1 /*
2 * Copyright (c) 2016, 2024, 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/classFileParser.hpp"
27 #include "classfile/classFileStream.hpp"
28 #include "classfile/classLoadInfo.hpp"
29 #include "classfile/javaClasses.inline.hpp"
30 #include "classfile/moduleEntry.hpp"
31 #include "classfile/modules.hpp"
32 #include "classfile/stackMapTable.hpp"
33 #include "classfile/symbolTable.hpp"
34 #include "classfile/verificationType.hpp"
35 #include "interpreter/bytecodes.hpp"
36 #include "jvm.h"
37 #include "jfr/instrumentation/jfrEventClassTransformer.hpp"
38 #include "jfr/jfr.hpp"
39 #include "jfr/jni/jfrJavaSupport.hpp"
40 #include "jfr/jni/jfrUpcalls.hpp"
41 #include "jfr/recorder/jfrRecorder.hpp"
42 #include "jfr/recorder/checkpoint/types/traceid/jfrTraceId.inline.hpp"
43 #include "jfr/support/jfrJdkJfrEvent.hpp"
44 #include "jfr/utilities/jfrBigEndian.hpp"
45 #include "jfr/writers/jfrBigEndianWriter.hpp"
46 #include "logging/log.hpp"
47 #include "memory/allocation.inline.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "oops/array.hpp"
50 #include "oops/constMethod.hpp"
51 #include "oops/instanceKlass.hpp"
52 #include "oops/klass.inline.hpp"
53 #include "oops/method.hpp"
54 #include "prims/jvmtiRedefineClasses.hpp"
55 #include "prims/jvmtiThreadState.hpp"
56 #include "runtime/handles.inline.hpp"
57 #include "runtime/javaThread.hpp"
58 #include "runtime/jniHandles.hpp"
59 #include "runtime/os.hpp"
60 #include "utilities/exceptions.hpp"
61 #include "utilities/globalDefinitions.hpp"
62 #include "utilities/growableArray.hpp"
63 #include "utilities/macros.hpp"
64
65 static const u2 number_of_new_methods = 5;
66 static const u2 number_of_new_fields = 3;
67 static const int extra_stream_bytes = 0x280;
68 static const u2 invalid_cp_index = 0;
69
70 static const char* utf8_constants[] = {
71 "Code", // 0
72 "J", // 1
73 "commit", // 2
74 "eventConfiguration", // 3
75 "duration", // 4
76 "begin", // 5
77 "()V", // 6
78 "isEnabled", // 7
79 "()Z", // 8
80 "end", // 9
81 "shouldCommit", // 10
82 "startTime", // 11 // LAST_REQUIRED_UTF8
83 "Ljdk/jfr/internal/event/EventConfiguration;", // 12
84 "Ljava/lang/Object;", // 13
85 "<clinit>", // 14
86 "jdk/jfr/FlightRecorder", // 15
87 "register", // 16
88 "(Ljava/lang/Class;)V", // 17
89 "StackMapTable", // 18
90 "Exceptions", // 19
91 "LineNumberTable", // 20
92 "LocalVariableTable", // 21
93 "LocalVariableTypeTable", // 22
94 "RuntimeVisibleAnnotation", // 23
95 };
96
97 enum utf8_req_symbols {
98 UTF8_REQ_Code,
99 UTF8_REQ_J_FIELD_DESC,
100 UTF8_REQ_commit,
101 UTF8_REQ_eventConfiguration,
102 UTF8_REQ_duration,
103 UTF8_REQ_begin,
104 UTF8_REQ_EMPTY_VOID_METHOD_DESC,
105 UTF8_REQ_isEnabled,
106 UTF8_REQ_EMPTY_BOOLEAN_METHOD_DESC,
107 UTF8_REQ_end,
108 UTF8_REQ_shouldCommit,
109 UTF8_REQ_startTime,
110 NOF_UTF8_REQ_SYMBOLS
111 };
112
113 enum utf8_opt_symbols {
114 UTF8_OPT_eventConfiguration_FIELD_DESC = NOF_UTF8_REQ_SYMBOLS,
115 UTF8_OPT_LjavaLangObject,
116 UTF8_OPT_clinit,
117 UTF8_OPT_FlightRecorder,
118 UTF8_OPT_register,
119 UTF8_OPT_CLASS_VOID_METHOD_DESC,
120 UTF8_OPT_StackMapTable,
121 UTF8_OPT_Exceptions,
122 UTF8_OPT_LineNumberTable,
123 UTF8_OPT_LocalVariableTable,
124 UTF8_OPT_LocalVariableTypeTable,
125 UTF8_OPT_RuntimeVisibleAnnotation,
126 NOF_UTF8_SYMBOLS
127 };
128
129 static u1 empty_void_method_code_attribute[] = {
130 0x0,
131 0x0,
132 0x0,
133 0xd, // attribute len
134 0x0,
135 0x0, // max stack
136 0x0,
137 0x1, // max locals
138 0x0,
139 0x0,
140 0x0,
141 0x1, // code length
142 Bytecodes::_return,
143 0x0,
144 0x0, // ex table len
145 0x0,
146 0x0 // attributes_count
147 };
148
149 static u1 boolean_method_code_attribute[] = {
150 0x0,
151 0x0,
152 0x0,
153 0xe,
154 0x0,
155 0x1, // max stack
156 0x0,
157 0x1, // max locals
158 0x0,
159 0x0,
160 0x0,
161 0x2,
162 Bytecodes::_iconst_0,
163 Bytecodes::_ireturn,
164 0x0,
165 0x0, // ex table len
166 0x0,
167 0x0, // attributes_count
168 };
169
170 /*
171 Annotation layout.
172
173 enum { // initial annotation layout
174 atype_off = 0, // utf8 such as 'Ljava/lang/annotation/Retention;'
175 count_off = 2, // u2 such as 1 (one value)
176 member_off = 4, // utf8 such as 'value'
177 tag_off = 6, // u1 such as 'c' (type) or 'e' (enum)
178 e_tag_val = 'e',
179 e_type_off = 7, // utf8 such as 'Ljava/lang/annotation/RetentionPolicy;'
180 e_con_off = 9, // utf8 payload, such as 'SOURCE', 'CLASS', 'RUNTIME'
181 e_size = 11, // end of 'e' annotation
182 c_tag_val = 'c', // payload is type
183 c_con_off = 7, // utf8 payload, such as 'I'
184 c_size = 9, // end of 'c' annotation
185 s_tag_val = 's', // payload is String
186 s_con_off = 7, // utf8 payload, such as 'Ljava/lang/String;'
187 s_size = 9,
188 min_size = 6 // smallest possible size (zero members)
189 };
190 */
191
192 static int skip_annotation_value(const address, int, int); // fwd decl
193
194 // Skip an annotation. Return >=limit if there is any problem.
195 static int next_annotation_index(const address buffer, int limit, int index) {
196 assert(buffer != nullptr, "invariant");
197 index += 2; // skip atype
198 if ((index += 2) >= limit) {
199 return limit;
200 }
201 int nof_members = JfrBigEndian::read<int, u2>(buffer + index - 2);
202 while (--nof_members >= 0 && index < limit) {
203 index += 2; // skip member
204 index = skip_annotation_value(buffer, limit, index);
205 }
206 return index;
207 }
208
209 // Skip an annotation value. Return >=limit if there is any problem.
210 static int skip_annotation_value(const address buffer, int limit, int index) {
211 assert(buffer != nullptr, "invariant");
212 // value := switch (tag:u1) {
213 // case B, C, I, S, Z, D, F, J, c: con:u2;
214 // case e: e_class:u2 e_name:u2;
215 // case s: s_con:u2;
216 // case [: do(nval:u2) {value};
217 // case @: annotation;
218 // case s: s_con:u2;
219 // }
220 if ((index += 1) >= limit) {
221 return limit;
222 }
223 const u1 tag = buffer[index - 1];
224 switch (tag) {
225 case 'B':
226 case 'C':
227 case 'I':
228 case 'S':
229 case 'Z':
230 case 'D':
231 case 'F':
232 case 'J':
233 case 'c':
234 case 's':
235 index += 2; // skip con or s_con
236 break;
237 case 'e':
238 index += 4; // skip e_class, e_name
239 break;
240 case '[':
241 {
242 if ((index += 2) >= limit) {
243 return limit;
244 }
245 int nof_values = JfrBigEndian::read<int, u2>(buffer + index - 2);
246 while (--nof_values >= 0 && index < limit) {
247 index = skip_annotation_value(buffer, limit, index);
248 }
249 }
250 break;
251 case '@':
252 index = next_annotation_index(buffer, limit, index);
253 break;
254 default:
255 return limit; // bad tag byte
256 }
257 return index;
258 }
259
260 static constexpr const int number_of_elements_offset = 2;
261 static constexpr const int element_name_offset = number_of_elements_offset + 2;
262 static constexpr const int element_name_size = 2;
263 static constexpr const int value_type_relative_offset = 2;
264 static constexpr const int value_relative_offset = value_type_relative_offset + 1;
265
266 // see JVMS - 4.7.16. The RuntimeVisibleAnnotations Attribute
267
268 class AnnotationElementIterator : public StackObj {
269 private:
270 const InstanceKlass* _ik;
271 const address _buffer;
272 const int _limit; // length of annotation
273 mutable int _current; // element
274 mutable int _next; // element
275
276 int value_index() const {
277 return JfrBigEndian::read<int, u2>(_buffer + _current + value_relative_offset);
278 }
279
280 public:
281 AnnotationElementIterator(const InstanceKlass* ik, address buffer, int limit) : _ik(ik),
282 _buffer(buffer),
283 _limit(limit),
284 _current(element_name_offset),
285 _next(element_name_offset) {
286 assert(_buffer != nullptr, "invariant");
287 assert(_next == element_name_offset, "invariant");
288 assert(_current == element_name_offset, "invariant");
289 }
290
291 bool has_next() const {
292 return _next < _limit;
293 }
294
295 void move_to_next() const {
296 assert(has_next(), "invariant");
297 _current = _next;
298 if (_next < _limit) {
299 _next = skip_annotation_value(_buffer, _limit, _next + element_name_size);
300 }
301 assert(_next <= _limit, "invariant");
302 assert(_current <= _limit, "invariant");
303 }
304
305 int number_of_elements() const {
306 return JfrBigEndian::read<int, u2>(_buffer + number_of_elements_offset);
307 }
308
309 const Symbol* name() const {
310 assert(_current < _next, "invariant");
311 return _ik->constants()->symbol_at(JfrBigEndian::read<int, u2>(_buffer + _current));
312 }
313
314 char value_type() const {
315 return JfrBigEndian::read<char, u1>(_buffer + _current + value_type_relative_offset);
316 }
317
318 jint read_int() const {
319 return _ik->constants()->int_at(value_index());
320 }
321
322 bool read_bool() const {
323 return read_int() != 0;
324 }
325 };
326
327 class AnnotationIterator : public StackObj {
328 private:
329 const InstanceKlass* _ik;
330 // ensure _limit field is declared before _buffer
331 int _limit; // length of annotations array
332 const address _buffer;
333 mutable int _current; // annotation
334 mutable int _next; // annotation
335
336 public:
337 AnnotationIterator(const InstanceKlass* ik, AnnotationArray* ar) : _ik(ik),
338 _limit(ar != nullptr ? ar->length() : 0),
339 _buffer(_limit > 2 ? ar->adr_at(2) : nullptr),
340 _current(0),
341 _next(0) {
342 if (_buffer != nullptr) {
343 _limit -= 2; // subtract sizeof(u2) number of annotations field
344 }
345 }
346 bool has_next() const {
347 return _next < _limit;
348 }
349
350 void move_to_next() const {
351 assert(has_next(), "invariant");
352 _current = _next;
353 if (_next < _limit) {
354 _next = next_annotation_index(_buffer, _limit, _next);
355 }
356 assert(_next <= _limit, "invariant");
357 assert(_current <= _limit, "invariant");
358 }
359
360 const AnnotationElementIterator elements() const {
361 assert(_current < _next, "invariant");
362 return AnnotationElementIterator(_ik, _buffer + _current, _next - _current);
363 }
364
365 const Symbol* type() const {
366 assert(_buffer != nullptr, "invariant");
367 assert(_current < _limit, "invariant");
368 return _ik->constants()->symbol_at(JfrBigEndian::read<int, u2>(_buffer + _current));
369 }
370 };
371
372 static const char value_name[] = "value";
373 static bool has_annotation(const InstanceKlass* ik, const Symbol* annotation_type, bool& value) {
374 assert(annotation_type != nullptr, "invariant");
375 AnnotationArray* class_annotations = ik->class_annotations();
376 if (class_annotations == nullptr) {
377 return false;
378 }
379
380 const AnnotationIterator annotation_iterator(ik, class_annotations);
381 while (annotation_iterator.has_next()) {
382 annotation_iterator.move_to_next();
383 if (annotation_iterator.type() == annotation_type) {
384 // target annotation found
385 static const Symbol* value_symbol =
386 SymbolTable::probe(value_name, sizeof value_name - 1);
387 assert(value_symbol != nullptr, "invariant");
388 const AnnotationElementIterator element_iterator = annotation_iterator.elements();
389 while (element_iterator.has_next()) {
390 element_iterator.move_to_next();
391 if (value_symbol == element_iterator.name()) {
392 // "value" element
393 assert('Z' == element_iterator.value_type(), "invariant");
394 value = element_iterator.read_bool();
395 return true;
396 }
397 }
398 }
399 }
400 return false;
401 }
402
403 // Evaluate to the value of the first found Symbol* annotation type.
