From a20045fb209edc1e338039c28634c942e3113ea4 Mon Sep 17 00:00:00 2001
From: Lukas Oesch <lukasoesch20@gmail.com>
Date: Mon, 16 Mar 2026 21:06:12 +0100
Subject: Protect boot modules in region_allocator

---
 arch/x86_64/src/memory/region_allocator.cpp | 43 +++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 11 deletions(-)

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

diff --git a/arch/x86_64/src/memory/region_allocator.cpp b/arch/x86_64/src/memory/region_allocator.cpp
index facb1f2..2690a7c 100644
--- a/arch/x86_64/src/memory/region_allocator.cpp
+++ b/arch/x86_64/src/memory/region_allocator.cpp
@@ -35,7 +35,7 @@ namespace arch::memory
       , m_kernel_end{kapi::memory::frame::containing(mem_info.image_range.second)}
       , m_multiboot_start{kapi::memory::frame::containing(mem_info.mbi_range.first)}
       , m_multiboot_end{kapi::memory::frame::containing(mem_info.mbi_range.second)}
-  // TODO BA-FS26: Protect MB2 boot modules
+      , m_multiboot_information{mem_info.mbi}
   {
     choose_next_region();
   }
@@ -76,19 +76,40 @@ namespace arch::memory
       }
     }
 
-    if (falls_within(m_next_frame, m_kernel_start, m_kernel_end))
+    auto advanced = true;
+    while (advanced)
     {
-      m_next_frame = m_kernel_end + 1;
-    }
+      advanced = false;
 
-    if (falls_within(m_next_frame, m_multiboot_start, m_multiboot_end))
-    {
-      m_next_frame = m_multiboot_end + 1;
-    }
+      if (falls_within(m_next_frame, m_kernel_start, m_kernel_end))
+      {
+        m_next_frame = m_kernel_end + 1;
+        advanced = true;
+        break;
+      }
 
-    if (falls_within(m_next_frame, m_kernel_start, m_kernel_end))
-    {
-      m_next_frame = m_kernel_end + 1;
+      if (falls_within(m_next_frame, m_multiboot_start, m_multiboot_end))
+      {
+        m_next_frame = m_multiboot_end + 1;
+        advanced = true;
+        break;
+      }
+
+      if (m_multiboot_information)
+      {
+        for (auto const & module : m_multiboot_information->modules())
+        {
+          auto module_start = kapi::memory::frame::containing(kapi::memory::physical_address{module.start_address});
+          auto module_end = kapi::memory::frame::containing(kapi::memory::physical_address{module.end_address});
+
+          if (falls_within(m_next_frame, module_start, module_end))
+          {
+            m_next_frame = module_end + 1;
+            advanced = true;
+            break;
+          }
+        }
+      }
     }
 
     if (m_next_frame > last_frame(*m_current_region))
-- 
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