1 /* 2 * Copyright (c) 2008, 2015, 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. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang.invoke; 27 28 import java.lang.invoke.MethodHandles.Lookup; 29 import java.lang.reflect.Field; 30 import static java.lang.invoke.MethodHandleNatives.Constants.*; 31 import static java.lang.invoke.MethodHandleStatics.*; 32 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP; 33 import sun.misc.Cleaner; 34 35 /** 36 * The JVM interface for the method handles package is all here. 37 * This is an interface internal and private to an implementation of JSR 292. 38 * <em>This class is not part of the JSR 292 standard.</em> 39 * @author jrose 40 */ 41 class MethodHandleNatives { 42 43 private MethodHandleNatives() { } // static only 44 45 /// MemberName support 46 47 static native void init(MemberName self, Object ref); 48 static native void expand(MemberName self); 49 static native MemberName resolve(MemberName self, Class<?> caller) throws LinkageError; 50 static native int getMembers(Class<?> defc, String matchName, String matchSig, 51 int matchFlags, Class<?> caller, int skip, MemberName[] results); 52 53 /// Field layout queries parallel to jdk.internal.misc.Unsafe: 54 static native long objectFieldOffset(MemberName self); // e.g., returns vmindex 55 static native long staticFieldOffset(MemberName self); // e.g., returns vmindex 56 static native Object staticFieldBase(MemberName self); // e.g., returns clazz 57 static native Object getMemberVMInfo(MemberName self); // returns {vmindex,vmtarget} 58 59 /// CallSite support 60 61 /** Tell the JVM that we need to change the target of a CallSite. */ 62 static native void setCallSiteTargetNormal(CallSite site, MethodHandle target); 63 static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target); 64 65 /** Represents a context to track nmethod dependencies on CallSite instance target. */ 66 static class CallSiteContext implements Runnable { 67 //@Injected JVM_nmethodBucket* vmdependencies; 68 69 static CallSiteContext make(CallSite cs) { 70 final CallSiteContext newContext = new CallSiteContext(); 71 // Cleaner is attached to CallSite instance and it clears native structures allocated for CallSite context. 72 // Though the CallSite can become unreachable, its Context is retained by the Cleaner instance (which is 73 // referenced from Cleaner class) until cleanup is performed. 74 Cleaner.create(cs, newContext); 75 return newContext; 76 } 77 78 @Override 79 public void run() { 80 MethodHandleNatives.clearCallSiteContext(this); 81 } 82 } 83 84 /** Invalidate all recorded nmethods. */ 85 private static native void clearCallSiteContext(CallSiteContext context); 86 87 private static native void registerNatives(); 88 static { 89 registerNatives(); 90 } 91 92 /** 93 * Compile-time constants go here. This collection exists not only for 94 * reference from clients, but also for ensuring the VM and JDK agree on the 95 * values of these constants (see {@link #verifyConstants()}). 96 */ 97 static class Constants { 98 Constants() { } // static only 99 100 static final int 101 MN_IS_METHOD = 0x00010000, // method (not constructor) 102 MN_IS_CONSTRUCTOR = 0x00020000, // constructor 103 MN_IS_FIELD = 0x00040000, // field 104 MN_IS_TYPE = 0x00080000, // nested type 105 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected 106 MN_REFERENCE_KIND_SHIFT = 24, // refKind 107 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT, 108 // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers: 109 MN_SEARCH_SUPERCLASSES = 0x00100000, 110 MN_SEARCH_INTERFACES = 0x00200000; 111 112 /** 113 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries. 114 */ 115 static final byte 116 REF_NONE = 0, // null value 117 REF_getField = 1, 118 REF_getStatic = 2, 119 REF_putField = 3, 120 REF_putStatic = 4, 121 REF_invokeVirtual = 5, 122 REF_invokeStatic = 6, 123 REF_invokeSpecial = 7, 124 REF_newInvokeSpecial = 8, 125 REF_invokeInterface = 9, 126 REF_LIMIT = 10; 127 } 128 129 static boolean refKindIsValid(int refKind) { 130 return (refKind > REF_NONE && refKind < REF_LIMIT); 131 } 132 static boolean refKindIsField(byte refKind) { 133 assert(refKindIsValid(refKind)); 134 return (refKind <= REF_putStatic); 135 } 136 static boolean refKindIsGetter(byte refKind) { 137 assert(refKindIsValid(refKind)); 138 return (refKind <= REF_getStatic); 139 } 140 static boolean refKindIsSetter(byte