1 /*
2 * Copyright (c) 2005, 2018, 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/javaClasses.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "gc/shared/vmGCOperations.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "oops/typeArrayOop.inline.hpp"
32 #include "prims/jvmtiExport.hpp"
33 #include "runtime/arguments.hpp"
34 #include "runtime/flags/jvmFlag.hpp"
35 #include "runtime/globals.hpp"
36 #include "runtime/handles.inline.hpp"
37 #include "runtime/java.hpp"
38 #include "runtime/javaCalls.hpp"
39 #include "runtime/os.hpp"
40 #include "services/attachListener.hpp"
41 #include "services/diagnosticCommand.hpp"
42 #include "services/heapDumper.hpp"
43 #include "services/writeableFlags.hpp"
44 #include "utilities/debug.hpp"
45 #include "utilities/formatBuffer.hpp"
46
47 volatile bool AttachListener::_initialized;
48
49 // Implementation of "properties" command.
50 //
51 // Invokes VMSupport.serializePropertiesToByteArray to serialize
52 // the system properties into a byte array.
53
54 static InstanceKlass* load_and_initialize_klass(Symbol* sh, TRAPS) {
55 Klass* k = SystemDictionary::resolve_or_fail(sh, true, CHECK_NULL);
56 InstanceKlass* ik = InstanceKlass::cast(k);
57 if (ik->should_be_initialized()) {
58 ik->initialize(CHECK_NULL);
59 }
60 return ik;
61 }
62
63 static jint get_properties(AttachOperation* op, outputStream* out, Symbol* serializePropertiesMethod) {
64 Thread* THREAD = Thread::current();
65 HandleMark hm;
66
67 // load VMSupport
68 Symbol* klass = vmSymbols::jdk_internal_vm_VMSupport();
69 InstanceKlass* k = load_and_initialize_klass(klass, THREAD);
70 if (HAS_PENDING_EXCEPTION) {
71 java_lang_Throwable::print(PENDING_EXCEPTION, out);
72 CLEAR_PENDING_EXCEPTION;
73 return JNI_ERR;
74 }
75
76 // invoke the serializePropertiesToByteArray method
77 JavaValue result(T_OBJECT);
78 JavaCallArguments args;
79
80
81 Symbol* signature = vmSymbols::serializePropertiesToByteArray_signature();
82 JavaCalls::call_static(&result,
83 k,
84 serializePropertiesMethod,
85 signature,
86 &args,
87 THREAD);
88 if (HAS_PENDING_EXCEPTION) {
89 java_lang_Throwable::print(PENDING_EXCEPTION, out);
90 CLEAR_PENDING_EXCEPTION;
91 return JNI_ERR;
92 }
93
94 // The result should be a [B
95 oop res = (oop)result.get_jobject();
96 assert(res->is_typeArray(), "just checking");
97 assert(TypeArrayKlass::cast(res->klass())->element_type() == T_BYTE, "just checking");
98
99 // copy the bytes to the output stream
100 typeArrayOop ba = typeArrayOop(res);
101 jbyte* addr = typeArrayOop(res)->byte_at_addr(0);
102 out->print_raw((const char*)addr, ba->length());
103
104 return JNI_OK;
105 }
106
107 // Implementation of "load" command.
108 static jint load_agent(AttachOperation* op, outputStream* out) {
109 // get agent name and options
110 const char* agent = op->arg(0);
111 const char* absParam = op->arg(1);
112 const char* options = op->arg(2);
113
114 // If loading a java agent then need to ensure that the java.instrument module is loaded
115 if (strcmp(agent, "instrument") == 0) {
116 Thread* THREAD = Thread::current();
117 ResourceMark rm(THREAD);
118 HandleMark hm(THREAD);
119 JavaValue result(T_OBJECT);
120 Handle h_module_name = java_lang_String::create_from_str("java.instrument", THREAD);
121 JavaCalls::call_static(&result,
122 SystemDictionary::module_Modules_klass(),
123 vmSymbols::loadModule_name(),
124 vmSymbols::loadModule_signature(),
125 h_module_name,
126 THREAD);
127 if (HAS_PENDING_EXCEPTION) {
128 java_lang_Throwable::print(PENDING_EXCEPTION, out);
129 CLEAR_PENDING_EXCEPTION;
130 return JNI_ERR;
131 }
132 }
133
134 return JvmtiExport::load_agent_library(agent, absParam, options, out);
135 }
136
137 // Implementation of "properties" command.
