code: def sys_arch_prctl(self, code, addr):
          
          ARCH_SET_GS = 0x1001
          ARCH_SET_FS = 0x1002
          ARCH_GET_FS = 0x1003
          ARCH_GET_GS = 0x1004
          if code not in {ARCH_SET_GS, ARCH_SET_FS, ARCH_GET_FS, ARCH_GET_GS}:
              logger.debug("code not in expected options ARCH_GET/SET_FS/GS")
              return -errno.EINVAL
          if code != ARCH_SET_FS:
              raise NotImplementedError("Manticore supports only arch_prctl with code=ARCH_SET_FS (0x1002) for now")
          self.current.FS = 0x63
          self.current.set_descriptor(self.current.FS, addr, 0x4000, 'rw')
          return 0
docs: Sets architecture-specific thread state
          :rtype: int
  
          :param code: must be C{ARCH_SET_FS}.
          :param addr: the base address of the FS segment.
          :return: C{0} on success
          :raises error:
              - if C{code} is different to C{ARCH_SET_FS}