Merge branch 'develop-BA-FS26' into 'develop'HEADdevelop

Merge of BA-FS26 branch into develop

See merge request teachos/kernel!49

20 files changed, 844 insertions, 0 deletions

diff --git a/kernel/src/test_support/devices/block_device.cpp b/kernel/src/test_support/devices/block_device.cpp
new file mode 100644
index 0000000..9a9e544
--- /dev/null
+++ b/kernel/src/test_support/devices/block_device.cpp
@@ -0,0 +1,61 @@
+#include <kernel/test_support/devices/block_device.hpp>
+
+#include <kernel/devices/block_device.hpp>
+
+#include <kstd/string>
+#include <kstd/vector>
+
+#include <algorithm>
+#include <cstddef>
+#include <cstdint>
+#include <cstring>
+#include <string.h>
+
+namespace kernel::tests::devices
+{
+  block_device::block_device(size_t major, size_t minor, kstd::string const & name, size_t block_size,
+                             size_t initial_size)
+      : kernel::devices::block_device(major, minor, name, block_size)
+  {
+    data.resize(initial_size, 0);
+  }
+
+  auto block_device::init() -> bool
+  {
+    return true;
+  }
+
+  auto block_device::read_block(size_t block_index, void * buffer) const -> void
+  {
+    auto const offset = block_index * block_size();
+    if (offset >= data.size())
+    {
+      kstd::libc::memset(buffer, 0, block_size());
+      return;
+    }
+
+    auto const bytes_to_read = std::min(block_size(), data.size() - offset);
+    kstd::libc::memcpy(buffer, data.data() + offset, bytes_to_read);
+    if (bytes_to_read < block_size())
+    {
+      kstd::libc::memset(static_cast<uint8_t *>(buffer) + bytes_to_read, 0, block_size() - bytes_to_read);
+    }
+  }
+
+  auto block_device::write_block(size_t block_index, void const * buffer) -> void
+  {
+    auto const offset = block_index * block_size();
+    auto const write_end = offset + block_size();
+    if (write_end > data.size())
+    {
+      data.resize(write_end, 0);
+    }
+
+    kstd::libc::memcpy(data.data() + offset, static_cast<uint8_t const *>(buffer), block_size());
+  }
+
+  auto block_device::size() const -> size_t
+  {
+    return data.size();
+  }
+}  // namespace kernel::tests::devices
\ No newline at end of file
diff --git a/kernel/src/test_support/devices/character_device.cpp b/kernel/src/test_support/devices/character_device.cpp
new file mode 100644
index 0000000..3806654
--- /dev/null
+++ b/kernel/src/test_support/devices/character_device.cpp
@@ -0,0 +1,19 @@
+#include <kernel/test_support/devices/character_device.hpp>
+
+#include <kapi/devices.hpp>
+
+#include <kstd/string>
+
+#include <cstddef>
+
+namespace kernel::tests::devices
+{
+  character_device::character_device(size_t major, size_t minor, kstd::string const & name)
+      : kapi::devices::device(major, minor, name)
+  {}
+
+  auto character_device::init() -> bool
+  {
+    return true;
+  }
+}  // namespace kernel::tests::devices
\ No newline at end of file
diff --git a/kernel/src/test_support/filesystem/ext2.cpp b/kernel/src/test_support/filesystem/ext2.cpp
new file mode 100644
index 0000000..52b6efe
--- /dev/null
+++ b/kernel/src/test_support/filesystem/ext2.cpp
@@ -0,0 +1,68 @@
+#include <kernel/test_support/filesystem/ext2.hpp>
+
+#include <kernel/filesystem/ext2/block_group_descriptor.hpp>
+#include <kernel/filesystem/ext2/filesystem.hpp>
+#include <kernel/filesystem/ext2/inode.hpp>
+#include <kernel/filesystem/ext2/superblock.hpp>
+#include <kernel/test_support/devices/block_device.hpp>
+
+#include <cstdint>
+#include <cstring>
+
+namespace kernel::tests::filesystem::ext2
+{
+  namespace
+  {
+    constexpr uint32_t root_directory_data_block = 20;
+  }  // namespace
+
+  auto write_bytes(kernel::tests::devices::block_device & device, size_t offset, void const * source, size_t size)
