1 /*
   2  * Copyright (c) 2003, 2011, 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/systemDictionary.hpp"
  27 #include "jvmtifiles/jvmtiEnv.hpp"
  28 #include "oops/objArrayKlass.hpp"
  29 #include "oops/objArrayOop.hpp"
  30 #include "prims/jvmtiEnvBase.hpp"
  31 #include "prims/jvmtiEventController.inline.hpp"
  32 #include "prims/jvmtiExtensions.hpp"
  33 #include "prims/jvmtiImpl.hpp"
  34 #include "prims/jvmtiManageCapabilities.hpp"
  35 #include "prims/jvmtiTagMap.hpp"
  36 #include "prims/jvmtiThreadState.inline.hpp"
  37 #include "runtime/biasedLocking.hpp"
  38 #include "runtime/deoptimization.hpp"
  39 #include "runtime/interfaceSupport.hpp"
  40 #include "runtime/jfieldIDWorkaround.hpp"
  41 #include "runtime/objectMonitor.hpp"
  42 #include "runtime/objectMonitor.inline.hpp"
  43 #include "runtime/signature.hpp"
  44 #include "runtime/vframe.hpp"
  45 #include "runtime/vframe_hp.hpp"
  46 #include "runtime/vmThread.hpp"
  47 #include "runtime/vm_operations.hpp"
  48 
  49 ///////////////////////////////////////////////////////////////
  50 //
  51 // JvmtiEnvBase
  52 //
  53 
  54 JvmtiEnvBase* JvmtiEnvBase::_head_environment = NULL;
  55 
  56 bool JvmtiEnvBase::_globally_initialized = false;
  57 volatile bool JvmtiEnvBase::_needs_clean_up = false;
  58 
  59 jvmtiPhase JvmtiEnvBase::_phase = JVMTI_PHASE_PRIMORDIAL;
  60 
  61 volatile int JvmtiEnvBase::_dying_thread_env_iteration_count = 0;
  62 
  63 extern jvmtiInterface_1_ jvmti_Interface;
  64 extern jvmtiInterface_1_ jvmtiTrace_Interface;
  65 
  66 
  67 // perform initializations that must occur before any JVMTI environments
  68 // are released but which should only be initialized once (no matter
  69 // how many environments are created).
  70 void
  71 JvmtiEnvBase::globally_initialize() {
  72   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
  73   assert(_globally_initialized == false, "bad call");
  74 
  75   JvmtiManageCapabilities::initialize();
  76 
  77 #ifndef JVMTI_KERNEL
  78   // register extension functions and events
  79   JvmtiExtensions::register_extensions();
  80 #endif // !JVMTI_KERNEL
  81 
  82 #ifdef JVMTI_TRACE
  83   JvmtiTrace::initialize();
  84 #endif
  85 
  86   _globally_initialized = true;
  87 }
  88 
  89 
  90 void
  91 JvmtiEnvBase::initialize() {
  92   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
  93 
  94   // Add this environment to the end of the environment list (order is important)
  95   {
  96     // This block of code must not contain any safepoints, as list deallocation
  97     // (which occurs at a safepoint) cannot occur simultaneously with this list
  98     // addition.  Note: No_Safepoint_Verifier cannot, currently, be used before
  99     // threads exist.
 100     JvmtiEnvIterator it;
 101     JvmtiEnvBase *previous_env = NULL;
 102     for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
 103       previous_env = env;
 104     }
 105     if (previous_env == NULL) {
 106       _head_environment = this;
 107     } else {
 108       previous_env->set_next_environment(this);
 109     }
 110   }
 111 
 112   if (_globally_initialized == false) {
 113     globally_initialize();
 114   }
 115 }
 116 
 117 
 118 bool
 119 JvmtiEnvBase::is_valid() {
 120   jint value = 0;
 121 
 122   // This object might not be a JvmtiEnvBase so we can't assume
 123   // the _magic field is properly aligned. Get the value in a safe
 124   // way and then check against JVMTI_MAGIC.
 125 
 126   switch (sizeof(_magic)) {
 127   case 2:
 128     value = Bytes::get_native_u2((address)&_magic);
 129     break;
 130 
 131   case 4:
 132     value = Bytes::get_native_u4((address)&_magic);
 133     break;
 134 
 135   case 8:
 136     value = Bytes::get_native_u8((address)&_magic);
 137     break;
 138 
 139   default:
 140     guarantee(false, "_magic field is an unexpected size");
 141   }
 142 
 143   return value == JVMTI_MAGIC;
 144 }
 145 
 146 
 147 bool
 148 JvmtiEnvBase::use_version_1_0_semantics() {
 149   int major, minor, micro;
 150 
 151   JvmtiExport::decode_version_values(_version, &major, &minor, &micro);
 152   return major == 1 && minor == 0;  // micro version doesn't matter here
 153 }
 154 
 155 
 156 bool
 157 JvmtiEnvBase::use_version_1_1_semantics() {
 158   int major, minor, micro;
 159 
 160   JvmtiExport::decode_version_values(_version, &major, &minor, &micro);
 161   return major == 1 && minor == 1;  // micro version doesn't matter here
 162 }
 163 
 164 bool
 165 JvmtiEnvBase::use_version_1_2_semantics() {
 166   int major, minor, micro;
 167 
 168   JvmtiExport::decode_version_values(_version, &major, &minor, &micro);
 169   return major == 1 && minor == 2;  // micro version doesn't matter here
 170 }
 171 
 172 
 173 JvmtiEnvBase::JvmtiEnvBase(jint version) : _env_event_enable() {
 174   _version = version;
 175   _env_local_storage = NULL;
 176   _tag_map = NULL;
 177   _native_method_prefix_count = 0;
 178   _native_method_prefixes = NULL;
 179   _next = NULL;
 180   _class_file_load_hook_ever_enabled = false;
 181 
 182   // Moot since ClassFileLoadHook not yet enabled.
 183   // But "true" will give a more predictable ClassFileLoadHook behavior
 184   // for environment creation during ClassFileLoadHook.
 185   _is_retransformable = true;
 186 
 187   // all callbacks initially NULL
 188   memset(&_event_callbacks,0,sizeof(jvmtiEventCallbacks));
 189 
 190   // all capabilities initially off
 191   memset(&_current_capabilities, 0, sizeof(_current_capabilities));
 192 
 193   // all prohibited capabilities initially off
 194   memset(&_prohibited_capabilities, 0, sizeof(_prohibited_capabilities));
 195 
 196   _magic = JVMTI_MAGIC;
 197 
 198   JvmtiEventController::env_initialize((JvmtiEnv*)this);
 199 
 200 #ifdef JVMTI_TRACE
 201   _jvmti_external.functions = TraceJVMTI != NULL ? &jvmtiTrace_Interface : &jvmti_Interface;
 202 #else
 203   _jvmti_external.functions = &jvmti_Interface;
 204 #endif
 205 }
 206 
 207 
 208 void
 209 JvmtiEnvBase::dispose() {
 210 
 211 #ifdef JVMTI_TRACE
 212   JvmtiTrace::shutdown();
 213 #endif
 214 
 215   // Dispose of event info and let the event controller call us back
 216   // in a locked state (env_dispose, below)
 217   JvmtiEventController::env_dispose(this);
 218 }
 219 
 220 void
 221 JvmtiEnvBase::env_dispose() {
 222   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
 223 
 224   // We have been entered with all events disabled on this environment.
