Merge branch 'fmorgner/patch-context-switching' into 'feat_inital_context_switching'

Fix GDT and CS reload

See merge request teachos/kernel!5

4 files changed, 18 insertions, 12 deletions

diff --git a/arch/x86_64/include/arch/boot/pointers.hpp b/arch/x86_64/include/arch/boot/pointers.hpp
index c08de52..9bf5cfd 100644
--- a/arch/x86_64/include/arch/boot/pointers.hpp
+++ b/arch/x86_64/include/arch/boot/pointers.hpp
@@ -13,7 +13,7 @@ namespace teachos::arch::boot
   /**
    * @brief Address pointing to the method that clears all segment registers.
    */
-  extern "C" size_t reload_segment_register;
+  extern "C" void reload_segment_register();
 
 }  // namespace teachos::arch::boot
 
diff --git a/arch/x86_64/include/arch/context_switching/segment_descriptor_table/gdt_flags.hpp b/arch/x86_64/include/arch/context_switching/segment_descriptor_table/gdt_flags.hpp
index fdf0044..764aec5 100644
--- a/arch/x86_64/include/arch/context_switching/segment_descriptor_table/gdt_flags.hpp
+++ b/arch/x86_64/include/arch/context_switching/segment_descriptor_table/gdt_flags.hpp
@@ -18,17 +18,24 @@ namespace teachos::arch::context_switching::segment_descriptor_table
      */
     enum bitset : uint8_t
     {
-      LENGTH = 1U << 0U,  ///< Defines in IA-32e mode (64-bit code and 32-bit compatability mode) if the segment
-                          ///< contains 64-bit code. Otherwise this bit should always be 0. Enable if instructions are
-                          ///< executed in 64-bit code, otherwise they are executed in compatability 32-bit mode. If bis
-                          ///< is set the DEFAULT_LENGTH bis needs to be 0
+      LONG_MODE = 1U << 1U,  ///< Defines in IA-32e mode (64-bit code and 32-bit compatability mode) if the segment
+                             ///< contains 64-bit code. Otherwise this bit should always be 0. Enable if instructions are
+                             ///< executed in 64-bit code, otherwise they are executed in compatability 32-bit mode. If bis
+                             ///< is set the DEFAULT_LENGTH bis needs to be 0
+
+      // FIXME: Where does this come from, and is this value correct?
       UPPER_BOUND = 1U << 1U,  ///< Specifies the upper bound of the segment for expand down data segment. Enable for 5
                                ///< GiB, 4 KiB otherwise.
+
+      // FIXME: Where does this come from, and is this value correct?
       STACK_POINTER_SIZE = 1U << 1U,  ///< Specifies the size of the Stack Pointer (SP) for stack segments used for
                                       ///< implicit stack operations. Enable for 32 bit, 16 bit otherwise.
+
+      // FIXME: Where does this come from, and is this value correct?
       DEFAULT_LENGTH = 1U << 1U,      ///< Indicates the default length for code segments with effective addresses and
                                       ///< operands. Enable for 32 bit, 16 bit otherwise.
-      GRANULARITY = 1U << 2U,  ///< Indicates the size the Limit value in the segment descriptor is scaled by 1 Byte
+
+      GRANULARITY = 1U << 3U,  ///< Indicates the size the Limit value in the segment descriptor is scaled by 1 Byte
                                ///< blocks if the bit is not set or by 4 KiB blocks if the bit is set.
     };
 
diff --git a/arch/x86_64/include/arch/context_switching/segment_descriptor_table/global_descriptor_table_pointer.hpp b/arch/x86_64/include/arch/context_switching/segment_descriptor_table/global_descriptor_table_pointer.hpp
index 13d6f53..6fac2a0 100644
--- a/arch/x86_64/include/arch/context_switching/segment_descriptor_table/global_descriptor_table_pointer.hpp
+++ b/arch/x86_64/include/arch/context_switching/segment_descriptor_table/global_descriptor_table_pointer.hpp
@@ -26,7 +26,7 @@ namespace teachos::arch::context_switching::segment_descriptor_table
     /**
      * @brief Constructor.
      */
-    global_descriptor_table_pointer(uint16_t table_length, global_descriptor_table * address);
+    global_descriptor_table_pointer(uint16_t table_length, segment_descriptor * address);
 
     /**
      * @brief Defaulted three-way comparsion operator.
@@ -35,7 +35,7 @@ namespace teachos::arch::context_switching::segment_descriptor_table
 
   private:
     uint16_t table_length = {};  ///< The amount of segment descriptor entries in the global descriptor table - 1.
-    global_descriptor_table * address = {};  ///< Non-owning pointer to the GDT base address.
+    segment_descriptor * address = {};  ///< Non-owning pointer to the GDT base address.
   };
 }  // namespace teachos::arch::context_switching::segment_descriptor_table
 
diff --git a/arch/x86_64/include/arch/kernel/cpu/jmp.hpp b/arch/x86_64/include/arch/kernel/cpu/jmp.hpp
index 163fac6..0ed38e9 100644
--- a/arch/x86_64/include/arch/kernel/cpu/jmp.hpp
+++ b/arch/x86_64/include/arch/kernel/cpu/jmp.hpp
@@ -10,11 +10,10 @@ namespace teachos::arch::kernel::cpu
   /**
    * @brief Far jump - A jump to an instruction located in a different segment.
    */
-  struct [[gnu::packed]] far_pointer
+  struct far_pointer
   {
-    std::size_t function;  ///< Address of the function we want to jump too. (0- 63)
-    context_switching::interrupt_descriptor_table::segment_selector
-        selector;  ///< Segment selector that shows the segment we want to jump into. (64 - 79)
+    void (*function)();  ///< Address of the function we want to jump too. (0-63)
+    std::uint16_t index; ///< Index of the GDT entry we want to load into register CS. (64-79)
   };
 
   /**