wip

6 files changed, 38 insertions, 20 deletions

diff --git a/arch/x86_64/include/arch/boot/pointers.hpp b/arch/x86_64/include/arch/boot/pointers.hpp
index 37840b6..2c42605 100644
--- a/arch/x86_64/include/arch/boot/pointers.hpp
+++ b/arch/x86_64/include/arch/boot/pointers.hpp
@@ -9,6 +9,8 @@ namespace teachos::arch::boot
 {
   extern "C" size_t const multiboot_information_pointer;
   extern "C" memory::paging::page_table * page_map_level_4;
+  extern "C" memory::paging::page_table * page_map_level_3;
+  extern "C" memory::paging::page_table * page_map_level_2;
 }  // namespace teachos::arch::boot
 
 #endif
diff --git a/arch/x86_64/include/arch/memory/paging/page_table.hpp b/arch/x86_64/include/arch/memory/paging/page_table.hpp
index 8250e30..5a072d0 100644
--- a/arch/x86_64/include/arch/memory/paging/page_table.hpp
+++ b/arch/x86_64/include/arch/memory/paging/page_table.hpp
@@ -47,6 +47,11 @@ namespace teachos::arch::memory::paging
     page_table_handle(page_table * handle, level handle_level);
 
     /**
+     * @brief Initializes one page table level 3 entry.
+     */
+    void initialize_page_table();
+
+    /**
      * @brief Set every entry of the page to unused.
      */
     auto zero_entries() -> void;
diff --git a/arch/x86_64/scripts/kernel.ld b/arch/x86_64/scripts/kernel.ld
index e244ce1..3449828 100644
--- a/arch/x86_64/scripts/kernel.ld
+++ b/arch/x86_64/scripts/kernel.ld
@@ -59,13 +59,14 @@ SECTIONS
     *(.boot_stack)
   }
 
+  . = ALIGN(4K);
+  _end_of_image = .;
+
   /***************************************************************************
    * Now it is time to load the 64-bit kernel code. We virtually load it into
    * the upper 2GiB, while adjusting the linear load address appropriately. We
    * also make sure to align the loaded data onto a page boundary.
    ***************************************************************************/
-  . = ALIGN(4K);
-
   .init ALIGN(4K) : AT(ADDR (.init))
   {
     /* 
@@ -126,9 +127,6 @@ SECTIONS
     *(.bss*)
   }
 
-  . = ALIGN(4K);
-  _end_of_image = .;
-
   /***************************************************************************
    * In accordance with the symbol definitions at the start, we generate some
    * symbols to mark the end of our loaded image.
diff --git a/arch/x86_64/src/boot/boot.s b/arch/x86_64/src/boot/boot.s
index 7d6b322..6ed1e0a 100644
--- a/arch/x86_64/src/boot/boot.s
+++ b/arch/x86_64/src/boot/boot.s
@@ -24,11 +24,11 @@
 .global page_map_level_4
 page_map_level_4: .skip 512 * 8
 
-.global page_map_level_3_low
-page_map_level_3_low: .skip 512 * 8
+.global page_map_level_3
+page_map_level_3: .skip 512 * 8
 
-.global page_map_level_2_low
-page_map_level_2_low: .skip 512 * 8
+.global page_map_level_2
+page_map_level_2: .skip 512 * 8
 
 /**
  * Reserve some space for the Multiboot 2 information pointer.
@@ -318,14 +318,14 @@ enable_sse:
  */
 prepare_page_maps:
     /* Add an entry to the PML4, pointing to the low PML3 */
-    mov $page_map_level_3_low, %eax
+    mov $page_map_level_3, %eax
     or $0x3, %eax
     mov %eax, (page_map_level_4 + ((0x0000000000100000 >> 39) & 0x1ff) * 8)
 
     /* Add an entry to the low PML3, pointing to the low PML2 */
-    mov $page_map_level_2_low, %eax
+    mov $page_map_level_2, %eax
     or $0x3, %eax
-    mov %eax, (page_map_level_3_low + ((0x0000000000100000 >> 30) & 0x1ff) * 8)
+    mov %eax, (page_map_level_3 + ((0x0000000000100000 >> 30) & 0x1ff) * 8)
 
     xor %ecx, %ecx
 
@@ -337,7 +337,7 @@ prepare_page_maps:
     mov $(1 << 21), %eax
     mul %ecx
     or $((1 << 0) | (1 << 1) | (1 << 7)), %eax
-    mov %eax, page_map_level_2_low(,%ecx,8)
+    mov %eax, page_map_level_2(,%ecx,8)
 
     inc %ecx
     cmp %esi, %ecx
diff --git a/arch/x86_64/src/memory/paging/page_mapper.cpp b/arch/x86_64/src/memory/paging/page_mapper.cpp
index cd77366..dff9ae4 100644
--- a/arch/x86_64/src/memory/paging/page_mapper.cpp
+++ b/arch/x86_64/src/memory/paging/page_mapper.cpp
@@ -4,10 +4,20 @@
 
 namespace teachos::arch::memory::paging
 {
+
   auto create_or_get() -> page_table_handle
   {
+    static auto initialized = false;
     // TODO: As soon as linker error is fixed in toolchain make handle static and return that.
-    return page_table_handle{arch::boot::page_map_level_4, page_table_handle::LEVEL4};
+    page_table_handle active_handle{boot::page_map_level_4, page_table_handle::LEVEL4};
+
+    if (!initialized)
+    {
+      active_handle.initialize_page_tables();
+      initialized = true;
+    }
+
+    return active_handle;
   }
 
   auto translate_page(virtual_page page) -> std::optional<allocator::physical_frame>
diff --git a/arch/x86_64/src/memory/paging/page_table.cpp b/arch/x86_64/src/memory/paging/page_table.cpp
index 2f97a80..b5315a0 100644
--- a/arch/x86_64/src/memory/paging/page_table.cpp
+++ b/arch/x86_64/src/memory/paging/page_table.cpp
@@ -11,11 +11,6 @@ namespace teachos::arch::memory::paging
   struct page_table
   {
     /**
-     * @brief Defaulted constructor.
-     */
-    page_table() = default;
-
-    /**
      * @brief Set every entry of the page to unused.
      */
     auto zero_entries() -> void;
@@ -105,7 +100,15 @@ namespace teachos::arch::memory::paging
       : handle(handle)
       , handle_level(handle_level)
   {
-    exception_handling::assert(handle, "[Page table] Attempted to pass nullptr as handle to page table handle method");
+    exception_handling::assert(handle, "[Page Table] Attempted to pass nullptr as handle to page table handle method");
+  }
+
+  auto page_table_handle::initialize_page_table() -> void
+  {
+    exception_handling::assert(handle_level == page_table_handle::LEVEL4,
+                               "[Page Table] Attempted to initialize a page table of level 3 or lower");
+
+    auto level_3_page_table = boot::page_map_level_3;
   }
 
   auto page_table_handle::zero_entries() -> void { handle->zero_entries(); }