1 /*
   2  * Copyright (c) 2012, 2013, 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 
  27 #include "memory/universe.hpp"
  28 #include "oops/oop.inline.hpp"
  29 
  30 #include "classfile/symbolTable.hpp"
  31 #include "classfile/classLoaderData.hpp"
  32 
  33 #include "prims/whitebox.hpp"
  34 #include "prims/wbtestmethods/parserTests.hpp"
  35 
  36 #include "runtime/interfaceSupport.hpp"
  37 #include "runtime/os.hpp"
  38 #include "utilities/debug.hpp"
  39 #include "utilities/macros.hpp"
  40 #include "utilities/exceptions.hpp"
  41 
  42 #if INCLUDE_ALL_GCS
  43 #include "gc_implementation/g1/concurrentMark.hpp"
  44 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  45 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  46 #endif // INCLUDE_ALL_GCS
  47 
  48 #ifdef INCLUDE_NMT
  49 #include "services/memTracker.hpp"
  50 #endif // INCLUDE_NMT
  51 
  52 #include "compiler/compileBroker.hpp"
  53 #include "runtime/compilationPolicy.hpp"
  54 
  55 bool WhiteBox::_used = false;
  56 
  57 WB_ENTRY(jlong, WB_GetObjectAddress(JNIEnv* env, jobject o, jobject obj))
  58   return (jlong)(void*)JNIHandles::resolve(obj);
  59 WB_END
  60 
  61 WB_ENTRY(jint, WB_GetHeapOopSize(JNIEnv* env, jobject o))
  62   return heapOopSize;
  63 WB_END
  64 
  65 
  66 class WBIsKlassAliveClosure : public KlassClosure {
  67     Symbol* _name;
  68     bool _found;
  69 public:
  70     WBIsKlassAliveClosure(Symbol* name) : _name(name), _found(false) {}
  71 
  72     void do_klass(Klass* k) {
  73       if (_found) return;
  74       Symbol* ksym = k->name();
  75       if (ksym->fast_compare(_name) == 0) {
  76         _found = true;
  77       }
  78     }
  79 
  80     bool found() const {
  81         return _found;
  82     }
  83 };
  84 
  85 WB_ENTRY(jboolean, WB_IsClassAlive(JNIEnv* env, jobject target, jstring name))
  86   Handle h_name = JNIHandles::resolve(name);
  87   if (h_name.is_null()) return false;
  88   Symbol* sym = java_lang_String::as_symbol(h_name, CHECK_false);
  89   TempNewSymbol tsym(sym); // Make sure to decrement reference count on sym on return
  90 
  91   WBIsKlassAliveClosure closure(sym);
  92   ClassLoaderDataGraph::classes_do(&closure);
  93 
  94   return closure.found();
  95 WB_END
  96 
  97 WB_ENTRY(void, WB_PrintHeapSizes(JNIEnv* env, jobject o)) {
  98   CollectorPolicy * p = Universe::heap()->collector_policy();
  99   gclog_or_tty->print_cr("Minimum heap "SIZE_FORMAT" Initial heap "
 100     SIZE_FORMAT" Maximum heap "SIZE_FORMAT" Min alignment "SIZE_FORMAT" Max alignment "SIZE_FORMAT,
 101     p->min_heap_byte_size(), p->initial_heap_byte_size(), p->max_heap_byte_size(),
 102     p->min_alignment(), p->max_alignment());
 103 }
 104 WB_END
 105 
 106 #if INCLUDE_ALL_GCS
 107 WB_ENTRY(jboolean, WB_G1IsHumongous(JNIEnv* env, jobject o, jobject obj))
 108   G1CollectedHeap* g1 = G1CollectedHeap::heap();
 109   oop result = JNIHandles::resolve(obj);
 110   const HeapRegion* hr = g1->heap_region_containing(result);
 111   return hr->isHumongous();
 112 WB_END
 113 
 114 WB_ENTRY(jlong, WB_G1NumFreeRegions(JNIEnv* env, jobject o))
 115   G1CollectedHeap* g1 = G1CollectedHeap::heap();
 116   size_t nr = g1->free_regions();
 117   return (jlong)nr;
 118 WB_END
 119 
 120 WB_ENTRY(jboolean, WB_G1InConcurrentMark(JNIEnv* env, jobject o))
 121   G1CollectedHeap* g1 = G1CollectedHeap::heap();
 122   ConcurrentMark* cm = g1->concurrent_mark();
 123   return cm->concurrent_marking_in_progress();
 124 WB_END
 125 
