1 /*
2 * Copyright (c) 1998, 2010, 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 #ifndef _JAVA_JVMTIEXPORT_H_
26 #define _JAVA_JVMTIEXPORT_H_
27
28 // Forward declarations
29
30 class JvmtiEventControllerPrivate;
31 class JvmtiManageCapabilities;
32 class JvmtiEnv;
33 class JvmtiThreadState;
34 class AttachOperation;
35
36 #ifndef JVMTI_KERNEL
37 #define JVMTI_SUPPORT_FLAG(key) \
38 private: \
39 static bool _##key; \
40 public: \
41 inline static void set_##key(bool on) { _##key = (on != 0); } \
42 inline static bool key() { return _##key; }
43 #else // JVMTI_KERNEL
44 #define JVMTI_SUPPORT_FLAG(key) \
45 private: \
46 const static bool _##key = false; \
47 public: \
48 inline static void set_##key(bool on) { report_unsupported(on); } \
49 inline static bool key() { return _##key; }
50 #endif // JVMTI_KERNEL
51
52
53 // This class contains the JVMTI interface for the rest of hotspot.
54 //
55 class JvmtiExport : public AllStatic {
56 private:
57 static int _field_access_count;
58 static int _field_modification_count;
59
60 static bool _can_access_local_variables;
61 static bool _can_hotswap_or_post_breakpoint;
62 static bool _can_modify_any_class;
63 static bool _can_walk_any_space;
64
65 JVMTI_SUPPORT_FLAG(can_get_source_debug_extension)
66 JVMTI_SUPPORT_FLAG(can_maintain_original_method_order)
67 JVMTI_SUPPORT_FLAG(can_post_interpreter_events)
68 JVMTI_SUPPORT_FLAG(can_post_on_exceptions)
69 JVMTI_SUPPORT_FLAG(can_post_breakpoint)
70 JVMTI_SUPPORT_FLAG(can_post_field_access)
71 JVMTI_SUPPORT_FLAG(can_post_field_modification)
72 JVMTI_SUPPORT_FLAG(can_post_method_entry)
73 JVMTI_SUPPORT_FLAG(can_post_method_exit)
74 JVMTI_SUPPORT_FLAG(can_pop_frame)
75 JVMTI_SUPPORT_FLAG(can_force_early_return)
76
77 friend class JvmtiEventControllerPrivate; // should only modify these flags
78 JVMTI_SUPPORT_FLAG(should_post_single_step)
79 JVMTI_SUPPORT_FLAG(should_post_field_access)
80 JVMTI_SUPPORT_FLAG(should_post_field_modification)
81 JVMTI_SUPPORT_FLAG(should_post_class_load)
82 JVMTI_SUPPORT_FLAG(should_post_class_prepare)
83 JVMTI_SUPPORT_FLAG(should_post_class_unload)
84 JVMTI_SUPPORT_FLAG(should_post_native_method_bind)
85 JVMTI_SUPPORT_FLAG(should_post_compiled_method_load)
86 JVMTI_SUPPORT_FLAG(should_post_compiled_method_unload)
87 JVMTI_SUPPORT_FLAG(should_post_dynamic_code_generated)
88 JVMTI_SUPPORT_FLAG(should_post_monitor_contended_enter)
89 JVMTI_SUPPORT_FLAG(should_post_monitor_contended_entered)
90 JVMTI_SUPPORT_FLAG(should_post_monitor_wait)
91 JVMTI_SUPPORT_FLAG(should_post_monitor_waited)
92 JVMTI_SUPPORT_FLAG(should_post_data_dump)
93 JVMTI_SUPPORT_FLAG(should_post_garbage_collection_start)
94 JVMTI_SUPPORT_FLAG(should_post_garbage_collection_finish)
95 JVMTI_SUPPORT_FLAG(should_post_on_exceptions)
96
97 // ------ the below maybe don't have to be (but are for now)
98 // fixed conditions here ------------
99 // any events can be enabled
100 JVMTI_SUPPORT_FLAG(should_post_thread_life)
101 JVMTI_SUPPORT_FLAG(should_post_object_free)
102 JVMTI_SUPPORT_FLAG(should_post_resource_exhausted)
103
104 // we are holding objects on the heap - need to talk to GC - e.g.
