Kernel: Remove now obsolete CriticalScope

All critical scopes in kernel are now replaced by SpinLocks. This
allows proper locking in actual multiprocessing with multiple cores.

LibELF/LibELF/LoadableELF.cpp

@@ -1,5 +1,4 @@
 #include <BAN/ScopeGuard.h>
-#include <kernel/CriticalScope.h>
 #include <kernel/Memory/Heap.h>
 #include <kernel/Lock/LockGuard.h>
 #include <LibELF/LoadableELF.h>

kernel/arch/x86_64/PageTable.cpp

@@ -17,7 +17,7 @@ extern uint8_t g_userspace_end[];
 namespace Kernel
 {
 
-	SpinLock PageTable::s_fast_page_lock;
+	RecursiveSpinLock PageTable::s_fast_page_lock;
 
 	static PageTable* s_kernel = nullptr;
 	static PageTable* s_current = nullptr;
@@ -209,7 +209,8 @@ namespace Kernel
 	{
 		ASSERT(s_kernel);
 		ASSERT_NEQ(paddr, 0);
-		ASSERT(!interrupts_enabled());
+
+		SpinLockGuard _(s_fast_page_lock);
 
 		constexpr vaddr_t uc_vaddr = uncanonicalize(fast_page());
 		constexpr uint64_t pml4e = (uc_vaddr >> 39) & 0x1FF;
@@ -231,7 +232,8 @@ namespace Kernel
 	void PageTable::unmap_fast_page()
 	{
 		ASSERT(s_kernel);
-		ASSERT(!interrupts_enabled());
+
+		SpinLockGuard _(s_fast_page_lock);
 
 		constexpr vaddr_t uc_vaddr = uncanonicalize(fast_page());
 		constexpr uint64_t pml4e = (uc_vaddr >> 39) & 0x1FF;

kernel/include/kernel/APIC.h

@@ -2,6 +2,7 @@
 
 #include <BAN/Vector.h>
 #include <kernel/InterruptController.h>
+#include <kernel/Lock/SpinLock.h>
 #include <kernel/Memory/Types.h>
 
 namespace Kernel
@@ -52,6 +53,7 @@ namespace Kernel
 		};
 
 	private:
+		SpinLock				m_lock;
 		BAN::Vector<Processor>	m_processors;
 		Kernel::paddr_t			m_local_apic_paddr = 0;
 		Kernel::vaddr_t			m_local_apic_vaddr = 0;

kernel/include/kernel/CriticalScope.h

@@ -1,30 +0,0 @@
-#pragma once
-
-#include <BAN/NoCopyMove.h>
-
-#include <stddef.h>
-
-namespace Kernel
-{
-
-	class CriticalScope
-	{
-		BAN_NON_COPYABLE(CriticalScope);
-		BAN_NON_MOVABLE(CriticalScope);
-
-	public:
-		CriticalScope()
-		{
-			asm volatile("pushf; cli; pop %0" : "=r"(m_flags) :: "memory");
-		}
-
-		~CriticalScope()
-		{
-			asm volatile("push %0; popf" :: "rm"(m_flags) : "memory", "cc");
-		}
-
-	private:
-		size_t m_flags;
-	};
-
-}

kernel/include/kernel/Input/KeyboardLayout.h

@@ -3,6 +3,7 @@
 #include <BAN/Array.h>
 #include <BAN/UniqPtr.h>
 #include <kernel/Input/KeyEvent.h>
+#include <kernel/Lock/SpinLock.h>
 
 namespace Kernel::Input
 {
@@ -23,6 +24,7 @@ namespace Kernel::Input
 		BAN::Array<Key, 0xFF> m_keycode_to_key_normal;
 		BAN::Array<Key, 0xFF> m_keycode_to_key_shift;
 		BAN::Array<Key, 0xFF> m_keycode_to_key_altgr;
+		SpinLock m_lock;
 
 		friend class BAN::UniqPtr<KeyboardLayout>;
 	};

kernel/include/kernel/Input/PS2/Controller.h

@@ -64,6 +64,7 @@ namespace Kernel::Input
 
 		BAN::CircularQueue<Command, 128> m_command_queue;
 		uint64_t m_command_send_time { 0 };
+		SpinLock m_command_lock;
 	};
 
 }

kernel/include/kernel/Input/PS2/Keyboard.h

@@ -41,6 +41,7 @@ namespace Kernel::Input
 		uint16_t m_modifiers { 0 };
 
 		BAN::CircularQueue<KeyEvent, 50> m_event_queue;
+		SpinLock m_event_lock;
 
 		PS2Keymap m_keymap;
 

kernel/include/kernel/Input/PS2/Mouse.h

@@ -37,6 +37,7 @@ namespace Kernel::Input
 		uint8_t m_button_mask	{ 0x00 };
 
 		BAN::CircularQueue<MouseEvent, 128> m_event_queue;
+		SpinLock m_event_lock;
 
 		Semaphore m_semaphore;
 

kernel/include/kernel/InterruptController.h

@@ -5,9 +5,6 @@
 
 #include <stdint.h>
 
-#define DISABLE_INTERRUPTS() asm volatile("cli")
-#define ENABLE_INTERRUPTS() asm volatile("sti")
-
 namespace Kernel
 {
 
@@ -51,11 +48,4 @@ namespace Kernel
 		bool m_using_apic { false };
 	};
 
-	inline bool interrupts_enabled()
-	{
-		uintptr_t flags;
-		asm volatile("pushf; pop %0" : "=r"(flags) :: "memory");
-		return flags & (1 << 9);
-	}
-
 }

kernel/include/kernel/Interrupts.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include <kernel/Arch.h>
+
+namespace Kernel
+{
+
+	enum class InterruptState
+	{
+		Disabled,
+		Enabled,
+	};
+
+#if ARCH(x86_64) || ARCH(i386)
+
+	inline void set_interrupt_state(InterruptState state)
+	{
+		if (state == InterruptState::Enabled)
+			asm volatile("sti");
+		else
+			asm volatile("cli");
+	}
+
+	inline InterruptState get_interrupt_state()
+	{
+		uintptr_t flags;
+		asm volatile("pushf; pop %0" : "=rm"(flags));
+		if (flags & (1 << 9))
+			return InterruptState::Enabled;
+		return InterruptState::Disabled;
+	}
+
+#else
+#error "Unknown architecure"
+#endif
+
+}

kernel/include/kernel/Lock/SpinLock.h

@@ -2,14 +2,13 @@
 
 #include <BAN/Atomic.h>
 #include <BAN/NoCopyMove.h>
+#include <kernel/Interrupts.h>
 
