ELF Object File Format

Question 1

(1) Elf header

Answer 1

Word size, byte ordering, file type (.o, exec, .so), machine type, etc.

ex of some info stored in a header: 64bit, little endian, linux, executable (.out), AMD x86-64, as well as pointers to program header table & address of the entry point

Question 2

(2) segment header table

Answer 2

Page size, virtual addresses memory segments (sections), segment sizes.

This part of ELF is required for executables

Question 3

(3) .text

Answer 3

code. yummy c code. c code yum

Question 4

(4) .rodata

Answer 4

“read only” data section

jump tables, static constants, etc..

Question 5

(5) .data

Answer 5

initialized global vars

Question 6

(6) .bss

Answer 6

Uninitialized global variables
“Block Started by Symbol”
“Better Save Space”
Has section header but occupies no space

Question 7

(7) .symtab

Answer 7

Symbol table
Procedure and static variable names
Section names and locations

Question 8

(8) .rel.text

Answer 8

Relocation info for .text section

Addresses of
instructions that will need to be
modified in the executable

Instructions for modifying.

Question 9

(9) .rel.data

Answer 9

Relocation info for .data section

Addresses of pointer data that will need to be
modified in the merged executable

Question 10

(10) .debug

Answer 10

info for symbolic debugging (gcc -g)

Question 11

(11) section header table

Answer 11

offsets and sizes of each section