 126 WB_ENTRY(jint, WB_G1RegionSize(JNIEnv* env, jobject o))
 127   return (jint)HeapRegion::GrainBytes;
 128 WB_END
 129 #endif // INCLUDE_ALL_GCS
 130 
 131 #ifdef INCLUDE_NMT
 132 // Alloc memory using the test memory type so that we can use that to see if
 133 // NMT picks it up correctly
 134 WB_ENTRY(jlong, WB_NMTMalloc(JNIEnv* env, jobject o, jlong size))
 135   jlong addr = 0;
 136 
 137   if (MemTracker::is_on() && !MemTracker::shutdown_in_progress()) {
 138     addr = (jlong)(uintptr_t)os::malloc(size, mtTest);
 139   }
 140 
 141   return addr;
 142 WB_END
 143 
 144 // Free the memory allocated by NMTAllocTest
 145 WB_ENTRY(void, WB_NMTFree(JNIEnv* env, jobject o, jlong mem))
 146   os::free((void*)(uintptr_t)mem, mtTest);
 147 WB_END
 148 
 149 WB_ENTRY(jlong, WB_NMTReserveMemory(JNIEnv* env, jobject o, jlong size))
 150   jlong addr = 0;
 151 
 152   if (MemTracker::is_on() && !MemTracker::shutdown_in_progress()) {
 153     addr = (jlong)(uintptr_t)os::reserve_memory(size);
 154     MemTracker::record_virtual_memory_type((address)addr, mtTest);
 155   }
 156 
 157   return addr;
 158 WB_END
 159 
 160 
 161 WB_ENTRY(void, WB_NMTCommitMemory(JNIEnv* env, jobject o, jlong addr, jlong size))
 162   os::commit_memory((char *)(uintptr_t)addr, size, !ExecMem);
 163   MemTracker::record_virtual_memory_type((address)(uintptr_t)addr, mtTest);
 164 WB_END
 165 
 166 WB_ENTRY(void, WB_NMTUncommitMemory(JNIEnv* env, jobject o, jlong addr, jlong size))
 167   os::uncommit_memory((char *)(uintptr_t)addr, size);
 168 WB_END
 169 
 170 WB_ENTRY(void, WB_NMTReleaseMemory(JNIEnv* env, jobject o, jlong addr, jlong size))
 171   os::release_memory((char *)(uintptr_t)addr, size);
 172 WB_END
 173 
 174 // Block until the current generation of NMT data to be merged, used to reliably test the NMT feature
 175 WB_ENTRY(jboolean, WB_NMTWaitForDataMerge(JNIEnv* env))
 176 
 177   if (!MemTracker::is_on() || MemTracker::shutdown_in_progress()) {
 178     return false;
 179   }
 180 
 181   return MemTracker::wbtest_wait_for_data_merge();
 182 WB_END
 183 
 184 #endif // INCLUDE_NMT
 185 
 186 static jmethodID reflected_method_to_jmid(JavaThread* thread, JNIEnv* env, jobject method) {
 187   assert(method != NULL, "method should not be null");
 188   ThreadToNativeFromVM ttn(thread);
 189   return env->FromReflectedMethod(method);
 190 }
 191 
 192 WB_ENTRY(void, WB_DeoptimizeAll(JNIEnv* env, jobject o))
 193   MutexLockerEx mu(Compile_lock);
 194   CodeCache::mark_all_nmethods_for_deoptimization();
 195   VM_Deoptimize op;
 196   VMThread::execute(&op);
 197 WB_END
 198 
 199 WB_ENTRY(jint, WB_DeoptimizeMethod(JNIEnv* env, jobject o, jobject method, jboolean is_osr))
 200   jmethodID jmid = reflected_method_to_jmid(thread, env, method);
 201   MutexLockerEx mu(Compile_lock);
 202   methodHandle mh(THREAD, Method::checked_resolve_jmethod_id(jmid));
 203   int result = 0;
 204   nmethod* code;
 205   if (is_osr) {
 206     int bci = InvocationEntryBci;
 207     while ((code = mh->lookup_osr_nmethod_for(bci, CompLevel_none, false)) != NULL) {
 208       code->mark_for_deoptimization();
 209       ++result;
 210       bci = code->osr_entry_bci() + 1;
 211     }
 212   } else {
 213     code = mh->code();
 214   }
 215   if (code != NULL) {
 216     code->mark_for_deoptimization();
 217     ++result;
 218   }
 219   result += CodeCache::mark_for_deoptimization(mh());
 220   if (result > 0) {
 221     VM_Deoptimize op;
 222     VMThread::execute(&op);
 223   }
 224   return result;
 225 WB_END
 226 
