os: rework kernel architecture

Rework the code structure and architecture of the kernel by separating
platform-dependent and platform-independent code more cleanly. As of
this patchset, full feature parity has not been achieved. Nonetheless, a
sufficient subset of functionality has been ported to the new
architecture to demonstrate the feasibility of the new structure.

83 files changed, 1536 insertions, 5634 deletions

diff --git a/arch/x86_64/include/arch/boot/pointers.hpp b/arch/x86_64/include/arch/boot/pointers.hpp
deleted file mode 100644
index fe9c657..0000000
--- a/arch/x86_64/include/arch/boot/pointers.hpp
+++ /dev/null
@@ -1,15 +0,0 @@
-#ifndef TEACHOS_ARCH_X86_64_BOOT_POINTERS_HPP
-#define TEACHOS_ARCH_X86_64_BOOT_POINTERS_HPP
-
-#include <cstddef>
-
-namespace teachos::arch::boot
-{
-  /**
-   * @brief Address pointing to the start of the multiboot information structure.
-   */
-  extern "C" size_t const multiboot_information_pointer;
-
-}  // namespace teachos::arch::boot
-
-#endif  // TEACHOS_ARCH_X86_64_BOOT_POINTERS_HPP
diff --git a/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/gate_descriptor.hpp b/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/gate_descriptor.hpp
deleted file mode 100644
index 07110c8..0000000
--- a/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/gate_descriptor.hpp
+++ /dev/null
@@ -1,69 +0,0 @@
-#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_GATE_DESCRIPTOR_HPP
-#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_GATE_DESCRIPTOR_HPP
-
-#include "arch/context_switching/interrupt_descriptor_table/idt_flags.hpp"
-#include "arch/context_switching/interrupt_descriptor_table/ist_offset.hpp"
-#include "arch/context_switching/interrupt_descriptor_table/segment_selector.hpp"
-
-#include <bitset>
-#include <cstdint>
-
-namespace teachos::arch::context_switching::interrupt_descriptor_table
-{
-  __extension__ typedef __int128 int128_t;
-  __extension__ typedef unsigned __int128 uint128_t;
-
-  /**
-   * @brief Defines helper function for all states and the actual data the gate descriptor can have.
-   */
-  struct [[gnu::packed]] gate_descriptor
-  {
-    /**
-     * @brief Default Constructor.
-     */
-    gate_descriptor() = default;
-
-    /**
-     * @brief Constructor.
-     *
-     * @note Created gate descriptor copies the given bytes into these components ending with a 32 bit reserved
-     * field that has to be used, because the 64-bit gate descriptor needs to be big enough for two 32-bit gate
-     * descriptor.
-     * - 16 bit Segment Selector
-     * - 3 bit Interrupt Stack Table Offset
-     * - 8 bit Type and Flags
-     * - 64 bit Offset
-     *
-     * @param flags Copies the bits set from the given data into the individual components of a gate
-     * descriptor.
-     */
-    explicit gate_descriptor(uint128_t flags);
-
-    /**
-     * @brief Constructor.
-     *
-     * @param selector, ist, flags, offset Copies the bits set from the given data into the individual components of
-     * a gate descriptor.
-     */
-    gate_descriptor(segment_selector selector, ist_offset ist, idt_flags flags, uint64_t offset);
-
-    /**
-     * @brief Allows to compare the underlying bits of two instances.
-     *
-     * @param other Other instance that we want to compare with.
-     * @return Whether the underlying set bits of both types are the same.
-     */
-    auto operator==(gate_descriptor const & other) const -> bool = default;
-
-  private:
-    // The order in private variables starts for the first variable being the rightmost bit.
-    uint16_t _offset_1 = {};          ///< Lower 16 bits of handler function address (0 - 15)
-    segment_selector _selector = {};  ///< Segment selector (16 - 31)
-    ist_offset _ist = {};             ///< Interrupt Stack Table offset (32 - 39)
-    idt_flags _flags = {};            ///< Gate Type and Flags (40 - 47)
-    uint64_t _offset_2 : 48 = {};     ///< Upper 48 bits of handler function address (48 - 95)
-    uint32_t : 32;                    ///< Reserved field used to ensure this struct is 128 bits big (96 - 127)
-  };
-}  // namespace teachos::arch::context_switching::interrupt_descriptor_table
-
-#endif  // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_GATE_DESCRIPTOR_HPP
diff --git a/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/idt_flags.hpp b/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/idt_flags.hpp
deleted file mode 100644
index 5104c36..0000000
--- a/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/idt_flags.hpp
+++ /dev/null
@@ -1,81 +0,0 @@
-
-#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_IDT_FLAGS_HPP
-#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_IDT_FLAGS_HPP
-
-#include <bitset>
-#include <cstdint>
-
-namespace teachos::arch::context_switching::interrupt_descriptor_table
-{
-  /**
-   * @brief Defines helper function for all states that the access byte field of a segment descriptor can
-   * have.
-   */
-  struct [[gnu::packed]] idt_flags
-  {
-    /**
-     * @brief Possible set bits in our underlying bits and the meaning when they are set.
-     */
-    enum bitset : uint8_t
-    {
-      INTERRUPT_GATE = 0b01110,  ///< The actual type of gate segment is a interrupt gate.
-      TRAP_GATE = 0b01111,       ///< The actual type of gate segment is a trap gate.
