1/*
2 * Copyright (c) 2003, 2015, 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 "gc/shared/gcLocker.hpp"
27#include "jvmtifiles/jvmtiEnv.hpp"
28#include "memory/resourceArea.hpp"
29#include "prims/jvmtiEventController.inline.hpp"
30#include "prims/jvmtiImpl.hpp"
31#include "prims/jvmtiThreadState.inline.hpp"
32#include "runtime/vframe.hpp"
33
34// marker for when the stack depth has been reset and is now unknown.
35// any negative number would work but small ones might obscure an
36// underrun error.
37static const int UNKNOWN_STACK_DEPTH = -99;
38
39///////////////////////////////////////////////////////////////
40//
41// class JvmtiThreadState
42//
43// Instances of JvmtiThreadState hang off of each thread.
44// Thread local storage for JVMTI.
45//
46
47JvmtiThreadState *JvmtiThreadState::_head = NULL;
48
49JvmtiThreadState::JvmtiThreadState(JavaThread* thread)
50  : _thread_event_enable() {
51  assert(JvmtiThreadState_lock->is_locked(), "sanity check");
52  _thread               = thread;
53  _exception_state      = ES_CLEARED;
54  _debuggable           = true;
55  _hide_single_stepping = false;
56  _hide_level           = 0;
57  _pending_step_for_popframe = false;
58  _class_being_redefined = NULL;
59  _class_load_kind = jvmti_class_load_kind_load;
60  _head_env_thread_state = NULL;
61  _dynamic_code_event_collector = NULL;
62  _vm_object_alloc_event_collector = NULL;
63  _the_class_for_redefinition_verification = NULL;
64  _scratch_class_for_redefinition_verification = NULL;
65  _cur_stack_depth = UNKNOWN_STACK_DEPTH;
66
67  // JVMTI ForceEarlyReturn support
68  _pending_step_for_earlyret = false;
69  _earlyret_state = earlyret_inactive;
70  _earlyret_tos = ilgl;
71  _earlyret_value.j = 0L;
72  _earlyret_oop = NULL;
73
74  // add all the JvmtiEnvThreadState to the new JvmtiThreadState
75  {
76    JvmtiEnvIterator it;
77    for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
78      if (env->is_valid()) {
79        add_env(env);
80      }
81    }
82  }
83
84  // link us into the list
85  {
86    // The thread state list manipulation code must not have safepoints.
87    // See periodic_clean_up().
88    debug_only(NoSafepointVerifier nosafepoint;)
89
90    _prev = NULL;
91    _next = _head;
92    if (_head != NULL) {
93      _head->_prev = this;
94    }
95    _head = this;
96  }
97
98  // set this as the state for the thread
99  thread->set_jvmti_thread_state(this);
100}
101
102
103JvmtiThreadState::~JvmtiThreadState()   {
104  assert(JvmtiThreadState_lock->is_locked(), "sanity check");
105
106  // clear this as the state for the thread
107  get_thread()->set_jvmti_thread_state(NULL);
108
109  // zap our env thread states
110  {
111    JvmtiEnvBase::entering_dying_thread_env_iteration();
112    JvmtiEnvThreadStateIterator it(this);
113    for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ) {
114      JvmtiEnvThreadState* zap = ets;
115      ets = it.next(ets);
116      delete zap;
117    }
118    JvmtiEnvBase::leaving_dying_thread_env_iteration();
119  }
120
121  // remove us from the list
122  {
123    // The thread state list manipulation code must not have safepoints.
124    // See periodic_clean_up().
125    debug_only(NoSafepointVerifier nosafepoint;)
126
127    if (_prev == NULL) {
128      assert(_head == this, "sanity check");
129      _head = _next;
130    } else {
131      assert(_head != this, "sanity check");
132      _prev->_next = _next;
133    }
134    if (_next != NULL) {
135      _next->_prev = _prev;
136    }
137    _next = NULL;
138    _prev = NULL;
139  }
140}
141
142
143void
144JvmtiThreadState::periodic_clean_up() {
145  assert(SafepointSynchronize::is_at_safepoint(), "at safepoint");
146
147  // This iteration is initialized with "_head" instead of "JvmtiThreadState::first()"
148  // because the latter requires the JvmtiThreadState_lock.
149  // This iteration is safe at a safepoint as well, see the NoSafepointVerifier
150  // asserts at all list manipulation sites.
151  for (JvmtiThreadState *state = _head; state != NULL; state = state->next()) {
152    // For each environment thread state corresponding to an invalid environment
153    // unlink it from the list and deallocate it.
