[Kernel] New event signalling, better Mootex

include/kernel/kernel_types.hpp

@@ -26,6 +26,9 @@ namespace SVCResult {
 
         // Returned when a thread stops waiting due to timing out
         Timeout = 0x9401BFE,
+
+        // Returned when a thread releases a mutex it does not own
+        InvalidMutexRelease = 0xD8E0041F
 	};
 }
 
@@ -171,9 +174,10 @@ static const char* kernelObjectTypeToString(KernelObjectType t) {
 struct Mutex {
     u64 waitlist;           // Refer to the getWaitlist function below for documentation
     Handle ownerThread = 0; // Index of the thread that holds the mutex if it's locked
+    u32 lockCount; // Number of times this mutex has been locked by its daddy. 0 = not locked
     bool locked;
 
-    Mutex(bool lock = false) : locked(lock), waitlist(0) {}
+    Mutex(bool lock = false) : locked(lock), waitlist(0), lockCount(0) {}
 };
 
 struct Semaphore {

src/core/kernel/events.cpp

@@ -1,5 +1,6 @@
 #include "kernel.hpp"
 #include "cpu.hpp"
+#include <bit>
 #include <utility>
 
 const char* Kernel::resetTypeToString(u32 type) {
@@ -27,29 +28,39 @@ bool Kernel::signalEvent(Handle handle) {
 	Event* event = object->getData<Event>();
 	event->fired = true;
 
-	if (event->waitlist != 0) {
-		Helpers::panic("Tried to signal event with a waitlist");
+	// One shot events go back to being not fired once they wake up one or more thread
+	if (event->waitlist != 0 && event->resetType == ResetType::OneShot) {
+		event->fired = false;
 	}
-	/*
-	switch (event->resetType) {
-		case ResetType::OneShot:
-			for (int i = 0; i < threadCount; i++) {
-				Thread& t = threads[i];
 
-				if (t.status == ThreadStatus::WaitSync1 && t.waitList[0] == handle) {
-					t.status = ThreadStatus::Ready;
-					break;
-				}
-				else if (t.status == ThreadStatus::WaitSyncAll) {
-					Helpers::panic("Trying to SignalEvent when a thread is waiting on multiple objects");
-				}
-			}
-			break;
+	// Wake up every single thread in the waitlist using a bit scanning algorithm
+	while (event->waitlist != 0) {
+		const uint index = std::countr_zero(event->waitlist); // Get one of the set bits to see which thread is waiting
+		event->waitlist ^= (1ull << index); // Remove thread from waitlist by toggling its bit
 
-		default:
-			Helpers::panic("Signaled event of unimplemented type: %d", event->resetType);
+		// Get the thread we'll be signalling
+		Thread& t = threads[index];
+		switch (t.status) {
+			case ThreadStatus::WaitSync1:
+				t.status = ThreadStatus::Ready;
+				break;
+
+			case ThreadStatus::WaitSyncAny:
+				t.status = ThreadStatus::Ready;
+				// Get the index of the event in the object's waitlist, write it to r1
+				for (size_t i = 0; i < t.waitList.size(); i++) {
+					if (t.waitList[i] == handle) {
+						t.gprs[1] = i;
+						break;
+					}
+				}
+				break;
+
+			case ThreadStatus::WaitSyncAll:
+				Helpers::panic("SignalEvent: Thread on WaitSyncAll");
+				break;
+		}
 	}
-	*/
 
 	return true;
 }

src/core/kernel/kernel.cpp

@@ -15,6 +15,7 @@ Kernel::Kernel(CPU& cpu, Memory& mem, GPU& gpu)
 		t.index = i;
 		t.tlsBase = VirtualAddrs::TLSBase + i * VirtualAddrs::TLSSize;
 		t.status = ThreadStatus::Dead;
+		t.waitList.clear();
 		t.waitList.reserve(10); // Reserve some space for the wait list to avoid further memory allocs later
 		// The state below isn't necessary to initialize but we do it anyways out of caution
 		t.outPointer = 0;

src/core/kernel/threads.cpp

@@ -165,18 +165,26 @@ Handle Kernel::makeMutex(bool locked) {
 	Handle ret = makeObject(KernelObjectType::Mutex);
 	objects[ret].data = new Mutex(locked);
 
-	// If the mutex is initially locked, store the index of the thread that owns it
+	// If the mutex is initially locked, store the index of the thread that owns it and set lock count to 1
 	if (locked) {
-		objects[ret].getData<Mutex>()->ownerThread = currentThreadIndex;
+		Mutex* moo = objects[ret].getData<Mutex>();
+		moo->ownerThread = currentThreadIndex;
+		moo->lockCount = 1;
 	}
 
 	return ret;
 }
 
 void Kernel::releaseMutex(Mutex* moo) {
-	moo->locked = false;
-	if (moo->waitlist != 0) {
-		Helpers::panic("Mutex got freed while it's got more threads waiting for it. Must make a new thread claim it.");
+	// TODO: Assert lockCount > 0 before release, maybe. The SVC should be safe at least.
+	moo->lockCount--; // Decrement lock count
+
+	// If the lock count reached 0 then the thread no longer owns the mootex and it can be given to a new one
+	if (moo->lockCount == 0) {
+		moo->locked = false;
+		if (moo->waitlist != 0) {
+			Helpers::panic("Mutex got freed while it's got more threads waiting for it. Must make a new thread claim it.");
+		}
 	}
 }
 
@@ -200,7 +208,10 @@ void Kernel::acquireSyncObject(KernelObject* object, const Thread& thread) {
 	switch (object->type) {
 		case KernelObjectType::Mutex: {
 			Mutex* moo = object->getData<Mutex>();
-			moo->locked = true;
+			moo->locked = true; // Set locked to true, whether it's false or not because who cares
+			// Increment lock count by 1. If a thread acquires a mootex multiple times, it needs to release it until count == 0
+			// For the mootex to be free.
+			moo->lockCount++;
 			moo->ownerThread = thread.index;
 			break;
 		}
@@ -375,7 +386,8 @@ void Kernel::svcReleaseMutex() {
 	Mutex* moo = object->getData<Mutex>();
 	// A thread can't release a mutex it does not own
 	if (!moo->locked || moo->ownerThread != currentThreadIndex) {
-		Helpers::panic("[ReleaseMutex] Tried to release mutex that does not belong to thread");
+		regs[0] = SVCResult::InvalidMutexRelease;
+		return;
 	}
 
 	releaseMutex(moo);