138 // See also: PrintSystemPropertiesDCmd class
139 static jint get_system_properties(AttachOperation* op, outputStream* out) {
140 return get_properties(op, out, vmSymbols::serializePropertiesToByteArray_name());
141 }
142
143 // Implementation of "agent_properties" command.
144 static jint get_agent_properties(AttachOperation* op, outputStream* out) {
145 return get_properties(op, out, vmSymbols::serializeAgentPropertiesToByteArray_name());
146 }
147
148 // Implementation of "datadump" command.
149 //
150 // Raises a SIGBREAK signal so that VM dump threads, does deadlock detection,
151 // etc. In theory this command should only post a DataDumpRequest to any
152 // JVMTI environment that has enabled this event. However it's useful to
153 // trigger the SIGBREAK handler.
154
155 static jint data_dump(AttachOperation* op, outputStream* out) {
156 if (!ReduceSignalUsage) {
157 AttachListener::pd_data_dump();
158 } else {
159 if (JvmtiExport::should_post_data_dump()) {
160 JvmtiExport::post_data_dump();
161 }
162 }
163 return JNI_OK;
164 }
165
166 // Implementation of "threaddump" command - essentially a remote ctrl-break
167 // See also: ThreadDumpDCmd class
168 //
169 static jint thread_dump(AttachOperation* op, outputStream* out) {
170 bool print_concurrent_locks = false;
171 if (op->arg(0) != NULL && strcmp(op->arg(0), "-l") == 0) {
172 print_concurrent_locks = true;
173 }
174
175 // thread stacks
176 VM_PrintThreads op1(out, print_concurrent_locks);
177 VMThread::execute(&op1);
178
179 // JNI global handles
180 VM_PrintJNI op2(out);
181 VMThread::execute(&op2);
182
183 // Deadlock detection
184 VM_FindDeadlocks op3(out);
185 VMThread::execute(&op3);
186
187 return JNI_OK;
188 }
189
190 // A jcmd attach operation request was received, which will now
191 // dispatch to the diagnostic commands used for serviceability functions.
192 static jint jcmd(AttachOperation* op, outputStream* out) {
193 Thread* THREAD = Thread::current();
194 // All the supplied jcmd arguments are stored as a single
195 // string (op->arg(0)). This is parsed by the Dcmd framework.
196 DCmd::parse_and_execute(DCmd_Source_AttachAPI, out, op->arg(0), ' ', THREAD);
197 if (HAS_PENDING_EXCEPTION) {
198 java_lang_Throwable::print(PENDING_EXCEPTION, out);
199 out->cr();
200 CLEAR_PENDING_EXCEPTION;
201 return JNI_ERR;
202 }
203 return JNI_OK;
204 }
205
206 // Implementation of "dumpheap" command.
207 // See also: HeapDumpDCmd class
208 //
209 // Input arguments :-
210 // arg0: Name of the dump file
211 // arg1: "-live" or "-all"
212 jint dump_heap(AttachOperation* op, outputStream* out) {
213 const char* path = op->arg(0);
214 if (path == NULL || path[0] == '\0') {
215 out->print_cr("No dump file specified");
216 } else {
217 bool live_objects_only = true; // default is true to retain the behavior before this change is made
218 const char* arg1 = op->arg(1);
219 if (arg1 != NULL && (strlen(arg1) > 0)) {
220 if (strcmp(arg1, "-all") != 0 && strcmp(arg1, "-live") != 0) {
221 out->print_cr("Invalid argument to dumpheap operation: %s", arg1);
222 return JNI_ERR;
223 }
224 live_objects_only = strcmp(arg1, "-live") == 0;
225 }
226
227 // Request a full GC before heap dump if live_objects_only = true
228 // This helps reduces the amount of unreachable objects in the dump
229 // and makes it easier to browse.