+      -> void
+  {
+    auto const required_size = offset + size;
+    if (device.data.size() < required_size)
+    {
+      device.data.resize(required_size, 0);
+    }
+
+    std::memcpy(device.data.data() + offset, source, size);
+  }
+
+  auto write_u32(kernel::tests::devices::block_device & device, size_t offset, uint32_t value) -> void
+  {
+    write_bytes(device, offset, &value, sizeof(value));
+  }
+
+  auto setup_mock_ext2_layout(kernel::tests::devices::block_device & device) -> void
+  {
+    auto superblock = kernel::filesystem::ext2::superblock{};
+    superblock.magic = kernel::filesystem::ext2::constants::magic_number;
+    superblock.log_block_size = 0;
+    superblock.blocks_count = 64;
+    superblock.blocks_per_group = 64;
+    superblock.inodes_per_group = 32;
+    superblock.rev_level = 1;
+    superblock.inode_size = 128;
+    setup_mock_ext2_layout(device, superblock);
+  }
+
+  auto setup_mock_ext2_layout(kernel::tests::devices::block_device & device,
+                              kernel::filesystem::ext2::superblock const & superblock) -> void
+  {
+    write_bytes(device, kernel::filesystem::ext2::constants::superblock_offset, &superblock, sizeof(superblock));
+
+    auto group_descriptor = kernel::filesystem::ext2::block_group_descriptor{};
+    group_descriptor.inode_table = 5;
+    write_bytes(device, 2048, &group_descriptor, sizeof(group_descriptor));
+
+    auto root_inode_data = kernel::filesystem::ext2::inode_data{};
+    root_inode_data.mode = kernel::filesystem::ext2::constants::mode_directory;
+    root_inode_data.blocks = 2;
+    root_inode_data.block[0] = root_directory_data_block;
+
+    auto const root_inode_offset =
+        static_cast<size_t>(group_descriptor.inode_table) * kernel::filesystem::ext2::constants::base_block_size +
+        (kernel::filesystem::ext2::constants::root_inode_number - 1) * superblock.inode_size;
+    write_bytes(device, root_inode_offset, &root_inode_data, sizeof(root_inode_data));
+  }
+}  // namespace kernel::tests::filesystem::ext2
\ No newline at end of file
diff --git a/kernel/src/test_support/filesystem/filesystem.cpp b/kernel/src/test_support/filesystem/filesystem.cpp
new file mode 100644
index 0000000..ec70607
--- /dev/null
+++ b/kernel/src/test_support/filesystem/filesystem.cpp
@@ -0,0 +1,17 @@
+#include <kernel/test_support/filesystem/filesystem.hpp>
+
+#include <kernel/filesystem/inode.hpp>
+#include <kernel/test_support/filesystem/inode.hpp>
+
+#include <kstd/memory>
+
+#include <string_view>
+
+namespace kernel::tests::filesystem
+{
+  auto filesystem::lookup(kstd::shared_ptr<kernel::filesystem::inode> const &, std::string_view) const
+      -> kstd::shared_ptr<kernel::filesystem::inode>
+  {
+    return kstd::make_shared<inode>();
+  }
+}  // namespace kernel::tests::filesystem
\ No newline at end of file
diff --git a/kernel/src/test_support/filesystem/inode.cpp b/kernel/src/test_support/filesystem/inode.cpp
new file mode 100644
index 0000000..0c8d956
--- /dev/null
+++ b/kernel/src/test_support/filesystem/inode.cpp
@@ -0,0 +1,23 @@
+#include <kernel/test_support/filesystem/inode.hpp>
+
+#include <kernel/filesystem/inode.hpp>
+
+#include <cstddef>
+
+namespace kernel::tests::filesystem
+{
+  auto inode::read(void *, size_t, size_t size) const -> size_t
+  {
+    return size;
+  }
+
+  auto inode::write(void const *, size_t, size_t size) -> size_t
+  {
+    return size;
+  }
+
+  auto inode::is_regular() const -> bool
+  {
+    return true;
+  }
+}  // namespace kernel::tests::filesystem
\ No newline at end of file
diff --git a/kernel/src/test_support/filesystem/storage_boot_module_fixture.cpp b/kernel/src/test_support/filesystem/storage_boot_module_fixture.cpp