105 // breakpoint info
106 JVMTI_SUPPORT_FLAG(should_clean_up_heap_objects)
107 JVMTI_SUPPORT_FLAG(should_post_vm_object_alloc)
108
109 // If flag cannot be implemented, give an error if on=true
110 static void report_unsupported(bool on);
111
112 // these should only be called by the friend class
113 friend class JvmtiManageCapabilities;
114 inline static void set_can_modify_any_class(bool on) { _can_modify_any_class = (on != 0); }
115 inline static void set_can_access_local_variables(bool on) { _can_access_local_variables = (on != 0); }
116 inline static void set_can_hotswap_or_post_breakpoint(bool on) { _can_hotswap_or_post_breakpoint = (on != 0); }
117 inline static void set_can_walk_any_space(bool on) { _can_walk_any_space = (on != 0); }
118
119 enum {
120 JVMTI_VERSION_MASK = 0x70000000,
121 JVMTI_VERSION_VALUE = 0x30000000,
122 JVMDI_VERSION_VALUE = 0x20000000
123 };
124
125 static void post_field_modification(JavaThread *thread, methodOop method, address location,
126 KlassHandle field_klass, Handle object, jfieldID field,
127 char sig_type, jvalue *value);
128
129
130 private:
131 // CompiledMethodUnload events are reported from the VM thread so they
132 // are collected in lists (of jmethodID/addresses) and the events are posted later
133 // from threads posting CompieldMethodLoad or DynamicCodeGenerated events.
134 static bool _have_pending_compiled_method_unload_events;
135 static GrowableArray<jmethodID>* _pending_compiled_method_unload_method_ids;
136 static GrowableArray<const void *>* _pending_compiled_method_unload_code_begins;
137 static JavaThread* _current_poster;
138
139 // tests if there are CompiledMethodUnload events pending
140 inline static bool have_pending_compiled_method_unload_events() {
141 return _have_pending_compiled_method_unload_events;
142 }
143
144 // posts any pending CompiledMethodUnload events.
145 static void post_pending_compiled_method_unload_events();
146
147 // Perform the actual notification to interested JvmtiEnvs.
148 static void post_compiled_method_unload_internal(JavaThread* self, jmethodID mid, const void* code_begin);
149
150 // posts a DynamicCodeGenerated event (internal/private implementation).
151 // The public post_dynamic_code_generated* functions make use of the
152 // internal implementation.
153 static void post_dynamic_code_generated_internal(const char *name, const void *code_begin, const void *code_end) KERNEL_RETURN;
154
155
156 // GenerateEvents support to allow posting of CompiledMethodLoad and
157 // DynamicCodeGenerated events for a given environment.
158 friend class JvmtiCodeBlobEvents;
159
160 static void post_compiled_method_load(JvmtiEnv* env, const jmethodID method, const jint length,
161 const void *code_begin, const jint map_length,
162 const jvmtiAddrLocationMap* map) KERNEL_RETURN;
163 static void post_dynamic_code_generated(JvmtiEnv* env, const char *name, const void *code_begin,
164 const void *code_end) KERNEL_RETURN;
165
166 // The RedefineClasses() API breaks some invariants in the "regular"
167 // system. For example, there are sanity checks when GC'ing nmethods
168 // that require the containing class to be unloading. However, when a
169 // method is redefined, the old method and nmethod can become GC'able
170 // without the containing class unloading. The state of becoming
171 // GC'able can be asynchronous to the RedefineClasses() call since
172 // the old method may still be running and cannot be GC'ed until
173 // after all old invocations have finished. Additionally, a method
174 // that has not been redefined may have an nmethod that depends on
175 // the redefined method. The dependent nmethod will get deopted in
176 // this case and may also be GC'able without the containing class
177 // being unloaded.
178 //
179 // This flag indicates whether RedefineClasses() has ever redefined
180 // one or more classes during the lifetime of the VM. The flag should
181 // only be set by the friend class and can be queried by other sub
182 // systems as needed to relax invariant checks.
