Linux build and print

Question

I am trying to write a simple build of a program with the printf function. I will compile it nasm -f elf 64 and the link using gcc . After starting, I see a segmentation fault . What's wrong?

 [Bits 32] extern printf global main section .data hello: db "Hello", 0xa, 0 section .text main: push hello call [printf] add esp, 4 mov eax, 1 mov ebx, 0 int 80h 

Answer 1

Linux on ia32 does not use the same calling convention as on amd64. Since your code uses the first, you should compile it as 32 bits and associate it with a 32-bit libc. On debian, you'll need the libc6-dev-i386 package.

You should also replace 'call [printf]' with 'call printf', which is an error.

Please also note that when using the main interface, you must return from the main interface and not make a system call to exit to allow C start-up code to run.

Hello World example for x86-32 with assembly instructions .

If you are working on amd64, you can learn how to write a 64-bit assembly.

Hello World example for x86-64 with assembly instructions .

Answer 2

If you really want to get a 32-bit binary, as the title of your code shows, you just need to fix the line:

 call [printf] 

changing it to:

 call printf 

When you execute call [printf] , you do not call printf, and the address indicated by the first byte of the printf code, this construct ( [address] ) is called the effective address .