thread) {
 333       _inside |= thread->is_inside_jvmti_env_iteration();
 334     }
 335 
 336     bool is_inside_jvmti_env_iteration() {
 337       return _inside;
 338     }
 339   };
 340 
 341   if (_needs_clean_up) {
 342     // Check if we are currently iterating environment,
 343     // deallocation should not occur if we are
 344     ThreadInsideIterationClosure tiic;
 345     Threads::threads_do(&tiic);
 346     if (!tiic.is_inside_jvmti_env_iteration() &&
 347              !is_inside_dying_thread_env_iteration()) {
 348       _needs_clean_up = false;
 349       JvmtiEnvBase::periodic_clean_up();
 350     }
 351   }
 352 }
 353 
 354 
 355 void
 356 JvmtiEnvBase::record_first_time_class_file_load_hook_enabled() {
 357   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(),
 358          "sanity check");
 359 
 360   if (!_class_file_load_hook_ever_enabled) {
 361     _class_file_load_hook_ever_enabled = true;
 362 
 363     if (get_capabilities()->can_retransform_classes) {
 364       _is_retransformable = true;
 365     } else {
 366       _is_retransformable = false;
 367 
 368       // cannot add retransform capability after ClassFileLoadHook has been enabled
 369       get_prohibited_capabilities()->can_retransform_classes = 1;
 370     }
 371   }
 372 }
 373 
 374 
 375 void
 376 JvmtiEnvBase::record_class_file_load_hook_enabled() {
 377   if (!_class_file_load_hook_ever_enabled) {
 378     if (Threads::number_of_threads() == 0) {
 379       record_first_time_class_file_load_hook_enabled();
 380     } else {
 381       MutexLocker mu(JvmtiThreadState_lock);
 382       record_first_time_class_file_load_hook_enabled();
 383     }
 384   }
 385 }
 386 
 387 
 388 jvmtiError
 389 JvmtiEnvBase::set_native_method_prefixes(jint prefix_count, char** prefixes) {
 390   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(),
 391          "sanity check");
 392 
 393   int old_prefix_count = get_native_method_prefix_count();
 394   char **old_prefixes = get_native_method_prefixes();
 395 
 396   // allocate and install the new prefixex
 397   if (prefix_count == 0 || !is_valid()) {
 398     _native_method_prefix_count = 0;
 399     _native_method_prefixes = NULL;
 400   } else {
 401     // there are prefixes, allocate an array to hold them, and fill it
 402     char** new_prefixes = (char**)os::malloc((prefix_count) * sizeof(char*), mtInternal);
 403     if (new_prefixes == NULL) {
 404       return JVMTI_ERROR_OUT_OF_MEMORY;
 405     }
 406     for (int i = 0; i < prefix_count; i++) {
 407       char* prefix = prefixes[i];
 408       if (prefix == NULL) {
 409         for (int j = 0; j < (i-1); j++) {
 410           os::free(new_prefixes[j]);
 411         }
 412         os::free(new_prefixes);
 413         return JVMTI_ERROR_NULL_POINTER;
 414       }
 415       prefix = os::strdup(prefixes[i]);
 416       if (prefix == NULL) {
 417         for (int j = 0; j < (i-1); j++) {
 418           os::free(new_prefixes[j]);
 419         }
 420         os::free(new_prefixes);
 421         return JVMTI_ERROR_OUT_OF_MEMORY;
 422       }
 423       new_prefixes[i] = prefix;
 424     }
 425     _native_method_prefix_count = prefix_count;
 426     _native_method_prefixes = new_prefixes;
 427   }
 428 
 429   // now that we know the new prefixes have been successfully installed we can
 430   // safely remove the old ones
 431   if (old_prefix_count != 0) {
 432     for (int i = 0; i < old_prefix_count; i++) {
 433       os::free(old_prefixes[i]);
 434     }
 435     os::free(old_prefixes);
 436   }
 437 
 438   return JVMTI_ERROR_NONE;
 439 }
 440 
 441 
 442 // Collect all the prefixes which have been set in any JVM TI environments
 443 // by the SetNativeMethodPrefix(es) functions.  Be sure to maintain the
 444 // order of environments and the order of prefixes within each environment.
 445 // Return in a resource allocated array.
 446 char**
 447 JvmtiEnvBase::get_all_native_method_prefixes(int* count_ptr) {
 448   assert(Threads::number_of_threads() == 0 ||
 449          SafepointSynchronize::is_at_safepoint() ||
 450          JvmtiThreadState_lock->is_locked(),
 451          "sanity check");
 452 
 453   int total_count = 0;
 454   GrowableArray<char*>* prefix_array =new GrowableArray<char*>(5);
 455 
 456   JvmtiEnvIterator it;
 457   for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
 458     int prefix_count = env->get_native_method_prefix_count();
 459     char** prefixes = env->get_native_method_prefixes();
 460     for (int j = 0; j < prefix_count; j++) {
 461       // retrieve a prefix and so that it is safe against asynchronous changes
 462       // copy it into the resource area
 463       char* prefix = prefixes[j];
 464       char* prefix_copy = NEW_RESOURCE_ARRAY(char, strlen(prefix)+1);
 465       strcpy(prefix_copy, prefix);
 466       prefix_array->at_put_grow(total_count++, prefix_copy);
 467     }
 468   }
 469 
 470   char** all_prefixes = NEW_RESOURCE_ARRAY(char*, total_count);
 471   char** p = all_prefixes;
 472   for (int i = 0; i < total_count; ++i) {
 473     *p++ = prefix_array->at(i);
 474   }
 475   *count_ptr = total_count;
 476   return all_prefixes;
 477 }
 478 
 479 void
 480 JvmtiEnvBase::set_event_callbacks(const jvmtiEventCallbacks* callbacks,
 481                                                jint size_of_callbacks) {
 482   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
 483 
 484   size_t byte_cnt = sizeof(jvmtiEventCallbacks);
 485 
 486   // clear in either case to be sure we got any gap between sizes
 487   memset(&_event_callbacks, 0, byte_cnt);
 488 
 489   // Now that JvmtiThreadState_lock is held, prevent a possible race condition where events
 490   // are re-enabled by a call to set event callbacks where the DisposeEnvironment
 491   // occurs after the boiler-plate environment check and before the lock is acquired.