new file mode 100644
index 0000000..aabaace
--- /dev/null
+++ b/kernel/src/test_support/filesystem/storage_boot_module_fixture.cpp
@@ -0,0 +1,139 @@
+#include <kernel/test_support/filesystem/storage_boot_module_fixture.hpp>
+
+#include <kernel/devices/storage/management.hpp>
+#include <kernel/test_support/boot_modules.hpp>
+#include <kernel/test_support/devices/storage/management.hpp>
+
+#include <kapi/boot_module/boot_module.hpp>
+#include <kapi/boot_modules.hpp>
+#include <kapi/memory.hpp>
+
+#include <cstddef>
+#include <fcntl.h>
+#include <filesystem>
+#include <format>
+#include <stdexcept>
+#include <string>
+#include <unistd.h>
+#include <utility>
+#include <vector>
+
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+namespace kernel::tests::filesystem
+{
+  storage_boot_module_fixture::mapped_image::mapped_image(std::filesystem::path path)
+      : file_descriptor(::open(path.c_str(), O_RDWR))
+  {
+    if (file_descriptor < 0)
+    {
+      throw std::runtime_error{"Failed to open image file for test boot module: " + path.string()};
+    }
+
+    struct stat statistics{};
+    if (::fstat(file_descriptor, &statistics) < 0)
+    {
+      throw std::runtime_error{"Failed to get statistics for image file: " + path.string()};
+    }
+
+    size = static_cast<std::size_t>(statistics.st_size);
+
+    mapping = static_cast<std::byte *>(::mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, file_descriptor, 0));
+    if (mapping == MAP_FAILED)
+    {
+      throw std::runtime_error{"Failed to map image file for test boot module: " + path.string()};
+    }
+  }
+
+  storage_boot_module_fixture::mapped_image::~mapped_image()
+  {
+    if (mapping != nullptr)
+    {
+      ::munmap(mapping, size);
+    }
+    if (file_descriptor >= 0)
+    {
+      ::close(file_descriptor);
+    }
+  }
+
+  storage_boot_module_fixture::mapped_image::mapped_image(mapped_image && other) noexcept
+      : file_descriptor{std::exchange(other.file_descriptor, -1)}
+      , mapping{std::exchange(other.mapping, nullptr)}
+      , size{std::exchange(other.size, 0)}
+  {}
+
+  auto storage_boot_module_fixture::mapped_image::operator=(mapped_image && other) noexcept -> mapped_image &
+  {
+    if (this != &other)
+    {
+      file_descriptor = std::exchange(other.file_descriptor, -1);
+      mapping = std::exchange(other.mapping, nullptr);
+      size = std::exchange(other.size, 0);
+    }
+    return *this;
+  }
+
+  storage_boot_module_fixture::~storage_boot_module_fixture()
+  {
+    kernel::tests::devices::storage::management::deinit();
+    kernel::tests::boot_modules::deinit();
+  }
+
+  auto storage_boot_module_fixture::setup_modules(std::size_t module_count, std::size_t module_size) -> void
+  {
+    m_module_names.clear();
+    m_module_data.clear();
+    m_registry = {};
+
+    m_module_names.reserve(module_count);
+    m_module_data.reserve(module_count);
+
+    for (std::size_t i = 0; i < module_count; ++i)
+    {
+      m_module_names.push_back(std::format("test_mod{}", i));
+      m_module_data.emplace_back(module_size, std::byte{static_cast<unsigned char>(0x40 + (i % 16))});
+    }
+
+    for (std::size_t i = 0; i < module_count; ++i)
+    {
+      m_registry.add_boot_module(kapi::boot_modules::boot_module{
+        m_module_names[i].c_str(), kapi::memory::linear_address{m_module_data[i].data()}, m_module_data[i].size()});
+    }
+
+    kapi::boot_modules::set_boot_module_registry(m_registry);
+    kernel::devices::storage::management::init();
+  }
+
+  auto storage_boot_module_fixture::setup_modules_from_img(std::vector<std::string> const & module_names,