183 static bool _has_redefined_a_class;
184 friend class VM_RedefineClasses;
185 inline static void set_has_redefined_a_class() {
186 _has_redefined_a_class = true;
187 }
188
189 // Flag to indicate if the compiler has recorded all dependencies. When the
190 // can_redefine_classes capability is enabled in the OnLoad phase then the compiler
191 // records all dependencies from startup. However if the capability is first
192 // enabled some time later then the dependencies recorded by the compiler
193 // are incomplete. This flag is used by RedefineClasses to know if the
194 // dependency information is complete or not.
195 static bool _all_dependencies_are_recorded;
196
197 public:
198 inline static bool has_redefined_a_class() {
199 return _has_redefined_a_class;
200 }
201
202 inline static bool all_dependencies_are_recorded() {
203 return _all_dependencies_are_recorded;
204 }
205
206 inline static void set_all_dependencies_are_recorded(bool on) {
207 _all_dependencies_are_recorded = (on != 0);
208 }
209
210
211 // let JVMTI know that the JVM_OnLoad code is running
212 static void enter_onload_phase();
213
214 // let JVMTI know that the VM isn't up yet (and JVM_OnLoad code isn't running)
215 static void enter_primordial_phase();
216
217 // let JVMTI know that the VM isn't up yet but JNI is live
218 static void enter_start_phase();
219
220 // let JVMTI know that the VM is fully up and running now
221 static void enter_live_phase();
222
223 // ------ can_* conditions (below) are set at OnLoad and never changed ------------
224 inline static bool can_modify_any_class() { return _can_modify_any_class; }
225 inline static bool can_access_local_variables() { return _can_access_local_variables; }
226 inline static bool can_hotswap_or_post_breakpoint() { return _can_hotswap_or_post_breakpoint; }
227 inline static bool can_walk_any_space() { return _can_walk_any_space; }
228
229 // field access management
230 static address get_field_access_count_addr();
231
232 // field modification management
233 static address get_field_modification_count_addr();
234
235 // -----------------
236
237 static bool is_jvmti_version(jint version) { return (version & JVMTI_VERSION_MASK) == JVMTI_VERSION_VALUE; }
238 static bool is_jvmdi_version(jint version) { return (version & JVMTI_VERSION_MASK) == JVMDI_VERSION_VALUE; }
239 static jint get_jvmti_interface(JavaVM *jvm, void **penv, jint version);
240 static void decode_version_values(jint version, int * major, int * minor,
241 int * micro);
242
243 // single stepping management methods
244 static void at_single_stepping_point(JavaThread *thread, methodOop method, address location) KERNEL_RETURN;
245 static void expose_single_stepping(JavaThread *thread) KERNEL_RETURN;
246 static bool hide_single_stepping(JavaThread *thread) KERNEL_RETURN_(return false;);
247
248 // Methods that notify the debugger that something interesting has happened in the VM.
249 static void post_vm_start ();
250 static void post_vm_initialized ();
251 static void post_vm_death ();
252
253 static void post_single_step (JavaThread *thread, methodOop method, address location) KERNEL_RETURN;
254 static void post_raw_breakpoint (JavaThread *thread, methodOop method, address location) KERNEL_RETURN;
255
256 static void post_exception_throw (JavaThread *thread, methodOop method, address location, oop exception) KERNEL_RETURN;
257 static void notice_unwind_due_to_exception (JavaThread *thread, methodOop method, address location, oop exception, bool in_handler_frame) KERNEL_RETURN;
258
259 static oop jni_GetField_probe (JavaThread *thread, jobject jobj,
260 oop obj, klassOop klass, jfieldID fieldID, bool is_static)
261 KERNEL_RETURN_(return NULL;);
262 static oop jni_GetField_probe_nh (JavaThread *thread, jobject jobj,
263 oop obj, klassOop klass, jfieldID fieldID, bool is_static)
264 KERNEL_RETURN_(return NULL;);
265 static void post_field_access_by_jni (JavaThread *thread, oop obj,