 492   if (callbacks != NULL && is_valid()) {
 493     if (size_of_callbacks < (jint)byte_cnt) {
 494       byte_cnt = size_of_callbacks;
 495     }
 496     memcpy(&_event_callbacks, callbacks, byte_cnt);
 497   }
 498 }
 499 
 500 
 501 // In the fullness of time, all users of the method should instead
 502 // directly use allocate, besides being cleaner and faster, this will
 503 // mean much better out of memory handling
 504 unsigned char *
 505 JvmtiEnvBase::jvmtiMalloc(jlong size) {
 506   unsigned char* mem = NULL;
 507   jvmtiError result = allocate(size, &mem);
 508   assert(result == JVMTI_ERROR_NONE, "Allocate failed");
 509   return mem;
 510 }
 511 
 512 
 513 // Handle management
 514 
 515 jobject JvmtiEnvBase::jni_reference(Handle hndl) {
 516   return JNIHandles::make_local(hndl());
 517 }
 518 
 519 jobject JvmtiEnvBase::jni_reference(JavaThread *thread, Handle hndl) {
 520   return JNIHandles::make_local(thread, hndl());
 521 }
 522 
 523 void JvmtiEnvBase::destroy_jni_reference(jobject jobj) {
 524   JNIHandles::destroy_local(jobj);
 525 }
 526 
 527 void JvmtiEnvBase::destroy_jni_reference(JavaThread *thread, jobject jobj) {
 528   JNIHandles::destroy_local(jobj); // thread is unused.
 529 }
 530 
 531 //
 532 // Threads
 533 //
 534 
 535 jobject *
 536 JvmtiEnvBase::new_jobjectArray(int length, Handle *handles) {
 537   if (length == 0) {
 538     return NULL;
 539   }
 540 
 541   jobject *objArray = (jobject *) jvmtiMalloc(sizeof(jobject) * length);
 542   NULL_CHECK(objArray, NULL);
 543 
 544   for (int i=0; i<length; i++) {
 545     objArray[i] = jni_reference(handles[i]);
 546   }
 547   return objArray;
 548 }
 549 
 550 jthread *
 551 JvmtiEnvBase::new_jthreadArray(int length, Handle *handles) {
 552   return (jthread *) new_jobjectArray(length,handles);
 553 }
 554 
 555 jthreadGroup *
 556 JvmtiEnvBase::new_jthreadGroupArray(int length, Handle *handles) {
 557   return (jthreadGroup *) new_jobjectArray(length,handles);
 558 }
 559 
 560 // return the vframe on the specified thread and depth, NULL if no such frame
 561 // The thread and the oops in the returned vframe might not have been process.
 562 vframe*
 563 JvmtiEnvBase::vframeForNoProcess(JavaThread* java_thread, jint depth) {
 564   if (!java_thread->has_last_Java_frame()) {
 565     return NULL;
 566   }
 567   RegisterMap reg_map(java_thread, true /* update_map */, false /* process_frames */);
 568   vframe *vf = java_thread->last_java_vframe(&reg_map);
 569   int d = 0;
 570   while ((vf != NULL) && (d < depth)) {
 571     vf = vf->java_sender();
 572     d++;
 573   }
 574   return vf;
 575 }
 576 
 577 
 578 //
 579 // utilities: JNI objects
 580 //
 581 
 582 
 583 jclass
 584 JvmtiEnvBase::get_jni_class_non_null(Klass* k) {
 585   assert(k != NULL, "k != NULL");
 586   Thread *thread = Thread::current();
 587   return (jclass)jni_reference(Handle(thread, k->java_mirror()));
 588 }
 589 
 590 //
 591 // Field Information
 592 //
 593 
 594 bool
 595 JvmtiEnvBase::get_field_descriptor(Klass* k, jfieldID field, fieldDescriptor* fd) {
 596   if (!jfieldIDWorkaround::is_valid_jfieldID(k, field)) {
 597     return false;
 598   }
 599   bool found = false;
 600   if (jfieldIDWorkaround::is_static_jfieldID(field)) {
 601     JNIid* id = jfieldIDWorkaround::from_static_jfieldID(field);
 602     found = id->find_local_field(fd);
 603   } else {
 604     // Non-static field. The fieldID is really the offset of the field within the object.
 605     int offset = jfieldIDWorkaround::from_instance_jfieldID(k, field);
 606     found = InstanceKlass::cast(k)->find_field_from_offset(offset, false, fd);
 607   }
 608   return found;
 609 }
 610 
 611 //
 612 // Object Monitor Information
 613 //
 614 
 615 //
 616 // Count the number of objects for a lightweight monitor. The hobj
 617 // parameter is object that owns the monitor so this routine will
 618 // count the number of times the same object was locked by frames
 619 // in java_thread.
 620 //
 621 jint
 622 JvmtiEnvBase::count_locked_objects(JavaThread *java_thread, Handle hobj) {
 623   jint ret = 0;
 624   if (!java_thread->has_last_Java_frame()) {
 625     return ret;  // no Java frames so no monitors
 626   }
 627 
 628   Thread* current_thread = Thread::current();
 629   ResourceMark rm(current_thread);
 630   HandleMark   hm(current_thread);
 631   RegisterMap  reg_map(java_thread);
 632 
 633   for(javaVFrame *jvf=java_thread->last_java_vframe(&reg_map); jvf != NULL;
 634                                                  jvf = jvf->java_sender()) {
 635     GrowableArray<MonitorInfo*>* mons = jvf->monitors();
 636     if (!mons->is_empty()) {
 637       for (int i = 0; i < mons->length(); i++) {
 638         MonitorInfo *mi = mons->at(i);
 639         if (mi->owner_is_scalar_replaced()) continue;
 640 
 641         // see if owner of the monitor is our object
 642         if (mi->owner() != NULL && mi->owner() == hobj()) {
 643           ret++;
 644         }
 645       }
 646     }
 647   }
 648   return ret;
 649 }
 650 
 651 
 652 
 653 jvmtiError
 654 JvmtiEnvBase::get_current_contended_monitor(JavaThread *calling_thread, JavaThread *java_thread, jobject *monitor_ptr) {
 655   Thread *current_thread = Thread::current();
 656   assert(java_thread->is_handshake_safe_for(current_thread),
 657          "call by myself or at handshake");
 658   oop obj = NULL;
 659   // The ObjectMonitor* can't be async deflated since we are either
 660   // at a safepoint or the calling thread is operating on itself so
 661   // it cannot leave the underlying wait()/enter() call.
 662   ObjectMonitor *mon = java_thread->current_waiting_monitor();
 663   if (mon == NULL) {
 664     // thread is not doing an Object.wait() call
 665     mon = java_thread->current_pending_monitor();
 666     if (mon != NULL) {
 667       // The thread is trying to enter() an ObjectMonitor.
 668       obj = mon->object();
 669       assert(obj != NULL, "ObjectMonitor should have a valid object!");
 670     }
 671     // implied else: no contended ObjectMonitor
 672   } else {
 673     // thread is doing an Object.wait() call
 674     obj = mon->object();
 675     assert(obj != NULL, "Object.wait() should have an object");
 676   }
 677 
 678   if (obj == NULL) {
 679     *monitor_ptr = NULL;
 680   } else {
 681     HandleMark hm(current_thread);
 682     Handle     hobj(current_thread, obj);
 683     *monitor_ptr = jni_reference(calling_thread, hobj);
 684   }
 685   return JVMTI_ERROR_NONE;
 686 }
 687 
 688 
 689 jvmtiError
 690 JvmtiEnvBase::get_owned_monitors(JavaThread *calling_thread, JavaThread* java_thread,
 691                                  GrowableArray<jvmtiMonitorStackDepthInfo*> *owned_monitors_list) {
 692   // Note:
 693   // calling_thread is the thread that requested the list of monitors for java_thread.
 694   // java_thread is the thread owning the monitors.
 695   // current_thread is the thread executing this code, can be a non-JavaThread (e.g. VM Thread).
 696   // And they all may be different threads.
