1 /*
   2  * Copyright (c) 2003, 2014, 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   // register extension functions and events
  78   JvmtiExtensions::register_extensions();
  79 
  80 #ifdef JVMTI_TRACE
  81   JvmtiTrace::initialize();
  82 #endif
  83 
  84   _globally_initialized = true;
  85 }
  86 
  87 
  88 void
  89 JvmtiEnvBase::initialize() {
  90   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
  91 
  92   // Add this environment to the end of the environment list (order is important)
  93   {
  94     // This block of code must not contain any safepoints, as list deallocation
  95     // (which occurs at a safepoint) cannot occur simultaneously with this list
  96     // addition.  Note: No_Safepoint_Verifier cannot, currently, be used before
  97     // threads exist.
  98     JvmtiEnvIterator it;
  99     JvmtiEnvBase *previous_env = NULL;
 100     for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
 101       previous_env = env;
 102     }
 103     if (previous_env == NULL) {
 104       _head_environment = this;
 105     } else {
 106       previous_env->set_next_environment(this);
 107     }
 108   }
 109 
 110   if (_globally_initialized == false) {
 111     globally_initialize();
 112   }
 113 }
 114 
 115 
 116 bool
 117 JvmtiEnvBase::is_valid() {
 118   jint value = 0;
 119 
 120   // This object might not be a JvmtiEnvBase so we can't assume
 121   // the _magic field is properly aligned. Get the value in a safe
 122   // way and then check against JVMTI_MAGIC.
 123 
 124   switch (sizeof(_magic)) {
 125   case 2:
 126     value = Bytes::get_native_u2((address)&_magic);
 127     break;
 128 
 129   case 4:
 130     value = Bytes::get_native_u4((address)&_magic);
 131     break;
 132 
 133   case 8:
 134     value = Bytes::get_native_u8((address)&_magic);
 135     break;
 136 
 137   default:
 138     guarantee(false, "_magic field is an unexpected size");
 139   }
 140 
 141   return value == JVMTI_MAGIC;
 142 }
 143 
 144 
 145 bool
 146 JvmtiEnvBase::use_version_1_0_semantics() {
 147   int major, minor, micro;
 148 
 149   JvmtiExport::decode_version_values(_version, &major, &minor, &micro);
 150   return major == 1 && minor == 0;  // micro version doesn't matter here
 151 }
 152 
 153 
 154 bool
 155 JvmtiEnvBase::use_version_1_1_semantics() {
 156   int major, minor, micro;
 157 
 158   JvmtiExport::decode_version_values(_version, &major, &minor, &micro);
 159   return major == 1 && minor == 1;  // micro version doesn't matter here
 160 }
 161 
 162 bool
 163 JvmtiEnvBase::use_version_1_2_semantics() {
 164   int major, minor, micro;
 165 
 166   JvmtiExport::decode_version_values(_version, &major, &minor, &micro);
 167   return major == 1 && minor == 2;  // micro version doesn't matter here
 168 }
 169 
 170 
 171 JvmtiEnvBase::JvmtiEnvBase(jint version) : _env_event_enable() {
 172   _version = version;
 173   _env_local_storage = NULL;
 174   _tag_map = NULL;
 175   _native_method_prefix_count = 0;
 176   _native_method_prefixes = NULL;
 177   _next = NULL;
 178   _class_file_load_hook_ever_enabled = false;
 179 
 180   // Moot since ClassFileLoadHook not yet enabled.
 181   // But "true" will give a more predictable ClassFileLoadHook behavior
 182   // for environment creation during ClassFileLoadHook.
 183   _is_retransformable = true;
 184 
 185   // all callbacks initially NULL
 186   memset(&_event_callbacks,0,sizeof(jvmtiEventCallbacks));
 187 
 188   // all capabilities initially off
 189   memset(&_current_capabilities, 0, sizeof(_current_capabilities));
 190 
 191   // all prohibited capabilities initially off
 192   memset(&_prohibited_capabilities, 0, sizeof(_prohibited_capabilities));
 193 
 194   _magic = JVMTI_MAGIC;
 195 
 196   JvmtiEventController::env_initialize((JvmtiEnv*)this);
 197 
 198 #ifdef JVMTI_TRACE
 199   _jvmti_external.functions = TraceJVMTI != NULL ? &jvmtiTrace_Interface : &jvmti_Interface;
 200 #else
 201   _jvmti_external.functions = &jvmti_Interface;
 202 #endif
 203 }
 204 
 205 
 206 void
 207 JvmtiEnvBase::dispose() {
 208 
 209 #ifdef JVMTI_TRACE
 210   JvmtiTrace::shutdown();
 211 #endif
 212 
 213   // Dispose of event info and let the event controller call us back
 214   // in a locked state (env_dispose, below)
 215   JvmtiEventController::env_dispose(this);
 216 }
 217 
 218 void
 219 JvmtiEnvBase::env_dispose() {
 220   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
 221 
 222   // We have been entered with all events disabled on this environment.
 223   // A race to re-enable events (by setting callbacks) is prevented by
 224   // checking for a valid environment when setting callbacks (while
 225   // holding the JvmtiThreadState_lock).
 226 
 227   // Mark as invalid.
 228   _magic = DISPOSED_MAGIC;
 229 
 230   // Relinquish all capabilities.
 231   jvmtiCapabilities *caps = get_capabilities();
 232   JvmtiManageCapabilities::relinquish_capabilities(caps, caps, caps);
 233 
 234   // Same situation as with events (see above)
 235   set_native_method_prefixes(0, NULL);
 236 
 237   JvmtiTagMap* tag_map_to_deallocate = _tag_map;
 238   set_tag_map(NULL);
 239   // A tag map can be big, deallocate it now
 240   if (tag_map_to_deallocate != NULL) {
 241     delete tag_map_to_deallocate;
 242   }
 243 
 244   _needs_clean_up = true;
 245 }
 246 
 247 
 248 JvmtiEnvBase::~JvmtiEnvBase() {
 249   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
 250 
 251   // There is a small window of time during which the tag map of a
 252   // disposed environment could have been reallocated.
 253   // Make sure it is gone.
 254   JvmtiTagMap* tag_map_to_deallocate = _tag_map;
 255   set_tag_map(NULL);
 256   // A tag map can be big, deallocate it now
 257   if (tag_map_to_deallocate != NULL) {
 258     delete tag_map_to_deallocate;
 259   }
 260 
 261   _magic = BAD_MAGIC;
 262 }
 263 
 264 
 265 void
 266 JvmtiEnvBase::periodic_clean_up() {
 267   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
 268 
 269   // JvmtiEnvBase reference is saved in JvmtiEnvThreadState. So
 270   // clean up JvmtiThreadState before deleting JvmtiEnv pointer.
