Fix issue in vector

1 files changed, 12 insertions, 15 deletions

diff --git a/arch/x86_64/src/context_switching/descriptor_table/global_descriptor_table.cpp b/arch/x86_64/src/context_switching/descriptor_table/global_descriptor_table.cpp
index 77bd3e9..21a76e8 100644
--- a/arch/x86_64/src/context_switching/descriptor_table/global_descriptor_table.cpp
+++ b/arch/x86_64/src/context_switching/descriptor_table/global_descriptor_table.cpp
@@ -54,9 +54,12 @@ namespace teachos::arch::context_switching::descriptor_table
         create_segment_descriptor(segment_descriptor_type::CODE_SEGMENT, access_level::USER);
     segment_descriptor user_data_segment =
         create_segment_descriptor(segment_descriptor_type::DATA_SEGMENT, access_level::USER);
+    // Task State Segment needs to be kept alive
+    static auto tss = new task_state_segment();
+    segment_descriptor tss_descriptor = create_task_state_segment_descriptor(tss);
 
-    global_descriptor_table global_descriptor_table{null_segment, kernel_code_segment, kernel_data_segment,
-                                                    user_code_segment, user_data_segment};
+    global_descriptor_table global_descriptor_table{null_segment,      kernel_code_segment, kernel_data_segment,
+                                                    user_code_segment, user_data_segment,   tss_descriptor};
     return global_descriptor_table;
   }
 
@@ -67,20 +70,15 @@ namespace teachos::arch::context_switching::descriptor_table
                                 access_byte::TASK_STATE_SEGMENT_AVAILABLE};
     gdt_flags tss_gdt_flags{0U, limit};
     uint64_t tss_address = reinterpret_cast<uint64_t>(tss);
-    constexpr uint64_t tss_limit = sizeof(task_state_segment) - 1;
-    segment_descriptor tss_descriptor{tss_access_byte, tss_gdt_flags, tss_address, tss_limit};
-
+    constexpr uint64_t TSS_LIMIT = sizeof(task_state_segment) - 1;
+    segment_descriptor tss_descriptor{tss_access_byte, tss_gdt_flags, tss_address, TSS_LIMIT};
     return tss_descriptor;
   }
 
-  auto initialize_global_descriptor_table() -> global_descriptor_table
+  auto initialize_global_descriptor_table() -> global_descriptor_table &
   {
-    auto gdt = create_global_descriptor_table();
-
-    // Add TSS segment descriptor to GDT
-    auto tss = new task_state_segment();
-    auto tss_descriptor = create_task_state_segment_descriptor(tss);
-    gdt.push_back(tss_descriptor);
+    // Global Descriptor Table needs to be kept alive
+    static auto gdt = create_global_descriptor_table();
 
     // Load GDT into GDTR
     global_descriptor_table_pointer gdt_pointer{static_cast<uint16_t>(gdt.size() - 1), &gdt};
@@ -91,14 +89,13 @@ namespace teachos::arch::context_switching::descriptor_table
         gdt_pointer == stored_gdt_pointer,
         "[Global Descriptor Table] Loaded GDTR value is not the same as the stored value.");
 
-    // Load Task Register (LTR) using the index of TSS descriptor
-    uint16_t tss_selector = (gdt.size() - 1) * sizeof(segment_descriptor);
+    // Calculate the offset of the gdt in bytes to the TSS descriptor
+    uint16_t const tss_selector = (gdt.size() - 1) * sizeof(segment_descriptor);
     kernel::cpu::load_task_register(tss_selector);
 
     auto stored_task_register = kernel::cpu::store_task_register();
     arch::exception_handling::assert(tss_selector == stored_task_register,
                                      "[Global Descriptor Table] Loaded TR value is not the same as the stored value.");
-
     return gdt;
   }
 }  // namespace teachos::arch::context_switching::descriptor_table