Wed, 02 Jan 2013 20:28:09 -0500
8005494: SIGSEGV in Rewriter::relocate_and_link() when testing Weblogic with CompressedOops and KlassPtrs
Summary: Relocate functions with jsr's when rewriting so not repeated after reading shared archive
Reviewed-by: twisti, jrose
1 /*
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25 #include "precompiled.hpp"
26 #include "interpreter/bytecodes.hpp"
27 #include "interpreter/interpreter.hpp"
28 #include "interpreter/rewriter.hpp"
29 #include "memory/gcLocker.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/generateOopMap.hpp"
32 #include "prims/methodHandles.hpp"
34 // Computes a CPC map (new_index -> original_index) for constant pool entries
35 // that are referred to by the interpreter at runtime via the constant pool cache.
36 // Also computes a CP map (original_index -> new_index).
37 // Marks entries in CP which require additional processing.
38 void Rewriter::compute_index_maps() {
39 const int length = _pool->length();
40 init_maps(length);
41 bool saw_mh_symbol = false;
42 for (int i = 0; i < length; i++) {
43 int tag = _pool->tag_at(i).value();
44 switch (tag) {
45 case JVM_CONSTANT_InterfaceMethodref:
46 case JVM_CONSTANT_Fieldref : // fall through
47 case JVM_CONSTANT_Methodref : // fall through
48 add_cp_cache_entry(i);
49 break;
50 case JVM_CONSTANT_String:
51 case JVM_CONSTANT_Object:
52 case JVM_CONSTANT_MethodHandle : // fall through
53 case JVM_CONSTANT_MethodType : // fall through
54 add_resolved_references_entry(i);
55 break;
56 case JVM_CONSTANT_Utf8:
57 if (_pool->symbol_at(i) == vmSymbols::java_lang_invoke_MethodHandle())
58 saw_mh_symbol = true;
59 break;
60 }
61 }
63 // Record limits of resolved reference map for constant pool cache indices
64 record_map_limits();
66 guarantee((int)_cp_cache_map.length()-1 <= (int)((u2)-1),
67 "all cp cache indexes fit in a u2");
69 if (saw_mh_symbol)
70 _method_handle_invokers.initialize(length, (int)0);
71 }
73 // Unrewrite the bytecodes if an error occurs.
74 void Rewriter::restore_bytecodes() {
75 int len = _methods->length();
77 for (int i = len-1; i >= 0; i--) {
78 Method* method = _methods->at(i);
79 scan_method(method, true);
80 }
81 }
83 // Creates a constant pool cache given a CPC map
84 void Rewriter::make_constant_pool_cache(TRAPS) {
85 const int length = _cp_cache_map.length();
86 ClassLoaderData* loader_data = _pool->pool_holder()->class_loader_data();
87 ConstantPoolCache* cache =
88 ConstantPoolCache::allocate(loader_data, length, CHECK);
90 // initialize object cache in constant pool
91 _pool->initialize_resolved_references(loader_data, _resolved_references_map,
92 _resolved_reference_limit,
93 CHECK);
95 No_Safepoint_Verifier nsv;
96 cache->initialize(_cp_cache_map, _invokedynamic_references_map);
97 _pool->set_cache(cache);
98 cache->set_constant_pool(_pool());
99 }
103 // The new finalization semantics says that registration of
104 // finalizable objects must be performed on successful return from the
105 // Object.<init> constructor. We could implement this trivially if
106 // <init> were never rewritten but since JVMTI allows this to occur, a
107 // more complicated solution is required. A special return bytecode
108 // is used only by Object.<init> to signal the finalization
109 // registration point. Additionally local 0 must be preserved so it's
110 // available to pass to the registration function. For simplicty we
111 // require that local 0 is never overwritten so it's available as an
112 // argument for registration.
114 void Rewriter::rewrite_Object_init(methodHandle method, TRAPS) {
115 RawBytecodeStream bcs(method);
116 while (!bcs.is_last_bytecode()) {
117 Bytecodes::Code opcode = bcs.raw_next();
118 switch (opcode) {
119 case Bytecodes::_return: *bcs.bcp() = Bytecodes::_return_register_finalizer; break;
121 case Bytecodes::_istore:
122 case Bytecodes::_lstore:
123 case Bytecodes::_fstore:
124 case Bytecodes::_dstore:
125 case Bytecodes::_astore:
126 if (bcs.get_index() != 0) continue;
128 // fall through
129 case Bytecodes::_istore_0:
130 case Bytecodes::_lstore_0:
131 case Bytecodes::_fstore_0:
132 case Bytecodes::_dstore_0:
133 case Bytecodes::_astore_0:
134 THROW_MSG(vmSymbols::java_lang_IncompatibleClassChangeError(),
135 "can't overwrite local 0 in Object.<init>");
136 break;
137 }
138 }
139 }
142 // Rewrite a classfile-order CP index into a native-order CPC index.
