1 /*
   2  * Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoaderDataGraph.hpp"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "jvmtifiles/jvmtiEnv.hpp"
  29 #include "memory/resourceArea.hpp"
  30 #include "oops/objArrayKlass.hpp"
  31 #include "oops/objArrayOop.hpp"
  32 #include "oops/oop.inline.hpp"
  33 #include "oops/oopHandle.inline.hpp"
  34 #include "prims/jvmtiEnvBase.hpp"
  35 #include "prims/jvmtiEventController.inline.hpp"
  36 #include "prims/jvmtiExtensions.hpp"
  37 #include "prims/jvmtiImpl.hpp"
  38 #include "prims/jvmtiManageCapabilities.hpp"
  39 #include "prims/jvmtiTagMap.hpp"
  40 #include "prims/jvmtiThreadState.inline.hpp"
  41 #include "runtime/biasedLocking.hpp"
  42 #include "runtime/deoptimization.hpp"
  43 #include "runtime/frame.inline.hpp"
  44 #include "runtime/interfaceSupport.inline.hpp"
  45 #include "runtime/jfieldIDWorkaround.hpp"
  46 #include "runtime/jniHandles.inline.hpp"
  47 #include "runtime/objectMonitor.hpp"
  48 #include "runtime/objectMonitor.inline.hpp"
  49 #include "runtime/signature.hpp"
  50 #include "runtime/thread.inline.hpp"
  51 #include "runtime/threadSMR.hpp"
  52 #include "runtime/vframe.hpp"
  53 #include "runtime/vframe_hp.hpp"
  54 #include "runtime/vmThread.hpp"
  55 #include "runtime/vm_operations.hpp"
  56 
  57 ///////////////////////////////////////////////////////////////
  58 //
  59 // JvmtiEnvBase
  60 //
  61 
  62 JvmtiEnvBase* JvmtiEnvBase::_head_environment = NULL;
  63 
  64 bool JvmtiEnvBase::_globally_initialized = false;
  65 volatile bool JvmtiEnvBase::_needs_clean_up = false;
  66 
  67 jvmtiPhase JvmtiEnvBase::_phase = JVMTI_PHASE_PRIMORDIAL;
  68 
  69 volatile int JvmtiEnvBase::_dying_thread_env_iteration_count = 0;
  70 
  71 extern jvmtiInterface_1_ jvmti_Interface;
  72 extern jvmtiInterface_1_ jvmtiTrace_Interface;
  73 
  74 
  75 // perform initializations that must occur before any JVMTI environments
  76 // are released but which should only be initialized once (no matter
  77 // how many environments are created).
  78 void
  79 JvmtiEnvBase::globally_initialize() {
  80   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
  81   assert(_globally_initialized == false, "bad call");
  82 
  83   JvmtiManageCapabilities::initialize();
  84 
  85   // register extension functions and events
  86   JvmtiExtensions::register_extensions();
  87 
  88 #ifdef JVMTI_TRACE
  89   JvmtiTrace::initialize();
  90 #endif
  91 
  92   _globally_initialized = true;
  93 }
  94 
  95 
  96 void
  97 JvmtiEnvBase::initialize() {
  98   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
  99 
 100   // Add this environment to the end of the environment list (order is important)
 101   {
 102     // This block of code must not contain any safepoints, as list deallocation
 103     // (which occurs at a safepoint) cannot occur simultaneously with this list
 104     // addition.  Note: NoSafepointVerifier cannot, currently, be used before
 105     // threads exist.
 106     JvmtiEnvIterator it;
 107     JvmtiEnvBase *previous_env = NULL;
 108     for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
 109       previous_env = env;
 110     }
 111     if (previous_env == NULL) {
 112       _head_environment = this;
 113     } else {
 114       previous_env->set_next_environment(this);
 115     }
 116   }
 117 
 118   if (_globally_initialized == false) {
 119     globally_initialize();
 120   }
 121 }
 122 
 123 jvmtiPhase
 124 JvmtiEnvBase::phase() {
 125   // For the JVMTI environments possessed the can_generate_early_vmstart:
 126   //   replace JVMTI_PHASE_PRIMORDIAL with JVMTI_PHASE_START
 127   if (_phase == JVMTI_PHASE_PRIMORDIAL &&
 128       JvmtiExport::early_vmstart_recorded() &&
 129       early_vmstart_env()) {
 130     return JVMTI_PHASE_START;
 131   }
 132   return _phase; // Normal case
 133 }
 134 
 135 bool
 136 JvmtiEnvBase::is_valid() {
 137   jint value = 0;
 138 
 139   // This object might not be a JvmtiEnvBase so we can't assume
 140   // the _magic field is properly aligned. Get the value in a safe
 141   // way and then check against JVMTI_MAGIC.
 142 
 143   switch (sizeof(_magic)) {
 144   case 2:
 145     value = Bytes::get_native_u2((address)&_magic);
 146     break;
 147 
 148   case 4:
 149     value = Bytes::get_native_u4((address)&_magic);
 150     break;
 151 
 152   case 8:
 153     value = Bytes::get_native_u8((address)&_magic);
 154     break;
 155 
 156   default:
 157     guarantee(false, "_magic field is an unexpected size");
 158   }
 159 
 160   return value == JVMTI_MAGIC;
 161 }
 162 
 163 
 164 bool
 165 JvmtiEnvBase::use_version_1_0_semantics() {
 166   int major, minor, micro;
 167 
 168   JvmtiExport::decode_version_values(_version, &major, &minor, &micro);
 169   return major == 1 && minor == 0;  // micro version doesn't matter here
 170 }
 171 
 172 
 173 bool
 174 JvmtiEnvBase::use_version_1_1_semantics() {
 175   int major, minor, micro;
 176 
 177   JvmtiExport::decode_version_values(_version, &major, &minor, &micro);
 178   return major == 1 && minor == 1;  // micro version doesn't matter here
 179 }
 180 
 181 bool
 182 JvmtiEnvBase::use_version_1_2_semantics() {
 183   int major, minor, micro;
 184 
 185   JvmtiExport::decode_version_values(_version, &major, &minor, &micro);
 186   return major == 1 && minor == 2;  // micro version doesn't matter here
 187 }
 188 
 189 
 190 JvmtiEnvBase::JvmtiEnvBase(jint version) : _env_event_enable() {
 191   _version = version;
 192   _env_local_storage = NULL;
 193   _tag_map = NULL;
 194   _native_method_prefix_count = 0;
 195   _native_method_prefixes = NULL;
 196   _next = NULL;
 197   _class_file_load_hook_ever_enabled = false;
 198 
 199   // Moot since ClassFileLoadHook not yet enabled.
 200   // But "true" will give a more predictable ClassFileLoadHook behavior
 201   // for environment creation during ClassFileLoadHook.
 202   _is_retransformable = true;
 203 
 204   // all callbacks initially NULL
 205   memset(&_event_callbacks,0,sizeof(jvmtiEventCallbacks));
 206 
 207   // all capabilities initially off
 208   memset(&_current_capabilities, 0, sizeof(_current_capabilities));
 209 
 210   // all prohibited capabilities initially off
 211   memset(&_prohibited_capabilities, 0, sizeof(_prohibited_capabilities));
 212 
 213   _magic = JVMTI_MAGIC;
 214 
 215   JvmtiEventController::env_initialize((JvmtiEnv*)this);
 216 
 217 #ifdef JVMTI_TRACE
 218   _jvmti_external.functions = TraceJVMTI != NULL ? &jvmtiTrace_Interface : &jvmti_Interface;
 219 #else
 220   _jvmti_external.functions = &jvmti_Interface;
 221 #endif
 222 }
 223 
 224 
 225 void
 226 JvmtiEnvBase::dispose() {
 227 
 228 #ifdef JVMTI_TRACE
 229   JvmtiTrace::shutdown();
 230 #endif
 231 
 232   // Dispose of event info and let the event controller call us back
 233   // in a locked state (env_dispose, below)
 234   JvmtiEventController::env_dispose(this);
 235 }
 236 
 237 void
 238 JvmtiEnvBase::env_dispose() {
 239   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
 240 
 241   // We have been entered with all events disabled on this environment.