404 // Searching moves upwards in the klass hierarchy in order to support
405 // inherited annotations in addition to the ability to override.
406 static bool annotation_value(const InstanceKlass* ik, const Symbol* annotation_type, bool& value) {
407 assert(ik != nullptr, "invariant");
408 assert(annotation_type != nullptr, "invariant");
409 assert(JdkJfrEvent::is_a(ik), "invariant");
410 if (has_annotation(ik, annotation_type, value)) {
411 return true;
412 }
413 InstanceKlass* const super = InstanceKlass::cast(ik->super());
414 return super != nullptr && JdkJfrEvent::is_a(super) ? annotation_value(super, annotation_type, value) : false;
415 }
416
417 static const char jdk_jfr_module_name[] = "jdk.jfr";
418
419 static bool java_base_can_read_jdk_jfr() {
420 static bool can_read = false;
421 if (can_read) {
422 return true;
423 }
424 static Symbol* jdk_jfr_module_symbol = nullptr;
425 if (jdk_jfr_module_symbol == nullptr) {
426 jdk_jfr_module_symbol = SymbolTable::probe(jdk_jfr_module_name, sizeof jdk_jfr_module_name - 1);
427 if (jdk_jfr_module_symbol == nullptr) {
428 return false;
429 }
430 }
431 assert(jdk_jfr_module_symbol != nullptr, "invariant");
432 ModuleEntryTable* const table = Modules::get_module_entry_table(Handle());
433 assert(table != nullptr, "invariant");
434 const ModuleEntry* const java_base_module = table->javabase_moduleEntry();
435 if (java_base_module == nullptr) {
436 return false;
437 }
438 assert(java_base_module != nullptr, "invariant");
439 ModuleEntry* jdk_jfr_module;
440 {
441 MutexLocker ml(Module_lock);
442 jdk_jfr_module = table->lookup_only(jdk_jfr_module_symbol);
443 if (jdk_jfr_module == nullptr) {
444 return false;
445 }
446 }
447 assert(jdk_jfr_module != nullptr, "invariant");
448 if (java_base_module->can_read(jdk_jfr_module)) {
449 can_read = true;
450 }
451 return can_read;
452 }
453
454 static const char registered_constant[] = "Ljdk/jfr/Registered;";
455
456 // Evaluate to the value of the first found "Ljdk/jfr/Registered;" annotation.
457 // Searching moves upwards in the klass hierarchy in order to support
458 // inherited annotations in addition to the ability to override.
459 static bool should_register_klass(const InstanceKlass* ik, bool& untypedEventHandler) {
460 assert(ik != nullptr, "invariant");
461 assert(JdkJfrEvent::is_a(ik), "invariant");
462 assert(!untypedEventHandler, "invariant");
463 static const Symbol* registered_symbol = nullptr;
464 if (registered_symbol == nullptr) {
465 registered_symbol = SymbolTable::probe(registered_constant, sizeof registered_constant - 1);
466 if (registered_symbol == nullptr) {
467 untypedEventHandler = true;
468 return false;
469 }
470 }
471 assert(registered_symbol != nullptr, "invariant");
472 bool value = false; // to be set by annotation_value
473 untypedEventHandler = !(annotation_value(ik, registered_symbol, value) || java_base_can_read_jdk_jfr());
474 return value;
475 }
476
477 /*
478 * Map an utf8 constant back to its CONSTANT_UTF8_INFO
479 */
480 static u2 utf8_info_index(const InstanceKlass* ik, const Symbol* const target, TRAPS) {
481 assert(target != nullptr, "invariant");
482 const ConstantPool* cp = ik->constants();
483 const int cp_len = cp->length();
484 for (int index = 1; index < cp_len; ++index) {
485 const constantTag tag = cp->tag_at(index);
486 if (tag.is_utf8()) {
487 const Symbol* const utf8_sym = cp->symbol_at(index);
488 assert(utf8_sym != nullptr, "invariant");
489 if (utf8_sym == target) {
490 return static_cast<u2>(index);
491 }
492 }
493 }
494 // not in constant pool
495 return invalid_cp_index;
496 }
497
498 #ifdef ASSERT
499 static bool is_index_within_range(u2 index, u2 orig_cp_len, u2 new_cp_entries_len) {
500 return index > 0 && index < orig_cp_len + new_cp_entries_len;
501 }
502 #endif
503
504 static u2 add_utf8_info(JfrBigEndianWriter& writer, const char* utf8_constant, u2 orig_cp_len, u2& new_cp_entries_len) {
505 assert(utf8_constant != nullptr, "invariant");
506 writer.write<u1>(JVM_CONSTANT_Utf8);
507 writer.write_utf8_u2_len(utf8_constant);
508 assert(writer.is_valid(), "invariant");
509 // return index for the added utf8 info
510 return orig_cp_len + new_cp_entries_len++;
511 }
512
513 static u2 add_method_ref_info(JfrBigEndianWriter& writer,
514 u2 cls_name_index,
515 u2 method_index,
516 u2 desc_index,
517 u2 orig_cp_len,
518 u2& number_of_new_constants,
519 TRAPS) {
520 assert(cls_name_index != invalid_cp_index, "invariant");
521 assert(method_index != invalid_cp_index, "invariant");
522 assert(desc_index != invalid_cp_index, "invariant");
523 assert(is_index_within_range(cls_name_index, orig_cp_len, number_of_new_constants), "invariant");
524 assert(is_index_within_range(method_index, orig_cp_len, number_of_new_constants), "invariant");
525 assert(is_index_within_range(desc_index, orig_cp_len, number_of_new_constants), "invariant");
526 writer.write<u1>(JVM_CONSTANT_Class);
527 writer.write<u2>(cls_name_index);
528 const u2 cls_entry_index = orig_cp_len + number_of_new_constants;
529 ++number_of_new_constants;
530 writer.write<u1>(JVM_CONSTANT_NameAndType);
531 writer.write<u2>(method_index);
532 writer.write<u2>(desc_index);
533 const u2 nat_entry_index = orig_cp_len + number_of_new_constants;
534 ++number_of_new_constants;
535 writer.write<u1>(JVM_CONSTANT_Methodref);
536 writer.write<u2>(cls_entry_index);
537 writer.write<u2>(nat_entry_index);
538 // post-increment number_of_new_constants
539 // value returned is the index to the added method_ref
540 return orig_cp_len + number_of_new_constants++;
541 }
542
543 static u2 add_flr_register_method_constants(JfrBigEndianWriter& writer,
544 const u2* utf8_indexes,
545 u2 orig_cp_len,
546 u2& number_of_new_constants,
547 TRAPS) {
548 assert(utf8_indexes != nullptr, "invariant");
549 return add_method_ref_info(writer,
550 utf8_indexes[UTF8_OPT_FlightRecorder],
551 utf8_indexes[UTF8_OPT_register],
552 utf8_indexes[UTF8_OPT_CLASS_VOID_METHOD_DESC],
553 orig_cp_len,
554 number_of_new_constants,
555 THREAD);
556 }
557
558 /*
559 * field_info {
560 * u2 access_flags;
561 * u2 name_index;
562 * u2 descriptor_index;
563 * u2 attributes_count;
564 * attribute_info attributes[attributes_count];
565 * }
566 */
567 static jlong add_field_info(JfrBigEndianWriter& writer, u2 name_index, u2 desc_index, bool is_static = false) {
568 assert(name_index != invalid_cp_index, "invariant");
569 assert(desc_index != invalid_cp_index, "invariant");
570 DEBUG_ONLY(const jlong start_offset = writer.current_offset();)
571 writer.write<u2>(JVM_ACC_SYNTHETIC | JVM_ACC_PRIVATE | (is_static ? JVM_ACC_STATIC : JVM_ACC_TRANSIENT)); // flags
572 writer.write(name_index);
573 writer.write(desc_index);
574 writer.write((u2)0x0); // attributes_count
575 assert(writer.is_valid(), "invariant");
576 DEBUG_ONLY(assert(start_offset + 8 == writer.current_offset(), "invariant");)
577 return writer.current_offset();
578 }
579
580 static u2 add_field_infos(JfrBigEndianWriter& writer, const u2* utf8_indexes, bool untypedEventConfiguration) {