143 void Rewriter::rewrite_member_reference(address bcp, int offset, bool reverse) {
144 address p = bcp + offset;
145 if (!reverse) {
146 int cp_index = Bytes::get_Java_u2(p);
147 int cache_index = cp_entry_to_cp_cache(cp_index);
148 Bytes::put_native_u2(p, cache_index);
149 if (!_method_handle_invokers.is_empty())
150 maybe_rewrite_invokehandle(p - 1, cp_index, cache_index, reverse);
151 } else {
152 int cache_index = Bytes::get_native_u2(p);
153 int pool_index = cp_cache_entry_pool_index(cache_index);
154 Bytes::put_Java_u2(p, pool_index);
155 if (!_method_handle_invokers.is_empty())
156 maybe_rewrite_invokehandle(p - 1, pool_index, cache_index, reverse);
157 }
158 }
161 // Adjust the invocation bytecode for a signature-polymorphic method (MethodHandle.invoke, etc.)
162 void Rewriter::maybe_rewrite_invokehandle(address opc, int cp_index, int cache_index, bool reverse) {
163 if (!reverse) {
164 if ((*opc) == (u1)Bytecodes::_invokevirtual ||
165 // allow invokespecial as an alias, although it would be very odd:
166 (*opc) == (u1)Bytecodes::_invokespecial) {
167 assert(_pool->tag_at(cp_index).is_method(), "wrong index");
168 // Determine whether this is a signature-polymorphic method.
169 if (cp_index >= _method_handle_invokers.length()) return;
170 int status = _method_handle_invokers[cp_index];
171 assert(status >= -1 && status <= 1, "oob tri-state");
172 if (status == 0) {
173 if (_pool->klass_ref_at_noresolve(cp_index) == vmSymbols::java_lang_invoke_MethodHandle() &&
174 MethodHandles::is_signature_polymorphic_name(SystemDictionary::MethodHandle_klass(),
175 _pool->name_ref_at(cp_index))) {
176 // we may need a resolved_refs entry for the appendix
177 add_invokedynamic_resolved_references_entries(cp_index, cache_index);
178 status = +1;
179 } else {
180 status = -1;
181 }
182 _method_handle_invokers[cp_index] = status;
183 }
184 // We use a special internal bytecode for such methods (if non-static).
185 // The basic reason for this is that such methods need an extra "appendix" argument
186 // to transmit the call site's intended call type.
187 if (status > 0) {
188 (*opc) = (u1)Bytecodes::_invokehandle;
189 }
190 }
191 } else {
192 // Do not need to look at cp_index.
193 if ((*opc) == (u1)Bytecodes::_invokehandle) {
194 (*opc) = (u1)Bytecodes::_invokevirtual;
195 // Ignore corner case of original _invokespecial instruction.
196 // This is safe because (a) the signature polymorphic method was final, and
197 // (b) the implementation of MethodHandle will not call invokespecial on it.
198 }
199 }
200 }
203 void Rewriter::rewrite_invokedynamic(address bcp, int offset, bool reverse) {
204 address p = bcp + offset;
205 assert(p[-1] == Bytecodes::_invokedynamic, "not invokedynamic bytecode");
206 if (!reverse) {
207 int cp_index = Bytes::get_Java_u2(p);
208 int cache_index = add_invokedynamic_cp_cache_entry(cp_index);
209 add_invokedynamic_resolved_references_entries(cp_index, cache_index);
210 // Replace the trailing four bytes with a CPC index for the dynamic
211 // call site. Unlike other CPC entries, there is one per bytecode,
212 // not just one per distinct CP entry. In other words, the
213 // CPC-to-CP relation is many-to-one for invokedynamic entries.
214 // This means we must use a larger index size than u2 to address
215 // all these entries. That is the main reason invokedynamic
216 // must have a five-byte instruction format. (Of course, other JVM
217 // implementations can use the bytes for other purposes.)
218 Bytes::put_native_u4(p, ConstantPool::encode_invokedynamic_index(cache_index));
219 // Note: We use native_u4 format exclusively for 4-byte indexes.
