From e44a16e45a309aa96375a2215d0d2405cf467dae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matteo=20Gm=C3=BCr?= <matteo.gmuer1@ost.ch>
Date: Sat, 26 Oct 2024 07:37:50 +0000
Subject: Use construct at to zero memory before using it.

---
 arch/x86_64/src/memory/paging/page_mapper.cpp | 11 ++---------
 arch/x86_64/src/memory/paging/page_table.cpp  | 15 +++++++++++----
 2 files changed, 13 insertions(+), 13 deletions(-)

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

diff --git a/arch/x86_64/src/memory/paging/page_mapper.cpp b/arch/x86_64/src/memory/paging/page_mapper.cpp
index 687bffd..cd77366 100644
--- a/arch/x86_64/src/memory/paging/page_mapper.cpp
+++ b/arch/x86_64/src/memory/paging/page_mapper.cpp
@@ -4,17 +4,10 @@
 
 namespace teachos::arch::memory::paging
 {
-  namespace
-  {
-    constexpr size_t PAGE_TABLE_LEVEL_4_ADDRESS = 0xfffffffffffff000;
-  }  // namespace
-
   auto create_or_get() -> page_table_handle
   {
-    // Perhaps we need to access boot::page_map_level_4; so we do not crash when returning entry?
-    static page_table * const active_page = reinterpret_cast<page_table *>(PAGE_TABLE_LEVEL_4_ADDRESS);
-    // We can not save page_table_handle as a static variable directly, if we do the program will fail to link.
-    return page_table_handle{active_page, page_table_handle::LEVEL4};
+    // TODO: As soon as linker error is fixed in toolchain make handle static and return that.
+    return page_table_handle{arch::boot::page_map_level_4, page_table_handle::LEVEL4};
   }
 
   auto translate_page(virtual_page page) -> std::optional<allocator::physical_frame>
diff --git a/arch/x86_64/src/memory/paging/page_table.cpp b/arch/x86_64/src/memory/paging/page_table.cpp
index 1d7b8a0..2f97a80 100644
--- a/arch/x86_64/src/memory/paging/page_table.cpp
+++ b/arch/x86_64/src/memory/paging/page_table.cpp
@@ -1,6 +1,7 @@
 #include "arch/memory/paging/page_table.hpp"
 
 #include <array>
+#include <memory>
 
 namespace teachos::arch::memory::paging
 {
@@ -9,6 +10,11 @@ namespace teachos::arch::memory::paging
    */
   struct page_table
   {
+    /**
+     * @brief Defaulted constructor.
+     */
+    page_table() = default;
+
     /**
      * @brief Set every entry of the page to unused.
      */
@@ -46,9 +52,9 @@ namespace teachos::arch::memory::paging
      */
     auto next_table_address(std::size_t table_index) -> std::optional<std::size_t>;
 
-    std::array<entry, PAGE_TABLE_ENTRY_COUNT>
-        entries{};  ///< Entries containing addresses to page tables of a level below or
-                    ///< actual virtual addresses for the level 1 page table.
+    std::array<entry, PAGE_TABLE_ENTRY_COUNT> entries =
+        {};  ///< Entries containing addresses to page tables of a level below or
+             ///< actual virtual addresses for the level 1 page table.
   };
 
   auto page_table::zero_entries() -> void
@@ -67,7 +73,8 @@ namespace teachos::arch::memory::paging
     auto address = next_table_address(table_index);
     if (address)
     {
-      return reinterpret_cast<page_table *>(address.value());
+      // TODO: Probably erases the data even if the page table already existed previously and had values.
+      return std::construct_at(reinterpret_cast<page_table *>(address.value()));
     }
     return std::nullopt;
   }
-- 
cgit v1.2.3