stub_syscall2
stub_syscall2(__NR_close, fd_map[--num_fds], 0);
res = stub_syscall2(__NR_munmap,
stub_syscall2(__NR_kill, stub_syscall0(__NR_getpid), SIGSTOP);
stub_syscall2(__NR_prctl, PR_SET_NAME, (unsigned long)"uml-userspace");
stub_syscall2(__NR_prctl, PR_SET_PDEATHSIG, SIGKILL);
stub_syscall2(__NR_sigaltstack, (unsigned long)&stack, 0);
stub_syscall2(__NR_arch_prctl, ARCH_SET_FS, arch->fs_base);
stub_syscall2(__NR_arch_prctl, ARCH_SET_GS, arch->gs_base);