refKind) { 141 return refKindIsField(refKind) && !refKindIsGetter(refKind); 142 } 143 static boolean refKindIsMethod(byte refKind) { 144 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial); 145 } 146 static boolean refKindIsConstructor(byte refKind) { 147 return (refKind == REF_newInvokeSpecial); 148 } 149 static boolean refKindHasReceiver(byte refKind) { 150 assert(refKindIsValid(refKind)); 151 return (refKind & 1) != 0; 152 } 153 static boolean refKindIsStatic(byte refKind) { 154 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial); 155 } 156 static boolean refKindDoesDispatch(byte refKind) { 157 assert(refKindIsValid(refKind)); 158 return (refKind == REF_invokeVirtual || 159 refKind == REF_invokeInterface); 160 } 161 static { 162 final int HR_MASK = ((1 << REF_getField) | 163 (1 << REF_putField) | 164 (1 << REF_invokeVirtual) | 165 (1 << REF_invokeSpecial) | 166 (1 << REF_invokeInterface) 167 ); 168 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) { 169 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind; 170 } 171 } 172 static String refKindName(byte refKind) { 173 assert(refKindIsValid(refKind)); 174 switch (refKind) { 175 case REF_getField: return "getField"; 176 case REF_getStatic: return "getStatic"; 177 case REF_putField: return "putField"; 178 case REF_putStatic: return "putStatic"; 179 case REF_invokeVirtual: return "invokeVirtual"; 180 case REF_invokeStatic: return "invokeStatic"; 181 case REF_invokeSpecial: return "invokeSpecial"; 182 case REF_newInvokeSpecial: return "newInvokeSpecial"; 183 case REF_invokeInterface: return "invokeInterface"; 184 default: return "REF_???"; 185 } 186 } 187 188 private static native int getNamedCon(int which, Object[] name); 189 static boolean verifyConstants() { 190 Object[] box = { null }; 191 for (int i = 0; ; i++) { 192 box[0] = null; 193 int vmval = getNamedCon(i, box); 194 if (box[0] == null) break; 195 String name = (String) box[0]; 196 try { 197 Field con = Constants.class.getDeclaredField(name); 198 int jval = con.getInt(null); 199 if (jval == vmval) continue; 200 String err = (name+": JVM has "+vmval+" while Java has "+jval); 201 if (name.equals("CONV_OP_LIMIT")) { 202 System.err.println("warning: "+err); 203 continue; 204 } 205 throw new InternalError(err); 206 } catch (NoSuchFieldException | IllegalAccessException ex) { 207 String err = (name+": JVM has "+vmval+" which Java does not define"); 208 // ignore exotic ops the JVM cares about; we just wont issue them 209 //System.err.println("warning: "+err); 210 continue; 211 } 212 } 213 return true; 214 } 215 static { 216 assert(verifyConstants()); 217 } 218 219 // Up-calls from the JVM. 220 // These must NOT be public. 221 222 /** 223 * The JVM is linking an invokedynamic instruction. Create a reified call site for it. 224 */ 225 static MemberName linkCallSite(Object callerObj, 226 Object bootstrapMethodObj, 227 Object nameObj, Object typeObj, 228 Object staticArguments, 229 Object[] appendixResult) { 230 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj; 231 Class<?> caller = (Class<?>)callerObj; 232 String name = nameObj.toString().intern(); 233 MethodType type = (MethodType)typeObj; 234 if (!TRACE_METHOD_LINKAGE) 235 return linkCallSiteImpl(caller, bootstrapMethod, name, type, 236 staticArguments, appendixResult); 237 return linkCallSiteTracing(caller, bootstrapMethod, name, type, 238 staticArguments, appendixResult); 239 } 240 static MemberName linkCallSiteImpl(Class<?> caller, 241 MethodHandle bootstrapMethod, 242 String name, MethodType type, 243 Object staticArguments, 244 Object[] appendixResult) { 245 CallSite callSite = CallSite.makeSite(bootstrapMethod, 246 name, 247 type, 248 staticArguments, 249 caller); 250 if (callSite instanceof ConstantCallSite) { 251 appendixResult[0] = callSite.dynamicInvoker(); 252 return Invokers.linkToTargetMethod(type); 253 } else { 254 appendixResult[0] = callSite; 255 return Invokers.linkToCallSiteMethod(type); 256 } 257 } 258 // Tracing logic: 259 static MemberName linkCallSiteTracing(Class<?> caller, 260 MethodHandle bootstrapMethod, 261 String name, MethodType type, 262 Object staticArguments, 263 Object[] appendixResult) { 264 Object bsmReference = bootstrapMethod.internalMemberName(); 265 if (bsmReference == null) bsmReference = bootstrapMethod; 266 Object staticArglist = (staticArguments instanceof Object[] ? 