 225   // A race to re-enable events (by setting callbacks) is prevented by
 226   // checking for a valid environment when setting callbacks (while
 227   // holding the JvmtiThreadState_lock).
 228 
 229   // Mark as invalid.
 230   _magic = DISPOSED_MAGIC;
 231 
 232   // Relinquish all capabilities.
 233   jvmtiCapabilities *caps = get_capabilities();
 234   JvmtiManageCapabilities::relinquish_capabilities(caps, caps, caps);
 235 
 236   // Same situation as with events (see above)
 237   set_native_method_prefixes(0, NULL);
 238 
 239 #ifndef JVMTI_KERNEL
 240   JvmtiTagMap* tag_map_to_deallocate = _tag_map;
 241   set_tag_map(NULL);
 242   // A tag map can be big, deallocate it now
 243   if (tag_map_to_deallocate != NULL) {
 244     delete tag_map_to_deallocate;
 245   }
 246 #endif // !JVMTI_KERNEL
 247 
 248   _needs_clean_up = true;
 249 }
 250 
 251 
 252 JvmtiEnvBase::~JvmtiEnvBase() {
 253   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
 254 
 255   // There is a small window of time during which the tag map of a
 256   // disposed environment could have been reallocated.
 257   // Make sure it is gone.
 258 #ifndef JVMTI_KERNEL
 259   JvmtiTagMap* tag_map_to_deallocate = _tag_map;
 260   set_tag_map(NULL);
 261   // A tag map can be big, deallocate it now
 262   if (tag_map_to_deallocate != NULL) {
 263     delete tag_map_to_deallocate;
 264   }
 265 #endif // !JVMTI_KERNEL
 266 
 267   _magic = BAD_MAGIC;
 268 }
 269 
 270 
 271 void
 272 JvmtiEnvBase::periodic_clean_up() {
 273   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
 274 
 275   // JvmtiEnvBase reference is saved in JvmtiEnvThreadState. So
 276   // clean up JvmtiThreadState before deleting JvmtiEnv pointer.
 277   JvmtiThreadState::periodic_clean_up();
 278 
 279   // Unlink all invalid environments from the list of environments
 280   // and deallocate them
 281   JvmtiEnvIterator it;
 282   JvmtiEnvBase* previous_env = NULL;
 283   JvmtiEnvBase* env = it.first();
 284   while (env != NULL) {
 285     if (env->is_valid()) {
 286       previous_env = env;
 287       env = it.next(env);
 288     } else {
 289       // This one isn't valid, remove it from the list and deallocate it
 290       JvmtiEnvBase* defunct_env = env;
 291       env = it.next(env);
 292       if (previous_env == NULL) {
 293         _head_environment = env;
 294       } else {
 295         previous_env->set_next_environment(env);
 296       }
 297       delete defunct_env;
 298     }
 299   }
 300 
 301 }
 302 
 303 
 304 void
 305 JvmtiEnvBase::check_for_periodic_clean_up() {
 306   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
 307 
 308   class ThreadInsideIterationClosure: public ThreadClosure {
 309    private:
 310     bool _inside;
 311    public:
 312     ThreadInsideIterationClosure() : _inside(false) {};
 313 
 314     void do_thread(Thread* thread) {
 315       _inside |= thread->is_inside_jvmti_env_iteration();
 316     }
 317 
 318     bool is_inside_jvmti_env_iteration() {
 319       return _inside;
 320     }
 321   };
 322 
 323   if (_needs_clean_up) {
 324     // Check if we are currently iterating environment,
 325     // deallocation should not occur if we are
 326     ThreadInsideIterationClosure tiic;
 327     Threads::threads_do(&tiic);
 328     if (!tiic.is_inside_jvmti_env_iteration() &&
 329              !is_inside_dying_thread_env_iteration()) {
 330       _needs_clean_up = false;
 331       JvmtiEnvBase::periodic_clean_up();
 332     }
 333   }
 334 }
 335 
 336 
 337 void
 338 JvmtiEnvBase::record_first_time_class_file_load_hook_enabled() {
 339   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(),
 340          "sanity check");
 341 
 342   if (!_class_file_load_hook_ever_enabled) {
 343     _class_file_load_hook_ever_enabled = true;
 344 
 345     if (get_capabilities()->can_retransform_classes) {
 346       _is_retransformable = true;
 347     } else {
 348       _is_retransformable = false;
 349 
 350       // cannot add retransform capability after ClassFileLoadHook has been enabled
 351       get_prohibited_capabilities()->can_retransform_classes = 1;
 352     }
 353   }
 354 }
 355 
 356 
 357 void
 358 JvmtiEnvBase::record_class_file_load_hook_enabled() {
 359   if (!_class_file_load_hook_ever_enabled) {
 360     if (Threads::number_of_threads() == 0) {
 361       record_first_time_class_file_load_hook_enabled();
 362     } else {
 363       MutexLocker mu(JvmtiThreadState_lock);
 364       record_first_time_class_file_load_hook_enabled();
 365     }
 366   }
 367 }
 368 
 369 
 370 jvmtiError
 371 JvmtiEnvBase::set_native_method_prefixes(jint prefix_count, char** prefixes) {
 372   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(),
 373          "sanity check");
 374 
 375   int old_prefix_count = get_native_method_prefix_count();
 376   char **old_prefixes = get_native_method_prefixes();
 377 
 378   // allocate and install the new prefixex
 379   if (prefix_count == 0 || !is_valid()) {
 380     _native_method_prefix_count = 0;
 381     _native_method_prefixes = NULL;
 382   } else {
 383     // there are prefixes, allocate an array to hold them, and fill it
 384     char** new_prefixes = (char**)os::malloc((prefix_count) * sizeof(char*));
 385     if (new_prefixes == NULL) {
 386       return JVMTI_ERROR_OUT_OF_MEMORY;
 387     }
 388     for (int i = 0; i < prefix_count; i++) {
 389       char* prefix = prefixes[i];
 390       if (prefix == NULL) {
 391         for (int j = 0; j < (i-1); j++) {
 392           os::free(new_prefixes[j]);
 393         }
 394         os::free(new_prefixes);
 395         return JVMTI_ERROR_NULL_POINTER;
 396       }
 397       prefix = os::strdup(prefixes[i]);
 398       if (prefix == NULL) {
 399         for (int j = 0; j < (i-1); j++) {
 400           os::free(new_prefixes[j]);
 401         }
 402         os::free(new_prefixes);
 403         return JVMTI_ERROR_OUT_OF_MEMORY;
 404       }
 405       new_prefixes[i] = prefix;
 406     }
 407     _native_method_prefix_count = prefix_count;
 408     _native_method_prefixes = new_prefixes;
 409   }
 410 
 411   // now that we know the new prefixes have been successfully installed we can
 412   // safely remove the old ones
 413   if (old_prefix_count != 0) {
 414     for (int i = 0; i < old_prefix_count; i++) {
 415       os::free(old_prefixes[i]);
 416     }
 417     os::free(old_prefixes);
 418   }
 419 
 420   return JVMTI_ERROR_NONE;
 421 }
 422 
 423 
 424 // Collect all the prefixes which have been set in any JVM TI environments
 425 // by the SetNativeMethodPrefix(es) functions.  Be sure to maintain the
 426 // order of environments and the order of prefixes within each environment.
 427 // Return in a resource allocated array.
