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 jdk.internal.ref.CleanerFactory;
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 // CallSite instance is tracked by a Cleanable which clears native
72 // structures allocated for CallSite context. Though the CallSite can
73 // become unreachable, its Context is retained by the Cleanable instance
74 // (which is referenced from Cleaner instance which is referenced from
75 // CleanerFactory class) until cleanup is performed.
76 CleanerFactory.cleaner().register(cs, newContext);
77 return newContext;
78 }
79
80 @Override
81 public void run() {
82 MethodHandleNatives.clearCallSiteContext(this);
83 }
84 }
85
86 /** Invalidate all recorded nmethods. */
87 private static native void clearCallSiteContext(CallSiteContext context);
88
89 private static native void registerNatives();
90 static {
91 registerNatives();
92 }
93
94 /**
95 * Compile-time constants go here. This collection exists not only for
96 * reference from clients, but also for ensuring the VM and JDK agree on the
97 * values of these constants (see {@link #verifyConstants()}).
98 */
99 static class Constants {
100 Constants() { } // static only
101
102 static final int
103 MN_IS_METHOD = 0x00010000, // method (not constructor)
104 MN_IS_CONSTRUCTOR = 0x00020000, // constructor
105 MN_IS_FIELD = 0x00040000, // field
106 MN_IS_TYPE = 0x00080000, // nested type
107 MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected
108 MN_REFERENCE_KIND_SHIFT = 24, // refKind
109 MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT,
110 // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers:
111 MN_SEARCH_SUPERCLASSES = 0x00100000,
112 MN_SEARCH_INTERFACES = 0x00200000;
113
114 /**
115 * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
116 */
117 static final byte
118 REF_NONE = 0, // null value
119 REF_getField = 1,
120 REF_getStatic = 2,
121 REF_putField = 3,
122 REF_putStatic = 4,
123 REF_invokeVirtual = 5,
124 REF_invokeStatic = 6,
125 REF_invokeSpecial = 7,
126 REF_newInvokeSpecial = 8,
127 REF_invokeInterface = 9,
128 REF_LIMIT = 10;
129 }
130
131 static boolean refKindIsValid(int refKind) {
132 return (refKind > REF_NONE && refKind < REF_LIMIT);
133 }
134 static boolean refKindIsField(byte refKind) {
135 assert(refKindIsValid(refKind));
136 return (refKind <= REF_putStatic);
137 }
138 static boolean refKindIsGetter(byte refKind) {
139 assert(refKindIsValid(refKind));
140 return (refKind <= REF_getStatic);
141 }
142 static boolean refKindIsSetter(byte refKind) {
143 return refKindIsField(refKind) && !refKindIsGetter(refKind);
144 }
145 static boolean refKindIsMethod(byte refKind) {
146 return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
147 }
148 static boolean refKindIsConstructor(byte refKind) {
149 return (refKind == REF_newInvokeSpecial);
150 }
151 static boolean refKindHasReceiver(byte refKind) {
152 assert(refKindIsValid(refKind));
153 return (refKind & 1) != 0;
154 }
155 static boolean refKindIsStatic(byte refKind) {
156 return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
157 }
158 static boolean refKindDoesDispatch(byte refKind) {
159 assert(refKindIsValid(refKind));
160 return (refKind == REF_invokeVirtual ||
161 refKind == REF_invokeInterface);
162 }
163 static {
164 final int HR_MASK = ((1 << REF_getField) |
165 (1 << REF_putField) |
166 (1 << REF_invokeVirtual) |
167 (1 << REF_invokeSpecial) |
168 (1 << REF_invokeInterface)
169 );
170 for (byte refKind = REF_NONE+1; refKind < REF_LIMIT; refKind++) {
171 assert(refKindHasReceiver(refKind) == (((1<<refKind) & HR_MASK) != 0)) : refKind;
172 }
173 }
174 static String refKindName(byte refKind) {
175 assert(refKindIsValid(refKind));
176 switch (refKind) {
177 case REF_getField: return "getField";
