/*
* 在'clazz'中，我们有一个方法指向另一个方法，但它可能指向派生类中的一个方法，我们想要从虚拟函数表中找到实际入口,如果'class'是一个接口，我们不得不在短时间内做更多的挖掘
*
* 对于'direct'方法(private / constructor).我们仅仅返回原生态方法
*
* (这里被适用于反射和JNI调用)
*/
const Method* dvmGetVirtualizedMethod(const ClassObject* clazz,
const Method* meth)
{
Method* actualMeth;
int methodIndex;
if (dvmIsDirectMethod(meth)) {
/* no vtable entry for these */
assert(!dvmIsStaticMethod(meth));
return meth;
}
/*
* If the method was declared in an interface, we need to scan through
* the class' list of interfaces for it, and find the vtable index
* from that.
*
* TODO: use the interface cache.
*/
if (dvmIsInterfaceClass(meth->clazz)) {
int i;
for (i = 0; i < clazz->iftableCount; i++) {
if (clazz->iftable[i].clazz == meth->clazz)
break;
}
if (i == clazz->iftableCount) {
dvmThrowIncompatibleClassChangeError(
"invoking method from interface not implemented by class");
return NULL;
}
methodIndex = clazz->iftable[i].methodIndexArray[meth->methodIndex];
} else {
methodIndex = meth->methodIndex;
}
assert(methodIndex >= 0 && methodIndex < clazz->vtableCount);
actualMeth = clazz->vtable[methodIndex];
/*
* Make sure there's code to execute.
*/
if (dvmIsAbstractMethod(actualMeth)) {
dvmThrowAbstractMethodError(NULL);
return NULL;
}
assert(!dvmIsMirandaMethod(actualMeth));
return actualMeth;
}
/*
* Determine the source file line number based on the program counter.
* "pc" is an offset, in 16-bit units, from the start of the method's code.
*
* Returns -1 if no match was found (possibly because the source files were
* compiled without "-g", so no line number information is present).
* Returns -2 for native methods (as expected in exception traces).
*/
int dvmLineNumFromPC(const Method* method, u4 relPc)
{
const DexCode* pDexCode = dvmGetMethodCode(method);
if (pDexCode == NULL) {
if (dvmIsNativeMethod(method) && !dvmIsAbstractMethod(method))
return -2;
return -1; /* can happen for abstract method stub */
}
LineNumFromPcContext context;
memset(&context, 0, sizeof(context));
context.address = relPc;
// A method with no line number info should return -1
context.lineNum = -1;
dexDecodeDebugInfo(method->clazz->pDvmDex->pDexFile, pDexCode,
method->clazz->descriptor,
method->prototype.protoIdx,
method->accessFlags,
lineNumForPcCb, NULL, &context);
return context.lineNum;
}
/*
* We're calling an interpreted method from an internal VM function or
* via reflection.
*
* Push a frame for an interpreted method onto the stack. This is only
* used when calling into interpreted code from native code. (The
* interpreter does its own stack frame manipulation for interp-->interp
* calls.)
*
* The size we need to reserve is the sum of parameters, local variables,
* saved goodies, and outbound parameters.
*
* We start by inserting a "break" frame, which ensures that the interpreter
* hands control back to us after the function we call returns or an
* uncaught exception is thrown.
*/
static bool dvmPushInterpFrame(Thread* self, const Method* method)
{
StackSaveArea* saveBlock;
StackSaveArea* breakSaveBlock;
int stackReq;
u1* stackPtr;
assert(!dvmIsNativeMethod(method));
assert(!dvmIsAbstractMethod(method));
stackReq = method->registersSize * 4 // params + locals
+ sizeof(StackSaveArea) * 2 // break frame + regular frame
+ method->outsSize * 4; // args to other methods
if (self->interpSave.curFrame != NULL)
stackPtr = (u1*) SAVEAREA_FROM_FP(self->interpSave.curFrame);
else
stackPtr = self->interpStackStart;
if (stackPtr - stackReq < self->interpStackEnd) {
/* not enough space */
ALOGW("Stack overflow on call to interp "
"(req=%d top=%p cur=%p size=%d %s.%s)",
stackReq, self->interpStackStart, self->interpSave.curFrame,
self->interpStackSize, method->clazz->descriptor, method->name);
dvmHandleStackOverflow(self, method);
assert(dvmCheckException(self));
return false;
}
/*
* Shift the stack pointer down, leaving space for the function's
* args/registers and save area.
