Check If Two String Arrays are Equivalent ASM solution

global _start
section .text
_start:
    lea rdi, [str1]
    call str_len
    mov edx, eax
    lea rdi, [str2]
    call str_len
    mov ebx, eax
    cmp edx, ebx
    jne _errlen
    call _cmp_str
    mov rbx, rax
    call check_equal
    jmp _exit

check_equal:
    cmp rax, 1
    je _CE2
_CE1:
    mov rsi, truemsg
    mov rdx, 5
    jmp _CE3
_CE2: ; false state
    mov rsi, falsemsg
    mov rdx, 6
_CE3:
    mov rax, 1
    mov rdi, 1
    syscall
    ret

str_len:
    mov eax, 0
    test rdi, rdi
    jne _S2
_S4:
    add rax, 1
_S2:
    cmp byte [rdi + rax], 0
    jne _S4
    ret

_errlen:
    mov rax, 1
    mov rdi, 1
    mov rsi, err
    mov rdx, 21
    syscall

_exit:
    mov rax, 60
    xor rdi, rdi
    syscall
    nop
    nop
    nop
_cmp_str:
    mov rcx, rdx
    test rcx, rcx
    lea rdi, [str1]
    lea rsi, [str2]
_L1:
    movdqu  xmm0, [rdi]
    movdqu  xmm1, [rsi]
    mov    eax, ecx
    mov    edx, ecx
    pcmpestrm xmm0, xmm1, 0b11000 ; _SIDD_UBYTE_OPS | _SIDD_CMP_EQUAL_EACH | _SIDD_NEGATIVE_POLARITY | _SIDD_LEAST_SIGNIFICANT
    setb   al
    movzx  eax, al
    jb _L2
    cmp rcx, 16
    ja _L3
_L4:
    ret
_L3:
    sub     rcx, 16
    add     rdi, 16
    add     rsi, 16
    jmp _L1
_L2:
    nop
    mov eax, 1
    ret


section .data
err: db "length doesn't match", 10, 0
truemsg: db "true", 10, 0
falsemsg: db "false", 10, 0

align   16
str1: db "abc", "d", "defg", 0
str2: db "abcddefg", 0