 271   JvmtiThreadState::periodic_clean_up();
 272 
 273   // Unlink all invalid environments from the list of environments
 274   // and deallocate them
 275   JvmtiEnvIterator it;
 276   JvmtiEnvBase* previous_env = NULL;
 277   JvmtiEnvBase* env = it.first();
 278   while (env != NULL) {
 279     if (env->is_valid()) {
 280       previous_env = env;
 281       env = it.next(env);
 282     } else {
 283       // This one isn't valid, remove it from the list and deallocate it
 284       JvmtiEnvBase* defunct_env = env;
 285       env = it.next(env);
 286       if (previous_env == NULL) {
 287         _head_environment = env;
 288       } else {
 289         previous_env->set_next_environment(env);
 290       }
 291       delete defunct_env;
 292     }
 293   }
 294 
 295 }
 296 
 297 
 298 void
 299 JvmtiEnvBase::check_for_periodic_clean_up() {
 300   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
 301 
 302   class ThreadInsideIterationClosure: public ThreadClosure {
 303    private:
 304     bool _inside;
 305    public:
 306     ThreadInsideIterationClosure() : _inside(false) {};
 307 
 308     void do_thread(Thread* thread) {
 309       _inside |= thread->is_inside_jvmti_env_iteration();
 310     }
 311 
 312     bool is_inside_jvmti_env_iteration() {
 313       return _inside;
 314     }
 315   };
 316 
 317   if (_needs_clean_up) {
 318     // Check if we are currently iterating environment,
 319     // deallocation should not occur if we are
 320     ThreadInsideIterationClosure tiic;
 321     Threads::threads_do(&tiic);
 322     if (!tiic.is_inside_jvmti_env_iteration() &&
 323              !is_inside_dying_thread_env_iteration()) {
 324       _needs_clean_up = false;
 325       JvmtiEnvBase::periodic_clean_up();
 326     }
 327   }
 328 }
 329 
 330 
 331 void
 332 JvmtiEnvBase::record_first_time_class_file_load_hook_enabled() {
 333   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(),
 334          "sanity check");
 335 
 336   if (!_class_file_load_hook_ever_enabled) {
 337     _class_file_load_hook_ever_enabled = true;
 338 
 339     if (get_capabilities()->can_retransform_classes) {
 340       _is_retransformable = true;
 341     } else {
 342       _is_retransformable = false;
 343 
 344       // cannot add retransform capability after ClassFileLoadHook has been enabled
 345       get_prohibited_capabilities()->can_retransform_classes = 1;
 346     }
 347   }
 348 }
 349 
 350 
 351 void
 352 JvmtiEnvBase::record_class_file_load_hook_enabled() {
 353   if (!_class_file_load_hook_ever_enabled) {
 354     if (Threads::number_of_threads() == 0) {
 355       record_first_time_class_file_load_hook_enabled();
 356     } else {
 357       MutexLocker mu(JvmtiThreadState_lock);
 358       record_first_time_class_file_load_hook_enabled();
 359     }
 360   }
 361 }
 362 
 363 
 364 jvmtiError
 365 JvmtiEnvBase::set_native_method_prefixes(jint prefix_count, char** prefixes) {
 366   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(),
 367          "sanity check");
 368 
 369   int old_prefix_count = get_native_method_prefix_count();
 370   char **old_prefixes = get_native_method_prefixes();
 371 
 372   // allocate and install the new prefixex
 373   if (prefix_count == 0 || !is_valid()) {
 374     _native_method_prefix_count = 0;
 375     _native_method_prefixes = NULL;
 376   } else {
 377     // there are prefixes, allocate an array to hold them, and fill it
 378     char** new_prefixes = (char**)os::malloc((prefix_count) * sizeof(char*), mtInternal);
 379     if (new_prefixes == NULL) {
 380       return JVMTI_ERROR_OUT_OF_MEMORY;
 381     }
 382     for (int i = 0; i < prefix_count; i++) {
 383       char* prefix = prefixes[i];
 384       if (prefix == NULL) {
 385         for (int j = 0; j < (i-1); j++) {
 386           os::free(new_prefixes[j]);
 387         }
 388         os::free(new_prefixes);
 389         return JVMTI_ERROR_NULL_POINTER;
 390       }
 391       prefix = os::strdup(prefixes[i]);
 392       if (prefix == NULL) {
 393         for (int j = 0; j < (i-1); j++) {
 394           os::free(new_prefixes[j]);
 395         }
 396         os::free(new_prefixes);
 397         return JVMTI_ERROR_OUT_OF_MEMORY;
 398       }
 399       new_prefixes[i] = prefix;
 400     }
 401     _native_method_prefix_count = prefix_count;
 402     _native_method_prefixes = new_prefixes;
 403   }
 404 
 405   // now that we know the new prefixes have been successfully installed we can
 406   // safely remove the old ones
 407   if (old_prefix_count != 0) {
 408     for (int i = 0; i < old_prefix_count; i++) {
 409       os::free(old_prefixes[i]);
 410     }
 411     os::free(old_prefixes);
 412   }
 413 
 414   return JVMTI_ERROR_NONE;
 415 }
 416 
 417 
 418 // Collect all the prefixes which have been set in any JVM TI environments
 419 // by the SetNativeMethodPrefix(es) functions.  Be sure to maintain the
 420 // order of environments and the order of prefixes within each environment.
 421 // Return in a resource allocated array.
 422 char**
 423 JvmtiEnvBase::get_all_native_method_prefixes(int* count_ptr) {
 424   assert(Threads::number_of_threads() == 0 ||
 425          SafepointSynchronize::is_at_safepoint() ||
 426          JvmtiThreadState_lock->is_locked(),
 427          "sanity check");
 428 
 429   int total_count = 0;
 430   GrowableArray<char*>* prefix_array =new GrowableArray<char*>(5);
 431 
 432   JvmtiEnvIterator it;
 433   for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
 434     int prefix_count = env->get_native_method_prefix_count();
 435     char** prefixes = env->get_native_method_prefixes();
 436     for (int j = 0; j < prefix_count; j++) {
 437       // retrieve a prefix and so that it is safe against asynchronous changes
 438       // copy it into the resource area
 439       char* prefix = prefixes[j];
 440       char* prefix_copy = NEW_RESOURCE_ARRAY(char, strlen(prefix)+1);
 441       strcpy(prefix_copy, prefix);
 442       prefix_array->at_put_grow(total_count++, prefix_copy);
 443     }
 444   }
 445 
 446   char** all_prefixes = NEW_RESOURCE_ARRAY(char*, total_count);
 447   char** p = all_prefixes;
 448   for (int i = 0; i < total_count; ++i) {
 449     *p++ = prefix_array->at(i);
 450   }
 451   *count_ptr = total_count;
 452   return all_prefixes;
 453 }
 454 
 455 void
 456 JvmtiEnvBase::set_event_callbacks(const jvmtiEventCallbacks* callbacks,
 457                                                jint size_of_callbacks) {
 458   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
 459 
 460   size_t byte_cnt = sizeof(jvmtiEventCallbacks);
 461 
 462   // clear in either case to be sure we got any gap between sizes
 463   memset(&_event_callbacks, 0, byte_cnt);
 464 
 465   // Now that JvmtiThreadState_lock is held, prevent a possible race condition where events
 466   // are re-enabled by a call to set event callbacks where the DisposeEnvironment
 467   // occurs after the boiler-plate environment check and before the lock is acquired.
