From 920bd0748827d93ec992b3e11be72937f05b4509 Mon Sep 17 00:00:00 2001
From: Michael Mueller <michael.mueller@uos.de>
Date: Thu, 17 Apr 2025 15:42:51 +0200
Subject: [PATCH] Added spinlock from NOVA for locking CIP.

---
 repos/base-tukija/include/tukija/spinlock.hpp | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 repos/base-tukija/include/tukija/spinlock.hpp

diff --git a/repos/base-tukija/include/tukija/spinlock.hpp b/repos/base-tukija/include/tukija/spinlock.hpp
new file mode 100644
index 0000000000..8d6d56a89a
--- /dev/null
+++ b/repos/base-tukija/include/tukija/spinlock.hpp
@@ -0,0 +1,52 @@
+/*
+ * Generic Spinlock
+ *
+ * Copyright (C) 2009-2011 Udo Steinberg <udo@hypervisor.org>
+ * Economic rights: Technische Universitaet Dresden (Germany)
+ *
+ * This file is part of the NOVA microhypervisor.
+ *
+ * NOVA is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * NOVA is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License version 2 for more details.
+ */
+
+#pragma once
+
+namespace Tukija {
+    class Spinlock;
+}
+
+class Tukija::Spinlock
+{
+    private:
+        unsigned short val;
+
+    public:
+        inline Spinlock() : val (0) {}
+
+        __attribute__((noinline))
+        void lock()
+        {
+            unsigned short tmp = 0x100;
+
+            asm volatile ("     lock; xadd %0, %1;  "
+                          "1:   cmpb %h0, %b0;      "
+                          "     je 2f;              "
+                          "     pause;              "
+                          "     movb %1, %b0;       "
+                          "     jmp 1b;             "
+                          "2:                       "
+                          : "+Q" (tmp), "+m" (val) : : "memory");
+        }
+
+        inline void unlock()
+        {
+            asm volatile ("incb %0" : "+m" (val) : : "memory");
+        }
+};