1 /*
2 * Copyright (c) 1998, 2012, 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 SHARE_VM_PRIMS_JVMTIEXPORT_HPP
26 #define SHARE_VM_PRIMS_JVMTIEXPORT_HPP
27
28 #include "jvmtifiles/jvmti.h"
29 #include "memory/allocation.hpp"
30 #include "memory/iterator.hpp"
31 #include "oops/oop.hpp"
32 #include "oops/oopsHierarchy.hpp"
33 #include "runtime/frame.hpp"
34 #include "runtime/handles.hpp"
35 #include "utilities/globalDefinitions.hpp"
36 #include "utilities/growableArray.hpp"
37
38 // Must be included after jvmti.h.
39 #include "code/jvmticmlr.h"
40
41 // Forward declarations
42
43 class JvmtiEventControllerPrivate;
44 class JvmtiManageCapabilities;
45 class JvmtiEnv;
46 class JvmtiThreadState;
47 class AttachOperation;
48
49 #define JVMTI_SUPPORT_FLAG(key) \
50 private: \
51 static bool _##key; \
52 public: \
53 inline static void set_##key(bool on) { \
54 JVMTI_ONLY(_##key = (on != 0)); \
55 NOT_JVMTI(report_unsupported(on)); \
56 } \
57 inline static bool key() { \
58 JVMTI_ONLY(return _##key); \
59 NOT_JVMTI(return false); \
60 }
61
62
63 // This class contains the JVMTI interface for the rest of hotspot.
64 //
65 class JvmtiExport : public AllStatic {
66 friend class VMStructs;
67 private:
68
69 #if INCLUDE_JVMTI
70 static int _field_access_count;
71 static int _field_modification_count;
72
73 static bool _can_access_local_variables;
74 static bool _can_hotswap_or_post_breakpoint;
75 static bool _can_modify_any_class;
76 static bool _can_walk_any_space;
77 #endif // INCLUDE_JVMTI
78
79 JVMTI_SUPPORT_FLAG(can_get_source_debug_extension)
80 JVMTI_SUPPORT_FLAG(can_maintain_original_method_order)
81 JVMTI_SUPPORT_FLAG(can_post_interpreter_events)
82 JVMTI_SUPPORT_FLAG(can_post_on_exceptions)
83 JVMTI_SUPPORT_FLAG(can_post_breakpoint)
84 JVMTI_SUPPORT_FLAG(can_post_field_access)
85 JVMTI_SUPPORT_FLAG(can_post_field_modification)
86 JVMTI_SUPPORT_FLAG(can_post_method_entry)
87 JVMTI_SUPPORT_FLAG(can_post_method_exit)
88 JVMTI_SUPPORT_FLAG(can_pop_frame)
89 JVMTI_SUPPORT_FLAG(can_force_early_return)
90
91 friend class JvmtiEventControllerPrivate; // should only modify these flags
92 JVMTI_SUPPORT_FLAG(should_post_single_step)
93 JVMTI_SUPPORT_FLAG(should_post_field_access)
94 JVMTI_SUPPORT_FLAG(should_post_field_modification)
95 JVMTI_SUPPORT_FLAG(should_post_class_load)
96 JVMTI_SUPPORT_FLAG(should_post_class_prepare)
97 JVMTI_SUPPORT_FLAG(should_post_class_unload)
98 JVMTI_SUPPORT_FLAG(should_post_native_method_bind)
99 JVMTI_SUPPORT_FLAG(should_post_compiled_method_load)
100 JVMTI_SUPPORT_FLAG(should_post_compiled_method_unload)
101 JVMTI_SUPPORT_FLAG(should_post_dynamic_code_generated)
102 JVMTI_SUPPORT_FLAG(should_post_monitor_contended_enter)
103 JVMTI_SUPPORT_FLAG(should_post_monitor_contended_entered)
104 JVMTI_SUPPORT_FLAG(should_post_monitor_wait)
105 JVMTI_SUPPORT_FLAG(should_post_monitor_waited)
106 JVMTI_SUPPORT_FLAG(should_post_data_dump)
107 JVMTI_SUPPORT_FLAG(should_post_garbage_collection_start)
108 JVMTI_SUPPORT_FLAG(should_post_garbage_collection_finish)
109 JVMTI_SUPPORT_FLAG(should_post_on_exceptions)
110
111 // ------ the below maybe don't have to be (but are for now)
112 // fixed conditions here ------------
113 // any events can be enabled
114 JVMTI_SUPPORT_FLAG(should_post_thread_life)
115 JVMTI_SUPPORT_FLAG(should_post_object_free)
116 JVMTI_SUPPORT_FLAG(should_post_resource_exhausted)
117
118 // we are holding objects on the heap - need to talk to GC - e.g.