230 HeapDumper dumper(live_objects_only /* request GC */);
231 int res = dumper.dump(op->arg(0));
232 if (res == 0) {
233 out->print_cr("Heap dump file created");
234 } else {
235 // heap dump failed
236 ResourceMark rm;
237 char* error = dumper.error_as_C_string();
238 if (error == NULL) {
239 out->print_cr("Dump failed - reason unknown");
240 } else {
241 out->print_cr("%s", error);
242 }
243 }
244 }
245 return JNI_OK;
246 }
247
248 // Implementation of "inspectheap" command
249 // See also: ClassHistogramDCmd class
250 //
251 // Input arguments :-
252 // arg0: "-live" or "-all"
253 static jint heap_inspection(AttachOperation* op, outputStream* out) {
254 bool live_objects_only = true; // default is true to retain the behavior before this change is made
255 const char* arg0 = op->arg(0);
256 if (arg0 != NULL && (strlen(arg0) > 0)) {
257 if (strcmp(arg0, "-all") != 0 && strcmp(arg0, "-live") != 0) {
258 out->print_cr("Invalid argument to inspectheap operation: %s", arg0);
259 return JNI_ERR;
260 }
261 live_objects_only = strcmp(arg0, "-live") == 0;
262 }
263 VM_GC_HeapInspection heapop(out, live_objects_only /* request full gc */);
264 VMThread::execute(&heapop);
265 return JNI_OK;
266 }
267
268 // Implementation of "setflag" command
269 static jint set_flag(AttachOperation* op, outputStream* out) {
270
271 const char* name = NULL;
272 if ((name = op->arg(0)) == NULL) {
273 out->print_cr("flag name is missing");
274 return JNI_ERR;
275 }
276
277 FormatBuffer<80> err_msg("%s", "");
278
279 int ret = WriteableFlags::set_flag(op->arg(0), op->arg(1), JVMFlag::ATTACH_ON_DEMAND, err_msg);
280 if (ret != JVMFlag::SUCCESS) {
281 if (ret == JVMFlag::NON_WRITABLE) {
282 // if the flag is not manageable try to change it through
283 // the platform dependent implementation
284 return AttachListener::pd_set_flag(op, out);
285 } else {
286 out->print_cr("%s", err_msg.buffer());
287 }
288
289 return JNI_ERR;
290 }
291 return JNI_OK;
292 }
293
294 // Implementation of "printflag" command
295 // See also: PrintVMFlagsDCmd class
296 static jint print_flag(AttachOperation* op, outputStream* out) {
297 const char* name = NULL;
298 if ((name = op->arg(0)) == NULL) {
299 out->print_cr("flag name is missing");
300 return JNI_ERR;
301 }
302 JVMFlag* f = JVMFlag::find_flag((char*)name, strlen(name));
303 if (f) {
304 f->print_as_flag(out);
305 out->cr();
306 } else {
307 out->print_cr("no such flag '%s'", name);
308 }
309 return JNI_OK;
310 }
311
312 // Table to map operation names to functions.
313
314 // names must be of length <= AttachOperation::name_length_max
315 static AttachOperationFunctionInfo funcs[] = {
316 { "agentProperties", get_agent_properties },
317 { "datadump", data_dump },
318 { "dumpheap", dump_heap },
319 { "load", load_agent },
320 { "properties", get_system_properties },
321 { "threaddump", thread_dump },
322 { "inspectheap", heap_inspection },
323 { "setflag", set_flag },
324 { "printflag", print_flag },
325 { "jcmd", jcmd },
326 { NULL, NULL }
327 };
328
329
330
331 // The Attach Listener threads services a queue. It dequeues an operation
332 // from the queue, examines the operation name (command), and dispatches
333 // to the corresponding function to perform the operation.