+                                                           std::vector<std::filesystem::path> const & img_paths) -> void
+  {
+    m_module_names.clear();
+    m_module_data.clear();
+    m_registry = {};
+
+    if (module_names.size() != img_paths.size())
+    {
+      throw std::invalid_argument{"Module names and image paths vectors must have the same size."};
+    }
+
+    for (size_t i = 0; i < module_names.size(); ++i)
+    {
+      setup_module_from_img(module_names[i], img_paths[i]);
+    }
+
+    kapi::boot_modules::set_boot_module_registry(m_registry);
+    kernel::devices::storage::management::init();
+  }
+
+  auto storage_boot_module_fixture::setup_module_from_img(std::string const & module_name,
+                                                          std::filesystem::path const & img_path) -> void
+  {
+    m_module_names.push_back(module_name);
+    auto & mapped_image = m_mapped_images.emplace_back(img_path);
+
+    m_registry.add_boot_module(kapi::boot_modules::boot_module{
+      m_module_names.back().c_str(), kapi::memory::linear_address{mapped_image.mapping}, mapped_image.size});
+  }
+}  // namespace kernel::tests::filesystem
\ No newline at end of file
diff --git a/kernel/src/test_support/filesystem/storage_boot_module_vfs_fixture.cpp b/kernel/src/test_support/filesystem/storage_boot_module_vfs_fixture.cpp
new file mode 100644
index 0000000..02ccfec
--- /dev/null
+++ b/kernel/src/test_support/filesystem/storage_boot_module_vfs_fixture.cpp
@@ -0,0 +1,31 @@
+#include <kernel/test_support/filesystem/storage_boot_module_vfs_fixture.hpp>
+
+#include <kernel/filesystem/vfs.hpp>
+#include <kernel/test_support/filesystem/vfs.hpp>
+
+#include <cstddef>
+#include <filesystem>
+#include <string>
+#include <vector>
+
+namespace kernel::tests::filesystem
+{
+  storage_boot_module_vfs_fixture::~storage_boot_module_vfs_fixture()
+  {
+    kernel::tests::filesystem::vfs::deinit();
+  }
+
+  auto storage_boot_module_vfs_fixture::setup_modules_and_init_vfs(std::size_t module_count, std::size_t module_size)
+      -> void
+  {
+    setup_modules(module_count, module_size);
+    kernel::filesystem::vfs::init();
+  }
+
+  auto storage_boot_module_vfs_fixture::setup_modules_from_img_and_init_vfs(
+      std::vector<std::string> const & module_names, std::vector<std::filesystem::path> const & img_paths) -> void
+  {
+    setup_modules_from_img(module_names, img_paths);
+    kernel::filesystem::vfs::init();
+  }
+}  // namespace kernel::tests::filesystem
\ No newline at end of file
diff --git a/kernel/src/test_support/filesystem/test_assets/README.md b/kernel/src/test_support/filesystem/test_assets/README.md
new file mode 120000
index 0000000..718a227
--- /dev/null
+++ b/kernel/src/test_support/filesystem/test_assets/README.md
@@ -0,0 +1 @@
+/arch/x86_64/support/modules/README.md
\ No newline at end of file
diff --git a/kernel/src/test_support/filesystem/test_assets/ext2_1KB_fs.img b/kernel/src/test_support/filesystem/test_assets/ext2_1KB_fs.img
new file mode 100644
index 0000000..a5202ca
--- /dev/null
+++ b/kernel/src/test_support/filesystem/test_assets/ext2_1KB_fs.img
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:98ac3c1be872806e25fb14eea168ca79a91959f4e6a5ac3d00c5d8224c1f73a3
+size 10485760
diff --git a/kernel/src/test_support/filesystem/test_assets/ext2_2KB_fs.img b/kernel/src/test_support/filesystem/test_assets/ext2_2KB_fs.img
new file mode 100644
index 0000000..7f297f0
--- /dev/null
+++ b/kernel/src/test_support/filesystem/test_assets/ext2_2KB_fs.img
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:6d9e872916e7d9107b321cc007e151899d5f19400a694666c0b24d482aef61ca
+size 5242880
