C++ SAVEAREA_FROM_FP函数代码示例

/*
 * Pop one frame pushed on by JNI PushLocalFrame.
 *
 * If we've gone too far, the previous frame is either a break frame or
 * an interpreted frame.  Either way, the method pointer won't match.
 */
bool dvmPopLocalFrame(Thread* self)
{
    StackSaveArea* saveBlock = SAVEAREA_FROM_FP(self->interpSave.curFrame);

    assert(!dvmIsBreakFrame((u4*)self->interpSave.curFrame));
    if (saveBlock->method != SAVEAREA_FROM_FP(saveBlock->prevFrame)->method) {
        /*
         * The previous frame doesn't have the same method pointer -- we've
         * been asked to pop too much.
         */
        assert(dvmIsBreakFrame((u4*)saveBlock->prevFrame) ||
               !dvmIsNativeMethod(
                       SAVEAREA_FROM_FP(saveBlock->prevFrame)->method));
        return false;
    }

    LOGVV("POP JNI local frame: removing %s, now %s",
        saveBlock->method->name,
        SAVEAREA_FROM_FP(saveBlock->prevFrame)->method->name);
    dvmPopJniLocals(self, saveBlock);
    self->interpSave.curFrame = saveBlock->prevFrame;
#ifdef WITH_OFFLOAD
    offStackFramePopped(self);
#endif

    return true;
}

/*
 * Get the calling frame.  Pass in the current fp.
 *
 * Skip "break" frames and reflection invoke frames.
 */
void* dvmGetCallerFP(const void* curFrame)
{
    void* caller = SAVEAREA_FROM_FP(curFrame)->prevFrame;
    StackSaveArea* saveArea;

retry:
    if (dvmIsBreakFrame((u4*)caller)) {
        /* pop up one more */
        caller = SAVEAREA_FROM_FP(caller)->prevFrame;
        if (caller == NULL)
            return NULL;        /* hit the top */

        /*
         * If we got here by java.lang.reflect.Method.invoke(), we don't
         * want to return Method's class loader.  Shift up one and try
         * again.
         */
        saveArea = SAVEAREA_FROM_FP(caller);
        if (dvmIsReflectionMethod(saveArea->method)) {
            caller = saveArea->prevFrame;
            assert(caller != NULL);
            goto retry;
        }
    }

    return caller;
}

/*
 * Fill a flat array of methods that comprise the current interpreter
 * stack trace.  Pass in the current frame ptr.  Break frames are
 * skipped, but reflection invocations are not.
 *
 * The current frame will be in element 0.
 */
void dvmFillStackTraceArray(const void* fp, const Method** array, size_t length)
{
    assert(fp != NULL);
    assert(array != NULL);
    size_t i = 0;
    while (fp != NULL) {
        if (!dvmIsBreakFrame((u4*)fp)) {
            assert(i < length);
            array[i++] = SAVEAREA_FROM_FP(fp)->method;
        }
        fp = SAVEAREA_FROM_FP(fp)->prevFrame;
    }
}

/*
 * Get the caller's caller's class.  Pass in the current fp.
 *
 * This is used by e.g. java.lang.Class, which wants to know about the
 * class loader of the method that called it.
 */
ClassObject* dvmGetCaller2Class(const void* curFrame)
{
    void* caller = SAVEAREA_FROM_FP(curFrame)->prevFrame;
    void* callerCaller;

    /* at the top? */
    if (dvmIsBreakFrame(caller) && SAVEAREA_FROM_FP(caller)->prevFrame == NULL)
        return NULL;

    /* go one more */
    callerCaller = dvmGetCallerFP(caller);
    if (callerCaller == NULL)
        return NULL;

    return SAVEAREA_FROM_FP(callerCaller)->method->clazz;
}

/*
 * Pop a frame we added.  There should be one method frame and one break
 * frame.
 *
 * If JNI Push/PopLocalFrame calls were mismatched, we might end up
 * popping multiple method frames before we find the break.
 *
 * Returns "false" if there was no frame to pop.
 */
static bool dvmPopFrame(Thread* self)
{
    StackSaveArea* saveBlock;

    if (self->interpSave.curFrame == NULL)
        return false;

    saveBlock = SAVEAREA_FROM_FP(self->interpSave.curFrame);
    assert(!dvmIsBreakFrame((u4*)self->interpSave.curFrame));