 242   // A race to re-enable events (by setting callbacks) is prevented by
 243   // checking for a valid environment when setting callbacks (while
 244   // holding the JvmtiThreadState_lock).
 245 
 246   // Mark as invalid.
 247   _magic = DISPOSED_MAGIC;
 248 
 249   // Relinquish all capabilities.
 250   jvmtiCapabilities *caps = get_capabilities();
 251   JvmtiManageCapabilities::relinquish_capabilities(caps, caps, caps);
 252 
 253   // Same situation as with events (see above)
 254   set_native_method_prefixes(0, NULL);
 255 
 256   JvmtiTagMap* tag_map_to_deallocate = _tag_map;
 257   set_tag_map(NULL);
 258   // A tag map can be big, deallocate it now
 259   if (tag_map_to_deallocate != NULL) {
 260     delete tag_map_to_deallocate;
 261   }
 262 
 263   _needs_clean_up = true;
 264 }
 265 
 266 
 267 JvmtiEnvBase::~JvmtiEnvBase() {
 268   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
 269 
 270   // There is a small window of time during which the tag map of a
 271   // disposed environment could have been reallocated.
 272   // Make sure it is gone.
 273   JvmtiTagMap* tag_map_to_deallocate = _tag_map;
 274   set_tag_map(NULL);
 275   // A tag map can be big, deallocate it now
 276   if (tag_map_to_deallocate != NULL) {
 277     delete tag_map_to_deallocate;
 278   }
 279 
 280   _magic = BAD_MAGIC;
 281 }
 282 
 283 
 284 void
 285 JvmtiEnvBase::periodic_clean_up() {
 286   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
 287 
 288   // JvmtiEnvBase reference is saved in JvmtiEnvThreadState. So
 289   // clean up JvmtiThreadState before deleting JvmtiEnv pointer.
 290   JvmtiThreadState::periodic_clean_up();
 291 
 292   // Unlink all invalid environments from the list of environments
 293   // and deallocate them
 294   JvmtiEnvIterator it;
 295   JvmtiEnvBase* previous_env = NULL;
 296   JvmtiEnvBase* env = it.first();
 297   while (env != NULL) {
 298     if (env->is_valid()) {
 299       previous_env = env;
 300       env = it.next(env);
 301     } else {
 302       // This one isn't valid, remove it from the list and deallocate it
 303       JvmtiEnvBase* defunct_env = env;
 304       env = it.next(env);
 305       if (previous_env == NULL) {
 306         _head_environment = env;
 307       } else {
 308         previous_env->set_next_environment(env);
 309       }
 310       delete defunct_env;
 311     }
 312   }
 313 
 314 }
 315 
 316 
 317 void
 318 JvmtiEnvBase::check_for_periodic_clean_up() {
 319   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
 320 
 321   class ThreadInsideIterationClosure: public ThreadClosure {
 322    private:
 323     bool _inside;
 324    public:
 325     ThreadInsideIterationClosure() : _inside(false) {};
 326 
 327     void do_thread(Thread* thread) {
 328       _inside |= thread->is_inside_jvmti_env_iteration();
 329     }
 330 
 331     bool is_inside_jvmti_env_iteration() {
 332       return _inside;
 333     }
 334   };
 335 
 336   if (_needs_clean_up) {
 337     // Check if we are currently iterating environment,
 338     // deallocation should not occur if we are
 339     ThreadInsideIterationClosure tiic;
 340     Threads::threads_do(&tiic);
 341     if (!tiic.is_inside_jvmti_env_iteration() &&
 342              !is_inside_dying_thread_env_iteration()) {
 343       _needs_clean_up = false;
 344       JvmtiEnvBase::periodic_clean_up();
 345     }
 346   }
 347 }
 348 
 349 
 350 void
 351 JvmtiEnvBase::record_first_time_class_file_load_hook_enabled() {
 352   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(),
 353          "sanity check");
 354 
 355   if (!_class_file_load_hook_ever_enabled) {
 356     _class_file_load_hook_ever_enabled = true;
 357 
 358     if (get_capabilities()->can_retransform_classes) {
 359       _is_retransformable = true;
 360     } else {
 361       _is_retransformable = false;
 362 
 363       // cannot add retransform capability after ClassFileLoadHook has been enabled
 364       get_prohibited_capabilities()->can_retransform_classes = 1;
 365     }
 366   }
 367 }
 368 
 369 
 370 void
 371 JvmtiEnvBase::record_class_file_load_hook_enabled() {
 372   if (!_class_file_load_hook_ever_enabled) {
 373     if (Threads::number_of_threads() == 0) {
 374       record_first_time_class_file_load_hook_enabled();
 375     } else {
 376       MutexLocker mu(JvmtiThreadState_lock);
 377       record_first_time_class_file_load_hook_enabled();
 378     }
 379   }
 380 }
 381 
 382 
 383 jvmtiError
 384 JvmtiEnvBase::set_native_method_prefixes(jint prefix_count, char** prefixes) {
 385   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(),
 386          "sanity check");
 387 
 388   int old_prefix_count = get_native_method_prefix_count();
 389   char **old_prefixes = get_native_method_prefixes();
 390 
 391   // allocate and install the new prefixex
 392   if (prefix_count == 0 || !is_valid()) {
 393     _native_method_prefix_count = 0;
 394     _native_method_prefixes = NULL;
 395   } else {
 396     // there are prefixes, allocate an array to hold them, and fill it
 397     char** new_prefixes = (char**)os::malloc((prefix_count) * sizeof(char*), mtInternal);
 398     if (new_prefixes == NULL) {
 399       return JVMTI_ERROR_OUT_OF_MEMORY;
 400     }
 401     for (int i = 0; i < prefix_count; i++) {
 402       char* prefix = prefixes[i];
 403       if (prefix == NULL) {
 404         for (int j = 0; j < (i-1); j++) {
 405           os::free(new_prefixes[j]);
 406         }
 407         os::free(new_prefixes);
 408         return JVMTI_ERROR_NULL_POINTER;
 409       }
 410       prefix = os::strdup(prefixes[i]);
 411       if (prefix == NULL) {
 412         for (int j = 0; j < (i-1); j++) {
 413           os::free(new_prefixes[j]);
 414         }
 415         os::free(new_prefixes);
 416         return JVMTI_ERROR_OUT_OF_MEMORY;
 417       }
 418       new_prefixes[i] = prefix;
 419     }
 420     _native_method_prefix_count = prefix_count;
 421     _native_method_prefixes = new_prefixes;
 422   }
 423 
 424   // now that we know the new prefixes have been successfully installed we can
 425   // safely remove the old ones
 426   if (old_prefix_count != 0) {
 427     for (int i = 0; i < old_prefix_count; i++) {
 428       os::free(old_prefixes[i]);
 429     }
 430     os::free(old_prefixes);
 431   }
 432 
 433   return JVMTI_ERROR_NONE;
 434 }
 435 
 436 
 437 // Collect all the prefixes which have been set in any JVM TI environments
 438 // by the SetNativeMethodPrefix(es) functions.  Be sure to maintain the
 439 // order of environments and the order of prefixes within each environment.
 440 // Return in a resource allocated array.
