Getting segmentation fault or bus error when moved some code from place before function ret after place just after function call in Assembly

Question

Welcome.

I have following code:

%define ESC 0x1b

section .text
global _start
_start:
.drawer:
    call getdata
    mov rdi, 1
    call sleep
    jmp .drawer
    mov rdi, 0
    mov rax, 60                 ;; sys_exit
    syscall                     ;; exit

sleep:
    mov [timespec.tv_sec], rdi
    xor rdi, rdi
    mov [timespec.tv_usec], rdi
    mov rdi, timespec
    xor rsi, rsi
    mov rax, 35                 ;; sys_nanosleep
    syscall                     ;; nanosleep
    ret

getuptime:
    mov rdx, 16
    mov rsi, data.uptimebuf
    mov rdi, filename.uptime
    call readfile
    mov rdi, rsi
    mov rsi, 0x2e               ;; ASCII '.'
    call strclen
    mov rsi, rax
    call stoin
    mov qword [data.uptime], rax
    mov rdi, qword [data.uptime]
    call printi
    ret

getdata:
    call getuptime
    ret

section .data
data:
    .uptime dq 0
    .uptimebuf times 16 db 0
timespec:
    .tv_sec dq 0
    .tv_usec dq 0

section .rodata
ansi:
    .clear db ESC, "[2J", ESC, "[H"
    .clearlen equ $ - .clear
filename:
    .uptime db "/proc/uptime"

;; Content under this line is included on beginning like this:
;; %include "libasm.asm"
;; under line
;; %define ESC 0x1b

section .text

strlen: ;; string: rdi
    push rbx
    mov rbx, rdi
.again:
    cmp byte [rbx], 0
    jz .done
    inc rbx
    jmp .again
.done:
    sub rbx, rdi
    mov rax, rbx
    pop rbx
    ret

strclen: ;; string: rdi, char: rsi
    push rbx
    mov rbx, rsi
    mov al, bl
    mov rbx, rdi
.again:
    cmp byte [rbx], 0
    jz .done
    cmp byte [rbx], al
    je .done
    inc rbx
    jmp .again
.done:
    sub rbx, rdi
    mov rax, rbx
    pop rbx
    ret

printn: ;; string: rdi, len: rsi
    push rdx
    push rsi
    push rdi
    mov rdx, rsi
    mov rsi, rdi
    mov rdi, 1
    mov rax, 1                  ;; sys_write
    syscall                     ;; write(unsigned int fd, const char *buf, size_t count)
    pop rdi
    pop rsi
    pop rdx
    ret

stoin: ;; string: rdi, len: rsi
    push rdx
    push rcx
    push rbx
    mov rdx, rdi
    xor rcx, rcx
    xor rax, rax
.again:
    mov rbx, 10
    cmp rcx, rsi
    jge .done
    push rdx
    mul rbx
    pop rdx
    xor rbx, rbx
    mov bl, byte [rdx]
    sub bl, 0x30                    ;; ASCII '0'
    add rax, rbx
    inc rdx
    inc rcx
    jmp .again
.done:
    pop rbx
    pop rcx
    pop rdx
    ret

readfile: ;; filename: rdi, buffer: rsi, length: rdx
    push rsi
    xor rsi, rsi
    mov rax, 2                  ;; sys_open
    syscall                     ;; open(char *filename, int flags, int mode)
    pop rsi
    push rdi
    mov rdi, rax
    mov rax, 0                  ;; sys_read
    syscall                     ;; read(unsigned int fd, const char *buf, size_t count)
    mov rax, 3                  ;; sys_close
    syscall                     ;; close(unsigned int fd);
    pop rdi
    ret

printi: ;; long: rdi
    extern printf
    section .data
    fmt db "%ld", 10, 0
    section .text
    push rsi
    mov rsi, rdi
    mov rdi, fmt
    call printf
    pop rsi
    ret

If it stays like that, everyething works properly, but I want to move last 2 instructions before ret in getuptime function to place just after calling getuptime, just like that:

getuptime:
    mov rdx, 16
    mov rsi, data.uptimebuf
    mov rdi, filename.uptime
    call readfile
    mov rdi, rsi
    mov rsi, 0x2e               ;; ASCII '.'
    call strclen
    mov rsi, rax
    call stoin
    mov qword [data.uptime], rax
    ret

getdata:
    call getuptime
    mov rdi, qword [data.uptime]
    call printi
    ret

but when I'll do it, i am getting Segmentation Fault or Bus Error. Why?