119 // breakpoint info
120 JVMTI_SUPPORT_FLAG(should_clean_up_heap_objects)
121 JVMTI_SUPPORT_FLAG(should_post_vm_object_alloc)
122
123 // If flag cannot be implemented, give an error if on=true
124 static void report_unsupported(bool on);
125
126 // these should only be called by the friend class
127 friend class JvmtiManageCapabilities;
128 inline static void set_can_modify_any_class(bool on) {
129 JVMTI_ONLY(_can_modify_any_class = (on != 0);)
130 }
131 inline static void set_can_access_local_variables(bool on) {
132 JVMTI_ONLY(_can_access_local_variables = (on != 0);)
133 }
134 inline static void set_can_hotswap_or_post_breakpoint(bool on) {
135 JVMTI_ONLY(_can_hotswap_or_post_breakpoint = (on != 0);)
136 }
137 inline static void set_can_walk_any_space(bool on) {
138 JVMTI_ONLY(_can_walk_any_space = (on != 0);)
139 }
140
141 enum {
142 JVMTI_VERSION_MASK = 0x70000000,
143 JVMTI_VERSION_VALUE = 0x30000000,
144 JVMDI_VERSION_VALUE = 0x20000000
145 };
146
147 static void post_field_modification(JavaThread *thread, Method* method, address location,
148 KlassHandle field_klass, Handle object, jfieldID field,
149 char sig_type, jvalue *value);
150
151
152 // posts a DynamicCodeGenerated event (internal/private implementation).
153 // The public post_dynamic_code_generated* functions make use of the
154 // internal implementation. Also called from JvmtiDeferredEvent::post()
155 static void post_dynamic_code_generated_internal(const char *name, const void *code_begin, const void *code_end) NOT_JVMTI_RETURN;
156
157 private:
158
159 // GenerateEvents support to allow posting of CompiledMethodLoad and
160 // DynamicCodeGenerated events for a given environment.
161 friend class JvmtiCodeBlobEvents;
162
163 static void post_compiled_method_load(JvmtiEnv* env, const jmethodID method, const jint length,
164 const void *code_begin, const jint map_length,
165 const jvmtiAddrLocationMap* map) NOT_JVMTI_RETURN;
166 static void post_dynamic_code_generated(JvmtiEnv* env, const char *name, const void *code_begin,
167 const void *code_end) NOT_JVMTI_RETURN;
168
169 // The RedefineClasses() API breaks some invariants in the "regular"
170 // system. For example, there are sanity checks when GC'ing nmethods
171 // that require the containing class to be unloading. However, when a
172 // method is redefined, the old method and nmethod can become GC'able
173 // without the containing class unloading. The state of becoming
174 // GC'able can be asynchronous to the RedefineClasses() call since
175 // the old method may still be running and cannot be GC'ed until
176 // after all old invocations have finished. Additionally, a method
177 // that has not been redefined may have an nmethod that depends on
178 // the redefined method. The dependent nmethod will get deopted in
179 // this case and may also be GC'able without the containing class
180 // being unloaded.
181 //
182 // This flag indicates whether RedefineClasses() has ever redefined
183 // one or more classes during the lifetime of the VM. The flag should
184 // only be set by the friend class and can be queried by other sub
185 // systems as needed to relax invariant checks.
186 static bool _has_redefined_a_class;
187 friend class VM_RedefineClasses;
188 inline static void set_has_redefined_a_class() {
189 JVMTI_ONLY(_has_redefined_a_class = true;)
190 }
191 // Flag to indicate if the compiler has recorded all dependencies. When the
192 // can_redefine_classes capability is enabled in the OnLoad phase then the compiler
193 // records all dependencies from startup. However if the capability is first
194 // enabled some time later then the dependencies recorded by the compiler
195 // are incomplete. This flag is used by RedefineClasses to know if the
196 // dependency information is complete or not.
