How to return to main after jump?

Question

Well, I have this code:

SECTION .data
    message: db "Value = %d", 10, 0
    message2: db "End", 10, 0
SECTION .bss

SECTION .text

extern printf
global main

main:
    push ebp
    mov ebp, esp

    mov ebx, 0
    jmp loop
    push message2
    call printf
    mov esp, ebp
    pop ebp
    ret

loop: 
    push ebx 
    push message 
    call printf 
    inc ebx 
    cmp ebx, 100000
    jne loop 
    mov esp, ebp
    pop ebp

I would like know how to return back to main and then print message2?

Thanks for helps and sorry for my english.

Answer 1

Problem is that you are calling C-function that uses cdecl calling convention (caller must clean the stack). This means that after the call, you must add the size of the arguments (in bytes) to the stackpointer. Your first printf takes 2 dword arguments (8 bytes) so you must add 8 to stackpointer after the call. Your second call passes one dword so you add 4 to the stackpointer.

This should work:

SECTION .data
        message: db "Value = %d", 10, 0
        message2: db "End", 10, 0
SECTION .bss

SECTION .text

extern printf
global main

main:
        push ebp
        mov ebp, esp

        mov ebx, 0
        call loop
        push message2
        call printf
        add esp, 4
        mov esp, ebp
        pop ebp
        ret

loop:
        push ebx
        push message
        call printf
        add esp, 8
        inc ebx
        cmp ebx, 10000
        jne loop
        ret

Answer 2

Probably not enough ranking to add as a comment...

push return address before jmp

see this: Substitutes for x86 assembly 'call' instruction?

Answer 3

try it this way:

SECTION .data

message: db "Value = %d", 10, 0

message2: db "End", 10, 0

SECTION .bss

SECTION .text

extern printf global main

main:

push ebp
mov ebp, esp

mov ebx, 0
call loop

push message2
call printf

mov esp, ebp
pop ebp
ret

loop:

push ebx
push message
call printf 
inc ebx 
cmp ebx, 100000
jne loop 

ret