 697   jvmtiError err = JVMTI_ERROR_NONE;
 698   Thread *current_thread = Thread::current();
 699   assert(java_thread->is_handshake_safe_for(current_thread),
 700          "call by myself or at handshake");
 701 
 702   if (java_thread->has_last_Java_frame()) {
 703     ResourceMark rm(current_thread);
 704     HandleMark   hm(current_thread);
 705     RegisterMap  reg_map(java_thread);
 706 
 707     int depth = 0;
 708     for (javaVFrame *jvf = java_thread->last_java_vframe(&reg_map); jvf != NULL;
 709          jvf = jvf->java_sender()) {
 710       if (MaxJavaStackTraceDepth == 0 || depth++ < MaxJavaStackTraceDepth) {  // check for stack too deep
 711         // add locked objects for this frame into list
 712         err = get_locked_objects_in_frame(calling_thread, java_thread, jvf, owned_monitors_list, depth-1);
 713         if (err != JVMTI_ERROR_NONE) {
 714           return err;
 715         }
 716       }
 717     }
 718   }
 719 
 720   // Get off stack monitors. (e.g. acquired via jni MonitorEnter).
 721   JvmtiMonitorClosure jmc(calling_thread, owned_monitors_list, this);
 722   ObjectSynchronizer::monitors_iterate(&jmc, java_thread);
 723   err = jmc.error();
 724 
 725   return err;
 726 }
 727 
 728 // Save JNI local handles for any objects that this frame owns.
 729 jvmtiError
 730 JvmtiEnvBase::get_locked_objects_in_frame(JavaThread* calling_thread, JavaThread* java_thread,
 731                                  javaVFrame *jvf, GrowableArray<jvmtiMonitorStackDepthInfo*>* owned_monitors_list, jint stack_depth) {
 732   jvmtiError err = JVMTI_ERROR_NONE;
 733   Thread* current_thread = Thread::current();
 734   ResourceMark rm(current_thread);
 735   HandleMark   hm(current_thread);
 736 
 737   GrowableArray<MonitorInfo*>* mons = jvf->monitors();
 738   if (mons->is_empty()) {
 739     return err;  // this javaVFrame holds no monitors
 740   }
 741 
 742   oop wait_obj = NULL;
 743   {
 744     // The ObjectMonitor* can't be async deflated since we are either
 745     // at a safepoint or the calling thread is operating on itself so
 746     // it cannot leave the underlying wait() call.
 747     // Save object of current wait() call (if any) for later comparison.
 748     ObjectMonitor *mon = java_thread->current_waiting_monitor();
 749     if (mon != NULL) {
 750       wait_obj = mon->object();
 751     }
 752   }
 753   oop pending_obj = NULL;
 754   {
 755     // The ObjectMonitor* can't be async deflated since we are either
 756     // at a safepoint or the calling thread is operating on itself so
 757     // it cannot leave the underlying enter() call.
 758     // Save object of current enter() call (if any) for later comparison.
 759     ObjectMonitor *mon = java_thread->current_pending_monitor();
 760     if (mon != NULL) {
 761       pending_obj = mon->object();
 762     }
 763   }
 764 
 765   for (int i = 0; i < mons->length(); i++) {
 766     MonitorInfo *mi = mons->at(i);
 767 
 768     if (mi->owner_is_scalar_replaced()) continue;
 769 
 770     oop obj = mi->owner();
 771     if (obj == NULL) {
 772       // this monitor doesn't have an owning object so skip it
 773       continue;
 774     }
 775 
 776     if (wait_obj == obj) {
 777       // the thread is waiting on this monitor so it isn't really owned
 778       continue;
 779     }
 780 
 781     if (pending_obj == obj) {
 782       // the thread is pending on this monitor so it isn't really owned
 783       continue;
 784     }
 785 
 786     if (owned_monitors_list->length() > 0) {
 787       // Our list has at least one object on it so we have to check
 788       // for recursive object locking
 789       bool found = false;
 790       for (int j = 0; j < owned_monitors_list->length(); j++) {
 791         jobject jobj = ((jvmtiMonitorStackDepthInfo*)owned_monitors_list->at(j))->monitor;
 792         oop check = JNIHandles::resolve(jobj);
 793         if (check == obj) {
 794           found = true;  // we found the object
 795           break;
 796         }
 797       }
 798 
 799       if (found) {
 800         // already have this object so don't include it
 801         continue;
 802       }
 803     }
 804 
 805     // add the owning object to our list
 806     jvmtiMonitorStackDepthInfo *jmsdi;
 807     err = allocate(sizeof(jvmtiMonitorStackDepthInfo), (unsigned char **)&jmsdi);
 808     if (err != JVMTI_ERROR_NONE) {
 809         return err;
 810     }
 811     Handle hobj(Thread::current(), obj);
 812     jmsdi->monitor = jni_reference(calling_thread, hobj);
 813     jmsdi->stack_depth = stack_depth;
 814     owned_monitors_list->append(jmsdi);
 815   }
 816 
 817   return err;
 818 }
 819 
 820 jvmtiError
 821 JvmtiEnvBase::get_stack_trace(JavaThread *java_thread,
 822                               jint start_depth, jint max_count,
 823                               jvmtiFrameInfo* frame_buffer, jint* count_ptr) {
 824 #ifdef ASSERT
 825   uint32_t debug_bits = 0;
 826 #endif
 827   Thread *current_thread = Thread::current();
 828   assert(SafepointSynchronize::is_at_safepoint() ||
 829          java_thread->is_handshake_safe_for(current_thread),
 830          "call by myself / at safepoint / at handshake");
 831   int count = 0;
 832   if (java_thread->has_last_Java_frame()) {
 833     RegisterMap reg_map(java_thread, false /* update_map */, false /* process_frames */);
 834     ResourceMark rm(current_thread);
 835     javaVFrame *jvf = java_thread->last_java_vframe(&reg_map);
 836     HandleMark hm(current_thread);
 837     if (start_depth != 0) {
 838       if (start_depth > 0) {
 839         for (int j = 0; j < start_depth && jvf != NULL; j++) {
 840           jvf = jvf->java_sender();
 841         }
 842         if (jvf == NULL) {
 843           // start_depth is deeper than the stack depth
 844           return JVMTI_ERROR_ILLEGAL_ARGUMENT;
 845         }
 846       } else { // start_depth < 0
 847         // we are referencing the starting depth based on the oldest
 848         // part of the stack.
 849         // optimize to limit the number of times that java_sender() is called
 850         javaVFrame *jvf_cursor = jvf;
 851         javaVFrame *jvf_prev = NULL;
 852         javaVFrame *jvf_prev_prev = NULL;
 853         int j = 0;
 854         while (jvf_cursor != NULL) {
 855           jvf_prev_prev = jvf_prev;
 856           jvf_prev = jvf_cursor;
 857           for (j = 0; j > start_depth && jvf_cursor != NULL; j--) {
 858             jvf_cursor = jvf_cursor->java_sender();
 859           }
 860         }
 861         if (j == start_depth) {
 862           // previous pointer is exactly where we want to start
 863           jvf = jvf_prev;
 864         } else {
 865           // we need to back up further to get to the right place
 866           if (jvf_prev_prev == NULL) {
 867             // the -start_depth is greater than the stack depth
 868             return JVMTI_ERROR_ILLEGAL_ARGUMENT;
 869           }
 870           // j now is the number of frames on the stack starting with
 871           // jvf_prev, we start from jvf_prev_prev and move older on
 872           // the stack that many, the result is -start_depth frames
 873           // remaining.