 428 char**
 429 JvmtiEnvBase::get_all_native_method_prefixes(int* count_ptr) {
 430   assert(Threads::number_of_threads() == 0 ||
 431          SafepointSynchronize::is_at_safepoint() ||
 432          JvmtiThreadState_lock->is_locked(),
 433          "sanity check");
 434 
 435   int total_count = 0;
 436   GrowableArray<char*>* prefix_array =new GrowableArray<char*>(5);
 437 
 438   JvmtiEnvIterator it;
 439   for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
 440     int prefix_count = env->get_native_method_prefix_count();
 441     char** prefixes = env->get_native_method_prefixes();
 442     for (int j = 0; j < prefix_count; j++) {
 443       // retrieve a prefix and so that it is safe against asynchronous changes
 444       // copy it into the resource area
 445       char* prefix = prefixes[j];
 446       char* prefix_copy = NEW_RESOURCE_ARRAY(char, strlen(prefix)+1);
 447       strcpy(prefix_copy, prefix);
 448       prefix_array->at_put_grow(total_count++, prefix_copy);
 449     }
 450   }
 451 
 452   char** all_prefixes = NEW_RESOURCE_ARRAY(char*, total_count);
 453   char** p = all_prefixes;
 454   for (int i = 0; i < total_count; ++i) {
 455     *p++ = prefix_array->at(i);
 456   }
 457   *count_ptr = total_count;
 458   return all_prefixes;
 459 }
 460 
 461 void
 462 JvmtiEnvBase::set_event_callbacks(const jvmtiEventCallbacks* callbacks,
 463                                                jint size_of_callbacks) {
 464   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
 465 
 466   size_t byte_cnt = sizeof(jvmtiEventCallbacks);
 467 
 468   // clear in either case to be sure we got any gap between sizes
 469   memset(&_event_callbacks, 0, byte_cnt);
 470 
 471   // Now that JvmtiThreadState_lock is held, prevent a possible race condition where events
 472   // are re-enabled by a call to set event callbacks where the DisposeEnvironment
 473   // occurs after the boiler-plate environment check and before the lock is acquired.
 474   if (callbacks != NULL && is_valid()) {
 475     if (size_of_callbacks < (jint)byte_cnt) {
 476       byte_cnt = size_of_callbacks;
 477     }
 478     memcpy(&_event_callbacks, callbacks, byte_cnt);
 479   }
 480 }
 481 
 482 // Called from JVMTI entry points which perform stack walking. If the
 483 // associated JavaThread is the current thread, then wait_for_suspend
 484 // is not used. Otherwise, it determines if we should wait for the
 485 // "other" thread to complete external suspension. (NOTE: in future
 486 // releases the suspension mechanism should be reimplemented so this
 487 // is not necessary.)
 488 //
 489 bool
 490 JvmtiEnvBase::is_thread_fully_suspended(JavaThread* thr, bool wait_for_suspend, uint32_t *bits) {
 491   // "other" threads require special handling
 492   if (thr != JavaThread::current()) {
 493     if (wait_for_suspend) {
 494       // We are allowed to wait for the external suspend to complete
 495       // so give the other thread a chance to get suspended.
 496       if (!thr->wait_for_ext_suspend_completion(SuspendRetryCount,
 497           SuspendRetryDelay, bits)) {
 498         // didn't make it so let the caller know
 499         return false;
 500       }
 501     }
 502     // We aren't allowed to wait for the external suspend to complete
 503     // so if the other thread isn't externally suspended we need to
 504     // let the caller know.
 505     else if (!thr->is_ext_suspend_completed_with_lock(bits)) {
 506       return false;
 507     }
 508   }
 509 
 510   return true;
 511 }
 512 
 513 
 514 // In the fullness of time, all users of the method should instead
 515 // directly use allocate, besides being cleaner and faster, this will
 516 // mean much better out of memory handling
 517 unsigned char *
 518 JvmtiEnvBase::jvmtiMalloc(jlong size) {
 519   unsigned char* mem;
 520   jvmtiError result = allocate(size, &mem);
 521   assert(result == JVMTI_ERROR_NONE, "Allocate failed");
 522   return mem;
 523 }
 524 
 525 
 526 //
 527 // Threads
 528 //
 529 
 530 jobject *
 531 JvmtiEnvBase::new_jobjectArray(int length, Handle *handles) {
 532   if (length == 0) {
 533     return NULL;
 534   }
 535 
 536   jobject *objArray = (jobject *) jvmtiMalloc(sizeof(jobject) * length);
 537   NULL_CHECK(objArray, NULL);
 538 
 539   for (int i=0; i<length; i++) {
 540     objArray[i] = jni_reference(handles[i]);
 541   }
 542   return objArray;
 543 }
 544 
 545 jthread *
 546 JvmtiEnvBase::new_jthreadArray(int length, Handle *handles) {
 547   return (jthread *) new_jobjectArray(length,handles);
 548 }
 549 
 550 jthreadGroup *
 551 JvmtiEnvBase::new_jthreadGroupArray(int length, Handle *handles) {
 552   return (jthreadGroup *) new_jobjectArray(length,handles);
 553 }
 554 
 555 
 556 JavaThread *
 557 JvmtiEnvBase::get_JavaThread(jthread jni_thread) {
 558   oop t = JNIHandles::resolve_external_guard(jni_thread);
 559   if (t == NULL || !t->is_a(SystemDictionary::Thread_klass())) {
 560     return NULL;
 561   }
 562   // The following returns NULL if the thread has not yet run or is in
 563   // process of exiting
 564   return java_lang_Thread::thread(t);
 565 }
 566 
 567 
 568 // update the access_flags for the field in the klass
 569 void
 570 JvmtiEnvBase::update_klass_field_access_flag(fieldDescriptor *fd) {
 571   instanceKlass* ik = instanceKlass::cast(fd->field_holder());
 572   typeArrayOop fields = ik->fields();
 573   fields->ushort_at_put(fd->index(), (jushort)fd->access_flags().as_short());
 574 }
 575 
 576 
 577 // return the vframe on the specified thread and depth, NULL if no such frame
 578 vframe*
 579 JvmtiEnvBase::vframeFor(JavaThread* java_thread, jint depth) {
 580   if (!java_thread->has_last_Java_frame()) {
 581     return NULL;
 582   }
 583   RegisterMap reg_map(java_thread);
 584   vframe *vf = java_thread->last_java_vframe(&reg_map);
 585   int d = 0;
 586   while ((vf != NULL) && (d < depth)) {
 587     vf = vf->java_sender();
 588     d++;
 589   }
 590   return vf;
 591 }
 592 
 593 
 594 //
 595 // utilities: JNI objects
 596 //
 597 
 598 
 599 jclass
 600 JvmtiEnvBase::get_jni_class_non_null(klassOop k) {
 601   assert(k != NULL, "k != NULL");
 602   return (jclass)jni_reference(Klass::cast(k)->java_mirror());
 603 }
 604 
 605 #ifndef JVMTI_KERNEL
 606 
 607 //
 608 // Field Information
 609 //
 610 
 611 bool
 612 JvmtiEnvBase::get_field_descriptor(klassOop k, jfieldID field, fieldDescriptor* fd) {
 613   if (!jfieldIDWorkaround::is_valid_jfieldID(k, field)) {
 614     return false;
 615   }
 616   bool found = false;
 617   if (jfieldIDWorkaround::is_static_jfieldID(field)) {
 618     JNIid* id = jfieldIDWorkaround::from_static_jfieldID(field);
 619     found = id->find_local_field(fd);
 620   } else {
 621     // Non-static field. The fieldID is really the offset of the field within the object.