 227 WB_ENTRY(jboolean, WB_IsMethodCompiled(JNIEnv* env, jobject o, jobject method, jboolean is_osr))
 228   jmethodID jmid = reflected_method_to_jmid(thread, env, method);
 229   MutexLockerEx mu(Compile_lock);
 230   methodHandle mh(THREAD, Method::checked_resolve_jmethod_id(jmid));
 231   nmethod* code = is_osr ? mh->lookup_osr_nmethod_for(InvocationEntryBci, CompLevel_none, false) : mh->code();
 232   if (code == NULL) {
 233     return JNI_FALSE;
 234   }
 235   return (code->is_alive() && !code->is_marked_for_deoptimization());
 236 WB_END
 237 
 238 WB_ENTRY(jboolean, WB_IsMethodCompilable(JNIEnv* env, jobject o, jobject method, jint comp_level, jboolean is_osr))
 239   jmethodID jmid = reflected_method_to_jmid(thread, env, method);
 240   MutexLockerEx mu(Compile_lock);
 241   methodHandle mh(THREAD, Method::checked_resolve_jmethod_id(jmid));
 242   if (is_osr) {
 243     return CompilationPolicy::can_be_osr_compiled(mh, comp_level);
 244   } else {
 245     return CompilationPolicy::can_be_compiled(mh, comp_level);
 246   }
 247 WB_END
 248 
 249 WB_ENTRY(jboolean, WB_IsMethodQueuedForCompilation(JNIEnv* env, jobject o, jobject method))
 250   jmethodID jmid = reflected_method_to_jmid(thread, env, method);
 251   MutexLockerEx mu(Compile_lock);
 252   methodHandle mh(THREAD, Method::checked_resolve_jmethod_id(jmid));
 253   return mh->queued_for_compilation();
 254 WB_END
 255 
 256 WB_ENTRY(jint, WB_GetMethodCompilationLevel(JNIEnv* env, jobject o, jobject method, jboolean is_osr))
 257   jmethodID jmid = reflected_method_to_jmid(thread, env, method);
 258   methodHandle mh(THREAD, Method::checked_resolve_jmethod_id(jmid));
 259   nmethod* code = is_osr ? mh->lookup_osr_nmethod_for(InvocationEntryBci, CompLevel_none, false) : mh->code();
 260   return (code != NULL ? code->comp_level() : CompLevel_none);
 261 WB_END
 262 
 263 WB_ENTRY(void, WB_MakeMethodNotCompilable(JNIEnv* env, jobject o, jobject method, jint comp_level, jboolean is_osr))
 264   jmethodID jmid = reflected_method_to_jmid(thread, env, method);
 265   methodHandle mh(THREAD, Method::checked_resolve_jmethod_id(jmid));
 266   if (is_osr) {
 267     mh->set_not_osr_compilable(comp_level, true /* report */, "WhiteBox");
 268   } else {
 269     mh->set_not_compilable(comp_level, true /* report */, "WhiteBox");
 270   }
 271 WB_END
 272 
 273 WB_ENTRY(jint, WB_GetMethodEntryBci(JNIEnv* env, jobject o, jobject method))
 274   jmethodID jmid = reflected_method_to_jmid(thread, env, method);
 275   methodHandle mh(THREAD, Method::checked_resolve_jmethod_id(jmid));
 276   nmethod* code = mh->lookup_osr_nmethod_for(InvocationEntryBci, CompLevel_none, false);
 277   return (code != NULL && code->is_osr_method() ? code->osr_entry_bci() : InvocationEntryBci);
 278 WB_END
 279 
 280 WB_ENTRY(jboolean, WB_TestSetDontInlineMethod(JNIEnv* env, jobject o, jobject method, jboolean value))
 281   jmethodID jmid = reflected_method_to_jmid(thread, env, method);
 282   methodHandle mh(THREAD, Method::checked_resolve_jmethod_id(jmid));
 283   bool result = mh->dont_inline();
 284   mh->set_dont_inline(value == JNI_TRUE);
 285   return result;
 286 WB_END
 287 
 288 WB_ENTRY(jint, WB_GetCompileQueueSize(JNIEnv* env, jobject o, jint comp_level))
 289   if (comp_level == CompLevel_any) {
 290     return CompileBroker::queue_size(CompLevel_full_optimization) /* C2 */ +
 291         CompileBroker::queue_size(CompLevel_full_profile) /* C1 */;
 292   } else {
 293     return CompileBroker::queue_size(comp_level);
 294   }
 295 WB_END
 296 