 468   if (callbacks != NULL && is_valid()) {
 469     if (size_of_callbacks < (jint)byte_cnt) {
 470       byte_cnt = size_of_callbacks;
 471     }
 472     memcpy(&_event_callbacks, callbacks, byte_cnt);
 473   }
 474 }
 475 
 476 // Called from JVMTI entry points which perform stack walking. If the
 477 // associated JavaThread is the current thread, then wait_for_suspend
 478 // is not used. Otherwise, it determines if we should wait for the
 479 // "other" thread to complete external suspension. (NOTE: in future
 480 // releases the suspension mechanism should be reimplemented so this
 481 // is not necessary.)
 482 //
 483 bool
 484 JvmtiEnvBase::is_thread_fully_suspended(JavaThread* thr, bool wait_for_suspend, uint32_t *bits) {
 485   // "other" threads require special handling
 486   if (thr != JavaThread::current()) {
 487     if (wait_for_suspend) {
 488       // We are allowed to wait for the external suspend to complete
 489       // so give the other thread a chance to get suspended.
 490       if (!thr->wait_for_ext_suspend_completion(SuspendRetryCount,
 491           SuspendRetryDelay, bits)) {
 492         // didn't make it so let the caller know
 493         return false;
 494       }
 495     }
 496     // We aren't allowed to wait for the external suspend to complete
 497     // so if the other thread isn't externally suspended we need to
 498     // let the caller know.
 499     else if (!thr->is_ext_suspend_completed_with_lock(bits)) {
 500       return false;
 501     }
 502   }
 503 
 504   return true;
 505 }
 506 
 507 
 508 // In the fullness of time, all users of the method should instead
 509 // directly use allocate, besides being cleaner and faster, this will
 510 // mean much better out of memory handling
 511 unsigned char *
 512 JvmtiEnvBase::jvmtiMalloc(jlong size) {
 513   unsigned char* mem;
 514   jvmtiError result = allocate(size, &mem);
 515   assert(result == JVMTI_ERROR_NONE, "Allocate failed");
 516   return mem;
 517 }
 518 
 519 
 520 //
 521 // Threads
 522 //
 523 
 524 jobject *
 525 JvmtiEnvBase::new_jobjectArray(int length, Handle *handles) {
 526   if (length == 0) {
 527     return NULL;
 528   }
 529 
 530   jobject *objArray = (jobject *) jvmtiMalloc(sizeof(jobject) * length);
 531   NULL_CHECK(objArray, NULL);
 532 
 533   for (int i=0; i<length; i++) {
 534     objArray[i] = jni_reference(handles[i]);
 535   }
 536   return objArray;
 537 }
 538 
 539 jthread *
 540 JvmtiEnvBase::new_jthreadArray(int length, Handle *handles) {
 541   return (jthread *) new_jobjectArray(length,handles);
 542 }
 543 
 544 jthreadGroup *
 545 JvmtiEnvBase::new_jthreadGroupArray(int length, Handle *handles) {
 546   return (jthreadGroup *) new_jobjectArray(length,handles);
 547 }
 548 
 549 
 550 JavaThread *
 551 JvmtiEnvBase::get_JavaThread(jthread jni_thread) {
 552   oop t = JNIHandles::resolve_external_guard(jni_thread);
 553   if (t == NULL || !t->is_a(SystemDictionary::Thread_klass())) {
 554     return NULL;
 555   }
 556   // The following returns NULL if the thread has not yet run or is in
 557   // process of exiting
 558   return java_lang_Thread::thread(t);
 559 }
 560 
 561 
 562 // return the vframe on the specified thread and depth, NULL if no such frame
 563 vframe*
 564 JvmtiEnvBase::vframeFor(JavaThread* java_thread, jint depth) {
 565   if (!java_thread->has_last_Java_frame()) {
 566     return NULL;
 567   }
 568   RegisterMap reg_map(java_thread);
 569   vframe *vf = java_thread->last_java_vframe(&reg_map);
 570   int d = 0;
 571   while ((vf != NULL) && (d < depth)) {
 572     vf = vf->java_sender();
 573     d++;
 574   }
 575   return vf;
 576 }
 577 
 578 
 579 //
 580 // utilities: JNI objects
 581 //
 582 
 583 
 584 jclass
 585 JvmtiEnvBase::get_jni_class_non_null(Klass* k) {
 586   assert(k != NULL, "k != NULL");
 587   return (jclass)jni_reference(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   ResourceMark rm;
 629   HandleMark   hm;
 630   RegisterMap  reg_map(java_thread);
 631 
 632   for(javaVFrame *jvf=java_thread->last_java_vframe(&reg_map); jvf != NULL;
 633                                                  jvf = jvf->java_sender()) {
 634     GrowableArray<MonitorInfo*>* mons = jvf->monitors();
 635     if (!mons->is_empty()) {
 636       for (int i = 0; i < mons->length(); i++) {
 637         MonitorInfo *mi = mons->at(i);
 638         if (mi->owner_is_scalar_replaced()) continue;
 639 
 640         // see if owner of the monitor is our object
 641         if (mi->owner() != NULL && mi->owner() == hobj()) {
 642           ret++;
 643         }
 644       }
 645     }
 646   }
 647   return ret;
 648 }
 649 
 650 
 651 
 652 jvmtiError
 653 JvmtiEnvBase::get_current_contended_monitor(JavaThread *calling_thread, JavaThread *java_thread, jobject *monitor_ptr) {
 654 #ifdef ASSERT
 655   uint32_t debug_bits = 0;
 656 #endif
 657   assert((SafepointSynchronize::is_at_safepoint() ||
 658           is_thread_fully_suspended(java_thread, false, &debug_bits)),
 659          "at safepoint or target thread is suspended");
 660   oop obj = NULL;
 661   ObjectMonitor *mon = java_thread->current_waiting_monitor();
 662   if (mon == NULL) {
 663     // thread is not doing an Object.wait() call
 664     mon = java_thread->current_pending_monitor();
 665     if (mon != NULL) {
 666       // The thread is trying to enter() or raw_enter() an ObjectMonitor.