 #include <sys/types.h>
 
 namespace Kernel
 {
 
-	using InterruptState = bool;
-
 	class SpinLock
 	{
 		BAN_NON_COPYABLE(SpinLock);
@@ -41,6 +40,37 @@ namespace Kernel
 		uint32_t m_lock_depth { 0 };
 	};
 
+	class SpinLockUnsafe
+	{
+		BAN_NON_COPYABLE(SpinLockUnsafe);
+		BAN_NON_MOVABLE(SpinLockUnsafe);
+
+	public:
+		SpinLockUnsafe() = default;
+
+		InterruptState lock()
+		{
+			auto state = get_interrupt_state();
+			set_interrupt_state(InterruptState::Disabled);
+
+			while (!m_locked.compare_exchange(false, true))
+				__builtin_ia32_pause();
+
+			return state;
+		}
+
+		void unlock(InterruptState state)
+		{
+			m_locked.store(false);
+			set_interrupt_state(state);
+		}
+
+		bool is_locked() const { return m_locked; }
+
+	private:
+		BAN::Atomic<bool> m_locked;
+	};
+
 	template<typename Lock>
 	class SpinLockGuard
 	{

kernel/include/kernel/Memory/PageTable.h

@@ -2,7 +2,6 @@
 
 #include <BAN/Errors.h>
 #include <BAN/Traits.h>
-#include <kernel/CriticalScope.h>
 #include <kernel/Lock/SpinLock.h>
 #include <kernel/Memory/Types.h>
 
@@ -130,7 +129,7 @@ namespace Kernel
 	private:
 		paddr_t						m_highest_paging_struct { 0 };
 		mutable RecursiveSpinLock	m_lock;
-		static SpinLock				s_fast_page_lock;
+		static RecursiveSpinLock	s_fast_page_lock;
 	};
 
 	static constexpr size_t range_page_count(vaddr_t start, size_t bytes)

kernel/include/kernel/Networking/ARPTable.h

@@ -52,6 +52,7 @@ namespace Kernel
 
 	private:
 		SpinLock m_table_lock;
+		SpinLock m_pending_lock;
 
 		BAN::HashMap<BAN::IPv4Address, BAN::MACAddress> m_arp_table;
 

kernel/include/kernel/Networking/E1000/E1000.h

@@ -71,6 +71,7 @@ namespace Kernel
 		BAN::UniqPtr<DMARegion>	m_tx_buffer_region;
 		BAN::UniqPtr<DMARegion>	m_rx_descriptor_region;
 		BAN::UniqPtr<DMARegion>	m_tx_descriptor_region;
+		SpinLock m_lock;
 
 		BAN::MACAddress	m_mac_address {};
 		bool			m_link_up { false };

kernel/include/kernel/Networking/IPv4Layer.h

@@ -76,6 +76,7 @@ namespace Kernel
 		BAN::UniqPtr<VirtualRange>					m_pending_packet_buffer;
 		BAN::CircularQueue<PendingIPv4Packet, 128>	m_pending_packets;
 		Semaphore									m_pending_semaphore;
+		SpinLock									m_pending_lock;
 		size_t										m_pending_total_size { 0 };
 
 		BAN::HashMap<int, BAN::WeakPtr<NetworkSocket>>	m_bound_sockets;

kernel/include/kernel/PIC.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <kernel/InterruptController.h>
+#include <kernel/Lock/SpinLock.h>
 
 namespace Kernel
 {
@@ -20,8 +21,12 @@ namespace Kernel
 
 	private:
 		static PIC* create();
-		friend class InterruptController;
+
+	private:
+		SpinLock m_lock;
 		uint16_t m_reserved_irqs { 0 };
+
+		friend class InterruptController;
 	};
 
 }

kernel/include/kernel/Process.h

@@ -224,8 +224,8 @@ namespace Kernel
 		BAN::String m_working_directory;
 		BAN::Vector<Thread*> m_threads;
 
-		vaddr_t m_signal_handlers[_SIGMAX + 1] { };
-		uint64_t m_signal_pending_mask { 0 };
+		BAN::Atomic<vaddr_t> m_signal_handlers[_SIGMAX + 1] { };
+		BAN::Atomic<uint64_t> m_signal_pending_mask { 0 };
 
 		BAN::Vector<BAN::String> m_cmdline;
 		BAN::Vector<BAN::String> m_environ;

kernel/include/kernel/Scheduler.h

@@ -30,9 +30,12 @@ namespace Kernel
 		static pid_t current_tid();
 
 		[[noreturn]] void execute_current_thread();
-		[[noreturn]] void _execute_current_thread();
+		[[noreturn]] void execute_current_thread_locked();
 		[[noreturn]] void delete_current_process_and_thread();
 
+		// This is no return if called on current thread
+		void terminate_thread(Thread*);
+
 	private:
 		Scheduler() = default;
 
@@ -43,6 +46,8 @@ namespace Kernel
 		void remove_and_advance_current_thread();
 		void advance_current_thread();
 
+		[[noreturn]] void execute_current_thread_stack_loaded();
+
 		BAN::ErrorOr<void> add_thread(Thread*);
 
 	private:
@@ -57,6 +62,8 @@ namespace Kernel
 			Semaphore*	semaphore;
 		};
 
+		SpinLockUnsafe m_lock;
+
 		Thread* m_idle_thread { nullptr };
 		BAN::LinkedList<SchedulerThread> m_active_threads;
 		BAN::LinkedList<SchedulerThread> m_sleeping_threads;

kernel/include/kernel/Terminal/Serial.h

@@ -62,6 +62,7 @@ namespace Kernel
 		BAN::String m_name;
 		Serial m_serial;
 		BAN::CircularQueue<uint8_t, 128> m_input;
+		SpinLock m_input_lock;
 
 	public:
 		virtual dev_t rdev() const override { return m_rdev; }

kernel/include/kernel/Thread.h

@@ -65,8 +65,6 @@ namespace Kernel
 		uintptr_t rip() const { return m_rip; }
 
 		void set_started() { ASSERT(m_state == State::NotStarted); m_state = State::Executing; }
-		// Thread will no longer execute. If called on current thread, does not return
-		void terminate();
 		State state() const { return m_state; }
 
 		vaddr_t stack_base() const { return m_stack->vaddr(); }
@@ -118,6 +116,7 @@ namespace Kernel
 
 		uint64_t					m_signal_pending_mask	{ 0 };
 		uint64_t					m_signal_block_mask		{ 0 };
+		SpinLock					m_signal_lock;
 		static_assert(_SIGMAX < 64);
 
