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

No functional change.

Kernel/Arch/x86_64/DescriptorTable.h

@@ -0,0 +1,155 @@
+/*
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Leon Albrecht <leon2002.la@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/StdLibExtras.h>
+#include <AK/Types.h>
+#include <Kernel/VirtualAddress.h>
+
+#include <AK/Platform.h>
+VALIDATE_IS_X86()
+
+// Note: These values are x86-64.
+#define GDT_SELECTOR_CODE0 0x08
+#define GDT_SELECTOR_DATA0 0x10
+#define GDT_SELECTOR_DATA3 0x18
+#define GDT_SELECTOR_CODE3 0x20
+#define GDT_SELECTOR_TSS 0x28
+#define GDT_SELECTOR_TSS_PART2 0x30
+
+namespace Kernel {
+
+struct [[gnu::packed]] DescriptorTablePointer {
+    u16 limit;
+    void* address;
+};
+
+union [[gnu::packed]] Descriptor {
+    struct {
+        u16 limit_lo;
+        u16 base_lo;
+        u8 base_hi;
+        u8 type : 4;
+        u8 descriptor_type : 1;
+        u8 dpl : 2;
+        u8 segment_present : 1;
+        u8 limit_hi : 4;
+        u8 : 1;
+        u8 operation_size64 : 1;
+        u8 operation_size32 : 1;
+        u8 granularity : 1;
+        u8 base_hi2;
+    };
+    struct {
+        u32 low;
+        u32 high;
+    };
+
+    enum SystemType {
+        Invalid = 0,
+        AvailableTSS_16bit = 0x1,
+        LDT = 0x2,
+        BusyTSS_16bit = 0x3,
+        CallGate_16bit = 0x4,
+        TaskGate = 0x5,
+        InterruptGate_16bit = 0x6,
+        TrapGate_16bit = 0x7,
+        AvailableTSS = 0x9,
+        BusyTSS = 0xb,
+        CallGate = 0xc,
+        InterruptGate = 0xe,
+        TrapGate = 0xf,
+    };
+
+    VirtualAddress base() const
+    {
+        FlatPtr base = base_lo;
+        base |= base_hi << 16u;
+        base |= base_hi2 << 24u;
+        return VirtualAddress { base };
+    }
+
+    void set_base(VirtualAddress base)
+    {
+        base_lo = base.get() & 0xffffu;
+        base_hi = (base.get() >> 16u) & 0xffu;
+        base_hi2 = (base.get() >> 24u) & 0xffu;
+        VERIFY(base.get() <= 0xffffffff);
+    }
+
+    void set_limit(u32 length)
+    {
+        limit_lo = length & 0xffff;
+        limit_hi = (length >> 16) & 0xf;
+    }
+};
+
+static_assert(AssertSize<Descriptor, 8>());
+
+enum class IDTEntryType {
+    TaskGate32 = 0b0101,
+    InterruptGate16 = 0b110,
+    TrapGate16 = 0b111,
+    InterruptGate32 = 0b1110,
+    TrapGate32 = 0b1111,
+};
+
+// Clang doesn't format this right due to the compiler magic
+// clang-format off
+struct [[gnu::packed]] IDTEntry
+{
+    u16 offset_1; // offset bits 0..15
+    u16 selector; // a code segment selector in GDT or LDT
+
+    struct {
+        u8 interrupt_stack_table : 3;
+        u8 zero : 5; // unused, set to 0
+    };
+
+    struct {
+        u8 gate_type : 4;
+        u8 storage_segment : 1;
+        u8 descriptor_privilege_level : 2;
+        u8 present : 1;
+    } type_attr;  // type and attributes
+    u16 offset_2; // offset bits 16..31
+    u32 offset_3;
+    u32 zeros;
+
+    IDTEntry() = default;
+    IDTEntry(FlatPtr callback, u16 selector_, IDTEntryType type, u8 storage_segment, u8 privilege_level)
+        : offset_1 { (u16)((FlatPtr)callback & 0xFFFF) }
+        , selector { selector_ }
+        , interrupt_stack_table { 0 }
+        , zero { 0 }
+        , type_attr {
+            .gate_type = (u8)type,
+            .storage_segment = storage_segment,
+            .descriptor_privilege_level = (u8)(privilege_level & 0b11),
+            .present = 1,
+        }
+        , offset_2 { (u16)((FlatPtr)callback >> 16) }
+        , offset_3 { (u32)(((FlatPtr)callback) >> 32) }
+        , zeros { 0 }
+    {
+    }
+
+    FlatPtr off() const
+    {
+        return (u64)offset_3 << 32 & (u64)offset_2 << 16 & (u64)offset_1;
+    }
+    IDTEntryType type() const
+    {
+        return IDTEntryType(type_attr.gate_type);
+    }
+};
+// clang-format on
+
+static_assert(AssertSize<IDTEntry, 2 * sizeof(void*)>());
+
+}