    /*
     * Remove everything up to the break frame.  If this was a call into
     * native code, pop the JNI local references table.
     */
    while (saveBlock->prevFrame != NULL && saveBlock->method != NULL) {
        /* probably a native->native JNI call */

        if (dvmIsNativeMethod(saveBlock->method)) {
            LOGVV("Popping JNI stack frame for %s.%s%s",
                saveBlock->method->clazz->descriptor,
                saveBlock->method->name,
                (SAVEAREA_FROM_FP(saveBlock->prevFrame)->method == NULL) ?
                "" : " (JNI local)");
            dvmPopJniLocals(self, saveBlock);
        }

        saveBlock = SAVEAREA_FROM_FP(saveBlock->prevFrame);
    }
    if (saveBlock->method != NULL) {
        ALOGE("PopFrame missed the break");
        assert(false);
        dvmAbort();     // stack trashed -- nowhere to go in this thread
    }

    LOGVV("POP frame: cur=%p new=%p",
        self->interpSave.curFrame, saveBlock->prevFrame);

    self->interpSave.curFrame = saveBlock->prevFrame;

#ifdef WITH_OFFLOAD
    offStackFramePopped(self);
    self->breakFrames--;
    CHECK_BREAK_FRAMES();
#endif
    return true;
}

/*
 * Get the caller's caller's caller's class.  Pass in the current fp.
 *
 * This is used by e.g. java.lang.Class, which wants to know about the
 * class loader of the method that called it.
 */
ClassObject* dvmGetCaller3Class(const void* curFrame)
{
    void* caller = SAVEAREA_FROM_FP(curFrame)->prevFrame;
    int i;

    /* at the top? */
    if (dvmIsBreakFrame(caller) && SAVEAREA_FROM_FP(caller)->prevFrame == NULL)
        return NULL;

    /* Walk up two frames if possible. */
    for (i = 0; i < 2; i++) {
        caller = dvmGetCallerFP(caller);
        if (caller == NULL)
            return NULL;
    }
    
    return SAVEAREA_FROM_FP(caller)->method->clazz;
}

/*
 * Pop a frame we added.  There should be one method frame and one break
 * frame.
 *
 * If JNI Push/PopLocalFrame calls were mismatched, we might end up
 * popping multiple method frames before we find the break.
 *
 * Returns "false" if there was no frame to pop.
 */
static bool dvmPopFrame(Thread* self)
{
    StackSaveArea* saveBlock;

    if (self->curFrame == NULL)
        return false;

    saveBlock = SAVEAREA_FROM_FP(self->curFrame);
    assert(!dvmIsBreakFrame(self->curFrame));

    /*
     * Remove everything up to the break frame.  If this was a call into
     * native code, pop the JNI local references table.
     */
    while (saveBlock->prevFrame != NULL && saveBlock->method != NULL) {
        /* probably a native->native JNI call */

        if (dvmIsNativeMethod(saveBlock->method)) {
            LOGVV("Popping JNI stack frame for %s.%s%s\n",
                saveBlock->method->clazz->descriptor,
                saveBlock->method->name,
                (SAVEAREA_FROM_FP(saveBlock->prevFrame)->method == NULL) ?
                "" : " (JNI local)");
            assert(saveBlock->xtra.localRefCookie != 0);
            //assert(saveBlock->xtra.localRefCookie >= self->jniLocalRefTable.table &&
            //    saveBlock->xtra.localRefCookie <=self->jniLocalRefTable.nextEntry);

            dvmPopJniLocals(self, saveBlock);
        }

        saveBlock = SAVEAREA_FROM_FP(saveBlock->prevFrame);
    }
    if (saveBlock->method != NULL) {
        LOGE("PopFrame missed the break\n");
        assert(false);
        dvmAbort();     // stack trashed -- nowhere to go in this thread
    }

    LOGVV("POP frame: cur=%p new=%p\n",
        self->curFrame, saveBlock->prevFrame);

    self->curFrame = saveBlock->prevFrame;
    return true;
}

/*
 * This is used by the JNI PushLocalFrame call.  We push a new frame onto
 * the stack that has no ins, outs, or locals, and no break frame above it.
 * It's strictly used for tracking JNI local refs, and will be popped off
 * by dvmPopFrame if it's not removed explicitly.
 */
bool dvmPushLocalFrame(Thread* self, const Method* method)
{
    StackSaveArea* saveBlock;
    int stackReq;
    u1* stackPtr;

    assert(dvmIsNativeMethod(method));

    stackReq = sizeof(StackSaveArea);       // regular frame

    assert(self->curFrame != NULL);
    stackPtr = (u1*) SAVEAREA_FROM_FP(self->curFrame);

    if (stackPtr - stackReq < self->interpStackEnd) {
        /* not enough space; let JNI throw the exception */
        LOGW("Stack overflow on PushLocal "
             "(req=%d top=%p cur=%p size=%d '%s')\n",
            stackReq, self->interpStackStart, self->curFrame,
            self->interpStackSize, method->name);
        dvmHandleStackOverflow(self, method);
        assert(dvmCheckException(self));
        return false;
    }