220 } else {
221 // callsite index
222 int cache_index = ConstantPool::decode_invokedynamic_index(
223 Bytes::get_native_u4(p));
224 int cp_index = cp_cache_entry_pool_index(cache_index);
225 assert(_pool->tag_at(cp_index).is_invoke_dynamic(), "wrong index");
226 // zero out 4 bytes
227 Bytes::put_Java_u4(p, 0);
228 Bytes::put_Java_u2(p, cp_index);
229 }
230 }
233 // Rewrite some ldc bytecodes to _fast_aldc
234 void Rewriter::maybe_rewrite_ldc(address bcp, int offset, bool is_wide,
235 bool reverse) {
236 if (!reverse) {
237 assert((*bcp) == (is_wide ? Bytecodes::_ldc_w : Bytecodes::_ldc), "not ldc bytecode");
238 address p = bcp + offset;
239 int cp_index = is_wide ? Bytes::get_Java_u2(p) : (u1)(*p);
240 constantTag tag = _pool->tag_at(cp_index).value();
241 if (tag.is_method_handle() || tag.is_method_type() || tag.is_string() || tag.is_object()) {
242 int ref_index = cp_entry_to_resolved_references(cp_index);
243 if (is_wide) {
244 (*bcp) = Bytecodes::_fast_aldc_w;
245 assert(ref_index == (u2)ref_index, "index overflow");
246 Bytes::put_native_u2(p, ref_index);
247 } else {
248 (*bcp) = Bytecodes::_fast_aldc;
249 assert(ref_index == (u1)ref_index, "index overflow");
250 (*p) = (u1)ref_index;
251 }
252 }
253 } else {
254 Bytecodes::Code rewritten_bc =
255 (is_wide ? Bytecodes::_fast_aldc_w : Bytecodes::_fast_aldc);
256 if ((*bcp) == rewritten_bc) {
257 address p = bcp + offset;
258 int ref_index = is_wide ? Bytes::get_native_u2(p) : (u1)(*p);
259 int pool_index = resolved_references_entry_to_pool_index(ref_index);
260 if (is_wide) {
261 (*bcp) = Bytecodes::_ldc_w;
262 assert(pool_index == (u2)pool_index, "index overflow");
263 Bytes::put_Java_u2(p, pool_index);
264 } else {
265 (*bcp) = Bytecodes::_ldc;
266 assert(pool_index == (u1)pool_index, "index overflow");
267 (*p) = (u1)pool_index;
268 }
269 }
270 }
271 }
274 // Rewrites a method given the index_map information
275 void Rewriter::scan_method(Method* method, bool reverse) {
277 int nof_jsrs = 0;
278 bool has_monitor_bytecodes = false;
280 {
281 // We cannot tolerate a GC in this block, because we've
282 // cached the bytecodes in 'code_base'. If the Method*
283 // moves, the bytecodes will also move.
284 No_Safepoint_Verifier nsv;
285 Bytecodes::Code c;
287 // Bytecodes and their length
288 const address code_base = method->code_base();
289 const int code_length = method->code_size();
291 int bc_length;
292 for (int bci = 0; bci < code_length; bci += bc_length) {
293 address bcp = code_base + bci;
294 int prefix_length = 0;
295 c = (Bytecodes::Code)(*bcp);
297 // Since we have the code, see if we can get the length
298 // directly. Some more complicated bytecodes will report
299 // a length of zero, meaning we need to make another method
300 // call to calculate the length.
301 bc_length = Bytecodes::length_for(c);
302 if (bc_length == 0) {
303 bc_length = Bytecodes::length_at(method, bcp);
305 // length_at will put us at the bytecode after the one modified
306 // by 'wide'. We don't currently examine any of the bytecodes
307 // modified by wide, but in case we do in the future...
