[Zion] Add a mutex object with appropriate syscalls.

zion/object/mutex.h

@@ -0,0 +1,55 @@
+#pragma once
+
+#include <glacier/container/intrusive_list.h>
+#include <glacier/memory/ref_ptr.h>
+
+#include "include/ztypes.h"
+#include "object/kernel_object.h"
+#include "object/thread.h"
+
+class Mutex;
+
+template <>
+struct KernelObjectTag<Mutex> {
+  static const uint64_t type = KernelObject::MUTEX;
+};
+
+class Mutex : public KernelObject {
+ public:
+  uint64_t TypeTag() override { return KernelObject::MUTEX; }
+  static uint64_t DefaultPermissions() {
+    return kZionPerm_Lock | kZionPerm_Release;
+  }
+
+  static glcr::RefPtr<Mutex> Create();
+
+  // Attempts to lock the mutex, suspends the current thread
+  // until the lock is acquired.
+  void Lock();
+
+  // Releases the mutex and activates the next thread in the
+  // blocked queue if it exists.
+  void Release();
+
+ private:
+  uint8_t lock_ = 0;
+
+  glcr::IntrusiveList<Thread> blocked_threads_;
+
+  Mutex() {}
+};
+
+class MutexHolder {
+ public:
+  MutexHolder(const glcr::RefPtr<Mutex>& mutex) : mutex_(mutex) {
+    mutex_->Lock();
+  }
+
+  ~MutexHolder() { mutex_->Release(); }
+
+  MutexHolder(MutexHolder&) = delete;
+  MutexHolder(MutexHolder&&) = delete;
+
+ private:
+  glcr::RefPtr<Mutex> mutex_;
+};