    /*
     * Shift the stack pointer down, leaving space for just the stack save
     * area for the break frame, then shift down farther for the full frame.
     */
    stackPtr -= sizeof(StackSaveArea);
    saveBlock = (StackSaveArea*) stackPtr;

#if !defined(NDEBUG) && !defined(PAD_SAVE_AREA)
    /* debug -- memset the new stack */
    memset(stackPtr, 0xaf, stackReq);
#endif
#ifdef EASY_GDB
    saveBlock->prevSave = FP_FROM_SAVEAREA(self->curFrame);
#endif

    saveBlock->prevFrame = self->curFrame;
    saveBlock->savedPc = NULL;                  // not required
#ifdef USE_INDIRECT_REF
    saveBlock->xtra.localRefCookie = self->jniLocalRefTable.segmentState.all;
#else
    saveBlock->xtra.localRefCookie = self->jniLocalRefTable.nextEntry;
#endif
    saveBlock->method = method;

    LOGVV("PUSH JNI local frame: old=%p new=%p (size=%d)\n",
        self->curFrame, FP_FROM_SAVEAREA(saveBlock),
        (u1*)self->curFrame - (u1*)FP_FROM_SAVEAREA(saveBlock));

    self->curFrame = FP_FROM_SAVEAREA(saveBlock);

    return true;
}

/*
 * Main interpreter loop.
 *
 * This was written with an ARM implementation in mind.
 */
void dvmInterpretPortable(Thread* self)
{
#if defined(EASY_GDB)
    StackSaveArea* debugSaveArea = SAVEAREA_FROM_FP(self->interpSave.curFrame);
#endif
    DvmDex* methodClassDex;     // curMethod->clazz->pDvmDex
    JValue retval;

    /* core state */
    const Method* curMethod;    // method we're interpreting
    const u2* pc;               // program counter
    u4* fp;                     // frame pointer
    u2 inst;                    // current instruction
    /* instruction decoding */
    u4 ref;                     // 16 or 32-bit quantity fetched directly
    u2 vsrc1, vsrc2, vdst;      // usually used for register indexes
    /* method call setup */
    const Method* methodToCall;
    bool methodCallRange;

    /* static computed goto table */
    DEFINE_GOTO_TABLE(handlerTable);

    /* copy state in */
    curMethod = self->interpSave.method;
    pc = self->interpSave.pc;
    fp = self->interpSave.curFrame;
    retval = self->interpSave.retval;   /* only need for kInterpEntryReturn? */

    methodClassDex = curMethod->clazz->pDvmDex;

    LOGVV("threadid=%d: %s.%s pc=%#x fp=%p",
        self->threadId, curMethod->clazz->descriptor, curMethod->name,
        pc - curMethod->insns, fp);

    /*
     * Handle any ongoing profiling and prep for debugging.
     */
    if (self->interpBreak.ctl.subMode != 0) {
        TRACE_METHOD_ENTER(self, curMethod);
        self->debugIsMethodEntry = true;   // Always true on startup
    }
    /*
     * DEBUG: scramble this to ensure we're not relying on it.
     */
    methodToCall = (const Method*) -1;

#if 0
    if (self->debugIsMethodEntry) {
        ILOGD("|-- Now interpreting %s.%s", curMethod->clazz->descriptor,
                curMethod->name);
        DUMP_REGS(curMethod, self->interpSave.curFrame, false);
    }
#endif

    FINISH(0);                  /* fetch and execute first instruction */

/*
 * Get the caller's class.  Pass in the current fp.
 *
 * This is used by e.g. java.lang.Class.
 */
ClassObject* dvmGetCallerClass(const void* curFrame)
{
    void* caller;

    caller = dvmGetCallerFP(curFrame);
    if (caller == NULL)
        return NULL;

    return SAVEAREA_FROM_FP(caller)->method->clazz;
}

/*
 * Compute the frame depth.
 *
 * Excludes "break" frames.
 */
int dvmComputeExactFrameDepth(const void* fp)
{
    int count = 0;

    for ( ; fp != NULL; fp = SAVEAREA_FROM_FP(fp)->prevFrame) {
        if (!dvmIsBreakFrame((u4*)fp))
            count++;
    }

