Thu, 24 Jan 2013 22:13:32 -0800
8005128: JSR 292: the mlvm redefineClassInBootstrap test crashes in ConstantPool::compare_entry_to
Summary: When constant pool is copied in merge_constant_pools the invokedynamic operands must be copied before.
Reviewed-by: coleenp, twisti
Contributed-by: serguei.spitsyn@oracle.com
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25 #ifndef SHARE_VM_PRIMS_JVMTIREDEFINECLASSES_HPP
26 #define SHARE_VM_PRIMS_JVMTIREDEFINECLASSES_HPP
28 #include "jvmtifiles/jvmtiEnv.hpp"
29 #include "memory/oopFactory.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/objArrayKlass.hpp"
32 #include "oops/objArrayOop.hpp"
33 #include "prims/jvmtiRedefineClassesTrace.hpp"
34 #include "runtime/vm_operations.hpp"
36 // Introduction:
37 //
38 // The RedefineClasses() API is used to change the definition of one or
39 // more classes. While the API supports redefining more than one class
40 // in a single call, in general, the API is discussed in the context of
41 // changing the definition of a single current class to a single new
42 // class. For clarity, the current class is will always be called
43 // "the_class" and the new class will always be called "scratch_class".
44 //
45 // The name "the_class" is used because there is only one structure
46 // that represents a specific class; redefinition does not replace the
47 // structure, but instead replaces parts of the structure. The name
48 // "scratch_class" is used because the structure that represents the
49 // new definition of a specific class is simply used to carry around
50 // the parts of the new definition until they are used to replace the
51 // appropriate parts in the_class. Once redefinition of a class is
52 // complete, scratch_class is thrown away.
53 //
54 //
55 // Implementation Overview:
56 //
57 // The RedefineClasses() API is mostly a wrapper around the VM op that
58 // does the real work. The work is split in varying degrees between
59 // doit_prologue(), doit() and doit_epilogue().
60 //
61 // 1) doit_prologue() is called by the JavaThread on the way to a
62 // safepoint. It does parameter verification and loads scratch_class
63 // which involves:
64 // - parsing the incoming class definition using the_class' class
65 // loader and security context
66 // - linking scratch_class
67 // - merging constant pools and rewriting bytecodes as needed
68 // for the merged constant pool
69 // - verifying the bytecodes in scratch_class
70 // - setting up the constant pool cache and rewriting bytecodes
71 // as needed to use the cache
72 // - finally, scratch_class is compared to the_class to verify
73 // that it is a valid replacement class
74 // - if everything is good, then scratch_class is saved in an
75 // instance field in the VM operation for the doit() call
76 //
77 // Note: A JavaThread must do the above work.
78 //
79 // 2) doit() is called by the VMThread during a safepoint. It installs
80 // the new class definition(s) which involves:
81 // - retrieving the scratch_class from the instance field in the
82 // VM operation
83 // - house keeping (flushing breakpoints and caches, deoptimizing
84 // dependent compiled code)
85 // - replacing parts in the_class with parts from scratch_class
86 // - adding weak reference(s) to track the obsolete but interesting
87 // parts of the_class
88 // - adjusting constant pool caches and vtables in other classes
89 // that refer to methods in the_class. These adjustments use the
90 // SystemDictionary::classes_do() facility which only allows
91 // a helper method to be specified. The interesting parameters
92 // that we would like to pass to the helper method are saved in
93 // static global fields in the VM operation.
94 // - telling the SystemDictionary to notice our changes
95 //
96 // Note: the above work must be done by the VMThread to be safe.
97 //
98 // 3) doit_epilogue() is called by the JavaThread after the VM op
99 // is finished and the safepoint is done. It simply cleans up
100 // memory allocated in doit_prologue() and used in doit().
101 //
102 //
103 // Constant Pool Details:
104 //
105 // When the_class is redefined, we cannot just replace the constant
106 // pool in the_class with the constant pool from scratch_class because
107 // that could confuse obsolete methods that may still be running.
