From 0b62fdb3fe657d056a42d7567b67951ba3468738 Mon Sep 17 00:00:00 2001
From: Fabian Imhof <fabian.imhof@ost.ch>
Date: Thu, 8 May 2025 08:51:52 +0000
Subject: wip allocating heap memory in user mode

---
 .../arch/memory/heap/global_heap_allocator.hpp     |  7 +++-
 .../arch/memory/heap/user_heap_allocator.hpp       | 48 ++++++++++++++++++++++
 .../include/arch/memory/paging/kernel_mapper.hpp   |  2 +-
 3 files changed, 54 insertions(+), 3 deletions(-)
 create mode 100644 arch/x86_64/include/arch/memory/heap/user_heap_allocator.hpp

(limited to 'arch/x86_64/include')

diff --git a/arch/x86_64/include/arch/memory/heap/global_heap_allocator.hpp b/arch/x86_64/include/arch/memory/heap/global_heap_allocator.hpp
index bfc7b67..d0d1080 100644
--- a/arch/x86_64/include/arch/memory/heap/global_heap_allocator.hpp
+++ b/arch/x86_64/include/arch/memory/heap/global_heap_allocator.hpp
@@ -2,6 +2,7 @@
 #define TEACHOS_ARCH_X86_64_MEMORY_HEAP_GLOBAL_HEAP_ALLOCATOR_HPP
 
 #include "arch/memory/heap/heap_allocator.hpp"
+#include "arch/memory/heap/user_heap_allocator.hpp"
 
 namespace teachos::arch::memory::heap
 {
@@ -76,7 +77,8 @@ namespace teachos::arch::memory::heap
 
   private:
     static heap_allocator * kernel_allocator_instance;  ///< Instance used to allocate and deallocate kernel heap memory
-    static heap_allocator * user_allocator_instance;    ///< Instance used to allocate and deallocate user heap memory
+    static user_heap_allocator *
+        user_allocator_instance;  ///< Instance used to allocate and deallocate user heap memory
 
     /**
      * @brief Either returns the previously registered heap allocated or halts further execution
@@ -90,7 +92,8 @@ namespace teachos::arch::memory::heap
      *
      * @return Reference to the registered user heap allocation
      */
-    static auto user() -> heap_allocator &;
+    [[gnu::section(".user_text")]]
+    static auto user() -> user_heap_allocator &;
   };
 }  // namespace teachos::arch::memory::heap
 
diff --git a/arch/x86_64/include/arch/memory/heap/user_heap_allocator.hpp b/arch/x86_64/include/arch/memory/heap/user_heap_allocator.hpp
new file mode 100644
index 0000000..1dab047
--- /dev/null
+++ b/arch/x86_64/include/arch/memory/heap/user_heap_allocator.hpp
@@ -0,0 +1,48 @@
+#ifndef TEACHOS_ARCH_X86_64_MEMORY_HEAP_USER_HEAP_ALLOCATOR_HPP
+#define TEACHOS_ARCH_X86_64_MEMORY_HEAP_USER_HEAP_ALLOCATOR_HPP
+
+#include "arch/memory/heap/heap_allocator.hpp"
+
+#include <atomic>
+#include <cstdint>
+
+namespace teachos::arch::memory::heap
+{
+  /**
+   * @brief Simple heap allocator, which allocates linearly and leaks all allocated memory, because it does not really
+   * deallocate anything.
+   */
+  struct user_heap_allocator
+  {
+    /**
+     * @brief Constructor.
+     *
+     * @param heap_start Start of the allocatable heap area
+     * @param heap_end End of the allocatable heap area (Start + Size)
+     */
+    user_heap_allocator(std::size_t heap_start, std::size_t heap_end)
+        : heap_start{heap_start}
+        , heap_end{heap_end}
+        , next{heap_start}
+    {
+      // Nothing to do
+    }
+
+    auto allocate(std::size_t size) -> void *;
+
+    /**
+     * @copybrief heap_allocator::deallocate
+     *
+     * @note Simply does nothing, because this allocator leaks all memory
+     */
+    auto deallocate(void * pointer) noexcept -> void;
+
+  private:
+    std::size_t heap_start;     ///< Start of the allocatable heap area
+    std::size_t heap_end;       ///< End of the allocatable heap area
+    std::atomic_uint64_t next;  ///< Current address, which is the start of still unused allocatable heap area
+  };
+
+}  // namespace teachos::arch::memory::heap
+
+#endif  // TEACHOS_ARCH_X86_64_MEMORY_HEAP_USER_HEAP_ALLOCATOR_HPP
diff --git a/arch/x86_64/include/arch/memory/paging/kernel_mapper.hpp b/arch/x86_64/include/arch/memory/paging/kernel_mapper.hpp
index ce74b98..6459107 100644
--- a/arch/x86_64/include/arch/memory/paging/kernel_mapper.hpp
+++ b/arch/x86_64/include/arch/memory/paging/kernel_mapper.hpp
@@ -143,7 +143,7 @@ namespace teachos::arch::memory::paging
         // statically allocated variables), .boot_rodata (Contains constant data stored in ROM)
         // Not required: .text, .rodata, .ctors, .dtors, .bss, .data, .boot_data, .boot_text, .init
         if (section.physical_address == 0x100000 || section.physical_address == 0x102000 ||
-            section.physical_address == 0x216000)
+            section.physical_address == 0x217000)
         {
           entry.set_user_accesible();
         }
-- 
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