581 assert(utf8_indexes != nullptr, "invariant");
582 add_field_info(writer,
583 utf8_indexes[UTF8_REQ_eventConfiguration],
584 untypedEventConfiguration ? utf8_indexes[UTF8_OPT_LjavaLangObject] : utf8_indexes[UTF8_OPT_eventConfiguration_FIELD_DESC],
585 true); // static
586
587 add_field_info(writer,
588 utf8_indexes[UTF8_REQ_startTime],
589 utf8_indexes[UTF8_REQ_J_FIELD_DESC]);
590
591 add_field_info(writer,
592 utf8_indexes[UTF8_REQ_duration],
593 utf8_indexes[UTF8_REQ_J_FIELD_DESC]);
594
595 return number_of_new_fields;
596 }
597
598 /*
599 * method_info {
600 * u2 access_flags;
601 * u2 name_index;
602 * u2 descriptor_index;
603 * u2 attributes_count;
604 * attribute_info attributes[attributes_count];
605 * }
606 *
607 * Code_attribute {
608 * u2 attribute_name_index;
609 * u4 attribute_length;
610 * u2 max_stack;
611 * u2 max_locals;
612 * u4 code_length;
613 * u1 code[code_length];
614 * u2 exception_table_length;
615 * { u2 start_pc;
616 * u2 end_pc;
617 * u2 handler_pc;
618 * u2 catch_type;
619 * } exception_table[exception_table_length];
620 * u2 attributes_count;
621 * attribute_info attributes[attributes_count];
622 * }
623 */
624
625 static jlong add_method_info(JfrBigEndianWriter& writer,
626 u2 name_index,
627 u2 desc_index,
628 u2 code_index,
629 const u1* const code,
630 const size_t code_len) {
631 assert(name_index > 0, "invariant");
632 assert(desc_index > 0, "invariant");
633 assert(code_index > 0, "invariant");
634 DEBUG_ONLY(const jlong start_offset = writer.current_offset();)
635 writer.write<u2>(JVM_ACC_SYNTHETIC | JVM_ACC_PUBLIC); // flags
636 writer.write(name_index);
637 writer.write(desc_index);
638 writer.write<u2>(0x1); // attributes_count ; 1 for "Code" attribute
639 assert(writer.is_valid(), "invariant");
640 DEBUG_ONLY(assert(start_offset + 8 == writer.current_offset(), "invariant");)
641 // Code attribute
642 writer.write(code_index); // "Code"
643 writer.write_bytes(code, code_len);
644 DEBUG_ONLY(assert((start_offset + 8 + 2 + (jlong)code_len) == writer.current_offset(), "invariant");)
645 return writer.current_offset();
646 }
647
648 /*
649 * On return, the passed stream will be positioned
650 * just after the constant pool section in the classfile
651 * and the cp length is returned.
652 *
653 * Stream should come in at the start position.
654 */
655 static u2 position_stream_after_cp(const ClassFileStream* stream) {
656 assert(stream != nullptr, "invariant");
657 assert(stream->current_offset() == 0, "invariant");
658 stream->skip_u4_fast(2); // 8 bytes skipped
659 const u2 cp_len = stream->get_u2_fast();
660 assert(cp_len > 0, "invariant");
661 // now spin the stream position to just after the constant pool
662 for (u2 index = 1; index < cp_len; ++index) {
663 const u1 tag = stream->get_u1_fast(); // cp tag
664 switch (tag) {
665 case JVM_CONSTANT_Class:
666 case JVM_CONSTANT_String: {
667 stream->skip_u2_fast(1); // skip 2 bytes
668 continue;
669 }
670 case JVM_CONSTANT_Fieldref:
671 case JVM_CONSTANT_Methodref:
672 case JVM_CONSTANT_InterfaceMethodref:
673 case JVM_CONSTANT_Integer:
674 case JVM_CONSTANT_Float:
675 case JVM_CONSTANT_NameAndType:
676 case JVM_CONSTANT_InvokeDynamic: {
677 stream->skip_u4_fast(1); // skip 4 bytes
678 continue;
679 }
680 case JVM_CONSTANT_Long:
681 case JVM_CONSTANT_Double: {
682 stream->skip_u4_fast(2); // skip 8 bytes
683 // Skip entry following eigth-byte constant, see JVM book p. 98
684 ++index;
685 continue;
686 }
687 case JVM_CONSTANT_Utf8: {
688 int utf8_length = static_cast<int>(stream->get_u2_fast());
689 stream->skip_u1_fast(utf8_length); // skip 2 + len bytes
690 continue;
691 }
692 case JVM_CONSTANT_MethodHandle:
693 case JVM_CONSTANT_MethodType: {
694 if (tag == JVM_CONSTANT_MethodHandle) {
695 stream->skip_u1_fast(1);
696 stream->skip_u2_fast(1); // skip 3 bytes
697 }
698 else if (tag == JVM_CONSTANT_MethodType) {
699 stream->skip_u2_fast(1); // skip 3 bytes
700 }
701 }
702 continue;
703 case JVM_CONSTANT_Dynamic:
704 stream->skip_u2_fast(1);
705 stream->skip_u2_fast(1);
706 continue;
707 default:
708 assert(false, "error in skip logic!");
709 break;
710 } // end switch(tag)
711 }
712 return cp_len;
713 }
714
715 /*
716 * On return, the passed stream will be positioned
717 * just after the fields section in the classfile
718 * and the number of fields will be returned.
719 *
720 * Stream should come in positioned just before fields_count
721 */
722 static u2 position_stream_after_fields(const ClassFileStream* stream) {
723 assert(stream != nullptr, "invariant");
724 assert(stream->current_offset() > 0, "invariant");
725 // fields len
726 const u2 orig_fields_len = stream->get_u2_fast();
727 // fields
728 for (u2 i = 0; i < orig_fields_len; ++i) {
729 stream->skip_u2_fast(3);
730 const u2 attrib_info_len = stream->get_u2_fast();
731 for (u2 j = 0; j < attrib_info_len; ++j) {
732 stream->skip_u2_fast(1);
733 stream->skip_u1_fast(static_cast<int>(stream->get_u4_fast()));
734 }
735 }
736 return orig_fields_len;
737 }
738
739 /*
740 * On return, the passed stream will be positioned
741 * just after the methods section in the classfile
742 * and the number of methods will be returned.
743 *
744 * Stream should come in positioned just before methods_count
745 */
746 static u2 position_stream_after_methods(JfrBigEndianWriter& writer,
747 const ClassFileStream* stream,
748 const u2* utf8_indexes,
749 bool register_klass,
750 const Method* clinit_method,
751 u4& orig_method_len_offset) {
752 assert(stream != nullptr, "invariant");
753 assert(stream->current_offset() > 0, "invariant");
754 assert(utf8_indexes != nullptr, "invariant");
755 // We will come back to this location when we
756 // know how many methods there will be.
757 writer.reserve(sizeof(u2));
758 const u2 orig_methods_len = stream->get_u2_fast();
759 // Move copy position past original method_count
760 // in order to not copy the original count
761 orig_method_len_offset += 2;
762 for (u2 i = 0; i < orig_methods_len; ++i) {
763 const u4 method_offset = stream->current_offset();
764 stream->skip_u2_fast(1); // Access Flags
765 const u2 name_index = stream->get_u2_fast(); // Name index
766 stream->skip_u2_fast(1); // Descriptor index
767 const u2 attributes_count = stream->get_u2_fast();
768 for (u2 j = 0; j < attributes_count; ++j) {
769 stream->skip_u2_fast(1);
770 stream->skip_u1_fast(static_cast<int>(stream->get_u4_fast()));
771 }
772 if (clinit_method != nullptr && name_index == clinit_method->name_index()) {
773 // The method just parsed is an existing <clinit> method.
774 // If the class has the @Registered(false) annotation, i.e. marking a class
775 // for opting out from automatic registration, then we do not need to do anything.
776 if (!register_klass) {
777 continue;
778 }
779 // Automatic registration with the jfr system is acccomplished
780 // by pre-pending code to the <clinit> method of the class.
781 // We will need to re-create a new <clinit> in a later step.
782 // For now, ensure that this method is excluded from the methods
783 // being copied.