*/
stackPtr -= sizeof(StackSaveArea);
breakSaveBlock = (StackSaveArea*)stackPtr;
stackPtr -= method->registersSize * 4 + sizeof(StackSaveArea);
saveBlock = (StackSaveArea*) stackPtr;
#if !defined(NDEBUG) && !defined(PAD_SAVE_AREA)
/* debug -- memset the new stack, unless we want valgrind's help */
memset(stackPtr - (method->outsSize*4), 0xaf, stackReq);
#endif
#ifdef EASY_GDB
breakSaveBlock->prevSave =
(StackSaveArea*)FP_FROM_SAVEAREA(self->interpSave.curFrame);
saveBlock->prevSave = breakSaveBlock;
#endif
breakSaveBlock->prevFrame = self->interpSave.curFrame;
breakSaveBlock->savedPc = NULL; // not required
breakSaveBlock->xtra.localRefCookie = 0; // not required
breakSaveBlock->method = NULL;
saveBlock->prevFrame = FP_FROM_SAVEAREA(breakSaveBlock);
saveBlock->savedPc = NULL; // not required
saveBlock->xtra.currentPc = NULL; // not required?
saveBlock->method = method;
LOGVV("PUSH frame: old=%p new=%p (size=%d)",
self->interpSave.curFrame, FP_FROM_SAVEAREA(saveBlock),
(u1*)self->interpSave.curFrame - (u1*)FP_FROM_SAVEAREA(saveBlock));
self->interpSave.curFrame = FP_FROM_SAVEAREA(saveBlock);
return true;
}
GOTO_TARGET_END
GOTO_TARGET(invokeSuper, bool methodCallRange)
{
Method* baseMethod;
u2 thisReg;
EXPORT_PC();
vsrc1 = INST_AA(inst); /* AA (count) or BA (count + arg 5) */
ref = FETCH(1); /* method ref */
vdst = FETCH(2); /* 4 regs -or- first reg */
if (methodCallRange) {
ILOGV("|invoke-super-range args=%d @0x%04x {regs=v%d-v%d}",
vsrc1, ref, vdst, vdst+vsrc1-1);
thisReg = vdst;
} else {
ILOGV("|invoke-super args=%d @0x%04x {regs=0x%04x %x}",
vsrc1 >> 4, ref, vdst, vsrc1 & 0x0f);
thisReg = vdst & 0x0f;
}
/* impossible in well-formed code, but we must check nevertheless */
if (!checkForNull((Object*) GET_REGISTER(thisReg)))
GOTO_exceptionThrown();
/*
* Resolve the method. This is the correct method for the static
* type of the object. We also verify access permissions here.
* The first arg to dvmResolveMethod() is just the referring class
* (used for class loaders and such), so we don't want to pass
* the superclass into the resolution call.
*/
baseMethod = dvmDexGetResolvedMethod(methodClassDex, ref);
if (baseMethod == NULL) {
baseMethod = dvmResolveMethod(curMethod->clazz, ref,METHOD_VIRTUAL);
if (baseMethod == NULL) {
ILOGV("+ unknown method or access denied\n");
GOTO_exceptionThrown();
}
}
/*
* Combine the object we found with the vtable offset in the
* method's class.
*
* We're using the current method's class' superclass, not the
* superclass of "this". This is because we might be executing
* in a method inherited from a superclass, and we want to run
* in that class' superclass.
*/
if (baseMethod->methodIndex >= curMethod->clazz->super->vtableCount) {
/*
* Method does not exist in the superclass. Could happen if
* superclass gets updated.
*/
dvmThrowException("Ljava/lang/NoSuchMethodError;",
baseMethod->name);
GOTO_exceptionThrown();
}
methodToCall = curMethod->clazz->super->vtable[baseMethod->methodIndex];
#if 0
if (dvmIsAbstractMethod(methodToCall)) {
dvmThrowException("Ljava/lang/AbstractMethodError;",
"abstract method not implemented");
GOTO_exceptionThrown();
}
#else
assert(!dvmIsAbstractMethod(methodToCall) ||
methodToCall->nativeFunc != NULL);
#endif
LOGVV("+++ base=%s.%s super-virtual=%s.%s\n",
baseMethod->clazz->descriptor, baseMethod->name,
methodToCall->clazz->descriptor, methodToCall->name);
assert(methodToCall != NULL);
GOTO_invokeMethod(methodCallRange, methodToCall, vsrc1, vdst);
}
/*
Perform verification on a single method.
执行单个方法的校验
We do this in three passes:
(1) Walk through all code units, determining instruction locations,
widths, and other characteristics.
(2) Walk through all code units, performing static checks on
operands.
(3) Iterate through the method, checking type safety and looking
for code flow problems.
校验分3次处理：
(1) 遍历所有代码单元，确定指令位置，宽度，和其它特征。
(2) 遍历所有代码单元，对操作码执行静态检查。
(3) 通过方法迭代，检查类型安全并且寻找代码流的问题。
Some checks may be bypassed depending on the verification mode. We can't
turn this stuff off completely if we want to do "exact" GC.
一些检查可以避免，这取决于校验模式。我们不能完全关闭这些校验，如果想做“精确”的垃圾回收。
TODO: cite source?
Confirmed here:
- code array must not be empty
- (N/A) code_length must be less than 65536
Confirmed by computeWidthsAndCountOps():
- opcode of first instruction begins at index 0
- only documented instructions may appear
- each instruction follows the last
- last byte of last instruction is at (code_length-1)
*/
static bool verifyMethod(Method* meth)
{
bool result = false;
/*
Verifier state blob. Various values will be cached here so we
can avoid expensive lookups and pass fewer arguments around.