154    JvmtiEnvThreadStateIterator it(state);
155    JvmtiEnvThreadState* previous_ets = NULL;
156    JvmtiEnvThreadState* ets = it.first();
157    while (ets != NULL) {
158      if (ets->get_env()->is_valid()) {
159        previous_ets = ets;
160        ets = it.next(ets);
161      } else {
162        // This one isn't valid, remove it from the list and deallocate it
163        JvmtiEnvThreadState* defunct_ets = ets;
164        ets = ets->next();
165        if (previous_ets == NULL) {
166          assert(state->head_env_thread_state() == defunct_ets, "sanity check");
167          state->set_head_env_thread_state(ets);
168        } else {
169          previous_ets->set_next(ets);
170        }
171        delete defunct_ets;
172      }
173    }
174  }
175}
176
177void JvmtiThreadState::add_env(JvmtiEnvBase *env) {
178  assert(JvmtiThreadState_lock->is_locked(), "sanity check");
179
180  JvmtiEnvThreadState *new_ets = new JvmtiEnvThreadState(_thread, env);
181  // add this environment thread state to the end of the list (order is important)
182  {
183    // list deallocation (which occurs at a safepoint) cannot occur simultaneously
184    debug_only(NoSafepointVerifier nosafepoint;)
185
186    JvmtiEnvThreadStateIterator it(this);
187    JvmtiEnvThreadState* previous_ets = NULL;
188    for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
189      previous_ets = ets;
190    }
191    if (previous_ets == NULL) {
192      set_head_env_thread_state(new_ets);
193    } else {
194      previous_ets->set_next(new_ets);
195    }
196  }
197}
198
199
200
201
202void JvmtiThreadState::enter_interp_only_mode() {
203  assert(_thread->get_interp_only_mode() == 0, "entering interp only when mode not zero");
204  _thread->increment_interp_only_mode();
205}
206
207
208void JvmtiThreadState::leave_interp_only_mode() {
209  assert(_thread->get_interp_only_mode() == 1, "leaving interp only when mode not one");
210  _thread->decrement_interp_only_mode();
211}
212
213
214// Helper routine used in several places
215int JvmtiThreadState::count_frames() {
216  guarantee(SafepointSynchronize::is_at_safepoint() ||
217    (JavaThread *)Thread::current() == get_thread(),
218    "must be current thread or at safepoint");
219
220  if (!get_thread()->has_last_Java_frame()) return 0;  // no Java frames
221
222  ResourceMark rm;
223  RegisterMap reg_map(get_thread());
224  javaVFrame *jvf = get_thread()->last_java_vframe(&reg_map);
225  int n = 0;
226  while (jvf != NULL) {
227    Method* method = jvf->method();
228    jvf = jvf->java_sender();
229    n++;
230  }
231  return n;
232}
233
234
235void JvmtiThreadState::invalidate_cur_stack_depth() {
236  guarantee(SafepointSynchronize::is_at_safepoint() ||
237    (JavaThread *)Thread::current() == get_thread(),
238    "must be current thread or at safepoint");
239
240  _cur_stack_depth = UNKNOWN_STACK_DEPTH;
241}
242
243void JvmtiThreadState::incr_cur_stack_depth() {
244  guarantee(JavaThread::current() == get_thread(), "must be current thread");
245
246  if (!is_interp_only_mode()) {
247    _cur_stack_depth = UNKNOWN_STACK_DEPTH;
248  }
249  if (_cur_stack_depth != UNKNOWN_STACK_DEPTH) {
250    ++_cur_stack_depth;
251  }
252}
253
254void JvmtiThreadState::decr_cur_stack_depth() {
255  guarantee(JavaThread::current() == get_thread(), "must be current thread");
256
257  if (!is_interp_only_mode()) {
258    _cur_stack_depth = UNKNOWN_STACK_DEPTH;
259  }
260  if (_cur_stack_depth != UNKNOWN_STACK_DEPTH) {
261    --_cur_stack_depth;
262    assert(_cur_stack_depth >= 0, "incr/decr_cur_stack_depth mismatch");
263  }
264}
265
266int JvmtiThreadState::cur_stack_depth() {
267  guarantee(SafepointSynchronize::is_at_safepoint() ||
268    (JavaThread *)Thread::current() == get_thread(),
269    "must be current thread or at safepoint");
270
271  if (!is_interp_only_mode() || _cur_stack_depth == UNKNOWN_STACK_DEPTH) {
272    _cur_stack_depth = count_frames();
273  } else {
274    // heavy weight assert
275    assert(_cur_stack_depth == count_frames(),
276           "cur_stack_depth out of sync");
277  }
278  return _cur_stack_depth;
279}
280
281bool JvmtiThreadState::may_be_walked() {
282  return (get_thread()->is_being_ext_suspended() || (JavaThread::current() == get_thread()));
283}
284
285
286void JvmtiThreadState::process_pending_step_for_popframe() {
287  // We are single stepping as the last part of the PopFrame() dance
288  // so we have some house keeping to do.
