From be86be1facfce8fe3f376153b9c582f2c5c026aa Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Tue, 2 Dec 2025 12:31:53 +0100
Subject: x86_64/memory: extend scoped_mapping

---
 arch/x86_64/src/memory/paging_root.cpp    | 41 +++++++++++++++++++++++++++++++
 arch/x86_64/src/memory/scoped_mapping.cpp |  8 +++++-
 2 files changed, 48 insertions(+), 1 deletion(-)

(limited to 'arch/x86_64/src')

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()
   {
-- 
cgit v1.2.3