 667       obj = (oop)mon->object();
 668       // If obj == NULL, then ObjectMonitor is raw which doesn't count
 669       // as contended for this API
 670     }
 671     // implied else: no contended ObjectMonitor
 672   } else {
 673     // thread is doing an Object.wait() call
 674     obj = (oop)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;
 682     Handle     hobj(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   jvmtiError err = JVMTI_ERROR_NONE;
 693 #ifdef ASSERT
 694   uint32_t debug_bits = 0;
 695 #endif
 696   assert((SafepointSynchronize::is_at_safepoint() ||
 697           is_thread_fully_suspended(java_thread, false, &debug_bits)),
 698          "at safepoint or target thread is suspended");
 699 
 700   if (java_thread->has_last_Java_frame()) {
 701     ResourceMark rm;
 702     HandleMark   hm;
 703     RegisterMap  reg_map(java_thread);
 704 
 705     int depth = 0;
 706     for (javaVFrame *jvf = java_thread->last_java_vframe(&reg_map); jvf != NULL;
 707          jvf = jvf->java_sender()) {
 708       if (depth++ < MaxJavaStackTraceDepth) {  // check for stack too deep
 709         // add locked objects for this frame into list
 710         err = get_locked_objects_in_frame(calling_thread, java_thread, jvf, owned_monitors_list, depth-1);
 711         if (err != JVMTI_ERROR_NONE) {
 712           return err;
 713         }
 714       }
 715     }
 716   }
 717 
 718   // Get off stack monitors. (e.g. acquired via jni MonitorEnter).
 719   JvmtiMonitorClosure jmc(java_thread, calling_thread, owned_monitors_list, this);
 720   ObjectSynchronizer::monitors_iterate(&jmc);
 721   err = jmc.error();
 722 
 723   return err;
 724 }
 725 
 726 // Save JNI local handles for any objects that this frame owns.
 727 jvmtiError
 728 JvmtiEnvBase::get_locked_objects_in_frame(JavaThread* calling_thread, JavaThread* java_thread,
 729                                  javaVFrame *jvf, GrowableArray<jvmtiMonitorStackDepthInfo*>* owned_monitors_list, int stack_depth) {
 730   jvmtiError err = JVMTI_ERROR_NONE;
 731   ResourceMark rm;
 732 
 733   GrowableArray<MonitorInfo*>* mons = jvf->monitors();
 734   if (mons->is_empty()) {
 735     return err;  // this javaVFrame holds no monitors
 736   }
 737 
 738   HandleMark hm;
 739   oop wait_obj = NULL;
 740   {
 741     // save object of current wait() call (if any) for later comparison
 742     ObjectMonitor *mon = java_thread->current_waiting_monitor();
 743     if (mon != NULL) {
 744       wait_obj = (oop)mon->object();
 745     }
 746   }
 747   oop pending_obj = NULL;
 748   {
 749     // save object of current enter() call (if any) for later comparison
 750     ObjectMonitor *mon = java_thread->current_pending_monitor();
 751     if (mon != NULL) {
 752       pending_obj = (oop)mon->object();
 753     }
 754   }
 755 
 756   for (int i = 0; i < mons->length(); i++) {
 757     MonitorInfo *mi = mons->at(i);
 758 
 759     if (mi->owner_is_scalar_replaced()) continue;
 760 
 761     oop obj = mi->owner();
 762     if (obj == NULL) {
 763       // this monitor doesn't have an owning object so skip it
 764       continue;
 765     }
 766 
 767     if (wait_obj == obj) {
 768       // the thread is waiting on this monitor so it isn't really owned
 769       continue;
 770     }
 771 
 772     if (pending_obj == obj) {
 773       // the thread is pending on this monitor so it isn't really owned
 774       continue;
 775     }
 776 
 777     if (owned_monitors_list->length() > 0) {
 778       // Our list has at least one object on it so we have to check
 779       // for recursive object locking
 780       bool found = false;
 781       for (int j = 0; j < owned_monitors_list->length(); j++) {
 782         jobject jobj = ((jvmtiMonitorStackDepthInfo*)owned_monitors_list->at(j))->monitor;
 783         oop check = JNIHandles::resolve(jobj);
 784         if (check == obj) {
 785           found = true;  // we found the object
 786           break;
 787         }
 788       }
 789 
 790       if (found) {
 791         // already have this object so don't include it
 792         continue;
 793       }
 794     }
 795 
 796     // add the owning object to our list
 797     jvmtiMonitorStackDepthInfo *jmsdi;
 798     err = allocate(sizeof(jvmtiMonitorStackDepthInfo), (unsigned char **)&jmsdi);
 799     if (err != JVMTI_ERROR_NONE) {
 800         return err;
 801     }
 802     Handle hobj(obj);
 803     jmsdi->monitor = jni_reference(calling_thread, hobj);
 804     jmsdi->stack_depth = stack_depth;
 805     owned_monitors_list->append(jmsdi);
 806   }
 807 
 808   return err;
 809 }
 810 
 811 jvmtiError
 812 JvmtiEnvBase::get_stack_trace(JavaThread *java_thread,
 813                               jint start_depth, jint max_count,
 814                               jvmtiFrameInfo* frame_buffer, jint* count_ptr) {
 815 #ifdef ASSERT
 816   uint32_t debug_bits = 0;
 817 #endif
 818   assert((SafepointSynchronize::is_at_safepoint() ||
 819           is_thread_fully_suspended(java_thread, false, &debug_bits)),
 820          "at safepoint or target thread is suspended");
 821   int count = 0;
 822   if (java_thread->has_last_Java_frame()) {
 823     RegisterMap reg_map(java_thread);
 824     Thread* current_thread = Thread::current();
 825     ResourceMark rm(current_thread);
 826     javaVFrame *jvf = java_thread->last_java_vframe(&reg_map);
 827     HandleMark hm(current_thread);
 828     if (start_depth != 0) {
 829       if (start_depth > 0) {
 830         for (int j = 0; j < start_depth && jvf != NULL; j++) {
 831           jvf = jvf->java_sender();
 832         }
 833         if (jvf == NULL) {
 834           // start_depth is deeper than the stack depth
 835           return JVMTI_ERROR_ILLEGAL_ARGUMENT;
 836         }
 837       } else { // start_depth < 0
 838         // we are referencing the starting depth based on the oldest
 839         // part of the stack.