784 writer.write_bytes(stream->buffer() + orig_method_len_offset,
785 method_offset - orig_method_len_offset);
786 assert(writer.is_valid(), "invariant");
787
788 // Update copy position to skip copy of <clinit> method
789 orig_method_len_offset = stream->current_offset();
790 }
791 }
792 return orig_methods_len;
793 }
794
795 static u2 add_method_infos(JfrBigEndianWriter& writer, const u2* utf8_indexes) {
796 assert(utf8_indexes != nullptr, "invariant");
797 add_method_info(writer,
798 utf8_indexes[UTF8_REQ_begin],
799 utf8_indexes[UTF8_REQ_EMPTY_VOID_METHOD_DESC],
800 utf8_indexes[UTF8_REQ_Code],
801 empty_void_method_code_attribute,
802 sizeof(empty_void_method_code_attribute));
803
804 assert(writer.is_valid(), "invariant");
805
806 add_method_info(writer,
807 utf8_indexes[UTF8_REQ_end],
808 utf8_indexes[UTF8_REQ_EMPTY_VOID_METHOD_DESC],
809 utf8_indexes[UTF8_REQ_Code],
810 empty_void_method_code_attribute,
811 sizeof(empty_void_method_code_attribute));
812
813 assert(writer.is_valid(), "invariant");
814
815 add_method_info(writer,
816 utf8_indexes[UTF8_REQ_commit],
817 utf8_indexes[UTF8_REQ_EMPTY_VOID_METHOD_DESC],
818 utf8_indexes[UTF8_REQ_Code],
819 empty_void_method_code_attribute,
820 sizeof(empty_void_method_code_attribute));
821
822 assert(writer.is_valid(), "invariant");
823
824 add_method_info(writer,
825 utf8_indexes[UTF8_REQ_isEnabled],
826 utf8_indexes[UTF8_REQ_EMPTY_BOOLEAN_METHOD_DESC],
827 utf8_indexes[UTF8_REQ_Code],
828 boolean_method_code_attribute,
829 sizeof(boolean_method_code_attribute));
830
831 assert(writer.is_valid(), "invariant");
832
833 add_method_info(writer,
834 utf8_indexes[UTF8_REQ_shouldCommit],
835 utf8_indexes[UTF8_REQ_EMPTY_BOOLEAN_METHOD_DESC],
836 utf8_indexes[UTF8_REQ_Code],
837 boolean_method_code_attribute,
838 sizeof(boolean_method_code_attribute));
839 assert(writer.is_valid(), "invariant");
840 return number_of_new_methods;
841 }
842
843 static void adjust_exception_table(JfrBigEndianWriter& writer, u2 bci_adjustment_offset, const Method* method, TRAPS) {
844 const u2 ex_table_length = method != nullptr ? (u2)method->exception_table_length() : 0;
845 writer.write<u2>(ex_table_length); // Exception table length
846 if (ex_table_length > 0) {
847 assert(method != nullptr, "invariant");
848 const ExceptionTableElement* const ex_elements = method->exception_table_start();
849 for (int i = 0; i < ex_table_length; ++i) {
850 assert(ex_elements != nullptr, "invariant");
851 writer.write<u2>(ex_elements[i].start_pc + bci_adjustment_offset);
852 writer.write<u2>(ex_elements[i].end_pc + bci_adjustment_offset);
853 writer.write<u2>(ex_elements[i].handler_pc + bci_adjustment_offset);
854 writer.write<u2>(ex_elements[i].catch_type_index); // no adjustment
855 }
856 }
857 }
858
859 enum StackMapFrameTypes : u1 {
860 SAME_FRAME_BEGIN = 0,
861 SAME_FRAME_END = 63,
862 SAME_LOCALS_1_STACK_ITEM_FRAME_BEGIN = 64,
863 SAME_LOCALS_1_STACK_ITEM_FRAME_END = 127,
864 SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED = 247,
865 CHOP_FRAME_BEGIN = 248,
866 CHOP_FRAME_END = 250,
867 SAME_FRAME_EXTENDED = 251,
868 APPEND_FRAME_BEGIN = 252,
869 APPEND_FRAME_END = 254,
870 FULL_FRAME = 255
871 };
872
873 static void adjust_stack_map(JfrBigEndianWriter& writer,
874 Array<u1>* stack_map,
875 const u2* utf8_indexes,
876 u2 bci_adjustment_offset,
877 TRAPS) {
878 assert(stack_map != nullptr, "invariant");
879 assert(utf8_indexes != nullptr, "invariant");
880 writer.write<u2>(utf8_indexes[UTF8_OPT_StackMapTable]);
881 const jlong stack_map_attrib_len_offset = writer.current_offset();
882 writer.reserve(sizeof(u4));
883 StackMapStream stream(stack_map);
884 const u2 stack_map_entries = stream.get_u2(THREAD);
885 // number of entries
886 writer.write<u2>(stack_map_entries); // new stack map entry added
887 const u1 frame_type = stream.get_u1(THREAD);
888 // SAME_FRAME and SAME_LOCALS_1_STACK_ITEM_FRAME encode
889 // their offset_delta into the actual frame type itself.
890 // If such a frame type is the first frame, then we transform
891 // it to a SAME_FRAME_EXTENDED or a SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED frame.
892 // This is done in order to not overflow frame types accidentally
893 // when adjusting the offset_delta. In changing the frame types,
894 // we can work with an explicit u2 offset_delta field (like the other frame types)
895 if (frame_type <= SAME_FRAME_END) {
896 writer.write<u1>(SAME_FRAME_EXTENDED);
897 writer.write<u2>(frame_type + bci_adjustment_offset);
898 } else if (frame_type >= SAME_LOCALS_1_STACK_ITEM_FRAME_BEGIN &&
899 frame_type <= SAME_LOCALS_1_STACK_ITEM_FRAME_END) {
900 writer.write<u1>(SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED);
901 const u2 value = frame_type - SAME_LOCALS_1_STACK_ITEM_FRAME_BEGIN;
902 writer.write<u2>(value + bci_adjustment_offset);
903 } else if (frame_type >= SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
904 // SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED to FULL_FRAME
905 // has a u2 offset_delta field
906 writer.write<u1>(frame_type);
907 writer.write<u2>(stream.get_u2(THREAD) + bci_adjustment_offset);
908 } else {
909 assert(false, "stackMapFrame type is invalid");
910 }
911
912 while (!stream.at_end()) {
913 writer.write<u1>(stream.get_u1(THREAD));
914 }
915
916 u4 stack_map_attrib_len = static_cast<u4>(writer.current_offset() - stack_map_attrib_len_offset);
917 // the stack_map_table_attributes_length value is exclusive
918 stack_map_attrib_len -= 4;
919 writer.write_at_offset(stack_map_attrib_len, stack_map_attrib_len_offset);
920 }
921
922 static void adjust_line_number_table(JfrBigEndianWriter& writer,
923 const u2* utf8_indexes,
924 u4 bci_adjustement_offset,
925 const Method* method,
926 TRAPS) {
927 assert(utf8_indexes != nullptr, "invariant");
928 assert(method != nullptr, "invariant");
929 assert(method->has_linenumber_table(), "invariant");
930 writer.write(utf8_indexes[UTF8_OPT_LineNumberTable]);
931 const jlong lnt_attributes_length_offset = writer.current_offset();
932 writer.reserve(sizeof(u4));
933 const jlong lnt_attributes_entries_offset = writer.current_offset();
934 writer.reserve(sizeof(u2));
935 u1* lnt = method->compressed_linenumber_table();
936 CompressedLineNumberReadStream lnt_stream(lnt);
937 u2 line_number_table_entries = 0;
938 while (lnt_stream.read_pair()) {
939 ++line_number_table_entries;
940 const u2 bci = (u2)lnt_stream.bci();
941 writer.write<u2>(bci + (u2)bci_adjustement_offset);
942 writer.write<u2>((u2)lnt_stream.line());
943 }
944 writer.write_at_offset(line_number_table_entries, lnt_attributes_entries_offset);
945 u4 lnt_table_attributes_len = static_cast<u4>(writer.current_offset() - lnt_attributes_length_offset);
946 // the line_number_table_attributes_length value is exclusive
947 lnt_table_attributes_len -= 4;
948 writer.write_at_offset(lnt_table_attributes_len, lnt_attributes_length_offset);
949 }
950
951 // returns the number of lvtt entries
952 static u2 adjust_local_variable_table(JfrBigEndianWriter& writer,
953 const u2* utf8_indexes,
954 u2 bci_adjustment_offset,
955 const Method* method,
956 TRAPS) {
957 assert(utf8_indexes != nullptr, "invariant");
958 assert(method != nullptr, "invariant");
959 assert(method->has_localvariable_table(), "invariant");
960 writer.write<u2>(utf8_indexes[UTF8_OPT_LocalVariableTable]);
961 const jlong lvt_attributes_length_offset = writer.current_offset();
962 writer.reserve(sizeof(u4));
963 const int lvt_len = method->localvariable_table_length();
964 writer.write<u2>((u2)lvt_len);
965 const LocalVariableTableElement* table = method->localvariable_table_start();
966 assert(table != nullptr, "invariant");
967 u2 num_lvtt_entries = 0;
968 for (int i = 0; i < lvt_len; ++i) {
969 writer.write<u2>(table[i].start_bci + bci_adjustment_offset);
970 writer.write<u2>(table[i].length);
971 writer.write<u2>(table[i].name_cp_index);
972 writer.write<u2>(table[i].descriptor_cp_index);
973 writer.write<u2>(table[i].slot);
974 if (table[i].signature_cp_index > 0) {
975 ++num_lvtt_entries;
976 }
977 }
978 u4 lvt_table_attributes_len = static_cast<u4>(writer.current_offset() - lvt_attributes_length_offset);
979 // the lvt_table_attributes_length value is exclusive
980 lvt_table_attributes_len -= 4;
981 writer.write_at_offset(lvt_table_attributes_len, lvt_attributes_length_offset);
982 return num_lvtt_entries;
983 }
984
985 static void adjust_local_variable_type_table(JfrBigEndianWriter& writer,
986 const u2* utf8_indexes,
987 u2 bci_adjustment_offset,
988 u2 num_lvtt_entries,
989 const Method* method,
990 TRAPS) {
991 assert(num_lvtt_entries > 0, "invariant");
992 writer.write<u2>(utf8_indexes[UTF8_OPT_LocalVariableTypeTable]);
993 const jlong lvtt_attributes_length_offset = writer.current_offset();
994 writer.reserve(sizeof(u4));
995 writer.write<u2>(num_lvtt_entries);
996 const LocalVariableTableElement* table = method->localvariable_table_start();
997 assert(table != nullptr, "invariant");
998 const int lvt_len = method->localvariable_table_length();
999 for (int i = 0; i < lvt_len; ++i) {
1000 if (table[i].signature_cp_index > 0) {
1001 writer.write<u2>(table[i].start_bci + bci_adjustment_offset);
1002 writer.write<u2>(table[i].length);
1003 writer.write<u2>(table[i].name_cp_index);
1004 writer.write<u2>(table[i].signature_cp_index);
1005 writer.write<u2>(table[i].slot);
1006 }
1007 }
1008 u4 lvtt_table_attributes_len = static_cast<u4>(writer.current_offset() - lvtt_attributes_length_offset);
1009 // the lvtt_table_attributes_length value is exclusive
1010 lvtt_table_attributes_len -= 4;
1011 writer.write_at_offset(lvtt_table_attributes_len, lvtt_attributes_length_offset);
1012 }
1013
1014 static void adjust_code_attributes(JfrBigEndianWriter& writer,
1015 const u2* utf8_indexes,
1016 u2 bci_adjustment_offset,
1017 const Method* clinit_method,
1018 TRAPS) {
1019 // "Code" attributes
1020 assert(utf8_indexes != nullptr, "invariant");
1021 const jlong code_attributes_offset = writer.current_offset();
1022 writer.reserve(sizeof(u2));
1023 u2 number_of_code_attributes = 0;
1024 if (clinit_method != nullptr) {
1025 Array<u1>* stack_map = clinit_method->stackmap_data();
1026 if (stack_map != nullptr) {
1027 ++number_of_code_attributes;
1028 adjust_stack_map(writer, stack_map, utf8_indexes, bci_adjustment_offset, THREAD);
1029 assert(writer.is_valid(), "invariant");
1030 }
1031 if (clinit_method != nullptr && clinit_method->has_linenumber_table()) {
1032 ++number_of_code_attributes;
1033 adjust_line_number_table(writer, utf8_indexes, bci_adjustment_offset, clinit_method, THREAD);
1034 assert(writer.is_valid(), "invariant");
1035 }
1036 if (clinit_method != nullptr && clinit_method->has_localvariable_table()) {
1037 ++number_of_code_attributes;
1038 const u2 num_of_lvtt_entries = adjust_local_variable_table(writer, utf8_indexes, bci_adjustment_offset, clinit_method, THREAD);
1039 assert(writer.is_valid(), "invariant");
1040 if (num_of_lvtt_entries > 0) {
1041 ++number_of_code_attributes;
1042 adjust_local_variable_type_table(writer, utf8_indexes, bci_adjustment_offset, num_of_lvtt_entries, clinit_method, THREAD);
1043 assert(writer.is_valid(), "invariant");
1044 }
1045 }
1046 }
1047
1048 // Store the number of code_attributes
1049 writer.write_at_offset(number_of_code_attributes, code_attributes_offset);
1050 }
1051
1052 static jlong insert_clinit_method(const InstanceKlass* ik,
1053 const ClassFileParser& parser,
1054 JfrBigEndianWriter& writer,
1055 u2 orig_constant_pool_len,
1056 const u2* utf8_indexes,
1057 const u2 register_method_ref_index,
1058 const Method* clinit_method,
1059 TRAPS) {
1060 assert(utf8_indexes != nullptr, "invariant");
1061 // The injected code length is always this value.