197 static bool _all_dependencies_are_recorded;
198
199 public:
200 inline static bool has_redefined_a_class() {
201 JVMTI_ONLY(return _has_redefined_a_class);
202 NOT_JVMTI(return false);
203 }
204
205 inline static bool all_dependencies_are_recorded() {
206 return _all_dependencies_are_recorded;
207 }
208
209 inline static void set_all_dependencies_are_recorded(bool on) {
210 _all_dependencies_are_recorded = (on != 0);
211 }
212
213
214 // let JVMTI know that the JVM_OnLoad code is running
215 static void enter_onload_phase() NOT_JVMTI_RETURN;
216
217 // let JVMTI know that the VM isn't up yet (and JVM_OnLoad code isn't running)
218 static void enter_primordial_phase() NOT_JVMTI_RETURN;
219
220 // let JVMTI know that the VM isn't up yet but JNI is live
221 static void enter_start_phase() NOT_JVMTI_RETURN;
222
223 // let JVMTI know that the VM is fully up and running now
224 static void enter_live_phase() NOT_JVMTI_RETURN;
225
226 // ------ can_* conditions (below) are set at OnLoad and never changed ------------
227 inline static bool can_modify_any_class() {
228 JVMTI_ONLY(return _can_modify_any_class);
229 NOT_JVMTI(return false);
230 }
231 inline static bool can_access_local_variables() {
232 JVMTI_ONLY(return _can_access_local_variables);
233 NOT_JVMTI(return false);
234 }
235 inline static bool can_hotswap_or_post_breakpoint() {
236 JVMTI_ONLY(return _can_hotswap_or_post_breakpoint);
237 NOT_JVMTI(return false);
238 }
239 inline static bool can_walk_any_space() {
240 JVMTI_ONLY(return _can_walk_any_space);
241 NOT_JVMTI(return false);
242 }
243
244 // field access management
245 static address get_field_access_count_addr() NOT_JVMTI_RETURN_(0);
246
247 // field modification management
248 static address get_field_modification_count_addr() NOT_JVMTI_RETURN_(0);
249
250 // -----------------
251
252 static bool is_jvmti_version(jint version) {
253 JVMTI_ONLY(return (version & JVMTI_VERSION_MASK) == JVMTI_VERSION_VALUE);
254 NOT_JVMTI(return false);
255 }
256 static bool is_jvmdi_version(jint version) {
257 JVMTI_ONLY(return (version & JVMTI_VERSION_MASK) == JVMDI_VERSION_VALUE);
258 NOT_JVMTI(return false);
259 }
260 static jint get_jvmti_interface(JavaVM *jvm, void **penv, jint version) NOT_JVMTI_RETURN_(0);
261 static void decode_version_values(jint version, int * major, int * minor,
262 int * micro) NOT_JVMTI_RETURN;
263
264 // single stepping management methods
265 static void at_single_stepping_point(JavaThread *thread, Method* method, address location) NOT_JVMTI_RETURN;
266 static void expose_single_stepping(JavaThread *thread) NOT_JVMTI_RETURN;
267 static bool hide_single_stepping(JavaThread *thread) NOT_JVMTI_RETURN_(false);
268
269 // Methods that notify the debugger that something interesting has happened in the VM.
