Add spinlocks

kernel/include/thread/Spinlock.h

@@ -0,0 +1,15 @@
+#pragma once
+#include <stdint.h>
+
+struct Spinlock
+{
+  public:
+    void acquire();
+    void release();
+    bool locked();
+
+  private:
+    volatile uint64_t m_lock = 0;
+};
+
+void lock(Spinlock& lock, void (*action)(void));

kernel/src/thread/Spinlock.asm

@@ -0,0 +1,26 @@
+global spinlock_lock_acquire
+spinlock_lock_acquire:
+    lock bts qword [rdi], 0
+    jc .spin
+    ret
+.spin:
+    pause
+    test qword [rdi], 1
+    jnz .spin
+    jmp spinlock_lock_acquire
+
+global spinlock_lock_release
+spinlock_lock_release:
+    mov qword [rdi], 0
+    ret
+
+global spinlock_lock_is_locked
+spinlock_lock_is_locked:
+    cmp qword [rdi], 0
+    je .free
+.locked:
+    mov rax, 1
+    ret
+.free:
+    mov rax, 0
+    ret

kernel/src/thread/Spinlock.cpp

@@ -0,0 +1,27 @@
+#include "thread/Spinlock.h"
+
+extern "C" void spinlock_lock_acquire(uint64_t* lock);
+extern "C" void spinlock_lock_release(uint64_t* lock);
+extern "C" int spinlock_lock_is_locked(uint64_t* lock);
+
+void Spinlock::acquire()
+{
+    spinlock_lock_acquire(&m_lock);
+}
+
+void Spinlock::release()
+{
+    spinlock_lock_release(&m_lock);
+}
+
+bool Spinlock::locked()
+{
+    return spinlock_lock_is_locked(&m_lock);
+}
+
+void lock(Spinlock& lock, void (*action)(void))
+{
+    lock.acquire();
+    action();
+    lock.release();
+}