1/*
2 * Copyright (c) 2005, 2019, 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/gcVMOperations.hpp"
29#include "memory/resourceArea.hpp"
30#include "memory/universe.hpp"
31#include "oops/oop.inline.hpp"
32#include "oops/typeArrayOop.inline.hpp"
33#include "prims/jvmtiExport.hpp"
34#include "runtime/arguments.hpp"
35#include "runtime/flags/jvmFlag.hpp"
36#include "runtime/globals.hpp"
37#include "runtime/handles.inline.hpp"
38#include "runtime/java.hpp"
39#include "runtime/javaCalls.hpp"
40#include "runtime/os.hpp"
41#include "services/attachListener.hpp"
42#include "services/diagnosticCommand.hpp"
43#include "services/heapDumper.hpp"
44#include "services/writeableFlags.hpp"
45#include "utilities/debug.hpp"
46#include "utilities/formatBuffer.hpp"
47
48volatile bool AttachListener::_initialized;
49
50// Implementation of "properties" command.
51//
52// Invokes VMSupport.serializePropertiesToByteArray to serialize
53// the system properties into a byte array.
54
55static InstanceKlass* load_and_initialize_klass(Symbol* sh, TRAPS) {
56 Klass* k = SystemDictionary::resolve_or_fail(sh, true, CHECK_NULL);
57 InstanceKlass* ik = InstanceKlass::cast(k);
58 if (ik->should_be_initialized()) {
59 ik->initialize(CHECK_NULL);
60 }
61 return ik;
62}
63
64static jint get_properties(AttachOperation* op, outputStream* out, Symbol* serializePropertiesMethod) {
65 Thread* THREAD = Thread::current();
66 HandleMark hm;
67
68 // load VMSupport
69 Symbol* klass = vmSymbols::jdk_internal_vm_VMSupport();
70 InstanceKlass* k = load_and_initialize_klass(klass, THREAD);
71 if (HAS_PENDING_EXCEPTION) {
72 java_lang_Throwable::print(PENDING_EXCEPTION, out);
73 CLEAR_PENDING_EXCEPTION;
74 return JNI_ERR;
75 }
76
77 // invoke the serializePropertiesToByteArray method
78 JavaValue result(T_OBJECT);
79 JavaCallArguments args;
80
81
82 Symbol* signature = vmSymbols::serializePropertiesToByteArray_signature();
83 JavaCalls::call_static(&result,
84 k,
85 serializePropertiesMethod,
86 signature,
87 &args,
88 THREAD);
89 if (HAS_PENDING_EXCEPTION) {
90 java_lang_Throwable::print(PENDING_EXCEPTION, out);
91 CLEAR_PENDING_EXCEPTION;
92 return JNI_ERR;
93 }
94
95 // The result should be a [B
96 oop res = (oop)result.get_jobject();
97 assert(res->is_typeArray(), "just checking");
98 assert(TypeArrayKlass::cast(res->klass())->element_type() == T_BYTE, "just checking");
99
100 // copy the bytes to the output stream
101 typeArrayOop ba = typeArrayOop(res);
102 jbyte* addr = typeArrayOop(res)->byte_at_addr(0);
103 out->print_raw((const char*)addr, ba->length());
104
105 return JNI_OK;
106}
107
108// Implementation of "load" command.
109static jint load_agent(AttachOperation* op, outputStream* out) {
110 // get agent name and options
111 const char* agent = op->arg(0);
112 const char* absParam = op->arg(1);
113 const char* options = op->arg(2);
114
115 // If loading a java agent then need to ensure that the java.instrument module is loaded
116 if (strcmp(agent, "instrument") == 0) {
117 Thread* THREAD = Thread::current();
118 ResourceMark rm(THREAD);
119 HandleMark hm(THREAD);
120 JavaValue result(T_OBJECT);
121 Handle h_module_name = java_lang_String::create_from_str("java.instrument", THREAD);
122 JavaCalls::call_static(&result,
123 SystemDictionary::module_Modules_klass(),
124 vmSymbols::loadModule_name(),
125 vmSymbols::loadModule_signature(),
126 h_module_name,
127 THREAD);
128 if (HAS_PENDING_EXCEPTION) {
129 java_lang_Throwable::print(PENDING_EXCEPTION, out);
130 CLEAR_PENDING_EXCEPTION;
131 return JNI_ERR;
132 }
133 }
134
135 return JvmtiExport::load_agent_library(agent, absParam, options, out);
136}
137
138// Implementation of "properties" command.