266 klassOop klass, jfieldID fieldID, bool is_static) KERNEL_RETURN;
267 static void post_field_access (JavaThread *thread, methodOop method,
268 address location, KlassHandle field_klass, Handle object, jfieldID field) KERNEL_RETURN;
269 static oop jni_SetField_probe (JavaThread *thread, jobject jobj,
270 oop obj, klassOop klass, jfieldID fieldID, bool is_static, char sig_type,
271 jvalue *value) KERNEL_RETURN_(return NULL;);
272 static oop jni_SetField_probe_nh (JavaThread *thread, jobject jobj,
273 oop obj, klassOop klass, jfieldID fieldID, bool is_static, char sig_type,
274 jvalue *value) KERNEL_RETURN_(return NULL;);
275 static void post_field_modification_by_jni(JavaThread *thread, oop obj,
276 klassOop klass, jfieldID fieldID, bool is_static, char sig_type,
277 jvalue *value);
278 static void post_raw_field_modification(JavaThread *thread, methodOop method,
279 address location, KlassHandle field_klass, Handle object, jfieldID field,
280 char sig_type, jvalue *value) KERNEL_RETURN;
281
282 static void post_method_entry (JavaThread *thread, methodOop method, frame current_frame) KERNEL_RETURN;
283 static void post_method_exit (JavaThread *thread, methodOop method, frame current_frame) KERNEL_RETURN;
284
285 static void post_class_load (JavaThread *thread, klassOop klass) KERNEL_RETURN;
286 static void post_class_unload (klassOop klass) KERNEL_RETURN;
287 static void post_class_prepare (JavaThread *thread, klassOop klass) KERNEL_RETURN;
288
289 static void post_thread_start (JavaThread *thread) KERNEL_RETURN;
290 static void post_thread_end (JavaThread *thread) KERNEL_RETURN;
291
292 // Support for java.lang.instrument agent loading.
293 static bool _should_post_class_file_load_hook;
294 inline static void set_should_post_class_file_load_hook(bool on) { _should_post_class_file_load_hook = on; }
295 inline static bool should_post_class_file_load_hook() { return _should_post_class_file_load_hook; }
296 static void post_class_file_load_hook(symbolHandle h_name, Handle class_loader,
297 Handle h_protection_domain,
298 unsigned char **data_ptr, unsigned char **end_ptr,
299 unsigned char **cached_data_ptr,
300 jint *cached_length_ptr);
301 static void post_native_method_bind(methodOop method, address* function_ptr) KERNEL_RETURN;
302 static void post_compiled_method_load(nmethod *nm) KERNEL_RETURN;
303 static void post_dynamic_code_generated(const char *name, const void *code_begin, const void *code_end) KERNEL_RETURN;
304
305 // used to post a CompiledMethodUnload event
306 static void post_compiled_method_unload(jmethodID mid, const void *code_begin) KERNEL_RETURN;
307
308 // similiar to post_dynamic_code_generated except that it can be used to
309 // post a DynamicCodeGenerated event while holding locks in the VM. Any event
310 // posted using this function is recorded by the enclosing event collector
311 // -- JvmtiDynamicCodeEventCollector.
312 static void post_dynamic_code_generated_while_holding_locks(const char* name, address code_begin, address code_end) KERNEL_RETURN;
313
314 static void post_garbage_collection_finish() KERNEL_RETURN;
315 static void post_garbage_collection_start() KERNEL_RETURN;
316 static void post_data_dump() KERNEL_RETURN;
317 static void post_monitor_contended_enter(JavaThread *thread, ObjectMonitor *obj_mntr) KERNEL_RETURN;
318 static void post_monitor_contended_entered(JavaThread *thread, ObjectMonitor *obj_mntr) KERNEL_RETURN;
319 static void post_monitor_wait(JavaThread *thread, oop obj, jlong timeout) KERNEL_RETURN;
320 static void post_monitor_waited(JavaThread *thread, ObjectMonitor *obj_mntr, jboolean timed_out) KERNEL_RETURN;
321 static void post_object_free(JvmtiEnv* env, jlong tag) KERNEL_RETURN;
322 static void post_resource_exhausted(jint resource_exhausted_flags, const char* detail) KERNEL_RETURN;
323 static void record_vm_internal_object_allocation(oop object) KERNEL_RETURN;
324 // Post objects collected by vm_object_alloc_event_collector.
