1 /*
2 * Copyright (c) 2003, 2020, 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/systemDictionary.hpp"
27 #include "interpreter/interpreter.hpp"
28 #include "jvmtifiles/jvmtiEnv.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "prims/jvmtiEnvThreadState.hpp"
31 #include "prims/jvmtiEventController.inline.hpp"
32 #include "prims/jvmtiImpl.hpp"
33 #include "runtime/handles.hpp"
34 #include "runtime/handles.inline.hpp"
35 #include "runtime/interfaceSupport.inline.hpp"
36 #include "runtime/javaCalls.hpp"
37 #include "runtime/signature.hpp"
38 #include "runtime/thread.inline.hpp"
39 #include "runtime/vframe.hpp"
40 #include "runtime/vmOperations.hpp"
41
42
43 ///////////////////////////////////////////////////////////////
44 //
45 // class JvmtiFramePop
46 //
47
48 #ifndef PRODUCT
49 void JvmtiFramePop::print() {
50 tty->print_cr("_frame_number=%d", _frame_number);
51 }
52 #endif
53
54
55 ///////////////////////////////////////////////////////////////
56 //
57 // class JvmtiFramePops - private methods
58 //
59
60 void
61 JvmtiFramePops::set(JvmtiFramePop& fp) {
62 if (_pops->find(fp.frame_number()) < 0) {
63 _pops->append(fp.frame_number());
64 }
65 }
66
67
68 void
69 JvmtiFramePops::clear(JvmtiFramePop& fp) {
70 assert(_pops->length() > 0, "No more frame pops");
71
72 _pops->remove(fp.frame_number());
73 }
74
75
76 int
77 JvmtiFramePops::clear_to(JvmtiFramePop& fp) {
78 int cleared = 0;
79 int index = 0;
80 while (index < _pops->length()) {
81 JvmtiFramePop pop = JvmtiFramePop(_pops->at(index));
82 if (pop.above_on_stack(fp)) {
83 _pops->remove_at(index);
84 ++cleared;
85 } else {
86 ++index;
87 }
88 }
89 return cleared;
90 }
91
92
93 ///////////////////////////////////////////////////////////////
94 //
95 // class JvmtiFramePops - public methods
96 //
97
98 JvmtiFramePops::JvmtiFramePops() {
99 _pops = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<int> (2, mtServiceability);
100 }
101
102 JvmtiFramePops::~JvmtiFramePops() {
103 // return memory to c_heap.
104 delete _pops;
105 }
106
107
108 #ifndef PRODUCT
109 void JvmtiFramePops::print() {
110 ResourceMark rm;
111
112 int n = _pops->length();
113 for (int i=0; i<n; i++) {
114 JvmtiFramePop fp = JvmtiFramePop(_pops->at(i));
115 tty->print("%d: ", i);
116 fp.print();
117 tty->cr();
118 }
119 }
120 #endif
121
122 ///////////////////////////////////////////////////////////////
123 //
124 // class JvmtiEnvThreadState
125 //
126 // Instances of JvmtiEnvThreadState hang off of each JvmtiThreadState,
127 // one per JvmtiEnv.
128 //
129
130 JvmtiEnvThreadState::JvmtiEnvThreadState(JavaThread *thread, JvmtiEnvBase *env) :
131 _event_enable() {
132 _thread = thread;
133 _env = (JvmtiEnv*)env;
134 _next = NULL;
135 _frame_pops = NULL;
136 _current_bci = 0;
137 _current_method_id = NULL;
138 _breakpoint_posted = false;
139 _single_stepping_posted = false;
140 _agent_thread_local_storage_data = NULL;
141 }
142
143 JvmtiEnvThreadState::~JvmtiEnvThreadState() {
144 delete _frame_pops;
145 _frame_pops = NULL;
146 }
147
148 // Given that a new (potential) event has come in,
149 // maintain the current JVMTI location on a per-thread per-env basis
150 // and use it to filter out duplicate events:
151 // - instruction rewrites
152 // - breakpoint followed by single step
153 // - single step at a breakpoint
154 void JvmtiEnvThreadState::compare_and_set_current_location(Method* new_method,
155 address new_location, jvmtiEvent event) {
156
157 int new_bci = new_location - new_method->code_base();
158
159 // The method is identified and stored as a jmethodID which is safe in this
160 // case because the class cannot be unloaded while a method is executing.
