From 7f2715d06ce10fc2c432e3ab4a4f56e28ac433eb Mon Sep 17 00:00:00 2001
From: wheremyfoodat <gponiris2004@gmail.com>
Date: Thu, 20 Apr 2023 22:24:36 +0300
Subject: [PATCH] [Kernel] Fix release mutex

---
 include/kernel/kernel.hpp   |  5 +++--
 src/core/kernel/kernel.cpp  |  4 ++--
 src/core/kernel/threads.cpp | 27 ++++++++++++++++++++++++---
 3 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/include/kernel/kernel.hpp b/include/kernel/kernel.hpp
index 3333923d..85adf952 100644
--- a/include/kernel/kernel.hpp
+++ b/include/kernel/kernel.hpp
@@ -73,6 +73,7 @@ private:
 	void rescheduleThreads();
 	bool canThreadRun(const Thread& t);
 	bool shouldWaitOnObject(KernelObject* object);
+	void releaseMutex(Mutex* moo);
 
 	std::optional<Handle> getPortHandle(const char* name);
 	void deleteObjectData(KernelObject& object);
@@ -106,7 +107,6 @@ private:
 	void createAddressArbiter();
 	void createEvent();
 	void createMemoryBlock();
-	void createMutex();
 	void createThread();
 	void controlMemory();
 	void duplicateHandle();
@@ -121,11 +121,12 @@ private:
 	void getSystemTick();
 	void getThreadID();
 	void getThreadPriority();
-	void releaseMutex();
 	void sendSyncRequest();
 	void setThreadPriority();
 	void signalEvent();
 	void svcCloseHandle();
+	void svcCreateMutex();
+	void svcReleaseMutex();
 	void svcSleepThread();
 	void connectToPort();
 	void outputDebugString();
diff --git a/src/core/kernel/kernel.cpp b/src/core/kernel/kernel.cpp
index 1a5184f3..93b16b4a 100644
--- a/src/core/kernel/kernel.cpp
+++ b/src/core/kernel/kernel.cpp
@@ -33,8 +33,8 @@ void Kernel::serviceSVC(u32 svc) {
 		case 0x0A: svcSleepThread(); break;
 		case 0x0B: getThreadPriority(); break;
 		case 0x0C: setThreadPriority(); break;
-		case 0x13: createMutex(); break;
-		case 0x14: releaseMutex(); break;
+		case 0x13: svcCreateMutex(); break;
+		case 0x14: svcReleaseMutex(); break;
 		case 0x17: createEvent(); break;
 		case 0x18: signalEvent(); break;
 		case 0x19: clearEvent(); break;
diff --git a/src/core/kernel/threads.cpp b/src/core/kernel/threads.cpp
index 59b3df77..b66fb902 100644
--- a/src/core/kernel/threads.cpp
+++ b/src/core/kernel/threads.cpp
@@ -171,6 +171,13 @@ Handle Kernel::makeMutex(bool locked) {
 	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.");
+	}
+}
+
 Handle Kernel::makeSemaphore(u32 initialCount, u32 maximumCount) {
 	Handle ret = makeObject(KernelObjectType::Semaphore);
 	objects[ret].data = new Semaphore(initialCount, maximumCount);
@@ -335,7 +342,7 @@ void Kernel::exitThread() {
 	switchToNextThread();
 }
 
-void Kernel::createMutex() {
+void Kernel::svcCreateMutex() {
 	bool locked = regs[1] != 0;
 	logSVC("CreateMutex (locked = %s)\n", locked ? "yes" : "no");
 
@@ -343,10 +350,24 @@ void Kernel::createMutex() {
 	regs[1] = makeMutex(locked);
 }
 
-void Kernel::releaseMutex() {
+void Kernel::svcReleaseMutex() {
 	const Handle handle = regs[0];
-
 	logSVC("ReleaseMutex (handle = %x) (STUBBED)\n", handle);
+
+	const auto object = getObject(handle, KernelObjectType::Mutex);
+	if (object == nullptr) [[unlikely]] {
+		Helpers::panic("Tried to release non-existent mutex");
+		regs[0] = SVCResult::BadHandle;
+		return;
+	}
+
+	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");
+	}
+
+	releaseMutex(moo);
 	regs[0] = SVCResult::Success;
 }