数据校验器数据结构体。不同的值将被缓存到这里，因此我们可以通过极少的参数进行更有效查找。
可以缓存数据。数据结构参见于CodeVerify.h头文件。
*/
VerifierData vdata;
#if 1 // ndef NDEBUG
memset(&vdata, 0x99, sizeof(vdata));
#endif
// 校验器数据初始化
vdata.method = meth;
vdata.insnsSize = dvmGetMethodInsnsSize(meth);
vdata.insnRegCount = meth->registersSize;
vdata.insnFlags = NULL;
vdata.uninitMap = NULL;
vdata.basicBlocks = NULL;
/*
If there aren't any instructions, make sure that's expected, then
exit successfully. Note: for native methods, meth->insns gets set
to a native function pointer on first call, so don't use that as
an indicator.
如果没有任何指令，确保本地方法和抽象方法均可被访问，
然后成功退出。
*/
if (vdata.insnsSize == 0) {
if (!dvmIsNativeMethod(meth) && !dvmIsAbstractMethod(meth)) {
LOG_VFY_METH(meth,
"VFY: zero-length code in concrete non-native method");
goto bail;
}
goto success;
}
/*
Sanity-check the register counts. ins + locals = registers, so make
sure that ins <= registers.
校验寄存器个数。 指令寄存器ins + 本地寄存器locals = All，因此确保指令寄存器<= All。
*/
if (meth->insSize > meth->registersSize) {
LOG_VFY_METH(meth, "VFY: bad register counts (ins=%d regs=%d)",
meth->insSize, meth->registersSize);
goto bail;
}
/*
Allocate and populate an array to hold instruction data.
TODO: Consider keeping a reusable pre-allocated array sitting
around for smaller methods.
给指令分配空间
*/
vdata.insnFlags = (InsnFlags*) calloc(vdata.insnsSize, sizeof(InsnFlags));
if (vdata.insnFlags == NULL)
goto bail;
/*
Compute the width of each instruction and store the result in insnFlags.
Count up the #of occurrences of certain opcodes while we're at it.
计算每条指令宽度并且存储 insnFlags 中的结果。
*/
if (!computeWidthsAndCountOps(&vdata))
goto bail;
/*
Allocate a map to hold the classes of uninitialized instances.
分配一个map来持有未初始化的实例的类(s)
*/
vdata.uninitMap = dvmCreateUninitInstanceMap(meth, vdata.insnFlags,
vdata.newInstanceCount);
if (vdata.uninitMap == NULL)
goto bail;
/*
Set the "in try" flags for all instructions guarded by a "try" block.
Also sets the "branch target" flag on exception handlers.
对所有try块指令设置“in try”标识。
同时在异常句柄处设置“branch target”标识。
*/
if (!scanTryCatchBlocks(meth, vdata.insnFlags))
goto bail;
/*
Perform static instruction verification. Also sets the "branch
target" flags.
执行静态校验。同时设置“brach target”标识。
*/
if (!verifyInstructions(&vdata))
goto bail;
/*
Do code-flow analysis.
We could probably skip this for a method with no registers, but
that's so rare that there's little point in checking.
做代码流分析
也许可能会跳过一个没有寄存器的方法，但这种情况不见罕见，没有必要检查。
*/
if (!dvmVerifyCodeFlow(&vdata)) {
//ALOGD("+++ %s failed code flow", meth->name);
goto bail;
}
success:
result = true;
bail:
dvmFreeVfyBasicBlocks(&vdata);
dvmFreeUninitInstanceMap(vdata.uninitMap);
free(vdata.insnFlags);
return result;
}
GOTO_TARGET_END
GOTO_TARGET(invokeVirtual, bool methodCallRange)
{
Method* baseMethod;
Object* thisPtr;
EXPORT_PC();
vsrc1 = INST_AA(inst); /* AA (count) or BA (count + arg 5) */
ref = FETCH(1); /* method ref */
vdst = FETCH(2); /* 4 regs -or- first reg */
/*
* The object against which we are executing a method is always
* in the first argument.
*/
if (methodCallRange) {
assert(vsrc1 > 0);
ILOGV("|invoke-virtual-range args=%d @0x%04x {regs=v%d-v%d}",
vsrc1, ref, vdst, vdst+vsrc1-1);
thisPtr = (Object*) GET_REGISTER(vdst);
} else {
assert((vsrc1>>4) > 0);
ILOGV("|invoke-virtual args=%d @0x%04x {regs=0x%04x %x}",
vsrc1 >> 4, ref, vdst, vsrc1 & 0x0f);
thisPtr = (Object*) GET_REGISTER(vdst & 0x0f);
}
if (!checkForNull(thisPtr))
GOTO_exceptionThrown();
/*
* Resolve the method. This is the correct method for the static
* type of the object. We also verify access permissions here.
