2 files changed, 38 insertions, 40 deletions

diff --git a/arch/x86_64/src/context_switching/main.cpp b/arch/x86_64/src/context_switching/main.cpp
index 155d150..f73cb19 100644
--- a/arch/x86_64/src/context_switching/main.cpp
+++ b/arch/x86_64/src/context_switching/main.cpp
@@ -1,7 +1,6 @@
 #include "arch/context_switching/main.hpp"
 
 #include "arch/boot/pointers.hpp"
-#include "arch/context_switching/syscall_handler.hpp"
 #include "arch/exception_handling/assert.hpp"
 #include "arch/kernel/cpu/call.hpp"
 #include "arch/kernel/cpu/control_register.hpp"
@@ -30,6 +29,43 @@ namespace teachos::arch::context_switching
 
     auto reload_global_descriptor_table_register() -> void { kernel::cpu::call(KERNEL_CODE_POINTER); }
 
+    auto user_mode_main() -> void
+    {
+      kernel::cpu::validate_segment_registers(USER_DATA_SEGMENT_SELECTOR, USER_CODE_SEGMENT_SELECTOR);
+
+      video::vga::text::write("Successfully entered user mode!", video::vga::text::common_attributes::green_on_black);
+
+      asm volatile("syscall");
+
+      kernel::cpu::validate_segment_registers(USER_DATA_SEGMENT_SELECTOR, USER_CODE_SEGMENT_SELECTOR);
+
+      video::vga::text::write("Successfully made a SYSCALL and returned back with SYSRET!",
+                              video::vga::text::common_attributes::green_on_black);
+    }
+
+    auto syscall_handler() -> void
+    {
+      uint64_t dummy{};
+      switch (dummy)
+      {
+        case 0:
+          break;
+        default:
+          break;
+      }
+
+      asm volatile("sysretq");
+    }
+
+    auto enable_systemcall() -> void
+    {
+      uint64_t const syscall_function = reinterpret_cast<uint64_t>(syscall_handler);
+      kernel::cpu::write_msr(IA32_LSTAR_ADDRESS, syscall_function);
+      kernel::cpu::write_msr(IA32_FMASK_ADDRESS, 0U);
+      kernel::cpu::write_msr(IA32_STAR_ADDRESS, KERNEL_CODE_SEGMENT_SELECTOR);
+      kernel::cpu::set_efer_bit(kernel::cpu::efer_flags::SCE);
+    }
+
   }  // namespace
 
   auto initialize_descriptor_tables() -> descriptor_tables
@@ -55,17 +91,9 @@ namespace teachos::arch::context_switching
     return tables;
   }
 
-  auto user_mode_main() -> void
-  {
-    kernel::cpu::validate_segment_registers(USER_DATA_SEGMENT_SELECTOR, USER_CODE_SEGMENT_SELECTOR);
-
-    asm volatile("SYSCALL");
-
-    video::vga::text::write("Successfully entered user mode!", video::vga::text::common_attributes::green_on_black);
-  }
-
   auto switch_to_user_mode() -> void
   {
+    enable_systemcall();
     switch_context(USER_DATA_SEGMENT_SELECTOR, USER_CODE_SEGMENT_SELECTOR, user_mode_main);
   }
 
@@ -77,15 +105,4 @@ namespace teachos::arch::context_switching
     kernel::cpu::set_code_segment_register(data_segment, code_segment, reinterpret_cast<uint64_t>(return_function));
   }
 
-  auto setup_syscall() -> void
-  {
-    uint64_t const syscall_function = reinterpret_cast<uint64_t>(syscall_handler);
-    uint64_t const segment_selector = *reinterpret_cast<uint64_t const *>(&KERNEL_CODE_SEGMENT_SELECTOR);
-
-    kernel::cpu::write_msr(IA32_LSTAR_ADDRESS, syscall_function);
-    kernel::cpu::write_msr(IA32_FMASK_ADDRESS, 0U);
-    kernel::cpu::write_msr(IA32_STAR_ADDRESS, segment_selector);
-    kernel::cpu::set_efer_bit(kernel::cpu::efer_flags::SCE);
-  }
-
 }  // namespace teachos::arch::context_switching
diff --git a/arch/x86_64/src/context_switching/syscall_handler.cpp b/arch/x86_64/src/context_switching/syscall_handler.cpp
deleted file mode 100644
index 283d297..0000000
--- a/arch/x86_64/src/context_switching/syscall_handler.cpp
+++ /dev/null
@@ -1,19 +0,0 @@
-#include "arch/context_switching/syscall_handler.hpp"
-
-#include <cstdint>
-
-namespace teachos::arch::context_switching
-{
-  auto syscall_handler() -> void
-  {
-    uint64_t dummy{};
-    switch (dummy)
-    {
-      case 0:
-        break;
-      default:
-        break;
-    }
-    asm volatile("SYSRET");
-  }
-}  // namespace teachos::arch::context_switching
\ No newline at end of file