Attempt to fix crash in far jump. WIP does not return from call to assembler method

9 files changed, 37 insertions, 32 deletions

diff --git a/arch/x86_64/include/arch/boot/pointers.hpp b/arch/x86_64/include/arch/boot/pointers.hpp
index 2a43f22..5bcb792 100644
--- a/arch/x86_64/include/arch/boot/pointers.hpp
+++ b/arch/x86_64/include/arch/boot/pointers.hpp
@@ -11,7 +11,7 @@ namespace teachos::arch::boot
   extern "C" size_t const multiboot_information_pointer;
 
   /**
-   * @brief Address pointing to the start of the multiboot information structure.
+   * @brief Address pointing to the method that clears all segment registers.
    */
   extern "C" size_t const segment_register_reload_pointer;
 
diff --git a/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/segment_selector.hpp b/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/segment_selector.hpp
index c31e2d0..73cd176 100644
--- a/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/segment_selector.hpp
+++ b/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/segment_selector.hpp
@@ -43,7 +43,8 @@ namespace teachos::arch::context_switching::interrupt_descriptor_table
     /**
      * @brief Constructor.
      *
-     * @param index Index into the local or global descriptor table.
+     * @param index Index into the local or global descriptor table. Processor multiplies the index value by 16 (number
+     * of bytes in segment descriptor) and adds the result to the base address.
      * @param flags Allows to set flags for the flags field using the unscoped enum contained in this class, used to
      * allow for direct integer conversion.
      */
@@ -66,8 +67,10 @@ namespace teachos::arch::context_switching::interrupt_descriptor_table
     auto operator<=>(segment_selector const & other) const -> std::strong_ordering = default;
 
   private:
-    uint8_t _flags : 3 = {};    ///< Underlying bits used to read the flags from.
-    uint16_t _index : 13 = {};  ///< Index into the local or global descriptor table.
+    uint8_t _flags : 3 = {};  ///< Underlying bits used to read the flags from.
+    uint16_t _index : 13 =
+        {};  ///< Index into the local or global descriptor table. Processor multiplies the index value by 16 (number of
+             ///< bytes in segment descriptor) and adds the result to the base address.
   };
 }  // namespace teachos::arch::context_switching::interrupt_descriptor_table
 
diff --git a/arch/x86_64/include/arch/kernel/cpu/if.hpp b/arch/x86_64/include/arch/kernel/cpu/if.hpp
index 51f5d9a..48707dc 100644
--- a/arch/x86_64/include/arch/kernel/cpu/if.hpp
+++ b/arch/x86_64/include/arch/kernel/cpu/if.hpp
@@ -9,6 +9,13 @@ namespace teachos::arch::kernel::cpu
    */
   auto set_interrupt_flag() -> void;
 
+  /**
+   * @brief Clears the interrupt flag (IF) in the EFLAGS register.
+   * This will stop the processor to respond to maskable hardware interrupts and needs to be done before changing the
+   * Interrupt Descriptor Table with lidt.
+   */
+  auto clear_interrupt_flag() -> void;
+
 }  // namespace teachos::arch::kernel::cpu
 
 #endif  // TEACHOS_ARCH_X86_64_KERNEL_CPU_IF_HPP
diff --git a/arch/x86_64/include/arch/kernel/cpu/jmp.hpp b/arch/x86_64/include/arch/kernel/cpu/jmp.hpp
index 666174c..5bc7d07 100644
--- a/arch/x86_64/include/arch/kernel/cpu/jmp.hpp
+++ b/arch/x86_64/include/arch/kernel/cpu/jmp.hpp
@@ -1,6 +1,8 @@
 #ifndef TEACHOS_ARCH_X86_64_KERNEL_CPU_JMP_HPP
 #define TEACHOS_ARCH_X86_64_KERNEL_CPU_JMP_HPP
 
+#include "arch/context_switching/interrupt_descriptor_table/segment_selector.hpp"
+
 #include <cstdint>
 
 namespace teachos::arch::kernel::cpu
@@ -10,14 +12,15 @@ namespace teachos::arch::kernel::cpu
    */
   struct [[gnu::packed]] far_pointer
   {
-    uint64_t offset;   ///< Selector of the segment in which the jump occurs.
-    uint16_t segment;  ///< Address to jump to within the segment.
+    uint64_t offset;  ///< Selector of the segment in which the jump occurs. (0- 63)
+    context_switching::interrupt_descriptor_table::segment_selector
+        selector;  ///< Address to jump to within the segment. (64 - 79)
   };
 
   /**
    * @brief Near jump - A jump to an instruction within the current code segment.
    *
-   * @param address to jump to.
+   * @param address Address  we want to jump to.
    */
   auto jmp(uint64_t address) -> void;
 
@@ -25,10 +28,9 @@ namespace teachos::arch::kernel::cpu
    * @brief Far jump - A jump to an instruction located in a different segment than the current code segment but at the
    * same privilege level.
    *
-   * @param segment in which the jump occurs.
-   * @param offset to jump to.
+   * @param pointer 64-bit operand size far pointer that we should jump too.
    */
-  auto jmp(uint64_t segment, uint64_t offset) -> void;
+  auto jmp(far_pointer pointer) -> void;
 