*/
baseMethod = dvmDexGetResolvedMethod(methodClassDex, ref);
if (baseMethod == NULL) {
baseMethod = dvmResolveMethod(curMethod->clazz, ref,METHOD_VIRTUAL);
if (baseMethod == NULL) {
ILOGV("+ unknown method or access denied\n");
GOTO_exceptionThrown();
}
}
/*
* Combine the object we found with the vtable offset in the
* method.
*/
assert(baseMethod->methodIndex < thisPtr->clazz->vtableCount);
methodToCall = thisPtr->clazz->vtable[baseMethod->methodIndex];
#if 0
if (dvmIsAbstractMethod(methodToCall)) {
/*
* This can happen if you create two classes, Base and Sub, where
* Sub is a sub-class of Base. Declare a protected abstract
* method foo() in Base, and invoke foo() from a method in Base.
* Base is an "abstract base class" and is never instantiated
* directly. Now, Override foo() in Sub, and use Sub. This
* Works fine unless Sub stops providing an implementation of
* the method.
*/
dvmThrowException("Ljava/lang/AbstractMethodError;",
"abstract method not implemented");
GOTO_exceptionThrown();
}
#else
assert(!dvmIsAbstractMethod(methodToCall) ||
methodToCall->nativeFunc != NULL);
#endif
LOGVV("+++ base=%s.%s virtual[%d]=%s.%s\n",
baseMethod->clazz->descriptor, baseMethod->name,
(u4) baseMethod->methodIndex,
methodToCall->clazz->descriptor, methodToCall->name);
assert(methodToCall != NULL);
#if 0
if (vsrc1 != methodToCall->insSize) {
LOGW("WRONG METHOD: base=%s.%s virtual[%d]=%s.%s\n",
baseMethod->clazz->descriptor, baseMethod->name,
(u4) baseMethod->methodIndex,
methodToCall->clazz->descriptor, methodToCall->name);
//dvmDumpClass(baseMethod->clazz);
//dvmDumpClass(methodToCall->clazz);
dvmDumpAllClasses(0);
}
#endif
GOTO_invokeMethod(methodCallRange, methodToCall, vsrc1, vdst);
}
/*
* Resolve an interface method reference.
*
* Returns NULL with an exception raised on failure.
*/
Method* dvmResolveInterfaceMethod(const ClassObject* referrer, u4 methodIdx)
{
DvmDex* pDvmDex = referrer->pDvmDex;
ClassObject* resClass;
const DexMethodId* pMethodId;
Method* resMethod;
int i;
LOGVV("--- resolving interface method %d (referrer=%s)\n",
methodIdx, referrer->descriptor);
pMethodId = dexGetMethodId(pDvmDex->pDexFile, methodIdx);
resClass = dvmResolveClass(referrer, pMethodId->classIdx, false);
if (resClass == NULL) {
/* can't find the class that the method is a part of */
assert(dvmCheckException(dvmThreadSelf()));
return NULL;
}
if (!dvmIsInterfaceClass(resClass)) {
/* whoops */
dvmThrowExceptionWithClassMessage(
"Ljava/lang/IncompatibleClassChangeError;",
resClass->descriptor);
return NULL;
}
/*
* This is the first time the method has been resolved. Set it in our
* resolved-method structure. It always resolves to the same thing,
* so looking it up and storing it doesn't create a race condition.
*
* If we scan into the interface's superclass -- which is always
* java/lang/Object -- we will catch things like:
* interface I ...
* I myobj = (something that implements I)
* myobj.hashCode()
* However, the Method->methodIndex will be an offset into clazz->vtable,
* rather than an offset into clazz->iftable. The invoke-interface
* code can test to see if the method returned is abstract or concrete,
* and use methodIndex accordingly. I'm not doing this yet because
* (a) we waste time in an unusual case, and (b) we're probably going
* to fix it in the DEX optimizer.
*
* We do need to scan the superinterfaces, in case we're invoking a
* superinterface method on an interface reference. The class in the
* DexTypeId is for the static type of the object, not the class in
* which the method is first defined. We have the full, flattened
* list in "iftable".
*/
const char* methodName =
dexStringById(pDvmDex->pDexFile, pMethodId->nameIdx);
DexProto proto;
dexProtoSetFromMethodId(&proto, pDvmDex->pDexFile, pMethodId);
LOGVV("+++ looking for '%s' '%s' in resClass='%s'\n",
methodName, methodSig, resClass->descriptor);
resMethod = dvmFindVirtualMethod(resClass, methodName, &proto);
if (resMethod == NULL) {
LOGVV("+++ did not resolve immediately\n");
for (i = 0; i < resClass->iftableCount; i++) {
resMethod = dvmFindVirtualMethod(resClass->iftable[i].clazz,
methodName, &proto);
if (resMethod != NULL)
break;
}
if (resMethod == NULL) {
dvmThrowException("Ljava/lang/NoSuchMethodError;", methodName);
return NULL;
}
} else {
LOGVV("+++ resolved immediately: %s (%s %d)\n", resMethod->name,
resMethod->clazz->descriptor, (u4) resMethod->methodIndex);
}
LOGVV("--- found interface method %d (%s.%s)\n",
methodIdx, resClass->descriptor, resMethod->name);
/* we're expecting this to be abstract */
assert(dvmIsAbstractMethod(resMethod));
/* interface methods are always public; no need to check access */
/*
* The interface class *may* be initialized. According to VM spec
* v2 2.17.4, the interfaces a class refers to "need not" be initialized
* when the class is initialized.
