From 36758071881088b27a52cee4e5653f6cf6a79a78 Mon Sep 17 00:00:00 2001
From: Fabian Imhof <fabian.imhof@ost.ch>
Date: Sun, 16 Mar 2025 12:41:09 +0000
Subject: start implementing TSS

---
 arch/x86_64/src/kernel/cpu/gdtr.cpp | 20 ++++++++++++++++++++
 arch/x86_64/src/kernel/cpu/lgdt.cpp | 20 --------------------
 arch/x86_64/src/kernel/cpu/tr.cpp   | 17 +++++++++++++++++
 arch/x86_64/src/kernel/main.cpp     |  1 -
 4 files changed, 37 insertions(+), 21 deletions(-)
 create mode 100644 arch/x86_64/src/kernel/cpu/gdtr.cpp
 delete mode 100644 arch/x86_64/src/kernel/cpu/lgdt.cpp
 create mode 100644 arch/x86_64/src/kernel/cpu/tr.cpp

(limited to 'arch/x86_64/src/kernel')

diff --git a/arch/x86_64/src/kernel/cpu/gdtr.cpp b/arch/x86_64/src/kernel/cpu/gdtr.cpp
new file mode 100644
index 0000000..2fe3a99
--- /dev/null
+++ b/arch/x86_64/src/kernel/cpu/gdtr.cpp
@@ -0,0 +1,20 @@
+#include "arch/kernel/cpu/gdtr.hpp"
+
+#include "arch/context_switching/descriptor_table/global_descriptor_table_pointer.hpp"
+
+namespace teachos::arch::kernel::cpu
+{
+  auto store_global_descriptor_table() -> context_switching::descriptor_table::global_descriptor_table_pointer
+  {
+    context_switching::descriptor_table::global_descriptor_table_pointer current_value{};
+    asm("sgdt %[output]" : [output] "=m"(current_value));
+    return current_value;
+  }
+
+  auto
+  load_global_descriptor_table(context_switching::descriptor_table::global_descriptor_table_pointer const & gdt_pointer)
+      -> void
+  {
+    asm volatile("lgdt %[input]" : /* no output from call */ : [input] "m"(gdt_pointer));
+  }
+}  // namespace teachos::arch::kernel::cpu
diff --git a/arch/x86_64/src/kernel/cpu/lgdt.cpp b/arch/x86_64/src/kernel/cpu/lgdt.cpp
deleted file mode 100644
index 386914f..0000000
--- a/arch/x86_64/src/kernel/cpu/lgdt.cpp
+++ /dev/null
@@ -1,20 +0,0 @@
-#include "arch/kernel/cpu/lgdt.hpp"
-
-#include "arch/context_switching/descriptor_table/global_descriptor_table_pointer.hpp"
-
-namespace teachos::arch::kernel::cpu
-{
-  auto store_global_descriptor_table() -> context_switching::descriptor_table::global_descriptor_table_pointer
-  {
-    context_switching::descriptor_table::global_descriptor_table_pointer current_value{};
-    asm("sgdt %[output]" : [output] "=m"(current_value));
-    return current_value;
-  }
-
-  auto
-  load_global_descriptor_table(context_switching::descriptor_table::global_descriptor_table_pointer const & gdt_pointer)
-      -> void
-  {
-    asm volatile("lgdt %[input]" : /* no output from call */ : [input] "m"(gdt_pointer));
-  }
-}  // namespace teachos::arch::kernel::cpu
diff --git a/arch/x86_64/src/kernel/cpu/tr.cpp b/arch/x86_64/src/kernel/cpu/tr.cpp
new file mode 100644
index 0000000..a28b9fc
--- /dev/null
+++ b/arch/x86_64/src/kernel/cpu/tr.cpp
@@ -0,0 +1,17 @@
+#include "arch/kernel/cpu/tr.hpp"
+
+namespace teachos::arch::kernel::cpu
+{
+  auto store_task_register() -> uint16_t
+  {
+    uint16_t current_value{};
+    asm("str %[output]" : [output] "=m"(current_value));
+    return current_value;
+  }
+
+  // TODO: Is this really correct?
+  auto load_task_register(uint16_t gdt_offset) -> void
+  {
+    asm volatile("ltr %[input]" : /* no output from call */ : [input] "m"(gdt_offset));
+  }
+}  // namespace teachos::arch::kernel::cpu
diff --git a/arch/x86_64/src/kernel/main.cpp b/arch/x86_64/src/kernel/main.cpp
index 2c0b6c8..c1e134a 100644
--- a/arch/x86_64/src/kernel/main.cpp
+++ b/arch/x86_64/src/kernel/main.cpp
@@ -1,7 +1,6 @@
 #include "arch/kernel/main.hpp"
 
 #include "arch/context_switching/descriptor_table/global_descriptor_table.hpp"
-#include "arch/kernel/cpu/lgdt.hpp"
 #include "arch/memory/heap/bump_allocator.hpp"
 #include "arch/memory/heap/global_heap_allocator.hpp"
 #include "arch/memory/main.hpp"
-- 
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