 297 WB_ENTRY(jboolean, WB_TestSetForceInlineMethod(JNIEnv* env, jobject o, jobject method, jboolean value))
 298   jmethodID jmid = reflected_method_to_jmid(thread, env, method);
 299   methodHandle mh(THREAD, Method::checked_resolve_jmethod_id(jmid));
 300   bool result = mh->force_inline();
 301   mh->set_force_inline(value == JNI_TRUE);
 302   return result;
 303 WB_END
 304 
 305 WB_ENTRY(jboolean, WB_EnqueueMethodForCompilation(JNIEnv* env, jobject o, jobject method, jint comp_level, jint bci))
 306   jmethodID jmid = reflected_method_to_jmid(thread, env, method);
 307   methodHandle mh(THREAD, Method::checked_resolve_jmethod_id(jmid));
 308   nmethod* nm = CompileBroker::compile_method(mh, bci, comp_level, mh, mh->invocation_count(), "WhiteBox", THREAD);
 309   MutexLockerEx mu(Compile_lock);
 310   return (mh->queued_for_compilation() || nm != NULL);
 311 WB_END
 312 
 313 WB_ENTRY(void, WB_ClearMethodState(JNIEnv* env, jobject o, jobject method))
 314   jmethodID jmid = reflected_method_to_jmid(thread, env, method);
 315   methodHandle mh(THREAD, Method::checked_resolve_jmethod_id(jmid));
 316   MutexLockerEx mu(Compile_lock);
 317   MethodData* mdo = mh->method_data();
 318   MethodCounters* mcs = mh->method_counters();
 319 
 320   if (mdo != NULL) {
 321     mdo->init();
 322     ResourceMark rm;
 323     int arg_count = mdo->method()->size_of_parameters();
 324     for (int i = 0; i < arg_count; i++) {
 325       mdo->set_arg_modified(i, 0);
 326     }
 327   }
 328 
 329   mh->clear_not_c1_compilable();
 330   mh->clear_not_c2_compilable();
 331   mh->clear_not_c2_osr_compilable();
 332   NOT_PRODUCT(mh->set_compiled_invocation_count(0));
 333   if (mcs != NULL) {
 334     mcs->backedge_counter()->init();
 335     mcs->invocation_counter()->init();
 336     mcs->set_interpreter_invocation_count(0);
 337     mcs->set_interpreter_throwout_count(0);
 338 
 339 #ifdef TIERED
 340     mcs->set_rate(0.0F);
 341     mh->set_prev_event_count(0, THREAD);
 342     mh->set_prev_time(0, THREAD);
 343 #endif
 344   }
 345 WB_END
 346 
 347 WB_ENTRY(jboolean, WB_IsInStringTable(JNIEnv* env, jobject o, jstring javaString))
 348   ResourceMark rm(THREAD);
 349   int len;
 350   jchar* name = java_lang_String::as_unicode_string(JNIHandles::resolve(javaString), len, CHECK_false);
 351   return (StringTable::lookup(name, len) != NULL);
 352 WB_END
 353 
 354 WB_ENTRY(void, WB_FullGC(JNIEnv* env, jobject o))
 355   Universe::heap()->collector_policy()->set_should_clear_all_soft_refs(true);
 356   Universe::heap()->collect(GCCause::_last_ditch_collection);
 357 WB_END
 358 
 359 
 360 WB_ENTRY(void, WB_ReadReservedMemory(JNIEnv* env, jobject o))
 361   // static+volatile in order to force the read to happen
 362   // (not be eliminated by the compiler)
 363   static char c;
 364   static volatile char* p;
 365 
 366   p = os::reserve_memory(os::vm_allocation_granularity(), NULL, 0);
 367   if (p == NULL) {
 368     THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), "Failed to reserve memory");
 369   }
 370 
 371   c = *p;
 372 WB_END
 373 
 374 //Some convenience methods to deal with objects from java
 375 int WhiteBox::offset_for_field(const char* field_name, oop object,
 376     Symbol* signature_symbol) {
 377   assert(field_name != NULL && strlen(field_name) > 0, "Field name not valid");
 378   Thread* THREAD = Thread::current();
 379 
 380   //Get the class of our object
 381   Klass* arg_klass = object->klass();
 382   //Turn it into an instance-klass
