x86_64/memory: extend scoped_mapping

6 files changed, 81 insertions, 1 deletions

diff --git a/arch/x86_64/CMakeLists.txt b/arch/x86_64/CMakeLists.txt
index 4d32f76..f010dcf 100644
--- a/arch/x86_64/CMakeLists.txt
+++ b/arch/x86_64/CMakeLists.txt
@@ -52,6 +52,7 @@ target_sources("x86_64" PRIVATE
     # Memory management
     "include/x86_64/memory/mmu.hpp"
     "include/x86_64/memory/page_table.hpp"
+    "include/x86_64/memory/page_utilities.hpp"
     "include/x86_64/memory/paging_root.hpp"
     "include/x86_64/memory/region_allocator.hpp"
     "include/x86_64/memory/scoped_mapping.hpp"
diff --git a/arch/x86_64/include/x86_64/memory/page_utilities.hpp b/arch/x86_64/include/x86_64/memory/page_utilities.hpp
new file mode 100644
index 0000000..efd1b80
--- /dev/null
+++ b/arch/x86_64/include/x86_64/memory/page_utilities.hpp
@@ -0,0 +1,22 @@
+#ifndef TEACHOS_X86_64_PAGE_UTILITIES_HPP
+#define TEACHOS_X86_64_PAGE_UTILITIES_HPP
+
+#include "kapi/memory.hpp"
+
+#include <cstddef>
+
+namespace teachos::memory::x86_64
+{
+
+  template<std::size_t Level>
+    requires(Level > 0uz && Level < 5uz)
+  constexpr auto pml_index(page page) noexcept -> std::size_t
+  {
+    constexpr auto shift_width = (Level - 1) * 9;
+    constexpr auto index_mask = 0x1ffuz;
+    return page.number() >> shift_width & index_mask;
+  }
+
+}  // namespace teachos::memory::x86_64
+
+#endif
\ No newline at end of file
diff --git a/arch/x86_64/src/memory/paging_root.cpp b/arch/x86_64/src/memory/paging_root.cpp
index 1234308..6b65f60 100644
--- a/arch/x86_64/src/memory/paging_root.cpp
+++ b/arch/x86_64/src/memory/paging_root.cpp
@@ -1,6 +1,11 @@
 #include "x86_64/memory/paging_root.hpp"
 
+#include "kapi/memory.hpp"
+
+#include "x86_64/memory/page_utilities.hpp"
+
 #include <cstdint>
+#include <optional>
 
 namespace teachos::memory::x86_64
 {
@@ -16,4 +21,40 @@ namespace teachos::memory::x86_64
     return *pml4_address;
   }
 
+  auto paging_root::translate(linear_address address) const -> std::optional<physical_address>
+  {
+    auto offset = address.raw() % PLATFORM_PAGE_SIZE;
+    return translate(page::containing(address)).transform([offset](auto frame) -> auto {
+      return physical_address{frame.start_address().raw() + offset};
+    });
+  }
+
+  auto paging_root::translate(page page) const -> std::optional<frame>
+  {
+    auto pml3 = next(pml_index<4>(page));
+
+    if (!pml3)
+    {
+      return std::nullopt;
+    }
+
+    auto handle_huge_page = [&] -> std::optional<frame> {
+      auto pml3_entry = pml3.transform([&](auto pml3) -> auto { return (*pml3)[pml_index<3>(page)]; });
+      if (pml3_entry && pml3_entry->huge())
+      {
+        auto pml3_entry_frame = *pml3_entry->frame();
+        return frame{pml3_entry_frame.number() + pml_index<2>(page) * entry_count + pml_index<1>(page)};
+      }
+
+      // auto pml3_entry = (**pml3)[page.start_address().raw() >> 39 & 0x1ff];
+
+      return std::nullopt;
+    };
+
+    return pml3.and_then([&](auto pml3) -> auto { return pml3->next(pml_index<3>(page)); })
+        .and_then([&](auto pml2) -> auto { return pml2->next(pml_index<2>(page)); })
+        .and_then([&](auto pml1) -> auto { return (*pml1)[pml_index<1>(page)].frame(); })
+        .or_else(handle_huge_page);
+  }
+
 }  // namespace teachos::memory::x86_64
\ No newline at end of file
diff --git a/arch/x86_64/src/memory/scoped_mapping.cpp b/arch/x86_64/src/memory/scoped_mapping.cpp
index c436ee5..27c4785 100644
--- a/arch/x86_64/src/memory/scoped_mapping.cpp
+++ b/arch/x86_64/src/memory/scoped_mapping.cpp
@@ -4,6 +4,7 @@
 #include "kapi/system.hpp"
 
 #include "x86_64/memory/mmu.hpp"
+#include "x86_64/memory/paging_root.hpp"
 
 #include <utility>
 
@@ -20,7 +21,12 @@ namespace teachos::memory::x86_64
       : m_address{address}
       , m_allocator{&allocator}
       , m_mapped{false}
-  {}
+  {
+    if (paging_root::get().translate(address))
+    {
+      system::panic("[MEM] Tried to map a page that is already mapped!");
+    }
+  }
 
   scoped_mapping::~scoped_mapping()
   {
diff --git a/kapi/include/kapi/memory/frame.hpp b/kapi/include/kapi/memory/frame.hpp
index 095a3df..5793b8b 100644
--- a/kapi/include/kapi/memory/frame.hpp
+++ b/kapi/include/kapi/memory/frame.hpp
@@ -42,6 +42,11 @@ namespace teachos::memory
       return physical_address{m_number * PLATFORM_FRAME_SIZE};
     }
 
+    [[nodiscard]] constexpr auto number() const noexcept -> std::size_t
+    {
+      return m_number;
+    }
+
     /**
      * @brief Get the nth next frame.
      *
diff --git a/kapi/include/kapi/memory/page.hpp b/kapi/include/kapi/memory/page.hpp
index b84094f..473a8b8 100644
--- a/kapi/include/kapi/memory/page.hpp
+++ b/kapi/include/kapi/memory/page.hpp
@@ -42,6 +42,11 @@ namespace teachos::memory
       return linear_address{m_number * PLATFORM_PAGE_SIZE};
     }
 
+    [[nodiscard]] constexpr auto number() const noexcept -> std::size_t
+    {
+      return m_number;
+    }
+
     /**
      * @brief Check if this page refers to the same page as @p other.
      */