From 203355e51690073e571d4906d53f2494c3dad41b Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Mon, 1 Dec 2025 19:32:19 +0100
Subject: x86_64/memory: prepare scoped_mapping extraction

---
 arch/x86_64/src/kapi/memory.cpp           | 12 +++++
 arch/x86_64/src/memory/scoped_mapping.cpp | 73 +++++++++++++++++++++++++++++++
 2 files changed, 85 insertions(+)
 create mode 100644 arch/x86_64/src/memory/scoped_mapping.cpp

(limited to 'arch/x86_64/src')

diff --git a/arch/x86_64/src/kapi/memory.cpp b/arch/x86_64/src/kapi/memory.cpp
index f34729a..920c82b 100644
--- a/arch/x86_64/src/kapi/memory.cpp
+++ b/arch/x86_64/src/kapi/memory.cpp
@@ -10,6 +10,7 @@
 #include "x86_64/memory/page_table.hpp"
 #include "x86_64/memory/paging_root.hpp"
 #include "x86_64/memory/region_allocator.hpp"
+#include "x86_64/memory/scoped_mapping.hpp"
 
 #include <multiboot2/information.hpp>
 
@@ -140,8 +141,19 @@ namespace teachos::memory
 
     auto allocator = create_early_frame_allocator();
     enable_cpu_protections();
+
+    // TODO: remove
     inject_faux_pml4(allocator);
 
+    // TODO: implement
+    auto temporary_mapper = x86_64::scoped_mapping{linear_address{unused_page_address}, allocator};
+    auto new_pml4_frame = allocator.allocate();
+
+    auto new_plm4 = temporary_mapper.map_as<x86_64::page_table>(
+        *new_pml4_frame, x86_64::page_table::entry::flags::present | x86_64::page_table::entry::flags::writable);
+    (*new_plm4)[510].frame(new_pml4_frame.value(),
+                           x86_64::page_table::entry::flags::present | x86_64::page_table::entry::flags::writable);
+
     // paging::kernel_mapper kernel(allocator, memory_information);
     // kernel.remap_kernel();
     // video::vga::text::write("Kernel remapping successful", video::vga::text::common_attributes::green_on_black);
diff --git a/arch/x86_64/src/memory/scoped_mapping.cpp b/arch/x86_64/src/memory/scoped_mapping.cpp
new file mode 100644
index 0000000..c436ee5
--- /dev/null
+++ b/arch/x86_64/src/memory/scoped_mapping.cpp
@@ -0,0 +1,73 @@
+#include "x86_64/memory/scoped_mapping.hpp"
+
+#include "kapi/memory.hpp"
+#include "kapi/system.hpp"
+
+#include "x86_64/memory/mmu.hpp"
+
+#include <utility>
+
+namespace teachos::memory::x86_64
+{
+
+  scoped_mapping::scoped_mapping(scoped_mapping && other)
+      : m_address{std::exchange(other.m_address, linear_address{})}
+      , m_allocator{std::exchange(other.m_allocator, nullptr)}
+      , m_mapped{std::exchange(other.m_mapped, false)}
+  {}
+
+  scoped_mapping::scoped_mapping(linear_address address, frame_allocator & allocator)
+      : m_address{address}
+      , m_allocator{&allocator}
+      , m_mapped{false}
+  {}
+
+  scoped_mapping::~scoped_mapping()
+  {
+    if (m_mapped)
+    {
+      unmap();
+      x86_64::tlb_flush(m_address);
+    }
+  }
+
+  auto scoped_mapping::operator=(scoped_mapping && other) -> scoped_mapping &
+  {
+    if (&other == this)
+    {
+      return *this;
+    }
+
+    using std::swap;
+
+    swap(m_address, other.m_address);
+    swap(m_allocator, other.m_allocator);
+    swap(m_mapped, other.m_mapped);
+
+    return *this;
+  }
+
+  auto scoped_mapping::map(frame frame, page_table::entry::flags flags) -> std::byte *
+  {
+    static_cast<void>(frame);
+    static_cast<void>(flags);
+
+    m_mapped = true;
+
+    return nullptr;
+  }
+
+  auto scoped_mapping::unmap() -> void
+  {
+    if (!m_mapped)
+    {
+      system::panic("[MEM] Tried to release an unmapped temporary mapping!");
+    }
+
+    // TODO: scan pages
+    // TODO: remove mapping
+    // TODO: release temporary table frames
+    m_mapped = false;
+  }
+
+}  // namespace teachos::memory::x86_64
\ No newline at end of file
-- 
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