1/*
2 * Copyright (c) 2003, 2017, 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
49void 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
60void
61JvmtiFramePops::set(JvmtiFramePop& fp) {
62 if (_pops->find(fp.frame_number()) < 0) {
63 _pops->append(fp.frame_number());
64 }
65}
66
67
68void
69JvmtiFramePops::clear(JvmtiFramePop& fp) {
70 assert(_pops->length() > 0, "No more frame pops");
71
72 _pops->remove(fp.frame_number());
73}
74
75
76int
77JvmtiFramePops::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
98JvmtiFramePops::JvmtiFramePops() {
99 _pops = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int> (2, true);
100}
101
102JvmtiFramePops::~JvmtiFramePops() {
103 // return memory to c_heap.
104 delete _pops;
105}
106
107
108#ifndef PRODUCT
109void 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
130JvmtiEnvThreadState::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
143JvmtiEnvThreadState::~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
154void 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
193JvmtiFramePops* JvmtiEnvThreadState::get_frame_pops() {
194 assert(get_thread() == Thread::current() || SafepointSynchronize::is_at_safepoint(),
195 "frame pop data only accessible from same thread or at safepoint");
196 if (_frame_pops == NULL) {
197 _frame_pops = new JvmtiFramePops();
198 assert(_frame_pops != NULL, "_frame_pops != NULL");
199 }
200 return _frame_pops;
201}
202
203
204bool JvmtiEnvThreadState::has_frame_pops() {
205 return _frame_pops == NULL? false : (_frame_pops->length() > 0);
206}
207
208void JvmtiEnvThreadState::set_frame_pop(int frame_number) {
209 assert(get_thread() == Thread::current() || SafepointSynchronize::is_at_safepoint(),
210 "frame pop data only accessible from same thread or at safepoint");
211 JvmtiFramePop fpop(frame_number);
212 JvmtiEventController::set_frame_pop(this, fpop);
213}
214
215
216void JvmtiEnvThreadState::clear_frame_pop(int frame_number) {
217 assert(get_thread() == Thread::current() || SafepointSynchronize::is_at_safepoint(),
218 "frame pop data only accessible from same thread or at safepoint");
219 JvmtiFramePop fpop(frame_number);
220 JvmtiEventController::clear_frame_pop(this, fpop);
221}
222
223
224void JvmtiEnvThreadState::clear_to_frame_pop(int frame_number) {
225 assert(get_thread() == Thread::current() || SafepointSynchronize::is_at_safepoint(),
226 "frame pop data only accessible from same thread or at safepoint");
227 JvmtiFramePop fpop(frame_number);
228 JvmtiEventController::clear_to_frame_pop(this, fpop);
229}
230
231
232bool JvmtiEnvThreadState::is_frame_pop(int cur_frame_number) {
233 assert(get_thread() == Thread::current() || SafepointSynchronize::is_at_safepoint(),
234 "frame pop data only accessible from same thread or at safepoint");
235 if (!get_thread()->is_interp_only_mode() || _frame_pops == NULL) {
236 return false;
237 }
238 JvmtiFramePop fp(cur_frame_number);
239 return get_frame_pops()->contains(fp);
240}
241
242
243class VM_GetCurrentLocation : public VM_Operation {
244 private:
245 JavaThread *_thread;
246 jmethodID _method_id;
247 int _bci;
248
249 public:
250 VM_GetCurrentLocation(JavaThread *thread) {
251 _thread = thread;
252 }
253 VMOp_Type type() const { return VMOp_GetCurrentLocation; }
254 void doit() {
255 ResourceMark rmark; // _thread != Thread::current()
256 RegisterMap rm(_thread, false);
257 // There can be a race condition between a VM_Operation reaching a safepoint
258 // and the target thread exiting from Java execution.
259 // We must recheck the last Java frame still exists.
260 if (!_thread->is_exiting() && _thread->has_last_Java_frame()) {
261 javaVFrame* vf = _thread->last_java_vframe(&rm);
262 assert(vf != NULL, "must have last java frame");
263 Method* method = vf->method();
264 _method_id = method->jmethod_id();
265 _bci = vf->bci();
266 } else {
267 // Clear current location as the target thread has no Java frames anymore.
268 _method_id = (jmethodID)NULL;
269 _bci = 0;
270 }
271 }
272 void get_current_location(jmethodID *method_id, int *bci) {
273 *method_id = _method_id;
274 *bci = _bci;
275 }
276};
277
278void JvmtiEnvThreadState::reset_current_location(jvmtiEvent event_type, bool enabled) {
279 assert(event_type == JVMTI_EVENT_SINGLE_STEP || event_type == JVMTI_EVENT_BREAKPOINT,
280 "must be single-step or breakpoint event");
281
282 // Current location is used to detect the following:
283 // 1) a breakpoint event followed by single-stepping to the same bci
284 // 2) single-step to a bytecode that will be transformed to a fast version
285 // We skip to avoid posting the duplicate single-stepping event.
286
287 // If single-stepping is disabled, clear current location so that
288 // single-stepping to the same method and bcp at a later time will be
289 // detected if single-stepping is enabled at that time (see 4388912).
290
291 // If single-stepping is enabled, set the current location to the
292 // current method and bcp. This covers the following type of case,
293 // e.g., the debugger stepi command:
294 // - bytecode single stepped
295 // - SINGLE_STEP event posted and SINGLE_STEP event disabled
296 // - SINGLE_STEP event reenabled
297 // - bytecode rewritten to fast version
298
299 // If breakpoint event is disabled, clear current location only if
300 // single-stepping is not enabled. Otherwise, keep the thread location
301 // to detect any duplicate events.
302
303 if (enabled) {
304 // If enabling breakpoint, no need to reset.
305 // Can't do anything if empty stack.
306 if (event_type == JVMTI_EVENT_SINGLE_STEP && _thread->has_last_Java_frame()) {
307 jmethodID method_id;
308 int bci;
309 // The java thread stack may not be walkable for a running thread
310 // so get current location at safepoint.
311 VM_GetCurrentLocation op(_thread);
312 VMThread::execute(&op);
313 op.get_current_location(&method_id, &bci);
314 set_current_location(method_id, bci);
315 }
316 } else if (event_type == JVMTI_EVENT_SINGLE_STEP || !is_enabled(JVMTI_EVENT_SINGLE_STEP)) {
317 // If this is to disable breakpoint, also check if single-step is not enabled
318 clear_current_location();
319 }
320}
321