178 case REF_getStatic: return "getStatic";
179 case REF_putField: return "putField";
180 case REF_putStatic: return "putStatic";
181 case REF_invokeVirtual: return "invokeVirtual";
182 case REF_invokeStatic: return "invokeStatic";
183 case REF_invokeSpecial: return "invokeSpecial";
184 case REF_newInvokeSpecial: return "newInvokeSpecial";
185 case REF_invokeInterface: return "invokeInterface";
186 default: return "REF_???";
187 }
188 }
189
190 private static native int getNamedCon(int which, Object[] name);
191 static boolean verifyConstants() {
192 Object[] box = { null };
193 for (int i = 0; ; i++) {
194 box[0] = null;
195 int vmval = getNamedCon(i, box);
196 if (box[0] == null) break;
197 String name = (String) box[0];
198 try {
199 Field con = Constants.class.getDeclaredField(name);
200 int jval = con.getInt(null);
201 if (jval == vmval) continue;
202 String err = (name+": JVM has "+vmval+" while Java has "+jval);
203 if (name.equals("CONV_OP_LIMIT")) {
204 System.err.println("warning: "+err);
205 continue;
206 }
207 throw new InternalError(err);
208 } catch (NoSuchFieldException | IllegalAccessException ex) {
209 String err = (name+": JVM has "+vmval+" which Java does not define");
210 // ignore exotic ops the JVM cares about; we just wont issue them
211 //System.err.println("warning: "+err);
212 continue;
213 }
214 }
215 return true;
216 }
217 static {
218 assert(verifyConstants());
219 }
220
221 // Up-calls from the JVM.
222 // These must NOT be public.
223
224 /**
225 * The JVM is linking an invokedynamic instruction. Create a reified call site for it.
226 */
227 static MemberName linkCallSite(Object callerObj,
228 Object bootstrapMethodObj,
229 Object nameObj, Object typeObj,
230 Object staticArguments,
231 Object[] appendixResult) {
232 MethodHandle bootstrapMethod = (MethodHandle)bootstrapMethodObj;
233 Class<?> caller = (Class<?>)callerObj;
234 String name = nameObj.toString().intern();
235 MethodType type = (MethodType)typeObj;
236 if (!TRACE_METHOD_LINKAGE)
237 return linkCallSiteImpl(caller, bootstrapMethod, name, type,
238 staticArguments, appendixResult);
239 return linkCallSiteTracing(caller, bootstrapMethod, name, type,
240 staticArguments, appendixResult);
241 }
242 static MemberName linkCallSiteImpl(Class<?> caller,
243 MethodHandle bootstrapMethod,
244 String name, MethodType type,
245 Object staticArguments,
246 Object[] appendixResult) {
247 CallSite callSite = CallSite.makeSite(bootstrapMethod,
248 name,
249 type,
250 staticArguments,
251 caller);
252 if (callSite instanceof ConstantCallSite) {
253 appendixResult[0] = callSite.dynamicInvoker();
254 return Invokers.linkToTargetMethod(type);
255 } else {
256 appendixResult[0] = callSite;
257 return Invokers.linkToCallSiteMethod(type);
258 }
259 }
260 // Tracing logic:
261 static MemberName linkCallSiteTracing(Class<?> caller,
262 MethodHandle bootstrapMethod,
263 String name, MethodType type,
264 Object staticArguments,
265 Object[] appendixResult) {
266 Object bsmReference = bootstrapMethod.internalMemberName();
267 if (bsmReference == null) bsmReference = bootstrapMethod;
268 Object staticArglist = (staticArguments instanceof Object[] ?
269 java.util.Arrays.asList((Object[]) staticArguments) :
270 staticArguments);
271 System.out.println("linkCallSite "+caller.getName()+" "+
272 bsmReference+" "+
273 name+type+"/"+staticArglist);
274 try {
275 MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
276 staticArguments, appendixResult);
277 System.out.println("linkCallSite => "+res+" + "+appendixResult[0]);
278 return res;
279 } catch (Throwable ex) {
280 System.out.println("linkCallSite => throw "+ex);
281 throw ex;
282 }
283 }
284
285 /**
286 * The JVM wants a pointer to a MethodType. Oblige it by finding or creating one.
