x86_64/memory: implement simple kernel remapper

3 files changed, 57 insertions, 0 deletions

diff --git a/arch/x86_64/include/x86_64/memory/kernel_mapper.hpp b/arch/x86_64/include/x86_64/memory/kernel_mapper.hpp
new file mode 100644
index 0000000..4b681ae
--- /dev/null
+++ b/arch/x86_64/include/x86_64/memory/kernel_mapper.hpp
@@ -0,0 +1,33 @@
+#ifndef TEACHOS_X86_64_KERNEL_MAPPER_HPP
+#define TEACHOS_X86_64_KERNEL_MAPPER_HPP
+
+#include "kapi/memory.hpp"
+
+#include <elf/format.hpp>
+#include <elf/section_header.hpp>
+#include <multiboot2/information.hpp>
+
+#include <string_view>
+
+namespace teachos::memory::x86_64
+{
+
+  struct kernel_mapper
+  {
+    using section_header_type = elf::section_header<elf::format::elf64>;
+
+    kernel_mapper(frame_allocator & allocator, multiboot2::information_view const * mbi);
+
+    auto remap_kernel() -> void;
+
+  private:
+    auto map_section(section_header_type const & section, std::string_view name) -> void;
+
+    frame_allocator * m_allocator;
+    multiboot2::information_view const * m_mbi;
+    std::uintptr_t m_kernel_load_base;
+  };
+
+}  // namespace teachos::memory::x86_64
+
+#endif
\ No newline at end of file
diff --git a/arch/x86_64/include/x86_64/memory/page_table.hpp b/arch/x86_64/include/x86_64/memory/page_table.hpp
index c5102a2..ce34e23 100644
--- a/arch/x86_64/include/x86_64/memory/page_table.hpp
+++ b/arch/x86_64/include/x86_64/memory/page_table.hpp
@@ -51,6 +51,12 @@ namespace teachos::memory::x86_64
       //! Get all flags present in this entry.
       [[nodiscard]] auto all_flags() const -> flags;
 
+      //! Set the flags of this entry to the given set.
+      auto all_flags(flags flags) -> void;
+
+      //! Additively set the given flags in this entry.
+      auto operator|=(flags rhs) -> entry &;
+
       //! Get the frame number associated with this entry, if the referenced page is present.
       [[nodiscard]] auto frame() const -> std::optional<frame>;
 
@@ -86,11 +92,21 @@ namespace teachos::memory::x86_64
     return std::bit_cast<page_table::entry::flags>(std::to_underlying(lhs) | std::to_underlying(rhs));
   }
 
+  constexpr auto operator|=(page_table::entry::flags & lhs, page_table::entry::flags rhs) -> page_table::entry::flags &
+  {
+    return lhs = lhs | rhs;
+  }
+
   constexpr auto operator&(page_table::entry::flags lhs, page_table::entry::flags rhs) -> page_table::entry::flags
   {
     return std::bit_cast<page_table::entry::flags>(std::to_underlying(lhs) & std::to_underlying(rhs));
   }
 
+  constexpr auto operator~(page_table::entry::flags flags)
+  {
+    return std::bit_cast<page_table::entry::flags>(~std::to_underlying(flags));
+  }
+
   //! A recursively mapped page table.
   template<std::size_t Level>
     requires(Level > 0uz && Level < 5uz)
diff --git a/arch/x86_64/include/x86_64/memory/paging_root.hpp b/arch/x86_64/include/x86_64/memory/paging_root.hpp
index a9ab6a6..d4aa023 100644
--- a/arch/x86_64/include/x86_64/memory/paging_root.hpp
+++ b/arch/x86_64/include/x86_64/memory/paging_root.hpp
@@ -25,6 +25,14 @@ namespace teachos::memory::x86_64
     [[nodiscard]] auto translate(linear_address address) const -> std::optional<physical_address>;
     [[nodiscard]] auto translate(page page) const -> std::optional<frame>;
 
+    //! Map the given page into the given frame using the given flags.
+    //!
+    //! @param page A page to map.
+    //! @param frame The frame into which to map the page.
+    //! @param flags The flags to apply to the mapping.
+    //! @param allocator The frame allocator used to allocate any required page tables.
+    auto map(page page, frame frame, entry::flags flags, frame_allocator & allocator) -> std::optional<std::byte *>;
+
   private:
     paging_root() = default;
   };