Merge branch 'feat_memory_manager' of ssh://gitlab.ost.ch:45022/teachos/kernel into feat_memory_manager

2 files changed, 49 insertions, 16 deletions

diff --git a/arch/x86_64/include/arch/memory/multiboot.hpp b/arch/x86_64/include/arch/memory/multiboot.hpp
index 37b10f0..f6ff480 100644
--- a/arch/x86_64/include/arch/memory/multiboot.hpp
+++ b/arch/x86_64/include/arch/memory/multiboot.hpp
@@ -124,40 +124,43 @@ namespace teachos::arch::memory
       // Nothing to do
     }
 
-    auto writeable() -> bool { return is_bit_set(0); }
+    auto writeable() const -> bool { return is_bit_set(0); }
 
-    auto occupies_memory() -> bool { return is_bit_set(1); }
+    auto occupies_memory() const -> bool { return is_bit_set(1); }
 
-    auto is_executable() -> bool { return is_bit_set(2); }
+    auto is_executable() const -> bool { return is_bit_set(2); }
 
-    auto contains_duplicate_data() -> bool { return is_bit_set(4); }
+    auto contains_duplicate_data() const -> bool { return is_bit_set(4); }
 
-    auto contains_strings() -> bool { return is_bit_set(5); }
+    auto contains_strings() const -> bool { return is_bit_set(5); }
 
-    auto section_header_info_is_section_header_table_index() -> bool { return is_bit_set(6); }
+    auto section_header_info_is_section_header_table_index() const -> bool { return is_bit_set(6); }
 
-    auto preserve_ordering_after_combination() -> bool { return is_bit_set(7); }
+    auto preserve_ordering_after_combination() const -> bool { return is_bit_set(7); }
 
-    auto requires_special_os_processing() -> bool { return is_bit_set(8); }
+    auto requires_special_os_processing() const -> bool { return is_bit_set(8); }
 
-    auto is_section_group_member() -> bool { return is_bit_set(9); }
+    auto is_section_group_member() const -> bool { return is_bit_set(9); }
 
-    auto holds_thread_local_data() -> bool { return is_bit_set(10); }
+    auto holds_thread_local_data() const -> bool { return is_bit_set(10); }
 
-    auto is_compressed() -> bool { return is_bit_set(11); }
+    auto is_compressed() const -> bool { return is_bit_set(11); }
 
-    auto has_special_ordering_requirements() -> bool { return is_bit_set(30); }
+    auto has_special_ordering_requirements() const -> bool { return is_bit_set(30); }
 
-    auto is_excluded_unless_referenced_or_allocated() -> bool { return is_bit_set(31); }
+    auto is_excluded_unless_referenced_or_allocated() const -> bool { return is_bit_set(31); }
+
+    auto operator==(elf_section_flags const & other) const -> bool { return flags == other.flags; }
 
   private:
-    auto is_bit_set(uint8_t index) -> bool { return flags[index] == 1; }
+    auto is_bit_set(uint8_t index) const -> bool { return flags[index] == 1; }
 
     std::bitset<64U> flags;
   };
 
   /**
-   * https://docs.oracle.com/cd/E19455-01/806-3773/elf-2/index.html
+   * @brief Defines the data included in a section header, where each section has exactly one section header.
+   * See https://refspecs.linuxbase.org/elf/gabi4+/ch4.sheader.html for more information
    */
   struct elf_section_header
   {
@@ -171,6 +174,19 @@ namespace teachos::arch::memory
     uint32_t additional_information;
     uint64_t address_alignment;
     uint64_t fixed_table_entry_size;
+
+    /**
+     * @brief Detect whether e section header is inactive or not, should always be the case for the first entry in the
+     * sections table
+     * @return Whether the current section header is actually null or not, requires all fields besides section_size and
+     * other_section to actually contain 0
+     */
+    auto is_null() const -> bool
+    {
+      return name_table_index == 0U && type == elf_section_type::UNSPECIFIED && flags == 0U && virtual_address == 0U &&
+             file_offset == 0U && additional_information == 0U && address_alignment == 0U &&
+             fixed_table_entry_size == 0U;
+    }
   };
 
   /**
diff --git a/arch/x86_64/src/kernel/main.cpp b/arch/x86_64/src/kernel/main.cpp
index 636ddf2..2ba4fe2 100644
--- a/arch/x86_64/src/kernel/main.cpp
+++ b/arch/x86_64/src/kernel/main.cpp
@@ -11,7 +11,12 @@ namespace teachos::arch::kernel
     video::vga::text::write("Assert failed", video::vga::text::common_attributes::green_on_black);
     while (!condition)
     {
-      ;
+      // Trick the compiler into thinking the variable is changes at run time,
+      // to prevent the while loop being optimized away
+      // See
+      // https://stackoverflow.com/questions/9495856/how-to-prevent-g-from-optimizing-out-a-loop-controlled-by-a-variable-that-can
+      // for mroe information.
+      asm volatile("" : "+g"(condition));
     }
   }
 
@@ -44,8 +49,20 @@ namespace teachos::arch::kernel
     constexpr auto actual_entry_size = sizeof(arch::memory::elf_section_header);
     assert(expected_entry_size == actual_entry_size);
 
+    auto expected_total_size = symbol->tag.size;
+    auto actual_total_entry_size = actual_entry_size * symbol->number_of_sections;
+    constexpr auto actual_total_section_size =
+        sizeof(arch::memory::elf_symbols_section) - actual_entry_size - sizeof(uint32_t);
+    auto actual_total_size = actual_total_entry_size + actual_total_section_size;
+    assert(expected_total_size == actual_total_size);
+
     auto begin = &symbol->sections;
     auto end = begin + symbol->number_of_sections;
+    // TODO: Last value is completly wrong, should show 0 but shows huge value for size of entries in the table of the
+    // SHT_NULL elf section entry. Memory around value also make no sense and look even worse? But according to api
+    // value should be zero :(
+    // assert(begin->is_null());
+
     for (auto section = begin; section != end; ++section)
     {
       video::vga::text::write("Looping Code section", video::vga::text::common_attributes::green_on_black);