diff --git a/kernel/src/test_support/filesystem/test_assets/ext2_4KB_fs.img b/kernel/src/test_support/filesystem/test_assets/ext2_4KB_fs.img
new file mode 100644
index 0000000..c3f6daf
--- /dev/null
+++ b/kernel/src/test_support/filesystem/test_assets/ext2_4KB_fs.img
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:026ca30269dbd80beb2dd74677c94676d1d4a7f6b5fe406c4ddb82836ba2dc00
+size 10485760
diff --git a/kernel/src/test_support/kapi/cio.cpp b/kernel/src/test_support/kapi/cio.cpp
new file mode 100644
index 0000000..98bc99d
--- /dev/null
+++ b/kernel/src/test_support/kapi/cio.cpp
@@ -0,0 +1,54 @@
+#include <kernel/test_support/cio.hpp>
+
+#include <kernel/test_support/log_buffer.hpp>
+
+#include <kapi/cio.hpp>
+
+#include <atomic>
+#include <optional>
+#include <stdexcept>
+
+namespace
+{
+
+  auto constinit is_initialized = std::atomic_flag{};
+  auto constinit device = std::optional<kernel::tests::cio::output_device>{};
+
+}  // namespace
+
+namespace kapi::cio
+{
+
+  auto init() -> void
+  {
+    if (is_initialized.test_and_set())
+    {
+      throw std::logic_error("kapi::cio::init() called more than once");
+    }
+
+    device.emplace();
+    set_output_device(*device);
+  }
+
+}  // namespace kapi::cio
+
+namespace kernel::tests::cio
+{
+
+  auto deinit() -> void
+  {
+    if (!is_initialized.test())
+    {
+      throw std::logic_error("kapi::cio::deinit() called before kapi::cio::init()");
+    }
+
+    device.reset();
+    is_initialized.clear();
+  }
+
+  auto log_buffer() -> kernel::tests::log_buffer &
+  {
+    return device->log_buffer();
+  }
+
+}  // namespace kernel::tests::cio
\ No newline at end of file
diff --git a/kernel/src/test_support/kapi/cpu.cpp b/kernel/src/test_support/kapi/cpu.cpp
new file mode 100644
index 0000000..5d95633
--- /dev/null
+++ b/kernel/src/test_support/kapi/cpu.cpp
@@ -0,0 +1,52 @@
+#include <kernel/test_support/cpu.hpp>
+
+#include <kapi/cpu.hpp>
+
+#include <atomic>
+#include <stdexcept>
+
+namespace
+{
+  auto static initialized = std::atomic_flag{};
+}
+
+namespace kapi::cpu
+{
+
+  auto init() -> void
+  {
+    if (initialized.test_and_set())
+    {
+      throw std::logic_error("kapi::cpu::init() called more than once");
+    }
+
+    // TODO: make sure that simulated interrupt can run.
+  }
+
+  auto halt() -> void
+  {
+    throw kernel::tests::cpu::halt{};
+  }
+
+  auto discover_topology() -> bool
+  {
+    // TODO: implement more meaningful simulated CPU topology discovery
+    return true;
+  }
+
+}  // namespace kapi::cpu
+
+namespace kernel::tests::cpu
+{
+
+  auto deinit() -> void
+  {
+    if (!initialized.test())
+    {
+      throw std::logic_error{"kapi::cpu::reset() called before kapi::cpu::init()"};
+    }
+
+    initialized.clear();
+  }
+
+}  // namespace kernel::tests::cpu
\ No newline at end of file
diff --git a/kernel/src/test_support/kapi/interrupts.cpp b/kernel/src/test_support/kapi/interrupts.cpp
new file mode 100644
index 0000000..0077266
--- /dev/null
+++ b/kernel/src/test_support/kapi/interrupts.cpp
@@ -0,0 +1,11 @@
+#include <kapi/interrupts.hpp>
+
+namespace kapi::interrupts
+{
+
+  auto enable() -> void
+  {
+    // TODO: enable simulated interrupts.
+  }
+
+}  // namespace kapi::interrupts
\ No newline at end of file
diff --git a/kernel/src/test_support/kapi/memory.cpp b/kernel/src/test_support/kapi/memory.cpp
new file mode 100644
index 0000000..7fc95cb
--- /dev/null
+++ b/kernel/src/test_support/kapi/memory.cpp
@@ -0,0 +1,74 @@
+#include <kapi/memory.hpp>
+
+#include <kernel/test_support/bump_frame_allocator.hpp>
+#include <kernel/test_support/page_mapper.hpp>
+
+#include <kapi/memory.hpp>
+
+#include <kstd/units>
+
+#include <optional>
+
+namespace
+{
+  //! The size of the simulated RAM.