 840         // optimize to limit the number of times that java_sender() is called
 841         javaVFrame *jvf_cursor = jvf;
 842         javaVFrame *jvf_prev = NULL;
 843         javaVFrame *jvf_prev_prev;
 844         int j = 0;
 845         while (jvf_cursor != NULL) {
 846           jvf_prev_prev = jvf_prev;
 847           jvf_prev = jvf_cursor;
 848           for (j = 0; j > start_depth && jvf_cursor != NULL; j--) {
 849             jvf_cursor = jvf_cursor->java_sender();
 850           }
 851         }
 852         if (j == start_depth) {
 853           // previous pointer is exactly where we want to start
 854           jvf = jvf_prev;
 855         } else {
 856           // we need to back up further to get to the right place
 857           if (jvf_prev_prev == NULL) {
 858             // the -start_depth is greater than the stack depth
 859             return JVMTI_ERROR_ILLEGAL_ARGUMENT;
 860           }
 861           // j now is the number of frames on the stack starting with
 862           // jvf_prev, we start from jvf_prev_prev and move older on
 863           // the stack that many, the result is -start_depth frames
 864           // remaining.
 865           jvf = jvf_prev_prev;
 866           for (; j < 0; j++) {
 867             jvf = jvf->java_sender();
 868           }
 869         }
 870       }
 871     }
 872     for (; count < max_count && jvf != NULL; count++) {
 873       frame_buffer[count].method = jvf->method()->jmethod_id();
 874       frame_buffer[count].location = (jvf->method()->is_native() ? -1 : jvf->bci());
 875       jvf = jvf->java_sender();
 876     }
 877   } else {
 878     if (start_depth != 0) {
 879       // no frames and there is a starting depth
 880       return JVMTI_ERROR_ILLEGAL_ARGUMENT;
 881     }
 882   }
 883   *count_ptr = count;
 884   return JVMTI_ERROR_NONE;
 885 }
 886 
 887 jvmtiError
 888 JvmtiEnvBase::get_frame_count(JvmtiThreadState *state, jint *count_ptr) {
 889   assert((state != NULL),
 890          "JavaThread should create JvmtiThreadState before calling this method");
 891   *count_ptr = state->count_frames();
 892   return JVMTI_ERROR_NONE;
 893 }
 894 
 895 jvmtiError
 896 JvmtiEnvBase::get_frame_location(JavaThread *java_thread, jint depth,
 897                                  jmethodID* method_ptr, jlocation* location_ptr) {
 898 #ifdef ASSERT
 899   uint32_t debug_bits = 0;
 900 #endif
 901   assert((SafepointSynchronize::is_at_safepoint() ||
 902           is_thread_fully_suspended(java_thread, false, &debug_bits)),
 903          "at safepoint or target thread is suspended");
 904   Thread* current_thread = Thread::current();
 905   ResourceMark rm(current_thread);
 906 
 907   vframe *vf = vframeFor(java_thread, depth);
 908   if (vf == NULL) {
 909     return JVMTI_ERROR_NO_MORE_FRAMES;
 910   }
 911 
 912   // vframeFor should return a java frame. If it doesn't
 913   // it means we've got an internal error and we return the
 914   // error in product mode. In debug mode we will instead
 915   // attempt to cast the vframe to a javaVFrame and will
 916   // cause an assertion/crash to allow further diagnosis.
 917 #ifdef PRODUCT
 918   if (!vf->is_java_frame()) {
 919     return JVMTI_ERROR_INTERNAL;
 920   }
 921 #endif
 922 
 923   HandleMark hm(current_thread);
 924   javaVFrame *jvf = javaVFrame::cast(vf);
 925   Method* method = jvf->method();
 926   if (method->is_native()) {
 927     *location_ptr = -1;
 928   } else {
 929     *location_ptr = jvf->bci();
 930   }
 931   *method_ptr = method->jmethod_id();
 932 
 933   return JVMTI_ERROR_NONE;
 934 }
 935 
 936 
 937 jvmtiError
 938 JvmtiEnvBase::get_object_monitor_usage(JavaThread* calling_thread, jobject object, jvmtiMonitorUsage* info_ptr) {
 939   HandleMark hm;
 940   Handle hobj;
 941 
 942   bool at_safepoint = SafepointSynchronize::is_at_safepoint();
 943 
 944   // Check arguments
 945   {
 946     oop mirror = JNIHandles::resolve_external_guard(object);
 947     NULL_CHECK(mirror, JVMTI_ERROR_INVALID_OBJECT);
 948     NULL_CHECK(info_ptr, JVMTI_ERROR_NULL_POINTER);
 949 
 950     hobj = Handle(mirror);
 951   }
 952 
 953   JavaThread *owning_thread = NULL;
 954   ObjectMonitor *mon = NULL;
 955   jvmtiMonitorUsage ret = {
 956       NULL, 0, 0, NULL, 0, NULL
 957   };
 958 
 959   uint32_t debug_bits = 0;
 960   // first derive the object's owner and entry_count (if any)
 961   {
 962     // Revoke any biases before querying the mark word
 963     if (SafepointSynchronize::is_at_safepoint()) {
 964       BiasedLocking::revoke_at_safepoint(hobj);
 965     } else {
 966       BiasedLocking::revoke_and_rebias(hobj, false, calling_thread);
 967     }
 968 
 969     address owner = NULL;
 970     {
 971       markOop mark = hobj()->mark();
 972 
 973       if (!mark->has_monitor()) {
 974         // this object has a lightweight monitor
 975 
 976         if (mark->has_locker()) {
 977           owner = (address)mark->locker(); // save the address of the Lock word
 978         }
 979         // implied else: no owner
 980       } else {
 981         // this object has a heavyweight monitor
 982         mon = mark->monitor();
 983 
 984         // The owner field of a heavyweight monitor may be NULL for no
 985         // owner, a JavaThread * or it may still be the address of the
 986         // Lock word in a JavaThread's stack. A monitor can be inflated
 987         // by a non-owning JavaThread, but only the owning JavaThread
 988         // can change the owner field from the Lock word to the
 989         // JavaThread * and it may not have done that yet.
 990         owner = (address)mon->owner();
 991       }
 992     }
 993 
 994     if (owner != NULL) {
 995       // This monitor is owned so we have to find the owning JavaThread.
 996       // Since owning_thread_from_monitor_owner() grabs a lock, GC can
 997       // move our object at this point. However, our owner value is safe
 998       // since it is either the Lock word on a stack or a JavaThread *.
 999       owning_thread = Threads::owning_thread_from_monitor_owner(owner, !at_safepoint);
1000       // Cannot assume (owning_thread != NULL) here because this function
1001       // may not have been called at a safepoint and the owning_thread
1002       // might not be suspended.
1003       if (owning_thread != NULL) {
1004         // The monitor's owner either has to be the current thread, at safepoint
1005         // or it has to be suspended. Any of these conditions will prevent both
1006         // contending and waiting threads from modifying the state of
1007         // the monitor.
1008         if (!at_safepoint && !JvmtiEnv::is_thread_fully_suspended(owning_thread, true, &debug_bits)) {
1009           // Don't worry! This return of JVMTI_ERROR_THREAD_NOT_SUSPENDED
1010           // will not make it back to the JVM/TI agent. The error code will
1011           // get intercepted in JvmtiEnv::GetObjectMonitorUsage() which
1012           // will retry the call via a VM_GetObjectMonitorUsage VM op.
