From 5449acc193f96d2ffaeb224aad5cea16bf753cdb Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Thu, 10 Sep 2026 08:53:57 +0200
Subject: x86_64: replace raw pointers with observer_ptr

---
 arch/x86_64/kapi/memory.cpp | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

(limited to 'arch/x86_64/kapi')

diff --git a/arch/x86_64/kapi/memory.cpp b/arch/x86_64/kapi/memory.cpp
index 03c5107c..307789cd 100644
--- a/arch/x86_64/kapi/memory.cpp
+++ b/arch/x86_64/kapi/memory.cpp
@@ -12,6 +12,7 @@
 #include <kapi/boot.hpp>
 #include <kapi/system.hpp>
 
+#include <kstd/memory.hpp>
 #include <kstd/print.hpp>
 #include <kstd/units.hpp>
 
@@ -49,7 +50,7 @@ namespace kapi::memory
       }
 
       auto const & mbi = boot::bootstrap_information.mbi;
-      auto mbi_span = std::span{std::bit_cast<std::byte *>(mbi), static_cast<std::size_t>(mbi->size())};
+      auto mbi_span = std::span{reinterpret_cast<std::byte const *>(mbi.get()), static_cast<std::size_t>(mbi->size())};
       auto image_span = std::span{&arch::boot::_start_physical, &arch::boot::_end_physical};
 
       return arch::memory::region_allocator::memory_information{
@@ -62,6 +63,9 @@ namespace kapi::memory
 
     auto establish_higher_half_direct_mapping() -> void
     {
+      // We can't use an observer_ptr here, since this first frame allocation is very likely to return frame number
+      // zero, which has a starting address of zero. observer_ptr will interpret this as being a nullptr and raise a
+      // panic on dereference.
       auto pml3_frame = kapi::memory::allocate_frame();
       auto pml3 = static_cast<arch::memory::page_table *>(pml3_frame->start_address());
       pml3->clear();
@@ -75,7 +79,7 @@ namespace kapi::memory
       });
 
       auto current_cr3 = arch::cpu::cr3::read();
-      auto pml4 = static_cast<arch::memory::page_table *>(current_cr3.address());
+      auto pml4 = static_cast<kstd::observer_ptr<arch::memory::page_table>>(current_cr3.address());
       (*pml4)[256].frame(*pml3_frame, arch::memory::page_table::entry::flags::present |
                                           arch::memory::page_table::entry::flags::writable |
                                           arch::memory::page_table::entry::flags::global);
@@ -218,7 +222,7 @@ namespace kapi::memory
       system::panic("[ARCH:MEM] Failed to allocate new PML4!");
     }
     auto new_pml4 = arch::memory::to_higher_half_pointer<arch::memory::page_table>(new_pml4_frame->start_address());
-    std::construct_at(new_pml4);
+    std::construct_at(new_pml4.get());
 
     higher_half_mapper.emplace(new_pml4);
     set_page_mapper(*higher_half_mapper);
@@ -229,7 +233,7 @@ namespace kapi::memory
     remap_bootloader_modules(*higher_half_mapper);
 
     auto current_cr3 = arch::cpu::cr3::read();
-    auto old_pml4 = static_cast<arch::memory::page_table *>(current_cr3.address());
+    auto old_pml4 = static_cast<kstd::observer_ptr<arch::memory::page_table>>(current_cr3.address());
     (*new_pml4)[256] = (*old_pml4)[256];
 
     kstd::println("[ARCH:MEM] Switching to new paging hierarchy.");
-- 
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