 441 char**
 442 JvmtiEnvBase::get_all_native_method_prefixes(int* count_ptr) {
 443   assert(Threads::number_of_threads() == 0 ||
 444          SafepointSynchronize::is_at_safepoint() ||
 445          JvmtiThreadState_lock->is_locked(),
 446          "sanity check");
 447 
 448   int total_count = 0;
 449   GrowableArray<char*>* prefix_array =new GrowableArray<char*>(5);
 450 
 451   JvmtiEnvIterator it;
 452   for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
 453     int prefix_count = env->get_native_method_prefix_count();
 454     char** prefixes = env->get_native_method_prefixes();
 455     for (int j = 0; j < prefix_count; j++) {
 456       // retrieve a prefix and so that it is safe against asynchronous changes
 457       // copy it into the resource area
 458       char* prefix = prefixes[j];
 459       char* prefix_copy = NEW_RESOURCE_ARRAY(char, strlen(prefix)+1);
 460       strcpy(prefix_copy, prefix);
 461       prefix_array->at_put_grow(total_count++, prefix_copy);
 462     }
 463   }
 464 
 465   char** all_prefixes = NEW_RESOURCE_ARRAY(char*, total_count);
 466   char** p = all_prefixes;
 467   for (int i = 0; i < total_count; ++i) {
 468     *p++ = prefix_array->at(i);
 469   }
 470   *count_ptr = total_count;
 471   return all_prefixes;
 472 }
 473 
 474 void
 475 JvmtiEnvBase::set_event_callbacks(const jvmtiEventCallbacks* callbacks,
 476                                                jint size_of_callbacks) {
 477   assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
 478 
 479   size_t byte_cnt = sizeof(jvmtiEventCallbacks);
 480 
 481   // clear in either case to be sure we got any gap between sizes
 482   memset(&_event_callbacks, 0, byte_cnt);
 483 
 484   // Now that JvmtiThreadState_lock is held, prevent a possible race condition where events
 485   // are re-enabled by a call to set event callbacks where the DisposeEnvironment
 486   // occurs after the boiler-plate environment check and before the lock is acquired.
 487   if (callbacks != NULL && is_valid()) {
 488     if (size_of_callbacks < (jint)byte_cnt) {
 489       byte_cnt = size_of_callbacks;
 490     }
 491     memcpy(&_event_callbacks, callbacks, byte_cnt);
 492   }
 493 }
 494 
 495 
 496 // In the fullness of time, all users of the method should instead
 497 // directly use allocate, besides being cleaner and faster, this will
 498 // mean much better out of memory handling
 499 unsigned char *
 500 JvmtiEnvBase::jvmtiMalloc(jlong size) {
 501   unsigned char* mem = NULL;
 502   jvmtiError result = allocate(size, &mem);
 503   assert(result == JVMTI_ERROR_NONE, "Allocate failed");
 504   return mem;
 505 }
 506 
 507 
 508 // Handle management
 509 
 510 jobject JvmtiEnvBase::jni_reference(Handle hndl) {
 511   return JNIHandles::make_local(hndl());
 512 }
 513 
 514 jobject JvmtiEnvBase::jni_reference(JavaThread *thread, Handle hndl) {
 515   return JNIHandles::make_local(thread, hndl());
 516 }
 517 
 518 void JvmtiEnvBase::destroy_jni_reference(jobject jobj) {
 519   JNIHandles::destroy_local(jobj);
 520 }
 521 
 522 void JvmtiEnvBase::destroy_jni_reference(JavaThread *thread, jobject jobj) {
 523   JNIHandles::destroy_local(jobj); // thread is unused.
 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 // return the vframe on the specified thread and depth, NULL if no such frame
 556 vframe*
 557 JvmtiEnvBase::vframeFor(JavaThread* java_thread, jint depth) {
 558   if (!java_thread->has_last_Java_frame()) {
 559     return NULL;
 560   }
 561   RegisterMap reg_map(java_thread);
 562   vframe *vf = java_thread->last_java_vframe(&reg_map);
 563   int d = 0;
 564   while ((vf != NULL) && (d < depth)) {
 565     vf = vf->java_sender();
 566     d++;
 567   }
 568   return vf;
 569 }
 570 
 571 
 572 //
 573 // utilities: JNI objects
 574 //
 575 
 576 
 577 jclass
 578 JvmtiEnvBase::get_jni_class_non_null(Klass* k) {
 579   assert(k != NULL, "k != NULL");
 580   Thread *thread = Thread::current();
 581   return (jclass)jni_reference(Handle(thread, k->java_mirror()));
 582 }
 583 
 584 //
 585 // Field Information
 586 //
 587 
 588 bool
 589 JvmtiEnvBase::get_field_descriptor(Klass* k, jfieldID field, fieldDescriptor* fd) {
 590   if (!jfieldIDWorkaround::is_valid_jfieldID(k, field)) {
 591     return false;
 592   }
 593   bool found = false;
 594   if (jfieldIDWorkaround::is_static_jfieldID(field)) {
 595     JNIid* id = jfieldIDWorkaround::from_static_jfieldID(field);
 596     found = id->find_local_field(fd);
 597   } else {
 598     // Non-static field. The fieldID is really the offset of the field within the object.
 599     int offset = jfieldIDWorkaround::from_instance_jfieldID(k, field);
 600     found = InstanceKlass::cast(k)->find_field_from_offset(offset, false, fd);
 601   }
 602   return found;
 603 }
 604 
 605 //
 606 // Object Monitor Information
 607 //
 608 
 609 //
 610 // Count the number of objects for a lightweight monitor. The hobj
 611 // parameter is object that owns the monitor so this routine will
 612 // count the number of times the same object was locked by frames
 613 // in java_thread.
 614 //
 615 jint
 616 JvmtiEnvBase::count_locked_objects(JavaThread *java_thread, Handle hobj) {
 617   jint ret = 0;
 618   if (!java_thread->has_last_Java_frame()) {
 619     return ret;  // no Java frames so no monitors
 620   }
 621 
 622   ResourceMark rm;
 623   HandleMark   hm;
 624   RegisterMap  reg_map(java_thread);
 625 
 626   for(javaVFrame *jvf=java_thread->last_java_vframe(&reg_map); jvf != NULL;
 627                                                  jvf = jvf->java_sender()) {
 628     GrowableArray<MonitorInfo*>* mons = jvf->monitors();
 629     if (!mons->is_empty()) {
 630       for (int i = 0; i < mons->length(); i++) {
 631         MonitorInfo *mi = mons->at(i);
 632         if (mi->owner_is_scalar_replaced()) continue;
 633 
 634         // see if owner of the monitor is our object
 635         if (mi->owner() != NULL && mi->owner() == hobj()) {
 636           ret++;
 637         }
 638       }
 639     }
 640   }
 641   return ret;
 642 }
 643 
 644 
 645 
 646 jvmtiError
 647 JvmtiEnvBase::get_current_contended_monitor(JavaThread *calling_thread, JavaThread *java_thread, jobject *monitor_ptr) {
 648 #ifdef ASSERT
 649   uint32_t debug_bits = 0;
 650 #endif
 651   assert((SafepointSynchronize::is_at_safepoint() ||
 652           java_thread->is_thread_fully_suspended(false, &debug_bits)),
 653          "at safepoint or target thread is suspended");
 654   oop obj = NULL;
 655   ObjectMonitor *mon = java_thread->current_waiting_monitor();
 656   if (mon == NULL) {
 657     // thread is not doing an Object.wait() call
 658     mon = java_thread->current_pending_monitor();
 659     if (mon != NULL) {
 660       // The thread is trying to enter() or raw_enter() an ObjectMonitor.