 874           jvf = jvf_prev_prev;
 875           for (; j < 0; j++) {
 876             jvf = jvf->java_sender();
 877           }
 878         }
 879       }
 880     }
 881     for (; count < max_count && jvf != NULL; count++) {
 882       frame_buffer[count].method = jvf->method()->jmethod_id();
 883       frame_buffer[count].location = (jvf->method()->is_native() ? -1 : jvf->bci());
 884       jvf = jvf->java_sender();
 885     }
 886   } else {
 887     if (start_depth != 0) {
 888       // no frames and there is a starting depth
 889       return JVMTI_ERROR_ILLEGAL_ARGUMENT;
 890     }
 891   }
 892   *count_ptr = count;
 893   return JVMTI_ERROR_NONE;
 894 }
 895 
 896 jvmtiError
 897 JvmtiEnvBase::get_frame_count(JvmtiThreadState *state, jint *count_ptr) {
 898   assert((state != NULL),
 899          "JavaThread should create JvmtiThreadState before calling this method");
 900   *count_ptr = state->count_frames();
 901   return JVMTI_ERROR_NONE;
 902 }
 903 
 904 jvmtiError
 905 JvmtiEnvBase::get_frame_location(JavaThread *java_thread, jint depth,
 906                                  jmethodID* method_ptr, jlocation* location_ptr) {
 907 #ifdef ASSERT
 908   uint32_t debug_bits = 0;
 909 #endif
 910   Thread* current_thread = Thread::current();
 911   assert(java_thread->is_handshake_safe_for(current_thread),
 912          "call by myself or at handshake");
 913   ResourceMark rm(current_thread);
 914 
 915   vframe *vf = vframeForNoProcess(java_thread, depth);
 916   if (vf == NULL) {
 917     return JVMTI_ERROR_NO_MORE_FRAMES;
 918   }
 919 
 920   // vframeFor should return a java frame. If it doesn't
 921   // it means we've got an internal error and we return the
 922   // error in product mode. In debug mode we will instead
 923   // attempt to cast the vframe to a javaVFrame and will
 924   // cause an assertion/crash to allow further diagnosis.
 925 #ifdef PRODUCT
 926   if (!vf->is_java_frame()) {
 927     return JVMTI_ERROR_INTERNAL;
 928   }
 929 #endif
 930 
 931   HandleMark hm(current_thread);
 932   javaVFrame *jvf = javaVFrame::cast(vf);
 933   Method* method = jvf->method();
 934   if (method->is_native()) {
 935     *location_ptr = -1;
 936   } else {
 937     *location_ptr = jvf->bci();
 938   }
 939   *method_ptr = method->jmethod_id();
 940 
 941   return JVMTI_ERROR_NONE;
 942 }
 943 
 944 
 945 jvmtiError
 946 JvmtiEnvBase::get_object_monitor_usage(JavaThread* calling_thread, jobject object, jvmtiMonitorUsage* info_ptr) {
 947   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 948   Thread* current_thread = VMThread::vm_thread();
 949   assert(current_thread == Thread::current(), "must be");
 950 
 951   HandleMark hm(current_thread);
 952   Handle hobj;
 953 
 954   // Check arguments
 955   {
 956     oop mirror = JNIHandles::resolve_external_guard(object);
 957     NULL_CHECK(mirror, JVMTI_ERROR_INVALID_OBJECT);
 958     NULL_CHECK(info_ptr, JVMTI_ERROR_NULL_POINTER);
 959 
 960     hobj = Handle(current_thread, mirror);
 961   }
 962 
 963   ThreadsListHandle tlh(current_thread);
 964   JavaThread *owning_thread = NULL;
 965   ObjectMonitor *mon = NULL;
 966   jvmtiMonitorUsage ret = {
 967       NULL, 0, 0, NULL, 0, NULL
 968   };
 969 
 970   uint32_t debug_bits = 0;
 971   // first derive the object's owner and entry_count (if any)
 972   {
 973     // Revoke any biases before querying the mark word
 974     BiasedLocking::revoke_at_safepoint(hobj);
 975 
 976     address owner = NULL;
 977     {
 978       markWord mark = hobj()->mark();
 979 
 980       if (!mark.has_monitor()) {
 981         // this object has a lightweight monitor
 982 
 983         if (mark.has_locker()) {
 984           owner = (address)mark.locker(); // save the address of the Lock word
 985         }
 986         // implied else: no owner
 987       } else {
 988         // this object has a heavyweight monitor
 989         mon = mark.monitor();
 990 
 991         // The owner field of a heavyweight monitor may be NULL for no
 992         // owner, a JavaThread * or it may still be the address of the
 993         // Lock word in a JavaThread's stack. A monitor can be inflated
 994         // by a non-owning JavaThread, but only the owning JavaThread
 995         // can change the owner field from the Lock word to the
 996         // JavaThread * and it may not have done that yet.
 997         owner = (address)mon->owner();
 998       }
 999     }
1000 
1001     if (owner != NULL) {
1002       // This monitor is owned so we have to find the owning JavaThread.
1003       owning_thread = Threads::owning_thread_from_monitor_owner(tlh.list(), owner);
1004       assert(owning_thread != NULL, "owning JavaThread must not be NULL");
1005       Handle     th(current_thread, owning_thread->threadObj());
1006       ret.owner = (jthread)jni_reference(calling_thread, th);
1007     }
1008 
1009     if (owning_thread != NULL) {  // monitor is owned
1010       // The recursions field of a monitor does not reflect recursions
1011       // as lightweight locks before inflating the monitor are not included.
1012       // We have to count the number of recursive monitor entries the hard way.
1013       // We pass a handle to survive any GCs along the way.
1014       ret.entry_count = count_locked_objects(owning_thread, hobj);
1015     }
1016     // implied else: entry_count == 0
1017   }
1018 
1019   jint nWant = 0, nWait = 0;
1020   if (mon != NULL) {
1021     // this object has a heavyweight monitor
1022     nWant = mon->contentions(); // # of threads contending for monitor
1023     nWait = mon->waiters();     // # of threads in Object.wait()
1024     ret.waiter_count = nWant + nWait;
1025     ret.notify_waiter_count = nWait;
1026   } else {
1027     // this object has a lightweight monitor
1028     ret.waiter_count = 0;
1029     ret.notify_waiter_count = 0;
1030   }
1031 
1032   // Allocate memory for heavyweight and lightweight monitor.