270 static void post_vm_start () NOT_JVMTI_RETURN;
271 static void post_vm_initialized () NOT_JVMTI_RETURN;
272 static void post_vm_death () NOT_JVMTI_RETURN;
273
274 static void post_single_step (JavaThread *thread, Method* method, address location) NOT_JVMTI_RETURN;
275 static void post_raw_breakpoint (JavaThread *thread, Method* method, address location) NOT_JVMTI_RETURN;
276
277 static void post_exception_throw (JavaThread *thread, Method* method, address location, oop exception) NOT_JVMTI_RETURN;
278 static void notice_unwind_due_to_exception (JavaThread *thread, Method* method, address location, oop exception, bool in_handler_frame) NOT_JVMTI_RETURN;
279
280 static oop jni_GetField_probe (JavaThread *thread, jobject jobj,
281 oop obj, Klass* klass, jfieldID fieldID, bool is_static)
282 NOT_JVMTI_RETURN_(NULL);
283 static oop jni_GetField_probe_nh (JavaThread *thread, jobject jobj,
284 oop obj, Klass* klass, jfieldID fieldID, bool is_static)
285 NOT_JVMTI_RETURN_(NULL);
286 static void post_field_access_by_jni (JavaThread *thread, oop obj,
287 Klass* klass, jfieldID fieldID, bool is_static) NOT_JVMTI_RETURN;
288 static void post_field_access (JavaThread *thread, Method* method,
289 address location, KlassHandle field_klass, Handle object, jfieldID field) NOT_JVMTI_RETURN;
290 static oop jni_SetField_probe (JavaThread *thread, jobject jobj,
291 oop obj, Klass* klass, jfieldID fieldID, bool is_static, char sig_type,
292 jvalue *value) NOT_JVMTI_RETURN_(NULL);
293 static oop jni_SetField_probe_nh (JavaThread *thread, jobject jobj,
294 oop obj, Klass* klass, jfieldID fieldID, bool is_static, char sig_type,
295 jvalue *value) NOT_JVMTI_RETURN_(NULL);
296 static void post_field_modification_by_jni(JavaThread *thread, oop obj,
297 Klass* klass, jfieldID fieldID, bool is_static, char sig_type,
298 jvalue *value);
299 static void post_raw_field_modification(JavaThread *thread, Method* method,
300 address location, KlassHandle field_klass, Handle object, jfieldID field,
301 char sig_type, jvalue *value) NOT_JVMTI_RETURN;
302
303 static void post_method_entry (JavaThread *thread, Method* method, frame current_frame) NOT_JVMTI_RETURN;
304 static void post_method_exit (JavaThread *thread, Method* method, frame current_frame) NOT_JVMTI_RETURN;
305
306 static void post_class_load (JavaThread *thread, Klass* klass) NOT_JVMTI_RETURN;
307 static void post_class_unload (Klass* klass) NOT_JVMTI_RETURN;
308 static void post_class_prepare (JavaThread *thread, Klass* klass) NOT_JVMTI_RETURN;
309
310 static void post_thread_start (JavaThread *thread) NOT_JVMTI_RETURN;
311 static void post_thread_end (JavaThread *thread) NOT_JVMTI_RETURN;
312
313 // Support for java.lang.instrument agent loading.
314 static bool _should_post_class_file_load_hook;
315 inline static void set_should_post_class_file_load_hook(bool on) { _should_post_class_file_load_hook = on; }
316 inline static bool should_post_class_file_load_hook() {
317 JVMTI_ONLY(return _should_post_class_file_load_hook);
318 NOT_JVMTI(return false;)
319 }
320 static void post_class_file_load_hook(Symbol* h_name, Handle class_loader,
321 Handle h_protection_domain,
322 unsigned char **data_ptr, unsigned char **end_ptr,
323 unsigned char **cached_data_ptr,
324 jint *cached_length_ptr) NOT_JVMTI_RETURN;
325 static void post_native_method_bind(Method* method, address* function_ptr) NOT_JVMTI_RETURN;
326 static void post_compiled_method_load(nmethod *nm) NOT_JVMTI_RETURN;
327 static void post_dynamic_code_generated(const char *name, const void *code_begin, const void *code_end) NOT_JVMTI_RETURN;
328
329 // used to post a CompiledMethodUnload event
330 static void post_compiled_method_unload(jmethodID mid, const void *code_begin) NOT_JVMTI_RETURN;
331
332 // similiar to post_dynamic_code_generated except that it can be used to
333 // post a DynamicCodeGenerated event while holding locks in the VM. Any event
334 // posted using this function is recorded by the enclosing event collector
335 // -- JvmtiDynamicCodeEventCollector.