*
* It isn't necessary for an interface class to be initialized before
* we resolve methods on that interface.
*
* We choose not to do the initialization now.
*/
//assert(dvmIsClassInitialized(resMethod->clazz));
/*
* The class is initialized, the method has been found. Add a pointer
* to our data structure so we don't have to jump through the hoops again.
*/
dvmDexSetResolvedMethod(pDvmDex, methodIdx, resMethod);
return resMethod;
}
/*
* Find the method corresponding to "methodRef".
*
* We use "referrer" to find the DexFile with the constant pool that
* "methodRef" is an index into. We also use its class loader. The method
* being resolved may very well be in a different DEX file.
*
* If this is a static method, we ensure that the method's class is
* initialized.
*/
Method* dvmResolveMethod(const ClassObject* referrer, u4 methodIdx,
MethodType methodType)
{
DvmDex* pDvmDex = referrer->pDvmDex;
ClassObject* resClass;
const DexMethodId* pMethodId;
Method* resMethod;
assert(methodType != METHOD_INTERFACE);
LOGVV("--- resolving method %u (referrer=%s)\n", methodIdx,
referrer->descriptor);
pMethodId = dexGetMethodId(pDvmDex->pDexFile, methodIdx);
resClass = dvmResolveClass(referrer, pMethodId->classIdx, false);
if (resClass == NULL) {
/* can't find the class that the method is a part of */
assert(dvmCheckException(dvmThreadSelf()));
return NULL;
}
if (dvmIsInterfaceClass(resClass)) {
/* method is part of an interface */
dvmThrowExceptionWithClassMessage(
"Ljava/lang/IncompatibleClassChangeError;",
resClass->descriptor);
return NULL;
}
const char* name = dexStringById(pDvmDex->pDexFile, pMethodId->nameIdx);
DexProto proto;
dexProtoSetFromMethodId(&proto, pDvmDex->pDexFile, pMethodId);
/*
* We need to chase up the class hierarchy to find methods defined
* in super-classes. (We only want to check the current class
* if we're looking for a constructor; since DIRECT calls are only
* for constructors and private methods, we don't want to walk up.)
*/
if (methodType == METHOD_DIRECT) {
resMethod = dvmFindDirectMethod(resClass, name, &proto);
} else if (methodType == METHOD_STATIC) {
resMethod = dvmFindDirectMethodHier(resClass, name, &proto);
} else {
resMethod = dvmFindVirtualMethodHier(resClass, name, &proto);
}
if (resMethod == NULL) {
dvmThrowException("Ljava/lang/NoSuchMethodError;", name);
return NULL;
}
LOGVV("--- found method %d (%s.%s)\n",
methodIdx, resClass->descriptor, resMethod->name);
/* see if this is a pure-abstract method */
if (dvmIsAbstractMethod(resMethod) && !dvmIsAbstractClass(resClass)) {
dvmThrowException("Ljava/lang/AbstractMethodError;", name);
return NULL;
}
/*
* If we're the first to resolve this class, we need to initialize
* it now. Only necessary for METHOD_STATIC.
*/
if (methodType == METHOD_STATIC) {
if (!dvmIsClassInitialized(resMethod->clazz) &&
!dvmInitClass(resMethod->clazz))
{
assert(dvmCheckException(dvmThreadSelf()));
return NULL;
} else {
assert(!dvmCheckException(dvmThreadSelf()));
}
} else {
/*
* Edge case: if the <clinit> for a class creates an instance
* of itself, we will call <init> on a class that is still being
* initialized by us.
*/
assert(dvmIsClassInitialized(resMethod->clazz) ||
dvmIsClassInitializing(resMethod->clazz));
}
/*
* The class is initialized, the method has been found. Add a pointer
* to our data structure so we don't have to jump through the hoops again.
*/
dvmDexSetResolvedMethod(pDvmDex, methodIdx, resMethod);
return resMethod;
}
/*
* Alternate version of dvmResolveMethod().
*
* Doesn't throw exceptions, and checks access on every lookup.
*
* On failure, returns NULL, and sets *pFailure if pFailure is not NULL.