108 // Instead, the constant pool from the_class, old_cp, is merged with
109 // the constant pool from scratch_class, scratch_cp. The resulting
110 // constant pool, merge_cp, replaces old_cp in the_class.
111 //
112 // The key part of any merging algorithm is the entry comparison
113 // function so we have to know the types of entries in a constant pool
114 // in order to merge two of them together. Constant pools can contain
115 // up to 12 different kinds of entries; the JVM_CONSTANT_Unicode entry
116 // is not presently used so we only have to worry about the other 11
117 // entry types. For the purposes of constant pool merging, it is
118 // helpful to know that the 11 entry types fall into 3 different
119 // subtypes: "direct", "indirect" and "double-indirect".
120 //
121 // Direct CP entries contain data and do not contain references to
122 // other CP entries. The following are direct CP entries:
123 // JVM_CONSTANT_{Double,Float,Integer,Long,Utf8}
124 //
125 // Indirect CP entries contain 1 or 2 references to a direct CP entry
126 // and no other data. The following are indirect CP entries:
127 // JVM_CONSTANT_{Class,NameAndType,String}
128 //
129 // Double-indirect CP entries contain two references to indirect CP
130 // entries and no other data. The following are double-indirect CP
131 // entries:
132 // JVM_CONSTANT_{Fieldref,InterfaceMethodref,Methodref}
133 //
134 // When comparing entries between two constant pools, the entry types
135 // are compared first and if they match, then further comparisons are
136 // made depending on the entry subtype. Comparing direct CP entries is
137 // simply a matter of comparing the data associated with each entry.
138 // Comparing both indirect and double-indirect CP entries requires
139 // recursion.
140 //
141 // Fortunately, the recursive combinations are limited because indirect
142 // CP entries can only refer to direct CP entries and double-indirect
143 // CP entries can only refer to indirect CP entries. The following is
144 // an example illustration of the deepest set of indirections needed to
145 // access the data associated with a JVM_CONSTANT_Fieldref entry:
146 //
147 // JVM_CONSTANT_Fieldref {
148 // class_index => JVM_CONSTANT_Class {
149 // name_index => JVM_CONSTANT_Utf8 {
150 // <data-1>
151 // }
152 // }
153 // name_and_type_index => JVM_CONSTANT_NameAndType {
154 // name_index => JVM_CONSTANT_Utf8 {
155 // <data-2>
156 // }
157 // descriptor_index => JVM_CONSTANT_Utf8 {
158 // <data-3>
159 // }
160 // }
161 // }
162 //
163 // The above illustration is not a data structure definition for any
164 // computer language. The curly braces ('{' and '}') are meant to
165 // delimit the context of the "fields" in the CP entry types shown.
166 // Each indirection from the JVM_CONSTANT_Fieldref entry is shown via
167 // "=>", e.g., the class_index is used to indirectly reference a
168 // JVM_CONSTANT_Class entry where the name_index is used to indirectly
169 // reference a JVM_CONSTANT_Utf8 entry which contains the interesting
170 // <data-1>. In order to understand a JVM_CONSTANT_Fieldref entry, we
171 // have to do a total of 5 indirections just to get to the CP entries
172 // that contain the interesting pieces of data and then we have to
173 // fetch the three pieces of data. This means we have to do a total of
174 // (5 + 3) * 2 == 16 dereferences to compare two JVM_CONSTANT_Fieldref
175 // entries.
