1 files changed, 164 insertions, 0 deletions
diff --git a/arch/x86_64/arch/cpu/initialization.cpp b/arch/x86_64/arch/cpu/initialization.cpp
new file mode 100644
index 0000000..1be9c82
--- /dev/null
+++ b/arch/x86_64/arch/cpu/initialization.cpp
@@ -0,0 +1,164 @@
+#include <arch/cpu/initialization.hpp>
+
+#include <arch/cpu/global_descriptor_table.hpp>
+#include <arch/cpu/interrupts.hpp>
+#include <arch/cpu/legacy_pic.hpp>
+#include <arch/cpu/segment_descriptor.hpp>
+#include <arch/cpu/task_state_segment.hpp>
+
+#include <kstd/print>
+
+#include <bit>
+#include <cstdint>
+
+namespace arch::cpu
+{
+
+  namespace
+  {
+    constexpr auto gdt_null_descriptor = segment_descriptor{};
+
+    constexpr auto gdt_kernel_code_descriptor = segment_descriptor{
+      .limit_low = 0xffff,
+      .base_low = 0,
+      .accessed = false,
+      .read_write = false,
+      .direction_or_conforming = false,
+      .executable = true,
+      .type = segment_type::code_or_data,
+      .privilege_level = 0,
+      .present = true,
+      .limit_high = 0xf,
+      .long_mode = true,
+      .protected_mode = false,
+      .granularity = segment_granularity::page,
+      .base_high = 0,
+    };
+
+    constexpr auto gdt_kernel_data_descriptor = segment_descriptor{
+      .limit_low = 0xffff,
+      .base_low = 0,
+      .accessed = false,
+      .read_write = true,
+      .direction_or_conforming = false,
+      .executable = false,
+      .type = segment_type::code_or_data,
+      .privilege_level = 0,
+      .present = true,
+      .limit_high = 0xf,
+      .long_mode = false,
+      .protected_mode = true,
+      .granularity = segment_granularity::page,
+      .base_high = 0,
+    };
+
+    constexpr auto gdt_user_code_descriptor = segment_descriptor{
+      .limit_low = 0xffff,
+      .base_low = 0,
+      .accessed = false,
+      .read_write = false,
+      .direction_or_conforming = false,
+      .executable = true,
+      .type = segment_type::code_or_data,
+      .privilege_level = 3,
+      .present = true,
+      .limit_high = 0xf,
+      .long_mode = true,
+      .protected_mode = false,
+      .granularity = segment_granularity::page,
+      .base_high = 0,
+    };
+
+    constexpr auto gdt_user_data_descriptor = segment_descriptor{
+      .limit_low = 0xffff,
+      .base_low = 0,
+      .accessed = false,
+      .read_write = true,
+      .direction_or_conforming = false,
+      .executable = false,
+      .type = segment_type::code_or_data,
+      .privilege_level = 3,
+      .present = true,
+      .limit_high = 0xf,
+      .long_mode = false,
+      .protected_mode = false,
+      .granularity = segment_granularity::page,
+      .base_high = 0,
+    };
+
+    constexpr auto make_tss_descriptor(task_state_segment const * tss_ptr) -> system_segment_descriptor
+    {
+      auto const address = std::bit_cast<std::uintptr_t>(tss_ptr);
+      auto const limit = sizeof(task_state_segment) - 1;
+
+      return system_segment_descriptor{
+        {
+         .limit_low = limit & 0xffff,     // NOLINT(readability-magic-numbers)
+          .base_low = address & 0xffffff,  // NOLINT(readability-magic-numbers)
+          .accessed = false,
+         .read_write = false,
+         .direction_or_conforming = false,
+         .executable = false,
+         .type = segment_type::system,
+         .privilege_level = 0,
+         .present = true,
+         .limit_high = (limit >> 16) & 0xf,  // NOLINT(readability-magic-numbers)
+          .long_mode = false,
+         .protected_mode = false,
+         .granularity = segment_granularity::byte,
+         .base_high = (address >> 24) & 0xff,  // NOLINT(readability-magic-numbers)
+        },
+        (address >> 32) & 0xffff'ffff, // NOLINT(readability-magic-numbers)
+      };
+    }
+  }  // namespace
+
+  auto initialize_descriptors() -> void
+  {
+    auto static tss = task_state_segment{};
+    auto static tss_descriptor = make_tss_descriptor(&tss);
+
+    auto static gdt = global_descriptor_table{
+      gdt_null_descriptor,      gdt_kernel_code_descriptor, gdt_kernel_data_descriptor,
+      gdt_user_code_descriptor, gdt_user_data_descriptor,   tss_descriptor,
+    };
+
+    kstd::println("[x86_64:SYS] Reloading Global Descriptor Table.");
+    gdt.load(1, 2);
+
+    kstd::println("[x86_64:SYS] Initializing Interrupt Descriptor Table.");
+    auto static idt = interrupt_descriptor_table{};
+    idt.load();
+  }
+
+  auto initialize_legacy_interrupts() -> void
+  {
+    constexpr auto pic_init_command = std::uint8_t{0x11};
+    constexpr auto pic_master_offset = std::uint8_t{0x20};
+    constexpr auto pic_slave_offset = std::uint8_t{0x28};
+    constexpr auto pic_cascade_address = std::uint8_t{0x04};
+    constexpr auto pic_cascade_slave_identity = std::uint8_t{0x02};
+    constexpr auto pic_use_8086_mode = std::uint8_t{0x01};
+    constexpr auto pic_master_mask = std::uint8_t{0x00};
+    constexpr auto pic_slave_mask = std::uint8_t{0x00};
+
+    pic_master_control_port::write(pic_init_command);
+    pic_slave_control_port::write(pic_init_command);
+
+    pic_master_data_port::write(pic_master_offset);
+    pic_slave_data_port::write(pic_slave_offset);
+
+    pic_master_data_port::write(pic_cascade_address);
+    pic_slave_data_port::write(pic_cascade_slave_identity);
+
+    pic_master_data_port::write(pic_use_8086_mode);
+    pic_slave_data_port::write(pic_use_8086_mode);
+
+    pic_master_data_port::write(pic_master_mask);
+    pic_slave_data_port::write(pic_slave_mask);
+
+    pic_master_data_port::write(pic_master_mask);
+    pic_slave_data_port::write(pic_slave_mask);
+  }
+
+}  // namespace arch::cpu