336 static void post_dynamic_code_generated_while_holding_locks(const char* name, address code_begin, address code_end) NOT_JVMTI_RETURN;
337
338 static void post_garbage_collection_finish() NOT_JVMTI_RETURN;
339 static void post_garbage_collection_start() NOT_JVMTI_RETURN;
340 static void post_data_dump() NOT_JVMTI_RETURN;
341 static void post_monitor_contended_enter(JavaThread *thread, ObjectMonitor *obj_mntr) NOT_JVMTI_RETURN;
342 static void post_monitor_contended_entered(JavaThread *thread, ObjectMonitor *obj_mntr) NOT_JVMTI_RETURN;
343 static void post_monitor_wait(JavaThread *thread, oop obj, jlong timeout) NOT_JVMTI_RETURN;
344 static void post_monitor_waited(JavaThread *thread, ObjectMonitor *obj_mntr, jboolean timed_out) NOT_JVMTI_RETURN;
345 static void post_object_free(JvmtiEnv* env, jlong tag) NOT_JVMTI_RETURN;
346 static void post_resource_exhausted(jint resource_exhausted_flags, const char* detail) NOT_JVMTI_RETURN;
347 static void record_vm_internal_object_allocation(oop object) NOT_JVMTI_RETURN;
348 // Post objects collected by vm_object_alloc_event_collector.
349 static void post_vm_object_alloc(JavaThread *thread, oop object) NOT_JVMTI_RETURN;
350 // Collects vm internal objects for later event posting.
351 inline static void vm_object_alloc_event_collector(oop object) {
352 if (should_post_vm_object_alloc()) {
353 record_vm_internal_object_allocation(object);
354 }
355 }
356 inline static void post_array_size_exhausted() {
357 if (should_post_resource_exhausted()) {
358 post_resource_exhausted(JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR,
359 "Requested array size exceeds VM limit");
360 }
361 }
362
363 static void cleanup_thread (JavaThread* thread) NOT_JVMTI_RETURN;
364
365 static void oops_do(OopClosure* f) NOT_JVMTI_RETURN;
366 static void weak_oops_do(BoolObjectClosure* b, OopClosure* f) NOT_JVMTI_RETURN;
367 static void gc_epilogue() NOT_JVMTI_RETURN;
368
369 static void transition_pending_onload_raw_monitors() NOT_JVMTI_RETURN;
370
371 // attach support
372 static jint load_agent_library(AttachOperation* op, outputStream* out) NOT_JVMTI_RETURN_(JNI_ERR);
373
374 // SetNativeMethodPrefix support
375 static char** get_all_native_method_prefixes(int* count_ptr) NOT_JVMTI_RETURN_(NULL);
376 };
377
378 // Support class used by JvmtiDynamicCodeEventCollector and others. It
379 // describes a single code blob by name and address range.
380 class JvmtiCodeBlobDesc : public CHeapObj<mtInternal> {
381 private:
382 char _name[64];
383 address _code_begin;
384 address _code_end;
385
386 public:
387 JvmtiCodeBlobDesc(const char *name, address code_begin, address code_end) {
388 assert(name != NULL, "all code blobs must be named");
389 strncpy(_name, name, sizeof(_name));
390 _name[sizeof(_name)-1] = '\0';
391 _code_begin = code_begin;
392 _code_end = code_end;
393 }
394 char* name() { return _name; }
395 address code_begin() { return _code_begin; }
396 address code_end() { return _code_end; }
397 };
398
399 // JvmtiEventCollector is a helper class to setup thread for
400 // event collection.
401 class JvmtiEventCollector : public StackObj {
402 private:
403 JvmtiEventCollector* _prev; // Save previous one to support nested event collector.
404
405 public:
406 void setup_jvmti_thread_state(); // Set this collector in current thread.
407 void unset_jvmti_thread_state(); // Reset previous collector in current thread.
408 virtual bool is_dynamic_code_event() { return false; }
409 virtual bool is_vm_object_alloc_event(){ return false; }
410 JvmtiEventCollector *get_prev() { return _prev; }
411 };
412
413 // A JvmtiDynamicCodeEventCollector is a helper class for the JvmtiExport
414 // interface. It collects "dynamic code generated" events that are posted
415 // while holding locks. When the event collector goes out of scope the
416 // events will be posted.
417 //
418 // Usage :-
419 //
420 // {
421 // JvmtiDynamicCodeEventCollector event_collector;
422 // :
423 // { MutexLocker ml(...)