 622     int offset = jfieldIDWorkaround::from_instance_jfieldID(k, field);
 623     found = instanceKlass::cast(k)->find_field_from_offset(offset, false, fd);
 624   }
 625   return found;
 626 }
 627 
 628 //
 629 // Object Monitor Information
 630 //
 631 
 632 //
 633 // Count the number of objects for a lightweight monitor. The hobj
 634 // parameter is object that owns the monitor so this routine will
 635 // count the number of times the same object was locked by frames
 636 // in java_thread.
 637 //
 638 jint
 639 JvmtiEnvBase::count_locked_objects(JavaThread *java_thread, Handle hobj) {
 640   jint ret = 0;
 641   if (!java_thread->has_last_Java_frame()) {
 642     return ret;  // no Java frames so no monitors
 643   }
 644 
 645   ResourceMark rm;
 646   HandleMark   hm;
 647   RegisterMap  reg_map(java_thread);
 648 
 649   for(javaVFrame *jvf=java_thread->last_java_vframe(&reg_map); jvf != NULL;
 650                                                  jvf = jvf->java_sender()) {
 651     GrowableArray<MonitorInfo*>* mons = jvf->monitors();
 652     if (!mons->is_empty()) {
 653       for (int i = 0; i < mons->length(); i++) {
 654         MonitorInfo *mi = mons->at(i);
 655         if (mi->owner_is_scalar_replaced()) continue;
 656 
 657         // see if owner of the monitor is our object
 658         if (mi->owner() != NULL && mi->owner() == hobj()) {
 659           ret++;
 660         }
 661       }
 662     }
 663   }
 664   return ret;
 665 }
 666 
 667 
 668 
 669 jvmtiError
 670 JvmtiEnvBase::get_current_contended_monitor(JavaThread *calling_thread, JavaThread *java_thread, jobject *monitor_ptr) {
 671 #ifdef ASSERT
 672   uint32_t debug_bits = 0;
 673 #endif
 674   assert((SafepointSynchronize::is_at_safepoint() ||
 675           is_thread_fully_suspended(java_thread, false, &debug_bits)),
 676          "at safepoint or target thread is suspended");
 677   oop obj = NULL;
 678   ObjectMonitor *mon = java_thread->current_waiting_monitor();
 679   if (mon == NULL) {
 680     // thread is not doing an Object.wait() call
 681     mon = java_thread->current_pending_monitor();
 682     if (mon != NULL) {
 683       // The thread is trying to enter() or raw_enter() an ObjectMonitor.
 684       obj = (oop)mon->object();
 685       // If obj == NULL, then ObjectMonitor is raw which doesn't count
 686       // as contended for this API
 687     }
 688     // implied else: no contended ObjectMonitor
 689   } else {
 690     // thread is doing an Object.wait() call
 691     obj = (oop)mon->object();
 692     assert(obj != NULL, "Object.wait() should have an object");
 693   }
 694 
 695   if (obj == NULL) {
 696     *monitor_ptr = NULL;
 697   } else {
 698     HandleMark hm;
 699     Handle     hobj(obj);
 700     *monitor_ptr = jni_reference(calling_thread, hobj);
 701   }
 702   return JVMTI_ERROR_NONE;
 703 }
 704 
 705 
 706 jvmtiError
 707 JvmtiEnvBase::get_owned_monitors(JavaThread *calling_thread, JavaThread* java_thread,
 708                                  GrowableArray<jvmtiMonitorStackDepthInfo*> *owned_monitors_list) {
 709   jvmtiError err = JVMTI_ERROR_NONE;
 710 #ifdef ASSERT
 711   uint32_t debug_bits = 0;
 712 #endif
 713   assert((SafepointSynchronize::is_at_safepoint() ||
 714           is_thread_fully_suspended(java_thread, false, &debug_bits)),
 715          "at safepoint or target thread is suspended");
 716 
 717   if (java_thread->has_last_Java_frame()) {
 718     ResourceMark rm;
 719     HandleMark   hm;
 720     RegisterMap  reg_map(java_thread);
 721 
 722     int depth = 0;
 723     for (javaVFrame *jvf = java_thread->last_java_vframe(&reg_map); jvf != NULL;
 724          jvf = jvf->java_sender()) {
 725       if (depth++ < MaxJavaStackTraceDepth) {  // check for stack too deep
 726         // add locked objects for this frame into list
 727         err = get_locked_objects_in_frame(calling_thread, java_thread, jvf, owned_monitors_list, depth-1);
 728         if (err != JVMTI_ERROR_NONE) {
 729           return err;
 730         }
 731       }
 732     }
 733   }
 734 
 735   // Get off stack monitors. (e.g. acquired via jni MonitorEnter).
 736   JvmtiMonitorClosure jmc(java_thread, calling_thread, owned_monitors_list, this);
 737   ObjectSynchronizer::monitors_iterate(&jmc);
 738   err = jmc.error();
 739 
 740   return err;
 741 }
 742 
 743 // Save JNI local handles for any objects that this frame owns.
 744 jvmtiError
 745 JvmtiEnvBase::get_locked_objects_in_frame(JavaThread* calling_thread, JavaThread* java_thread,
 746                                  javaVFrame *jvf, GrowableArray<jvmtiMonitorStackDepthInfo*>* owned_monitors_list, int stack_depth) {
 747   jvmtiError err = JVMTI_ERROR_NONE;
 748   ResourceMark rm;
 749 
 750   GrowableArray<MonitorInfo*>* mons = jvf->monitors();
 751   if (mons->is_empty()) {
 752     return err;  // this javaVFrame holds no monitors
 753   }
 754 
 755   HandleMark hm;
 756   oop wait_obj = NULL;
 757   {
 758     // save object of current wait() call (if any) for later comparison
 759     ObjectMonitor *mon = java_thread->current_waiting_monitor();
 760     if (mon != NULL) {
 761       wait_obj = (oop)mon->object();
 762     }
 763   }
 764   oop pending_obj = NULL;
 765   {
 766     // save object of current enter() call (if any) for later comparison
 767     ObjectMonitor *mon = java_thread->current_pending_monitor();
 768     if (mon != NULL) {
 769       pending_obj = (oop)mon->object();
 770     }
 771   }
 772 
 773   for (int i = 0; i < mons->length(); i++) {
 774     MonitorInfo *mi = mons->at(i);
 775 
 776     if (mi->owner_is_scalar_replaced()) continue;
 777 
 778     oop obj = mi->owner();
 779     if (obj == NULL) {
 780       // this monitor doesn't have an owning object so skip it
 781       continue;
 782     }
 783 
 784     if (wait_obj == obj) {
 785       // the thread is waiting on this monitor so it isn't really owned
 786       continue;
 787     }
 788 
 789     if (pending_obj == obj) {
 790       // the thread is pending on this monitor so it isn't really owned
 791       continue;
 792     }
 793 
 794     if (owned_monitors_list->length() > 0) {
 795       // Our list has at least one object on it so we have to check
 796       // for recursive object locking
 797       bool found = false;
 798       for (int j = 0; j < owned_monitors_list->length(); j++) {
 799         jobject jobj = ((jvmtiMonitorStackDepthInfo*)owned_monitors_list->at(j))->monitor;
 800         oop check = JNIHandles::resolve(jobj);
 801         if (check == obj) {
 802           found = true;  // we found the object
 803           break;
 804         }
 805       }
 806 
 807       if (found) {
 808         // already have this object so don't include it
 809         continue;
 810       }
 811     }
 812 
 813     // add the owning object to our list
 814     jvmtiMonitorStackDepthInfo *jmsdi;
 815     err = allocate(sizeof(jvmtiMonitorStackDepthInfo), (unsigned char **)&jmsdi);
 816     if (err != JVMTI_ERROR_NONE) {
 817         return err;
 818     }
 819     Handle hobj(obj);
 820     jmsdi->monitor = jni_reference(calling_thread, hobj);
 821     jmsdi->stack_depth = stack_depth;
 822     owned_monitors_list->append(jmsdi);
 823   }
 824 
 825   return err;
 826 }
 827 
 828 jvmtiError
 829 JvmtiEnvBase::get_stack_trace(JavaThread *java_thread,
 830                               jint start_depth, jint max_count,
 831                               jvmtiFrameInfo* frame_buffer, jint* count_ptr) {
 832 #ifdef ASSERT
 833   uint32_t debug_bits = 0;
 834 #endif
 835   assert((SafepointSynchronize::is_at_safepoint() ||
 836           is_thread_fully_suspended(java_thread, false, &debug_bits)),
 837          "at safepoint or target thread is suspended");
 838   int count = 0;
 839   if (java_thread->has_last_Java_frame()) {
 840     RegisterMap reg_map(java_thread);
 841     Thread* current_thread = Thread::current();
 842     ResourceMark rm(current_thread);
 843     javaVFrame *jvf = java_thread->last_java_vframe(&reg_map);
 844     HandleMark hm(current_thread);
 845     if (start_depth != 0) {
 846       if (start_depth > 0) {
 847         for (int j = 0; j < start_depth && jvf != NULL; j++) {
 848           jvf = jvf->java_sender();
 849         }
 850         if (jvf == NULL) {
 851           // start_depth is deeper than the stack depth
 852           return JVMTI_ERROR_ILLEGAL_ARGUMENT;
 853         }
 854       } else { // start_depth < 0
 855         // we are referencing the starting depth based on the oldest
 856         // part of the stack.
