/*
* We need the JDWP thread to hold off on doing stuff while we post an
* event and then suspend ourselves.
*
* Call this with a threadId of zero if you just want to wait for the
* current thread operation to complete.
*
* This could go to sleep waiting for another thread, so it's important
* that the thread be marked as VMWAIT before calling here.
*/
void dvmJdwpSetWaitForEventThread(JdwpState* state, ObjectId threadId)
{
bool waited = false;
/* this is held for very brief periods; contention is unlikely */
dvmDbgLockMutex(&state->eventThreadLock);
/*
* If another thread is already doing stuff, wait for it. This can
* go to sleep indefinitely.
*/
while (state->eventThreadId != 0) {
ALOGV("event in progress (0x%llx), 0x%llx sleeping",
state->eventThreadId, threadId);
waited = true;
dvmDbgCondWait(&state->eventThreadCond, &state->eventThreadLock);
}
if (waited || threadId != 0)
ALOGV("event token grabbed (0x%llx)", threadId);
if (threadId != 0)
state->eventThreadId = threadId;
dvmDbgUnlockMutex(&state->eventThreadLock);
}
/*
* Get the next "event" serial number. We use this in the response to
* message type EventRequest.Set.
*/
u4 dvmJdwpNextEventSerial(JdwpState* state)
{
dvmDbgLockMutex(&state->serialLock);
u4 result = state->eventSerial++;
dvmDbgUnlockMutex(&state->serialLock);
return result;
}
/*
* Three possibilities:
* SP_NONE - do nothing
* SP_EVENT_THREAD - suspend ourselves
* SP_ALL - suspend everybody except JDWP support thread
*/
static void suspendByPolicy(JdwpState* state, JdwpSuspendPolicy suspendPolicy)
{
if (suspendPolicy == SP_NONE)
return;
if (suspendPolicy == SP_ALL) {
dvmDbgSuspendVM(true);
} else {
assert(suspendPolicy == SP_EVENT_THREAD);
}
/* this is rare but possible -- see CLASS_PREPARE handling */
if (dvmDbgGetThreadSelfId() == state->debugThreadId) {
ALOGI("NOTE: suspendByPolicy not suspending JDWP thread");
return;
}
DebugInvokeReq* pReq = dvmDbgGetInvokeReq();
while (true) {
pReq->ready = true;
dvmDbgSuspendSelf();
pReq->ready = false;
/*
* The JDWP thread has told us (and possibly all other threads) to
* resume. See if it has left anything in our DebugInvokeReq mailbox.
*/
if (!pReq->invokeNeeded) {
/*LOGD("suspendByPolicy: no invoke needed");*/
break;
}
/* grab this before posting/suspending again */
dvmJdwpSetWaitForEventThread(state, dvmDbgGetThreadSelfId());
/* leave pReq->invokeNeeded raised so we can check reentrancy */
ALOGV("invoking method...");
dvmDbgExecuteMethod(pReq);
pReq->err = ERR_NONE;
/* clear this before signaling */
pReq->invokeNeeded = false;
ALOGV("invoke complete, signaling and self-suspending");
dvmDbgLockMutex(&pReq->lock);
dvmDbgCondSignal(&pReq->cv);
dvmDbgUnlockMutex(&pReq->lock);
}
}
/*
* Clear the threadId and signal anybody waiting.
*/
void dvmJdwpClearWaitForEventThread(JdwpState* state)
{
/*
* Grab the mutex. Don't try to go in/out of VMWAIT mode, as this
* function is called by dvmSuspendSelf(), and the transition back
* to RUNNING would confuse it.
*/
dvmDbgLockMutex(&state->eventThreadLock);
assert(state->eventThreadId != 0);
ALOGV("cleared event token (0x%llx)", state->eventThreadId);
state->eventThreadId = 0;
dvmDbgCondSignal(&state->eventThreadCond);
dvmDbgUnlockMutex(&state->eventThreadLock);
}
/*
* Unlock the "event" mutex.
*/
static void unlockEventMutex(JdwpState* state)
{
dvmDbgUnlockMutex(&state->eventLock);
}
/*
* Initialize JDWP.
*
* Does not return until JDWP thread is running, but may return before
* the thread is accepting network connections.
*/
JdwpState* dvmJdwpStartup(const JdwpStartupParams* pParams)
{
JdwpState* state = NULL;
/* comment this out when debugging JDWP itself */
android_setMinPriority(LOG_TAG, ANDROID_LOG_DEBUG);
state = (JdwpState*) calloc(1, sizeof(JdwpState));
state->params = *pParams;
state->requestSerial = 0x10000000;
state->eventSerial = 0x20000000;
dvmDbgInitMutex(&state->threadStartLock);
dvmDbgInitMutex(&state->attachLock);
dvmDbgInitMutex(&state->serialLock);
dvmDbgInitMutex(&state->eventLock);
state->eventThreadId = 0;
dvmDbgInitMutex(&state->eventThreadLock);
dvmDbgInitCond(&state->threadStartCond);
dvmDbgInitCond(&state->attachCond);
dvmDbgInitCond(&state->eventThreadCond);
switch (pParams->transport) {
case kJdwpTransportSocket:
// LOGD("prepping for JDWP over TCP\n");
state->transport = dvmJdwpSocketTransport();
break;
case kJdwpTransportAndroidAdb:
// LOGD("prepping for JDWP over ADB\n");
state->transport = dvmJdwpAndroidAdbTransport();
/* TODO */
break;
default:
LOGE("Unknown transport %d\n", pParams->transport);
assert(false);
goto fail;
}
if (!dvmJdwpNetStartup(state, pParams))
goto fail;
/*
* Grab a mutex or two before starting the thread. This ensures they
* won't signal the cond var before we're waiting.