1033   jvmtiError err;
1034   err = allocate(ret.waiter_count * sizeof(jthread *), (unsigned char**)&ret.waiters);
1035   if (err != JVMTI_ERROR_NONE) {
1036     return err;
1037   }
1038   err = allocate(ret.notify_waiter_count * sizeof(jthread *),
1039                  (unsigned char**)&ret.notify_waiters);
1040   if (err != JVMTI_ERROR_NONE) {
1041     deallocate((unsigned char*)ret.waiters);
1042     return err;
1043   }
1044 
1045   // now derive the rest of the fields
1046   if (mon != NULL) {
1047     // this object has a heavyweight monitor
1048 
1049     // Number of waiters may actually be less than the waiter count.
1050     // So NULL out memory so that unused memory will be NULL.
1051     memset(ret.waiters, 0, ret.waiter_count * sizeof(jthread *));
1052     memset(ret.notify_waiters, 0, ret.notify_waiter_count * sizeof(jthread *));
1053 
1054     if (ret.waiter_count > 0) {
1055       // we have contending and/or waiting threads
1056       if (nWant > 0) {
1057         // we have contending threads
1058         ResourceMark rm(current_thread);
1059         // get_pending_threads returns only java thread so we do not need to
1060         // check for non java threads.
1061         GrowableArray<JavaThread*>* wantList = Threads::get_pending_threads(tlh.list(), nWant, (address)mon);
1062         if (wantList->length() < nWant) {
1063           // robustness: the pending list has gotten smaller
1064           nWant = wantList->length();
1065         }
1066         for (int i = 0; i < nWant; i++) {
1067           JavaThread *pending_thread = wantList->at(i);
1068           Handle th(current_thread, pending_thread->threadObj());
1069           ret.waiters[i] = (jthread)jni_reference(calling_thread, th);
1070         }
1071       }
1072       if (nWait > 0) {
1073         // we have threads in Object.wait()
1074         int offset = nWant;  // add after any contending threads
1075         ObjectWaiter *waiter = mon->first_waiter();
1076         for (int i = 0, j = 0; i < nWait; i++) {
1077           if (waiter == NULL) {
1078             // robustness: the waiting list has gotten smaller
1079             nWait = j;
1080             break;
1081           }
1082           JavaThread *w = mon->thread_of_waiter(waiter);
1083           if (w != NULL) {
1084             // If the thread was found on the ObjectWaiter list, then
1085             // it has not been notified. This thread can't change the
1086             // state of the monitor so it doesn't need to be suspended.
1087             Handle th(current_thread, w->threadObj());
1088             ret.waiters[offset + j] = (jthread)jni_reference(calling_thread, th);
1089             ret.notify_waiters[j++] = (jthread)jni_reference(calling_thread, th);
1090           }
1091           waiter = mon->next_waiter(waiter);
1092         }
1093       }
1094     } // ThreadsListHandle is destroyed here.
1095 
1096     // Adjust count. nWant and nWait count values may be less than original.
1097     ret.waiter_count = nWant + nWait;
1098     ret.notify_waiter_count = nWait;
1099   } else {
1100     // this object has a lightweight monitor and we have nothing more
1101     // to do here because the defaults are just fine.
1102   }
1103 
1104   // we don't update return parameter unless everything worked
1105   *info_ptr = ret;
1106 
1107   return JVMTI_ERROR_NONE;
1108 }
1109 
1110 ResourceTracker::ResourceTracker(JvmtiEnv* env) {
1111   _env = env;
1112   _allocations = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<unsigned char*>(20, mtServiceability);
1113   _failed = false;
1114 }
1115 ResourceTracker::~ResourceTracker() {
1116   if (_failed) {
1117     for (int i=0; i<_allocations->length(); i++) {
1118       _env->deallocate(_allocations->at(i));
1119     }
1120   }
1121   delete _allocations;
1122 }
1123 
1124 jvmtiError ResourceTracker::allocate(jlong size, unsigned char** mem_ptr) {
1125   unsigned char *ptr;
1126   jvmtiError err = _env->allocate(size, &ptr);
1127   if (err == JVMTI_ERROR_NONE) {
1128     _allocations->append(ptr);
1129     *mem_ptr = ptr;
1130   } else {
1131     *mem_ptr = NULL;
1132     _failed = true;
1133   }
1134   return err;
1135  }
1136 
1137 unsigned char* ResourceTracker::allocate(jlong size) {
1138   unsigned char* ptr;
1139   allocate(size, &ptr);
1140   return ptr;
1141 }
1142 
1143 char* ResourceTracker::strdup(const char* str) {
1144   char *dup_str = (char*)allocate(strlen(str)+1);
1145   if (dup_str != NULL) {
1146     strcpy(dup_str, str);
1147   }
1148   return dup_str;
1149 }
1150 
1151 struct StackInfoNode {
1152   struct StackInfoNode *next;
1153   jvmtiStackInfo info;
1154 };
1155 
1156 // Create a jvmtiStackInfo inside a linked list node and create a
1157 // buffer for the frame information, both allocated as resource objects.
1158 // Fill in both the jvmtiStackInfo and the jvmtiFrameInfo.
1159 // Note that either or both of thr and thread_oop
1160 // may be null if the thread is new or has exited.
1161 void
1162 MultipleStackTracesCollector::fill_frames(jthread jt, JavaThread *thr, oop thread_oop) {
1163 #ifdef ASSERT
1164   Thread *current_thread = Thread::current();
1165   assert(SafepointSynchronize::is_at_safepoint() ||
1166          thr->is_handshake_safe_for(current_thread),
1167          "call by myself / at safepoint / at handshake");
1168 #endif
1169 
1170   jint state = 0;
1171   struct StackInfoNode *node = NEW_RESOURCE_OBJ(struct StackInfoNode);
1172   jvmtiStackInfo *infop = &(node->info);
1173   node->next = head();
1174   set_head(node);
1175   infop->frame_count = 0;
1176   infop->thread = jt;
1177 
1178   if (thread_oop != NULL) {
1179     // get most state bits
1180     state = (jint)java_lang_Thread::get_thread_status(thread_oop);
1181   }
1182 
1183   if (thr != NULL) {    // add more state bits if there is a JavaThead to query
1184     if (thr->is_suspended()) {
1185       state |= JVMTI_THREAD_STATE_SUSPENDED;
1186     }
1187     JavaThreadState jts = thr->thread_state();
1188     if (jts == _thread_in_native) {
1189       state |= JVMTI_THREAD_STATE_IN_NATIVE;
1190     }
1191     if (thr->is_interrupted(false)) {
1192       state |= JVMTI_THREAD_STATE_INTERRUPTED;
1193     }
1194   }
1195   infop->state = state;
1196 
1197   if (thr != NULL && (state & JVMTI_THREAD_STATE_ALIVE) != 0) {
1198     infop->frame_buffer = NEW_RESOURCE_ARRAY(jvmtiFrameInfo, max_frame_count());
1199     env()->get_stack_trace(thr, 0, max_frame_count(),
1200                            infop->frame_buffer, &(infop->frame_count));
1201   } else {
1202     infop->frame_buffer = NULL;
1203     infop->frame_count = 0;
1204   }
1205   _frame_count_total += infop->frame_count;
1206 }
1207 
1208 // Based on the stack information in the linked list, allocate memory
1209 // block to return and fill it from the info in the linked list.
1210 void
1211 MultipleStackTracesCollector::allocate_and_fill_stacks(jint thread_count) {
1212   // do I need to worry about alignment issues?