 857         // optimize to limit the number of times that java_sender() is called
 858         javaVFrame *jvf_cursor = jvf;
 859         javaVFrame *jvf_prev = NULL;
 860         javaVFrame *jvf_prev_prev;
 861         int j = 0;
 862         while (jvf_cursor != NULL) {
 863           jvf_prev_prev = jvf_prev;
 864           jvf_prev = jvf_cursor;
 865           for (j = 0; j > start_depth && jvf_cursor != NULL; j--) {
 866             jvf_cursor = jvf_cursor->java_sender();
 867           }
 868         }
 869         if (j == start_depth) {
 870           // previous pointer is exactly where we want to start
 871           jvf = jvf_prev;
 872         } else {
 873           // we need to back up further to get to the right place
 874           if (jvf_prev_prev == NULL) {
 875             // the -start_depth is greater than the stack depth
 876             return JVMTI_ERROR_ILLEGAL_ARGUMENT;
 877           }
 878           // j now is the number of frames on the stack starting with
 879           // jvf_prev, we start from jvf_prev_prev and move older on
 880           // the stack that many, the result is -start_depth frames
 881           // remaining.
 882           jvf = jvf_prev_prev;
 883           for (; j < 0; j++) {
 884             jvf = jvf->java_sender();
 885           }
 886         }
 887       }
 888     }
 889     for (; count < max_count && jvf != NULL; count++) {
 890       frame_buffer[count].method = jvf->method()->jmethod_id();
 891       frame_buffer[count].location = (jvf->method()->is_native() ? -1 : jvf->bci());
 892       jvf = jvf->java_sender();
 893     }
 894   } else {
 895     if (start_depth != 0) {
 896       // no frames and there is a starting depth
 897       return JVMTI_ERROR_ILLEGAL_ARGUMENT;
 898     }
 899   }
 900   *count_ptr = count;
 901   return JVMTI_ERROR_NONE;
 902 }
 903 
 904 jvmtiError
 905 JvmtiEnvBase::get_frame_count(JvmtiThreadState *state, jint *count_ptr) {
 906   assert((state != NULL),
 907          "JavaThread should create JvmtiThreadState before calling this method");
 908   *count_ptr = state->count_frames();
 909   return JVMTI_ERROR_NONE;
 910 }
 911 
 912 jvmtiError
 913 JvmtiEnvBase::get_frame_location(JavaThread *java_thread, jint depth,
 914                                  jmethodID* method_ptr, jlocation* location_ptr) {
 915 #ifdef ASSERT
 916   uint32_t debug_bits = 0;
 917 #endif
 918   assert((SafepointSynchronize::is_at_safepoint() ||
 919           is_thread_fully_suspended(java_thread, false, &debug_bits)),
 920          "at safepoint or target thread is suspended");
 921   Thread* current_thread = Thread::current();
 922   ResourceMark rm(current_thread);
 923 
 924   vframe *vf = vframeFor(java_thread, depth);
 925   if (vf == NULL) {
 926     return JVMTI_ERROR_NO_MORE_FRAMES;
 927   }
 928 
 929   // vframeFor should return a java frame. If it doesn't
 930   // it means we've got an internal error and we return the
 931   // error in product mode. In debug mode we will instead
 932   // attempt to cast the vframe to a javaVFrame and will
 933   // cause an assertion/crash to allow further diagnosis.
 934 #ifdef PRODUCT
 935   if (!vf->is_java_frame()) {
 936     return JVMTI_ERROR_INTERNAL;
 937   }
 938 #endif
 939 
 940   HandleMark hm(current_thread);
 941   javaVFrame *jvf = javaVFrame::cast(vf);
 942   methodOop method = jvf->method();
 943   if (method->is_native()) {
 944     *location_ptr = -1;
 945   } else {
 946     *location_ptr = jvf->bci();
 947   }
 948   *method_ptr = method->jmethod_id();
 949 
 950   return JVMTI_ERROR_NONE;
 951 }
 952 
 953 
 954 jvmtiError
 955 JvmtiEnvBase::get_object_monitor_usage(JavaThread* calling_thread, jobject object, jvmtiMonitorUsage* info_ptr) {
 956   HandleMark hm;
 957   Handle hobj;
 958 
 959   bool at_safepoint = SafepointSynchronize::is_at_safepoint();
 960 
 961   // Check arguments
 962   {
 963     oop mirror = JNIHandles::resolve_external_guard(object);
 964     NULL_CHECK(mirror, JVMTI_ERROR_INVALID_OBJECT);
 965     NULL_CHECK(info_ptr, JVMTI_ERROR_NULL_POINTER);
 966 
 967     hobj = Handle(mirror);
 968   }
 969 
 970   JavaThread *owning_thread = NULL;
 971   ObjectMonitor *mon = NULL;
 972   jvmtiMonitorUsage ret = {
 973       NULL, 0, 0, NULL, 0, NULL
 974   };
 975 
 976   uint32_t debug_bits = 0;
 977   // first derive the object's owner and entry_count (if any)
 978   {
 979     // Revoke any biases before querying the mark word
 980     if (SafepointSynchronize::is_at_safepoint()) {
 981       BiasedLocking::revoke_at_safepoint(hobj);
 982     } else {
 983       BiasedLocking::revoke_and_rebias(hobj, false, calling_thread);
 984     }
 985 
 986     address owner = NULL;
 987     {
 988       markOop mark = hobj()->mark();
 989 
 990       if (!mark->has_monitor()) {
 991         // this object has a lightweight monitor
 992 
 993         if (mark->has_locker()) {
 994           owner = (address)mark->locker(); // save the address of the Lock word
 995         }
 996         // implied else: no owner
 997       } else {
 998         // this object has a heavyweight monitor
 999         mon = mark->monitor();
1000 
1001         // The owner field of a heavyweight monitor may be NULL for no
1002         // owner, a JavaThread * or it may still be the address of the
1003         // Lock word in a JavaThread's stack. A monitor can be inflated
1004         // by a non-owning JavaThread, but only the owning JavaThread
1005         // can change the owner field from the Lock word to the
1006         // JavaThread * and it may not have done that yet.