+  constexpr auto physical_size = kstd::units::MiB(32);
+  constexpr auto virtual_size = kstd::units::GiB(1);
+
+  constexpr auto number_of_frames = physical_size / kapi::memory::frame::size;
+
+  auto constinit bump_allocator = std::optional<kernel::tests::bump_frame_allocator>{};
+  auto constinit test_mapper = std::optional<kernel::tests::page_mapper>{};
+
+  auto constinit old_allocator = std::optional<kapi::memory::frame_allocator *>{};
+  auto constinit old_mapper = std::optional<kapi::memory::page_mapper *>{};
+
+  auto handoff_to_kernel_pmm(kapi::memory::frame_allocator & new_allocator) -> void
+  {
+    auto first_free_frame = bump_allocator->next_free_frame;
+    auto number_of_free_frames = number_of_frames - first_free_frame;
+    new_allocator.release_many({kapi::memory::frame{first_free_frame}, number_of_free_frames});
+  }
+
+}  // namespace
+
+namespace kapi::memory
+{
+
+  auto init() -> void
+  {
+    bump_allocator.emplace();
+    test_mapper.emplace(physical_size, virtual_size);
+
+    old_allocator = set_frame_allocator(*bump_allocator);
+    old_mapper = set_page_mapper(*test_mapper);
+
+    init_pmm(physical_size / frame::size, handoff_to_kernel_pmm);
+  }
+}  // namespace kapi::memory
+
+namespace kernel::tests::memory
+{
+
+  auto deinit() -> void
+  {
+    if (old_allocator && *old_allocator)
+    {
+      set_frame_allocator(**old_allocator);
+    }
+
+    if (old_mapper && *old_mapper)
+    {
+      set_page_mapper(**old_mapper);
+    }
+
+    bump_allocator.reset();
+    test_mapper.reset();
+  }
+
+  auto virtual_base() -> kapi::memory::linear_address
+  {
+    return test_mapper->memory.virtual_base();
+  }
+
+}  // namespace kernel::tests::memory
\ No newline at end of file
diff --git a/kernel/src/test_support/log_buffer.cpp b/kernel/src/test_support/log_buffer.cpp
new file mode 100644
index 0000000..04d875b
--- /dev/null
+++ b/kernel/src/test_support/log_buffer.cpp
@@ -0,0 +1,33 @@
+#include <kernel/test_support/log_buffer.hpp>
+
+#include <algorithm>
+#include <string>
+#include <vector>
+
+namespace kernel::tests
+{
+
+  auto log_buffer::append(std::string const & message) -> void
+  {
+    m_messages.push_back(message);
+  }
+
+  auto log_buffer::clear() -> void
+  {
+    m_messages.clear();
+  }
+
+  auto log_buffer::flat_messages() -> std::string
+  {
+    return std::ranges::fold_left(m_messages, std::string{}, [](std::string accumulator, std::string const & message) {
+      accumulator += message;
+      return accumulator;
+    });
+  }
+
+  auto log_buffer::messages() -> std::vector<std::string> const &
+  {
+    return m_messages;
+  }
+
+}  // namespace kernel::tests
diff --git a/kernel/src/test_support/output_device.cpp b/kernel/src/test_support/output_device.cpp
new file mode 100644
index 0000000..45fb4bc
--- /dev/null
+++ b/kernel/src/test_support/output_device.cpp
@@ -0,0 +1,28 @@
+#include <kernel/test_support/cio.hpp>
+#include <kernel/test_support/log_buffer.hpp>
+
+#include <kapi/cio.hpp>
+
+#include <iostream>
+#include <string>
+#include <string_view>
+
+namespace kernel::tests::cio
+{
+
+  auto output_device::write(kapi::cio::output_stream stream, std::string_view text) -> void
+  {
+    auto & standard_stream = stream == kapi::cio::output_stream::stdout ? std::cout : std::cerr;
+    standard_stream << text;
+    if (text != "\n")
+    {
+      m_log_buffer.append(std::string{text});
+    }
+  }
+
+  auto output_device::log_buffer() noexcept -> kernel::tests::log_buffer &
+  {
+    return m_log_buffer;
+  }
+
+}  // namespace kernel::tests::cio
\ No newline at end of file
diff --git a/kernel/src/test_support/page_mapper.cpp b/kernel/src/test_support/page_mapper.cpp