 383   InstanceKlass* ik = InstanceKlass::cast(arg_klass);
 384 
 385   //Create symbols to look for in the class
 386   TempNewSymbol name_symbol = SymbolTable::lookup(field_name, (int) strlen(field_name),
 387       THREAD);
 388 
 389   //To be filled in with an offset of the field we're looking for
 390   fieldDescriptor fd;
 391 
 392   Klass* res = ik->find_field(name_symbol, signature_symbol, &fd);
 393   if (res == NULL) {
 394     tty->print_cr("Invalid layout of %s at %s", ik->external_name(),
 395         name_symbol->as_C_string());
 396     fatal("Invalid layout of preloaded class");
 397   }
 398 
 399   //fetch the field at the offset we've found
 400   int dest_offset = fd.offset();
 401 
 402   return dest_offset;
 403 }
 404 
 405 
 406 const char* WhiteBox::lookup_jstring(const char* field_name, oop object) {
 407   int offset = offset_for_field(field_name, object,
 408       vmSymbols::string_signature());
 409   oop string = object->obj_field(offset);
 410   if (string == NULL) {
 411     return NULL;
 412   }
 413   const char* ret = java_lang_String::as_utf8_string(string);
 414   return ret;
 415 }
 416 
 417 bool WhiteBox::lookup_bool(const char* field_name, oop object) {
 418   int offset =
 419       offset_for_field(field_name, object, vmSymbols::bool_signature());
 420   bool ret = (object->bool_field(offset) == JNI_TRUE);
 421   return ret;
 422 }
 423 
 424 
 425 #define CC (char*)
 426 
 427 static JNINativeMethod methods[] = {
 428   {CC"getObjectAddress",   CC"(Ljava/lang/Object;)J", (void*)&WB_GetObjectAddress  },
 429   {CC"getHeapOopSize",     CC"()I",                   (void*)&WB_GetHeapOopSize    },
 430   {CC"isClassAlive0",      CC"(Ljava/lang/String;)Z", (void*)&WB_IsClassAlive      },
 431   {CC"parseCommandLine",
 432       CC"(Ljava/lang/String;[Lsun/hotspot/parser/DiagnosticCommand;)[Ljava/lang/Object;",
 433       (void*) &WB_ParseCommandLine
 434   },
 435   {CC"printHeapSizes",     CC"()V",                   (void*)&WB_PrintHeapSizes    },
 436 #if INCLUDE_ALL_GCS
 437   {CC"g1InConcurrentMark", CC"()Z",                   (void*)&WB_G1InConcurrentMark},
 438   {CC"g1IsHumongous",      CC"(Ljava/lang/Object;)Z", (void*)&WB_G1IsHumongous     },
 439   {CC"g1NumFreeRegions",   CC"()J",                   (void*)&WB_G1NumFreeRegions  },
 440   {CC"g1RegionSize",       CC"()I",                   (void*)&WB_G1RegionSize      },
 441 #endif // INCLUDE_ALL_GCS
 442 #ifdef INCLUDE_NMT
 443   {CC"NMTMalloc",           CC"(J)J",                 (void*)&WB_NMTMalloc          },
 444   {CC"NMTFree",             CC"(J)V",                 (void*)&WB_NMTFree            },
 445   {CC"NMTReserveMemory",    CC"(J)J",                 (void*)&WB_NMTReserveMemory   },
 446   {CC"NMTCommitMemory",     CC"(JJ)V",                (void*)&WB_NMTCommitMemory    },
 447   {CC"NMTUncommitMemory",   CC"(JJ)V",                (void*)&WB_NMTUncommitMemory  },
 448   {CC"NMTReleaseMemory",    CC"(JJ)V",                (void*)&WB_NMTReleaseMemory   },
 449   {CC"NMTWaitForDataMerge", CC"()Z",                  (void*)&WB_NMTWaitForDataMerge},
 450 #endif // INCLUDE_NMT
 451   {CC"deoptimizeAll",      CC"()V",                   (void*)&WB_DeoptimizeAll     },
 452   {CC"deoptimizeMethod",   CC"(Ljava/lang/reflect/Executable;Z)I",
 453                                                       (void*)&WB_DeoptimizeMethod  },
 454   {CC"isMethodCompiled",   CC"(Ljava/lang/reflect/Executable;Z)Z",
 455                                                       (void*)&WB_IsMethodCompiled  },
