Tue, 11 Sep 2012 14:59:23 +0200
7197350: NPG: jvmtiHeapReferenceCallback receives incorrect reference_kind for system class roots
Summary: Fix the iteration over the system classes and report the correct reference kind.
Reviewed-by: coleenp, rbackman
1 /*
2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 * accompanied this code).
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25 #ifndef SHARE_VM_MEMORY_ITERATOR_HPP
26 #define SHARE_VM_MEMORY_ITERATOR_HPP
28 #include "memory/allocation.hpp"
29 #include "memory/memRegion.hpp"
30 #include "runtime/prefetch.hpp"
31 #include "utilities/top.hpp"
33 // The following classes are C++ `closures` for iterating over objects, roots and spaces
35 class CodeBlob;
36 class nmethod;
37 class ReferenceProcessor;
38 class DataLayout;
39 class KlassClosure;
40 class ClassLoaderData;
42 // Closure provides abortability.
44 class Closure : public StackObj {
45 protected:
46 bool _abort;
47 void set_abort() { _abort = true; }
48 public:
49 Closure() : _abort(false) {}
50 // A subtype can use this mechanism to indicate to some iterator mapping
51 // functions that the iteration should cease.
52 bool abort() { return _abort; }
53 void clear_abort() { _abort = false; }
54 };
56 // OopClosure is used for iterating through references to Java objects.
58 class OopClosure : public Closure {
59 public:
60 virtual void do_oop(oop* o) = 0;
61 virtual void do_oop_v(oop* o) { do_oop(o); }
62 virtual void do_oop(narrowOop* o) = 0;
63 virtual void do_oop_v(narrowOop* o) { do_oop(o); }
64 };
66 // ExtendedOopClosure adds extra code to be run during oop iterations.
67 // This is needed by the GC and is extracted to a separate type to not
68 // pollute the OopClosure interface.
69 class ExtendedOopClosure : public OopClosure {
70 public:
71 ReferenceProcessor* _ref_processor;
72 ExtendedOopClosure(ReferenceProcessor* rp) : _ref_processor(rp) { }
73 ExtendedOopClosure() : OopClosure(), _ref_processor(NULL) { }
75 // If the do_metadata functions return "true",
76 // we invoke the following when running oop_iterate():
77 //
78 // 1) do_klass on the header klass pointer.
79 // 2) do_klass on the klass pointer in the mirrors.
80 // 3) do_class_loader_data on the class loader data in class loaders.
81 //
82 // The virtual (without suffix) and the non-virtual (with _nv suffix) need
83 // to be updated together, or else the devirtualization will break.
84 //
85 // Providing default implementations of the _nv functions unfortunately
86 // removes the compile-time safeness, but reduces the clutter for the
87 // ExtendedOopClosures that don't need to walk the metadata. Currently,
88 // only CMS needs these.
90 virtual bool do_metadata() { return do_metadata_nv(); }
91 bool do_metadata_v() { return do_metadata(); }
92 bool do_metadata_nv() { return false; }
94 virtual void do_klass(Klass* k) { do_klass_nv(k); }
95 void do_klass_v(Klass* k) { do_klass(k); }
96 void do_klass_nv(Klass* k) { ShouldNotReachHere(); }
98 virtual void do_class_loader_data(ClassLoaderData* cld) { ShouldNotReachHere(); }
100 // Controls how prefetching is done for invocations of this closure.
101 Prefetch::style prefetch_style() { // Note that this is non-virtual.
102 return Prefetch::do_none;
103 }
105 // True iff this closure may be safely applied more than once to an oop
106 // location without an intervening "major reset" (like the end of a GC).
107 virtual bool idempotent() { return false; }
108 virtual bool apply_to_weak_ref_discovered_field() { return false; }
109 };
111 // Wrapper closure only used to implement oop_iterate_no_header().