289
290  JavaThread *thr = get_thread();
291  if (thr->popframe_condition() != JavaThread::popframe_inactive) {
292    // If the popframe_condition field is not popframe_inactive, then
293    // we missed all of the popframe_field cleanup points:
294    //
295    // - unpack_frames() was not called (nothing to deopt)
296    // - remove_activation_preserving_args_entry() was not called
297    //   (did not get suspended in a call_vm() family call and did
298    //   not complete a call_vm() family call on the way here)
299    thr->clear_popframe_condition();
300  }
301
302  // clearing the flag indicates we are done with the PopFrame() dance
303  clr_pending_step_for_popframe();
304
305  // If exception was thrown in this frame, need to reset jvmti thread state.
306  // Single stepping may not get enabled correctly by the agent since
307  // exception state is passed in MethodExit event which may be sent at some
308  // time in the future. JDWP agent ignores MethodExit events if caused by
309  // an exception.
310  //
311  if (is_exception_detected()) {
312    clear_exception_state();
313  }
314  // If step is pending for popframe then it may not be
315  // a repeat step. The new_bci and method_id is same as current_bci
316  // and current method_id after pop and step for recursive calls.
317  // Force the step by clearing the last location.
318  JvmtiEnvThreadStateIterator it(this);
319  for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
320    ets->clear_current_location();
321  }
322}
323
324
325// Class:     JvmtiThreadState
326// Function:  update_for_pop_top_frame
327// Description:
328//   This function removes any frame pop notification request for
329//   the top frame and invalidates both the current stack depth and
330//   all cached frameIDs.
331//
332// Called by: PopFrame
333//
334void JvmtiThreadState::update_for_pop_top_frame() {
335  if (is_interp_only_mode()) {
336    // remove any frame pop notification request for the top frame
337    // in any environment
338    int popframe_number = cur_stack_depth();
339    {
340      JvmtiEnvThreadStateIterator it(this);
341      for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
342        if (ets->is_frame_pop(popframe_number)) {
343          ets->clear_frame_pop(popframe_number);
344        }
345      }
346    }
347    // force stack depth to be recalculated
348    invalidate_cur_stack_depth();
349  } else {
350    assert(!is_enabled(JVMTI_EVENT_FRAME_POP), "Must have no framepops set");
351  }
352}
353
354
355void JvmtiThreadState::process_pending_step_for_earlyret() {
356  // We are single stepping as the last part of the ForceEarlyReturn
357  // dance so we have some house keeping to do.
358
359  if (is_earlyret_pending()) {
360    // If the earlyret_state field is not earlyret_inactive, then
361    // we missed all of the earlyret_field cleanup points:
362    //
363    // - remove_activation() was not called
364    //   (did not get suspended in a call_vm() family call and did
365    //   not complete a call_vm() family call on the way here)
366    //
367    // One legitimate way for us to miss all the cleanup points is
368    // if we got here right after handling a compiled return. If that
369    // is the case, then we consider our return from compiled code to
370    // complete the ForceEarlyReturn request and we clear the condition.
371    clr_earlyret_pending();
372    set_earlyret_oop(NULL);
373    clr_earlyret_value();
374  }
375
376  // clearing the flag indicates we are done with
377  // the ForceEarlyReturn() dance
378  clr_pending_step_for_earlyret();
379
380  // If exception was thrown in this frame, need to reset jvmti thread state.
381  // Single stepping may not get enabled correctly by the agent since
382  // exception state is passed in MethodExit event which may be sent at some
383  // time in the future. JDWP agent ignores MethodExit events if caused by
384  // an exception.
385  //
386  if (is_exception_detected()) {
387    clear_exception_state();
388  }
389  // If step is pending for earlyret then it may not be a repeat step.
390  // The new_bci and method_id is same as current_bci and current
391  // method_id after earlyret and step for recursive calls.
392  // Force the step by clearing the last location.
393  JvmtiEnvThreadStateIterator it(this);
394  for (JvmtiEnvThreadState* ets = it.first(); ets != NULL; ets = it.next(ets)) {
395    ets->clear_current_location();
396  }
397}
398
399void JvmtiThreadState::oops_do(OopClosure* f) {
400  f->do_oop((oop*) &_earlyret_oop);
401}
402