1007         owner = (address)mon->owner();
1008       }
1009     }
1010 
1011     if (owner != NULL) {
1012       // This monitor is owned so we have to find the owning JavaThread.
1013       // Since owning_thread_from_monitor_owner() grabs a lock, GC can
1014       // move our object at this point. However, our owner value is safe
1015       // since it is either the Lock word on a stack or a JavaThread *.
1016       owning_thread = Threads::owning_thread_from_monitor_owner(owner, !at_safepoint);
1017       assert(owning_thread != NULL, "sanity check");
1018       if (owning_thread != NULL) {  // robustness
1019         // The monitor's owner either has to be the current thread, at safepoint
1020         // or it has to be suspended. Any of these conditions will prevent both
1021         // contending and waiting threads from modifying the state of
1022         // the monitor.
1023         if (!at_safepoint && !JvmtiEnv::is_thread_fully_suspended(owning_thread, true, &debug_bits)) {
1024           return JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1025         }
1026         HandleMark hm;
1027         Handle     th(owning_thread->threadObj());
1028         ret.owner = (jthread)jni_reference(calling_thread, th);
1029       }
1030       // implied else: no owner
1031     }
1032 
1033     if (owning_thread != NULL) {  // monitor is owned
1034       if ((address)owning_thread == owner) {
1035         // the owner field is the JavaThread *
1036         assert(mon != NULL,
1037           "must have heavyweight monitor with JavaThread * owner");
1038         ret.entry_count = mon->recursions() + 1;
1039       } else {
1040         // The owner field is the Lock word on the JavaThread's stack
1041         // so the recursions field is not valid. We have to count the
1042         // number of recursive monitor entries the hard way. We pass
1043         // a handle to survive any GCs along the way.
1044         ResourceMark rm;
1045         ret.entry_count = count_locked_objects(owning_thread, hobj);
1046       }
1047     }
1048     // implied else: entry_count == 0
1049   }
1050 
1051   int nWant,nWait;
1052   if (mon != NULL) {
1053     // this object has a heavyweight monitor
1054     nWant = mon->contentions(); // # of threads contending for monitor
1055     nWait = mon->waiters();     // # of threads in Object.wait()
1056     ret.waiter_count = nWant + nWait;
1057     ret.notify_waiter_count = nWait;
1058   } else {
1059     // this object has a lightweight monitor
1060     ret.waiter_count = 0;
1061     ret.notify_waiter_count = 0;
1062   }
1063 
1064   // Allocate memory for heavyweight and lightweight monitor.
1065   jvmtiError err;
1066   err = allocate(ret.waiter_count * sizeof(jthread *), (unsigned char**)&ret.waiters);
1067   if (err != JVMTI_ERROR_NONE) {
1068     return err;
1069   }
1070   err = allocate(ret.notify_waiter_count * sizeof(jthread *),
1071                  (unsigned char**)&ret.notify_waiters);
1072   if (err != JVMTI_ERROR_NONE) {
1073     deallocate((unsigned char*)ret.waiters);
1074     return err;
1075   }
1076 
1077   // now derive the rest of the fields
1078   if (mon != NULL) {
1079     // this object has a heavyweight monitor
1080 
1081     // Number of waiters may actually be less than the waiter count.
1082     // So NULL out memory so that unused memory will be NULL.
1083     memset(ret.waiters, 0, ret.waiter_count * sizeof(jthread *));
1084     memset(ret.notify_waiters, 0, ret.notify_waiter_count * sizeof(jthread *));
1085 
1086     if (ret.waiter_count > 0) {
1087       // we have contending and/or waiting threads
1088       HandleMark hm;
1089       if (nWant > 0) {
1090         // we have contending threads
1091         ResourceMark rm;
1092         // get_pending_threads returns only java thread so we do not need to
1093         // check for  non java threads.
1094         GrowableArray<JavaThread*>* wantList = Threads::get_pending_threads(
1095           nWant, (address)mon, !at_safepoint);
1096         if (wantList->length() < nWant) {
1097           // robustness: the pending list has gotten smaller
1098           nWant = wantList->length();
1099         }
1100         for (int i = 0; i < nWant; i++) {
1101           JavaThread *pending_thread = wantList->at(i);
1102           // If the monitor has no owner, then a non-suspended contending
1103           // thread could potentially change the state of the monitor by
1104           // entering it. The JVM/TI spec doesn't allow this.
1105           if (owning_thread == NULL && !at_safepoint &
1106               !JvmtiEnv::is_thread_fully_suspended(pending_thread, true, &debug_bits)) {
1107             if (ret.owner != NULL) {
1108               destroy_jni_reference(calling_thread, ret.owner);
1109             }
1110             for (int j = 0; j < i; j++) {
1111               destroy_jni_reference(calling_thread, ret.waiters[j]);
1112             }
1113             deallocate((unsigned char*)ret.waiters);
1114             deallocate((unsigned char*)ret.notify_waiters);
1115             return JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1116           }
1117           Handle th(pending_thread->threadObj());
1118           ret.waiters[i] = (jthread)jni_reference(calling_thread, th);
1119         }
1120       }
1121       if (nWait > 0) {
1122         // we have threads in Object.wait()
1123         int offset = nWant;  // add after any contending threads
1124         ObjectWaiter *waiter = mon->first_waiter();
1125         for (int i = 0, j = 0; i < nWait; i++) {
1126           if (waiter == NULL) {
1127             // robustness: the waiting list has gotten smaller
1128             nWait = j;
1129             break;
1130           }
1131           Thread *t = mon->thread_of_waiter(waiter);
1132           if (t != NULL && t->is_Java_thread()) {
1133             JavaThread *wjava_thread = (JavaThread *)t;
1134             // If the thread was found on the ObjectWaiter list, then
1135             // it has not been notified. This thread can't change the
1136             // state of the monitor so it doesn't need to be suspended.
1137             Handle th(wjava_thread->threadObj());
1138             ret.waiters[offset + j] = (jthread)jni_reference(calling_thread, th);
1139             ret.notify_waiters[j++] = (jthread)jni_reference(calling_thread, th);
1140           }
1141           waiter = mon->next_waiter(waiter);
1142         }
1143       }
1144     }
1145 
1146     // Adjust count. nWant and nWait count values may be less than original.
1147     ret.waiter_count = nWant + nWait;
1148     ret.notify_waiter_count = nWait;
1149   } else {
1150     // this object has a lightweight monitor and we have nothing more
1151     // to do here because the defaults are just fine.
