汇编语言中的简单代码

Question

I am new to assembly language using the Raspberry Pi. I tried to run this simple program on a Raspberry Pi 3(ARM 8086). It does not cause an error but when I try to see the result in a terminal after compiling and running as _o example.o example.s , gcc _o example examle.s and ./example . the execution result is segmentation fault, can you help me please?

.align 2
    .text
    .global main
main:
    stmfd r13!, {r14}

    mov r0,#1
    bl print

    mov r0,#2
    bl print

    mov r0,#3
    bl print

    ldmfd r13!,{pc} @ return to OS

print:
    stmfd r13!, {r0-r3,r12,r14}
    mov r1,r0
    ldr r0, =num_str
    bl printf
    ldmfd r13!, {r0-r3,r12,pc}

.data

    .align 2
num_str:
    .asciz “%d\n”
.end

Answer 1

The ABI requires that the stack pointer is aligned to multiple of 8 bytes, your main function decrements the stack pointer by 4 making it unaligned. Presumably printf uses an instruction that requires 8 byte alignment.