1213   jlong alloc_size =  thread_count       * sizeof(jvmtiStackInfo)
1214                     + _frame_count_total * sizeof(jvmtiFrameInfo);
1215   env()->allocate(alloc_size, (unsigned char **)&_stack_info);
1216 
1217   // pointers to move through the newly allocated space as it is filled in
1218   jvmtiStackInfo *si = _stack_info + thread_count;      // bottom of stack info
1219   jvmtiFrameInfo *fi = (jvmtiFrameInfo *)si;            // is the top of frame info
1220 
1221   // copy information in resource area into allocated buffer
1222   // insert stack info backwards since linked list is backwards
1223   // insert frame info forwards
1224   // walk the StackInfoNodes
1225   for (struct StackInfoNode *sin = head(); sin != NULL; sin = sin->next) {
1226     jint frame_count = sin->info.frame_count;
1227     size_t frames_size = frame_count * sizeof(jvmtiFrameInfo);
1228     --si;
1229     memcpy(si, &(sin->info), sizeof(jvmtiStackInfo));
1230     if (frames_size == 0) {
1231       si->frame_buffer = NULL;
1232     } else {
1233       memcpy(fi, sin->info.frame_buffer, frames_size);
1234       si->frame_buffer = fi;  // point to the new allocated copy of the frames
1235       fi += frame_count;
1236     }
1237   }
1238   assert(si == _stack_info, "the last copied stack info must be the first record");
1239   assert((unsigned char *)fi == ((unsigned char *)_stack_info) + alloc_size,
1240          "the last copied frame info must be the last record");
1241 }
1242 
1243 
1244 void
1245 VM_GetThreadListStackTraces::doit() {
1246   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1247 
1248   ResourceMark rm;
1249   ThreadsListHandle tlh;
1250   for (int i = 0; i < _thread_count; ++i) {
1251     jthread jt = _thread_list[i];
1252     JavaThread* java_thread = NULL;
1253     oop thread_oop = NULL;
1254     jvmtiError err = JvmtiExport::cv_external_thread_to_JavaThread(tlh.list(), jt, &java_thread, &thread_oop);
1255     if (err != JVMTI_ERROR_NONE) {
1256       // We got an error code so we don't have a JavaThread *, but
1257       // only return an error from here if we didn't get a valid
1258       // thread_oop.
1259       if (thread_oop == NULL) {
1260         _collector.set_result(err);
1261         return;
1262       }
1263       // We have a valid thread_oop.
1264     }
1265     _collector.fill_frames(jt, java_thread, thread_oop);
1266   }
1267   _collector.allocate_and_fill_stacks(_thread_count);
1268 }
1269 
1270 void
1271 GetSingleStackTraceClosure::do_thread(Thread *target) {
1272   JavaThread *jt = target->as_Java_thread();
1273   oop thread_oop = jt->threadObj();
1274 
1275   if (!jt->is_exiting() && thread_oop != NULL) {
1276     ResourceMark rm;
1277     _collector.fill_frames(_jthread, jt, thread_oop);
1278     _collector.allocate_and_fill_stacks(1);
1279   }
1280 }
1281 
1282 void
1283 VM_GetAllStackTraces::doit() {
1284   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1285 
1286   ResourceMark rm;
1287   _final_thread_count = 0;
1288   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
1289     oop thread_oop = jt->threadObj();
1290     if (thread_oop != NULL &&
1291         !jt->is_exiting() &&
1292         java_lang_Thread::is_alive(thread_oop) &&
1293         !jt->is_hidden_from_external_view()) {
1294       ++_final_thread_count;
1295       // Handle block of the calling thread is used to create local refs.
1296       _collector.fill_frames((jthread)JNIHandles::make_local(_calling_thread, thread_oop),
1297                              jt, thread_oop);
1298     }
1299   }
1300   _collector.allocate_and_fill_stacks(_final_thread_count);
1301 }
1302 
1303 // Verifies that the top frame is a java frame in an expected state.
1304 // Deoptimizes frame if needed.
1305 // Checks that the frame method signature matches the return type (tos).
1306 // HandleMark must be defined in the caller only.
1307 // It is to keep a ret_ob_h handle alive after return to the caller.
1308 jvmtiError
1309 JvmtiEnvBase::check_top_frame(Thread* current_thread, JavaThread* java_thread,
1310                               jvalue value, TosState tos, Handle* ret_ob_h) {
1311   ResourceMark rm(current_thread);
1312 
1313   vframe *vf = vframeForNoProcess(java_thread, 0);
1314   NULL_CHECK(vf, JVMTI_ERROR_NO_MORE_FRAMES);
1315 
1316   javaVFrame *jvf = (javaVFrame*) vf;
1317   if (!vf->is_java_frame() || jvf->method()->is_native()) {
1318     return JVMTI_ERROR_OPAQUE_FRAME;
1319   }
1320 
1321   // If the frame is a compiled one, need to deoptimize it.
1322   if (vf->is_compiled_frame()) {
1323     if (!vf->fr().can_be_deoptimized()) {
1324       return JVMTI_ERROR_OPAQUE_FRAME;
1325     }
1326     Deoptimization::deoptimize_frame(java_thread, jvf->fr().id());
1327   }
1328 
1329   // Get information about method return type
1330   Symbol* signature = jvf->method()->signature();
1331 
1332   ResultTypeFinder rtf(signature);
1333   TosState fr_tos = as_TosState(rtf.type());
1334   if (fr_tos != tos) {
1335     if (tos != itos || (fr_tos != btos && fr_tos != ztos && fr_tos != ctos && fr_tos != stos)) {
1336       return JVMTI_ERROR_TYPE_MISMATCH;
1337     }
1338   }
1339 
1340   // Check that the jobject class matches the return type signature.
1341   jobject jobj = value.l;
1342   if (tos == atos && jobj != NULL) { // NULL reference is allowed
1343     Handle ob_h(current_thread, JNIHandles::resolve_external_guard(jobj));
1344     NULL_CHECK(ob_h, JVMTI_ERROR_INVALID_OBJECT);
1345     Klass* ob_k = ob_h()->klass();
1346     NULL_CHECK(ob_k, JVMTI_ERROR_INVALID_OBJECT);
1347 
1348     // Method return type signature.
1349     char* ty_sign = 1 + strchr(signature->as_C_string(), JVM_SIGNATURE_ENDFUNC);
1350 
1351     if (!VM_GetOrSetLocal::is_assignable(ty_sign, ob_k, current_thread)) {
1352       return JVMTI_ERROR_TYPE_MISMATCH;
1353     }
1354     *ret_ob_h = ob_h;
1355   }
1356   return JVMTI_ERROR_NONE;
1357 } /* end check_top_frame */
1358 
1359 
1360 // ForceEarlyReturn<type> follows the PopFrame approach in many aspects.
1361 // Main difference is on the last stage in the interpreter.
1362 // The PopFrame stops method execution to continue execution
1363 // from the same method call instruction.
1364 // The ForceEarlyReturn forces return from method so the execution
1365 // continues at the bytecode following the method call.