-      DESCRIPTOR_LEVEL_KERNEL =
-          0U << 5U,  ///< Highest privileged level used by the kernel to allow for full access of resources.
-      DESCRIPTOR_LEVEL_ADMIN =
-          1U << 5U,  ///< Restricts access to own application and thoose of lower privilege. Should only be used if more
-                     ///< than two privilege levels are required, otherwise using Level 3 and Level 0 is recommended.
-      DESCRIPTOR_LEVEL_PRIVILEGED_USER =
-          2U << 5U,  ///< Restricts access to own application and thoose of lower privilege. Should only be used if more
-                     ///< than two privilege levels are required, otherwise using Level 3 and Level 0 is recommended.
-      DESCRIPTOR_LEVEL_USER = 3U << 5U,  ///< Restricts access to only application and their specific memory.
-      PRESENT = 1U << 7U,                ///< Present bit; Allows an entry to refer to a valid segment.
-                                         ///< Must be set (1) for any valid segment.
-    };
-
-    /**
-     * @brief Default Constructor.
-     */
-    idt_flags() = default;
-
-    /**
-     * @brief Constructor.
-     *
-     * @param flags Allows to set flags for the access byte field using the unscoped enum contained in this class, used
-     * to allow for direct integer conversion. This value is saved and can later be used to check whether certain flags
-     * are enabled or not using contains_flags method.
-     */
-    idt_flags(uint8_t flags);
-
-    /**
-     * @brief Checks if the given std::bitset is a subset or equivalent to the underlying data.
-     *
-     * @note Meaning that all bits that are set in the given std::bitset also have to be set in the underlyng
-     * data. Any additional bits that are set are not relevant.
-     *
-     * @param other Flags that we want to compare against and check if the underlying data has the same bits set.
-     * @return Whether the given flags are a subset or equivalent with the underlying data.
-     */
-    auto contains_flags(std::bitset<8U> other) const -> bool;
-
-    /**
-     * @brief Allows to compare the underlying bits of two instances.
-     *
-     * @param other Other instance that we want to compare with.
-     * @return Whether the underlying set bits of both types are the same.
-     */
-    auto operator==(idt_flags const & other) const -> bool = default;
-
-    /**
-     * @brief Combines all bits that are set in the std::bitset flags with the bits already set in the underlying data.
-     *
-     * @param other Additional bits that should be set.
-     */
-    auto operator|=(std::bitset<8U> other) -> void;
-
-  private:
-    uint8_t _flags = {};  ///< Underlying bits used to read the flags from.
-  };
-}  // namespace teachos::arch::context_switching::interrupt_descriptor_table
-
-#endif  // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_IDT_FLAGS_HPP
\ No newline at end of file
diff --git a/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.hpp b/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.hpp
deleted file mode 100644
index b388e0e..0000000
--- a/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.hpp
+++ /dev/null
@@ -1,24 +0,0 @@
-#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_HPP
-#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_HPP
-
-#include "arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.hpp"
-
-namespace teachos::arch::context_switching::interrupt_descriptor_table
-{
-  /**
-   * @brief Updates the IDTR with the created interrupt descriptor table. If it has not been created yet this
-   * method will create it.
-   */
-  auto update_interrupt_descriptor_table_register() -> void;
-
-  /**
-   * @brief Creates the interrupt descriptor table, with the minimum required configuration. If this method is called
-   * more than once, the previously created instance is returned instead.
-   *
-   * @return Reference to the created interrupt_descriptor_table.
-   */
-  auto get_or_create_interrupt_descriptor_table() -> interrupt_descriptor_table &;
-
-}  // namespace teachos::arch::context_switching::interrupt_descriptor_table
-
-#endif  // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_HPP
diff --git a/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.hpp b/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.hpp
deleted file mode 100644
index 7fe933b..0000000
--- a/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/interrupt_descriptor_table_pointer.hpp
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_POINTER_HPP
-#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_INTERRUPT_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_POINTER_HPP
-
-#include "arch/context_switching/interrupt_descriptor_table/gate_descriptor.hpp"
-#include "arch/stl/vector.hpp"
-
-namespace teachos::arch::context_switching::interrupt_descriptor_table
-{
-  using interrupt_descriptor_table = stl::vector<gate_descriptor>;
-
-  /**
-   * @brief Represents a pointer to the Interrupt Descriptor Table (IDT).
-   *
-   * This structure is used to store the base address and length of the IDT.
-   */
-  struct [[gnu::packed]] interrupt_descriptor_table_pointer
-  {
-    /**
-     * @brief Default constructor.
-     */
-    interrupt_descriptor_table_pointer() = default;
-
-    /**</