 }  // namespace teachos::arch::kernel::cpu
 
diff --git a/arch/x86_64/src/boot/boot.s b/arch/x86_64/src/boot/boot.s
index 4fb23e5..35a6121 100644
--- a/arch/x86_64/src/boot/boot.s
+++ b/arch/x86_64/src/boot/boot.s
@@ -366,7 +366,7 @@ segment_register_reload_pointer:
     ret
 
 _transition_to_long_mode:
-    call segment_register_reload_pointer
+    //call segment_register_reload_pointer
 
     xor %rax, %rax
     mov %rax, %ss
diff --git a/arch/x86_64/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.cpp b/arch/x86_64/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.cpp
index 0555e4c..ddc098e 100644
--- a/arch/x86_64/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.cpp
+++ b/arch/x86_64/src/context_switching/interrupt_descriptor_table/interrupt_descriptor_table.cpp
@@ -9,22 +9,12 @@ namespace teachos::arch::context_switching::interrupt_descriptor_table
   {
     auto create_interrupt_descriptor_table() -> interrupt_descriptor_table
     {
-      interrupt_descriptor_table idt{};
-
-      // Define basic exception handlers (at least for CPU exceptions 0x00-0x1F)
-      for (uint8_t vector = 0; vector < 32; ++vector)
-      {
-        uint64_t offset = reinterpret_cast<uint64_t>(default_exception_handler);  // Use a real handler function
-        segment_selector selector{0U, segment_selector::REQUEST_LEVEL_KERNEL};
-        ist_offset ist{0U};  // Default stack offset (can be updated for IST)
-        idt_flags flags{idt_flags::DESCRIPTOR_LEVEL_KERNEL | idt_flags::TRAP_GATE};
-
-        idt.push_back(gate_descriptor{selector, ist, flags, offset});
-      }
-
-      // Additional entries for hardware interrupts (IRQs) and syscalls can be added here
-
-      return idt;
+      uint64_t offset = 0U;
+      segment_selector selector{0U, segment_selector::REQUEST_LEVEL_KERNEL};
+      ist_offset ist{0U};
+      idt_flags flags{idt_flags::DESCRIPTOR_LEVEL_KERNEL};
+      gate_descriptor gate_descriptor{selector, ist, flags, offset};
+      return interrupt_descriptor_table{gate_descriptor};
     }
   }  // namespace
 
diff --git a/arch/x86_64/src/context_switching/main.cpp b/arch/x86_64/src/context_switching/main.cpp
index 95a25e0..c3c0cf0 100644
--- a/arch/x86_64/src/context_switching/main.cpp
+++ b/arch/x86_64/src/context_switching/main.cpp
@@ -13,7 +13,10 @@ namespace teachos::arch::context_switching
     decltype(auto) global_descriptor_table = segment_descriptor_table::initialize_global_descriptor_table();
     decltype(auto) interrupt_descriptor_table = interrupt_descriptor_table::initialize_interrupt_descriptor_table();
 
-    kernel::cpu::jmp((uint64_t)&global_descriptor_table.at(1), boot::segment_register_reload_pointer);
+    interrupt_descriptor_table::segment_selector segment_selector{
+        1U, interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_KERNEL};
+    kernel::cpu::far_pointer pointer{boot::segment_register_reload_pointer, segment_selector};
+    kernel::cpu::jmp(pointer);
 
     // Load task state segment descriptor from the last element in the global descriptor table, done by calculating
     // offset in bytes to the start of the segment descriptor (5 * 16) = 80
diff --git a/arch/x86_64/src/kernel/cpu/if.cpp b/arch/x86_64/src/kernel/cpu/if.cpp
index 2a25df5..60a90a3 100644
--- a/arch/x86_64/src/kernel/cpu/if.cpp
+++ b/arch/x86_64/src/kernel/cpu/if.cpp
@@ -2,4 +2,6 @@ namespace teachos::arch::kernel::cpu
 {
   auto set_interrupt_flag() -> void { asm volatile("sti"); }
 
+  auto clear_interrupt_flag() -> void { asm volatile("cli"); }
+
 }  // namespace teachos::arch::kernel::cpu
diff --git a/arch/x86_64/src/kernel/cpu/jmp.cpp b/arch/x86_64/src/kernel/cpu/jmp.cpp
index 009981b..205c4a9 100644
--- a/arch/x86_64/src/kernel/cpu/jmp.cpp
+++ b/arch/x86_64/src/kernel/cpu/jmp.cpp
@@ -7,10 +7,8 @@ namespace teachos::arch::kernel::cpu
     asm volatile("jmp *%[input]" : /* no output from call */ : [input] "r"(address));
   }
 
-  auto jmp(uint64_t segment, uint64_t offset) -> void
+  auto jmp(far_pointer pointer) -> void
   {
-    far_pointer far_pointer = {offset, static_cast<uint16_t>(segment)};
-    asm volatile("jmp *%0" : : "m"(far_pointer));
+    asm volatile("jmp *%[input]" : /* no output from call */ : [input] "m"(pointer));
   }
-
 }  // namespace teachos::arch::kernel::cpu