1366 
1367 // java_thread - protected by ThreadsListHandle and pre-checked
1368 
1369 jvmtiError
1370 JvmtiEnvBase::force_early_return(JavaThread* java_thread, jvalue value, TosState tos) {
1371   // retrieve or create the state
1372   JvmtiThreadState* state = JvmtiThreadState::state_for(java_thread);
1373   if (state == NULL) {
1374     return JVMTI_ERROR_THREAD_NOT_ALIVE;
1375   }
1376 
1377   // Eagerly reallocate scalar replaced objects.
1378   JavaThread* current_thread = JavaThread::current();
1379   EscapeBarrier eb(true, current_thread, java_thread);
1380   if (!eb.deoptimize_objects(0)) {
1381     // Reallocation of scalar replaced objects failed -> return with error
1382     return JVMTI_ERROR_OUT_OF_MEMORY;
1383   }
1384 
1385   SetForceEarlyReturn op(state, value, tos);
1386   if (java_thread == current_thread) {
1387     op.doit(java_thread, true /* self */);
1388   } else {
1389     Handshake::execute(&op, java_thread);
1390   }
1391   return op.result();
1392 }
1393 
1394 void
1395 SetForceEarlyReturn::doit(Thread *target, bool self) {
1396   JavaThread* java_thread = target->as_Java_thread();
1397   Thread* current_thread = Thread::current();
1398   HandleMark   hm(current_thread);
1399 
1400   if (!self) {
1401     if (!java_thread->is_suspended()) {
1402       _result = JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1403       return;
1404     }
1405   }
1406 
1407   // Check to see if a ForceEarlyReturn was already in progress
1408   if (_state->is_earlyret_pending()) {
1409     // Probably possible for JVMTI clients to trigger this, but the
1410     // JPDA backend shouldn't allow this to happen
1411     _result = JVMTI_ERROR_INTERNAL;
1412     return;
1413   }
1414   {
1415     // The same as for PopFrame. Workaround bug:
1416     //  4812902: popFrame hangs if the method is waiting at a synchronize
1417     // Catch this condition and return an error to avoid hanging.
1418     // Now JVMTI spec allows an implementation to bail out with an opaque
1419     // frame error.
1420     OSThread* osThread = java_thread->osthread();
1421     if (osThread->get_state() == MONITOR_WAIT) {
1422       _result = JVMTI_ERROR_OPAQUE_FRAME;
1423       return;
1424     }
1425   }
1426 
1427   Handle ret_ob_h;
1428   _result = JvmtiEnvBase::check_top_frame(current_thread, java_thread, _value, _tos, &ret_ob_h);
1429   if (_result != JVMTI_ERROR_NONE) {
1430     return;
1431   }
1432   assert(_tos != atos || _value.l == NULL || ret_ob_h() != NULL,
1433          "return object oop must not be NULL if jobject is not NULL");
1434 
1435   // Update the thread state to reflect that the top frame must be
1436   // forced to return.
1437   // The current frame will be returned later when the suspended
1438   // thread is resumed and right before returning from VM to Java.
1439   // (see call_VM_base() in assembler_<cpu>.cpp).
1440 
1441   _state->set_earlyret_pending();
1442   _state->set_earlyret_oop(ret_ob_h());
1443   _state->set_earlyret_value(_value, _tos);
1444 
1445   // Set pending step flag for this early return.
1446   // It is cleared when next step event is posted.
1447   _state->set_pending_step_for_earlyret();
1448 }
1449 
1450 void
1451 JvmtiMonitorClosure::do_monitor(ObjectMonitor* mon) {
1452   if ( _error != JVMTI_ERROR_NONE) {
1453     // Error occurred in previous iteration so no need to add
1454     // to the list.
1455     return;
1456   }
1457   // Filter out on stack monitors collected during stack walk.
1458   oop obj = mon->object();
1459   bool found = false;
1460   for (int j = 0; j < _owned_monitors_list->length(); j++) {
1461     jobject jobj = ((jvmtiMonitorStackDepthInfo*)_owned_monitors_list->at(j))->monitor;
1462     oop check = JNIHandles::resolve(jobj);
1463     if (check == obj) {
1464       // On stack monitor already collected during the stack walk.
1465       found = true;
1466       break;
1467     }
1468   }
1469   if (found == false) {
1470     // This is off stack monitor (e.g. acquired via jni MonitorEnter).
1471     jvmtiError err;
1472     jvmtiMonitorStackDepthInfo *jmsdi;
1473     err = _env->allocate(sizeof(jvmtiMonitorStackDepthInfo), (unsigned char **)&jmsdi);
1474     if (err != JVMTI_ERROR_NONE) {
1475       _error = err;
1476       return;
1477     }
1478     Handle hobj(Thread::current(), obj);
1479     jmsdi->monitor = _env->jni_reference(_calling_thread, hobj);
1480     // stack depth is unknown for this monitor.
1481     jmsdi->stack_depth = -1;
1482     _owned_monitors_list->append(jmsdi);
1483   }
1484 }
1485 
1486 GrowableArray<OopHandle>* JvmtiModuleClosure::_tbl = NULL;
1487 
1488 void JvmtiModuleClosure::do_module(ModuleEntry* entry) {
1489   assert_locked_or_safepoint(Module_lock);
1490   OopHandle module = entry->module_handle();
1491   guarantee(module.resolve() != NULL, "module object is NULL");
1492   _tbl->push(module);
1493 }
1494 
1495 jvmtiError
1496 JvmtiModuleClosure::get_all_modules(JvmtiEnv* env, jint* module_count_ptr, jobject** modules_ptr) {
1497   ResourceMark rm;
1498   MutexLocker mcld(ClassLoaderDataGraph_lock);
1499   MutexLocker ml(Module_lock);
1500 
1501   _tbl = new GrowableArray<OopHandle>(77);
1502   if (_tbl == NULL) {
1503     return JVMTI_ERROR_OUT_OF_MEMORY;
1504   }
1505 
1506   // Iterate over all the modules loaded to the system.
1507   ClassLoaderDataGraph::modules_do(&do_module);
1508 
1509   jint len = _tbl->length();
1510   guarantee(len > 0, "at least one module must be present");
1511 
1512   jobject* array = (jobject*)env->jvmtiMalloc((jlong)(len * sizeof(jobject)));
1513   if (array == NULL) {
1514     return JVMTI_ERROR_OUT_OF_MEMORY;
1515   }
1516   for (jint idx = 0; idx < len; idx++) {
1517     array[idx] = JNIHandles::make_local(Thread::current(), _tbl->at(idx).resolve());
1518   }
1519   _tbl = NULL;
1520   *modules_ptr = array;
1521   *module_count_ptr = len;
1522   return JVMTI_ERROR_NONE;
1523 }
1524 
1525 void
1526 UpdateForPopTopFrameClosure::doit(Thread *target, bool self) {
1527   Thread* current_thread  = Thread::current();
1528   HandleMark hm(current_thread);
1529   JavaThread* java_thread = target->as_Java_thread();
1530   assert(java_thread == _state->get_thread(), "Must be");
1531 
1532   if (!self && !java_thread->is_suspended()) {
1533     _result = JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1534     return;
1535   }
1536 
1537   // Check to see if a PopFrame was already in progress
1538   if (java_thread->popframe_condition() != JavaThread::popframe_inactive) {
1539     // Probably possible for JVMTI clients to trigger this, but the
1540     // JPDA backend shouldn't allow this to happen
1541     _result = JVMTI_ERROR_INTERNAL;
1542     return;
1543   }
1544 
1545   // Was workaround bug
1546   //    4812902: popFrame hangs if the method is waiting at a synchronize
1547   // Catch this condition and return an error to avoid hanging.