176 //
177 // Here is the indirection, data and dereference count for each entry
178 // type:
179 //
180 // JVM_CONSTANT_Class 1 indir, 1 data, 2 derefs
181 // JVM_CONSTANT_Double 0 indir, 1 data, 1 deref
182 // JVM_CONSTANT_Fieldref 2 indir, 3 data, 8 derefs
183 // JVM_CONSTANT_Float 0 indir, 1 data, 1 deref
184 // JVM_CONSTANT_Integer 0 indir, 1 data, 1 deref
185 // JVM_CONSTANT_InterfaceMethodref 2 indir, 3 data, 8 derefs
186 // JVM_CONSTANT_Long 0 indir, 1 data, 1 deref
187 // JVM_CONSTANT_Methodref 2 indir, 3 data, 8 derefs
188 // JVM_CONSTANT_NameAndType 1 indir, 2 data, 4 derefs
189 // JVM_CONSTANT_String 1 indir, 1 data, 2 derefs
190 // JVM_CONSTANT_Utf8 0 indir, 1 data, 1 deref
191 //
192 // So different subtypes of CP entries require different amounts of
193 // work for a proper comparison.
194 //
195 // Now that we've talked about the different entry types and how to
196 // compare them we need to get back to merging. This is not a merge in
197 // the "sort -u" sense or even in the "sort" sense. When we merge two
198 // constant pools, we copy all the entries from old_cp to merge_cp,
199 // preserving entry order. Next we append all the unique entries from
200 // scratch_cp to merge_cp and we track the index changes from the
201 // location in scratch_cp to the possibly new location in merge_cp.
202 // When we are done, any obsolete code that is still running that
203 // uses old_cp should not be able to observe any difference if it
204 // were to use merge_cp. As for the new code in scratch_class, it is
205 // modified to use the appropriate index values in merge_cp before it
206 // is used to replace the code in the_class.
207 //
208 // There is one small complication in copying the entries from old_cp
209 // to merge_cp. Two of the CP entry types are special in that they are
210 // lazily resolved. Before explaining the copying complication, we need
211 // to digress into CP entry resolution.
212 //
213 // JVM_CONSTANT_Class entries are present in the class file, but are not
214 // stored in memory as such until they are resolved. The entries are not
215 // resolved unless they are used because resolution is expensive. During class
216 // file parsing the entries are initially stored in memory as
217 // JVM_CONSTANT_ClassIndex and JVM_CONSTANT_StringIndex entries. These special
218 // CP entry types indicate that the JVM_CONSTANT_Class and JVM_CONSTANT_String
219 // entries have been parsed, but the index values in the entries have not been
220 // validated. After the entire constant pool has been parsed, the index
221 // values can be validated and then the entries are converted into
222 // JVM_CONSTANT_UnresolvedClass and JVM_CONSTANT_String
223 // entries. During this conversion process, the UTF8 values that are
224 // indirectly referenced by the JVM_CONSTANT_ClassIndex and
225 // JVM_CONSTANT_StringIndex entries are changed into Symbol*s and the
226 // entries are modified to refer to the Symbol*s. This optimization
227 // eliminates one level of indirection for those two CP entry types and
228 // gets the entries ready for verification. Verification expects to
229 // find JVM_CONSTANT_UnresolvedClass but not JVM_CONSTANT_Class entries.
230 //
231 // Now we can get back to the copying complication. When we copy
232 // entries from old_cp to merge_cp, we have to revert any
233 // JVM_CONSTANT_Class entries to JVM_CONSTANT_UnresolvedClass entries
234 // or verification will fail.
235 //
236 // It is important to explicitly state that the merging algorithm
237 // effectively unresolves JVM_CONSTANT_Class entries that were in the
238 // old_cp when they are changed into JVM_CONSTANT_UnresolvedClass
239 // entries in the merge_cp. This is done both to make verification
240 // happy and to avoid adding more brittleness between RedefineClasses
241 // and the constant pool cache. By allowing the constant pool cache
242 // implementation to (re)resolve JVM_CONSTANT_UnresolvedClass entries
243 // into JVM_CONSTANT_Class entries, we avoid having to embed knowledge
244 // about those algorithms in RedefineClasses.