287 */
288 static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
289 return MethodType.makeImpl(rtype, ptypes, true);
290 }
291
292 /**
293 * The JVM wants to link a call site that requires a dynamic type check.
294 * Name is a type-checking invoker, invokeExact or invoke.
295 * Return a JVM method (MemberName) to handle the invoking.
296 * The method assumes the following arguments on the stack:
297 * 0: the method handle being invoked
298 * 1-N: the arguments to the method handle invocation
299 * N+1: an optional, implicitly added argument (typically the given MethodType)
300 * <p>
301 * The nominal method at such a call site is an instance of
302 * a signature-polymorphic method (see @PolymorphicSignature).
303 * Such method instances are user-visible entities which are
304 * "split" from the generic placeholder method in {@code MethodHandle}.
305 * (Note that the placeholder method is not identical with any of
306 * its instances. If invoked reflectively, is guaranteed to throw an
307 * {@code UnsupportedOperationException}.)
308 * If the signature-polymorphic method instance is ever reified,
309 * it appears as a "copy" of the original placeholder
310 * (a native final member of {@code MethodHandle}) except
311 * that its type descriptor has shape required by the instance,
312 * and the method instance is <em>not</em> varargs.
313 * The method instance is also marked synthetic, since the
314 * method (by definition) does not appear in Java source code.
315 * <p>
316 * The JVM is allowed to reify this method as instance metadata.
317 * For example, {@code invokeBasic} is always reified.
318 * But the JVM may instead call {@code linkMethod}.
319 * If the result is an * ordered pair of a {@code (method, appendix)},
320 * the method gets all the arguments (0..N inclusive)
321 * plus the appendix (N+1), and uses the appendix to complete the call.
322 * In this way, one reusable method (called a "linker method")
323 * can perform the function of any number of polymorphic instance
324 * methods.
325 * <p>
326 * Linker methods are allowed to be weakly typed, with any or
327 * all references rewritten to {@code Object} and any primitives
328 * (except {@code long}/{@code float}/{@code double})
329 * rewritten to {@code int}.
330 * A linker method is trusted to return a strongly typed result,
331 * according to the specific method type descriptor of the
332 * signature-polymorphic instance it is emulating.
333 * This can involve (as necessary) a dynamic check using
334 * data extracted from the appendix argument.
335 * <p>
336 * The JVM does not inspect the appendix, other than to pass
337 * it verbatim to the linker method at every call.
338 * This means that the JDK runtime has wide latitude
339 * for choosing the shape of each linker method and its
340 * corresponding appendix.
341 * Linker methods should be generated from {@code LambdaForm}s
342 * so that they do not become visible on stack traces.
343 * <p>
344 * The {@code linkMethod} call is free to omit the appendix
345 * (returning null) and instead emulate the required function
346 * completely in the linker method.
347 * As a corner case, if N==255, no appendix is possible.
348 * In this case, the method returned must be custom-generated to
349 * to perform any needed type checking.
350 * <p>
351 * If the JVM does not reify a method at a call site, but instead
352 * calls {@code linkMethod}, the corresponding call represented
353 * in the bytecodes may mention a valid method which is not
354 * representable with a {@code MemberName}.
355 * Therefore, use cases for {@code linkMethod} tend to correspond to
356 * special cases in reflective code such as {@code findVirtual}
357 * or {@code revealDirect}.