325 static void post_vm_object_alloc(JavaThread *thread, oop object) KERNEL_RETURN;
326 // Collects vm internal objects for later event posting.
327 inline static void vm_object_alloc_event_collector(oop object) {
328 if (should_post_vm_object_alloc()) {
329 record_vm_internal_object_allocation(object);
330 }
331 }
332
333 static void cleanup_thread (JavaThread* thread) KERNEL_RETURN;
334
335 static void oops_do(OopClosure* f) KERNEL_RETURN;
336
337 static void transition_pending_onload_raw_monitors() KERNEL_RETURN;
338
339 #ifndef SERVICES_KERNEL
340 // attach support
341 static jint load_agent_library(AttachOperation* op, outputStream* out);
342 #endif // SERVICES_KERNEL
343
344 // SetNativeMethodPrefix support
345 static char** get_all_native_method_prefixes(int* count_ptr);
346
347 // call after CMS has completed referencing processing
348 static void cms_ref_processing_epilogue() KERNEL_RETURN;
349 };
350
351 // Support class used by JvmtiDynamicCodeEventCollector and others. It
352 // describes a single code blob by name and address range.
353 class JvmtiCodeBlobDesc : public CHeapObj {
354 private:
355 char _name[64];
356 address _code_begin;
357 address _code_end;
358
359 public:
360 JvmtiCodeBlobDesc(const char *name, address code_begin, address code_end) {
361 assert(name != NULL, "all code blobs must be named");
362 strncpy(_name, name, sizeof(_name));
363 _name[sizeof(_name)-1] = '\0';
364 _code_begin = code_begin;
365 _code_end = code_end;
366 }
367 char* name() { return _name; }
368 address code_begin() { return _code_begin; }
369 address code_end() { return _code_end; }
370 };
371
372 // JvmtiEventCollector is a helper class to setup thread for
373 // event collection.
374 class JvmtiEventCollector : public StackObj {
375 private:
376 JvmtiEventCollector* _prev; // Save previous one to support nested event collector.
377
378 public:
379 void setup_jvmti_thread_state(); // Set this collector in current thread.
380 void unset_jvmti_thread_state(); // Reset previous collector in current thread.
381 virtual bool is_dynamic_code_event() { return false; }
382 virtual bool is_vm_object_alloc_event(){ return false; }
383 JvmtiEventCollector *get_prev() { return _prev; }
384 };
385
386 // A JvmtiDynamicCodeEventCollector is a helper class for the JvmtiExport
387 // interface. It collects "dynamic code generated" events that are posted
388 // while holding locks. When the event collector goes out of scope the
389 // events will be posted.
390 //
391 // Usage :-
392 //
393 // {
394 // JvmtiDynamicCodeEventCollector event_collector;
395 // :
396 // { MutexLocker ml(...)
397 // :
398 // JvmtiExport::post_dynamic_code_generated_while_holding_locks(...)
399 // }
400 // // event collector goes out of scope => post events to profiler.
401 // }
402
403 class JvmtiDynamicCodeEventCollector : public JvmtiEventCollector {
404 private:
405 GrowableArray<JvmtiCodeBlobDesc*>* _code_blobs; // collected code blob events
406
407 friend class JvmtiExport;
408 void register_stub(const char* name, address start, address end);
409
410 public:
411 JvmtiDynamicCodeEventCollector() KERNEL_RETURN;
412 ~JvmtiDynamicCodeEventCollector() KERNEL_RETURN;
413 bool is_dynamic_code_event() { return true; }
414
415 };
416
417 // Used to record vm internally allocated object oops and post
418 // vm object alloc event for objects visible to java world.
419 // Constructor enables JvmtiThreadState flag and all vm allocated
420 // objects are recorded in a growable array. When destructor is
421 // called the vm object alloc event is posted for each objects
422 // visible to java world.
423 // See jvm.cpp file for its usage.
424 //
425 class JvmtiVMObjectAllocEventCollector : public JvmtiEventCollector {
426 private:
427 GrowableArray<oop>* _allocated; // field to record vm internally allocated object oop.
428 bool _enable; // This flag is enabled in constructor and disabled
429 // in destructor before posting event. To avoid
430 // collection of objects allocated while running java code inside
431 // agent post_vm_object_alloc() event handler.