139// See also: PrintSystemPropertiesDCmd class
140static jint get_system_properties(AttachOperation* op, outputStream* out) {
141 return get_properties(op, out, vmSymbols::serializePropertiesToByteArray_name());
142}
143
144// Implementation of "agent_properties" command.
145static jint get_agent_properties(AttachOperation* op, outputStream* out) {
146 return get_properties(op, out, vmSymbols::serializeAgentPropertiesToByteArray_name());
147}
148
149// Implementation of "datadump" command.
150//
151// Raises a SIGBREAK signal so that VM dump threads, does deadlock detection,
152// etc. In theory this command should only post a DataDumpRequest to any
153// JVMTI environment that has enabled this event. However it's useful to
154// trigger the SIGBREAK handler.
155
156static jint data_dump(AttachOperation* op, outputStream* out) {
157 if (!ReduceSignalUsage) {
158 AttachListener::pd_data_dump();
159 } else {
160 if (JvmtiExport::should_post_data_dump()) {
161 JvmtiExport::post_data_dump();
162 }
163 }
164 return JNI_OK;
165}
166
167// Implementation of "threaddump" command - essentially a remote ctrl-break
168// See also: ThreadDumpDCmd class
169//
170static jint thread_dump(AttachOperation* op, outputStream* out) {
171 bool print_concurrent_locks = false;
172 bool print_extended_info = false;
173 if (op->arg(0) != NULL) {
174 for (int i = 0; op->arg(0)[i] != 0; ++i) {
175 if (op->arg(0)[i] == 'l') {
176 print_concurrent_locks = true;
177 }
178 if (op->arg(0)[i] == 'e') {
179 print_extended_info = true;
180 }
181 }
182 }
183
184 // thread stacks
185 VM_PrintThreads op1(out, print_concurrent_locks, print_extended_info);
186 VMThread::execute(&op1);
187
188 // JNI global handles
189 VM_PrintJNI op2(out);
190 VMThread::execute(&op2);
191
192 // Deadlock detection
193 VM_FindDeadlocks op3(out);
194 VMThread::execute(&op3);
195
196 return JNI_OK;
197}
198
199// A jcmd attach operation request was received, which will now
200// dispatch to the diagnostic commands used for serviceability functions.
201static jint jcmd(AttachOperation* op, outputStream* out) {
202 Thread* THREAD = Thread::current();
203 // All the supplied jcmd arguments are stored as a single
204 // string (op->arg(0)). This is parsed by the Dcmd framework.
205 DCmd::parse_and_execute(DCmd_Source_AttachAPI, out, op->arg(0), ' ', THREAD);
206 if (HAS_PENDING_EXCEPTION) {
207 java_lang_Throwable::print(PENDING_EXCEPTION, out);
208 out->cr();
209 CLEAR_PENDING_EXCEPTION;
210 return JNI_ERR;
211 }
212 return JNI_OK;
213}
214
215// Implementation of "dumpheap" command.
216// See also: HeapDumpDCmd class
217//
218// Input arguments :-
219// arg0: Name of the dump file
220// arg1: "-live" or "-all"
221jint dump_heap(AttachOperation* op, outputStream* out) {
222 const char* path = op->arg(0);
223 if (path == NULL || path[0] == '\0') {
224 out->print_cr("No dump file specified");
225 } else {
226 bool live_objects_only = true; // default is true to retain the behavior before this change is made
227 const char* arg1 = op->arg(1);
228 if (arg1 != NULL && (strlen(arg1) > 0)) {
229 if (strcmp(arg1, "-all") != 0 && strcmp(arg1, "-live") != 0) {
230 out->print_cr("Invalid argument to dumpheap operation: %s", arg1);
231 return JNI_ERR;
232 }
233 live_objects_only = strcmp(arg1, "-live") == 0;
234 }
235
236 // Request a full GC before heap dump if live_objects_only = true
237 // This helps reduces the amount of unreachable objects in the dump
238 // and makes it easier to browse.
