assembly - Why does returning from _start segfault?

Question

I tried to put code not in the main function, but directly into _start:

    segment .text
    global _start
_start:
    push rbp
    mov rbp, rsp
    ; ... program logic ...
    leave
    ret

Compile:

yasm -f elf64 main.s
ld -o main main.o

Run:

./main
Segmentation fault(core dumped)

I read, leave is

mov esp,ebp
pop ebp

But why is it that such an epilogue to the pop stack frame and the set base frame pointer to a previous frame's base results in a segmentation fault?

Indeed, making an exit system call exits gracefully.

Answer 1

As per ABI¹ the stack at the entry on _start is

There is no "return address".
The only way to exit a process is through SYS_EXIT

xorl %edi, %edi   ;Error code
movl $60, %eax    ;SYS_EXIT
syscall

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¹ Section 3.4.1 Initial Stack and Register State.