308 if (c == Bytecodes::_wide) {
309 prefix_length = 1;
310 c = (Bytecodes::Code)bcp[1];
311 }
312 }
314 assert(bc_length != 0, "impossible bytecode length");
316 switch (c) {
317 case Bytecodes::_lookupswitch : {
318 #ifndef CC_INTERP
319 Bytecode_lookupswitch bc(method, bcp);
320 (*bcp) = (
321 bc.number_of_pairs() < BinarySwitchThreshold
322 ? Bytecodes::_fast_linearswitch
323 : Bytecodes::_fast_binaryswitch
324 );
325 #endif
326 break;
327 }
328 case Bytecodes::_fast_linearswitch:
329 case Bytecodes::_fast_binaryswitch: {
330 #ifndef CC_INTERP
331 (*bcp) = Bytecodes::_lookupswitch;
332 #endif
333 break;
334 }
335 case Bytecodes::_getstatic : // fall through
336 case Bytecodes::_putstatic : // fall through
337 case Bytecodes::_getfield : // fall through
338 case Bytecodes::_putfield : // fall through
339 case Bytecodes::_invokevirtual : // fall through
340 case Bytecodes::_invokespecial : // fall through
341 case Bytecodes::_invokestatic :
342 case Bytecodes::_invokeinterface:
343 case Bytecodes::_invokehandle : // if reverse=true
344 rewrite_member_reference(bcp, prefix_length+1, reverse);
345 break;
346 case Bytecodes::_invokedynamic:
347 rewrite_invokedynamic(bcp, prefix_length+1, reverse);
348 break;
349 case Bytecodes::_ldc:
350 case Bytecodes::_fast_aldc: // if reverse=true
351 maybe_rewrite_ldc(bcp, prefix_length+1, false, reverse);
352 break;
353 case Bytecodes::_ldc_w:
354 case Bytecodes::_fast_aldc_w: // if reverse=true
355 maybe_rewrite_ldc(bcp, prefix_length+1, true, reverse);
356 break;
357 case Bytecodes::_jsr : // fall through
358 case Bytecodes::_jsr_w : nof_jsrs++; break;
359 case Bytecodes::_monitorenter : // fall through
360 case Bytecodes::_monitorexit : has_monitor_bytecodes = true; break;
361 }
362 }
363 }
365 // Update access flags
366 if (has_monitor_bytecodes) {
367 method->set_has_monitor_bytecodes();
368 }
370 // The present of a jsr bytecode implies that the method might potentially
371 // have to be rewritten, so we run the oopMapGenerator on the method
372 if (nof_jsrs > 0) {
373 method->set_has_jsrs();
374 // Second pass will revisit this method.
375 assert(method->has_jsrs(), "didn't we just set this?");
376 }
377 }
379 // After constant pool is created, revisit methods containing jsrs.
380 methodHandle Rewriter::rewrite_jsrs(methodHandle method, TRAPS) {
381 ResourceMark rm(THREAD);
382 ResolveOopMapConflicts romc(method);
383 methodHandle original_method = method;
384 method = romc.do_potential_rewrite(CHECK_(methodHandle()));
385 // Update monitor matching info.
386 if (romc.monitor_safe()) {
387 method->set_guaranteed_monitor_matching();
388 }
390 return method;
391 }
393 void Rewriter::rewrite(instanceKlassHandle klass, TRAPS) {
394 ResourceMark rm(THREAD);
395 Rewriter rw(klass, klass->constants(), klass->methods(), CHECK);
396 // (That's all, folks.)
397 }
400 Rewriter::Rewriter(instanceKlassHandle klass, constantPoolHandle cpool, Array<Method*>* methods, TRAPS)
401 : _klass(klass),
402 _pool(cpool),
403 _methods(methods)
404 {
405 assert(_pool->cache() == NULL, "constant pool cache must not be set yet");
407 // determine index maps for Method* rewriting
408 compute_index_maps();
410 if (RegisterFinalizersAtInit && _klass->name() == vmSymbols::java_lang_Object()) {
411 bool did_rewrite = false;
412 int i = _methods->length();
413 while (i-- > 0) {
414 Method* method = _methods->at(i);
415 if (method->intrinsic_id() == vmIntrinsics::_Object_init) {
416 // rewrite the return bytecodes of Object.<init> to register the
417 // object for finalization if needed.
418 methodHandle m(THREAD, method);
419 rewrite_Object_init(m, CHECK);
420 did_rewrite = true;
421 break;
422 }
423 }
424 assert(did_rewrite, "must find Object::<init> to rewrite it");
425 }
427 // rewrite methods, in two passes
428 int len = _methods->length();
430 for (int i = len-1; i >= 0; i--) {
431 Method* method = _methods->at(i);
432 scan_method(method);
433 }
435 // allocate constant pool cache, now that we've seen all the bytecodes
436 make_constant_pool_cache(THREAD);
438 // Restore bytecodes to their unrewritten state if there are exceptions
439 // rewriting bytecodes or allocating the cpCache
440 if (HAS_PENDING_EXCEPTION) {
441 restore_bytecodes();
442 return;
443 }
445 // Relocate after everything, but still do this under the is_rewritten flag,
446 // so methods with jsrs in custom class lists in aren't attempted to be
447 // rewritten in the RO section of the shared archive.
448 // Relocated bytecodes don't have to be restored, only the cp cache entries
449 for (int i = len-1; i >= 0; i--) {
450 methodHandle m(THREAD, _methods->at(i));
452 if (m->has_jsrs()) {
453 m = rewrite_jsrs(m, THREAD);
454 // Restore bytecodes to their unrewritten state if there are exceptions
455 // relocating bytecodes. If some are relocated, that is ok because that
456 // doesn't affect constant pool to cpCache rewriting.
457 if (HAS_PENDING_EXCEPTION) {
458 restore_bytecodes();
459 return;
460 }
461 // Method might have gotten rewritten.
462 methods->at_put(i, m());
463 }
464 }
465 }