*/
Method* dvmOptResolveMethod(ClassObject* referrer, u4 methodIdx,
MethodType methodType, VerifyError* pFailure)
{
DvmDex* pDvmDex = referrer->pDvmDex;
Method* resMethod;
assert(methodType == METHOD_DIRECT ||
methodType == METHOD_VIRTUAL ||
methodType == METHOD_STATIC);
LOGVV("--- resolving method %u (referrer=%s)", methodIdx,
referrer->descriptor);
resMethod = dvmDexGetResolvedMethod(pDvmDex, methodIdx);
if (resMethod == NULL) {
const DexMethodId* pMethodId;
ClassObject* resClass;
pMethodId = dexGetMethodId(pDvmDex->pDexFile, methodIdx);
resClass = dvmOptResolveClass(referrer, pMethodId->classIdx, pFailure);
if (resClass == NULL) {
/*
* Can't find the class that the method is a part of, or don't
* have permission to access the class.
*/
ALOGV("DexOpt: can't find called method's class (?.%s)",
dexStringById(pDvmDex->pDexFile, pMethodId->nameIdx));
if (pFailure != NULL) { assert(!VERIFY_OK(*pFailure)); }
return NULL;
}
if (dvmIsInterfaceClass(resClass)) {
/* method is part of an interface; this is wrong method for that */
ALOGW("DexOpt: method is in an interface");
if (pFailure != NULL)
*pFailure = VERIFY_ERROR_GENERIC;
return NULL;
}
/*
* We need to chase up the class hierarchy to find methods defined
* in super-classes. (We only want to check the current class
* if we're looking for a constructor.)
*/
DexProto proto;
dexProtoSetFromMethodId(&proto, pDvmDex->pDexFile, pMethodId);
if (methodType == METHOD_DIRECT) {
resMethod = dvmFindDirectMethod(resClass,
dexStringById(pDvmDex->pDexFile, pMethodId->nameIdx), &proto);
} else {
/* METHOD_STATIC or METHOD_VIRTUAL */
resMethod = dvmFindMethodHier(resClass,
dexStringById(pDvmDex->pDexFile, pMethodId->nameIdx), &proto);
}
if (resMethod == NULL) {
ALOGV("DexOpt: couldn't find method '%s'",
dexStringById(pDvmDex->pDexFile, pMethodId->nameIdx));
if (pFailure != NULL)
*pFailure = VERIFY_ERROR_NO_METHOD;
return NULL;
}
if (methodType == METHOD_STATIC) {
if (!dvmIsStaticMethod(resMethod)) {
ALOGD("DexOpt: wanted static, got instance for method %s.%s",
resClass->descriptor, resMethod->name);
if (pFailure != NULL)
*pFailure = VERIFY_ERROR_CLASS_CHANGE;
return NULL;
}
} else if (methodType == METHOD_VIRTUAL) {
if (dvmIsStaticMethod(resMethod)) {
ALOGD("DexOpt: wanted instance, got static for method %s.%s",
resClass->descriptor, resMethod->name);
if (pFailure != NULL)
*pFailure = VERIFY_ERROR_CLASS_CHANGE;
return NULL;
}
}
/* see if this is a pure-abstract method */
if (dvmIsAbstractMethod(resMethod) && !dvmIsAbstractClass(resClass)) {
ALOGW("DexOpt: pure-abstract method '%s' in %s",
dexStringById(pDvmDex->pDexFile, pMethodId->nameIdx),
resClass->descriptor);
if (pFailure != NULL)
*pFailure = VERIFY_ERROR_GENERIC;
return NULL;
}
/*
* Add it to the resolved table so we're faster on the next lookup.
*
* We can only do this for static methods if we're not in "dexopt",
* because the presence of a valid value in the resolution table
* implies that the class containing the static field has been
* initialized.
*/
if (methodType != METHOD_STATIC || gDvm.optimizing)
dvmDexSetResolvedMethod(pDvmDex, methodIdx, resMethod);
}
LOGVV("--- found method %d (%s.%s)",
methodIdx, resMethod->clazz->descriptor, resMethod->name);
/* access allowed? */
tweakLoader(referrer, resMethod->clazz);
bool allowed = dvmCheckMethodAccess(referrer, resMethod);
untweakLoader(referrer, resMethod->clazz);
if (!allowed) {
IF_ALOGI() {
char* desc = dexProtoCopyMethodDescriptor(&resMethod->prototype);
ALOGI("DexOpt: illegal method access (call %s.%s %s from %s)",
resMethod->clazz->descriptor, resMethod->name, desc,
referrer->descriptor);
free(desc);
}
/*
* Optimize instructions in a method.
*
* This does a single pass through the code, examining each instruction.
*
* This is not expected to fail if the class was successfully verified.
* The only significant failure modes on unverified code occur when an
* "essential" update fails, but we can't generally identify those: if we
* can't look up a field, we can't know if the field access was supposed
* to be handled as volatile.
*
* Instead, we give it our best effort, and hope for the best. For 100%
* reliability, only optimize a class after verification succeeds.