 661       obj = (oop)mon->object();
 662       // If obj == NULL, then ObjectMonitor is raw which doesn't count
 663       // as contended for this API
 664     }
 665     // implied else: no contended ObjectMonitor
 666   } else {
 667     // thread is doing an Object.wait() call
 668     obj = (oop)mon->object();
 669     assert(obj != NULL, "Object.wait() should have an object");
 670   }
 671 
 672   if (obj == NULL) {
 673     *monitor_ptr = NULL;
 674   } else {
 675     HandleMark hm;
 676     Handle     hobj(Thread::current(), obj);
 677     *monitor_ptr = jni_reference(calling_thread, hobj);
 678   }
 679   return JVMTI_ERROR_NONE;
 680 }
 681 
 682 
 683 jvmtiError
 684 JvmtiEnvBase::get_owned_monitors(JavaThread *calling_thread, JavaThread* java_thread,
 685                                  GrowableArray<jvmtiMonitorStackDepthInfo*> *owned_monitors_list) {
 686   jvmtiError err = JVMTI_ERROR_NONE;
 687 #ifdef ASSERT
 688   uint32_t debug_bits = 0;
 689 #endif
 690   assert((SafepointSynchronize::is_at_safepoint() ||
 691           java_thread->is_thread_fully_suspended(false, &debug_bits)),
 692          "at safepoint or target thread is suspended");
 693 
 694   if (java_thread->has_last_Java_frame()) {
 695     ResourceMark rm;
 696     HandleMark   hm;
 697     RegisterMap  reg_map(java_thread);
 698 
 699     int depth = 0;
 700     for (javaVFrame *jvf = java_thread->last_java_vframe(&reg_map); jvf != NULL;
 701          jvf = jvf->java_sender()) {
 702       if (MaxJavaStackTraceDepth == 0 || depth++ < MaxJavaStackTraceDepth) {  // check for stack too deep
 703         // add locked objects for this frame into list
 704         err = get_locked_objects_in_frame(calling_thread, java_thread, jvf, owned_monitors_list, depth-1);
 705         if (err != JVMTI_ERROR_NONE) {
 706           return err;
 707         }
 708       }
 709     }
 710   }
 711 
 712   // Get off stack monitors. (e.g. acquired via jni MonitorEnter).
 713   JvmtiMonitorClosure jmc(java_thread, calling_thread, owned_monitors_list, this);
 714   ObjectSynchronizer::monitors_iterate(&jmc);
 715   err = jmc.error();
 716 
 717   return err;
 718 }
 719 
 720 // Save JNI local handles for any objects that this frame owns.
 721 jvmtiError
 722 JvmtiEnvBase::get_locked_objects_in_frame(JavaThread* calling_thread, JavaThread* java_thread,
 723                                  javaVFrame *jvf, GrowableArray<jvmtiMonitorStackDepthInfo*>* owned_monitors_list, jint stack_depth) {
 724   jvmtiError err = JVMTI_ERROR_NONE;
 725   ResourceMark rm;
 726 
 727   GrowableArray<MonitorInfo*>* mons = jvf->monitors();
 728   if (mons->is_empty()) {
 729     return err;  // this javaVFrame holds no monitors
 730   }
 731 
 732   HandleMark hm;
 733   oop wait_obj = NULL;
 734   {
 735     // save object of current wait() call (if any) for later comparison
 736     ObjectMonitor *mon = java_thread->current_waiting_monitor();
 737     if (mon != NULL) {
 738       wait_obj = (oop)mon->object();
 739     }
 740   }
 741   oop pending_obj = NULL;
 742   {
 743     // save object of current enter() call (if any) for later comparison
 744     ObjectMonitor *mon = java_thread->current_pending_monitor();
 745     if (mon != NULL) {
 746       pending_obj = (oop)mon->object();
 747     }
 748   }
 749 
 750   for (int i = 0; i < mons->length(); i++) {
 751     MonitorInfo *mi = mons->at(i);
 752 
 753     if (mi->owner_is_scalar_replaced()) continue;
 754 
 755     oop obj = mi->owner();
 756     if (obj == NULL) {
 757       // this monitor doesn't have an owning object so skip it
 758       continue;
 759     }
 760 
 761     if (wait_obj == obj) {
 762       // the thread is waiting on this monitor so it isn't really owned
 763       continue;
 764     }
 765 
 766     if (pending_obj == obj) {
 767       // the thread is pending on this monitor so it isn't really owned
 768       continue;
 769     }
 770 
 771     if (owned_monitors_list->length() > 0) {
 772       // Our list has at least one object on it so we have to check
 773       // for recursive object locking
 774       bool found = false;
 775       for (int j = 0; j < owned_monitors_list->length(); j++) {
 776         jobject jobj = ((jvmtiMonitorStackDepthInfo*)owned_monitors_list->at(j))->monitor;
 777         oop check = JNIHandles::resolve(jobj);
 778         if (check == obj) {
 779           found = true;  // we found the object
 780           break;
 781         }
 782       }
 783 
 784       if (found) {
 785         // already have this object so don't include it
 786         continue;
 787       }
 788     }
 789 
 790     // add the owning object to our list
 791     jvmtiMonitorStackDepthInfo *jmsdi;
 792     err = allocate(sizeof(jvmtiMonitorStackDepthInfo), (unsigned char **)&jmsdi);
 793     if (err != JVMTI_ERROR_NONE) {
 794         return err;
 795     }
 796     Handle hobj(Thread::current(), obj);
 797     jmsdi->monitor = jni_reference(calling_thread, hobj);
 798     jmsdi->stack_depth = stack_depth;
 799     owned_monitors_list->append(jmsdi);
 800   }
 801 
 802   return err;
 803 }
 804 
 805 jvmtiError
 806 JvmtiEnvBase::get_stack_trace(JavaThread *java_thread,
 807                               jint start_depth, jint max_count,
 808                               jvmtiFrameInfo* frame_buffer, jint* count_ptr) {
 809 #ifdef ASSERT
 810   uint32_t debug_bits = 0;
 811 #endif
 812   assert((SafepointSynchronize::is_at_safepoint() ||
 813           java_thread->is_thread_fully_suspended(false, &debug_bits)),
 814          "at safepoint or target thread is suspended");
 815   int count = 0;
 816   if (java_thread->has_last_Java_frame()) {
 817     RegisterMap reg_map(java_thread);
 818     Thread* current_thread = Thread::current();
 819     ResourceMark rm(current_thread);
 820     javaVFrame *jvf = java_thread->last_java_vframe(&reg_map);
 821     HandleMark hm(current_thread);
 822     if (start_depth != 0) {
 823       if (start_depth > 0) {
 824         for (int j = 0; j < start_depth && jvf != NULL; j++) {
 825           jvf = jvf->java_sender();
 826         }
 827         if (jvf == NULL) {
 828           // start_depth is deeper than the stack depth
 829           return JVMTI_ERROR_ILLEGAL_ARGUMENT;
 830         }
 831       } else { // start_depth < 0
 832         // we are referencing the starting depth based on the oldest
 833         // part of the stack.
 834         // optimize to limit the number of times that java_sender() is called
 835         javaVFrame *jvf_cursor = jvf;
 836         javaVFrame *jvf_prev = NULL;
 837         javaVFrame *jvf_prev_prev = NULL;
 838         int j = 0;
 839         while (jvf_cursor != NULL) {
 840           jvf_prev_prev = jvf_prev;
 841           jvf_prev = jvf_cursor;
 842           for (j = 0; j > start_depth && jvf_cursor != NULL; j--) {
 843             jvf_cursor = jvf_cursor->java_sender();
 844           }
 845         }
 846         if (j == start_depth) {
 847           // previous pointer is exactly where we want to start
 848           jvf = jvf_prev;
 849         } else {
 850           // we need to back up further to get to the right place
 851           if (jvf_prev_prev == NULL) {
 852             // the -start_depth is greater than the stack depth
 853             return JVMTI_ERROR_ILLEGAL_ARGUMENT;
 854           }
 855           // j now is the number of frames on the stack starting with
 856           // jvf_prev, we start from jvf_prev_prev and move older on
 857           // the stack that many, the result is -start_depth frames
 858           // remaining.