239 HeapDumper dumper(live_objects_only /* request GC */);
240 int res = dumper.dump(op->arg(0));
241 if (res == 0) {
242 out->print_cr("Heap dump file created");
243 } else {
244 // heap dump failed
245 ResourceMark rm;
246 char* error = dumper.error_as_C_string();
247 if (error == NULL) {
248 out->print_cr("Dump failed - reason unknown");
249 } else {
250 out->print_cr("%s", error);
251 }
252 }
253 }
254 return JNI_OK;
255}
256
257// Implementation of "inspectheap" command
258// See also: ClassHistogramDCmd class
259//
260// Input arguments :-
261// arg0: "-live" or "-all"
262// arg1: Name of the dump file or NULL
263static jint heap_inspection(AttachOperation* op, outputStream* out) {
264 bool live_objects_only = true; // default is true to retain the behavior before this change is made
265 outputStream* os = out; // if path not specified or path is NULL, use out
266 fileStream* fs = NULL;
267 const char* arg0 = op->arg(0);
268 if (arg0 != NULL && (strlen(arg0) > 0)) {
269 if (strcmp(arg0, "-all") != 0 && strcmp(arg0, "-live") != 0) {
270 out->print_cr("Invalid argument to inspectheap operation: %s", arg0);
271 return JNI_ERR;
272 }
273 live_objects_only = strcmp(arg0, "-live") == 0;
274 }
275
276 const char* path = op->arg(1);
277 if (path != NULL) {
278 if (path[0] == '\0') {
279 out->print_cr("No dump file specified");
280 } else {
281 // create file
282 fs = new (ResourceObj::C_HEAP, mtInternal) fileStream(path);
283 if (fs == NULL) {
284 out->print_cr("Failed to allocate space for file: %s", path);
285 return JNI_ERR;
286 }
287 os = fs;
288 }
289 }
290
291 VM_GC_HeapInspection heapop(os, live_objects_only /* request full gc */);
292 VMThread::execute(&heapop);
293 if (os != NULL && os != out) {
294 out->print_cr("Heap inspection file created: %s", path);
295 delete fs;
296 }
297 return JNI_OK;
298}
299
300// Implementation of "setflag" command
301static jint set_flag(AttachOperation* op, outputStream* out) {
302
303 const char* name = NULL;
304 if ((name = op->arg(0)) == NULL) {
305 out->print_cr("flag name is missing");
306 return JNI_ERR;
307 }
308
309 FormatBuffer<80> err_msg("%s", "");
310
311 int ret = WriteableFlags::set_flag(op->arg(0), op->arg(1), JVMFlag::ATTACH_ON_DEMAND, err_msg);
312 if (ret != JVMFlag::SUCCESS) {
313 if (ret == JVMFlag::NON_WRITABLE) {
314 // if the flag is not manageable try to change it through
315 // the platform dependent implementation
316 return AttachListener::pd_set_flag(op, out);
317 } else {
318 out->print_cr("%s", err_msg.buffer());
319 }
320
321 return JNI_ERR;
322 }
323 return JNI_OK;
324}
325
326// Implementation of "printflag" command
327// See also: PrintVMFlagsDCmd class
328static jint print_flag(AttachOperation* op, outputStream* out) {
329 const char* name = NULL;
330 if ((name = op->arg(0)) == NULL) {
331 out->print_cr("flag name is missing");
332 return JNI_ERR;
333 }
334 JVMFlag* f = JVMFlag::find_flag((char*)name, strlen(name));
335 if (f) {
336 f->print_as_flag(out);
337 out->cr();
338 } else {
339 out->print_cr("no such flag '%s'", name);
340 }
341 return JNI_OK;
342}
343
344// Table to map operation names to functions.
345
346// names must be of length <= AttachOperation::name_length_max
347static AttachOperationFunctionInfo funcs[] = {
348 { "agentProperties", get_agent_properties },
349 { "datadump", data_dump },
350 { "dumpheap", dump_heap },
351 { "load", load_agent },
352 { "properties", get_system_properties },
353 { "threaddump", thread_dump },
354 { "inspectheap", heap_inspection },
355 { "setflag", set_flag },
356 { "printflag", print_flag },
357 { "jcmd", jcmd },
358 { NULL, NULL }
359};
360
361
362
363// The Attach Listener threads services a queue. It dequeues an operation
364// from the queue, examines the operation name (command), and dispatches
365// to the corresponding function to perform the operation.