1013           return JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1014         }
1015         HandleMark hm;
1016         Handle     th(owning_thread->threadObj());
1017         ret.owner = (jthread)jni_reference(calling_thread, th);
1018       }
1019       // implied else: no owner
1020     }
1021 
1022     if (owning_thread != NULL) {  // monitor is owned
1023       // The recursions field of a monitor does not reflect recursions
1024       // as lightweight locks before inflating the monitor are not included.
1025       // We have to count the number of recursive monitor entries the hard way.
1026       // We pass a handle to survive any GCs along the way.
1027       ResourceMark rm;
1028       ret.entry_count = count_locked_objects(owning_thread, hobj);
1029     }
1030     // implied else: entry_count == 0
1031   }
1032 
1033   int nWant,nWait;
1034   if (mon != NULL) {
1035     // this object has a heavyweight monitor
1036     nWant = mon->contentions(); // # of threads contending for monitor
1037     nWait = mon->waiters();     // # of threads in Object.wait()
1038     ret.waiter_count = nWant + nWait;
1039     ret.notify_waiter_count = nWait;
1040   } else {
1041     // this object has a lightweight monitor
1042     ret.waiter_count = 0;
1043     ret.notify_waiter_count = 0;
1044   }
1045 
1046   // Allocate memory for heavyweight and lightweight monitor.
1047   jvmtiError err;
1048   err = allocate(ret.waiter_count * sizeof(jthread *), (unsigned char**)&ret.waiters);
1049   if (err != JVMTI_ERROR_NONE) {
1050     return err;
1051   }
1052   err = allocate(ret.notify_waiter_count * sizeof(jthread *),
1053                  (unsigned char**)&ret.notify_waiters);
1054   if (err != JVMTI_ERROR_NONE) {
1055     deallocate((unsigned char*)ret.waiters);
1056     return err;
1057   }
1058 
1059   // now derive the rest of the fields
1060   if (mon != NULL) {
1061     // this object has a heavyweight monitor
1062 
1063     // Number of waiters may actually be less than the waiter count.
1064     // So NULL out memory so that unused memory will be NULL.
1065     memset(ret.waiters, 0, ret.waiter_count * sizeof(jthread *));
1066     memset(ret.notify_waiters, 0, ret.notify_waiter_count * sizeof(jthread *));
1067 
1068     if (ret.waiter_count > 0) {
1069       // we have contending and/or waiting threads
1070       HandleMark hm;
1071       if (nWant > 0) {
1072         // we have contending threads
1073         ResourceMark rm;
1074         // get_pending_threads returns only java thread so we do not need to
1075         // check for  non java threads.
1076         GrowableArray<JavaThread*>* wantList = Threads::get_pending_threads(
1077           nWant, (address)mon, !at_safepoint);
1078         if (wantList->length() < nWant) {
1079           // robustness: the pending list has gotten smaller
1080           nWant = wantList->length();
1081         }
1082         for (int i = 0; i < nWant; i++) {
1083           JavaThread *pending_thread = wantList->at(i);
1084           // If the monitor has no owner, then a non-suspended contending
1085           // thread could potentially change the state of the monitor by
1086           // entering it. The JVM/TI spec doesn't allow this.
1087           if (owning_thread == NULL && !at_safepoint &
1088               !JvmtiEnv::is_thread_fully_suspended(pending_thread, true, &debug_bits)) {
1089             if (ret.owner != NULL) {
1090               destroy_jni_reference(calling_thread, ret.owner);
1091             }
1092             for (int j = 0; j < i; j++) {
1093               destroy_jni_reference(calling_thread, ret.waiters[j]);
1094             }
1095             deallocate((unsigned char*)ret.waiters);
1096             deallocate((unsigned char*)ret.notify_waiters);
1097             return JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1098           }
1099           Handle th(pending_thread->threadObj());
1100           ret.waiters[i] = (jthread)jni_reference(calling_thread, th);
1101         }
1102       }
1103       if (nWait > 0) {
1104         // we have threads in Object.wait()
1105         int offset = nWant;  // add after any contending threads
1106         ObjectWaiter *waiter = mon->first_waiter();
1107         for (int i = 0, j = 0; i < nWait; i++) {
1108           if (waiter == NULL) {
1109             // robustness: the waiting list has gotten smaller
1110             nWait = j;
1111             break;
1112           }
1113           Thread *t = mon->thread_of_waiter(waiter);
1114           if (t != NULL && t->is_Java_thread()) {
1115             JavaThread *wjava_thread = (JavaThread *)t;
1116             // If the thread was found on the ObjectWaiter list, then
1117             // it has not been notified. This thread can't change the
1118             // state of the monitor so it doesn't need to be suspended.
1119             Handle th(wjava_thread->threadObj());
1120             ret.waiters[offset + j] = (jthread)jni_reference(calling_thread, th);
1121             ret.notify_waiters[j++] = (jthread)jni_reference(calling_thread, th);
1122           }
1123           waiter = mon->next_waiter(waiter);
1124         }
1125       }
1126     }
1127 
1128     // Adjust count. nWant and nWait count values may be less than original.
1129     ret.waiter_count = nWant + nWait;
1130     ret.notify_waiter_count = nWait;
1131   } else {
1132     // this object has a lightweight monitor and we have nothing more
1133     // to do here because the defaults are just fine.
1134   }
1135 
1136   // we don't update return parameter unless everything worked
1137   *info_ptr = ret;
1138 
1139   return JVMTI_ERROR_NONE;
1140 }
1141 
1142 ResourceTracker::ResourceTracker(JvmtiEnv* env) {
1143   _env = env;
1144   _allocations = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<unsigned char*>(20, true);
1145   _failed = false;
1146 }
1147 ResourceTracker::~ResourceTracker() {
1148   if (_failed) {
1149     for (int i=0; i<_allocations->length(); i++) {
1150       _env->deallocate(_allocations->at(i));
1151     }
1152   }
1153   delete _allocations;
1154 }
1155 
1156 jvmtiError ResourceTracker::allocate(jlong size, unsigned char** mem_ptr) {
1157   unsigned char *ptr;
1158   jvmtiError err = _env->allocate(size, &ptr);
1159   if (err == JVMTI_ERROR_NONE) {
1160     _allocations->append(ptr);
1161     *mem_ptr = ptr;
1162   } else {
1163     *mem_ptr = NULL;
1164     _failed = true;
1165   }
1166   return err;
1167  }
1168 
1169 unsigned char* ResourceTracker::allocate(jlong size) {
1170   unsigned char* ptr;
1171   allocate(size, &ptr);
1172   return ptr;
1173 }
1174 
1175 char* ResourceTracker::strdup(const char* str) {
1176   char *dup_str = (char*)allocate(strlen(str)+1);
1177   if (dup_str != NULL) {
1178     strcpy(dup_str, str);
1179   }
1180   return dup_str;
1181 }
1182 
1183 struct StackInfoNode {
1184   struct StackInfoNode *next;
1185   jvmtiStackInfo info;
1186 };
1187 
1188 // Create a jvmtiStackInfo inside a linked list node and create a
1189 // buffer for the frame information, both allocated as resource objects.