245 //
246 // Appending unique entries from scratch_cp to merge_cp is straight
247 // forward for direct CP entries and most indirect CP entries. For the
248 // indirect CP entry type JVM_CONSTANT_NameAndType and for the double-
249 // indirect CP entry types, the presence of more than one piece of
250 // interesting data makes appending the entries more complicated.
251 //
252 // For the JVM_CONSTANT_{Double,Float,Integer,Long,Utf8} entry types,
253 // the entry is simply copied from scratch_cp to the end of merge_cp.
254 // If the index in scratch_cp is different than the destination index
255 // in merge_cp, then the change in index value is tracked.
256 //
257 // Note: the above discussion for the direct CP entries also applies
258 // to the JVM_CONSTANT_UnresolvedClass entry types.
259 //
260 // For the JVM_CONSTANT_Class entry types, since there is only
261 // one data element at the end of the recursion, we know that we have
262 // either one or two unique entries. If the JVM_CONSTANT_Utf8 entry is
263 // unique then it is appended to merge_cp before the current entry.
264 // If the JVM_CONSTANT_Utf8 entry is not unique, then the current entry
265 // is updated to refer to the duplicate entry in merge_cp before it is
266 // appended to merge_cp. Again, any changes in index values are tracked
267 // as needed.
268 //
269 // Note: the above discussion for JVM_CONSTANT_Class entry
270 // types is theoretical. Since those entry types have already been
271 // optimized into JVM_CONSTANT_UnresolvedClass entry types,
272 // they are handled as direct CP entries.
273 //
274 // For the JVM_CONSTANT_NameAndType entry type, since there are two
275 // data elements at the end of the recursions, we know that we have
276 // between one and three unique entries. Any unique JVM_CONSTANT_Utf8
277 // entries are appended to merge_cp before the current entry. For any
278 // JVM_CONSTANT_Utf8 entries that are not unique, the current entry is
279 // updated to refer to the duplicate entry in merge_cp before it is
280 // appended to merge_cp. Again, any changes in index values are tracked
281 // as needed.
282 //
283 // For the JVM_CONSTANT_{Fieldref,InterfaceMethodref,Methodref} entry
284 // types, since there are two indirect CP entries and three data
285 // elements at the end of the recursions, we know that we have between
286 // one and six unique entries. See the JVM_CONSTANT_Fieldref diagram
287 // above for an example of all six entries. The uniqueness algorithm
288 // for the JVM_CONSTANT_Class and JVM_CONSTANT_NameAndType entries is
289 // covered above. Any unique entries are appended to merge_cp before
290 // the current entry. For any entries that are not unique, the current
291 // entry is updated to refer to the duplicate entry in merge_cp before
292 // it is appended to merge_cp. Again, any changes in index values are
293 // tracked as needed.
294 //
295 //
296 // Other Details:
297 //
298 // Details for other parts of RedefineClasses need to be written.
299 // This is a placeholder section.
300 //
301 //
302 // Open Issues (in no particular order):
303 //
304 // - How do we serialize the RedefineClasses() API without deadlocking?
305 //
306 // - SystemDictionary::parse_stream() was called with a NULL protection
307 // domain since the initial version. This has been changed to pass
308 // the_class->protection_domain(). This change has been tested with
309 // all NSK tests and nothing broke, but what will adding it now break
310 // in ways that we don't test?
311 //
312 // - GenerateOopMap::rewrite_load_or_store() has a comment in its
313 // (indirect) use of the Relocator class that the max instruction
314 // size is 4 bytes. goto_w and jsr_w are 5 bytes and wide/iinc is
315 // 6 bytes. Perhaps Relocator only needs a 4 byte buffer to do
316 // what it does to the bytecodes. More investigation is needed.
317 //
318 // - How do we know if redefine_single_class() and the guts of
319 // InstanceKlass are out of sync? I don't think this can be
320 // automated, but we should probably order the work in
321 // redefine_single_class() to match the order of field
322 // definitions in InstanceKlass. We also need to add some
323 // comments about keeping things in sync.
