diff options
Diffstat (limited to 'arch/x86_64/src/context_switching')
| -rw-r--r-- | arch/x86_64/src/context_switching/descriptor_table/global_descriptor_table.cpp | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/arch/x86_64/src/context_switching/descriptor_table/global_descriptor_table.cpp b/arch/x86_64/src/context_switching/descriptor_table/global_descriptor_table.cpp new file mode 100644 index 0000000..1cba13c --- /dev/null +++ b/arch/x86_64/src/context_switching/descriptor_table/global_descriptor_table.cpp @@ -0,0 +1,57 @@ +#include "global_descriptor_table.hpp" + +#include "arch/stl/vector.hpp" + +#include "segment_descriptor.hpp" + +namespace teachos::arch::context_switching::descriptor_table +{ + auto create_global_descriptor_table() -> global_descriptor_table + { + segment_descriptor null_segment{0}; + + // Kernel space code segment + access_byte kernel_code_access_byte{access_byte::PRESENT | access_byte::ACCESS_LEVEL_KERNEL | + access_byte::CODE_OR_DATA_SEGMENT, + type_field::CODE_SEGMENT | type_field::READABLE}; + gdt_flags kernel_code_gdt_flags{gdt_flags::GRANULARITY | gdt_flags::LENGTH}; + segment_descriptor kernel_code_segment{kernel_code_access_byte, kernel_code_gdt_flags, 0, 0xFFFFF}; + + // Kernel space data segment + access_byte kernel_data_access_byte{access_byte::PRESENT | access_byte::ACCESS_LEVEL_KERNEL | + access_byte::CODE_OR_DATA_SEGMENT, + type_field::WRITABLE}; + gdt_flags kernel_data_gdt_flags{gdt_flags::GRANULARITY | gdt_flags::UPPER_BOUND}; + segment_descriptor kernel_data_segment{kernel_data_access_byte, kernel_data_gdt_flags, 0, 0xFFFFF}; + + // User space code segment + access_byte user_code_access_byte{access_byte::PRESENT | access_byte::ACCESS_LEVEL_USER | + access_byte::CODE_OR_DATA_SEGMENT, + type_field::CODE_SEGMENT | type_field::READABLE}; + gdt_flags user_code_gdt_flags{gdt_flags::GRANULARITY | gdt_flags::LENGTH}; + segment_descriptor user_code_segment{user_code_access_byte, user_code_gdt_flags, 0, 0xFFFFF}; + + // User space data segment + access_byte user_data_access_byte{access_byte::PRESENT | access_byte::ACCESS_LEVEL_USER | + access_byte::CODE_OR_DATA_SEGMENT, + type_field::WRITABLE}; + gdt_flags user_data_gdt_flags{gdt_flags::GRANULARITY | gdt_flags::UPPER_BOUND}; + segment_descriptor user_data_segment{user_data_access_byte, user_data_gdt_flags, 0, 0xFFFFF}; + + stl::vector<segment_descriptor> global_descriptor_table{null_segment, kernel_code_segment, kernel_data_segment, + user_code_segment, user_data_segment}; + return global_descriptor_table; + } + + auto load_global_descriptor_table(global_descriptor_table_pointer gdt_pointer) -> void + { + // + } + + auto initialize_global_descriptor_table() -> global_descriptor_table + { + global_descriptor_table gdt{create_global_descriptor_table()}; + global_descriptor_table_pointer gdt_pointer{gdt.size() - 1, &gdt}; + load_global_descriptor_table(gdt_pointer); + } +} // namespace teachos::arch::context_switching::descriptor_table
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