1190 // Fill in both the jvmtiStackInfo and the jvmtiFrameInfo.
1191 // Note that either or both of thr and thread_oop
1192 // may be null if the thread is new or has exited.
1193 void
1194 VM_GetMultipleStackTraces::fill_frames(jthread jt, JavaThread *thr, oop thread_oop) {
1195   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1196 
1197   jint state = 0;
1198   struct StackInfoNode *node = NEW_RESOURCE_OBJ(struct StackInfoNode);
1199   jvmtiStackInfo *infop = &(node->info);
1200   node->next = head();
1201   set_head(node);
1202   infop->frame_count = 0;
1203   infop->thread = jt;
1204 
1205   if (thread_oop != NULL) {
1206     // get most state bits
1207     state = (jint)java_lang_Thread::get_thread_status(thread_oop);
1208   }
1209 
1210   if (thr != NULL) {    // add more state bits if there is a JavaThead to query
1211     // same as is_being_ext_suspended() but without locking
1212     if (thr->is_ext_suspended() || thr->is_external_suspend()) {
1213       state |= JVMTI_THREAD_STATE_SUSPENDED;
1214     }
1215     JavaThreadState jts = thr->thread_state();
1216     if (jts == _thread_in_native) {
1217       state |= JVMTI_THREAD_STATE_IN_NATIVE;
1218     }
1219     OSThread* osThread = thr->osthread();
1220     if (osThread != NULL && osThread->interrupted()) {
1221       state |= JVMTI_THREAD_STATE_INTERRUPTED;
1222     }
1223   }
1224   infop->state = state;
1225 
1226   if (thr != NULL || (state & JVMTI_THREAD_STATE_ALIVE) != 0) {
1227     infop->frame_buffer = NEW_RESOURCE_ARRAY(jvmtiFrameInfo, max_frame_count());
1228     env()->get_stack_trace(thr, 0, max_frame_count(),
1229                            infop->frame_buffer, &(infop->frame_count));
1230   } else {
1231     infop->frame_buffer = NULL;
1232     infop->frame_count = 0;
1233   }
1234   _frame_count_total += infop->frame_count;
1235 }
1236 
1237 // Based on the stack information in the linked list, allocate memory
1238 // block to return and fill it from the info in the linked list.
1239 void
1240 VM_GetMultipleStackTraces::allocate_and_fill_stacks(jint thread_count) {
1241   // do I need to worry about alignment issues?
1242   jlong alloc_size =  thread_count       * sizeof(jvmtiStackInfo)
1243                     + _frame_count_total * sizeof(jvmtiFrameInfo);
1244   env()->allocate(alloc_size, (unsigned char **)&_stack_info);
1245 
1246   // pointers to move through the newly allocated space as it is filled in
1247   jvmtiStackInfo *si = _stack_info + thread_count;      // bottom of stack info
1248   jvmtiFrameInfo *fi = (jvmtiFrameInfo *)si;            // is the top of frame info
1249 
1250   // copy information in resource area into allocated buffer
1251   // insert stack info backwards since linked list is backwards
1252   // insert frame info forwards
1253   // walk the StackInfoNodes
1254   for (struct StackInfoNode *sin = head(); sin != NULL; sin = sin->next) {
1255     jint frame_count = sin->info.frame_count;
1256     size_t frames_size = frame_count * sizeof(jvmtiFrameInfo);
1257     --si;
1258     memcpy(si, &(sin->info), sizeof(jvmtiStackInfo));
1259     if (frames_size == 0) {
1260       si->frame_buffer = NULL;
1261     } else {
1262       memcpy(fi, sin->info.frame_buffer, frames_size);
1263       si->frame_buffer = fi;  // point to the new allocated copy of the frames
1264       fi += frame_count;
1265     }
1266   }
1267   assert(si == _stack_info, "the last copied stack info must be the first record");
1268   assert((unsigned char *)fi == ((unsigned char *)_stack_info) + alloc_size,
1269          "the last copied frame info must be the last record");
1270 }
1271 
1272 
1273 void
1274 VM_GetThreadListStackTraces::doit() {
1275   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1276 
1277   ResourceMark rm;
1278   for (int i = 0; i < _thread_count; ++i) {
1279     jthread jt = _thread_list[i];
1280     oop thread_oop = JNIHandles::resolve_external_guard(jt);
1281     if (thread_oop == NULL || !thread_oop->is_a(SystemDictionary::Thread_klass())) {
1282       set_result(JVMTI_ERROR_INVALID_THREAD);
1283       return;
1284     }
1285     fill_frames(jt, java_lang_Thread::thread(thread_oop), thread_oop);
1286   }
1287   allocate_and_fill_stacks(_thread_count);
1288 }
1289 
1290 void
1291 VM_GetAllStackTraces::doit() {
1292   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1293 
1294   ResourceMark rm;
1295   _final_thread_count = 0;
1296   for (JavaThread *jt = Threads::first(); jt != NULL; jt = jt->next()) {
1297     oop thread_oop = jt->threadObj();
1298     if (thread_oop != NULL &&
1299         !jt->is_exiting() &&
1300         java_lang_Thread::is_alive(thread_oop) &&
1301         !jt->is_hidden_from_external_view()) {
1302       ++_final_thread_count;
1303       // Handle block of the calling thread is used to create local refs.
1304       fill_frames((jthread)JNIHandles::make_local(_calling_thread, thread_oop),
1305                   jt, thread_oop);
1306     }
1307   }
1308   allocate_and_fill_stacks(_final_thread_count);
1309 }
1310 
1311 // Verifies that the top frame is a java frame in an expected state.
1312 // Deoptimizes frame if needed.
1313 // Checks that the frame method signature matches the return type (tos).
1314 // HandleMark must be defined in the caller only.
1315 // It is to keep a ret_ob_h handle alive after return to the caller.
1316 jvmtiError
1317 JvmtiEnvBase::check_top_frame(JavaThread* current_thread, JavaThread* java_thread,
1318                               jvalue value, TosState tos, Handle* ret_ob_h) {
1319   ResourceMark rm(current_thread);
1320 
1321   vframe *vf = vframeFor(java_thread, 0);
1322   NULL_CHECK(vf, JVMTI_ERROR_NO_MORE_FRAMES);
1323 
1324   javaVFrame *jvf = (javaVFrame*) vf;
1325   if (!vf->is_java_frame() || jvf->method()->is_native()) {
1326     return JVMTI_ERROR_OPAQUE_FRAME;
1327   }
1328 
1329   // If the frame is a compiled one, need to deoptimize it.