 #if __enable_sse

kernel/include/kernel/Timer/HPET.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <kernel/InterruptController.h>
+#include <kernel/Lock/SpinLock.h>
 #include <kernel/Timer/Timer.h>
 
 namespace Kernel
@@ -30,6 +31,8 @@ namespace Kernel
 		uint64_t read_main_counter() const;
 
 	private:
+		mutable SpinLock m_lock;
+
 		bool m_is_64bit { false };
 
 		uint64_t m_last_ticks	{ 0 };

kernel/kernel/APIC.cpp

@@ -223,7 +223,7 @@ namespace Kernel
 
 	void APIC::enable_irq(uint8_t irq)
 	{
-		CriticalScope _;
+		SpinLockGuard _(m_lock);
 
 		uint32_t gsi = m_irq_overrides[irq];
 
@@ -268,7 +268,7 @@ namespace Kernel
 
 	BAN::ErrorOr<void> APIC::reserve_irq(uint8_t irq)
 	{
-		CriticalScope _;
+		SpinLockGuard _(m_lock);
 
 		uint32_t gsi = m_irq_overrides[irq];
 
@@ -301,7 +301,7 @@ namespace Kernel
 
 	BAN::Optional<uint8_t> APIC::get_free_irq()
 	{
-		CriticalScope _;
+		SpinLockGuard _(m_lock);
 		for (int irq = 0; irq <= 0xFF; irq++)
 		{
 			uint32_t gsi = m_irq_overrides[irq];

kernel/kernel/Input/KeyboardLayout.cpp

@@ -1,5 +1,4 @@
 #include <BAN/HashMap.h>
-#include <kernel/CriticalScope.h>
 #include <kernel/FS/VirtualFileSystem.h>
 #include <kernel/Input/KeyboardLayout.h>
 
@@ -74,6 +73,7 @@ namespace Kernel::Input
 
 	Key KeyboardLayout::get_key_from_event(KeyEvent event)
 	{
+		SpinLockGuard _(m_lock);
 		if (event.shift())
 			return m_keycode_to_key_shift[event.keycode];
 		if (event.ralt())
@@ -256,7 +256,7 @@ namespace Kernel::Input
 			}
 		}
 
-		CriticalScope _;
+		SpinLockGuard _(m_lock);
 
 		for (size_t i = 0; i < new_layout->m_keycode_to_key_normal.size(); i++)
 			if (new_layout->m_keycode_to_key_normal[i] != Key::None)

kernel/kernel/Input/PS2/Controller.cpp

@@ -6,7 +6,6 @@
 #include <kernel/Input/PS2/Controller.h>
 #include <kernel/Input/PS2/Keyboard.h>
 #include <kernel/Input/PS2/Mouse.h>
-#include <kernel/InterruptController.h>
 #include <kernel/IO.h>
 #include <kernel/Timer/Timer.h>
 
@@ -21,7 +20,6 @@ namespace Kernel::Input
 
 	BAN::ErrorOr<void> PS2Controller::send_byte(uint16_t port, uint8_t byte)
 	{
-		ASSERT(interrupts_enabled());
 		LockGuard _(m_mutex);
 		uint64_t timeout = SystemTimer::get().ms_since_boot() + s_ps2_timeout_ms;
 		while (SystemTimer::get().ms_since_boot() < timeout)
@@ -36,7 +34,6 @@ namespace Kernel::Input
 
 	BAN::ErrorOr<uint8_t> PS2Controller::read_byte()
 	{
-		ASSERT(interrupts_enabled());
 		LockGuard _(m_mutex);
 		uint64_t timeout = SystemTimer::get().ms_since_boot() + s_ps2_timeout_ms;
 		while (SystemTimer::get().ms_since_boot() < timeout)
@@ -101,8 +98,7 @@ namespace Kernel::Input
 
 	bool PS2Controller::append_command_queue(PS2Device* device, uint8_t command, uint8_t response_size)
 	{
-		// NOTE: command queue push/pop must be done without interrupts
-		CriticalScope _;
+		SpinLockGuard _(m_command_lock);
 		if (m_command_queue.size() + 1 >= m_command_queue.capacity())
 		{
 			dprintln("PS/2 command queue full");
@@ -121,8 +117,7 @@ namespace Kernel::Input
 
 	bool PS2Controller::append_command_queue(PS2Device* device, uint8_t command, uint8_t data, uint8_t response_size)
 	{
-		// NOTE: command queue push/pop must be done without interrupts
-		CriticalScope _;
+		SpinLockGuard _(m_command_lock);
 		if (m_command_queue.size() + 1 >= m_command_queue.capacity())
 		{
 			dprintln("PS/2 command queue full");
@@ -141,35 +136,38 @@ namespace Kernel::Input
 
 	void PS2Controller::update_command_queue()
 	{
-		ASSERT(interrupts_enabled());
+		Command command_copy;
 
-		if (m_command_queue.empty())
-			return;
-		auto& command = m_command_queue.front();
-		if (command.state == Command::State::WaitingResponse || command.state == Command::State::WaitingAck)
 		{
-			if (SystemTimer::get().ms_since_boot() >= m_command_send_time + s_ps2_timeout_ms)
+			SpinLockGuard _(m_command_lock);
+
+			if (m_command_queue.empty())
+				return;
+			auto& command = m_command_queue.front();
+			if (command.state == Command::State::WaitingResponse || command.state == Command::State::WaitingAck)
 			{
-				dwarnln_if(DEBUG_PS2, "Command timedout");
-				m_devices[command.device_index]->command_timedout(command.out_data, command.out_count);
-				m_command_queue.pop();
+				if (SystemTimer::get().ms_since_boot() >= m_command_send_time + s_ps2_timeout_ms)
+				{
+					dwarnln_if(DEBUG_PS2, "Command timedout");
+					m_devices[command.device_index]->command_timedout(command.out_data, command.out_count);
+					m_command_queue.pop();
+				}
+				return;
 			}
-			return;
+			ASSERT(command.send_index < command.out_count);
+			command.state = Command::State::WaitingAck;
+
+			command_copy = command;
 		}
-		ASSERT(command.send_index < command.out_count);
-		command.state = Command::State::WaitingAck;
+
 		m_command_send_time = SystemTimer::get().ms_since_boot();
-		if (auto ret = device_send_byte(command.device_index, command.out_data[command.send_index]); ret.is_error())
-		{
-			command.state = Command::State::Sending;
+		if (auto ret = device_send_byte(command_copy.device_index, command_copy.out_data[command_copy.send_index]); ret.is_error())
 			dwarnln_if(DEBUG_PS2, "PS/2 send command byte: {}", ret.error());
-		}
 	}
 
 	bool PS2Controller::handle_command_byte(PS2Device* device, uint8_t byte)
 	{
-		// NOTE: command queue push/pop must be done without interrupts
-		ASSERT(!interrupts_enabled());
+		SpinLockGuard _(m_command_lock);
 
 		if (m_command_queue.empty())
 			return false;

kernel/kernel/Input/PS2/Keyboard.cpp

@@ -1,5 +1,4 @@
 #include <BAN/ScopeGuard.h>
-#include <kernel/CriticalScope.h>
 #include <kernel/FS/DevFS/FileSystem.h>
 #include <kernel/Input/KeyboardLayout.h>
 #include <kernel/Input/PS2/Config.h>
@@ -165,6 +164,8 @@ namespace Kernel::Input
 		event.modifier = m_modifiers | (released ? 0 : KeyEvent::Modifier::Pressed);
 		event.keycode = keycode.value();
 