424 // :
425 // JvmtiExport::post_dynamic_code_generated_while_holding_locks(...)
426 // }
427 // // event collector goes out of scope => post events to profiler.
428 // }
429
430 class JvmtiDynamicCodeEventCollector : public JvmtiEventCollector {
431 private:
432 GrowableArray<JvmtiCodeBlobDesc*>* _code_blobs; // collected code blob events
433
434 friend class JvmtiExport;
435 void register_stub(const char* name, address start, address end);
436
437 public:
438 JvmtiDynamicCodeEventCollector() NOT_JVMTI_RETURN;
439 ~JvmtiDynamicCodeEventCollector() NOT_JVMTI_RETURN;
440 bool is_dynamic_code_event() { return true; }
441
442 };
443
444 // Used to record vm internally allocated object oops and post
445 // vm object alloc event for objects visible to java world.
446 // Constructor enables JvmtiThreadState flag and all vm allocated
447 // objects are recorded in a growable array. When destructor is
448 // called the vm object alloc event is posted for each objects
449 // visible to java world.
450 // See jvm.cpp file for its usage.
451 //
452 class JvmtiVMObjectAllocEventCollector : public JvmtiEventCollector {
453 private:
454 GrowableArray<oop>* _allocated; // field to record vm internally allocated object oop.
455 bool _enable; // This flag is enabled in constructor and disabled
456 // in destructor before posting event. To avoid
457 // collection of objects allocated while running java code inside
458 // agent post_vm_object_alloc() event handler.
459
460 //GC support
461 void oops_do(OopClosure* f);
462
463 friend class JvmtiExport;
464 // Record vm allocated object oop.
465 inline void record_allocation(oop obj);
466
467 //GC support
468 static void oops_do_for_all_threads(OopClosure* f);
469
470 public:
471 JvmtiVMObjectAllocEventCollector() NOT_JVMTI_RETURN;
472 ~JvmtiVMObjectAllocEventCollector() NOT_JVMTI_RETURN;
473 bool is_vm_object_alloc_event() { return true; }
474
475 bool is_enabled() { return _enable; }
476 void set_enabled(bool on) { _enable = on; }
477 };
478
479
480
481 // Marker class to disable the posting of VMObjectAlloc events
482 // within its scope.
483 //
484 // Usage :-
485 //
486 // {
487 // NoJvmtiVMObjectAllocMark njm;
488 // :
489 // // VMObjAlloc event will not be posted
490 // JvmtiExport::vm_object_alloc_event_collector(obj);
491 // :
492 // }
493
494 class NoJvmtiVMObjectAllocMark : public StackObj {
495 private:
496 // enclosing collector if enabled, NULL otherwise
497 JvmtiVMObjectAllocEventCollector *_collector;
498
499 bool was_enabled() { return _collector != NULL; }
500
501 public:
502 NoJvmtiVMObjectAllocMark() NOT_JVMTI_RETURN;
503 ~NoJvmtiVMObjectAllocMark() NOT_JVMTI_RETURN;
504 };
505
506
507 // Base class for reporting GC events to JVMTI.
508 class JvmtiGCMarker : public StackObj {
509 public:
510 JvmtiGCMarker() NOT_JVMTI_RETURN;
511 ~JvmtiGCMarker() NOT_JVMTI_RETURN;
512 };
513
514 // JvmtiHideSingleStepping is a helper class for hiding
515 // internal single step events.
516 class JvmtiHideSingleStepping : public StackObj {
517 private:
518 bool _single_step_hidden;
519 JavaThread * _thread;
520
521 public:
522 JvmtiHideSingleStepping(JavaThread * thread) {
523 assert(thread != NULL, "sanity check");
524
525 _single_step_hidden = false;
526 _thread = thread;
527 if (JvmtiExport::should_post_single_step()) {
528 _single_step_hidden = JvmtiExport::hide_single_stepping(_thread);
529 }
530 }
531
532 ~JvmtiHideSingleStepping() {
533 if (_single_step_hidden) {
534 JvmtiExport::expose_single_stepping(_thread);
535 }
536 }
537 };
538
539 #endif // SHARE_VM_PRIMS_JVMTIEXPORT_HPP