1062 // This is to ensure that padding can be done
1063 // where needed and to simplify size calculations.
1064 static const u2 injected_code_length = 8;
1065 const u2 name_index = utf8_indexes[UTF8_OPT_clinit];
1066 assert(name_index != invalid_cp_index, "invariant");
1067 const u2 desc_index = utf8_indexes[UTF8_REQ_EMPTY_VOID_METHOD_DESC];
1068 const u2 max_stack = MAX2<u2>(clinit_method != nullptr ? clinit_method->verifier_max_stack() : 1, 1);
1069 const u2 max_locals = MAX2<u2>(clinit_method != nullptr ? clinit_method->max_locals() : 0, 0);
1070 const u2 orig_bytecodes_length = clinit_method != nullptr ? (u2)clinit_method->code_size() : 0;
1071 const address orig_bytecodes = clinit_method != nullptr ? clinit_method->code_base() : nullptr;
1072 const u2 new_code_length = injected_code_length + orig_bytecodes_length;
1073 DEBUG_ONLY(const jlong start_offset = writer.current_offset();)
1074 writer.write<u2>(JVM_ACC_STATIC); // flags
1075 writer.write<u2>(name_index);
1076 writer.write<u2>(desc_index);
1077 writer.write<u2>((u2)0x1); // attributes_count // "Code"
1078 assert(writer.is_valid(), "invariant");
1079 DEBUG_ONLY(assert(start_offset + 8 == writer.current_offset(), "invariant");)
1080 // "Code" attribute
1081 writer.write<u2>(utf8_indexes[UTF8_REQ_Code]); // "Code"
1082 const jlong code_attribute_length_offset = writer.current_offset();
1083 writer.reserve(sizeof(u4));
1084 writer.write<u2>(max_stack); // max stack
1085 writer.write<u2>(max_locals); // max locals
1086 writer.write<u4>((u4)new_code_length); // code length
1087
1088 /* BEGIN CLINIT CODE */
1089
1090 // Note the use of ldc_w here instead of ldc.
1091 // This is to handle all values of "this_class_index"
1092 writer.write<u1>((u1)Bytecodes::_ldc_w);
1093 writer.write<u2>((u2)parser.this_class_index()); // load constant "this class"
1094 writer.write<u1>((u1)Bytecodes::_invokestatic);
1095 // invoke "FlightRecorder.register(Ljava/lang/Class;")
1096 writer.write<u2>(register_method_ref_index);
1097 if (clinit_method == nullptr) {
1098 writer.write<u1>((u1)Bytecodes::_nop);
1099 writer.write<u1>((u1)Bytecodes::_return);
1100 } else {
1101 // If we are pre-pending to original code,
1102 // do padding to minimize disruption to the original.
1103 // It might have dependencies on 4-byte boundaries
1104 // i.e. lookupswitch and tableswitch instructions
1105 writer.write<u1>((u1)Bytecodes::_nop);
1106 writer.write<u1>((u1)Bytecodes::_nop);
1107 // insert original clinit code
1108 writer.write_bytes(orig_bytecodes, orig_bytecodes_length);
1109 }
1110
1111 /* END CLINIT CODE */
1112
1113 assert(writer.is_valid(), "invariant");
1114 adjust_exception_table(writer, injected_code_length, clinit_method, THREAD);
1115 assert(writer.is_valid(), "invariant");
1116 adjust_code_attributes(writer, utf8_indexes, injected_code_length, clinit_method, THREAD);
1117 assert(writer.is_valid(), "invariant");
1118 u4 code_attribute_len = static_cast<u4>(writer.current_offset() - code_attribute_length_offset);
1119 // the code_attribute_length value is exclusive
1120 code_attribute_len -= 4;
1121 writer.write_at_offset(code_attribute_len, code_attribute_length_offset);
1122 return writer.current_offset();
1123 }
1124
1125 static Symbol* begin = nullptr;
1126 static Symbol* end = nullptr;
1127 static Symbol* commit = nullptr;
1128 static Symbol* isEnabled = nullptr;
1129 static Symbol* shouldCommit = nullptr;
1130 static Symbol* void_method_sig = nullptr;
1131 static Symbol* boolean_method_sig = nullptr;
1132
1133 static void initialize_symbols() {
1134 if (begin == nullptr) {
1135 begin = SymbolTable::probe("begin", 5);
1136 assert(begin != nullptr, "invariant");
1137 end = SymbolTable::probe("end", 3);
1138 assert(end != nullptr, "invariant");
1139 commit = SymbolTable::probe("commit", 6);
1140 assert(commit != nullptr, "invariant");
1141 isEnabled = SymbolTable::probe("isEnabled", 9);
1142 assert(isEnabled != nullptr, "invariant");
1143 shouldCommit = SymbolTable::probe("shouldCommit", 12);
1144 assert(shouldCommit != nullptr, "invariant");
1145 void_method_sig = SymbolTable::probe("()V", 3);
1146 assert(void_method_sig != nullptr, "invariant");
1147 boolean_method_sig = SymbolTable::probe("()Z", 3);
1148 assert(boolean_method_sig != nullptr, "invariant");
1149 }
1150 }
1151
1152 // Caller needs ResourceMark
1153 static ClassFileStream* schema_extend_event_klass_bytes(const InstanceKlass* ik, const ClassFileParser& parser, TRAPS) {
1154 DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(THREAD));
1155 initialize_symbols();
1156 static const u2 public_final_flag_mask = JVM_ACC_PUBLIC | JVM_ACC_FINAL;
1157 const ClassFileStream* const orig_stream = parser.clone_stream();
1158 assert(orig_stream != nullptr, "invariant");
1159 const int orig_stream_length = orig_stream->length();
1160 // allocate an identically sized buffer
1161 u1* const new_buffer = NEW_RESOURCE_ARRAY_IN_THREAD_RETURN_NULL(THREAD, u1, orig_stream_length);
1162 if (new_buffer == nullptr) {
1163 return nullptr;
1164 }
1165 assert(new_buffer != nullptr, "invariant");
1166 // memcpy the entire [B
1167 memcpy(new_buffer, orig_stream->buffer(), orig_stream_length);
1168 const u2 orig_cp_len = position_stream_after_cp(orig_stream);
1169 assert(orig_cp_len > 0, "invariant");
1170 assert(orig_stream->current_offset() > 0, "invariant");
1171 orig_stream->skip_u2_fast(3); // access_flags, this_class_index, super_class_index
1172 const u2 iface_len = orig_stream->get_u2_fast();
1173 orig_stream->skip_u2_fast(iface_len);
1174 // fields len
1175 const u2 orig_fields_len = orig_stream->get_u2_fast();
1176 // fields
1177 for (u2 i = 0; i < orig_fields_len; ++i) {
1178 orig_stream->skip_u2_fast(3);
1179 const u2 attrib_info_len = orig_stream->get_u2_fast();
1180 for (u2 j = 0; j < attrib_info_len; ++j) {
1181 orig_stream->skip_u2_fast(1);
1182 const u4 attrib_len = orig_stream->get_u4_fast();
1183 orig_stream->skip_u1_fast(attrib_len);
1184 }
1185 }
1186 // methods
1187 const u2 orig_methods_len = orig_stream->get_u2_fast();
1188 for (u2 i = 0; i < orig_methods_len; ++i) {
1189 const u4 access_flag_offset = orig_stream->current_offset();
1190 const u2 flags = orig_stream->get_u2_fast();
1191 // Rewrite JVM_ACC_FINAL -> JVM_ACC_PUBLIC
1192 if (public_final_flag_mask == flags) {
1193 JfrBigEndianWriter accessflagsrewriter(new_buffer + access_flag_offset, sizeof(u2));
1194 accessflagsrewriter.write<u2>(JVM_ACC_PUBLIC);
1195 assert(accessflagsrewriter.is_valid(), "invariant");
1196 }
1197 orig_stream->skip_u2_fast(2);
1198 const u2 attributes_count = orig_stream->get_u2_fast();
1199 for (u2 j = 0; j < attributes_count; ++j) {
1200 orig_stream->skip_u2_fast(1);
1201 const u4 attrib_len = orig_stream->get_u4_fast();
1202 orig_stream->skip_u1_fast(attrib_len);
1203 }
1204 }
1205 return new ClassFileStream(new_buffer, orig_stream_length, nullptr);
1206 }
1207
1208 // Attempt to locate an existing UTF8_INFO mapping the utf8_constant.
1209 // If no UTF8_INFO exists, add (append) a new one to the constant pool.
1210 static u2 find_or_add_utf8_info(JfrBigEndianWriter& writer,
1211 const InstanceKlass* ik,
1212 const char* const utf8_constant,
1213 u2 orig_cp_len,
1214 u2& added_cp_entries,
1215 TRAPS) {
1216 assert(utf8_constant != nullptr, "invariant");
1217 TempNewSymbol utf8_sym = SymbolTable::new_symbol(utf8_constant);
1218 // lookup existing
1219 const u2 utf8_orig_idx = utf8_info_index(ik, utf8_sym, THREAD);
1220 if (utf8_orig_idx != invalid_cp_index) {
1221 // existing constant pool entry found
1222 return utf8_orig_idx;
1223 }
1224 // no existing match, need to add a new utf8 cp entry
1225 assert(invalid_cp_index == utf8_orig_idx, "invariant");
1226 // add / append new
1227 return add_utf8_info(writer, utf8_constant, orig_cp_len, added_cp_entries);
1228 }
1229
1230 /*
1231 * This routine will resolve the required utf8_constants array
1232 * to their constant pool indexes (mapping to their UTF8_INFO's)
1233 * Only if a constant is actually needed and does not already exist
1234 * will it be added.