+		SpinLockGuard _(m_event_lock);
+
 		if (m_event_queue.full())
 		{
 			dwarnln("PS/2 event queue full");
@@ -192,20 +193,20 @@ namespace Kernel::Input
 		if (buffer.size() < sizeof(KeyEvent))
 			return BAN::Error::from_errno(ENOBUFS);
 
-		while (true)
+		auto state = m_event_lock.lock();
+		while (m_event_queue.empty())
 		{
-			if (m_event_queue.empty())
-				TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
-
-			CriticalScope _;
-			if (m_event_queue.empty())
-				continue;
-
-			buffer.as<KeyEvent>() = m_event_queue.front();
-			m_event_queue.pop();
-
-			return sizeof(KeyEvent);
+			m_event_lock.unlock(state);
+			TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
+			state = m_event_lock.lock();
 		}
+
+		buffer.as<KeyEvent>() = m_event_queue.front();
+		m_event_queue.pop();
+
+		m_event_lock.unlock(state);
+
+		return sizeof(KeyEvent);
 	}
 
 }

kernel/kernel/Input/PS2/Mouse.cpp

@@ -1,5 +1,4 @@
 #include <BAN/ScopeGuard.h>
-#include <kernel/CriticalScope.h>
 #include <kernel/FS/DevFS/FileSystem.h>
 #include <kernel/Input/PS2/Config.h>
 #include <kernel/Input/PS2/Mouse.h>
@@ -158,6 +157,8 @@ namespace Kernel::Input
 			event.scroll_event.scroll = rel_z;
 		}
 
+		SpinLockGuard _(m_event_lock);
+
 		for (int i = 0; i < event_count; i++)
 		{
 			if (m_event_queue.full())
@@ -176,20 +177,20 @@ namespace Kernel::Input
 		if (buffer.size() < sizeof(MouseEvent))
 			return BAN::Error::from_errno(ENOBUFS);
 
-		while (true)
+		auto state = m_event_lock.lock();
+		while (m_event_queue.empty())
 		{
-			if (m_event_queue.empty())
-				TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
-
-			CriticalScope _;
-			if (m_event_queue.empty())
-				continue;
-
-			buffer.as<MouseEvent>() = m_event_queue.front();
-			m_event_queue.pop();
-
-			return sizeof(MouseEvent);
+			m_event_lock.unlock(state);
+			TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
+			state = m_event_lock.lock();
 		}
+
+		buffer.as<MouseEvent>() = m_event_queue.front();
+		m_event_queue.pop();
+
+		m_event_lock.unlock(state);
+
+		return sizeof(MouseEvent);
 	}
 
 }

kernel/kernel/Lock/SpinLock.cpp

@@ -12,8 +12,8 @@ namespace Kernel
 		auto tid = Scheduler::current_tid();
 		ASSERT_NEQ(m_locker.load(), tid);
 
-		InterruptState state = interrupts_enabled();
-		DISABLE_INTERRUPTS();
+		auto state = get_interrupt_state();
+		set_interrupt_state(InterruptState::Disabled);
 
 		if (!m_locker.compare_exchange(-1, tid))
 			ASSERT_NOT_REACHED();
@@ -25,16 +25,15 @@ namespace Kernel
 	{
 		ASSERT_EQ(m_locker.load(), Scheduler::current_tid());
 		m_locker.store(-1);
-		if (state)
-			ENABLE_INTERRUPTS();
+		set_interrupt_state(state);
 	}
 
 	InterruptState RecursiveSpinLock::lock()
 	{
 		auto tid = Scheduler::current_tid();
 
-		InterruptState state = interrupts_enabled();
-		DISABLE_INTERRUPTS();
+		auto state = get_interrupt_state();
+		set_interrupt_state(InterruptState::Disabled);
 
 		if (tid == m_locker)
 			ASSERT_GT(m_lock_depth, 0);
@@ -57,8 +56,7 @@ namespace Kernel
 		ASSERT_GT(m_lock_depth, 0);
 		if (--m_lock_depth == 0)
 			m_locker = -1;
-		if (state)
-			ENABLE_INTERRUPTS();
+		set_interrupt_state(state);
 	}
 
 }

kernel/kernel/Memory/FileBackedRegion.cpp

@@ -1,4 +1,3 @@
-#include <kernel/CriticalScope.h>
 #include <kernel/Lock/LockGuard.h>
 #include <kernel/Memory/FileBackedRegion.h>
 #include <kernel/Memory/Heap.h>
@@ -83,12 +82,9 @@ namespace Kernel
 		if (pages[page_index] == 0)
 			return;
 
-		{
-			CriticalScope _;
-			PageTable::with_fast_page(pages[page_index], [&] {
-				memcpy(page_buffer, PageTable::fast_page_as_ptr(), PAGE_SIZE);
-			});
-		}
+		PageTable::with_fast_page(pages[page_index], [&] {
+			memcpy(page_buffer, PageTable::fast_page_as_ptr(), PAGE_SIZE);
+		});
 
 		if (auto ret = inode->write(page_index * PAGE_SIZE, BAN::ConstByteSpan::from(page_buffer)); ret.is_error())
 			dwarnln("{}", ret.error());

kernel/kernel/Memory/MemoryBackedRegion.cpp

@@ -1,4 +1,3 @@
-#include <kernel/CriticalScope.h>
 #include <kernel/Lock/LockGuard.h>
 #include <kernel/Memory/Heap.h>
 #include <kernel/Memory/MemoryBackedRegion.h>

kernel/kernel/Memory/VirtualRange.cpp

@@ -1,4 +1,3 @@
-#include <kernel/CriticalScope.h>
 #include <kernel/Lock/LockGuard.h>
 #include <kernel/Memory/Heap.h>
 #include <kernel/Memory/VirtualRange.h>

kernel/kernel/Memory/kmalloc.cpp

@@ -1,5 +1,4 @@
 #include <BAN/Errors.h>
-#include <kernel/CriticalScope.h>
 #include <kernel/kprint.h>
 #include <kernel/Memory/kmalloc.h>
 
@@ -81,6 +80,8 @@ struct kmalloc_info
 };
 static kmalloc_info s_kmalloc_info;
 
