diff --git a/vendor/golang.org/x/sys/unix/epoll_zos.go b/vendor/golang.org/x/sys/unix/epoll_zos.go
new file mode 100644
index 0000000..cedaf7e
--- /dev/null
+++ b/vendor/golang.org/x/sys/unix/epoll_zos.go
@@ -0,0 +1,221 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build zos && s390x
+// +build zos,s390x
+
+package unix
+
+import (
+	"sync"
+)
+
+// This file simulates epoll on z/OS using poll.
+
+// Analogous to epoll_event on Linux.
+// TODO(neeilan): Pad is because the Linux kernel expects a 96-bit struct. We never pass this to the kernel; remove?
+type EpollEvent struct {
+	Events uint32
+	Fd     int32
+	Pad    int32
+}
+
+const (
+	EPOLLERR      = 0x8
+	EPOLLHUP      = 0x10
+	EPOLLIN       = 0x1
+	EPOLLMSG      = 0x400
+	EPOLLOUT      = 0x4
+	EPOLLPRI      = 0x2
+	EPOLLRDBAND   = 0x80
+	EPOLLRDNORM   = 0x40
+	EPOLLWRBAND   = 0x200
+	EPOLLWRNORM   = 0x100
+	EPOLL_CTL_ADD = 0x1
+	EPOLL_CTL_DEL = 0x2
+	EPOLL_CTL_MOD = 0x3
+	// The following constants are part of the epoll API, but represent
+	// currently unsupported functionality on z/OS.
+	// EPOLL_CLOEXEC  = 0x80000
+	// EPOLLET        = 0x80000000
+	// EPOLLONESHOT   = 0x40000000
+	// EPOLLRDHUP     = 0x2000     // Typically used with edge-triggered notis
+	// EPOLLEXCLUSIVE = 0x10000000 // Exclusive wake-up mode
+	// EPOLLWAKEUP    = 0x20000000 // Relies on Linux's BLOCK_SUSPEND capability
+)
+
+// TODO(neeilan): We can eliminate these epToPoll / pToEpoll calls by using identical mask values for POLL/EPOLL
+// constants where possible The lower 16 bits of epoll events (uint32) can fit any system poll event (int16).
+
+// epToPollEvt converts epoll event field to poll equivalent.
+// In epoll, Events is a 32-bit field, while poll uses 16 bits.
+func epToPollEvt(events uint32) int16 {
+	var ep2p = map[uint32]int16{
+		EPOLLIN:  POLLIN,
+		EPOLLOUT: POLLOUT,
+		EPOLLHUP: POLLHUP,
+		EPOLLPRI: POLLPRI,
+		EPOLLERR: POLLERR,
+	}
+
+	var pollEvts int16 = 0
+	for epEvt, pEvt := range ep2p {
+		if (events & epEvt) != 0 {
+			pollEvts |= pEvt
+		}
+	}
+
+	return pollEvts
+}
+
+// pToEpollEvt converts 16 bit poll event bitfields to 32-bit epoll event fields.
+func pToEpollEvt(revents int16) uint32 {
+	var p2ep = map[int16]uint32{
+		POLLIN:  EPOLLIN,
+		POLLOUT: EPOLLOUT,
+		POLLHUP: EPOLLHUP,
+		POLLPRI: EPOLLPRI,
+		POLLERR: EPOLLERR,
+	}
+
+	var epollEvts uint32 = 0
+	for pEvt, epEvt := range p2ep {
+		if (revents & pEvt) != 0 {
+			epollEvts |= epEvt
+		}
+	}
+
+	return epollEvts
+}
+
+// Per-process epoll implementation.
+type epollImpl struct {
+	mu       sync.Mutex
+	epfd2ep  map[int]*eventPoll
+	nextEpfd int
+}
+
+// eventPoll holds a set of file descriptors being watched by the process. A process can have multiple epoll instances.
+// On Linux, this is an in-kernel data structure accessed through a fd.
+type eventPoll struct {
+	mu  sync.Mutex
+	fds map[int]*EpollEvent
+}
+
+// epoll impl for this process.
+var impl epollImpl = epollImpl{
+	epfd2ep:  make(map[int]*eventPoll),
+	nextEpfd: 0,
+}
+
+func (e *epollImpl) epollcreate(size int) (epfd int, err error) {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	epfd = e.nextEpfd
+	e.nextEpfd++
+
+	e.epfd2ep[epfd] = &eventPoll{
+		fds: make(map[int]*EpollEvent),
+	}
+	return epfd, nil
+}
+
+func (e *epollImpl) epollcreate1(flag int) (fd int, err error) {
+	return e.epollcreate(4)
+}
+
+func (e *epollImpl) epollctl(epfd int, op int, fd int, event *EpollEvent) (err error) {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	ep, ok := e.epfd2ep[epfd]
+	if !ok {
+
+		return EBADF
+	}
+
+	switch op {
+	case EPOLL_CTL_ADD:
+		// TODO(neeilan): When we make epfds and fds disjoint, detect epoll
+		// loops here (instances watching each other) and return ELOOP.
+		if _, ok := ep.fds[fd]; ok {
+			return EEXIST
+		}
+		ep.fds[fd] = event
+	case EPOLL_CTL_MOD:
+		if _, ok := ep.fds[fd]; !ok {
+			return ENOENT
+		}
+		ep.fds[fd] = event
+	case EPOLL_CTL_DEL:
+		if _, ok := ep.fds[fd]; !ok {
+			return ENOENT
+		}
+		delete(ep.fds, fd)
+
+	}
+	return nil
+}
+
+// Must be called while holding ep.mu
+func (ep *eventPoll) getFds() []int {
+	fds := make([]int, len(ep.fds))
+	for fd := range ep.fds {
+		fds = append(fds, fd)
+	}
+	return fds
+}
+
+func (e *epollImpl) epollwait(epfd int, events []EpollEvent, msec int) (n int, err error) {
+	e.mu.Lock() // in [rare] case of concurrent epollcreate + epollwait
+	ep, ok := e.epfd2ep[epfd]
+
+	if !ok {
+		e.mu.Unlock()
+		return 0, EBADF
+	}
+
+	pollfds := make([]PollFd, 4)
+	for fd, epollevt := range ep.fds {
+		pollfds = append(pollfds, PollFd{Fd: int32(fd), Events: epToPollEvt(epollevt.Events)})
+	}
+	e.mu.Unlock()
+
+	n, err = Poll(pollfds, msec)
+	if err != nil {
+		return n, err
+	}
+
+	i := 0
+	for _, pFd := range pollfds {
+		if pFd.Revents != 0 {
+			events[i] = EpollEvent{Fd: pFd.Fd, Events: pToEpollEvt(pFd.Revents)}
+			i++
+		}
+
+		if i == n {
+			break
+		}
+	}
+
+	return n, nil
+}
+
+func EpollCreate(size int) (fd int, err error) {
+	return impl.epollcreate(size)
+}
+
+func EpollCreate1(flag int) (fd int, err error) {
+	return impl.epollcreate1(flag)
+}
+
+func EpollCtl(epfd int, op int, fd int, event *EpollEvent) (err error) {
+	return impl.epollctl(epfd, op, fd, event)
+}
+
+// Because EpollWait mutates events, the caller is expected to coordinate
+// concurrent access if calling with the same epfd from multiple goroutines.
+func EpollWait(epfd int, events []EpollEvent, msec int) (n int, err error) {
+	return impl.epollwait(epfd, events, msec)
+}