1235 *
1236 * The passed in indexes array will be populated with the resolved indexes.
1237 * The number of newly added constant pool entries is returned.
1238 */
1239 static u2 resolve_utf8_indexes(JfrBigEndianWriter& writer,
1240 const InstanceKlass* ik,
1241 u2* const utf8_indexes,
1242 u2 orig_cp_len,
1243 const Method* clinit_method,
1244 bool register_klass,
1245 bool untypedEventConfiguration,
1246 TRAPS) {
1247 assert(utf8_indexes != nullptr, "invariant");
1248 u2 added_cp_entries = 0;
1249 // resolve all required symbols
1250 for (u2 index = 0; index < NOF_UTF8_REQ_SYMBOLS; ++index) {
1251 utf8_indexes[index] = find_or_add_utf8_info(writer, ik, utf8_constants[index], orig_cp_len, added_cp_entries, THREAD);
1252 }
1253
1254 // resolve optional constants
1255 utf8_indexes[UTF8_OPT_eventConfiguration_FIELD_DESC] = untypedEventConfiguration ? invalid_cp_index :
1256 find_or_add_utf8_info(writer, ik, utf8_constants[UTF8_OPT_eventConfiguration_FIELD_DESC], orig_cp_len, added_cp_entries, THREAD);
1257
1258 utf8_indexes[UTF8_OPT_LjavaLangObject] = untypedEventConfiguration ?
1259 find_or_add_utf8_info(writer, ik, utf8_constants[UTF8_OPT_LjavaLangObject], orig_cp_len, added_cp_entries, THREAD) : invalid_cp_index;
1260
1261 if (register_klass) {
1262 utf8_indexes[UTF8_OPT_clinit] =
1263 find_or_add_utf8_info(writer, ik, utf8_constants[UTF8_OPT_clinit], orig_cp_len, added_cp_entries, THREAD);
1264 utf8_indexes[UTF8_OPT_FlightRecorder] =
1265 find_or_add_utf8_info(writer, ik, utf8_constants[UTF8_OPT_FlightRecorder], orig_cp_len, added_cp_entries, THREAD);
1266 utf8_indexes[UTF8_OPT_register] =
1267 find_or_add_utf8_info(writer, ik, utf8_constants[UTF8_OPT_register], orig_cp_len, added_cp_entries, THREAD);
1268 utf8_indexes[UTF8_OPT_CLASS_VOID_METHOD_DESC] =
1269 find_or_add_utf8_info(writer, ik, utf8_constants[UTF8_OPT_CLASS_VOID_METHOD_DESC], orig_cp_len, added_cp_entries, THREAD);
1270 } else {
1271 utf8_indexes[UTF8_OPT_clinit] = invalid_cp_index;
1272 utf8_indexes[UTF8_OPT_FlightRecorder] = invalid_cp_index;
1273 utf8_indexes[UTF8_OPT_register] = invalid_cp_index;
1274 utf8_indexes[UTF8_OPT_CLASS_VOID_METHOD_DESC] = invalid_cp_index;
1275 }
1276
1277 if (clinit_method != nullptr && clinit_method->has_stackmap_table()) {
1278 utf8_indexes[UTF8_OPT_StackMapTable] =
1279 find_or_add_utf8_info(writer, ik, utf8_constants[UTF8_OPT_StackMapTable], orig_cp_len, added_cp_entries, THREAD);
1280 } else {
1281 utf8_indexes[UTF8_OPT_StackMapTable] = invalid_cp_index;
1282 }
1283
1284 if (clinit_method != nullptr && clinit_method->has_linenumber_table()) {
1285 utf8_indexes[UTF8_OPT_LineNumberTable] =
1286 find_or_add_utf8_info(writer, ik, utf8_constants[UTF8_OPT_LineNumberTable], orig_cp_len, added_cp_entries, THREAD);
1287 } else {
1288 utf8_indexes[UTF8_OPT_LineNumberTable] = invalid_cp_index;
1289 }
1290
1291 if (clinit_method != nullptr && clinit_method->has_localvariable_table()) {
1292 utf8_indexes[UTF8_OPT_LocalVariableTable] =
1293 find_or_add_utf8_info(writer, ik, utf8_constants[UTF8_OPT_LocalVariableTable], orig_cp_len, added_cp_entries, THREAD);
1294 utf8_indexes[UTF8_OPT_LocalVariableTypeTable] =
1295 find_or_add_utf8_info(writer, ik, utf8_constants[UTF8_OPT_LocalVariableTypeTable], orig_cp_len, added_cp_entries, THREAD);
1296 } else {
1297 utf8_indexes[UTF8_OPT_LocalVariableTable] = invalid_cp_index;
1298 utf8_indexes[UTF8_OPT_LocalVariableTypeTable] = invalid_cp_index;
1299 }
1300
1301 return added_cp_entries;
1302 }
1303
1304 static u1* schema_extend_event_subklass_bytes(const InstanceKlass* ik,
1305 const ClassFileParser& parser,
1306 jint& size_of_new_bytes,
1307 TRAPS) {
1308 assert(ik != nullptr, "invariant");
1309 // If the class already has a clinit method
1310 // we need to take that into account
1311 const Method* clinit_method = ik->class_initializer();
1312 bool untypedEventHandler = false;
1313 const bool register_klass = should_register_klass(ik, untypedEventHandler);
1314 const ClassFileStream* const orig_stream = parser.clone_stream();
1315 const int orig_stream_size = orig_stream->length();
1316 assert(orig_stream->current_offset() == 0, "invariant");
1317 const u2 orig_cp_len = position_stream_after_cp(orig_stream);
1318 assert(orig_cp_len > 0, "invariant");
1319 assert(orig_stream->current_offset() > 0, "invariant");
1320 // Dimension and allocate a working byte buffer
1321 // to be used in building up a modified class [B.
1322 const jint new_buffer_size = extra_stream_bytes + orig_stream_size;
1323 u1* const new_buffer = NEW_RESOURCE_ARRAY_IN_THREAD_RETURN_NULL(THREAD, u1, new_buffer_size);
1324 if (new_buffer == nullptr) {
1325 log_error(jfr, system) ("Thread local allocation (native) for " SIZE_FORMAT
1326 " bytes failed in JfrEventClassTransformer::on_klass_creation", static_cast<size_t>(new_buffer_size));
1327 return nullptr;
1328 }
1329 assert(new_buffer != nullptr, "invariant");
1330 // [B wrapped in a big endian writer
1331 JfrBigEndianWriter writer(new_buffer, new_buffer_size);
1332 assert(writer.current_offset() == 0, "invariant");
1333 const u4 orig_access_flag_offset = orig_stream->current_offset();
1334 // Copy original stream from the beginning up to AccessFlags
1335 // This means the original constant pool contents are copied unmodified
1336 writer.write_bytes(orig_stream->buffer(), orig_access_flag_offset);
1337 assert(writer.is_valid(), "invariant");
1338 assert(writer.current_offset() == (intptr_t)orig_access_flag_offset, "invariant"); // same positions
1339 // Our writer now sits just after the last original constant pool entry.
1340 // I.e. we are in a good position to append new constant pool entries
1341 // This array will contain the resolved indexes
1342 // in order to reference UTF8_INFO's needed
1343 u2 utf8_indexes[NOF_UTF8_SYMBOLS];
1344 // Resolve_utf8_indexes will be conservative in attempting to
1345 // locate an existing UTF8_INFO; it will only append constants
1346 // that is absolutely required
1347 u2 number_of_new_constants =
1348 resolve_utf8_indexes(writer, ik, utf8_indexes, orig_cp_len, clinit_method, register_klass, untypedEventHandler, THREAD);
1349 // UTF8_INFO entries now added to the constant pool
1350 // In order to invoke a method we would need additional
1351 // constants, JVM_CONSTANT_Class, JVM_CONSTANT_NameAndType
1352 // and JVM_CONSTANT_Methodref.
1353 const u2 flr_register_method_ref_index =
1354 register_klass ?
1355 add_flr_register_method_constants(writer,
1356 utf8_indexes,
1357 orig_cp_len,
1358 number_of_new_constants,
1359 THREAD) : invalid_cp_index;
1360
1361 // New constant pool entries added and all UTF8_INFO indexes resolved
1362 // Now update the class file constant_pool_count with an updated count
1363 writer.write_at_offset<u2>(orig_cp_len + number_of_new_constants, 8);
1364 assert(writer.is_valid(), "invariant");
1365 orig_stream->skip_u2_fast(3); // access_flags, this_class_index, super_class_index
1366 const u2 iface_len = orig_stream->get_u2_fast(); // interfaces
1367 orig_stream->skip_u2_fast(iface_len);
1368 const u4 orig_fields_len_offset = orig_stream->current_offset();
1369 // Copy from AccessFlags up to and including interfaces
1370 writer.write_bytes(orig_stream->buffer() + orig_access_flag_offset,
1371 orig_fields_len_offset - orig_access_flag_offset);
1372 assert(writer.is_valid(), "invariant");
1373 const jlong new_fields_len_offset = writer.current_offset();
1374 const u2 orig_fields_len = position_stream_after_fields(orig_stream);
1375 u4 orig_method_len_offset = orig_stream->current_offset();
1376 // Copy up to and including fields
1377 writer.write_bytes(orig_stream->buffer() + orig_fields_len_offset, orig_method_len_offset - orig_fields_len_offset);
1378 assert(writer.is_valid(), "invariant");
1379 // We are sitting just after the original number of field_infos
1380 // so this is a position where we can add (append) new field_infos
1381 const u2 number_of_new_fields = add_field_infos(writer, utf8_indexes, untypedEventHandler);
1382 assert(writer.is_valid(), "invariant");
1383 const jlong new_method_len_offset = writer.current_offset();
1384 // Additional field_infos added, update classfile fields_count
1385 writer.write_at_offset<u2>(orig_fields_len + number_of_new_fields, new_fields_len_offset);
1386 assert(writer.is_valid(), "invariant");
1387 // Our current location is now at classfile methods_count
1388 const u2 orig_methods_len = position_stream_after_methods(writer,
1389 orig_stream,
1390 utf8_indexes,
1391 register_klass,
1392 clinit_method,
1393 orig_method_len_offset);
1394 const u4 orig_attributes_count_offset = orig_stream->current_offset();
1395 // Copy existing methods
1396 writer.write_bytes(orig_stream->buffer() + orig_method_len_offset, orig_attributes_count_offset - orig_method_len_offset);
1397 assert(writer.is_valid(), "invariant");
1398 // We are sitting just after the original number of method_infos
1399 // so this is a position where we can add (append) new method_infos
1400 u2 number_of_new_methods = add_method_infos(writer, utf8_indexes);
1401
1402 // We have just added the new methods.