+static Kernel::SpinLock s_kmalloc_lock;
+
 template<size_t SIZE>
 struct kmalloc_fixed_node
 {
@@ -144,6 +145,8 @@ void kmalloc_initialize()
 
 void kmalloc_dump_info()
 {
+	Kernel::SpinLockGuard _(s_kmalloc_lock);
+
 	kprintln("kmalloc:               0x{8H}->0x{8H}", s_kmalloc_info.base, s_kmalloc_info.end);
 	kprintln("  used: 0x{8H}", s_kmalloc_info.used);
 	kprintln("  free: 0x{8H}", s_kmalloc_info.free);
@@ -155,6 +158,7 @@ void kmalloc_dump_info()
 
 static bool is_corrupted()
 {
+	Kernel::SpinLockGuard _(s_kmalloc_lock);
 	auto& info = s_kmalloc_info;
 	auto* temp = info.first();
 	for (; temp->end() <= info.end; temp = temp->after());
@@ -163,6 +167,8 @@ static bool is_corrupted()
 
 [[maybe_unused]] static void debug_dump()
 {
+	Kernel::SpinLockGuard _(s_kmalloc_lock);
+
 	auto& info = s_kmalloc_info;
 
 	uint32_t used = 0;
@@ -181,6 +187,8 @@ static bool is_corrupted()
 
 static void* kmalloc_fixed()
 {
+	Kernel::SpinLockGuard _(s_kmalloc_lock);
+
 	auto& info = s_kmalloc_fixed_info;
 
 	if (!info.free_list_head)
@@ -223,6 +231,8 @@ static void* kmalloc_impl(size_t size, size_t align)
 	ASSERT(align % s_kmalloc_min_align == 0);
 	ASSERT(size % s_kmalloc_min_align == 0);
 
+	Kernel::SpinLockGuard _(s_kmalloc_lock);
+
 	auto& info = s_kmalloc_info;
 
 	for (auto* node = info.first(); node->end() <= info.end; node = node->after())
@@ -304,8 +314,6 @@ void* kmalloc(size_t size, size_t align, bool force_identity_map)
 		align = s_kmalloc_min_align;
 	ASSERT(align <= PAGE_SIZE);
 
-	Kernel::CriticalScope critical;
-
 	if (size == 0 || size >= info.size)
 		goto no_memory;
 
@@ -338,7 +346,7 @@ void kfree(void* address)
 	uintptr_t address_uint = (uintptr_t)address;
 	ASSERT(address_uint % s_kmalloc_min_align == 0);
 
-	Kernel::CriticalScope critical;
+	Kernel::SpinLockGuard _(s_kmalloc_lock);
 
 	if (s_kmalloc_fixed_info.base <= address_uint && address_uint < s_kmalloc_fixed_info.end)
 	{

kernel/kernel/Networking/ARPTable.cpp

@@ -145,24 +145,22 @@ namespace Kernel
 	{
 		for (;;)
 		{
-			BAN::Optional<PendingArpPacket> pending;
-
-			{
-				CriticalScope _;
-				if (!m_pending_packets.empty())
+			PendingArpPacket pending = ({
+				auto state = m_pending_lock.lock();
+				while (m_pending_packets.empty())
 				{
-					pending = m_pending_packets.front();
-					m_pending_packets.pop();
+					m_pending_lock.unlock(state);
+					m_pending_semaphore.block_indefinite();
+					state = m_pending_lock.lock();
 				}
-			}
+				auto packet = m_pending_packets.front();
+				m_pending_packets.pop();
+				m_pending_lock.unlock(state);
 
-			if (!pending.has_value())
-			{
-				m_pending_semaphore.block_indefinite();
-				continue;
-			}
+				packet;
+			});
 
-			if (auto ret = handle_arp_packet(pending->interface, pending->packet); ret.is_error())
+			if (auto ret = handle_arp_packet(pending.interface, pending.packet); ret.is_error())
 				dwarnln("{}", ret.error());
 		}
 	}
@@ -171,6 +169,8 @@ namespace Kernel
 	{
 		auto& arp_packet = buffer.as<const ARPPacket>();
 
+		SpinLockGuard _(m_pending_lock);
+
 		if (m_pending_packets.full())
 		{
 			dprintln("arp packet queue full");

kernel/kernel/Networking/E1000/E1000.cpp

@@ -261,7 +261,7 @@ namespace Kernel
 	{
 		ASSERT_LTE(buffer.size() + sizeof(EthernetHeader), E1000_TX_BUFFER_SIZE);
 
-		CriticalScope _;
+		SpinLockGuard _(m_lock);
 
 		size_t tx_current = read32(REG_TDT) % E1000_TX_DESCRIPTOR_COUNT;
 
@@ -291,6 +291,8 @@ namespace Kernel
 		if (read32(REG_ICR) & ICR_RxQ0)
 			return;
 
+		SpinLockGuard _(m_lock);
+
 		for (;;) {
 			uint32_t rx_current = (read32(REG_RDT0) + 1) % E1000_RX_DESCRIPTOR_COUNT;
 

kernel/kernel/Networking/IPv4Layer.cpp

@@ -287,30 +287,28 @@ namespace Kernel
 	{
 		for (;;)
 		{
-			BAN::Optional<PendingIPv4Packet> pending;
-
-			{
-				CriticalScope _;
-				if (!m_pending_packets.empty())
+			PendingIPv4Packet pending = ({
+				auto state = m_pending_lock.lock();
+				while (m_pending_packets.empty())
 				{
-					pending = m_pending_packets.front();
-					m_pending_packets.pop();
+					m_pending_lock.unlock(state);
+					m_pending_semaphore.block_indefinite();
+					state = m_pending_lock.lock();
 				}
-			}
+				auto packet = m_pending_packets.front();
+				m_pending_packets.pop();
+				m_pending_lock.unlock(state);
 
-			if (!pending.has_value())
-			{
-				m_pending_semaphore.block_indefinite();
-				continue;
-			}
+				packet;
+			});
 
 			uint8_t* buffer_start = reinterpret_cast<uint8_t*>(m_pending_packet_buffer->vaddr());
 			const size_t ipv4_packet_size = reinterpret_cast<const IPv4Header*>(buffer_start)->total_length;
 
-			if (auto ret = handle_ipv4_packet(pending->interface, BAN::ByteSpan(buffer_start, ipv4_packet_size)); ret.is_error())
+			if (auto ret = handle_ipv4_packet(pending.interface, BAN::ByteSpan(buffer_start, ipv4_packet_size)); ret.is_error())
 				dwarnln("{}", ret.error());
 