161 jmethodID new_method_id = new_method->jmethod_id();
162
163 // the last breakpoint or single step was at this same location
164 if (_current_bci == new_bci && _current_method_id == new_method_id) {
165 switch (event) {
166 case JVMTI_EVENT_BREAKPOINT:
167 // Repeat breakpoint is complicated. If we previously posted a breakpoint
168 // event at this location and if we also single stepped at this location
169 // then we skip the duplicate breakpoint.
170 _breakpoint_posted = _breakpoint_posted && _single_stepping_posted;
171 break;
172 case JVMTI_EVENT_SINGLE_STEP:
173 // Repeat single step is easy: just don't post it again.
174 // If step is pending for popframe then it may not be
175 // a repeat step. The new_bci and method_id is same as current_bci
176 // and current method_id after pop and step for recursive calls.
177 // This has been handled by clearing the location
178 _single_stepping_posted = true;
179 break;
180 default:
181 assert(false, "invalid event value passed");
182 break;
183 }
184 return;
185 }
186
187 set_current_location(new_method_id, new_bci);
188 _breakpoint_posted = false;
189 _single_stepping_posted = false;
190 }
191
192
193 JvmtiFramePops* JvmtiEnvThreadState::get_frame_pops() {
194 #ifdef ASSERT
195 Thread *current = Thread::current();
196 #endif
197 assert(get_thread() == current || current == get_thread()->active_handshaker(),
198 "frame pop data only accessible from same thread or direct handshake");
199 if (_frame_pops == NULL) {
200 _frame_pops = new JvmtiFramePops();
201 assert(_frame_pops != NULL, "_frame_pops != NULL");
202 }
203 return _frame_pops;
204 }
205
206
207 bool JvmtiEnvThreadState::has_frame_pops() {
208 return _frame_pops == NULL? false : (_frame_pops->length() > 0);
209 }
210
211 void JvmtiEnvThreadState::set_frame_pop(int frame_number) {
212 #ifdef ASSERT
213 Thread *current = Thread::current();
214 #endif
215 assert(get_thread() == current || current == get_thread()->active_handshaker(),
216 "frame pop data only accessible from same thread or direct handshake");
217 JvmtiFramePop fpop(frame_number);
218 JvmtiEventController::set_frame_pop(this, fpop);
219 }
220
221
222 void JvmtiEnvThreadState::clear_frame_pop(int frame_number) {
223 #ifdef ASSERT
224 Thread *current = Thread::current();
225 #endif
226 assert(get_thread() == current || current == get_thread()->active_handshaker(),
227 "frame pop data only accessible from same thread or direct handshake");
228 JvmtiFramePop fpop(frame_number);
229 JvmtiEventController::clear_frame_pop(this, fpop);
230 }
231
232
233 void JvmtiEnvThreadState::clear_to_frame_pop(int frame_number) {
234 #ifdef ASSERT
235 Thread *current = Thread::current();
236 #endif
237 assert(get_thread() == current || current == get_thread()->active_handshaker(),
238 "frame pop data only accessible from same thread or direct handshake");
239 JvmtiFramePop fpop(frame_number);
240 JvmtiEventController::clear_to_frame_pop(this, fpop);
241 }
242
243
244 bool JvmtiEnvThreadState::is_frame_pop(int cur_frame_number) {
245 #ifdef ASSERT
246 Thread *current = Thread::current();
247 #endif
248 assert(get_thread() == current || current == get_thread()->active_handshaker(),
249 "frame pop data only accessible from same thread or direct handshake");
250 if (!get_thread()->is_interp_only_mode() || _frame_pops == NULL) {
251 return false;
252 }
253 JvmtiFramePop fp(cur_frame_number);
254 return get_frame_pops()->contains(fp);
255 }
256
257
258 class GetCurrentLocationClosure : public HandshakeClosure {
259 private:
260 jmethodID _method_id;
261 int _bci;
262
263 public:
264 GetCurrentLocationClosure()
265 : HandshakeClosure("GetCurrentLocation"),
266 _method_id(NULL),
267 _bci(0) {}
268 void do_thread(Thread *target) {
269 JavaThread *jt = (JavaThread *)target;
270 ResourceMark rmark; // jt != Thread::current()
271 RegisterMap rm(jt, false);
272 // There can be a race condition between a VM_Operation reaching a safepoint
273 // and the target thread exiting from Java execution.