267 java.util.Arrays.asList((Object[]) staticArguments) : 268 staticArguments); 269 System.out.println("linkCallSite "+caller.getName()+" "+ 270 bsmReference+" "+ 271 name+type+"/"+staticArglist); 272 try { 273 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type, 274 staticArguments, appendixResult); 275 System.out.println("linkCallSite => "+res+" + "+appendixResult[0]); 276 return res; 277 } catch (Throwable ex) { 278 System.out.println("linkCallSite => throw "+ex); 279 throw ex; 280 } 281 } 282 283 /** 284 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one. 285 */ 286 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) { 287 return MethodType.makeImpl(rtype, ptypes, true); 288 } 289 290 /** 291 * The JVM wants to link a call site that requires a dynamic type check. 292 * Name is a type-checking invoker, invokeExact or invoke. 293 * Return a JVM method (MemberName) to handle the invoking. 294 * The method assumes the following arguments on the stack: 295 * 0: the method handle being invoked 296 * 1-N: the arguments to the method handle invocation 297 * N+1: an optional, implicitly added argument (typically the given MethodType) 298 * <p> 299 * The nominal method at such a call site is an instance of 300 * a signature-polymorphic method (see @PolymorphicSignature). 301 * Such method instances are user-visible entities which are 302 * "split" from the generic placeholder method in {@code MethodHandle}. 303 * (Note that the placeholder method is not identical with any of 304 * its instances. If invoked reflectively, is guaranteed to throw an 305 * {@code UnsupportedOperationException}.) 306 * If the signature-polymorphic method instance is ever reified, 307 * it appears as a "copy" of the original placeholder 308 * (a native final member of {@code MethodHandle}) except 309 * that its type descriptor has shape required by the instance, 310 * and the method instance is <em>not</em> varargs. 311 * The method instance is also marked synthetic, since the 312 * method (by definition) does not appear in Java source code. 313 * <p> 314 * The JVM is allowed to reify this method as instance metadata. 315 * For example, {@code invokeBasic} is always reified. 316 * But the JVM may instead call {@code linkMethod}. 317 * If the result is an * ordered pair of a {@code (method, appendix)}, 318 * the method gets all the arguments (0..N inclusive) 319 * plus the appendix (N+1), and uses the appendix to complete the call. 320 * In this way, one reusable method (called a "linker method") 321 * can perform the function of any number of polymorphic instance 322 * methods. 323 * <p> 324 * Linker methods are allowed to be weakly typed, with any or 325 * all references rewritten to {@code Object} and any primitives 326 * (except {@code long}/{@code float}/{@code double}) 327 * rewritten to {@code int}. 328 * A linker method is trusted to return a strongly typed result, 329 * according to the specific method type descriptor of the 330 * signature-polymorphic instance it is emulating. 331 * This can involve (as necessary) a dynamic check using 332 * data extracted from the appendix argument. 333 * <p> 334 * The JVM does not inspect the appendix, other than to pass 335 * it verbatim to the linker method at every call. 336 * This means that the JDK runtime has wide latitude 337 * for choosing the shape of each linker method and its 338 * corresponding appendix. 339 * Linker methods should be generated from {@code LambdaForm}s 340 * so that they do not become visible on stack traces. 341 * <p> 342 * The {@code linkMethod} call is free to omit the appendix 343 * (returning null) and instead emulate the required function 344 * completely in the linker method. 345 * As a corner case, if N==255, no appendix is possible. 346 * In this case, the method returned must be custom-generated to 347 * to perform any needed type checking. 348 * <p> 349 * If the JVM does not reify a method at a call site, but instead 350 * calls {@code linkMethod}, the corresponding call represented 351 * in the bytecodes may mention a valid method which is not 352 * representable with a {@code MemberName}. 353 * Therefore, use cases for {@code linkMethod} tend to correspond to 354 * special cases in reflective code such as {@code findVirtual} 355 * or {@code revealDirect}. 356 */ 357 static MemberName linkMethod(Class<?> callerClass, int refKind, 358 Class<?