1330   if (vf->is_compiled_frame()) {
1331     if (!vf->fr().can_be_deoptimized()) {
1332       return JVMTI_ERROR_OPAQUE_FRAME;
1333     }
1334     Deoptimization::deoptimize_frame(java_thread, jvf->fr().id());
1335   }
1336 
1337   // Get information about method return type
1338   Symbol* signature = jvf->method()->signature();
1339 
1340   ResultTypeFinder rtf(signature);
1341   TosState fr_tos = as_TosState(rtf.type());
1342   if (fr_tos != tos) {
1343     if (tos != itos || (fr_tos != btos && fr_tos != ctos && fr_tos != stos)) {
1344       return JVMTI_ERROR_TYPE_MISMATCH;
1345     }
1346   }
1347 
1348   // Check that the jobject class matches the return type signature.
1349   jobject jobj = value.l;
1350   if (tos == atos && jobj != NULL) { // NULL reference is allowed
1351     Handle ob_h = Handle(current_thread, JNIHandles::resolve_external_guard(jobj));
1352     NULL_CHECK(ob_h, JVMTI_ERROR_INVALID_OBJECT);
1353     KlassHandle ob_kh = KlassHandle(current_thread, ob_h()->klass());
1354     NULL_CHECK(ob_kh, JVMTI_ERROR_INVALID_OBJECT);
1355 
1356     // Method return type signature.
1357     char* ty_sign = 1 + strchr(signature->as_C_string(), ')');
1358 
1359     if (!VM_GetOrSetLocal::is_assignable(ty_sign, ob_kh(), current_thread)) {
1360       return JVMTI_ERROR_TYPE_MISMATCH;
1361     }
1362     *ret_ob_h = ob_h;
1363   }
1364   return JVMTI_ERROR_NONE;
1365 } /* end check_top_frame */
1366 
1367 
1368 // ForceEarlyReturn<type> follows the PopFrame approach in many aspects.
1369 // Main difference is on the last stage in the interpreter.
1370 // The PopFrame stops method execution to continue execution
1371 // from the same method call instruction.
1372 // The ForceEarlyReturn forces return from method so the execution
1373 // continues at the bytecode following the method call.
1374 
1375 // Threads_lock NOT held, java_thread not protected by lock
1376 // java_thread - pre-checked
1377 
1378 jvmtiError
1379 JvmtiEnvBase::force_early_return(JavaThread* java_thread, jvalue value, TosState tos) {
1380   JavaThread* current_thread = JavaThread::current();
1381   HandleMark   hm(current_thread);
1382   uint32_t debug_bits = 0;
1383 
1384   // retrieve or create the state
1385   JvmtiThreadState* state = JvmtiThreadState::state_for(java_thread);
1386   if (state == NULL) {
1387     return JVMTI_ERROR_THREAD_NOT_ALIVE;
1388   }
1389 
1390   // Check if java_thread is fully suspended
1391   if (!is_thread_fully_suspended(java_thread,
1392                                  true /* wait for suspend completion */,
1393                                  &debug_bits)) {
1394     return JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1395   }
1396 
1397   // Check to see if a ForceEarlyReturn was already in progress
1398   if (state->is_earlyret_pending()) {
1399     // Probably possible for JVMTI clients to trigger this, but the
1400     // JPDA backend shouldn't allow this to happen
1401     return JVMTI_ERROR_INTERNAL;
1402   }
1403   {
1404     // The same as for PopFrame. Workaround bug:
1405     //  4812902: popFrame hangs if the method is waiting at a synchronize
1406     // Catch this condition and return an error to avoid hanging.
1407     // Now JVMTI spec allows an implementation to bail out with an opaque
1408     // frame error.
1409     OSThread* osThread = java_thread->osthread();
1410     if (osThread->get_state() == MONITOR_WAIT) {
1411       return JVMTI_ERROR_OPAQUE_FRAME;
1412     }
1413   }
1414   Handle ret_ob_h = Handle();
1415   jvmtiError err = check_top_frame(current_thread, java_thread, value, tos, &ret_ob_h);
1416   if (err != JVMTI_ERROR_NONE) {
1417     return err;
1418   }
1419   assert(tos != atos || value.l == NULL || ret_ob_h() != NULL,
1420          "return object oop must not be NULL if jobject is not NULL");
1421 
1422   // Update the thread state to reflect that the top frame must be
1423   // forced to return.
1424   // The current frame will be returned later when the suspended
1425   // thread is resumed and right before returning from VM to Java.
1426   // (see call_VM_base() in assembler_<cpu>.cpp).
1427 
1428   state->set_earlyret_pending();
1429   state->set_earlyret_oop(ret_ob_h());
1430   state->set_earlyret_value(value, tos);
1431 
1432   // Set pending step flag for this early return.
1433   // It is cleared when next step event is posted.
1434   state->set_pending_step_for_earlyret();
1435 
1436   return JVMTI_ERROR_NONE;
1437 } /* end force_early_return */
1438 
1439 void
1440 JvmtiMonitorClosure::do_monitor(ObjectMonitor* mon) {
1441   if ( _error != JVMTI_ERROR_NONE) {
1442     // Error occurred in previous iteration so no need to add
1443     // to the list.
1444     return;
1445   }
1446   if (mon->owner() == _java_thread ) {
1447     // Filter out on stack monitors collected during stack walk.
1448     oop obj = (oop)mon->object();
1449     bool found = false;
1450     for (int j = 0; j < _owned_monitors_list->length(); j++) {
1451       jobject jobj = ((jvmtiMonitorStackDepthInfo*)_owned_monitors_list->at(j))->monitor;
1452       oop check = JNIHandles::resolve(jobj);
1453       if (check == obj) {
1454         // On stack monitor already collected during the stack walk.
1455         found = true;
1456         break;
1457       }
1458     }
1459     if (found == false) {
1460       // This is off stack monitor (e.g. acquired via jni MonitorEnter).
1461       jvmtiError err;
1462       jvmtiMonitorStackDepthInfo *jmsdi;
1463       err = _env->allocate(sizeof(jvmtiMonitorStackDepthInfo), (unsigned char **)&jmsdi);
1464       if (err != JVMTI_ERROR_NONE) {
1465         _error = err;
1466         return;
1467       }
1468       Handle hobj(obj);
1469       jmsdi->monitor = _env->jni_reference(_calling_thread, hobj);
1470       // stack depth is unknown for this monitor.
1471       jmsdi->stack_depth = -1;
1472       _owned_monitors_list->append(jmsdi);
1473     }
1474   }
1475 }