ARCH_SET_FS
return do_set_thread_area_64(p, ARCH_SET_FS, tls);
case ARCH_SET_FS: {
stub_syscall2(__NR_arch_prctl, ARCH_SET_FS, arch->fs_base);
case ARCH_SET_FS:
syscall(SYS_arch_prctl, ARCH_SET_FS, saved_base);