From 1db039ca1c67e8daba8b5ec6d5158cb2110e1410 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Fri, 28 Nov 2025 16:06:15 +0100
Subject: x86_64: port basic page and page table abstractions

---
 arch/x86_64/src/memory/page_table.cpp  | 57 ++++++++++++++++++++++++++++++++++
 arch/x86_64/src/memory/paging_root.cpp | 19 ++++++++++++
 2 files changed, 76 insertions(+)
 create mode 100644 arch/x86_64/src/memory/page_table.cpp
 create mode 100644 arch/x86_64/src/memory/paging_root.cpp

(limited to 'arch/x86_64/src/memory')

diff --git a/arch/x86_64/src/memory/page_table.cpp b/arch/x86_64/src/memory/page_table.cpp
new file mode 100644
index 0000000..c716c5c
--- /dev/null
+++ b/arch/x86_64/src/memory/page_table.cpp
@@ -0,0 +1,57 @@
+#include "x86_64/memory/page_table.hpp"
+
+#include <algorithm>
+
+namespace teachos::memory::x86_64
+{
+
+  auto page_table::entry::clear() -> void
+  {
+    m_raw = 0;
+  }
+
+  auto page_table::entry::present() const -> bool
+  {
+    return (flags() & flags::present) != flags::empty;
+  }
+
+  auto page_table::entry::huge() const -> bool
+  {
+    return (flags() & flags::huge_page) != flags::empty;
+  }
+
+  auto page_table::entry::all_flags() const -> flags
+  {
+    return std::bit_cast<flags>(m_raw & ~frame_number_mask);
+  }
+
+  auto page_table::entry::frame() const -> std::optional<struct frame>
+  {
+    if (present())
+    {
+      return frame::containing(physical_address{m_raw & frame_number_mask});
+    }
+    return std::nullopt;
+  }
+
+  auto page_table::entry::frame(struct frame frame, flags flags) -> void
+  {
+    m_raw = (frame.start_address().raw() | static_cast<std::uint64_t>(flags));
+  };
+
+  auto page_table::operator[](std::size_t index) -> entry &
+  {
+    return m_entries.at(index);
+  }
+
+  auto page_table::operator[](std::size_t index) const -> entry const &
+  {
+    return m_entries.at(index);
+  }
+
+  auto page_table::clear() -> void
+  {
+    std::ranges::for_each(m_entries, &page_table::entry::clear);
+  }
+
+}  // namespace teachos::memory::x86_64
diff --git a/arch/x86_64/src/memory/paging_root.cpp b/arch/x86_64/src/memory/paging_root.cpp
new file mode 100644
index 0000000..1234308
--- /dev/null
+++ b/arch/x86_64/src/memory/paging_root.cpp
@@ -0,0 +1,19 @@
+#include "x86_64/memory/paging_root.hpp"
+
+#include <cstdint>
+
+namespace teachos::memory::x86_64
+{
+
+  namespace
+  {
+    constexpr auto PML_RECURSIVE_BASE = std::uintptr_t{0177777'776'776'776'776'0000uz};
+  }
+
+  auto paging_root::get() -> paging_root &
+  {
+    auto pml4_address = std::bit_cast<paging_root *>(PML_RECURSIVE_BASE);
+    return *pml4_address;
+  }
+
+}  // namespace teachos::memory::x86_64
\ No newline at end of file
-- 
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