324 //
325 // - set_new_constant_pool() is huge and we should consider refactoring
326 // it into smaller chunks of work.
327 //
328 // - The exception table update code in set_new_constant_pool() defines
329 // const values that are also defined in a local context elsewhere.
330 // The same literal values are also used in elsewhere. We need to
331 // coordinate a cleanup of these constants with Runtime.
332 //
334 class VM_RedefineClasses: public VM_Operation {
335 private:
336 // These static fields are needed by SystemDictionary::classes_do()
337 // facility and the adjust_cpool_cache_and_vtable() helper:
338 static Array<Method*>* _old_methods;
339 static Array<Method*>* _new_methods;
340 static Method** _matching_old_methods;
341 static Method** _matching_new_methods;
342 static Method** _deleted_methods;
343 static Method** _added_methods;
344 static int _matching_methods_length;
345 static int _deleted_methods_length;
346 static int _added_methods_length;
347 static Klass* _the_class_oop;
349 // The instance fields are used to pass information from
350 // doit_prologue() to doit() and doit_epilogue().
351 jint _class_count;
352 const jvmtiClassDefinition *_class_defs; // ptr to _class_count defs
354 // This operation is used by both RedefineClasses and
355 // RetransformClasses. Indicate which.
356 JvmtiClassLoadKind _class_load_kind;
358 // _index_map_count is just an optimization for knowing if
359 // _index_map_p contains any entries.
360 int _index_map_count;
361 intArray * _index_map_p;
362 // ptr to _class_count scratch_classes
363 Klass** _scratch_classes;
364 jvmtiError _res;
366 // Performance measurement support. These timers do not cover all
367 // the work done for JVM/TI RedefineClasses() but they do cover
368 // the heavy lifting.
369 elapsedTimer _timer_rsc_phase1;
370 elapsedTimer _timer_rsc_phase2;
371 elapsedTimer _timer_vm_op_prologue;
373 // These routines are roughly in call order unless otherwise noted.
375 // Load the caller's new class definition(s) into _scratch_classes.
376 // Constant pool merging work is done here as needed. Also calls
377 // compare_and_normalize_class_versions() to verify the class
378 // definition(s).
379 jvmtiError load_new_class_versions(TRAPS);
381 // Verify that the caller provided class definition(s) that meet
382 // the restrictions of RedefineClasses. Normalize the order of
383 // overloaded methods as needed.
384 jvmtiError compare_and_normalize_class_versions(
385 instanceKlassHandle the_class, instanceKlassHandle scratch_class);
387 // Swap annotations[i] with annotations[j]
388 // Used by compare_and_normalize_class_versions() when normalizing
389 // overloaded methods or changing idnum as when adding or deleting methods.
390 void swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class, TRAPS);
392 // Figure out which new methods match old methods in name and signature,
393 // which methods have been added, and which are no longer present
394 void compute_added_deleted_matching_methods();
396 // Change jmethodIDs to point to the new methods
397 void update_jmethod_ids();
399 // In addition to marking methods as obsolete, this routine
400 // records which methods are EMCP (Equivalent Module Constant
401 // Pool) in the emcp_methods BitMap and returns the number of
402 // EMCP methods via emcp_method_count_p. This information is
403 // used when information about the previous version of the_class
404 // is squirreled away.
405 void check_methods_and_mark_as_obsolete(BitMap *emcp_methods,
406 int * emcp_method_count_p);
407 void transfer_old_native_function_registrations(instanceKlassHandle the_class);
409 // Unevolving classes may point to methods of the_class directly
410 // from their constant pool caches, itables, and/or vtables. We
411 // use the SystemDictionary::classes_do() facility and this helper
412 // to fix up these pointers.
413 static void adjust_cpool_cache_and_vtable(Klass* k_oop, ClassLoaderData* initiating_loader, TRAPS);
414 static void adjust_array_vtable(Klass* k_oop);
416 // Install the redefinition of a class
417 void redefine_single_class(jclass the_jclass,
418 Klass* scratch_class_oop, TRAPS);
420 // Increment the classRedefinedCount field in the specific InstanceKlass
421 // and in all direct and indirect subclasses.
