kapi: extract page_mapper interface

1 files changed, 43 insertions, 9 deletions

diff --git a/arch/x86_64/src/memory/paging_root.cpp b/arch/x86_64/src/memory/paging_root.cpp
index 5ca2bf0..c458093 100644
--- a/arch/x86_64/src/memory/paging_root.cpp
+++ b/arch/x86_64/src/memory/paging_root.cpp
@@ -27,16 +27,15 @@ namespace teachos::memory::x86_64
     //! still enforcing non-writability and non-execution of the affected page.
     template<std::size_t Level>
       requires(Level > 1uz && Level < 5uz)
-    auto do_map(recursive_page_table<Level> * pml, page page, page_table::entry::flags flags,
-                frame_allocator & allocator)
+    auto do_map(recursive_page_table<Level> * pml, page page, page_table::entry::flags flags)
     {
       auto index = pml_index<Level>(page);
       flags = flags & ~page_table::entry::flags::no_execute;
       flags = flags | page_table::entry::flags::writable;
       if (!(*pml)[index].present())
       {
-        auto new_table_frame = allocator.allocate();
-        auto mapping = scoped_mapping{page, allocator};
+        auto new_table_frame = active_allocator().allocate();
+        auto mapping = scoped_mapping{page};
         (*pml)[index].frame(new_table_frame.value(), page_table::entry::flags::present | flags);
         auto new_table = std::optional{std::construct_at(*pml->next(index))};
         return new_table;
@@ -114,14 +113,49 @@ namespace teachos::memory::x86_64
         .or_else(handle_huge_page);
   }
 
-  auto paging_root::map(page page, frame frame, page_table::entry::flags flags, frame_allocator & allocator)
-      -> std::optional<std::byte *>
+  auto paging_root::map(page page, frame frame, page_table::entry::flags flags) -> std::optional<std::byte *>
   {
     return std::optional{this}
-        .and_then([&](auto pml) -> auto { return do_map(pml, page, flags, allocator); })
-        .and_then([&](auto pml) -> auto { return do_map(pml, page, flags, allocator); })
-        .and_then([&](auto pml) -> auto { return do_map(pml, page, flags, allocator); })
+        .and_then([&](auto pml) -> auto { return do_map(pml, page, flags); })
+        .and_then([&](auto pml) -> auto { return do_map(pml, page, flags); })
+        .and_then([&](auto pml) -> auto { return do_map(pml, page, flags); })
         .and_then([&](auto pml) -> auto { return do_map(pml, page, frame, flags); });
   }
 
+  auto paging_root::unmap(page page) -> void
+  {
+    if (!this->translate(page))
+    {
+      system::panic("[x86_64:MEM] Tried to unmap a page that was not mapped.");
+    }
+
+    auto pml4 = this;
+    auto pml3 = pml4->next(pml_index<4>(page)).value();
+    auto pml2 = pml3->next(pml_index<3>(page)).value();
+    auto pml1 = pml2->next(pml_index<2>(page)).value();
+
+    (*pml1)[pml_index<1>(page)].clear();
+
+    if (pml1->empty())
+    {
+      auto pml1_frame = (*pml2)[pml_index<2>(page)].frame().value();
+      active_allocator().release(pml1_frame);
+      (*pml2)[pml_index<2>(page)].clear();
+    }
+
+    if (pml2->empty())
+    {
+      auto pml2_frame = (*pml3)[pml_index<3>(page)].frame().value();
+      active_allocator().release(pml2_frame);
+      (*pml3)[pml_index<3>(page)].clear();
+    }
+
+    if (pml3->empty())
+    {
+      auto pml3_frame = (*pml4)[pml_index<4>(page)].frame().value();
+      active_allocator().release(pml3_frame);
+      (*pml4)[pml_index<4>(page)].clear();
+    }
+  }
+
 }  // namespace teachos::memory::x86_64
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