-			CriticalScope _;
+			SpinLockGuard _(m_pending_lock);
 			m_pending_total_size -= ipv4_packet_size;
 			if (m_pending_total_size)
 				memmove(buffer_start, buffer_start + ipv4_packet_size, m_pending_total_size);
@@ -319,6 +317,8 @@ namespace Kernel
 
 	void IPv4Layer::add_ipv4_packet(NetworkInterface& interface, BAN::ConstByteSpan buffer)
 	{
+		SpinLockGuard _(m_pending_lock);
+
 		if (m_pending_packets.full())
 		{
 			dwarnln("IPv4 packet queue full");

kernel/kernel/PIC.cpp

@@ -1,4 +1,3 @@
-#include <kernel/CriticalScope.h>
 #include <kernel/IDT.h>
 #include <kernel/IO.h>
 #include <kernel/PIC.h>
@@ -71,7 +70,7 @@ namespace Kernel
 
 	void PIC::eoi(uint8_t irq)
 	{
-		ASSERT(!interrupts_enabled());
+		SpinLockGuard _(m_lock);
 		if (irq >= 8)
 			IO::outb(PIC2_CMD, PIC_EOI);
 		IO::outb(PIC1_CMD, PIC_EOI);
@@ -79,7 +78,7 @@ namespace Kernel
 
 	void PIC::enable_irq(uint8_t irq)
 	{
-		CriticalScope _;
+		SpinLockGuard _(m_lock);
 		ASSERT(irq < 16);
 		ASSERT(m_reserved_irqs & (1 << irq));
 
@@ -99,7 +98,7 @@ namespace Kernel
 			dwarnln("PIC only supports 16 irqs");
 			return BAN::Error::from_errno(EFAULT);
 		}
-		CriticalScope _;
+		SpinLockGuard _(m_lock);
 		if (m_reserved_irqs & (1 << irq))
 		{
 			dwarnln("irq {} is already reserved", irq);
@@ -111,7 +110,7 @@ namespace Kernel
 
 	BAN::Optional<uint8_t> PIC::get_free_irq()
 	{
-		CriticalScope _;
+		SpinLockGuard _(m_lock);
 		for (int irq = 0; irq < 16; irq++)
 		{
 			if (m_reserved_irqs & (1 << irq))
@@ -119,12 +118,12 @@ namespace Kernel
 			m_reserved_irqs |= 1 << irq;
 			return irq;
 		}
-
 		return {};
 	}
 
 	bool PIC::is_in_service(uint8_t irq)
 	{
+		SpinLockGuard _(m_lock);
 		uint16_t port = PIC1_CMD;
 		if (irq >= 8)
 		{

kernel/kernel/Process.cpp

@@ -1,6 +1,5 @@
 #include <BAN/ScopeGuard.h>
 #include <BAN/StringView.h>
-#include <kernel/CriticalScope.h>
 #include <kernel/FS/DevFS/FileSystem.h>
 #include <kernel/FS/ProcFS/FileSystem.h>
 #include <kernel/FS/VirtualFileSystem.h>
@@ -62,18 +61,13 @@ namespace Kernel
 
 	Process* Process::create_process(const Credentials& credentials, pid_t parent, pid_t sid, pid_t pgrp)
 	{
-		static pid_t s_next_id = 1;
+		static BAN::Atomic<pid_t> s_next_id = 1;
 
-		pid_t pid;
+		pid_t pid = s_next_id++;
+		if (sid == 0 && pgrp == 0)
 		{
-			CriticalScope _;
-			pid = s_next_id;
-			if (sid == 0 && pgrp == 0)
-			{
-				sid = s_next_id;
-				pgrp = s_next_id;
-			}
-			s_next_id++;
+			sid = pid;
+			pgrp = pid;
 		}
 
 		ASSERT(sid > 0);
@@ -226,7 +220,7 @@ namespace Kernel
 
 	void Process::on_thread_exit(Thread& thread)
 	{
-		ASSERT(!interrupts_enabled());
+		ASSERT(get_interrupt_state() == InterruptState::Disabled);
 
 		ASSERT(m_threads.size() > 0);
 
@@ -236,7 +230,8 @@ namespace Kernel
 			m_threads.clear();
 
 			thread.setup_process_cleanup();
-			Scheduler::get().execute_current_thread();
+			// NOTE: This function is only called from scheduler when it is already locked
+			Scheduler::get().execute_current_thread_locked();
 			ASSERT_NOT_REACHED();
 		}
 
@@ -258,9 +253,9 @@ namespace Kernel
 		m_exit_status.exit_code = __WGENEXITCODE(status, signal);
 		for (auto* thread : m_threads)
 			if (thread != &Thread::current())
-				thread->terminate();
+				Scheduler::get().terminate_thread(thread);
 		if (this == &Process::current())
-			Thread::current().terminate();
+			Scheduler::get().terminate_thread(&Thread::current());
 	}
 
 	size_t Process::proc_meminfo(off_t offset, BAN::ByteSpan buffer) const
@@ -336,8 +331,8 @@ namespace Kernel
 
 	BAN::ErrorOr<long> Process::sys_exit(int status)
 	{
+		ASSERT(this == &Process::current());
 		exit(status, 0);
-		Thread::current().terminate();
 		ASSERT_NOT_REACHED();
 	}
 
@@ -1484,7 +1479,6 @@ namespace Kernel
 			TRY(validate_pointer_access((void*)handler, sizeof(handler)));
 		}
 
-		CriticalScope _;
 		m_signal_handlers[signal] = (vaddr_t)handler;
 		return 0;
 	}
@@ -1496,10 +1490,9 @@ namespace Kernel
 		if (signal != 0 && (signal < _SIGMIN || signal > _SIGMAX))
 			return BAN::Error::from_errno(EINVAL);
 
-		if (pid == Process::current().pid())
+		if (pid == m_pid)
 		{
-			CriticalScope _;
-			Process::current().m_signal_pending_mask |= 1 << signal;
+			m_signal_pending_mask |= 1 << signal;
 			return 0;
 		}
 
@@ -1512,9 +1505,8 @@ namespace Kernel
 					found = true;
 					if (signal)
 					{
-						CriticalScope _;
 						process.m_signal_pending_mask |= 1 << signal;
-						// FIXME: This is super hacky
+						// FIXME: This feels hacky
 						Scheduler::get().unblock_thread(process.m_threads.front()->tid());
 					}
 					return (pid > 0) ? BAN::Iteration::Break : BAN::Iteration::Continue;

kernel/kernel/Scheduler.cpp

@@ -1,6 +1,5 @@
 #include <kernel/Arch.h>
 #include <kernel/Attributes.h>
-#include <kernel/CriticalScope.h>
 #include <kernel/GDT.h>
 #include <kernel/InterruptController.h>
 #include <kernel/Process.h>
@@ -8,15 +7,6 @@
 #include <kernel/Timer/Timer.h>
 