*/
static void optimizeMethod(Method* method, bool essentialOnly)
{
bool needRetBar, forSmp;
u4 insnsSize;
u2* insns;
if (dvmIsNativeMethod(method) || dvmIsAbstractMethod(method))
return;
forSmp = gDvm.dexOptForSmp;
needRetBar = needsReturnBarrier(method);
insns = (u2*) method->insns;
assert(insns != NULL);
insnsSize = dvmGetMethodInsnsSize(method);
while (insnsSize > 0) {
Opcode opc, quickOpc, volatileOpc;
size_t width;
bool matched = true;
opc = dexOpcodeFromCodeUnit(*insns);
width = dexGetWidthFromInstruction(insns);
volatileOpc = OP_NOP;
/*
* Each instruction may have:
* - "volatile" replacement
* - may be essential or essential-on-SMP
* - correctness replacement
* - may be essential or essential-on-SMP
* - performance replacement
* - always non-essential
*
* Replacements are considered in the order shown, and the first
* match is applied. For example, iget-wide will convert to
* iget-wide-volatile rather than iget-wide-quick if the target
* field is volatile.
*/
/*
* essential substitutions:
* {iget,iput,sget,sput}-wide --> {op}-wide-volatile
* invoke-direct[/range] --> invoke-object-init/range
*
* essential-on-SMP substitutions:
* {iget,iput,sget,sput}-* --> {op}-volatile
* return-void --> return-void-barrier
*
* non-essential substitutions:
* {iget,iput}-* --> {op}-quick
*
* TODO: might be time to merge this with the other two switches
*/
switch (opc) {
case OP_IGET:
case OP_IGET_BOOLEAN:
case OP_IGET_BYTE:
case OP_IGET_CHAR:
case OP_IGET_SHORT:
quickOpc = OP_IGET_QUICK;
if (forSmp)
volatileOpc = OP_IGET_VOLATILE;
goto rewrite_inst_field;
case OP_IGET_WIDE:
quickOpc = OP_IGET_WIDE_QUICK;
volatileOpc = OP_IGET_WIDE_VOLATILE;
goto rewrite_inst_field;
case OP_IGET_OBJECT:
quickOpc = OP_IGET_OBJECT_QUICK;
if (forSmp)
volatileOpc = OP_IGET_OBJECT_VOLATILE;
goto rewrite_inst_field;
case OP_IPUT:
case OP_IPUT_BOOLEAN:
case OP_IPUT_BYTE:
case OP_IPUT_CHAR:
case OP_IPUT_SHORT:
quickOpc = OP_IPUT_QUICK;
if (forSmp)
volatileOpc = OP_IPUT_VOLATILE;
goto rewrite_inst_field;
case OP_IPUT_WIDE:
quickOpc = OP_IPUT_WIDE_QUICK;
volatileOpc = OP_IPUT_WIDE_VOLATILE;
goto rewrite_inst_field;
case OP_IPUT_OBJECT:
quickOpc = OP_IPUT_OBJECT_QUICK;
if (forSmp)
volatileOpc = OP_IPUT_OBJECT_VOLATILE;
/* fall through */
rewrite_inst_field:
if (essentialOnly)
quickOpc = OP_NOP; /* if essential-only, no "-quick" sub */
if (quickOpc != OP_NOP || volatileOpc != OP_NOP)
rewriteInstField(method, insns, quickOpc, volatileOpc);
break;
case OP_SGET:
case OP_SGET_BOOLEAN:
case OP_SGET_BYTE:
case OP_SGET_CHAR:
case OP_SGET_SHORT:
if (forSmp)
volatileOpc = OP_SGET_VOLATILE;
goto rewrite_static_field;
case OP_SGET_WIDE:
volatileOpc = OP_SGET_WIDE_VOLATILE;
goto rewrite_static_field;
case OP_SGET_OBJECT:
if (forSmp)
volatileOpc = OP_SGET_OBJECT_VOLATILE;
goto rewrite_static_field;
case OP_SPUT:
case OP_SPUT_BOOLEAN:
case OP_SPUT_BYTE:
case OP_SPUT_CHAR:
case OP_SPUT_SHORT:
if (forSmp)
volatileOpc = OP_SPUT_VOLATILE;
goto rewrite_static_field;
case OP_SPUT_WIDE:
volatileOpc = OP_SPUT_WIDE_VOLATILE;
goto rewrite_static_field;
case OP_SPUT_OBJECT:
if (forSmp)
volatileOpc = OP_SPUT_OBJECT_VOLATILE;
/* fall through */
rewrite_static_field:
if (volatileOpc != OP_NOP)
rewriteStaticField(method, insns, volatileOpc);
break;
case OP_INVOKE_DIRECT:
case OP_INVOKE_DIRECT_RANGE:
if (!rewriteInvokeObjectInit(method, insns)) {
/* may want to try execute-inline, below */
matched = false;
}
break;
case OP_RETURN_VOID:
if (needRetBar)
rewriteReturnVoid(method, insns);
break;
default:
matched = false;
break;
}
/*
* non-essential substitutions:
* invoke-{virtual,direct,static}[/range] --> execute-inline
* invoke-{virtual,super}[/range] --> invoke-*-quick
*/
if (!matched && !essentialOnly) {
switch (opc) {
case OP_INVOKE_VIRTUAL:
if (!rewriteExecuteInline(method, insns, METHOD_VIRTUAL)) {
rewriteVirtualInvoke(method, insns,
OP_INVOKE_VIRTUAL_QUICK);
}
break;
case OP_INVOKE_VIRTUAL_RANGE:
