Kernel: Add enum InterruptsState and helper functions

This commit adds the concept of an InterruptsState to the kernel. This
will be used to make the Spinlock code architecture independent. A new
Processor.cpp file is added such that we don't have to duplicate the
code.

Kernel/Arch/Processor.cpp

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2022, Timon Kruiper <timonkruiper@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/Arch/Processor.h>
+
+namespace Kernel {
+
+// FIXME: Move the InterruptsState related functions inside the Processor class, when we have a generic Processor base class.
+InterruptsState processor_interrupts_state()
+{
+    return Processor::are_interrupts_enabled() ? InterruptsState::Enabled : InterruptsState::Disabled;
+}
+
+void restore_processor_interrupts_state(InterruptsState interrupts_state)
+{
+    if (interrupts_state == InterruptsState::Enabled)
+        Processor::enable_interrupts();
+    else
+        Processor::disable_interrupts();
+}
+
+}

Kernel/Arch/Processor.h

@@ -10,6 +10,19 @@
 #include <AK/Function.h>
 #include <Kernel/Arch/DeferredCallEntry.h>
 
+namespace Kernel {
+
+// FIXME: Move the InterruptsState enum and related functions inside the Processor class.
+enum class InterruptsState {
+    Enabled,
+    Disabled
+};
+
+InterruptsState processor_interrupts_state();
+void restore_processor_interrupts_state(InterruptsState);
+
+}
+
 #if ARCH(X86_64) || ARCH(I386)
 #    include <Kernel/Arch/x86/Processor.h>
 #elif ARCH(AARCH64)

Kernel/CMakeLists.txt

@@ -329,6 +329,8 @@ set(KERNEL_SOURCES
 if ("${SERENITY_ARCH}" STREQUAL "i686" OR "${SERENITY_ARCH}" STREQUAL "x86_64")
     set(KERNEL_SOURCES
         ${KERNEL_SOURCES}
+        Arch/Processor.cpp
+
         Arch/x86/common/ScopedCritical.cpp
         Arch/x86/common/SmapDisabler.cpp
         Arch/x86/common/Spinlock.cpp
@@ -443,6 +445,8 @@ else()
         ${AK_SOURCES}
         ${RPI_SOURCES}
 
+        Arch/Processor.cpp
+
         Arch/aarch64/boot.S
         Arch/aarch64/BootPPMParser.cpp
         Arch/aarch64/CrashHandler.cpp