274 // We must recheck the last Java frame still exists.
275 if (!jt->is_exiting() && jt->has_last_Java_frame()) {
276 javaVFrame* vf = jt->last_java_vframe(&rm);
277 assert(vf != NULL, "must have last java frame");
278 Method* method = vf->method();
279 _method_id = method->jmethod_id();
280 _bci = vf->bci();
281 } else {
282 // Clear current location as the target thread has no Java frames anymore.
283 _method_id = (jmethodID)NULL;
284 _bci = 0;
285 }
286 }
287 void get_current_location(jmethodID *method_id, int *bci) {
288 *method_id = _method_id;
289 *bci = _bci;
290 }
291 };
292
293 void JvmtiEnvThreadState::reset_current_location(jvmtiEvent event_type, bool enabled) {
294 assert(event_type == JVMTI_EVENT_SINGLE_STEP || event_type == JVMTI_EVENT_BREAKPOINT,
295 "must be single-step or breakpoint event");
296
297 // Current location is used to detect the following:
298 // 1) a breakpoint event followed by single-stepping to the same bci
299 // 2) single-step to a bytecode that will be transformed to a fast version
300 // We skip to avoid posting the duplicate single-stepping event.
301
302 // If single-stepping is disabled, clear current location so that
303 // single-stepping to the same method and bcp at a later time will be
304 // detected if single-stepping is enabled at that time (see 4388912).
305
306 // If single-stepping is enabled, set the current location to the
307 // current method and bcp. This covers the following type of case,
308 // e.g., the debugger stepi command:
309 // - bytecode single stepped
310 // - SINGLE_STEP event posted and SINGLE_STEP event disabled
311 // - SINGLE_STEP event reenabled
312 // - bytecode rewritten to fast version
313
314 // If breakpoint event is disabled, clear current location only if
315 // single-stepping is not enabled. Otherwise, keep the thread location
316 // to detect any duplicate events.
317
318 if (enabled) {
319 // If enabling breakpoint, no need to reset.
320 // Can't do anything if empty stack.
321 if (event_type == JVMTI_EVENT_SINGLE_STEP && _thread->has_last_Java_frame()) {
322 jmethodID method_id;
323 int bci;
324 // The java thread stack may not be walkable for a running thread
325 // so get current location with direct handshake.
326 GetCurrentLocationClosure op;
327 if ((Thread::current() == _thread) || (_thread->active_handshaker() != NULL)) {
328 op.do_thread(_thread);
329 } else {
330 Handshake::execute_direct(&op, _thread);
331 }
332 op.get_current_location(&method_id, &bci);
333 set_current_location(method_id, bci);
334 }
335 } else if (event_type == JVMTI_EVENT_SINGLE_STEP || !is_enabled(JVMTI_EVENT_SINGLE_STEP)) {
336 // If this is to disable breakpoint, also check if single-step is not enabled
337 clear_current_location();
338 }
339 }