432
433 //GC support
434 void oops_do(OopClosure* f);
435
436 friend class JvmtiExport;
437 // Record vm allocated object oop.
438 inline void record_allocation(oop obj);
439
440 //GC support
441 static void oops_do_for_all_threads(OopClosure* f);
442
443 public:
444 JvmtiVMObjectAllocEventCollector() KERNEL_RETURN;
445 ~JvmtiVMObjectAllocEventCollector() KERNEL_RETURN;
446 bool is_vm_object_alloc_event() { return true; }
447
448 bool is_enabled() { return _enable; }
449 void set_enabled(bool on) { _enable = on; }
450 };
451
452
453
454 // Marker class to disable the posting of VMObjectAlloc events
455 // within its scope.
456 //
457 // Usage :-
458 //
459 // {
460 // NoJvmtiVMObjectAllocMark njm;
461 // :
462 // // VMObjAlloc event will not be posted
463 // JvmtiExport::vm_object_alloc_event_collector(obj);
464 // :
465 // }
466
467 class NoJvmtiVMObjectAllocMark : public StackObj {
468 private:
469 // enclosing collector if enabled, NULL otherwise
470 JvmtiVMObjectAllocEventCollector *_collector;
471
472 bool was_enabled() { return _collector != NULL; }
473
474 public:
475 NoJvmtiVMObjectAllocMark() KERNEL_RETURN;
476 ~NoJvmtiVMObjectAllocMark() KERNEL_RETURN;
477 };
478
479
480 // Base class for reporting GC events to JVMTI.
481 class JvmtiGCMarker : public StackObj {
482 private:
483 bool _full; // marks a "full" GC
484 unsigned int _invocation_count; // GC invocation count
485 protected:
486 JvmtiGCMarker(bool full) KERNEL_RETURN; // protected
487 ~JvmtiGCMarker() KERNEL_RETURN; // protected
488 };
489
490
491 // Support class used to report GC events to JVMTI. The class is stack
492 // allocated and should be placed in the doit() implementation of all
493 // vm operations that do a stop-the-world GC for failed allocation.
494 //
495 // Usage :-
496 //
497 // void VM_GenCollectForAllocation::doit() {
498 // JvmtiGCForAllocationMarker jgcm;
499 // :
500 // }
501 //
502 // If jvmti is not enabled the constructor and destructor is essentially
503 // a no-op (no overhead).
504 //
505 class JvmtiGCForAllocationMarker : public JvmtiGCMarker {
506 public:
507 JvmtiGCForAllocationMarker() : JvmtiGCMarker(false) {
508 }
509 };
510
511 // Support class used to report GC events to JVMTI. The class is stack
512 // allocated and should be placed in the doit() implementation of all
513 // vm operations that do a "full" stop-the-world GC. This class differs
514 // from JvmtiGCForAllocationMarker in that this class assumes that a
515 // "full" GC will happen.
516 //
517 // Usage :-
518 //
519 // void VM_GenCollectFull::doit() {
520 // JvmtiGCFullMarker jgcm;
521 // :
522 // }
523 //
524 class JvmtiGCFullMarker : public JvmtiGCMarker {
525 public:
526 JvmtiGCFullMarker() : JvmtiGCMarker(true) {
527 }
528 };
529
530
531 // JvmtiHideSingleStepping is a helper class for hiding
532 // internal single step events.
533 class JvmtiHideSingleStepping : public StackObj {
534 private:
535 bool _single_step_hidden;
536 JavaThread * _thread;
537
538 public:
539 JvmtiHideSingleStepping(JavaThread * thread) {
540 assert(thread != NULL, "sanity check");
541
542 _single_step_hidden = false;
543 _thread = thread;
544 if (JvmtiExport::should_post_single_step()) {
545 _single_step_hidden = JvmtiExport::hide_single_stepping(_thread);
546 }
547 }
548
549 ~JvmtiHideSingleStepping() {
550 if (_single_step_hidden) {
551 JvmtiExport::expose_single_stepping(_thread);
552 }
553 }
554 };
555
556 #endif /* _JAVA_JVMTIEXPORT_H_ */