Add is empty check method for page table

2 files changed, 15 insertions, 2 deletions

diff --git a/arch/x86_64/include/arch/memory/paging/page_mapper.hpp b/arch/x86_64/include/arch/memory/paging/page_mapper.hpp
index d852fbc..6a0c989 100644
--- a/arch/x86_64/include/arch/memory/paging/page_mapper.hpp
+++ b/arch/x86_64/include/arch/memory/paging/page_mapper.hpp
@@ -146,10 +146,10 @@ namespace teachos::arch::memory::paging
     exception_handling::assert(level1_frame.has_value(),
                                "[Page Mapper] Attempted to unmap page, which has not been mapped previously");
     level1_entry.set_unused();
-    invalidate_page_cache(&level1_entry);
     // TODO: Deallocate and unmap level 1, 2, 3 page table entry if this was the last page in them.
     // TODO: Fix deallocate because it is not yet implemented.
     allocator.deallocate_frame(level1_frame.value());
+    invalidate_page_cache(&level1_entry);
   }
 }  // namespace teachos::arch::memory::paging
 
diff --git a/arch/x86_64/include/arch/memory/paging/page_table.hpp b/arch/x86_64/include/arch/memory/paging/page_table.hpp
index e4847e3..07e7e22 100644
--- a/arch/x86_64/include/arch/memory/paging/page_table.hpp
+++ b/arch/x86_64/include/arch/memory/paging/page_table.hpp
@@ -57,6 +57,11 @@ namespace teachos::arch::memory::paging
     auto zero_entries() -> void;
 
     /**
+     * @brief Checks if all entries of this page are unused.
+     */
+    auto is_empty() const -> bool;
+
+    /**
      * @brief Returns the next page table level from the given page table index. Meaning we
      * use an index into a Level 4 page table to get the according Level 3 page table.
      *
@@ -97,7 +102,7 @@ namespace teachos::arch::memory::paging
     }
 
     /**
-     * @brief Index operator overload to access specific immutable entry directy.
+     * @brief Index operator overload to access specific mutable entry directy.
      *
      * @param index Index of the entry we want to access and only read.
      * @return Entry at the given table index.
@@ -105,6 +110,14 @@ namespace teachos::arch::memory::paging
     auto operator[](std::size_t index) -> entry &;
 
     /**
+     * @brief Index operator overload to access specific immutable entry directy.
+     *
+     * @param index Index of the entry we want to access and read or write.
+     * @return Entry at the given table index.
+     */
+    auto operator[](std::size_t index) const -> entry const &;
+
+    /**
      * @brief Decrements the page table handle level enum by one, is defined so we can use it as a replacement for an
      * int index in a range based for loop.
      *