422 void increment_class_counter(InstanceKlass *ik, TRAPS);
424 // Support for constant pool merging (these routines are in alpha
425 // order):
426 void append_entry(constantPoolHandle scratch_cp, int scratch_i,
427 constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS);
428 int find_new_index(int old_index);
429 bool is_unresolved_class_mismatch(constantPoolHandle cp1, int index1,
430 constantPoolHandle cp2, int index2);
431 void map_index(constantPoolHandle scratch_cp, int old_index, int new_index);
432 bool merge_constant_pools(constantPoolHandle old_cp,
433 constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
434 int *merge_cp_length_p, TRAPS);
435 jvmtiError merge_cp_and_rewrite(instanceKlassHandle the_class,
436 instanceKlassHandle scratch_class, TRAPS);
437 u2 rewrite_cp_ref_in_annotation_data(
438 AnnotationArray* annotations_typeArray, int &byte_i_ref,
439 const char * trace_mesg, TRAPS);
440 bool rewrite_cp_refs(instanceKlassHandle scratch_class, TRAPS);
441 bool rewrite_cp_refs_in_annotation_struct(
442 AnnotationArray* class_annotations, int &byte_i_ref, TRAPS);
443 bool rewrite_cp_refs_in_annotations_typeArray(
444 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS);
445 bool rewrite_cp_refs_in_class_annotations(
446 instanceKlassHandle scratch_class, TRAPS);
447 bool rewrite_cp_refs_in_element_value(
448 AnnotationArray* class_annotations, int &byte_i_ref, TRAPS);
449 bool rewrite_cp_refs_in_fields_annotations(
450 instanceKlassHandle scratch_class, TRAPS);
451 void rewrite_cp_refs_in_method(methodHandle method,
452 methodHandle * new_method_p, TRAPS);
453 bool rewrite_cp_refs_in_methods(instanceKlassHandle scratch_class, TRAPS);
454 bool rewrite_cp_refs_in_methods_annotations(
455 instanceKlassHandle scratch_class, TRAPS);
456 bool rewrite_cp_refs_in_methods_default_annotations(
457 instanceKlassHandle scratch_class, TRAPS);
458 bool rewrite_cp_refs_in_methods_parameter_annotations(
459 instanceKlassHandle scratch_class, TRAPS);
460 void rewrite_cp_refs_in_stack_map_table(methodHandle method, TRAPS);
461 void rewrite_cp_refs_in_verification_type_info(
462 address& stackmap_addr_ref, address stackmap_end, u2 frame_i,
463 u1 frame_size, TRAPS);
464 void set_new_constant_pool(ClassLoaderData* loader_data,
465 instanceKlassHandle scratch_class,
466 constantPoolHandle scratch_cp, int scratch_cp_length, TRAPS);
468 void flush_dependent_code(instanceKlassHandle k_h, TRAPS);
470 static void check_class(Klass* k_oop, ClassLoaderData* initiating_loader, TRAPS) PRODUCT_RETURN;
472 static void dump_methods() PRODUCT_RETURN;
474 public:
475 VM_RedefineClasses(jint class_count,
476 const jvmtiClassDefinition *class_defs,
477 JvmtiClassLoadKind class_load_kind);
478 VMOp_Type type() const { return VMOp_RedefineClasses; }
479 bool doit_prologue();
480 void doit();
481 void doit_epilogue();
483 bool allow_nested_vm_operations() const { return true; }
484 jvmtiError check_error() { return _res; }
486 // Modifiable test must be shared between IsModifiableClass query
487 // and redefine implementation
488 static bool is_modifiable_class(oop klass_mirror);
489 };
490 #endif // SHARE_VM_PRIMS_JVMTIREDEFINECLASSES_HPP