Kernel: Reorganize Arch/x86 directory to Arch/x86_64 after i686 removal

No functional change.

Kernel/Arch/x86_64/CPU.h

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Atomic.h>
+#include <AK/Concepts.h>
+#include <AK/Vector.h>
+
+#include <Kernel/Arch/x86_64/DescriptorTable.h>
+
+#include <AK/Platform.h>
+VALIDATE_IS_X86()
+
+/* Map IRQ0-15 @ ISR 0x50-0x5F */
+#define IRQ_VECTOR_BASE 0x50
+#define GENERIC_INTERRUPT_HANDLERS_COUNT (256 - IRQ_VECTOR_BASE)
+
+namespace Kernel {
+
+struct RegisterState;
+class GenericInterruptHandler;
+
+static constexpr u32 safe_eflags_mask = 0xdff;
+static constexpr u32 iopl_mask = 3u << 12;
+
+inline u32 get_iopl_from_eflags(u32 eflags)
+{
+    return (eflags & iopl_mask) >> 12;
+}
+
+DescriptorTablePointer const& get_gdtr();
+DescriptorTablePointer const& get_idtr();
+
+constexpr FlatPtr page_base_of(FlatPtr address)
+{
+    return address & PAGE_MASK;
+}
+
+inline FlatPtr page_base_of(void const* address)
+{
+    return page_base_of((FlatPtr)address);
+}
+
+constexpr FlatPtr offset_in_page(FlatPtr address)
+{
+    return address & (~PAGE_MASK);
+}
+
+inline FlatPtr offset_in_page(void const* address)
+{
+    return offset_in_page((FlatPtr)address);
+}
+
+}