Kernel: Make spinlocks more safe

Kernel now makes sure thread is not holding any spinlocks when it tries
to lock a mutex or yield. Spinlocks are supposed to be only used for
short times without the possibility of yielding

kernel/kernel/Lock/SpinLock.cpp

@@ -0,0 +1,55 @@
+#include <kernel/Lock/SpinLock.h>
+#include <kernel/Thread.h>
+
+namespace Kernel
+{
+
+	InterruptState SpinLock::lock()
+	{
+		auto state = Processor::get_interrupt_state();
+		Processor::set_interrupt_state(InterruptState::Disabled);
+
+		auto id = Processor::current_id().as_u32();
+		ASSERT(m_locker.load(BAN::MemoryOrder::memory_order_relaxed) != id);
+
+		auto expected = PROCESSOR_NONE.as_u32();
+		while (!m_locker.compare_exchange(expected, id, BAN::MemoryOrder::memory_order_acquire))
+		{
+			Processor::pause();
+			expected = PROCESSOR_NONE.as_u32();
+		}
+
+		if (Thread::current_tid())
+			Thread::current().add_spinlock();
+
+		return state;
+	}
+
+	bool SpinLock::try_lock_interrupts_disabled()
+	{
+		ASSERT(Processor::get_interrupt_state() == InterruptState::Disabled);
+
+		auto id = Processor::current_id().as_u32();
+		ASSERT(m_locker.load(BAN::MemoryOrder::memory_order_relaxed) != id);
+
+		auto expected = PROCESSOR_NONE.as_u32();
+		if (!m_locker.compare_exchange(expected, id, BAN::MemoryOrder::memory_order_acquire))
+			return false;
+
+		if (Thread::current_tid())
+			Thread::current().add_spinlock();
+
+		return true;
+	}
+
+	void SpinLock::unlock(InterruptState state)
+	{
+		ASSERT(Processor::get_interrupt_state() == InterruptState::Disabled);
+		ASSERT(current_processor_has_lock());
+		m_locker.store(PROCESSOR_NONE.as_u32(), BAN::MemoryOrder::memory_order_release);
+		if (Thread::current_tid())
+			Thread::current().remove_spinlock();
+		Processor::set_interrupt_state(state);
+	}
+
+}

kernel/kernel/Processor.cpp

@@ -337,6 +337,8 @@ namespace Kernel
 		auto state = get_interrupt_state();
 		set_interrupt_state(InterruptState::Disabled);
 
+		ASSERT(!Thread::current().has_spinlock());
+
 		auto& processor_info = s_processors[current_id().as_u32()];
 
 		{

kernel/kernel/Thread.cpp

@@ -140,6 +140,8 @@ namespace Kernel
 
 	pid_t Thread::current_tid()
 	{
+		if (Processor::count() == 0)
+			return 0;
 		return Processor::scheduler().current_tid();
 	}