334
335 static void attach_listener_thread_entry(JavaThread* thread, TRAPS) {
336 os::set_priority(thread, NearMaxPriority);
337
338 assert(thread == Thread::current(), "Must be");
339 assert(thread->stack_base() != NULL && thread->stack_size() > 0,
340 "Should already be setup");
341
342 if (AttachListener::pd_init() != 0) {
343 return;
344 }
345 AttachListener::set_initialized();
346
347 for (;;) {
348 AttachOperation* op = AttachListener::dequeue();
349 if (op == NULL) {
350 return; // dequeue failed or shutdown
351 }
352
353 ResourceMark rm;
354 bufferedStream st;
355 jint res = JNI_OK;
356
357 // handle special detachall operation
358 if (strcmp(op->name(), AttachOperation::detachall_operation_name()) == 0) {
359 AttachListener::detachall();
360 } else if (!EnableDynamicAgentLoading && strcmp(op->name(), "load") == 0) {
361 st.print("Dynamic agent loading is not enabled. "
362 "Use -XX:+EnableDynamicAgentLoading to launch target VM.");
363 res = JNI_ERR;
364 } else {
365 // find the function to dispatch too
366 AttachOperationFunctionInfo* info = NULL;
367 for (int i=0; funcs[i].name != NULL; i++) {
368 const char* name = funcs[i].name;
369 assert(strlen(name) <= AttachOperation::name_length_max, "operation <= name_length_max");
370 if (strcmp(op->name(), name) == 0) {
371 info = &(funcs[i]);
372 break;
373 }
374 }
375
376 // check for platform dependent attach operation
377 if (info == NULL) {
378 info = AttachListener::pd_find_operation(op->name());
379 }
380
381 if (info != NULL) {
382 // dispatch to the function that implements this operation
383 res = (info->func)(op, &st);
384 } else {
385 st.print("Operation %s not recognized!", op->name());
386 res = JNI_ERR;
387 }
388 }
389
390 // operation complete - send result and output to client
391 op->complete(res, &st);
392 }
393 }
394
395 bool AttachListener::has_init_error(TRAPS) {
396 if (HAS_PENDING_EXCEPTION) {
397 tty->print_cr("Exception in VM (AttachListener::init) : ");
398 java_lang_Throwable::print(PENDING_EXCEPTION, tty);
399 tty->cr();
400
401 CLEAR_PENDING_EXCEPTION;
402
403 return true;
404 } else {
405 return false;
406 }
407 }
408
409 // Starts the Attach Listener thread
410 void AttachListener::init() {
411 EXCEPTION_MARK;
412
413 const char thread_name[] = "Attach Listener";
414 Handle string = java_lang_String::create_from_str(thread_name, THREAD);
415 if (has_init_error(THREAD)) {
416 return;
417 }
418
419 // Initialize thread_oop to put it into the system threadGroup
420 Handle thread_group (THREAD, Universe::system_thread_group());
421 Handle thread_oop = JavaCalls::construct_new_instance(SystemDictionary::Thread_klass(),
422 vmSymbols::threadgroup_string_void_signature(),
423 thread_group,
424 string,
425 THREAD);
426 if (has_init_error(THREAD)) {
427 return;
428 }
429
430 Klass* group = SystemDictionary::ThreadGroup_klass();
431 JavaValue result(T_VOID);
432 JavaCalls::call_special(&result,
433 thread_group,
434 group,
435 vmSymbols::add_method_name(),
436 vmSymbols::thread_void_signature(),
437 thread_oop,
438 THREAD);
439 if (has_init_error(THREAD)) {
440 return;
441 }
442
443 { MutexLocker mu(Threads_lock);
444 JavaThread* listener_thread = new JavaThread(&attach_listener_thread_entry);
445
446 // Check that thread and osthread were created
447 if (listener_thread == NULL || listener_thread->osthread() == NULL) {
448 vm_exit_during_initialization("java.lang.OutOfMemoryError",
449 os::native_thread_creation_failed_msg());
450 }
451
452 java_lang_Thread::set_thread(thread_oop(), listener_thread);
453 java_lang_Thread::set_daemon(thread_oop());
454
455 listener_thread->set_threadObj(thread_oop());
456 Threads::add(listener_thread);
457 Thread::start(listener_thread);
458 }
459 }
460
461 // Performs clean-up tasks on platforms where we can detect that the last
462 // client has detached
463 void AttachListener::detachall() {
464 // call the platform dependent clean-up
465 pd_detachall();
466 }