112 class NoHeaderExtendedOopClosure : public ExtendedOopClosure {
113 OopClosure* _wrapped_closure;
114 public:
115 NoHeaderExtendedOopClosure(OopClosure* cl) : _wrapped_closure(cl) {}
116 // Warning: this calls the virtual version do_oop in the the wrapped closure.
117 void do_oop_nv(oop* p) { _wrapped_closure->do_oop(p); }
118 void do_oop_nv(narrowOop* p) { _wrapped_closure->do_oop(p); }
120 void do_oop(oop* p) { assert(false, "Only the _nv versions should be used");
121 _wrapped_closure->do_oop(p); }
122 void do_oop(narrowOop* p) { assert(false, "Only the _nv versions should be used");
123 _wrapped_closure->do_oop(p);}
124 };
126 class KlassClosure : public Closure {
127 public:
128 virtual void do_klass(Klass* k) = 0;
129 };
131 class KlassToOopClosure : public KlassClosure {
132 OopClosure* _oop_closure;
133 public:
134 KlassToOopClosure(OopClosure* oop_closure) : _oop_closure(oop_closure) {}
135 virtual void do_klass(Klass* k);
136 };
138 // ObjectClosure is used for iterating through an object space
140 class ObjectClosure : public Closure {
141 public:
142 // Called for each object.
143 virtual void do_object(oop obj) = 0;
144 };
147 class BoolObjectClosure : public ObjectClosure {
148 public:
149 virtual bool do_object_b(oop obj) = 0;
150 };
152 // Applies an oop closure to all ref fields in objects iterated over in an
153 // object iteration.
154 class ObjectToOopClosure: public ObjectClosure {
155 ExtendedOopClosure* _cl;
156 public:
157 void do_object(oop obj);
158 ObjectToOopClosure(ExtendedOopClosure* cl) : _cl(cl) {}
159 };
161 // A version of ObjectClosure with "memory" (see _previous_address below)
162 class UpwardsObjectClosure: public BoolObjectClosure {
163 HeapWord* _previous_address;
164 public:
165 UpwardsObjectClosure() : _previous_address(NULL) { }
166 void set_previous(HeapWord* addr) { _previous_address = addr; }
167 HeapWord* previous() { return _previous_address; }
168 // A return value of "true" can be used by the caller to decide
169 // if this object's end should *NOT* be recorded in
170 // _previous_address above.
171 virtual bool do_object_bm(oop obj, MemRegion mr) = 0;
172 };
174 // A version of ObjectClosure that is expected to be robust
175 // in the face of possibly uninitialized objects.
176 class ObjectClosureCareful : public ObjectClosure {
177 public:
178 virtual size_t do_object_careful_m(oop p, MemRegion mr) = 0;
179 virtual size_t do_object_careful(oop p) = 0;
180 };
182 // The following are used in CompactibleFreeListSpace and
183 // ConcurrentMarkSweepGeneration.
185 // Blk closure (abstract class)
186 class BlkClosure : public StackObj {
187 public:
188 virtual size_t do_blk(HeapWord* addr) = 0;
189 };
191 // A version of BlkClosure that is expected to be robust
192 // in the face of possibly uninitialized objects.
193 class BlkClosureCareful : public BlkClosure {
194 public:
195 size_t do_blk(HeapWord* addr) {
196 guarantee(false, "call do_blk_careful instead");
197 return 0;
198 }
199 virtual size_t do_blk_careful(HeapWord* addr) = 0;
200 };
202 // SpaceClosure is used for iterating over spaces
204 class Space;
205 class CompactibleSpace;
207 class SpaceClosure : public StackObj {
208 public:
209 // Called for each space
210 virtual void do_space(Space* s) = 0;
211 };
213 class CompactibleSpaceClosure : public StackObj {
214 public:
215 // Called for each compactible space
216 virtual void do_space(CompactibleSpace* s) = 0;
217 };
220 // CodeBlobClosure is used for iterating through code blobs
221 // in the code cache or on thread stacks
223 class CodeBlobClosure : public Closure {
224 public:
225 // Called for each code blob.