 859           jvf = jvf_prev_prev;
 860           for (; j < 0; j++) {
 861             jvf = jvf->java_sender();
 862           }
 863         }
 864       }
 865     }
 866     for (; count < max_count && jvf != NULL; count++) {
 867       frame_buffer[count].method = jvf->method()->jmethod_id();
 868       frame_buffer[count].location = (jvf->method()->is_native() ? -1 : jvf->bci());
 869       jvf = jvf->java_sender();
 870     }
 871   } else {
 872     if (start_depth != 0) {
 873       // no frames and there is a starting depth
 874       return JVMTI_ERROR_ILLEGAL_ARGUMENT;
 875     }
 876   }
 877   *count_ptr = count;
 878   return JVMTI_ERROR_NONE;
 879 }
 880 
 881 jvmtiError
 882 JvmtiEnvBase::get_frame_count(JvmtiThreadState *state, jint *count_ptr) {
 883   assert((state != NULL),
 884          "JavaThread should create JvmtiThreadState before calling this method");
 885   *count_ptr = state->count_frames();
 886   return JVMTI_ERROR_NONE;
 887 }
 888 
 889 jvmtiError
 890 JvmtiEnvBase::get_frame_location(JavaThread *java_thread, jint depth,
 891                                  jmethodID* method_ptr, jlocation* location_ptr) {
 892 #ifdef ASSERT
 893   uint32_t debug_bits = 0;
 894 #endif
 895   assert((SafepointSynchronize::is_at_safepoint() ||
 896           java_thread->is_thread_fully_suspended(false, &debug_bits)),
 897          "at safepoint or target thread is suspended");
 898   Thread* current_thread = Thread::current();
 899   ResourceMark rm(current_thread);
 900 
 901   vframe *vf = vframeFor(java_thread, depth);
 902   if (vf == NULL) {
 903     return JVMTI_ERROR_NO_MORE_FRAMES;
 904   }
 905 
 906   // vframeFor should return a java frame. If it doesn't
 907   // it means we've got an internal error and we return the
 908   // error in product mode. In debug mode we will instead
 909   // attempt to cast the vframe to a javaVFrame and will
 910   // cause an assertion/crash to allow further diagnosis.
 911 #ifdef PRODUCT
 912   if (!vf->is_java_frame()) {
 913     return JVMTI_ERROR_INTERNAL;
 914   }
 915 #endif
 916 
 917   HandleMark hm(current_thread);
 918   javaVFrame *jvf = javaVFrame::cast(vf);
 919   Method* method = jvf->method();
 920   if (method->is_native()) {
 921     *location_ptr = -1;
 922   } else {
 923     *location_ptr = jvf->bci();
 924   }
 925   *method_ptr = method->jmethod_id();
 926 
 927   return JVMTI_ERROR_NONE;
 928 }
 929 
 930 
 931 jvmtiError
 932 JvmtiEnvBase::get_object_monitor_usage(JavaThread* calling_thread, jobject object, jvmtiMonitorUsage* info_ptr) {
 933   HandleMark hm;
 934   Handle hobj;
 935 
 936   Thread* current_thread = Thread::current();
 937   bool at_safepoint = SafepointSynchronize::is_at_safepoint();
 938 
 939   // Check arguments
 940   {
 941     oop mirror = JNIHandles::resolve_external_guard(object);
 942     NULL_CHECK(mirror, JVMTI_ERROR_INVALID_OBJECT);
 943     NULL_CHECK(info_ptr, JVMTI_ERROR_NULL_POINTER);
 944 
 945     hobj = Handle(current_thread, mirror);
 946   }
 947 
 948   JavaThread *owning_thread = NULL;
 949   ObjectMonitor *mon = NULL;
 950   jvmtiMonitorUsage ret = {
 951       NULL, 0, 0, NULL, 0, NULL
 952   };
 953 
 954   uint32_t debug_bits = 0;
 955   // first derive the object's owner and entry_count (if any)
 956   {
 957     // Revoke any biases before querying the mark word
 958     if (at_safepoint) {
 959       BiasedLocking::revoke_at_safepoint(hobj);
 960     } else {
 961       BiasedLocking::revoke_and_rebias(hobj, false, calling_thread);
 962     }
 963 
 964     address owner = NULL;
 965     {
 966       markOop mark = hobj()->mark();
 967 
 968       if (!mark->has_monitor()) {
 969         // this object has a lightweight monitor
 970 
 971         if (mark->has_locker()) {
 972           owner = (address)mark->locker(); // save the address of the Lock word
 973         }
 974         // implied else: no owner
 975       } else {
 976         // this object has a heavyweight monitor
 977         mon = mark->monitor();
 978 
 979         // The owner field of a heavyweight monitor may be NULL for no
 980         // owner, a JavaThread * or it may still be the address of the
 981         // Lock word in a JavaThread's stack. A monitor can be inflated
 982         // by a non-owning JavaThread, but only the owning JavaThread
 983         // can change the owner field from the Lock word to the
 984         // JavaThread * and it may not have done that yet.
 985         owner = (address)mon->owner();
 986       }
 987     }
 988 
 989     if (owner != NULL) {
 990       // Use current thread since function can be called from a
 991       // JavaThread or the VMThread.
 992       ThreadsListHandle tlh;
 993       // This monitor is owned so we have to find the owning JavaThread.
 994       owning_thread = Threads::owning_thread_from_monitor_owner(tlh.list(), owner);
 995       // Cannot assume (owning_thread != NULL) here because this function
 996       // may not have been called at a safepoint and the owning_thread
 997       // might not be suspended.
 998       if (owning_thread != NULL) {
 999         // The monitor's owner either has to be the current thread, at safepoint
1000         // or it has to be suspended. Any of these conditions will prevent both
1001         // contending and waiting threads from modifying the state of
1002         // the monitor.
1003         if (!at_safepoint && !owning_thread->is_thread_fully_suspended(true, &debug_bits)) {
1004           // Don't worry! This return of JVMTI_ERROR_THREAD_NOT_SUSPENDED
1005           // will not make it back to the JVM/TI agent. The error code will
1006           // get intercepted in JvmtiEnv::GetObjectMonitorUsage() which
1007           // will retry the call via a VM_GetObjectMonitorUsage VM op.
1008           return JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1009         }
1010         HandleMark hm;
1011         Handle     th(current_thread, owning_thread->threadObj());
1012         ret.owner = (jthread)jni_reference(calling_thread, th);
1013       }
1014       // implied else: no owner
1015     } // ThreadsListHandle is destroyed here.
1016 
1017     if (owning_thread != NULL) {  // monitor is owned
1018       // The recursions field of a monitor does not reflect recursions
1019       // as lightweight locks before inflating the monitor are not included.
1020       // We have to count the number of recursive monitor entries the hard way.
1021       // We pass a handle to survive any GCs along the way.
1022       ResourceMark rm;
1023       ret.entry_count = count_locked_objects(owning_thread, hobj);
1024     }
1025     // implied else: entry_count == 0
1026   }
1027 
1028   jint nWant = 0, nWait = 0;
1029   if (mon != NULL) {
1030     // this object has a heavyweight monitor
1031     nWant = mon->contentions(); // # of threads contending for monitor
1032     nWait = mon->waiters();     // # of threads in Object.wait()
1033     ret.waiter_count = nWant + nWait;
1034     ret.notify_waiter_count = nWait;
1035   } else {
1036     // this object has a lightweight monitor
1037     ret.waiter_count = 0;
1038     ret.notify_waiter_count = 0;
1039   }
1040 
1041   // Allocate memory for heavyweight and lightweight monitor.
1042   jvmtiError err;
1043   err = allocate(ret.waiter_count * sizeof(jthread *), (unsigned char**)&ret.waiters);
1044   if (err != JVMTI_ERROR_NONE) {
1045     return err;
1046   }
1047   err = allocate(ret.notify_waiter_count * sizeof(jthread *),
1048                  (unsigned char**)&ret.notify_waiters);
1049   if (err != JVMTI_ERROR_NONE) {
1050     deallocate((unsigned char*)ret.waiters);
1051     return err;
1052   }
1053 
1054   // now derive the rest of the fields
1055   if (mon != NULL) {
1056     // this object has a heavyweight monitor
1057 
1058     // Number of waiters may actually be less than the waiter count.
1059     // So NULL out memory so that unused memory will be NULL.