358 */
359 static MemberName linkMethod(Class<?> callerClass, int refKind,
360 Class<?> defc, String name, Object type,
361 Object[] appendixResult) {
362 if (!TRACE_METHOD_LINKAGE)
363 return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
364 return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
365 }
366 static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
367 Class<?> defc, String name, Object type,
368 Object[] appendixResult) {
369 try {
370 if (defc == MethodHandle.class && refKind == REF_invokeVirtual) {
371 return Invokers.methodHandleInvokeLinkerMethod(name, fixMethodType(callerClass, type), appendixResult);
372 }
373 } catch (Throwable ex) {
374 if (ex instanceof LinkageError)
375 throw (LinkageError) ex;
376 else
377 throw new LinkageError(ex.getMessage(), ex);
378 }
379 throw new LinkageError("no such method "+defc.getName()+"."+name+type);
380 }
381 private static MethodType fixMethodType(Class<?> callerClass, Object type) {
382 if (type instanceof MethodType)
383 return (MethodType) type;
384 else
385 return MethodType.fromDescriptor((String)type, callerClass.getClassLoader());
386 }
387 // Tracing logic:
388 static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
389 Class<?> defc, String name, Object type,
390 Object[] appendixResult) {
391 System.out.println("linkMethod "+defc.getName()+"."+
392 name+type+"/"+Integer.toHexString(refKind));
393 try {
394 MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
395 System.out.println("linkMethod => "+res+" + "+appendixResult[0]);
396 return res;
397 } catch (Throwable ex) {
398 System.out.println("linkMethod => throw "+ex);
399 throw ex;
400 }
401 }
402
403
404 /**
405 * The JVM is resolving a CONSTANT_MethodHandle CP entry. And it wants our help.
406 * It will make an up-call to this method. (Do not change the name or signature.)
407 * The type argument is a Class for field requests and a MethodType for non-fields.
408 * <p>
409 * Recent versions of the JVM may also pass a resolved MemberName for the type.
410 * In that case, the name is ignored and may be null.
411 */
412 static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
413 Class<?> defc, String name, Object type) {
414 try {
415 Lookup lookup = IMPL_LOOKUP.in(callerClass);
416 assert(refKindIsValid(refKind));
417 return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
418 } catch (IllegalAccessException ex) {
419 Throwable cause = ex.getCause();
420 if (cause instanceof AbstractMethodError) {
421 throw (AbstractMethodError) cause;
422 } else {
423 Error err = new IllegalAccessError(ex.getMessage());
424 throw initCauseFrom(err, ex);
425 }
426 } catch (NoSuchMethodException ex) {
427 Error err = new NoSuchMethodError(ex.getMessage());
428 throw initCauseFrom(err, ex);
429 } catch (NoSuchFieldException ex) {
430 Error err = new NoSuchFieldError(ex.getMessage());
431 throw initCauseFrom(err, ex);
432 } catch (ReflectiveOperationException ex) {
433 Error err = new IncompatibleClassChangeError();
434 throw initCauseFrom(err, ex);
435 }
436 }
437
438 /**
439 * Use best possible cause for err.initCause(), substituting the
440 * cause for err itself if the cause has the same (or better) type.
441 */
442 private static Error initCauseFrom(Error err, Exception ex) {
443 Throwable th = ex.getCause();
444 if (err.getClass().isInstance(th))
445 return (Error) th;
446 err.initCause(th == null ? ex : th);
447 return err;
448 }
449
450 /**
451 * Is this method a caller-sensitive method?
452 * I.e., does it call Reflection.getCallerClass or a similar method
453 * to ask about the identity of its caller?
454 */
455 static boolean isCallerSensitive(MemberName mem) {
456 if (!mem.isInvocable()) return false; // fields are not caller sensitive
457
458 return mem.isCallerSensitive() || canBeCalledVirtual(mem);
459 }
460
461 static boolean canBeCalledVirtual(MemberName mem) {
462 assert(mem.isInvocable());
463 Class<?> defc = mem.getDeclaringClass();
464 switch (mem.getName()) {
465 case "checkMemberAccess":
466 return canBeCalledVirtual(mem, java.lang.SecurityManager.class);
467 case "getContextClassLoader":
468 return canBeCalledVirtual(mem, java.lang.Thread.class);
469 }
470 return false;
471 }
472
473 static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
474 Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
475 if (symbolicRefClass == definingClass) return true;
476 if (symbolicRef.isStatic() || symbolicRef.isPrivate()) return false;
477 return (definingClass.isAssignableFrom(symbolicRefClass) || // Msym overrides Mdef
478 symbolicRefClass.isInterface()); // Mdef implements Msym
479 }
480 }