if (!rewriteExecuteInlineRange(method, insns, METHOD_VIRTUAL)) {
rewriteVirtualInvoke(method, insns,
OP_INVOKE_VIRTUAL_QUICK_RANGE);
}
break;
case OP_INVOKE_SUPER:
rewriteVirtualInvoke(method, insns, OP_INVOKE_SUPER_QUICK);
break;
case OP_INVOKE_SUPER_RANGE:
rewriteVirtualInvoke(method, insns, OP_INVOKE_SUPER_QUICK_RANGE);
break;
case OP_INVOKE_DIRECT:
rewriteExecuteInline(method, insns, METHOD_DIRECT);
break;
case OP_INVOKE_DIRECT_RANGE:
rewriteExecuteInlineRange(method, insns, METHOD_DIRECT);
break;
case OP_INVOKE_STATIC:
rewriteExecuteInline(method, insns, METHOD_STATIC);
break;
case OP_INVOKE_STATIC_RANGE:
rewriteExecuteInlineRange(method, insns, METHOD_STATIC);
break;
default:
/* nothing to do for this instruction */
;
}
}
assert(width > 0);
assert(width <= insnsSize);
assert(width == dexGetWidthFromInstruction(insns));
insns += width;
insnsSize -= width;
}
assert(insnsSize == 0);
}
/*
* Perform verification on a single method.
*
* We do this in three passes:
* (1) Walk through all code units, determining instruction lengths.
* (2) Do static checks, including branch target and operand validation.
* (3) Do structural checks, including data-flow analysis.
*
* Some checks may be bypassed depending on the verification mode. We can't
* turn this stuff off completely if we want to do "exact" GC.
*
* - operands of getfield, putfield, getstatic, putstatic must be valid
* - operands of method invocation instructions must be valid
*
* - code array must not be empty
* - (N/A) code_length must be less than 65536
* - opcode of first instruction begins at index 0
* - only documented instructions may appear
* - each instruction follows the last
* - (below) last byte of last instruction is at (code_length-1)
*/
static bool verifyMethod(Method* meth, int verifyFlags)
{
bool result = false;
UninitInstanceMap* uninitMap = NULL;
InsnFlags* insnFlags = NULL;
int i, newInstanceCount;
/*
* If there aren't any instructions, make sure that's expected, then
* exit successfully. Note: meth->insns gets set to a native function
* pointer on first call.
*/
if (dvmGetMethodInsnsSize(meth) == 0) {
if (!dvmIsNativeMethod(meth) && !dvmIsAbstractMethod(meth)) {
LOG_VFY_METH(meth,
"VFY: zero-length code in concrete non-native method\n");
goto bail;
}
goto success;
}
/*
* Sanity-check the register counts. ins + locals = registers, so make
* sure that ins <= registers.
*/
if (meth->insSize > meth->registersSize) {
LOG_VFY_METH(meth, "VFY: bad register counts (ins=%d regs=%d)\n",
meth->insSize, meth->registersSize);
goto bail;
}
/*
* Allocate and populate an array to hold instruction data.
*
* TODO: Consider keeping a reusable pre-allocated array sitting
* around for smaller methods.
*/
insnFlags = (InsnFlags*)
calloc(dvmGetMethodInsnsSize(meth), sizeof(InsnFlags));
if (insnFlags == NULL)
goto bail;
/*
* Compute the width of each instruction and store the result in insnFlags.
* Count up the #of occurrences of new-instance instructions while we're
* at it.
*/
if (!dvmComputeCodeWidths(meth, insnFlags, &newInstanceCount))
goto bail;
/*
* Allocate a map to hold the classes of uninitialized instances.
*/
uninitMap = dvmCreateUninitInstanceMap(meth, insnFlags, newInstanceCount);
if (uninitMap == NULL)
goto bail;
/*
* Set the "in try" flags for all instructions guarded by a "try" block.
*/
if (!dvmSetTryFlags(meth, insnFlags))
goto bail;
/*
* Perform static instruction verification.
*/
if (!verifyInstructions(meth, insnFlags, verifyFlags))
goto bail;
/*
* Do code-flow analysis. Do this after verifying the branch targets
* so we don't need to worry about it here.
*
* If there are no registers, we don't need to do much in the way of
* analysis, but we still need to verify that nothing actually tries
* to use a register.
*/
if (!dvmVerifyCodeFlow(meth, insnFlags, uninitMap)) {
//LOGD("+++ %s failed code flow\n", meth->name);
goto bail;
}
success:
result = true;
bail:
dvmFreeUninitInstanceMap(uninitMap);
free(insnFlags);
return result;
}