1152   }
1153 
1154   // we don't update return parameter unless everything worked
1155   *info_ptr = ret;
1156 
1157   return JVMTI_ERROR_NONE;
1158 }
1159 
1160 ResourceTracker::ResourceTracker(JvmtiEnv* env) {
1161   _env = env;
1162   _allocations = new (ResourceObj::C_HEAP) GrowableArray<unsigned char*>(20, true);
1163   _failed = false;
1164 }
1165 ResourceTracker::~ResourceTracker() {
1166   if (_failed) {
1167     for (int i=0; i<_allocations->length(); i++) {
1168       _env->deallocate(_allocations->at(i));
1169     }
1170   }
1171   delete _allocations;
1172 }
1173 
1174 jvmtiError ResourceTracker::allocate(jlong size, unsigned char** mem_ptr) {
1175   unsigned char *ptr;
1176   jvmtiError err = _env->allocate(size, &ptr);
1177   if (err == JVMTI_ERROR_NONE) {
1178     _allocations->append(ptr);
1179     *mem_ptr = ptr;
1180   } else {
1181     *mem_ptr = NULL;
1182     _failed = true;
1183   }
1184   return err;
1185  }
1186 
1187 unsigned char* ResourceTracker::allocate(jlong size) {
1188   unsigned char* ptr;
1189   allocate(size, &ptr);
1190   return ptr;
1191 }
1192 
1193 char* ResourceTracker::strdup(const char* str) {
1194   char *dup_str = (char*)allocate(strlen(str)+1);
1195   if (dup_str != NULL) {
1196     strcpy(dup_str, str);
1197   }
1198   return dup_str;
1199 }
1200 
1201 struct StackInfoNode {
1202   struct StackInfoNode *next;
1203   jvmtiStackInfo info;
1204 };
1205 
1206 // Create a jvmtiStackInfo inside a linked list node and create a
1207 // buffer for the frame information, both allocated as resource objects.
1208 // Fill in both the jvmtiStackInfo and the jvmtiFrameInfo.
1209 // Note that either or both of thr and thread_oop
1210 // may be null if the thread is new or has exited.
1211 void
1212 VM_GetMultipleStackTraces::fill_frames(jthread jt, JavaThread *thr, oop thread_oop) {
1213   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1214 
1215   jint state = 0;
1216   struct StackInfoNode *node = NEW_RESOURCE_OBJ(struct StackInfoNode);
1217   jvmtiStackInfo *infop = &(node->info);
1218   node->next = head();
1219   set_head(node);
1220   infop->frame_count = 0;
1221   infop->thread = jt;
1222 
1223   if (thread_oop != NULL) {
1224     // get most state bits
1225     state = (jint)java_lang_Thread::get_thread_status(thread_oop);
1226   }
1227 
1228   if (thr != NULL) {    // add more state bits if there is a JavaThead to query
1229     // same as is_being_ext_suspended() but without locking
1230     if (thr->is_ext_suspended() || thr->is_external_suspend()) {
1231       state |= JVMTI_THREAD_STATE_SUSPENDED;
1232     }
1233     JavaThreadState jts = thr->thread_state();
1234     if (jts == _thread_in_native) {
1235       state |= JVMTI_THREAD_STATE_IN_NATIVE;
1236     }
1237     OSThread* osThread = thr->osthread();
1238     if (osThread != NULL && osThread->interrupted()) {
1239       state |= JVMTI_THREAD_STATE_INTERRUPTED;
1240     }
1241   }
1242   infop->state = state;
1243 
1244   if (thr != NULL || (state & JVMTI_THREAD_STATE_ALIVE) != 0) {
1245     infop->frame_buffer = NEW_RESOURCE_ARRAY(jvmtiFrameInfo, max_frame_count());
1246     env()->get_stack_trace(thr, 0, max_frame_count(),
1247                            infop->frame_buffer, &(infop->frame_count));
1248   } else {
1249     infop->frame_buffer = NULL;
1250     infop->frame_count = 0;
1251   }
1252   _frame_count_total += infop->frame_count;
1253 }
1254 
1255 // Based on the stack information in the linked list, allocate memory
1256 // block to return and fill it from the info in the linked list.
1257 void
1258 VM_GetMultipleStackTraces::allocate_and_fill_stacks(jint thread_count) {
1259   // do I need to worry about alignment issues?
1260   jlong alloc_size =  thread_count       * sizeof(jvmtiStackInfo)
1261                     + _frame_count_total * sizeof(jvmtiFrameInfo);
1262   env()->allocate(alloc_size, (unsigned char **)&_stack_info);
1263 
1264   // pointers to move through the newly allocated space as it is filled in
1265   jvmtiStackInfo *si = _stack_info + thread_count;      // bottom of stack info
1266   jvmtiFrameInfo *fi = (jvmtiFrameInfo *)si;            // is the top of frame info
1267 
1268   // copy information in resource area into allocated buffer
1269   // insert stack info backwards since linked list is backwards
1270   // insert frame info forwards
1271   // walk the StackInfoNodes
1272   for (struct StackInfoNode *sin = head(); sin != NULL; sin = sin->next) {
1273     jint frame_count = sin->info.frame_count;
1274     size_t frames_size = frame_count * sizeof(jvmtiFrameInfo);
1275     --si;
1276     memcpy(si, &(sin->info), sizeof(jvmtiStackInfo));
1277     if (frames_size == 0) {
1278       si->frame_buffer = NULL;
1279     } else {
1280       memcpy(fi, sin->info.frame_buffer, frames_size);
1281       si->frame_buffer = fi;  // point to the new allocated copy of the frames
1282       fi += frame_count;
1283     }
1284   }
1285   assert(si == _stack_info, "the last copied stack info must be the first record");
1286   assert((unsigned char *)fi == ((unsigned char *)_stack_info) + alloc_size,
1287          "the last copied frame info must be the last record");
1288 }
1289 
1290 
1291 void
1292 VM_GetThreadListStackTraces::doit() {
1293   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1294 
1295   ResourceMark rm;
1296   for (int i = 0; i < _thread_count; ++i) {
1297     jthread jt = _thread_list[i];
1298     oop thread_oop = JNIHandles::resolve_external_guard(jt);
1299     if (thread_oop == NULL || !thread_oop->is_a(SystemDictionary::Thread_klass())) {
1300       set_result(JVMTI_ERROR_INVALID_THREAD);
1301       return;
1302     }
1303     fill_frames(jt, java_lang_Thread::thread(thread_oop), thread_oop);
1304   }
1305   allocate_and_fill_stacks(_thread_count);
1306 }
1307 
1308 void
1309 VM_GetAllStackTraces::doit() {
1310   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1311 
1312   ResourceMark rm;
1313   _final_thread_count = 0;
1314   for (JavaThread *jt = Threads::first(); jt != NULL; jt = jt->next()) {
1315     oop thread_oop = jt->threadObj();
1316     if (thread_oop != NULL &&
1317         !jt->is_exiting() &&
1318         java_lang_Thread::is_alive(thread_oop) &&
1319         !jt->is_hidden_from_external_view()) {
1320       ++_final_thread_count;
1321       // Handle block of the calling thread is used to create local refs.
1322       fill_frames((jthread)JNIHandles::make_local(_calling_thread, thread_oop),
1323                   jt, thread_oop);
1324     }
1325   }
1326   allocate_and_fill_stacks(_final_thread_count);
1327 }
1328 
1329 // Verifies that the top frame is a java frame in an expected state.
1330 // Deoptimizes frame if needed.
1331 // Checks that the frame method signature matches the return type (tos).
1332 // HandleMark must be defined in the caller only.