new file mode 100644
index 0000000..3d50ff1
--- /dev/null
+++ b/kernel/src/test_support/page_mapper.cpp
@@ -0,0 +1,70 @@
+#include <kernel/test_support/page_mapper.hpp>
+
+#include <kapi/memory.hpp>
+
+#include <kstd/units>
+
+#include <cstddef>
+#include <format>
+#include <stdexcept>
+
+namespace kernel::tests
+{
+
+  page_mapper::page_mapper(kstd::units::bytes physical_size, kstd::units::bytes virtual_size)
+      : memory{physical_size, virtual_size}
+  {}
+
+  auto page_mapper::map(kapi::memory::page page, kapi::memory::frame frame, flags) -> std::byte *
+  {
+    auto result = page_mappings.insert({page.number(), frame});
+    if (!result.second)
+    {
+      auto error = std::format("Page {} was already mapped!", page.number());
+      throw std::invalid_argument{error};
+    }
+
+    auto page_address = page.start_address();
+    auto virtual_base = memory.virtual_base();
+    auto virtual_end = virtual_base + memory.virtual_size();
+
+    if (page_address >= virtual_base && page_address < virtual_end)
+    {
+      auto virtual_target = static_cast<std::byte *>(page_address);
+      auto physical_offset = frame.number() * kapi::memory::frame::size;
+      return memory.map(kapi::memory::page::size, virtual_target, physical_offset.value);
+    }
+    else if (page_address >= kapi::memory::mmio_base)
+    {
+      throw std::runtime_error("MMIO mapping not yet supported in testing!");
+    }
+    else if (page_address >= kapi::memory::higher_half_direct_map_base)
+    {
+      auto offset = frame.number() * kapi::memory::frame::size;
+      return memory.physical_base() + offset;
+    }
+
+    return nullptr;
+  }
+
+  auto page_mapper::unmap(kapi::memory::page page) -> void
+  {
+    if (!try_unmap(page))
+    {
+      auto error = std::format("Page {} was never mapped!", page.number());
+      throw std::invalid_argument{error};
+    }
+  }
+
+  auto page_mapper::try_unmap(kapi::memory::page page) noexcept -> bool
+  {
+    if (page_mappings.contains(page.number()))
+    {
+      page_mappings.erase(page.number());
+      return true;
+    }
+
+    return false;
+  }
+
+}  // namespace kernel::tests
\ No newline at end of file
diff --git a/kernel/src/test_support/simulated_memory.cpp b/kernel/src/test_support/simulated_memory.cpp
new file mode 100644
index 0000000..074e6b1
--- /dev/null
+++ b/kernel/src/test_support/simulated_memory.cpp
@@ -0,0 +1,106 @@
+#include <kernel/test_support/simulated_memory.hpp>
+
+#include <kapi/memory.hpp>
+
+#include <kstd/units>
+
+#include <cerrno>
+#include <cstddef>
+#include <cstring>
+#include <format>
+#include <stdexcept>
+#include <unistd.h>
+
+#include <sys/mman.h>
+#include <sys/types.h>
+
+namespace kernel::tests
+{
+
+  simulated_memory::simulated_memory(kstd::units::bytes physical_size, kstd::units::bytes virtual_size)
+      : m_descriptor{memfd_create("teachos_simulated_memory", 0)}
+      , m_physical_size{physical_size}
+      , m_virtual_size{virtual_size}
+  {
+    if (m_descriptor < 0)
+    {
+      auto error = std::format("Failed to allocate backing memory: {}", strerror(errno));
+      throw std::runtime_error(error);
+    }
+
+    if (ftruncate(m_descriptor, static_cast<off_t>(m_physical_size.value)) < 0)
+    {
+      auto error = std::format("Failed to reserve backing memory: {}", strerror(errno));
+      throw std::runtime_error(error);
+    }
+
+    auto physical_storage = mmap(nullptr, m_physical_size.value, PROT_READ | PROT_WRITE, MAP_SHARED, m_descriptor, 0);
+    if (physical_storage == MAP_FAILED)
+    {
+      auto error = std::format("Failed to map backing memory: {}", strerror(errno));
+      throw std::runtime_error(error);
+    }
+