 456   {CC"isMethodCompilable", CC"(Ljava/lang/reflect/Executable;IZ)Z",
 457                                                       (void*)&WB_IsMethodCompilable},
 458   {CC"isMethodQueuedForCompilation",
 459       CC"(Ljava/lang/reflect/Executable;)Z",          (void*)&WB_IsMethodQueuedForCompilation},
 460   {CC"makeMethodNotCompilable",
 461       CC"(Ljava/lang/reflect/Executable;IZ)V",        (void*)&WB_MakeMethodNotCompilable},
 462   {CC"testSetDontInlineMethod",
 463       CC"(Ljava/lang/reflect/Executable;Z)Z",         (void*)&WB_TestSetDontInlineMethod},
 464   {CC"getMethodCompilationLevel",
 465       CC"(Ljava/lang/reflect/Executable;Z)I",         (void*)&WB_GetMethodCompilationLevel},
 466   {CC"getMethodEntryBci",
 467       CC"(Ljava/lang/reflect/Executable;)I",          (void*)&WB_GetMethodEntryBci},
 468   {CC"getCompileQueueSize",
 469       CC"(I)I",                                       (void*)&WB_GetCompileQueueSize},
 470   {CC"testSetForceInlineMethod",
 471       CC"(Ljava/lang/reflect/Executable;Z)Z",         (void*)&WB_TestSetForceInlineMethod},
 472   {CC"enqueueMethodForCompilation",
 473       CC"(Ljava/lang/reflect/Executable;II)Z",        (void*)&WB_EnqueueMethodForCompilation},
 474   {CC"clearMethodState",
 475       CC"(Ljava/lang/reflect/Executable;)V",          (void*)&WB_ClearMethodState},
 476   {CC"isInStringTable",   CC"(Ljava/lang/String;)Z",  (void*)&WB_IsInStringTable  },
 477   {CC"fullGC",   CC"()V",                             (void*)&WB_FullGC },
 478   {CC"readReservedMemory", CC"()V",                   (void*)&WB_ReadReservedMemory },
 479 };
 480 
 481 #undef CC
 482 
 483 JVM_ENTRY(void, JVM_RegisterWhiteBoxMethods(JNIEnv* env, jclass wbclass))
 484   {
 485     if (WhiteBoxAPI) {
 486       // Make sure that wbclass is loaded by the null classloader
 487       instanceKlassHandle ikh = instanceKlassHandle(JNIHandles::resolve(wbclass)->klass());
 488       Handle loader(ikh->class_loader());
 489       if (loader.is_null()) {
 490         ResourceMark rm;
 491         ThreadToNativeFromVM ttnfv(thread); // can't be in VM when we call JNI
 492         bool result = true;
 493         //  one by one registration natives for exception catching
 494         jclass exceptionKlass = env->FindClass(vmSymbols::java_lang_NoSuchMethodError()->as_C_string());
 495         for (int i = 0, n = sizeof(methods) / sizeof(methods[0]); i < n; ++i) {
 496           if (env->RegisterNatives(wbclass, methods + i, 1) != 0) {
 497             result = false;
 498             if (env->ExceptionCheck() && env->IsInstanceOf(env->ExceptionOccurred(), exceptionKlass)) {
 499               // j.l.NoSuchMethodError is thrown when a method can't be found or a method is not native
 500               // ignoring the exception
 501               tty->print_cr("Warning: 'NoSuchMethodError' on register of sun.hotspot.WhiteBox::%s%s", methods[i].name, methods[i].signature);
 502               env->ExceptionClear();
 503             } else {
 504               // register is failed w/o exception or w/ unexpected exception
 505               tty->print_cr("Warning: unexpected error on register of sun.hotspot.WhiteBox::%s%s. All methods will be unregistered", methods[i].name, methods[i].signature);
 506               env->UnregisterNatives(wbclass);
 507               break;
 508             }
 509           }
 510         }
 511 
 512         if (result) {
 513           WhiteBox::set_used();
 514         }
 515       }
 516     }
 517   }
 518 JVM_END