ELF

Executable and Linking Format. More...

Collaboration diagram for ELF:

Data Structures
struct	elf_program_header_entry_t
	program header entries tell us how to load executables More...
struct	elf_header_t
	The ELF header at the start of every ELF file. More...

Macros
#define	MAGIC_0   0x7F
	magic value expected at the beginning of an ELF file
#define	MAGIC_1   'E'
	magic value expected at the beginning of an ELF file
#define	MAGIC_2   'L'
	magic value expected at the beginning of an ELF file
#define	MAGIC_3   'F'
	magic value expected at the beginning of an ELF file
#define	VERSION   1
	only ELF version 1 is supported (the current version)

Typedefs
typedef elf_header_t	elf_t
	an ELF file starts with the header

Enumerations
enum	elf_class { CLASS_32_BIT = 1, CLASS_64_BIT }
	32 or 64 bit
enum	elf_data { DATA_LITTLE_ENDIAN = 1, DATA_BIG_ENDIAN }
	little or big endian
enum	elf_type { TYPE_RELOCATABLE = 1, TYPE_EXECUTABLE, TYPE_SHARED, TYPE_CORE }
	object type
enum	elf_machine { MACHINE_X86 = 3 }
	targeted ISA, we are only interested in x86

Functions
static uint8_t	elf_check (elf_t *elf)
	Checks whether a pointer points to a valid ELF file for this OS. More...
void *	elf_load (elf_t *elf, page_directory_t *page_directory)
	Loads the segments of an ELF file into memory. More...
void	elf_unload (elf_t *elf, page_directory_t *page_directory)
	Frees the segments of an ELF file in memory. More...
task_pid_t	elf_create_task (elf_t *elf, size_t kernel_stack_len, size_t user_stack_len)
	Creates a user task running the code of an ELF file. More...
void	elf_destroy_task (task_pid_t pid)
	Destroys a user task running the code of an ELF file. More...

Detailed Description

Executable and Linking Format.

ELF files are used to execute external programs in user space.

See also

https://en.wikipedia.org/wiki/Executable_and_Linkable_Format

http://wiki.osdev.org/ELF

http://lowlevel.eu/wiki/ELF

http://www.linux-kernel.de/appendix/ap05.pdf

Function Documentation

static uint8_t elf_check ( elf_t *  elf )

static

Checks whether a pointer points to a valid ELF file for this OS.

Parameters

elf	the start address of the ELF file in memory

Returns

whether it is a valid ELF file

Definition at line 56 of file elf.c.

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task_pid_t elf_create_task	(	elf_t *	elf,
		size_t	kernel_stack_len,
		size_t	user_stack_len
	)

Creates a user task running the code of an ELF file.

Parameters

elf	the start address of the ELF file in memory
kernel_stack_len	number of bytes to allocate for the kernel stack
user_stack_len	number of bytes to allocate for the user stack

Returns

PID of the created ELF task

Definition at line 148 of file elf.c.

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void elf_destroy_task

(

task_pid_t

pid

)

Destroys a user task running the code of an ELF file.

Parameters

pid	PID of the ELF task

Definition at line 166 of file elf.c.

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void* elf_load	(	elf_t *	elf,
		page_directory_t *	page_directory
	)

Loads the segments of an ELF file into memory.

Parameters

elf	the start address of the ELF file in memory
page_directory	a page directory to map the segments into

Returns

the entry point as a virtual address

Definition at line 91 of file elf.c.

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void elf_unload	(	elf_t *	elf,
		page_directory_t *	page_directory
	)

Frees the segments of an ELF file in memory.

Parameters

elf	the start address of the ELF file in memory
page_directory	a page directory to unmap the segments from

Definition at line 127 of file elf.c.

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