1403 //
1404 // What about the state of <clinit>?
1405 // We would need to do:
1406 // 1. Nothing (@Registered(false) annotation)
1407 // 2. Build up a new <clinit> - and if the original class already contains a <clinit>,
1408 // merging will be necessary.
1409 //
1410 if (register_klass) {
1411 insert_clinit_method(ik, parser, writer, orig_cp_len, utf8_indexes, flr_register_method_ref_index, clinit_method, THREAD);
1412 if (clinit_method == nullptr) {
1413 ++number_of_new_methods;
1414 }
1415 }
1416 // Update classfile methods_count
1417 writer.write_at_offset<u2>(orig_methods_len + number_of_new_methods, new_method_len_offset);
1418 assert(writer.is_valid(), "invariant");
1419 // Copy last remaining bytes
1420 writer.write_bytes(orig_stream->buffer() + orig_attributes_count_offset, orig_stream_size - orig_attributes_count_offset);
1421 assert(writer.is_valid(), "invariant");
1422 assert(writer.current_offset() > orig_stream->length(), "invariant");
1423 size_of_new_bytes = (jint)writer.current_offset();
1424 return new_buffer;
1425 }
1426
1427 static bool should_force_instrumentation() {
1428 return !JfrOptionSet::allow_event_retransforms() || JfrEventClassTransformer::is_force_instrumentation();
1429 }
1430
1431 static void log_pending_exception(oop throwable) {
1432 assert(throwable != nullptr, "invariant");
1433 oop msg = java_lang_Throwable::message(throwable);
1434 if (msg != nullptr) {
1435 char* text = java_lang_String::as_utf8_string(msg);
1436 if (text != nullptr) {
1437 log_error(jfr, system) ("%s", text);
1438 }
1439 }
1440 }
1441
1442 static bool has_pending_exception(TRAPS) {
1443 assert(THREAD != nullptr, "invariant");
1444 if (HAS_PENDING_EXCEPTION) {
1445 log_pending_exception(PENDING_EXCEPTION);
1446 CLEAR_PENDING_EXCEPTION;
1447 return true;
1448 }
1449 return false;
1450 }
1451
1452 static bool has_local_method_implementation(const InstanceKlass* ik, const Symbol* name, const Symbol* signature) {
1453 assert(ik != nullptr, "invariant");
1454 assert(name != nullptr, "invariant");
1455 assert(signature != nullptr, "invariant");
1456 return nullptr != ik->find_local_method(name, signature, Klass::OverpassLookupMode::skip, Klass::StaticLookupMode::find,
1457 Klass::PrivateLookupMode::find);
1458 }
1459
1460 // If for a subklass, on initial class load, an implementation exist for any of the final methods declared in Event,
1461 // then constraints are considered breached.
1462 static bool invalid_preconditions_for_subklass_on_initial_load(const InstanceKlass* ik) {
1463 assert(ik != nullptr, "invariant");
1464 return has_local_method_implementation(ik, begin, void_method_sig) ||
1465 has_local_method_implementation(ik, end, void_method_sig) ||
1466 has_local_method_implementation(ik, commit, void_method_sig) ||
1467 has_local_method_implementation(ik, isEnabled, boolean_method_sig) ||
1468 has_local_method_implementation(ik, shouldCommit, boolean_method_sig);
1469 }
1470
1471 static ClassFileStream* schema_extend_event_subklass_bytes(const InstanceKlass* ik, const ClassFileParser& parser, bool& is_instrumented, TRAPS) {
1472 assert(JdkJfrEvent::is_a(ik), "invariant");
1473 assert(!is_instrumented, "invariant");
1474 DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(THREAD));
1475 initialize_symbols();
1476 if (invalid_preconditions_for_subklass_on_initial_load(ik)) {
1477 // Remove the tag denoting this as a jdk.jfr.Event subklass. No instrumentation, hence no events can be written.
1478 // The class is allowed to load as-is, but it is classified as outside of the jfr system.
1479 JdkJfrEvent::remove(ik);
1480 return nullptr;
1481 }
1482 jint size_of_new_bytes = 0;
1483 const u1* new_bytes = schema_extend_event_subklass_bytes(ik, parser, size_of_new_bytes, THREAD);
1484 if (new_bytes == nullptr) {
1485 return nullptr;
1486 }
1487 assert(new_bytes != nullptr, "invariant");
1488 assert(size_of_new_bytes > 0, "invariant");
1489 const bool force_instrumentation = should_force_instrumentation();
1490 if (Jfr::is_recording() || force_instrumentation) {
1491 jint size_of_instrumented_bytes = 0;
1492 unsigned char* instrumented_bytes = nullptr;
1493 const jclass super = static_cast<jclass>(JfrJavaSupport::local_jni_handle(ik->super()->java_mirror(), THREAD));
1494 const jboolean boot_class_loader = ik->class_loader_data()->is_boot_class_loader_data();
1495 JfrUpcalls::new_bytes_eager_instrumentation(JfrTraceId::load_raw(ik),
1496 force_instrumentation,
1497 boot_class_loader,
1498 super,
1499 size_of_new_bytes,
1500 new_bytes,
1501 &size_of_instrumented_bytes,
1502 &instrumented_bytes,
1503 THREAD);
1504 JfrJavaSupport::destroy_local_jni_handle(super);
1505 if (has_pending_exception(THREAD)) {
1506 return nullptr;
1507 }
1508 assert(instrumented_bytes != nullptr, "invariant");
1509 assert(size_of_instrumented_bytes > 0, "invariant");
1510 new_bytes = instrumented_bytes;
1511 size_of_new_bytes = size_of_instrumented_bytes;
1512 is_instrumented = true;
1513 }
1514 return new ClassFileStream(new_bytes, size_of_new_bytes, nullptr);
1515 }
1516
1517 static bool _force_instrumentation = false;
1518
1519 void JfrEventClassTransformer::set_force_instrumentation(bool force_instrumentation) {
1520 _force_instrumentation = force_instrumentation;
1521 }
1522
1523 bool JfrEventClassTransformer::is_force_instrumentation() {
1524 return _force_instrumentation;
1525 }
1526
1527 static ClassFileStream* retransform_bytes(const Klass* existing_klass, const ClassFileParser& parser, bool& is_instrumented, TRAPS) {
1528 assert(existing_klass != nullptr, "invariant");
1529 assert(!is_instrumented, "invariant");
1530 assert(JdkJfrEvent::is_a(existing_klass) || JdkJfrEvent::is_host(existing_klass), "invariant");
1531 DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(THREAD));
1532 jint size_of_new_bytes = 0;
1533 unsigned char* new_bytes = nullptr;
1534 const ClassFileStream* const stream = parser.clone_stream();
1535 assert(stream != nullptr, "invariant");
1536 const jclass clazz = static_cast<jclass>(JfrJavaSupport::local_jni_handle(existing_klass->java_mirror(), THREAD));
1537 JfrUpcalls::on_retransform(JfrTraceId::load_raw(existing_klass),
1538 clazz,
1539 stream->length(),
1540 stream->buffer(),
1541 &size_of_new_bytes,
1542 &new_bytes,
1543 THREAD);
1544 JfrJavaSupport::destroy_local_jni_handle(clazz);
1545 if (has_pending_exception(THREAD)) {
1546 return nullptr;
1547 }
1548 assert(new_bytes != nullptr, "invariant");
1549 assert(size_of_new_bytes > 0, "invariant");
1550 is_instrumented = true;
1551 return new ClassFileStream(new_bytes, size_of_new_bytes, nullptr);
1552 }
1553
1554 // On initial class load.
1555 static void cache_class_file_data(InstanceKlass* new_ik, const ClassFileStream* new_stream, const JavaThread* thread) {
1556 assert(new_ik != nullptr, "invariant");
1557 assert(new_stream != nullptr, "invariant");
1558 assert(thread != nullptr, "invariant");
1559 assert(!thread->has_pending_exception(), "invariant");
1560 if (!JfrOptionSet::allow_retransforms()) {
1561 return;
1562 }
1563 const jint stream_len = new_stream->length();
1564 JvmtiCachedClassFileData* p =
1565 (JvmtiCachedClassFileData*)NEW_C_HEAP_ARRAY_RETURN_NULL(u1, offset_of(JvmtiCachedClassFileData, data) + stream_len, mtInternal);
1566 if (p == nullptr) {
1567 log_error(jfr, system)("Allocation using C_HEAP_ARRAY for " SIZE_FORMAT " bytes failed in JfrEventClassTransformer::cache_class_file_data",
1568 static_cast<size_t>(offset_of(JvmtiCachedClassFileData, data) + stream_len));
1569 return;
1570 }
1571 p->length = stream_len;
1572 memcpy(p->data, new_stream->buffer(), stream_len);
1573 new_ik->set_cached_class_file(p);
1574 }
1575
1576 // On redefine / retransform, in case an agent modified the class, the original bytes are cached onto the scratch klass.
1577 static void transfer_cached_class_file_data(InstanceKlass* ik, InstanceKlass* new_ik, const ClassFileParser& parser, JavaThread* thread) {
1578 assert(ik != nullptr, "invariant");
1579 assert(new_ik != nullptr, "invariant");
1580 JvmtiCachedClassFileData* const p = ik->get_cached_class_file();
1581 if (p != nullptr) {
1582 new_ik->set_cached_class_file(p);
1583 ik->set_cached_class_file(nullptr);
1584 return;
1585 }
1586 // No cached classfile indicates that no agent modified the klass.
1587 // This means that the parser is holding the original bytes. Hence, we cache it onto the scratch klass.
1588 const ClassFileStream* const stream = parser.clone_stream();
1589 cache_class_file_data(new_ik, stream, thread);
1590 }
1591
1592 static void rewrite_klass_pointer(InstanceKlass*& ik, InstanceKlass* new_ik, ClassFileParser& parser, const JavaThread* thread) {
1593 assert(ik != nullptr, "invariant");
1594 assert(new_ik != nullptr, "invariant");
1595 assert(thread != nullptr, "invariant");
1596 assert(IS_EVENT_OR_HOST_KLASS(new_ik), "invariant");
1597 assert(TRACE_ID(ik) == TRACE_ID(new_ik), "invariant");
1598 assert(!thread->has_pending_exception(), "invariant");
1599 // Assign original InstanceKlass* back onto "its" parser object for proper destruction.