1060     memset(ret.waiters, 0, ret.waiter_count * sizeof(jthread *));
1061     memset(ret.notify_waiters, 0, ret.notify_waiter_count * sizeof(jthread *));
1062 
1063     if (ret.waiter_count > 0) {
1064       // we have contending and/or waiting threads
1065       HandleMark hm;
1066       // Use current thread since function can be called from a
1067       // JavaThread or the VMThread.
1068       ThreadsListHandle tlh;
1069       if (nWant > 0) {
1070         // we have contending threads
1071         ResourceMark rm;
1072         // get_pending_threads returns only java thread so we do not need to
1073         // check for non java threads.
1074         GrowableArray<JavaThread*>* wantList = Threads::get_pending_threads(tlh.list(), nWant, (address)mon);
1075         if (wantList->length() < nWant) {
1076           // robustness: the pending list has gotten smaller
1077           nWant = wantList->length();
1078         }
1079         for (int i = 0; i < nWant; i++) {
1080           JavaThread *pending_thread = wantList->at(i);
1081           // If the monitor has no owner, then a non-suspended contending
1082           // thread could potentially change the state of the monitor by
1083           // entering it. The JVM/TI spec doesn't allow this.
1084           if (owning_thread == NULL && !at_safepoint &
1085               !pending_thread->is_thread_fully_suspended(true, &debug_bits)) {
1086             if (ret.owner != NULL) {
1087               destroy_jni_reference(calling_thread, ret.owner);
1088             }
1089             for (int j = 0; j < i; j++) {
1090               destroy_jni_reference(calling_thread, ret.waiters[j]);
1091             }
1092             deallocate((unsigned char*)ret.waiters);
1093             deallocate((unsigned char*)ret.notify_waiters);
1094             return JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1095           }
1096           Handle th(current_thread, pending_thread->threadObj());
1097           ret.waiters[i] = (jthread)jni_reference(calling_thread, th);
1098         }
1099       }
1100       if (nWait > 0) {
1101         // we have threads in Object.wait()
1102         int offset = nWant;  // add after any contending threads
1103         ObjectWaiter *waiter = mon->first_waiter();
1104         for (int i = 0, j = 0; i < nWait; i++) {
1105           if (waiter == NULL) {
1106             // robustness: the waiting list has gotten smaller
1107             nWait = j;
1108             break;
1109           }
1110           Thread *t = mon->thread_of_waiter(waiter);
1111           if (t != NULL && t->is_Java_thread()) {
1112             JavaThread *wjava_thread = (JavaThread *)t;
1113             // If the thread was found on the ObjectWaiter list, then
1114             // it has not been notified. This thread can't change the
1115             // state of the monitor so it doesn't need to be suspended.
1116             Handle th(current_thread, wjava_thread->threadObj());
1117             ret.waiters[offset + j] = (jthread)jni_reference(calling_thread, th);
1118             ret.notify_waiters[j++] = (jthread)jni_reference(calling_thread, th);
1119           }
1120           waiter = mon->next_waiter(waiter);
1121         }
1122       }
1123     } // ThreadsListHandle is destroyed here.
1124 
1125     // Adjust count. nWant and nWait count values may be less than original.
1126     ret.waiter_count = nWant + nWait;
1127     ret.notify_waiter_count = nWait;
1128   } else {
1129     // this object has a lightweight monitor and we have nothing more
1130     // to do here because the defaults are just fine.
1131   }
1132 
1133   // we don't update return parameter unless everything worked
1134   *info_ptr = ret;
1135 
1136   return JVMTI_ERROR_NONE;
1137 }
1138 
1139 ResourceTracker::ResourceTracker(JvmtiEnv* env) {
1140   _env = env;
1141   _allocations = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<unsigned char*>(20, true);
1142   _failed = false;
1143 }
1144 ResourceTracker::~ResourceTracker() {
1145   if (_failed) {
1146     for (int i=0; i<_allocations->length(); i++) {
1147       _env->deallocate(_allocations->at(i));
1148     }
1149   }
1150   delete _allocations;
1151 }
1152 
1153 jvmtiError ResourceTracker::allocate(jlong size, unsigned char** mem_ptr) {
1154   unsigned char *ptr;
1155   jvmtiError err = _env->allocate(size, &ptr);
1156   if (err == JVMTI_ERROR_NONE) {
1157     _allocations->append(ptr);
1158     *mem_ptr = ptr;
1159   } else {
1160     *mem_ptr = NULL;
1161     _failed = true;
1162   }
1163   return err;
1164  }
1165 
1166 unsigned char* ResourceTracker::allocate(jlong size) {
1167   unsigned char* ptr;
1168   allocate(size, &ptr);
1169   return ptr;
1170 }
1171 
1172 char* ResourceTracker::strdup(const char* str) {
1173   char *dup_str = (char*)allocate(strlen(str)+1);
1174   if (dup_str != NULL) {
1175     strcpy(dup_str, str);
1176   }
1177   return dup_str;
1178 }
1179 
1180 struct StackInfoNode {
1181   struct StackInfoNode *next;
1182   jvmtiStackInfo info;
1183 };
1184 
1185 // Create a jvmtiStackInfo inside a linked list node and create a
1186 // buffer for the frame information, both allocated as resource objects.
1187 // Fill in both the jvmtiStackInfo and the jvmtiFrameInfo.
1188 // Note that either or both of thr and thread_oop
1189 // may be null if the thread is new or has exited.
1190 void
1191 VM_GetMultipleStackTraces::fill_frames(jthread jt, JavaThread *thr, oop thread_oop) {
1192   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1193 
1194   jint state = 0;
1195   struct StackInfoNode *node = NEW_RESOURCE_OBJ(struct StackInfoNode);
1196   jvmtiStackInfo *infop = &(node->info);
1197   node->next = head();
1198   set_head(node);
1199   infop->frame_count = 0;
1200   infop->thread = jt;
1201 
1202   if (thread_oop != NULL) {
1203     // get most state bits
1204     state = (jint)java_lang_Thread::get_thread_status(thread_oop);
1205   }
1206 
1207   if (thr != NULL) {    // add more state bits if there is a JavaThead to query
1208     // same as is_being_ext_suspended() but without locking
1209     if (thr->is_ext_suspended() || thr->is_external_suspend()) {
1210       state |= JVMTI_THREAD_STATE_SUSPENDED;
1211     }
1212     JavaThreadState jts = thr->thread_state();
1213     if (jts == _thread_in_native) {
1214       state |= JVMTI_THREAD_STATE_IN_NATIVE;
1215     }
1216     OSThread* osThread = thr->osthread();
1217     if (osThread != NULL && osThread->interrupted()) {
1218       state |= JVMTI_THREAD_STATE_INTERRUPTED;
1219     }
1220   }
1221   infop->state = state;
1222 
1223   if (thr != NULL && (state & JVMTI_THREAD_STATE_ALIVE) != 0) {
1224     infop->frame_buffer = NEW_RESOURCE_ARRAY(jvmtiFrameInfo, max_frame_count());
1225     env()->get_stack_trace(thr, 0, max_frame_count(),
1226                            infop->frame_buffer, &(infop->frame_count));
1227   } else {
1228     infop->frame_buffer = NULL;
1229     infop->frame_count = 0;
1230   }
1231   _frame_count_total += infop->frame_count;
1232 }
1233 
1234 // Based on the stack information in the linked list, allocate memory
1235 // block to return and fill it from the info in the linked list.
1236 void
1237 VM_GetMultipleStackTraces::allocate_and_fill_stacks(jint thread_count) {
1238   // do I need to worry about alignment issues?
