Revert "update long jump handling"

This reverts commit 9ddfcd02413a93718e8cde53f9ba5a96a5b29b8f.

5 files changed, 19 insertions, 20 deletions

diff --git a/.vscode/launch.json b/.vscode/launch.json
index e6af5d0..ebcd01a 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -24,12 +24,7 @@
                 {
                     "description": "Set breakpoint on _start",
                     "text": "-break-insert _start"
-                },
-                {
-                    "description": "Set breakpoint on reload_segment_register_trampoline",
-                    "text": "-break-insert reload_segment_register_trampoline"
                 }
-
             ]
         }
     ],
diff --git a/arch/x86_64/include/arch/boot/pointers.hpp b/arch/x86_64/include/arch/boot/pointers.hpp
index 5092fa6..5bcb792 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" auto reload_segment_register_trampoline() -> void;
+  extern "C" size_t const segment_register_reload_pointer;
 
 }  // namespace teachos::arch::boot
 
diff --git a/arch/x86_64/src/boot/boot.s b/arch/x86_64/src/boot/boot.s
index f6c7978..35a6121 100644
--- a/arch/x86_64/src/boot/boot.s
+++ b/arch/x86_64/src/boot/boot.s
@@ -354,11 +354,8 @@ prepare_page_maps:
 .section .boot_text, "ax", @progbits
 .code64
 
-.global reload_segment_register_trampoline
-reload_segment_register_trampoline:
-    jmp 0x08, $_reload_cs
-
-_reload_cs:
+.global segment_register_reload_pointer
+segment_register_reload_pointer:
     xor %rax, %rax
     mov %rax, %ss
     mov %rax, %ds
@@ -369,7 +366,14 @@ _reload_cs:
     ret
 
 _transition_to_long_mode:
-    call _reload_cs
+    //call segment_register_reload_pointer
+
+    xor %rax, %rax
+    mov %rax, %ss
+    mov %rax, %ds
+    mov %rax, %es
+    mov %rax, %fs
+    mov %rax, %gs
 
     movl $0xb8000, (vga_buffer_pointer)
 
diff --git a/arch/x86_64/src/context_switching/main.cpp b/arch/x86_64/src/context_switching/main.cpp
index 1417a25..c3c0cf0 100644
--- a/arch/x86_64/src/context_switching/main.cpp
+++ b/arch/x86_64/src/context_switching/main.cpp
@@ -13,8 +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();
 
-    // Execute trampoline function for the GDT loading long jump
-    boot::reload_segment_register_trampoline();
+    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/jmp.cpp b/arch/x86_64/src/kernel/cpu/jmp.cpp
index 78b65f4..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(far_pointer pointer) -> void
-  // {
-  //   asm volatile("ljmp $[segment_selector],$[address]"
-  //                : /* no output from call */
-  //                : [segment_selector] "m"(pointer.selector), [address] "m"(pointer.offset));
-  // }
+  auto jmp(far_pointer pointer) -> void
+  {
+    asm volatile("jmp *%[input]" : /* no output from call */ : [input] "m"(pointer));
+  }
 }  // namespace teachos::arch::kernel::cpu