226 virtual void do_code_blob(CodeBlob* cb) = 0;
227 };
230 class MarkingCodeBlobClosure : public CodeBlobClosure {
231 public:
232 // Called for each code blob, but at most once per unique blob.
233 virtual void do_newly_marked_nmethod(nmethod* nm) = 0;
235 virtual void do_code_blob(CodeBlob* cb);
236 // = { if (!nmethod(cb)->test_set_oops_do_mark()) do_newly_marked_nmethod(cb); }
238 class MarkScope : public StackObj {
239 protected:
240 bool _active;
241 public:
242 MarkScope(bool activate = true);
243 // = { if (active) nmethod::oops_do_marking_prologue(); }
244 ~MarkScope();
245 // = { if (active) nmethod::oops_do_marking_epilogue(); }
246 };
247 };
250 // Applies an oop closure to all ref fields in code blobs
251 // iterated over in an object iteration.
252 class CodeBlobToOopClosure: public MarkingCodeBlobClosure {
253 OopClosure* _cl;
254 bool _do_marking;
255 public:
256 virtual void do_newly_marked_nmethod(nmethod* cb);
257 // = { cb->oops_do(_cl); }
258 virtual void do_code_blob(CodeBlob* cb);
259 // = { if (_do_marking) super::do_code_blob(cb); else cb->oops_do(_cl); }
260 CodeBlobToOopClosure(OopClosure* cl, bool do_marking)
261 : _cl(cl), _do_marking(do_marking) {}
262 };
266 // MonitorClosure is used for iterating over monitors in the monitors cache
268 class ObjectMonitor;
270 class MonitorClosure : public StackObj {
271 public:
272 // called for each monitor in cache
273 virtual void do_monitor(ObjectMonitor* m) = 0;
274 };
276 // A closure that is applied without any arguments.
277 class VoidClosure : public StackObj {
278 public:
279 // I would have liked to declare this a pure virtual, but that breaks
280 // in mysterious ways, for unknown reasons.
281 virtual void do_void();
282 };
285 // YieldClosure is intended for use by iteration loops
286 // to incrementalize their work, allowing interleaving
287 // of an interruptable task so as to allow other
288 // threads to run (which may not otherwise be able to access
289 // exclusive resources, for instance). Additionally, the
290 // closure also allows for aborting an ongoing iteration
291 // by means of checking the return value from the polling
292 // call.
293 class YieldClosure : public StackObj {
294 public:
295 virtual bool should_return() = 0;
296 };
298 // Abstract closure for serializing data (read or write).
300 class SerializeClosure : public Closure {
301 public:
302 // Return bool indicating whether closure implements read or write.
303 virtual bool reading() const = 0;
305 // Read/write the void pointer pointed to by p.
306 virtual void do_ptr(void** p) = 0;
308 // Read/write the region specified.
309 virtual void do_region(u_char* start, size_t size) = 0;
311 // Check/write the tag. If reading, then compare the tag against
312 // the passed in value and fail is they don't match. This allows
313 // for verification that sections of the serialized data are of the
314 // correct length.
315 virtual void do_tag(int tag) = 0;
316 };
318 class SymbolClosure : public StackObj {
319 public:
320 virtual void do_symbol(Symbol**) = 0;
322 // Clear LSB in symbol address; it can be set by CPSlot.
323 static Symbol* load_symbol(Symbol** p) {
324 return (Symbol*)(intptr_t(*p) & ~1);
325 }
327 // Store symbol, adjusting new pointer if the original pointer was adjusted
328 // (symbol references in constant pool slots have their LSB set to 1).
329 static void store_symbol(Symbol** p, Symbol* sym) {
330 *p = (Symbol*)(intptr_t(sym) | (intptr_t(*p) & 1));
331 }
332 };
334 #endif // SHARE_VM_MEMORY_ITERATOR_HPP