> defc, String name, Object type, 359 Object[] appendixResult) { 360 if (!TRACE_METHOD_LINKAGE) 361 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult); 362 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult); 363 } 364 static MemberName linkMethodImpl(Class<?> callerClass, int refKind, 365 Class<?> defc, String name, Object type, 366 Object[] appendixResult) { 367 try { 368 if (defc == MethodHandle.class && refKind == REF_invokeVirtual) { 369 return Invokers.methodHandleInvokeLinkerMethod(name, fixMethodType(callerClass, type), appendixResult); 370 } 371 } catch (Throwable ex) { 372 if (ex instanceof LinkageError) 373 throw (LinkageError) ex; 374 else 375 throw new LinkageError(ex.getMessage(), ex); 376 } 377 throw new LinkageError("no such method "+defc.getName()+"."+name+type); 378 } 379 private static MethodType fixMethodType(Class<?> callerClass, Object type) { 380 if (type instanceof MethodType) 381 return (MethodType) type; 382 else 383 return MethodType.fromDescriptor((String)type, callerClass.getClassLoader()); 384 } 385 // Tracing logic: 386 static MemberName linkMethodTracing(Class<?> callerClass, int refKind, 387 Class<?> defc, String name, Object type, 388 Object[] appendixResult) { 389 System.out.println("linkMethod "+defc.getName()+"."+ 390 name+type+"/"+Integer.toHexString(refKind)); 391 try { 392 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult); 393 System.out.println("linkMethod => "+res+" + "+appendixResult[0]); 394 return res; 395 } catch (Throwable ex) { 396 System.out.println("linkMethod => throw "+ex); 397 throw ex; 398 } 399 } 400 401 402 /** 403 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help. 404 * It will make an up-call to this method. (Do not change the name or signature.) 405 * The type argument is a Class for field requests and a MethodType for non-fields. 406 * <p> 407 * Recent versions of the JVM may also pass a resolved MemberName for the type. 408 * In that case, the name is ignored and may be null. 409 */ 410 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind, 411 Class<?> defc, String name, Object type) { 412 try { 413 Lookup lookup = IMPL_LOOKUP.in(callerClass); 414 assert(refKindIsValid(refKind)); 415 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type); 416 } catch (IllegalAccessException ex) { 417 Throwable cause = ex.getCause(); 418 if (cause instanceof AbstractMethodError) { 419 throw (AbstractMethodError) cause; 420 } else { 421 Error err = new IllegalAccessError(ex.getMessage()); 422 throw initCauseFrom(err, ex); 423 } 424 } catch (NoSuchMethodException ex) { 425 Error err = new NoSuchMethodError(ex.getMessage()); 426 throw initCauseFrom(err, ex); 427 } catch (NoSuchFieldException ex) { 428 Error err = new NoSuchFieldError(ex.getMessage()); 429 throw initCauseFrom(err, ex); 430 } catch (ReflectiveOperationException ex) { 431 Error err = new IncompatibleClassChangeError(); 432 throw initCauseFrom(err, ex); 433 } 434 } 435 436 /** 437 * Use best possible cause for err.initCause(), substituting the 438 * cause for err itself if the cause has the same (or better) type. 439 */ 440 private static Error initCauseFrom(Error err, Exception ex) { 441 Throwable th = ex.getCause(); 442 if (err.getClass().isInstance(th)) 443 return (Error) th; 444 err.initCause(th == null ? ex : th); 445 return err; 446 } 447 448 /** 449 * Is this method a caller-sensitive method? 450 * I.e., does it call Reflection.getCallerClass or a similar method 451 * to ask about the identity of its caller? 452 */ 453 static boolean isCallerSensitive(MemberName mem) { 454 if (!mem.isInvocable()) return false; // fields are not caller sensitive 455 456 return mem.isCallerSensitive() || canBeCalledVirtual(mem); 457 } 458 459 static boolean canBeCalledVirtual(MemberName mem) { 460 assert(mem.isInvocable()); 461 Class<?> defc = mem.getDeclaringClass(); 462 switch (mem.getName()) { 463 case "checkMemberAccess": 464 return canBeCalledVirtual(mem, java.lang.SecurityManager.class); 465 case "getContextClassLoader": 466 return canBeCalledVirtual(mem, java.lang.Thread.class); 467 } 468 return false; 469 } 470 471 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) { 472 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass(); 473 if (symbolicRefClass == definingClass) return true; 474 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false; 475 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef 476 symbolicRefClass.isInterface()); // Mdef implements Msym 477 } 478 }