1333 // It is to keep a ret_ob_h handle alive after return to the caller.
1334 jvmtiError
1335 JvmtiEnvBase::check_top_frame(JavaThread* current_thread, JavaThread* java_thread,
1336                               jvalue value, TosState tos, Handle* ret_ob_h) {
1337   ResourceMark rm(current_thread);
1338 
1339   vframe *vf = vframeFor(java_thread, 0);
1340   NULL_CHECK(vf, JVMTI_ERROR_NO_MORE_FRAMES);
1341 
1342   javaVFrame *jvf = (javaVFrame*) vf;
1343   if (!vf->is_java_frame() || jvf->method()->is_native()) {
1344     return JVMTI_ERROR_OPAQUE_FRAME;
1345   }
1346 
1347   // If the frame is a compiled one, need to deoptimize it.
1348   if (vf->is_compiled_frame()) {
1349     if (!vf->fr().can_be_deoptimized()) {
1350       return JVMTI_ERROR_OPAQUE_FRAME;
1351     }
1352     Deoptimization::deoptimize_frame(java_thread, jvf->fr().id());
1353   }
1354 
1355   // Get information about method return type
1356   Symbol* signature = jvf->method()->signature();
1357 
1358   ResultTypeFinder rtf(signature);
1359   TosState fr_tos = as_TosState(rtf.type());
1360   if (fr_tos != tos) {
1361     if (tos != itos || (fr_tos != btos && fr_tos != ctos && fr_tos != stos)) {
1362       return JVMTI_ERROR_TYPE_MISMATCH;
1363     }
1364   }
1365 
1366   // Check that the jobject class matches the return type signature.
1367   jobject jobj = value.l;
1368   if (tos == atos && jobj != NULL) { // NULL reference is allowed
1369     Handle ob_h = Handle(current_thread, JNIHandles::resolve_external_guard(jobj));
1370     NULL_CHECK(ob_h, JVMTI_ERROR_INVALID_OBJECT);
1371     KlassHandle ob_kh = KlassHandle(current_thread, ob_h()->klass());
1372     NULL_CHECK(ob_kh, JVMTI_ERROR_INVALID_OBJECT);
1373 
1374     // Method return type signature.
1375     char* ty_sign = 1 + strchr(signature->as_C_string(), ')');
1376 
1377     if (!VM_GetOrSetLocal::is_assignable(ty_sign, Klass::cast(ob_kh()), current_thread)) {
1378       return JVMTI_ERROR_TYPE_MISMATCH;
1379     }
1380     *ret_ob_h = ob_h;
1381   }
1382   return JVMTI_ERROR_NONE;
1383 } /* end check_top_frame */
1384 
1385 
1386 // ForceEarlyReturn<type> follows the PopFrame approach in many aspects.
1387 // Main difference is on the last stage in the interpreter.
1388 // The PopFrame stops method execution to continue execution
1389 // from the same method call instruction.
1390 // The ForceEarlyReturn forces return from method so the execution
1391 // continues at the bytecode following the method call.
1392 
1393 // Threads_lock NOT held, java_thread not protected by lock
1394 // java_thread - pre-checked
1395 
1396 jvmtiError
1397 JvmtiEnvBase::force_early_return(JavaThread* java_thread, jvalue value, TosState tos) {
1398   JavaThread* current_thread = JavaThread::current();
1399   HandleMark   hm(current_thread);
1400   uint32_t debug_bits = 0;
1401 
1402   // retrieve or create the state
1403   JvmtiThreadState* state = JvmtiThreadState::state_for(java_thread);
1404   if (state == NULL) {
1405     return JVMTI_ERROR_THREAD_NOT_ALIVE;
1406   }
1407 
1408   // Check if java_thread is fully suspended
1409   if (!is_thread_fully_suspended(java_thread,
1410                                  true /* wait for suspend completion */,
1411                                  &debug_bits)) {
1412     return JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1413   }
1414 
1415   // Check to see if a ForceEarlyReturn was already in progress
1416   if (state->is_earlyret_pending()) {
1417     // Probably possible for JVMTI clients to trigger this, but the
1418     // JPDA backend shouldn't allow this to happen
1419     return JVMTI_ERROR_INTERNAL;
1420   }
1421   {
1422     // The same as for PopFrame. Workaround bug:
1423     //  4812902: popFrame hangs if the method is waiting at a synchronize
1424     // Catch this condition and return an error to avoid hanging.
1425     // Now JVMTI spec allows an implementation to bail out with an opaque
1426     // frame error.
1427     OSThread* osThread = java_thread->osthread();
1428     if (osThread->get_state() == MONITOR_WAIT) {
1429       return JVMTI_ERROR_OPAQUE_FRAME;
1430     }
1431   }
1432   Handle ret_ob_h = Handle();
1433   jvmtiError err = check_top_frame(current_thread, java_thread, value, tos, &ret_ob_h);
1434   if (err != JVMTI_ERROR_NONE) {
1435     return err;
1436   }
1437   assert(tos != atos || value.l == NULL || ret_ob_h() != NULL,
1438          "return object oop must not be NULL if jobject is not NULL");
1439 
1440   // Update the thread state to reflect that the top frame must be
1441   // forced to return.
1442   // The current frame will be returned later when the suspended
1443   // thread is resumed and right before returning from VM to Java.
1444   // (see call_VM_base() in assembler_<cpu>.cpp).
1445 
1446   state->set_earlyret_pending();
1447   state->set_earlyret_oop(ret_ob_h());
1448   state->set_earlyret_value(value, tos);
1449 
1450   // Set pending step flag for this early return.
1451   // It is cleared when next step event is posted.
1452   state->set_pending_step_for_earlyret();
1453 
1454   return JVMTI_ERROR_NONE;
1455 } /* end force_early_return */
1456 
1457 void
1458 JvmtiMonitorClosure::do_monitor(ObjectMonitor* mon) {
1459   if ( _error != JVMTI_ERROR_NONE) {
1460     // Error occurred in previous iteration so no need to add
1461     // to the list.
1462     return;
1463   }
1464   if (mon->owner() == _java_thread ) {
1465     // Filter out on stack monitors collected during stack walk.
1466     oop obj = (oop)mon->object();
1467     bool found = false;
1468     for (int j = 0; j < _owned_monitors_list->length(); j++) {
1469       jobject jobj = ((jvmtiMonitorStackDepthInfo*)_owned_monitors_list->at(j))->monitor;
1470       oop check = JNIHandles::resolve(jobj);
1471       if (check == obj) {
1472         // On stack monitor already collected during the stack walk.
1473         found = true;
1474         break;
1475       }
1476     }
1477     if (found == false) {
1478       // This is off stack monitor (e.g. acquired via jni MonitorEnter).
1479       jvmtiError err;
1480       jvmtiMonitorStackDepthInfo *jmsdi;
1481       err = _env->allocate(sizeof(jvmtiMonitorStackDepthInfo), (unsigned char **)&jmsdi);
1482       if (err != JVMTI_ERROR_NONE) {
1483         _error = err;
1484         return;
1485       }
1486       Handle hobj(obj);
1487       jmsdi->monitor = _env->jni_reference(_calling_thread, hobj);
1488       // stack depth is unknown for this monitor.
1489       jmsdi->stack_depth = -1;
1490       _owned_monitors_list->append(jmsdi);
1491     }
1492   }
1493 }
1494 
1495 #endif // !JVMTI_KERNEL