1600 parser.set_klass_to_deallocate(ik);
1601 // Finally rewrite the original pointer to the newly created InstanceKlass.
1602 ik = new_ik;
1603 }
1604
1605 // If code size is 1, it is 0xb1, i.e. the return instruction.
1606 static inline bool is_commit_method_instrumented(const Method* m) {
1607 assert(m != nullptr, "invariant");
1608 assert(m->name() == commit, "invariant");
1609 assert(m->constMethod()->code_size() > 0, "invariant");
1610 return m->constMethod()->code_size() > 1;
1611 }
1612
1613 static bool bless_static_commit_method(const Array<Method*>* methods) {
1614 assert(methods != nullptr, "invariant");
1615 for (int i = 0; i < methods->length(); ++i) {
1616 const Method* const m = methods->at(i);
1617 // Method is of the form "static void UserEvent::commit(...)" and instrumented
1618 if (m->is_static() && m->name() == commit && is_commit_method_instrumented(m)) {
1619 BLESS_METHOD(m);
1620 return true;
1621 }
1622 }
1623 return false;
1624 }
1625
1626 static void bless_instance_commit_method(const Array<Method*>* methods) {
1627 assert(methods != nullptr, "invariant");
1628 for (int i = 0; i < methods->length(); ++i) {
1629 const Method* const m = methods->at(i);
1630 // Method is of the form "void UserEvent:commit()" and instrumented
1631 if (!m->is_static() &&
1632 m->name() == commit &&
1633 m->signature() == void_method_sig &&
1634 is_commit_method_instrumented(m)) {
1635 BLESS_METHOD(m);
1636 }
1637 }
1638 }
1639
1640 // A blessed method is a method that is allowed to link to system sensitive code.
1641 // It is primarily the class file schema extended instance 'commit()V' method.
1642 // Jdk events can also define a static commit method with an arbitrary signature.
1643 static void bless_commit_method(const InstanceKlass* new_ik) {
1644 assert(new_ik != nullptr, "invariant");
1645 assert(JdkJfrEvent::is_subklass(new_ik), "invariant");
1646 const Array<Method*>* const methods = new_ik->methods();
1647 if (new_ik->class_loader() == nullptr) {
1648 // JDK events are allowed an additional commit method that is static.
1649 // Search precedence must therefore inspect static methods first.
1650 if (bless_static_commit_method(methods)) {
1651 return;
1652 }
1653 }
1654 bless_instance_commit_method(methods);
1655 }
1656
1657 static void copy_traceid(const InstanceKlass* ik, const InstanceKlass* new_ik) {
1658 assert(ik != nullptr, "invariant");
1659 assert(new_ik != nullptr, "invariant");
1660 new_ik->set_trace_id(ik->trace_id());
1661 assert(TRACE_ID(ik) == TRACE_ID(new_ik), "invariant");
1662 }
1663
1664 static const Klass* klass_being_redefined(const InstanceKlass* ik, JvmtiThreadState* state) {
1665 assert(ik != nullptr, "invariant");
1666 assert(state != nullptr, "invariant");
1667 const GrowableArray<Klass*>* const redef_klasses = state->get_classes_being_redefined();
1668 if (redef_klasses == nullptr || redef_klasses->is_empty()) {
1669 return nullptr;
1670 }
1671 for (int i = 0; i < redef_klasses->length(); ++i) {
1672 const Klass* const existing_klass = redef_klasses->at(i);
1673 assert(existing_klass != nullptr, "invariant");
1674 if (ik->name() == existing_klass->name() && ik->class_loader_data() == existing_klass->class_loader_data()) {
1675 // 'ik' is a scratch klass. Return the klass being redefined.
1676 return existing_klass;
1677 }
1678 }
1679 return nullptr;
1680 }
1681
1682 // Redefining / retransforming?
1683 static const Klass* find_existing_klass(const InstanceKlass* ik, JavaThread* thread) {
1684 assert(ik != nullptr, "invariant");
1685 assert(thread != nullptr, "invariant");
1686 JvmtiThreadState* const state = thread->jvmti_thread_state();
1687 return state != nullptr ? klass_being_redefined(ik, state) : nullptr;
1688 }
1689
1690 static InstanceKlass* create_new_instance_klass(InstanceKlass* ik, ClassFileStream* stream, TRAPS) {
1691 assert(stream != nullptr, "invariant");
1692 ResourceMark rm(THREAD);
1693 ClassLoaderData* const cld = ik->class_loader_data();
1694 Handle pd(THREAD, ik->protection_domain());
1695 Symbol* const class_name = ik->name();
1696 const char* const klass_name = class_name != nullptr ? class_name->as_C_string() : "";
1697 ClassLoadInfo cl_info(pd);
1698 ClassFileParser new_parser(stream,
1699 class_name,
1700 cld,
1701 &cl_info,
1702 ClassFileParser::INTERNAL, // internal visibility
1703 THREAD);
1704 if (HAS_PENDING_EXCEPTION) {
1705 log_pending_exception(PENDING_EXCEPTION);
1706 CLEAR_PENDING_EXCEPTION;
1707 return nullptr;
1708 }
1709 const ClassInstanceInfo* cl_inst_info = cl_info.class_hidden_info_ptr();
1710 InstanceKlass* const new_ik = new_parser.create_instance_klass(false, *cl_inst_info, THREAD);
1711 if (HAS_PENDING_EXCEPTION) {
1712 log_pending_exception(PENDING_EXCEPTION);
1713 CLEAR_PENDING_EXCEPTION;
1714 return nullptr;
1715 }
1716 assert(new_ik != nullptr, "invariant");
1717 assert(new_ik->name() != nullptr, "invariant");
1718 assert(strncmp(ik->name()->as_C_string(), new_ik->name()->as_C_string(), strlen(ik->name()->as_C_string())) == 0, "invariant");
1719 return new_ik;
1720 }
1721
1722 static InstanceKlass* create_instance_klass(InstanceKlass*& ik, ClassFileStream* stream, bool is_initial_load, JavaThread* thread) {
1723 if (stream == nullptr) {
1724 if (is_initial_load) {
1725 log_error(jfr, system)("JfrEventClassTransformer: unable to create ClassFileStream for %s", ik->external_name());
1726 }
1727 return nullptr;
1728 }
1729 InstanceKlass* const new_ik = create_new_instance_klass(ik, stream, thread);
1730 if (new_ik == nullptr) {
1731 if (is_initial_load) {
1732 log_error(jfr, system)("JfrEventClassTransformer: unable to create InstanceKlass for %s", ik->external_name());
1733 }
1734 }
1735 return new_ik;
1736 }
1737
1738 static void transform(InstanceKlass*& ik, ClassFileParser& parser, JavaThread* thread) {
1739 assert(IS_EVENT_OR_HOST_KLASS(ik), "invariant");
1740 bool is_instrumented = false;
1741 ClassFileStream* stream = nullptr;
1742 const Klass* const existing_klass = find_existing_klass(ik, thread);
1743 if (existing_klass != nullptr) {
1744 // There is already a klass defined, implying we are redefining / retransforming.
1745 stream = retransform_bytes(existing_klass, parser, is_instrumented, thread);
1746 } else {
1747 // No existing klass, implying this is the initial load.
1748 stream = JdkJfrEvent::is(ik) ? schema_extend_event_klass_bytes(ik, parser, thread) : schema_extend_event_subklass_bytes(ik, parser, is_instrumented, thread);
1749 }
1750 InstanceKlass* const new_ik = create_instance_klass(ik, stream, existing_klass == nullptr, thread);
1751 if (new_ik == nullptr) {
1752 return;
1753 }
1754 if (existing_klass != nullptr) {
1755 transfer_cached_class_file_data(ik, new_ik, parser, thread);
1756 } else {
1757 cache_class_file_data(new_ik, stream, thread);
1758 }
1759 if (is_instrumented && JdkJfrEvent::is_subklass(new_ik)) {
1760 bless_commit_method(new_ik);
1761 }
1762 copy_traceid(ik, new_ik);
1763 rewrite_klass_pointer(ik, new_ik, parser, thread);
1764 }
1765
1766 // Target for the JFR_ON_KLASS_CREATION hook.
1767 // Extends the class file schema on initial class load or reinstruments on redefine / retransform.
1768 // The passed in parameter 'ik' acts as an in-out parameter: it is rewritten to point to a replaced
1769 // instance of the passed in InstanceKlass. The original 'ik' will be set onto the passed parser,
1770 // for destruction when the parser goes out of scope.
1771 void JfrEventClassTransformer::on_klass_creation(InstanceKlass*& ik, ClassFileParser& parser, TRAPS) {
1772 assert(ik != nullptr, "invariant");
1773 assert(IS_EVENT_OR_HOST_KLASS(ik), "invariant");
1774 if (ik->is_abstract() && !JdkJfrEvent::is(ik)) {
1775 assert(JdkJfrEvent::is_subklass(ik), "invariant");
1776 // Abstract subklasses are not instrumented.
1777 return;
1778 }
1779 ResourceMark rm(THREAD);
1780 HandleMark hm(THREAD);
1781 transform(ik, parser, THREAD);
1782 }
1783
1784 static bool is_static_commit_method_blessed(const Array<Method*>* methods) {
1785 assert(methods != nullptr, "invariant");
1786 for (int i = 0; i < methods->length(); ++i) {
1787 const Method* const m = methods->at(i);
1788 // Must be of form: static void UserEvent::commit(...)
1789 if (m->is_static() && m->name() == commit) {
1790 return IS_METHOD_BLESSED(m);
1791 }
1792 }
1793 return false;
1794 }
1795
1796 static bool is_instance_commit_method_blessed(const Array<Method*>* methods) {
1797 assert(methods != nullptr, "invariant");
1798 for (int i = 0; i < methods->length(); ++i) {
1799 const Method* const m = methods->at(i);
1800 // Must be of form: void UserEvent::commit()
1801 if (!m->is_static() && m->name() == commit && m->signature() == void_method_sig) {
1802 return IS_METHOD_BLESSED(m);
1803 }
1804 }
1805 return false;
1806 }
1807
1808 bool JfrEventClassTransformer::is_instrumented(const InstanceKlass* ik) {
1809 assert(ik != nullptr, "invariant");
1810 assert(JdkJfrEvent::is_subklass(ik), "invariant");
1811 const Array<Method*>* const methods = ik->methods();
1812 if (ik->class_loader() == nullptr) {
1813 // JDK events are allowed an additional commit method that is static.
1814 // Search precedence must therefore inspect static methods first.
1815 if (is_static_commit_method_blessed(methods)) {
1816 return true;
1817 }
1818 }
1819 return is_instance_commit_method_blessed(methods);
1820 }