2 files changed, 42 insertions, 7 deletions
diff --git a/arch/x86_64/include/arch/memory/allocator/area_frame_allocator.hpp b/arch/x86_64/include/arch/memory/allocator/area_frame_allocator.hpp
index c9d4e7f..f99b7c8 100644
--- a/arch/x86_64/include/arch/memory/allocator/area_frame_allocator.hpp
+++ b/arch/x86_64/include/arch/memory/allocator/area_frame_allocator.hpp
@@ -8,6 +8,12 @@
 
 namespace teachos::arch::memory::allocator
 {
+  template<typename T>
+  concept FrameAllocator = requires(T t) {
+    { t.allocate_frame() } -> std::same_as<std::optional<physical_frame>>;
+    { t.deallocate_frame() } -> std::same_as<void>;
+  };
+
   /**
    * @brief Allocates memory using memory areas read from the multiboot2 information pointer.
    */
diff --git a/arch/x86_64/include/arch/memory/paging/page_mapper.hpp b/arch/x86_64/include/arch/memory/paging/page_mapper.hpp
index 635a848..5bdd82a 100644
--- a/arch/x86_64/include/arch/memory/paging/page_mapper.hpp
+++ b/arch/x86_64/include/arch/memory/paging/page_mapper.hpp
@@ -1,6 +1,7 @@
 #ifndef TEACHOS_ARCH_X86_64_MEMORY_PAGING_PAGE_MAPPER_HPP
 #define TEACHOS_ARCH_X86_64_MEMORY_PAGING_PAGE_MAPPER_HPP
 
+#include "arch/exception_handling/assert.hpp"
 #include "arch/memory/allocator/area_frame_allocator.hpp"
 #include "arch/memory/paging/virtual_page.hpp"
 
@@ -34,16 +35,44 @@ namespace teachos::arch::memory::paging
   auto translate_address(std::size_t virtual_address) -> std::optional<std::size_t>;
 
   /**
-   * @brief Maps a virtual page to a physical frame in the page table with the specified flags.
+   * @brief Maps a virtual page to a physical frame in the page table with the specified flags. Allocates and maps an
+   * entry in every page level if it does not exists yet down to level 1. If the level 1 page table already exists it
+   * halts execution instead.
    *
-   * @param allocator Reference to the area frame allocator, which is used to allocate frames when a new page table is
-   * required.
-   * @param page Reference to the virtual page that is being mapped.
-   * @param frame The physical frame that the virtual page will be mapped to.
+   * @param allocator Reference to an allocator following the FrameAllocator concept, which is used to allocate entries
+   * when a new page table is required.
+   * @param page Virtual page that is being mapped.
+   * @param frame Physical frame that the virtual page will be mapped to.
    * @param flags A bitset of flags that configure the page table entry for this mapping.
    */
-  auto map_page_to_frame(allocator::area_frame_allocator & allocator, virtual_page page,
-                         allocator::physical_frame frame, std::bitset<64U> flags) -> void;
+  template<allocator::FrameAllocator T>
+  auto map_page_to_frame(T & allocator, virtual_page page, allocator::physical_frame frame,
+                         std::bitset<64U> flags) -> void
+
+  {
+    page_table page_table{};
+    bool table_exists = false;
+
+    for (auto level = page_table::LEVEL4; level != page_table::LEVEL1; level--)
+    {
+      std::size_t level_index = page.get_level_index(level);
+      table_exists = page_table.next_table(level_index);
+
+      if (!table_exists)
+      {
+        auto allocated_frame = allocator.allocate_frame();
+        exception_handling::assert(!allocated_frame.has_value(), "[Page mapper]: Unable to allocate frame");
+        page_table[level_index].set_entry(allocated_frame.value(), entry::PRESENT | entry::WRITABLE);
+        page_table.zero_entries();
+      }
+    }
+
+    auto level1_entry = page_table[page.get_level_index(page_table::LEVEL1)];
+    arch::exception_handling::assert(!level1_entry.contains_flags(entry::HUGE_PAGE),
+                                     "[Page Mapper]: Unable to map huge pages");
+    arch::exception_handling::assert(!level1_entry.is_unused(), "[Page Mapper]: Page table entry is already used");
+    level1_entry.set_entry(frame, flags | std::bitset<64U>{entry::PRESENT});
+  }
 }  // namespace teachos::arch::memory::paging
 
 #endif  // TEACHOS_ARCH_X86_64_MEMORY_PAGING_PAGE_MAPPER_HPP