 #define SCHEDULER_VERIFY_STACK 1
-#define SCHEDULER_VERIFY_INTERRUPT_STATE 1
-
-#if SCHEDULER_VERIFY_INTERRUPT_STATE
-	#define VERIFY_STI() ASSERT(interrupts_enabled())
-	#define VERIFY_CLI() ASSERT(!interrupts_enabled())
-#else
-	#define VERIFY_STI()
-	#define VERIFY_CLI()
-#endif
 
 namespace Kernel
 {
@@ -50,10 +40,11 @@ namespace Kernel
 
 	void Scheduler::start()
 	{
-		VERIFY_CLI();
+		ASSERT(get_interrupt_state() == InterruptState::Disabled);
+		m_lock.lock();
 		ASSERT(!m_active_threads.empty());
 		m_current_thread = m_active_threads.begin();
-		execute_current_thread();
+		execute_current_thread_locked();
 		ASSERT_NOT_REACHED();
 	}
 
@@ -71,48 +62,40 @@ namespace Kernel
 
 	void Scheduler::timer_reschedule()
 	{
-		VERIFY_CLI();
-
+		auto state = m_lock.lock();
 		wake_threads();
-
 		if (save_current_thread())
-			return;
+			return m_lock.unlock(state);
 		advance_current_thread();
-		execute_current_thread();
+		execute_current_thread_locked();
 		ASSERT_NOT_REACHED();
 	}
 
 	void Scheduler::reschedule()
 	{
-		DISABLE_INTERRUPTS();
-
+		auto state = m_lock.lock();
 		if (save_current_thread())
-		{
-			ENABLE_INTERRUPTS();
-			return;
-		}
+			return set_interrupt_state(state);
 		advance_current_thread();
-		execute_current_thread();
+		execute_current_thread_locked();
 		ASSERT_NOT_REACHED();
 	}
 
 	void Scheduler::reschedule_if_idling()
 	{
-		VERIFY_CLI();
-
+		auto state = m_lock.lock();
 		if (m_active_threads.empty() || &current_thread() != m_idle_thread)
-			return;
-
+			return m_lock.unlock(state);
 		if (save_current_thread())
-			return;
+			return m_lock.unlock(state);
 		m_current_thread = m_active_threads.begin();
-		execute_current_thread();
+		execute_current_thread_locked();
 		ASSERT_NOT_REACHED();
 	}
 
 	void Scheduler::wake_threads()
 	{
-		VERIFY_CLI();
+		ASSERT(m_lock.is_locked());
 
 		uint64_t current_time = SystemTimer::get().ms_since_boot();
 		while (!m_sleeping_threads.empty() && m_sleeping_threads.front().wake_time <= current_time)
@@ -127,14 +110,22 @@ namespace Kernel
 
 	BAN::ErrorOr<void> Scheduler::add_thread(Thread* thread)
 	{
-		CriticalScope _;
+		SpinLockGuard _(m_lock);
 		TRY(m_active_threads.emplace_back(thread));
 		return {};
 	}
 
+	void Scheduler::terminate_thread(Thread* thread)
+	{
+		SpinLockGuard _(m_lock);
+		thread->m_state = Thread::State::Terminated;
+		if (thread == &current_thread())
+			execute_current_thread_locked();
+	}
+
 	void Scheduler::advance_current_thread()
 	{
-		VERIFY_CLI();
+		ASSERT(m_lock.is_locked());
 
 		if (m_active_threads.empty())
 		{
@@ -147,7 +138,7 @@ namespace Kernel
 
 	void Scheduler::remove_and_advance_current_thread()
 	{
-		VERIFY_CLI();
+		ASSERT(m_lock.is_locked());
 
 		ASSERT(m_current_thread);
 
@@ -168,7 +159,7 @@ namespace Kernel
 	//       after getting the rsp
 	ALWAYS_INLINE bool Scheduler::save_current_thread()
 	{
-		VERIFY_CLI();
+		ASSERT(m_lock.is_locked());
 
 		uintptr_t rsp, rip;
 		push_callee_saved();
@@ -190,7 +181,7 @@ namespace Kernel
 
 	void Scheduler::delete_current_process_and_thread()
 	{
-		DISABLE_INTERRUPTS();
+		m_lock.lock();
 
 		load_temp_stack();
 		PageTable::kernel().load();
@@ -204,23 +195,33 @@ namespace Kernel
 
 		delete thread;
 
-		execute_current_thread();
+		execute_current_thread_locked();
 		ASSERT_NOT_REACHED();
 	}
 
 	void Scheduler::execute_current_thread()
 	{
-		VERIFY_CLI();
-
+		m_lock.lock();
 		load_temp_stack();
 		PageTable::kernel().load();
-		_execute_current_thread();
+		execute_current_thread_stack_loaded();
 		ASSERT_NOT_REACHED();
 	}
 
-	NEVER_INLINE void Scheduler::_execute_current_thread()
+	void Scheduler::execute_current_thread_locked()
 	{
-		VERIFY_CLI();
+		load_temp_stack();
+		PageTable::kernel().load();
+		execute_current_thread_stack_loaded();
+		ASSERT_NOT_REACHED();
+	}
+
+	NEVER_INLINE void Scheduler::execute_current_thread_stack_loaded()
+	{
+		ASSERT(m_lock.is_locked());
+
+		load_temp_stack();
+		PageTable::kernel().load();
 
 #if SCHEDULER_VERIFY_STACK
 		vaddr_t rsp;
@@ -267,10 +268,12 @@ namespace Kernel
 		{
 			case Thread::State::NotStarted:
 				current->set_started();
+				m_lock.unlock(InterruptState::Disabled);
 				start_thread(current->rsp(), current->rip());
 			case Thread::State::Executing:
 				while (current->can_add_signal_to_execute())
 					current->handle_signal();
+				m_lock.unlock(InterruptState::Disabled);
 				continue_thread(current->rsp(), current->rip());
 			case Thread::State::Terminated:
 				ASSERT_NOT_REACHED();
@@ -281,11 +284,11 @@ namespace Kernel
 
 	void Scheduler::set_current_thread_sleeping_impl(uint64_t wake_time)
 	{
-		VERIFY_CLI();
+		ASSERT(m_lock.is_locked());
 
 		if (save_current_thread())
 		{
-			ENABLE_INTERRUPTS();
+			set_interrupt_state(InterruptState::Enabled);
 			return;
 		}
 
@@ -304,35 +307,27 @@ namespace Kernel
 		m_current_thread = {};
 		advance_current_thread();
 
