x86_64/kapi: implement remaining mapping steps

4 files changed, 59 insertions, 7 deletions

diff --git a/arch/x86_64/src/kapi/memory.cpp b/arch/x86_64/src/kapi/memory.cpp
index a20483c..abc0526 100644
--- a/arch/x86_64/src/kapi/memory.cpp
+++ b/arch/x86_64/src/kapi/memory.cpp
@@ -1,5 +1,6 @@
 #include "kapi/memory.hpp"
 
+#include "kapi/boot.hpp"
 #include "kapi/cio.hpp"
 #include "kapi/system.hpp"
 
@@ -19,6 +20,7 @@
 #include <multiboot2/information.hpp>
 
 #include <atomic>
+#include <bit>
 #include <memory>
 #include <span>
 
@@ -114,6 +116,42 @@ namespace teachos::memory
       return *new_pml4_frame;
     }
 
+    auto remap_kernel() -> void
+    {
+      auto kernel_mapper = x86_64::kernel_mapper{boot::bootstrap_information.mbi};
+      kernel_mapper.remap_kernel();
+    }
+
+    auto remap_vga_text_mode_buffer(page_mapper & mapper) -> void
+    {
+      constexpr auto vga_base = std::uintptr_t{0xb8000};
+      auto vga_physical_start = physical_address{vga_base};
+      auto vga_virtual_start = linear_address{vga_base + std::bit_cast<std::uintptr_t>(&boot::x86_64::TEACHOS_VMA)};
+
+      auto page = page::containing(vga_virtual_start);
+      auto frame = frame::containing(vga_physical_start);
+
+      mapper.map(page, frame, page_mapper::flags::writable);
+    }
+
+    auto remap_multiboot_information(page_mapper & mapper) -> void
+    {
+      auto mbi_base = std::bit_cast<std::uintptr_t>(boot::bootstrap_information.mbi);
+      auto mbi_size = boot::bootstrap_information.mbi->size_bytes();
+      auto mbi_physical_start = physical_address{mbi_base};
+      auto mbi_virtual_start = linear_address{mbi_base + std::bit_cast<std::uintptr_t>(&boot::x86_64::TEACHOS_VMA)};
+      auto mbi_block_count = (mbi_size + PLATFORM_FRAME_SIZE - 1) / PLATFORM_FRAME_SIZE;
+
+      for (auto i = 0uz; i < mbi_block_count; ++i)
+      {
+        auto page = page::containing(mbi_virtual_start) + 1;
+        auto frame = frame::containing(mbi_physical_start) + 1;
+        mapper.map(page, frame, page_mapper::flags::empty);
+      }
+
+      boot::bootstrap_information.mbi = std::bit_cast<multiboot2::information_view const *>(mbi_virtual_start.raw());
+    }
+
   }  // namespace
 
   auto active_frame_allocator() -> frame_allocator &
@@ -138,11 +176,14 @@ namespace teachos::memory
   auto init() -> void
   {
     auto static constinit is_initialized = std::atomic_flag{};
+
     if (is_initialized.test_and_set())
     {
       system::panic("[x86_64] Memory management has already been initialized.");
     }
 
+    cio::println("[x86_64:MEM] Enabling additional CPU protection features.");
+
     enable_cpu_protections();
 
     auto early_allocator = create_early_frame_allocator();
@@ -154,17 +195,18 @@ namespace teachos::memory
 
     auto new_pml4_frame = inject_faux_pml4(allocation_buffer);
 
-    auto kernel_mapper = x86_64::kernel_mapper{boot::bootstrap_information.mbi};
-    kernel_mapper.remap_kernel();
-    cio::println("[x86_64:MEM] prepared new kernel image page maps.");
+    cio::println("[x86_64:MEM] Preparing new paging hierarchy.");
+
+    remap_kernel();
+    remap_vga_text_mode_buffer(recursive_mapper);
+    remap_multiboot_information(recursive_mapper);
+
+    cio::println("[x86_64:MEM] Switching to new paging hierarchy.");
 
     auto cr3 = cpu::x86_64::cr3::read();
     cr3.address(new_pml4_frame.start_address());
     cpu::x86_64::cr3::write(cr3);
 
-    // remap_heap(heap::KERNEL_HEAP_START, heap::KERNEL_HEAP_SIZE);
-    // video::vga::text::write("Heap remapping successful", video::vga::text::common_attributes::green_on_black);
-    // video::vga::text::newline();
     mapper = nullptr;
     allocator = nullptr;
   }
diff --git a/kapi/include/kapi/boot.hpp b/kapi/include/kapi/boot.hpp
index 9c344cf..dd99198 100644
--- a/kapi/include/kapi/boot.hpp
+++ b/kapi/include/kapi/boot.hpp
@@ -11,7 +11,7 @@ namespace teachos::boot
 
   //! @qualifier platform-defined
   //! An object passed from the early pre-main stage to the kernel executable.
-  extern "C" information const bootstrap_information;
+  extern "C" information bootstrap_information;
 }  // namespace teachos::boot
 
 #endif
diff --git a/kapi/include/kapi/memory/page.hpp b/kapi/include/kapi/memory/page.hpp
index 66e8482..0b7083a 100644
--- a/kapi/include/kapi/memory/page.hpp
+++ b/kapi/include/kapi/memory/page.hpp
@@ -51,6 +51,15 @@ namespace teachos::memory
       return m_number;
     }
 
+    //! Get a handle n pages after the one referenced by this handle.
+    //!
+    //! @param n The positive offset to this page.
+    //! @return A handle referencing the page n pages after the one referenced by this handle.
+    constexpr auto operator+(std::size_t n) const noexcept -> page
+    {
+      return page{m_number + n};
+    }
+
     //! Check if this page handle reference the same frame as another one.
     //!
     //! @param other Another page handle.
diff --git a/src/main.cpp b/src/main.cpp
index fc7d2f4..3394275 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -8,6 +8,7 @@ auto main() -> int
   teachos::cio::println("[OS] IO subsystem initialized.");
 
   teachos::memory::init();
+  teachos::cio::println("[OS] Memory subsystem initialized.");
 
   teachos::system::panic("Returning from kernel main!");
 }