I wrote the following (fasm) assembly program:
format ELF64 executable
segment readable executable
; sys_exit, sys_write, strlen and print are from io.inc and
; unistd64.inc at: https://github.com/pbohun/fasm-tutorials
sys_exit = 60
sys_write = 1
entry main
strlen:
push rdi ; push to stack
push rcx ; push to stack
sub rcx, rcx ; set rcx to 0
mov rcx, -1 ; move -1 to rcx
sub al, al ; set al to 0
cld ; clear the direction flags
repne scasb ; repeat if not equal to al
neg rcx ; negate rcx
sub rcx, 1 ; subtract 1 from rcx
mov rax, rcx ; move value from rcx to rax
pop rcx ; restore original rcx value
pop rdi ; restore original rdi value
ret
print:
call strlen ; get string length
mov rdx, rax ; move string length to rdx
mov rsi, rdi ; move address of string to rdi
mov rdi, 1 ; stdout
mov rax, sys_write
syscall
ret
main:
mov rdi, msg
call print
xor rdi, rdi
mov rax, sys_exit
syscall
segment readable
msg db "This is a message.", 0xA, 0
When I disassemble with IDA Pro, under the segments I see this:
My question is, why are both segments called LOAD? What is the meaning behind this? I did not name the segments in my program.