    return count;
}

/*
 * Create a flat array of methods that comprise the current interpreter
 * stack trace.  Pass in the current frame ptr.
 *
 * Allocates a new array and fills it with method pointers.  Break frames
 * are skipped, but reflection invocations are not.  The caller must free
 * "*pArray".
 *
 * The current frame will be in element 0.
 *
 * Returns "true" on success, "false" on failure (e.g. malloc failed).
 */
bool dvmCreateStackTraceArray(const void* fp, const Method*** pArray,
    int* pLength)
{
    const Method** array;
    int idx, depth;

    depth = dvmComputeExactFrameDepth(fp);
    array = (const Method**) malloc(depth * sizeof(Method*));
    if (array == NULL)
        return false;

    for (idx = 0; fp != NULL; fp = SAVEAREA_FROM_FP(fp)->prevFrame) {
        if (!dvmIsBreakFrame(fp))
            array[idx++] = SAVEAREA_FROM_FP(fp)->method;
    }
    assert(idx == depth);

    *pArray = array;
    *pLength = depth;
    return true;
}

/*
 * Dump the StackSaveArea for the specified frame pointer.
 */
void dvmDumpFp(void* fp, StackSaveArea* otherSaveArea)
{
    StackSaveArea* saveArea = SAVEAREA_FROM_FP(fp);
    printf("StackSaveArea for fp %p [%p/%p]:\n", fp, saveArea, otherSaveArea);
#ifdef EASY_GDB
    printf("  prevSave=%p, prevFrame=%p savedPc=%p meth=%p curPc=%p\n",
        saveArea->prevSave, saveArea->prevFrame, saveArea->savedPc,
        saveArea->method, saveArea->xtra.currentPc);
#else
    printf("  prevFrame=%p savedPc=%p meth=%p curPc=%p fp[0]=0x%08x\n",
        saveArea->prevFrame, saveArea->savedPc,
        saveArea->method, saveArea->xtra.currentPc,
        *(u4*)fp);
#endif
}

static void crawlDalvikStack(Thread *thread, bool print)
{
    void *fp = thread->interpSave.curFrame;
    StackSaveArea* saveArea = NULL;
    int stackLevel = 0;

    /* Crawl the Dalvik stack frames to clear the returnAddr field */
    while (fp != NULL) {
        saveArea = SAVEAREA_FROM_FP(fp);
        stackLevel++;
        saveArea->returnAddr = NULL;
        assert(fp != saveArea->prevFrame);
        fp = saveArea->prevFrame;
    }
    /* Make sure the stack is fully unwound to the bottom */
    assert(saveArea == NULL ||
           (u1 *) (saveArea+1) == thread->interpStackStart);
}

/*
 * Open up the reserved area and throw an exception.  The reserved area
 * should only be needed to create and initialize the exception itself.
 *
 * If we already opened it and we're continuing to overflow, abort the VM.
 *
 * We have to leave the "reserved" area open until the "catch" handler has
 * finished doing its processing.  This is because the catch handler may
 * need to resolve classes, which requires calling into the class loader if
 * the classes aren't already in the "initiating loader" list.
 */
void dvmHandleStackOverflow(Thread* self, const Method* method)
{
    /*
     * Can we make the reserved area available?
     */
    if (self->stackOverflowed) {
        /*
         * Already did, nothing to do but bail.
         */
        LOGE("DalvikVM: double-overflow of stack in threadid=%d; aborting\n",
            self->threadId);
        dvmDumpThread(self, false);
        dvmAbort();
    }

    /* open it up to the full range */
    LOGI("threadid=%d: stack overflow on call to %s.%s:%s\n",
        self->threadId,
        method->clazz->descriptor, method->name, method->shorty);
    StackSaveArea* saveArea = SAVEAREA_FROM_FP(self->curFrame);
    LOGI("  method requires %d+%d+%d=%d bytes, fp is %p (%d left)\n",
        method->registersSize * 4, sizeof(StackSaveArea), method->outsSize * 4,
        (method->registersSize + method->outsSize) * 4 + sizeof(StackSaveArea),
        saveArea, (u1*) saveArea - self->interpStackEnd);
    LOGI("  expanding stack end (%p to %p)\n", self->interpStackEnd,
        self->interpStackStart - self->interpStackSize);
    //dvmDumpThread(self, false);
    self->interpStackEnd = self->interpStackStart - self->interpStackSize;
    self->stackOverflowed = true;

    /*
     * If we were trying to throw an exception when the stack overflowed,
     * we will blow up when doing the class lookup on StackOverflowError
     * because of the pending exception.  So, we clear it and make it
     * the cause of the SOE.
     */
    Object* excep = dvmGetException(self);
    if (excep != NULL) {
        LOGW("Stack overflow while throwing exception\n");
        dvmClearException(self);
    }
    dvmThrowChainedExceptionByClass(gDvm.classJavaLangStackOverflowError,
        NULL, excep);
}