366
367static void attach_listener_thread_entry(JavaThread* thread, TRAPS) {
368 os::set_priority(thread, NearMaxPriority);
369
370 assert(thread == Thread::current(), "Must be");
371 assert(thread->stack_base() != NULL && thread->stack_size() > 0,
372 "Should already be setup");
373
374 if (AttachListener::pd_init() != 0) {
375 return;
376 }
377 AttachListener::set_initialized();
378
379 for (;;) {
380 AttachOperation* op = AttachListener::dequeue();
381 if (op == NULL) {
382 return; // dequeue failed or shutdown
383 }
384
385 ResourceMark rm;
386 bufferedStream st;
387 jint res = JNI_OK;
388
389 // handle special detachall operation
390 if (strcmp(op->name(), AttachOperation::detachall_operation_name()) == 0) {
391 AttachListener::detachall();
392 } else if (!EnableDynamicAgentLoading && strcmp(op->name(), "load") == 0) {
393 st.print("Dynamic agent loading is not enabled. "
394 "Use -XX:+EnableDynamicAgentLoading to launch target VM.");
395 res = JNI_ERR;
396 } else {
397 // find the function to dispatch too
398 AttachOperationFunctionInfo* info = NULL;
399 for (int i=0; funcs[i].name != NULL; i++) {
400 const char* name = funcs[i].name;
401 assert(strlen(name) <= AttachOperation::name_length_max, "operation <= name_length_max");
402 if (strcmp(op->name(), name) == 0) {
403 info = &(funcs[i]);
404 break;
405 }
406 }
407
408 // check for platform dependent attach operation
409 if (info == NULL) {
410 info = AttachListener::pd_find_operation(op->name());
411 }
412
413 if (info != NULL) {
414 // dispatch to the function that implements this operation
415 res = (info->func)(op, &st);
416 } else {
417 st.print("Operation %s not recognized!", op->name());
418 res = JNI_ERR;
419 }
420 }
421
422 // operation complete - send result and output to client
423 op->complete(res, &st);
424 }
425}
426
427bool AttachListener::has_init_error(TRAPS) {
428 if (HAS_PENDING_EXCEPTION) {
429 tty->print_cr("Exception in VM (AttachListener::init) : ");
430 java_lang_Throwable::print(PENDING_EXCEPTION, tty);
431 tty->cr();
432
433 CLEAR_PENDING_EXCEPTION;
434
435 return true;
436 } else {
437 return false;
438 }
439}
440
441// Starts the Attach Listener thread
442void AttachListener::init() {
443 EXCEPTION_MARK;
444
445 const char thread_name[] = "Attach Listener";
446 Handle string = java_lang_String::create_from_str(thread_name, THREAD);
447 if (has_init_error(THREAD)) {
448 return;
449 }
450
451 // Initialize thread_oop to put it into the system threadGroup
452 Handle thread_group (THREAD, Universe::system_thread_group());
453 Handle thread_oop = JavaCalls::construct_new_instance(SystemDictionary::Thread_klass(),
454 vmSymbols::threadgroup_string_void_signature(),
455 thread_group,
456 string,
457 THREAD);
458 if (has_init_error(THREAD)) {
459 return;
460 }
461
462 Klass* group = SystemDictionary::ThreadGroup_klass();
463 JavaValue result(T_VOID);
464 JavaCalls::call_special(&result,
465 thread_group,
466 group,
467 vmSymbols::add_method_name(),
468 vmSymbols::thread_void_signature(),
469 thread_oop,
470 THREAD);
471 if (has_init_error(THREAD)) {
472 return;
473 }
474
475 { MutexLocker mu(Threads_lock);
476 JavaThread* listener_thread = new JavaThread(&attach_listener_thread_entry);
477
478 // Check that thread and osthread were created
479 if (listener_thread == NULL || listener_thread->osthread() == NULL) {
480 vm_exit_during_initialization("java.lang.OutOfMemoryError",
481 os::native_thread_creation_failed_msg());
482 }
483
484 java_lang_Thread::set_thread(thread_oop(), listener_thread);
485 java_lang_Thread::set_daemon(thread_oop());
486
487 listener_thread->set_threadObj(thread_oop());
488 Threads::add(listener_thread);
489 Thread::start(listener_thread);
490 }
491}
492
493// Performs clean-up tasks on platforms where we can detect that the last
494// client has detached
495void AttachListener::detachall() {
496 // call the platform dependent clean-up
497 pd_detachall();
498}
499