-		execute_current_thread();
+		execute_current_thread_locked();
 		ASSERT_NOT_REACHED();
 	}
 
 	void Scheduler::set_current_thread_sleeping(uint64_t wake_time)
 	{
-		VERIFY_STI();
-		DISABLE_INTERRUPTS();
-
-		ASSERT(m_current_thread);
-
+		SpinLockGuard _(m_lock);
 		m_current_thread->semaphore = nullptr;
 		set_current_thread_sleeping_impl(wake_time);
 	}
 
 	void Scheduler::block_current_thread(Semaphore* semaphore, uint64_t wake_time)
 	{
-		VERIFY_STI();
-		DISABLE_INTERRUPTS();
-
-		ASSERT(m_current_thread);
-
+		SpinLockGuard _(m_lock);
 		m_current_thread->semaphore = semaphore;
 		set_current_thread_sleeping_impl(wake_time);
 	}
 
 	void Scheduler::unblock_threads(Semaphore* semaphore)
 	{
-		CriticalScope critical;
+		SpinLockGuard _(m_lock);
 
 		for (auto it = m_sleeping_threads.begin(); it != m_sleeping_threads.end();)
 		{
@@ -353,7 +348,7 @@ namespace Kernel
 
 	void Scheduler::unblock_thread(pid_t tid)
 	{
-		CriticalScope _;
+		SpinLockGuard _(m_lock);
 
 		for (auto it = m_sleeping_threads.begin(); it != m_sleeping_threads.end(); it++)
 		{

kernel/kernel/Storage/DiskCache.cpp

@@ -1,4 +1,3 @@
-#include <kernel/CriticalScope.h>
 #include <kernel/Lock/LockGuard.h>
 #include <kernel/Memory/Heap.h>
 #include <kernel/Memory/PageTable.h>

kernel/kernel/Terminal/Serial.cpp

@@ -1,5 +1,4 @@
 #include <BAN/Array.h>
-#include <kernel/CriticalScope.h>
 #include <kernel/Device/DeviceNumbers.h>
 #include <kernel/FS/DevFS/FileSystem.h>
 #include <kernel/IDT.h>
@@ -219,6 +218,8 @@ namespace Kernel
 	void SerialTTY::handle_irq()
 	{
 		uint8_t ch = IO::inb(m_serial.port());
+
+		SpinLockGuard _(m_input_lock);
 		if (m_input.full())
 		{
 			dwarnln("Serial buffer full");
@@ -235,7 +236,7 @@ namespace Kernel
 		uint8_t buffer[128];
 
 		{
-			CriticalScope _;
+			SpinLockGuard _(m_input_lock);
 			if (m_input.empty())
 				return;
 			uint8_t* ptr = buffer;

kernel/kernel/Thread.cpp

@@ -27,14 +27,6 @@ namespace Kernel
 			memcpy((void*)rsp, (void*)&value, sizeof(uintptr_t));
 	}
 
-	void Thread::terminate()
-	{
-		CriticalScope _;
-		m_state = Thread::State::Terminated;
-		if (this == &Thread::current())
-			Scheduler::get().execute_current_thread();
-	}
-
 	static pid_t s_next_tid = 1;
 
 	BAN::ErrorOr<Thread*> Thread::create_kernel(entry_t entry, void* data, Process* process)
@@ -193,9 +185,10 @@ namespace Kernel
 	{
 		m_state = State::NotStarted;
 		static entry_t entry(
-			[](void* process)
+			[](void* process_ptr)
 			{
-				((Process*)process)->cleanup_function();
+				auto& process = *reinterpret_cast<Process*>(process_ptr);
+				process.cleanup_function();
 				Scheduler::get().delete_current_process_and_thread();
 				ASSERT_NOT_REACHED();
 			}
@@ -245,10 +238,11 @@ namespace Kernel
 
 	void Thread::handle_signal(int signal)
 	{
-		ASSERT(!interrupts_enabled());
 		ASSERT(&Thread::current() == this);
 		ASSERT(is_userspace());
 
+		SpinLockGuard _(m_signal_lock);
+
 		auto& interrupt_stack = *reinterpret_cast<InterruptStack*>(interrupt_stack_base() + interrupt_stack_size() - sizeof(InterruptStack));
 		ASSERT(GDT::is_user_segment(interrupt_stack.cs));
 
@@ -338,7 +332,8 @@ namespace Kernel
 
 	bool Thread::add_signal(int signal)
 	{
-		ASSERT(!interrupts_enabled());
+		SpinLockGuard _(m_signal_lock);
+
 		uint64_t mask = 1ull << signal;
 		if (!(m_signal_block_mask & mask))
 		{
@@ -393,7 +388,7 @@ namespace Kernel
 	void Thread::on_exit()
 	{
 		ASSERT(this == &Thread::current());
-		terminate();
+		Scheduler::get().terminate_thread(this);
 		ASSERT_NOT_REACHED();
 	}
 

kernel/kernel/Timer/HPET.cpp

@@ -244,7 +244,7 @@ namespace Kernel
 		if (m_is_64bit)
 			return regs.main_counter.full;
 
-		CriticalScope _;
+		SpinLockGuard _(m_lock);
 		uint32_t current_low = regs.main_counter.low;
 		uint32_t wraps = m_32bit_wraps;
 		if (current_low < (uint32_t)m_last_ticks)
@@ -256,19 +256,21 @@ namespace Kernel
 	{
 		auto& regs = registers();
 
-		uint64_t current_ticks;
-
-		if (m_is_64bit)
-			current_ticks = regs.main_counter.full;
-		else
 		{
-			uint32_t current_low = regs.main_counter.low;
-			if (current_low < (uint32_t)m_last_ticks)
-				m_32bit_wraps++;
-			current_ticks = ((uint64_t)m_32bit_wraps << 32) | current_low;
-		}
+			SpinLockGuard _(m_lock);
 
-		m_last_ticks = current_ticks;
+			uint64_t current_ticks;
+			if (m_is_64bit)
+				current_ticks = regs.main_counter.full;
+			else
+			{
+				uint32_t current_low = regs.main_counter.low;
+				if (current_low < (uint32_t)m_last_ticks)
+					m_32bit_wraps++;
+				current_ticks = ((uint64_t)m_32bit_wraps << 32) | current_low;
+			}
+			m_last_ticks = current_ticks;
+		}
 
 		Scheduler::get().timer_reschedule();
 	}

kernel/kernel/kernel.cpp

@@ -82,7 +82,7 @@ extern "C" void kernel_main(uint32_t boot_magic, uint32_t boot_info)
 {
 	using namespace Kernel;
 
-	DISABLE_INTERRUPTS();
+	set_interrupt_state(InterruptState::Disabled);
 
 	if (!validate_boot_magic(boot_magic))
 	{