+    auto virtual_pointer = mmap(nullptr, virtual_size.value, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    if (virtual_pointer == MAP_FAILED)
+    {
+      auto error = std::format("Failed to reserve virtual memory: {}", strerror(errno));
+      throw std::runtime_error(error);
+    }
+
+    m_physical_base = static_cast<std::byte *>(physical_storage);
+    m_virtual_base = static_cast<std::byte *>(virtual_pointer);
+
+    clear();
+  }
+
+  simulated_memory::~simulated_memory()
+  {
+    munmap(m_virtual_base, m_virtual_size.value);
+    munmap(m_physical_base, m_physical_size.value);
+    close(m_descriptor);
+  }
+
+  auto simulated_memory::clear() -> void
+  {
+    std::memset(m_physical_base, 0, m_physical_size.value);
+  }
+
+  auto simulated_memory::physical_base() noexcept -> std::byte *
+  {
+    return m_physical_base;
+  }
+
+  auto simulated_memory::physical_base() const noexcept -> std::byte const *
+  {
+    return m_physical_base;
+  }
+
+  auto simulated_memory::physical_size() const noexcept -> kstd::units::bytes
+  {
+    return m_physical_size;
+  }
+
+  auto simulated_memory::virtual_base() const noexcept -> kapi::memory::linear_address
+  {
+    return kapi::memory::linear_address{m_virtual_base};
+  }
+
+  auto simulated_memory::virtual_size() const noexcept -> kstd::units::bytes
+  {
+    return m_virtual_size;
+  }
+
+  auto simulated_memory::map(kstd::units::bytes size, std::byte * to, off_t offset) -> std::byte *
+  {
+    auto mapped_ptr = mmap(to, size.value, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, m_descriptor, offset);
+    if (mapped_ptr == MAP_FAILED)
+    {
+      auto error = std::format("Failed to map page: {}", strerror(errno));
+      throw std::runtime_error(error);
+    }
+
+    return static_cast<std::byte *>(mapped_ptr);
+  }
+
+}  // namespace kernel::tests
\ No newline at end of file
diff --git a/kernel/src/test_support/state_reset_listener.cpp b/kernel/src/test_support/state_reset_listener.cpp
new file mode 100644
index 0000000..6bb7537
--- /dev/null
+++ b/kernel/src/test_support/state_reset_listener.cpp
@@ -0,0 +1,48 @@
+#include <kernel/filesystem/open_file_table.hpp>
+#include <kernel/test_support/boot_modules.hpp>
+#include <kernel/test_support/cio.hpp>
+#include <kernel/test_support/cpu.hpp>
+#include <kernel/test_support/devices/storage/management.hpp>
+#include <kernel/test_support/filesystem/open_file_table.hpp>
+#include <kernel/test_support/filesystem/vfs.hpp>
+#include <kernel/test_support/memory.hpp>
+
+#include <kapi/cio.hpp>
+#include <kapi/cpu.hpp>
+#include <kapi/memory.hpp>
+
+#include <catch2/catch_test_case_info.hpp>
+#include <catch2/interfaces/catch_interfaces_reporter.hpp>
+#include <catch2/reporters/catch_reporter_event_listener.hpp>
+#include <catch2/reporters/catch_reporter_registrars.hpp>
+
+struct state_reset_listener : Catch::EventListenerBase
+{
+  using EventListenerBase::EventListenerBase;
+
+  void testCaseStarting(Catch::TestCaseInfo const &) override
+  {
+    kernel::filesystem::open_file_table::init();
+
+    kapi::cio::init();
+    kapi::cpu::init();
+    kapi::memory::init();
+  }
+
+  void testCaseEnded(Catch::TestCaseStats const &) override
+  {
+    kernel::tests::filesystem::open_file_table::deinit();
+    kernel::tests::filesystem::vfs::deinit();
+    kernel::tests::boot_modules::deinit();
+    kernel::tests::devices::storage::management::deinit();
+
+    kernel::tests::memory::deinit();
+    kernel::tests::cpu::deinit();
+    kernel::tests::cio::deinit();
+  }
+};
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpedantic"
+CATCH_REGISTER_LISTENER(state_reset_listener);
+#pragma GCC diagnostic pop
\ No newline at end of file