*/
dvmDbgLockMutex(&state->threadStartLock);
if (pParams->suspend)
dvmDbgLockMutex(&state->attachLock);
/*
* We have bound to a port, or are trying to connect outbound to a
* debugger. Create the JDWP thread and let it continue the mission.
*/
if (!dvmCreateInternalThread(&state->debugThreadHandle, "JDWP",
jdwpThreadStart, state))
{
/* state is getting tossed, but unlock these anyway for cleanliness */
dvmDbgUnlockMutex(&state->threadStartLock);
if (pParams->suspend)
dvmDbgUnlockMutex(&state->attachLock);
goto fail;
}
/*
* Wait until the thread finishes basic initialization.
* TODO: cond vars should be waited upon in a loop
*/
dvmDbgCondWait(&state->threadStartCond, &state->threadStartLock);
dvmDbgUnlockMutex(&state->threadStartLock);
/*
* For suspend=y, wait for the debugger to connect to us or for us to
* connect to the debugger.
*
* The JDWP thread will signal us when it connects successfully or
* times out (for timeout=xxx), so we have to check to see what happened
* when we wake up.
*/
if (pParams->suspend) {
dvmChangeStatus(NULL, THREAD_VMWAIT);
dvmDbgCondWait(&state->attachCond, &state->attachLock);
dvmDbgUnlockMutex(&state->attachLock);
dvmChangeStatus(NULL, THREAD_RUNNING);
if (!dvmJdwpIsActive(state)) {
LOGE("JDWP connection failed\n");
goto fail;
}
LOGI("JDWP connected\n");
/*
* Ordinarily we would pause briefly to allow the debugger to set
* breakpoints and so on, but for "suspend=y" the VM init code will
* pause the VM when it sends the VM_START message.
*/
}
return state;
fail:
dvmJdwpShutdown(state); // frees state
return NULL;
}
/*
* Entry point for JDWP thread. The thread was created through the VM
* mechanisms, so there is a java/lang/Thread associated with us.
*/
static void* jdwpThreadStart(void* arg)
{
JdwpState* state = (JdwpState*) arg;
LOGV("JDWP: thread running\n");
/*
* Finish initializing "state", then notify the creating thread that
* we're running.
*/
state->debugThreadHandle = dvmThreadSelf()->handle;
state->run = true;
android_atomic_release_store(true, &state->debugThreadStarted);
dvmDbgLockMutex(&state->threadStartLock);
dvmDbgCondBroadcast(&state->threadStartCond);
dvmDbgUnlockMutex(&state->threadStartLock);
/* set the thread state to VMWAIT so GCs don't wait for us */
dvmDbgThreadWaiting();
/*
* Loop forever if we're in server mode, processing connections. In
* non-server mode, we bail out of the thread when the debugger drops
* us.
*
* We broadcast a notification when a debugger attaches, after we
* successfully process the handshake.
*/
while (state->run) {
bool first;
if (state->params.server) {
/*
* Block forever, waiting for a connection. To support the
* "timeout=xxx" option we'll need to tweak this.
*/
if (!dvmJdwpAcceptConnection(state))
break;
} else {
/*
* If we're not acting as a server, we need to connect out to the
* debugger. To support the "timeout=xxx" option we need to
* have a timeout if the handshake reply isn't received in a
* reasonable amount of time.
*/
if (!dvmJdwpEstablishConnection(state)) {
/* wake anybody who was waiting for us to succeed */
dvmDbgLockMutex(&state->attachLock);
dvmDbgCondBroadcast(&state->attachCond);
dvmDbgUnlockMutex(&state->attachLock);
break;
}
}
/* prep debug code to handle the new connection */
dvmDbgConnected();
/* process requests until the debugger drops */
first = true;
while (true) {
// sanity check -- shouldn't happen?
if (dvmThreadSelf()->status != THREAD_VMWAIT) {
LOGE("JDWP thread no longer in VMWAIT (now %d); resetting\n",
dvmThreadSelf()->status);
dvmDbgThreadWaiting();
}
if (!dvmJdwpProcessIncoming(state)) /* blocking read */
break;
if (first && !dvmJdwpAwaitingHandshake(state)) {
/* handshake worked, tell the interpreter that we're active */
first = false;
/* set thread ID; requires object registry to be active */
state->debugThreadId = dvmDbgGetThreadSelfId();
/* wake anybody who's waiting for us */
dvmDbgLockMutex(&state->attachLock);
dvmDbgCondBroadcast(&state->attachCond);
dvmDbgUnlockMutex(&state->attachLock);
}
}
dvmJdwpCloseConnection(state);
if (state->ddmActive) {
state->ddmActive = false;
/* broadcast the disconnect; must be in RUNNING state */
dvmDbgThreadRunning();
dvmDbgDdmDisconnected();
dvmDbgThreadWaiting();
}
/* release session state, e.g. remove breakpoint instructions */
dvmJdwpResetState(state);
/* tell the interpreter that the debugger is no longer around */
dvmDbgDisconnected();
/* if we had threads suspended, resume them now */
dvmUndoDebuggerSuspensions();
/* if we connected out, this was a one-shot deal */
if (!state->params.server)
state->run = false;
}
/* back to running, for thread shutdown */
dvmDbgThreadRunning();
LOGV("JDWP: thread exiting\n");
return NULL;
}