1548   // Now JVMTI spec allows an implementation to bail out with an opaque frame error.
1549   OSThread* osThread = java_thread->osthread();
1550   if (osThread->get_state() == MONITOR_WAIT) {
1551     _result = JVMTI_ERROR_OPAQUE_FRAME;
1552     return;
1553   }
1554 
1555   ResourceMark rm(current_thread);
1556   // Check if there is more than one Java frame in this thread, that the top two frames
1557   // are Java (not native) frames, and that there is no intervening VM frame
1558   int frame_count = 0;
1559   bool is_interpreted[2];
1560   intptr_t *frame_sp[2];
1561   // The 2-nd arg of constructor is needed to stop iterating at java entry frame.
1562   for (vframeStream vfs(java_thread, true, false /* process_frames */); !vfs.at_end(); vfs.next()) {
1563     methodHandle mh(current_thread, vfs.method());
1564     if (mh->is_native()) {
1565       _result = JVMTI_ERROR_OPAQUE_FRAME;
1566       return;
1567     }
1568     is_interpreted[frame_count] = vfs.is_interpreted_frame();
1569     frame_sp[frame_count] = vfs.frame_id();
1570     if (++frame_count > 1) break;
1571   }
1572   if (frame_count < 2)  {
1573     // We haven't found two adjacent non-native Java frames on the top.
1574     // There can be two situations here:
1575     //  1. There are no more java frames
1576     //  2. Two top java frames are separated by non-java native frames
1577     if(JvmtiEnvBase::vframeForNoProcess(java_thread, 1) == NULL) {
1578       _result = JVMTI_ERROR_NO_MORE_FRAMES;
1579       return;
1580     } else {
1581       // Intervening non-java native or VM frames separate java frames.
1582       // Current implementation does not support this. See bug #5031735.
1583       // In theory it is possible to pop frames in such cases.
1584       _result = JVMTI_ERROR_OPAQUE_FRAME;
1585       return;
1586     }
1587   }
1588 
1589   // If any of the top 2 frames is a compiled one, need to deoptimize it
1590   for (int i = 0; i < 2; i++) {
1591     if (!is_interpreted[i]) {
1592       Deoptimization::deoptimize_frame(java_thread, frame_sp[i]);
1593     }
1594   }
1595 
1596   // Update the thread state to reflect that the top frame is popped
1597   // so that cur_stack_depth is maintained properly and all frameIDs
1598   // are invalidated.
1599   // The current frame will be popped later when the suspended thread
1600   // is resumed and right before returning from VM to Java.
1601   // (see call_VM_base() in assembler_<cpu>.cpp).
1602 
1603   // It's fine to update the thread state here because no JVMTI events
1604   // shall be posted for this PopFrame.
1605 
1606   if (!java_thread->is_exiting() && java_thread->threadObj() != NULL) {
1607     _state->update_for_pop_top_frame();
1608     java_thread->set_popframe_condition(JavaThread::popframe_pending_bit);
1609     // Set pending step flag for this popframe and it is cleared when next
1610     // step event is posted.
1611     _state->set_pending_step_for_popframe();
1612     _result = JVMTI_ERROR_NONE;
1613   }
1614 }
1615 
1616 void
1617 SetFramePopClosure::doit(Thread *target, bool self) {
1618   ResourceMark rm;
1619   JavaThread* java_thread = target->as_Java_thread();
1620 
1621   assert(_state->get_thread() == java_thread, "Must be");
1622 
1623   if (!self && !java_thread->is_suspended()) {
1624     _result = JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1625     return;
1626   }
1627 
1628   vframe *vf = JvmtiEnvBase::vframeForNoProcess(java_thread, _depth);
1629   if (vf == NULL) {
1630     _result = JVMTI_ERROR_NO_MORE_FRAMES;
1631     return;
1632   }
1633 
1634   if (!vf->is_java_frame() || ((javaVFrame*) vf)->method()->is_native()) {
1635     _result = JVMTI_ERROR_OPAQUE_FRAME;
1636     return;
1637   }
1638 
1639   assert(vf->frame_pointer() != NULL, "frame pointer mustn't be NULL");
1640   if (java_thread->is_exiting() || java_thread->threadObj() == NULL) {
1641     return; /* JVMTI_ERROR_THREAD_NOT_ALIVE (default) */
1642   }
1643   int frame_number = _state->count_frames() - _depth;
1644   _state->env_thread_state((JvmtiEnvBase*)_env)->set_frame_pop(frame_number);
1645   _result = JVMTI_ERROR_NONE;
1646 }
1647 
1648 void
1649 GetOwnedMonitorInfoClosure::do_thread(Thread *target) {
1650   JavaThread *jt = target->as_Java_thread();
1651   if (!jt->is_exiting() && (jt->threadObj() != NULL)) {
1652     _result = ((JvmtiEnvBase *)_env)->get_owned_monitors(_calling_thread,
1653                                                          jt,
1654                                                          _owned_monitors_list);
1655   }
1656 }
1657 
1658 void
1659 GetCurrentContendedMonitorClosure::do_thread(Thread *target) {
1660   JavaThread *jt = target->as_Java_thread();
1661   if (!jt->is_exiting() && (jt->threadObj() != NULL)) {
1662     _result = ((JvmtiEnvBase *)_env)->get_current_contended_monitor(_calling_thread,
1663                                                                     jt,
1664                                                                     _owned_monitor_ptr);
1665   }
1666 }
1667 
1668 void
1669 GetStackTraceClosure::do_thread(Thread *target) {
1670   JavaThread *jt = target->as_Java_thread();
1671   if (!jt->is_exiting() && jt->threadObj() != NULL) {
1672     _result = ((JvmtiEnvBase *)_env)->get_stack_trace(jt,
1673                                                       _start_depth, _max_count,
1674                                                       _frame_buffer, _count_ptr);
1675   }
1676 }
1677 
1678 void
1679 GetFrameCountClosure::do_thread(Thread *target) {
1680   JavaThread* jt = _state->get_thread();
1681   assert(target == jt, "just checking");
1682   if (!jt->is_exiting() && jt->threadObj() != NULL) {
1683     _result = ((JvmtiEnvBase*)_env)->get_frame_count(_state, _count_ptr);
1684   }
1685 }
1686 
1687 void
1688 GetFrameLocationClosure::do_thread(Thread *target) {
1689   JavaThread *jt = target->as_Java_thread();
1690   if (!jt->is_exiting() && jt->threadObj() != NULL) {
1691     _result = ((JvmtiEnvBase*)_env)->get_frame_location(jt, _depth,
1692                                                         _method_ptr, _location_ptr);
1693   }
1694 }