move context_switch function and environment into different directory

2 files changed, 11 insertions, 54 deletions

diff --git a/arch/x86_64/src/kernel/cpu/segment_register.cpp b/arch/x86_64/src/kernel/cpu/segment_register.cpp
index d7857dd..9fb7433 100644
--- a/arch/x86_64/src/kernel/cpu/segment_register.cpp
+++ b/arch/x86_64/src/kernel/cpu/segment_register.cpp
@@ -30,4 +30,13 @@ namespace teachos::arch::kernel::cpu
                  : [input] "m"(segment_selector));
   }
 
+  auto read_code_segment_register() -> context_switching::interrupt_descriptor_table::segment_selector
+  {
+    context_switching::interrupt_descriptor_table::segment_selector current_value;
+    asm volatile("mov %%cs, %[output]" : [output] "=r"(current_value));
+    return current_value;
+  }
+
+  auto validate_segment_registers() -> context_switching::interrupt_descriptor_table::segment_selector {}
+
 }  // namespace teachos::arch::kernel::cpu
diff --git a/arch/x86_64/src/kernel/main.cpp b/arch/x86_64/src/kernel/main.cpp
index ac2591e..b69064d 100644
--- a/arch/x86_64/src/kernel/main.cpp
+++ b/arch/x86_64/src/kernel/main.cpp
@@ -50,50 +50,6 @@ namespace teachos::arch::kernel
     delete test9;
   }
 
-  auto return_function() -> void
-  {
-    video::vga::text::write("User Mode!!!", video::vga::text::common_attributes::green_on_black);
-  }
-
-  /**
-   * @brief Switch context into the mode defined in the segment selectors.
-   *
-   * Setup the stack IRETQ expects to switch the mode:
-   * 1. push data selector
-   * 2. push current stack pointer
-   * 3. push eflags
-   * 4. push code segment selector
-   * 5. push return address
-   *
-   * @param data_segment
-   * @param code_segment
-   * @param address
-   */
-  [[gnu::naked]]
-  auto switch_context(context_switching::interrupt_descriptor_table::segment_selector data_segment,
-                      context_switching::interrupt_descriptor_table::segment_selector code_segment, uint64_t address)
-      -> void
-  {
-    asm volatile("mov %[data_segment], %%rax\n"
-                 "mov %%rax, %%ds\n"
-                 "mov %%rax, %%es\n"
-                 "mov %%rax, %%fs\n"
-                 "mov %%rax, %%gs\n"
-                 "mov %%rsp, %%rax\n"
-
-                 "push %[data_segment]\n"
-                 "push %%rax\n"
-                 "pushfq\n"
-                 "push %[code_segment]\n"
-                 "mov %[return_function], %%rax\n"
-                 "push %%rax\n"
-
-                 "iretq\n"
-                 :
-                 : [data_segment] "m"(data_segment), [code_segment] "m"(code_segment), [return_function] "r"(address)
-                 : "rax");
-  }
-
   auto main() -> void
   {
     video::vga::text::clear();
@@ -109,16 +65,8 @@ namespace teachos::arch::kernel
     heap_test();
 
     decltype(auto) descriptor_tables = context_switching::initialize_descriptor_tables();
-
-    context_switching::interrupt_descriptor_table::segment_selector user_code_segment_selector{
-        3U, context_switching::interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_USER};
-    context_switching::interrupt_descriptor_table::segment_selector user_data_segment_selector{
-        4U, context_switching::interrupt_descriptor_table::segment_selector::REQUEST_LEVEL_USER};
-
-    cpu::set_segment_registers(user_data_segment_selector);
-    switch_context(user_data_segment_selector, user_code_segment_selector,
-                   reinterpret_cast<uint64_t>(&return_function));
-
     (void)descriptor_tables;
+
+    context_switching::switch_to_user_mode();
   }
 }  // namespace teachos::arch::kernel