1239   jlong alloc_size =  thread_count       * sizeof(jvmtiStackInfo)
1240                     + _frame_count_total * sizeof(jvmtiFrameInfo);
1241   env()->allocate(alloc_size, (unsigned char **)&_stack_info);
1242 
1243   // pointers to move through the newly allocated space as it is filled in
1244   jvmtiStackInfo *si = _stack_info + thread_count;      // bottom of stack info
1245   jvmtiFrameInfo *fi = (jvmtiFrameInfo *)si;            // is the top of frame info
1246 
1247   // copy information in resource area into allocated buffer
1248   // insert stack info backwards since linked list is backwards
1249   // insert frame info forwards
1250   // walk the StackInfoNodes
1251   for (struct StackInfoNode *sin = head(); sin != NULL; sin = sin->next) {
1252     jint frame_count = sin->info.frame_count;
1253     size_t frames_size = frame_count * sizeof(jvmtiFrameInfo);
1254     --si;
1255     memcpy(si, &(sin->info), sizeof(jvmtiStackInfo));
1256     if (frames_size == 0) {
1257       si->frame_buffer = NULL;
1258     } else {
1259       memcpy(fi, sin->info.frame_buffer, frames_size);
1260       si->frame_buffer = fi;  // point to the new allocated copy of the frames
1261       fi += frame_count;
1262     }
1263   }
1264   assert(si == _stack_info, "the last copied stack info must be the first record");
1265   assert((unsigned char *)fi == ((unsigned char *)_stack_info) + alloc_size,
1266          "the last copied frame info must be the last record");
1267 }
1268 
1269 
1270 void
1271 VM_GetThreadListStackTraces::doit() {
1272   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1273 
1274   ResourceMark rm;
1275   ThreadsListHandle tlh;
1276   for (int i = 0; i < _thread_count; ++i) {
1277     jthread jt = _thread_list[i];
1278     JavaThread* java_thread = NULL;
1279     oop thread_oop = NULL;
1280     jvmtiError err = JvmtiExport::cv_external_thread_to_JavaThread(tlh.list(), jt, &java_thread, &thread_oop);
1281     if (err != JVMTI_ERROR_NONE) {
1282       // We got an error code so we don't have a JavaThread *, but
1283       // only return an error from here if we didn't get a valid
1284       // thread_oop.
1285       if (thread_oop == NULL) {
1286         set_result(err);
1287         return;
1288       }
1289       // We have a valid thread_oop.
1290     }
1291     fill_frames(jt, java_thread, thread_oop);
1292   }
1293   allocate_and_fill_stacks(_thread_count);
1294 }
1295 
1296 void
1297 VM_GetAllStackTraces::doit() {
1298   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
1299 
1300   ResourceMark rm;
1301   _final_thread_count = 0;
1302   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
1303     oop thread_oop = jt->threadObj();
1304     if (thread_oop != NULL &&
1305         !jt->is_exiting() &&
1306         java_lang_Thread::is_alive(thread_oop) &&
1307         !jt->is_hidden_from_external_view()) {
1308       ++_final_thread_count;
1309       // Handle block of the calling thread is used to create local refs.
1310       fill_frames((jthread)JNIHandles::make_local(_calling_thread, thread_oop),
1311                   jt, thread_oop);
1312     }
1313   }
1314   allocate_and_fill_stacks(_final_thread_count);
1315 }
1316 
1317 // Verifies that the top frame is a java frame in an expected state.
1318 // Deoptimizes frame if needed.
1319 // Checks that the frame method signature matches the return type (tos).
1320 // HandleMark must be defined in the caller only.
1321 // It is to keep a ret_ob_h handle alive after return to the caller.
1322 jvmtiError
1323 JvmtiEnvBase::check_top_frame(JavaThread* current_thread, JavaThread* java_thread,
1324                               jvalue value, TosState tos, Handle* ret_ob_h) {
1325   ResourceMark rm(current_thread);
1326 
1327   vframe *vf = vframeFor(java_thread, 0);
1328   NULL_CHECK(vf, JVMTI_ERROR_NO_MORE_FRAMES);
1329 
1330   javaVFrame *jvf = (javaVFrame*) vf;
1331   if (!vf->is_java_frame() || jvf->method()->is_native()) {
1332     return JVMTI_ERROR_OPAQUE_FRAME;
1333   }
1334 
1335   // If the frame is a compiled one, need to deoptimize it.
1336   if (vf->is_compiled_frame()) {
1337     if (!vf->fr().can_be_deoptimized()) {
1338       return JVMTI_ERROR_OPAQUE_FRAME;
1339     }
1340     Deoptimization::deoptimize_frame(java_thread, jvf->fr().id());
1341   }
1342 
1343   // Get information about method return type
1344   Symbol* signature = jvf->method()->signature();
1345 
1346   ResultTypeFinder rtf(signature);
1347   TosState fr_tos = as_TosState(rtf.type());
1348   if (fr_tos != tos) {
1349     if (tos != itos || (fr_tos != btos && fr_tos != ztos && fr_tos != ctos && fr_tos != stos)) {
1350       return JVMTI_ERROR_TYPE_MISMATCH;
1351     }
1352   }
1353 
1354   // Check that the jobject class matches the return type signature.
1355   jobject jobj = value.l;
1356   if (tos == atos && jobj != NULL) { // NULL reference is allowed
1357     Handle ob_h(current_thread, JNIHandles::resolve_external_guard(jobj));
1358     NULL_CHECK(ob_h, JVMTI_ERROR_INVALID_OBJECT);
1359     Klass* ob_k = ob_h()->klass();
1360     NULL_CHECK(ob_k, JVMTI_ERROR_INVALID_OBJECT);
1361 
1362     // Method return type signature.
1363     char* ty_sign = 1 + strchr(signature->as_C_string(), ')');
1364 
1365     if (!VM_GetOrSetLocal::is_assignable(ty_sign, ob_k, current_thread)) {
1366       return JVMTI_ERROR_TYPE_MISMATCH;
1367     }
1368     *ret_ob_h = ob_h;
1369   }
1370   return JVMTI_ERROR_NONE;
1371 } /* end check_top_frame */
1372 
1373 
1374 // ForceEarlyReturn<type> follows the PopFrame approach in many aspects.
1375 // Main difference is on the last stage in the interpreter.
1376 // The PopFrame stops method execution to continue execution
1377 // from the same method call instruction.
1378 // The ForceEarlyReturn forces return from method so the execution
1379 // continues at the bytecode following the method call.
1380 
1381 // Threads_lock NOT held, java_thread not protected by lock
1382 // java_thread - pre-checked
1383 
1384 jvmtiError
1385 JvmtiEnvBase::force_early_return(JavaThread* java_thread, jvalue value, TosState tos) {
1386   JavaThread* current_thread = JavaThread::current();
1387   HandleMark   hm(current_thread);
1388   uint32_t debug_bits = 0;
1389 
1390   // retrieve or create the state
1391   JvmtiThreadState* state = JvmtiThreadState::state_for(java_thread);
1392   if (state == NULL) {
1393     return JVMTI_ERROR_THREAD_NOT_ALIVE;
1394   }
1395 
1396   // Check if java_thread is fully suspended
1397   if (!java_thread->is_thread_fully_suspended(true /* wait for suspend completion */, &debug_bits)) {
1398     return JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1399   }
1400 
1401   // Check to see if a ForceEarlyReturn was already in progress
1402   if (state->is_earlyret_pending()) {
1403     // Probably possible for JVMTI clients to trigger this, but the
1404     // JPDA backend shouldn't allow this to happen
1405     return JVMTI_ERROR_INTERNAL;
1406   }
1407   {
1408     // The same as for PopFrame. Workaround bug:
1409     //  4812902: popFrame hangs if the method is waiting at a synchronize
1410     // Catch this condition and return an error to avoid hanging.
1411     // Now JVMTI spec allows an implementation to bail out with an opaque
1412     // frame error.
1413     OSThread* osThread = java_thread->osthread();
1414     if (osThread->get_state() == MONITOR_WAIT) {
1415       return JVMTI_ERROR_OPAQUE_FRAME;
1416     }
1417   }
1418   Handle ret_ob_h;
1419   jvmtiError err = check_top_frame(current_thread, java_thread, value, tos, &ret_ob_h);
1420   if (err != JVMTI_ERROR_NONE) {
1421     return err;
1422   }
1423   assert(tos != atos || value.l == NULL || ret_ob_h() != NULL,
1424          "return object oop must not be NULL if jobject is not NULL");
1425 
1426   // Update the thread state to reflect that the top frame must be
1427   // forced to return.
