错误“Segmentation fault(core dumped)”是什么意思？

Question

i am trying to implement a for-loop using assembler coding and in each iteration the value of the register edi should be printed. When I try to execute my code, I get an Error "Segmentation fault(core dumped)". Can somebody please tell me what does this error mean and are there any mistakes in my code?

section .text
         global _start

_start:
        xor edi,edi

loop:    
        add edi,'0'
        
        ;print i
        mov edi,1
        mov esi,1
        mov ecx,[edi]
        mov edx,1
        syscall
        
        sub edi,'0'
        
        inc edi   
        cmp edi,5
        jl loop

Answer 1

It means that you attempted to access address space in a way that's not permitted. For example:

• you might have tried to write to a read only location

• you might have tried to read from a write only location

• you might have tried to execute code from a location without execute permissions set

• you might have tried to read or write from an address either not mapped at all, or mapped with all kinds of access disallowed

And there are a few more conditions that cause this signal to trip. Have a look at the man pages of mmap and mprotect to get an idea of what's possible.