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docs: documented ELF loading / segment mapping

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antifallobst 2023-03-02 19:07:30 +01:00
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@ -299,12 +299,14 @@ More information can be found on the limine project's [GitHub](https://github.co
#### `elf_executable_T` - struct #### `elf_executable_T` - struct
This struct holds the parsed data of an ELF executable. This struct holds the parsed data of an ELF executable.
| Name | Type | Description | | Name | Type | Description |
|--------------|--------------|----------------------------------------------------------------------------------------------------------------------------------| |--------------|----------------|----------------------------------------------------------------------------------------------------------------------------------|
| header | elf_header_T | The header of the elf file | | header | elf_header_T | The header of the elf file |
| num_symbols | uint64_t | The size of _symbols_ | | num_symbols | uint64_t | The size of _symbols_ |
| symbols | symbol_T* | An array containing all symbols of the elf file | | symbols | symbol_T* | An array containing all symbols of the elf file |
| string_table | void* | A copy of the elf files `.strtab` section, all strings are referenced here to have them available even if the elf file is closed | | num_mappings | uint64_t | The size of _mappings_ |
| mappings | elf_mapping_T* | An array containing the mappings needed to load the elf file |
| string_table | void* | A copy of the elf files `.strtab` section, all strings are referenced here to have them available even if the elf file is closed |
#### `elf_executable_temp_T` - struct #### `elf_executable_temp_T` - struct
This struct is used while generating an `elf_executable_T`. This struct is used while generating an `elf_executable_T`.
@ -384,6 +386,22 @@ Holds the parsed kernel executable.
This will be removed, when processes are implemented, because then this can be accessed via the kernel process control struct. This will be removed, when processes are implemented, because then this can be accessed via the kernel process control struct.
### elf/mapping.h
#### `elf_mapping_T` - struct
A mapping describes an area of memory,
that should be copied from the elf file into the RAM and how/where it should be mapped.
| Name | Type | Description |
|----------------|----------|------------------------------------------------------------------------------------------------------------------|
| offset_file | uint64_t | The mappings' start in the elf file |
| offset_virtual | uint64_t | The mappings' start in memory |
| length_file | uint64_t | The mappings' size in the elf file |
| length_virtual | uint64_t | The mappings' size in memory, if this is bigger than _length_file_ the remaining space will be filled with zeros |
#### `elf_mappings_apply(mappings, num_mappings, buffer, base, page_map)` - function (void)
Maps all **_mappings_** into **_page_map_** and copies the related data from **_buffer_** (elf file) to the mapped memory.
**_base_** specifies where the mappings should start in the virtual address space.
### elf/section.h ### elf/section.h
#### `elf_section_type_E` - enum #### `elf_section_type_E` - enum
- **Null** - These sections can be ignored - **Null** - These sections can be ignored
@ -415,6 +433,32 @@ This will be removed, when processes are implemented, because then this can be a
#### `g_elf_section_type_strings` - global variable #### `g_elf_section_type_strings` - global variable
An array of strings matching `elf_section_type_E`. An array of strings matching `elf_section_type_E`.
### elf/segment.h
#### `elf_segment_type_E` - enum
- **Null** - Unused segment
- **Load** - Segment that should be included into mappings
- **Dynamic** - Segments of this type contain dynamic linking information
- **Interpreter** - This holds a path to an interpreter
- **Note** - These segments hold notes by the compiler / toolchain
- **Program Header Table** - This points to the table that is holding the segment headers
- **TLS** - This holds a Thread Local Storage template
#### `elf_segment_T` - struct
| Name | Type | Description |
|------------------|----------|-----------------------------------------------------------------|
| type | uint32_t | The segments type -> `elf_segment_type_E` |
| flags | uint32_t | The segments flags (Read / Write / Execute) |
| offset | uint64_t | The segments position in the elf file |
| address_virtual | uint64_t | Where the segment should be mapped in the virtual address space |
| address_physical | uint64_t | Not used in the `System V` ABI |
| length_file | uint64_t | The segments size in the file |
| length_memory | uint64_t | The size of the area that should be mapped for the segment |
| align | uint64_t | The segments alignment (has to be a power of 2) |
#### `g_elf_segment_type_strings` - global variable
An array of strings matching `elf_segment_type_E`.
### elf/symbol.h ### elf/symbol.h
#### `ELF_SYMBOL_TYPE(info)` - macro #### `ELF_SYMBOL_TYPE(info)` - macro
Extracts the `elf_symbol_type_E` from the symbols info value. Extracts the `elf_symbol_type_E` from the symbols info value.