1428   // The current frame will be returned later when the suspended
1429   // thread is resumed and right before returning from VM to Java.
1430   // (see call_VM_base() in assembler_<cpu>.cpp).
1431 
1432   state->set_earlyret_pending();
1433   state->set_earlyret_oop(ret_ob_h());
1434   state->set_earlyret_value(value, tos);
1435 
1436   // Set pending step flag for this early return.
1437   // It is cleared when next step event is posted.
1438   state->set_pending_step_for_earlyret();
1439 
1440   return JVMTI_ERROR_NONE;
1441 } /* end force_early_return */
1442 
1443 void
1444 JvmtiMonitorClosure::do_monitor(ObjectMonitor* mon) {
1445   if ( _error != JVMTI_ERROR_NONE) {
1446     // Error occurred in previous iteration so no need to add
1447     // to the list.
1448     return;
1449   }
1450   if (mon->owner() == _java_thread ) {
1451     // Filter out on stack monitors collected during stack walk.
1452     oop obj = (oop)mon->object();
1453     bool found = false;
1454     for (int j = 0; j < _owned_monitors_list->length(); j++) {
1455       jobject jobj = ((jvmtiMonitorStackDepthInfo*)_owned_monitors_list->at(j))->monitor;
1456       oop check = JNIHandles::resolve(jobj);
1457       if (check == obj) {
1458         // On stack monitor already collected during the stack walk.
1459         found = true;
1460         break;
1461       }
1462     }
1463     if (found == false) {
1464       // This is off stack monitor (e.g. acquired via jni MonitorEnter).
1465       jvmtiError err;
1466       jvmtiMonitorStackDepthInfo *jmsdi;
1467       err = _env->allocate(sizeof(jvmtiMonitorStackDepthInfo), (unsigned char **)&jmsdi);
1468       if (err != JVMTI_ERROR_NONE) {
1469         _error = err;
1470         return;
1471       }
1472       Handle hobj(Thread::current(), obj);
1473       jmsdi->monitor = _env->jni_reference(_calling_thread, hobj);
1474       // stack depth is unknown for this monitor.
1475       jmsdi->stack_depth = -1;
1476       _owned_monitors_list->append(jmsdi);
1477     }
1478   }
1479 }
1480 
1481 GrowableArray<OopHandle>* JvmtiModuleClosure::_tbl = NULL;
1482 
1483 void JvmtiModuleClosure::do_module(ModuleEntry* entry) {
1484   assert_locked_or_safepoint(Module_lock);
1485   OopHandle module = entry->module_handle();
1486   guarantee(module.resolve() != NULL, "module object is NULL");
1487   _tbl->push(module);
1488 }
1489 
1490 jvmtiError
1491 JvmtiModuleClosure::get_all_modules(JvmtiEnv* env, jint* module_count_ptr, jobject** modules_ptr) {
1492   ResourceMark rm;
1493   MutexLocker mcld(ClassLoaderDataGraph_lock);
1494   MutexLocker ml(Module_lock);
1495 
1496   _tbl = new GrowableArray<OopHandle>(77);
1497   if (_tbl == NULL) {
1498     return JVMTI_ERROR_OUT_OF_MEMORY;
1499   }
1500 
1501   // Iterate over all the modules loaded to the system.
1502   ClassLoaderDataGraph::modules_do(&do_module);
1503 
1504   jint len = _tbl->length();
1505   guarantee(len > 0, "at least one module must be present");
1506 
1507   jobject* array = (jobject*)env->jvmtiMalloc((jlong)(len * sizeof(jobject)));
1508   if (array == NULL) {
1509     return JVMTI_ERROR_OUT_OF_MEMORY;
1510   }
1511   for (jint idx = 0; idx < len; idx++) {
1512     array[idx] = JNIHandles::make_local(Thread::current(), _tbl->at(idx).resolve());
1513   }
1514   _tbl = NULL;
1515   *modules_ptr = array;
1516   *module_count_ptr = len;
1517   return JVMTI_ERROR_NONE;
1518 }
1519 
1520 void
1521 VM_UpdateForPopTopFrame::doit() {
1522   JavaThread* jt = _state->get_thread();
1523   ThreadsListHandle tlh;
1524   if (jt != NULL && tlh.includes(jt) && !jt->is_exiting() && jt->threadObj() != NULL) {
1525     _state->update_for_pop_top_frame();
1526   } else {
1527     _result = JVMTI_ERROR_THREAD_NOT_ALIVE;
1528   }
1529 }
1530 
1531 void
1532 VM_SetFramePop::doit() {
1533   JavaThread* jt = _state->get_thread();
1534   ThreadsListHandle tlh;
1535   if (jt != NULL && tlh.includes(jt) && !jt->is_exiting() && jt->threadObj() != NULL) {
1536     int frame_number = _state->count_frames() - _depth;
1537     _state->env_thread_state((JvmtiEnvBase*)_env)->set_frame_pop(frame_number);
1538   } else {
1539     _result = JVMTI_ERROR_THREAD_NOT_ALIVE;
1540   }
1541 }
1542 
1543 void
1544 VM_GetOwnedMonitorInfo::doit() {
1545   _result = JVMTI_ERROR_THREAD_NOT_ALIVE;
1546   ThreadsListHandle tlh;
1547   if (_java_thread != NULL && tlh.includes(_java_thread)
1548       && !_java_thread->is_exiting() && _java_thread->threadObj() != NULL) {
1549     _result = ((JvmtiEnvBase *)_env)->get_owned_monitors(_calling_thread, _java_thread,
1550                                                           _owned_monitors_list);
1551   }
1552 }
1553 
1554 void
1555 VM_GetCurrentContendedMonitor::doit() {
1556   _result = JVMTI_ERROR_THREAD_NOT_ALIVE;
1557   ThreadsListHandle tlh;
1558   if (_java_thread != NULL && tlh.includes(_java_thread)
1559       && !_java_thread->is_exiting() && _java_thread->threadObj() != NULL) {
1560     _result = ((JvmtiEnvBase *)_env)->get_current_contended_monitor(_calling_thread,_java_thread,_owned_monitor_ptr);
1561   }
1562 }
1563 
1564 void
1565 VM_GetStackTrace::doit() {
1566   _result = JVMTI_ERROR_THREAD_NOT_ALIVE;
1567   ThreadsListHandle tlh;
1568   if (_java_thread != NULL && tlh.includes(_java_thread)
1569       && !_java_thread->is_exiting() && _java_thread->threadObj() != NULL) {
1570     _result = ((JvmtiEnvBase *)_env)->get_stack_trace(_java_thread,
1571                                                       _start_depth, _max_count,
1572                                                       _frame_buffer, _count_ptr);
1573   }
1574 }
1575 
1576 void
1577 VM_GetFrameCount::doit() {
1578   _result = JVMTI_ERROR_THREAD_NOT_ALIVE;
1579   JavaThread* jt = _state->get_thread();
1580   ThreadsListHandle tlh;
1581   if (jt != NULL && tlh.includes(jt) && !jt->is_exiting() && jt->threadObj() != NULL) {
1582     _result = ((JvmtiEnvBase*)_env)->get_frame_count(_state, _count_ptr);
1583   }
1584 }
1585 
1586 void
1587 VM_GetFrameLocation::doit() {
1588   _result = JVMTI_ERROR_THREAD_NOT_ALIVE;
1589   ThreadsListHandle tlh;
1590   if (_java_thread != NULL && tlh.includes(_java_thread)
1591       && !_java_thread->is_exiting() && _java_thread->threadObj() != NULL) {
1592     _result = ((JvmtiEnvBase*)_env)->get_frame_location(_java_thread, _depth,
1593                                                         _method_ptr, _location_ptr);
1594   }
1595 }