Merge 216da0b7 (automated)

4 files changed, 794 insertions, 0 deletions

diff --git a/pkg/sentry/kernel/epoll/epoll.go b/pkg/sentry/kernel/epoll/epoll.go
new file mode 100644
index 000000000..bbacba1f4
--- /dev/null
+++ b/pkg/sentry/kernel/epoll/epoll.go
@@ -0,0 +1,473 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package epoll provides an implementation of Linux's IO event notification
+// facility. See epoll(7) for more details.
+package epoll
+
+import (
+	"fmt"
+	"sync"
+	"syscall"
+
+	"gvisor.googlesource.com/gvisor/pkg/refs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/anon"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/kdefs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
+)
+
+// Event describes the event mask that was observed and the user data to be
+// returned when one of the events occurs. It has this format to match the linux
+// format to avoid extra copying/allocation when writing events to userspace.
+type Event struct {
+	// Events is the event mask containing the set of events that have been
+	// observed on an entry.
+	Events uint32
+
+	// Data is an opaque 64-bit value provided by the caller when adding the
+	// entry, and returned to the caller when the entry reports an event.
+	Data [2]int32
+}
+
+// EntryFlags is a bitmask that holds an entry's flags.
+type EntryFlags int
+
+// Valid entry flags.
+const (
+	OneShot EntryFlags = 1 << iota
+	EdgeTriggered
+)
+
+// FileIdentifier identifies a file. We cannot use just the FD because it could
+// potentially be reassigned. We also cannot use just the file pointer because
+// it is possible to have multiple entries for the same file object as long as
+// they are created with different FDs (i.e., the FDs point to the same file).
+//
+// +stateify savable
+type FileIdentifier struct {
+	File *fs.File `state:"wait"`
+	Fd   kdefs.FD
+}
+
+// pollEntry holds all the state associated with an event poll entry, that is,
+// a file being observed by an event poll object.
+//
+// +stateify savable
+type pollEntry struct {
+	pollEntryEntry
+	file     *refs.WeakRef  `state:"manual"`
+	id       FileIdentifier `state:"wait"`
+	userData [2]int32
+	waiter   waiter.Entry `state:"manual"`
+	mask     waiter.EventMask
+	flags    EntryFlags
+
+	epoll *EventPoll
+
+	// We cannot save the current list pointer as it points into EventPoll
+	// struct, while state framework currently does not support such
+	// in-struct pointers. Instead, EventPoll will properly set this field
+	// in its loading logic.
+	curList *pollEntryList `state:"nosave"`
+}
+
+// WeakRefGone implements refs.WeakRefUser.WeakRefGone.
+// weakReferenceGone is called when the file in the weak reference is destroyed.
+// The poll entry is removed in response to this.
+func (p *pollEntry) WeakRefGone() {
+	p.epoll.RemoveEntry(p.id)
+}
+
+// EventPoll holds all the state associated with an event poll object, that is,
+// collection of files to observe and their current state.
+//
+// +stateify savable
+type EventPoll struct {
+	fsutil.FilePipeSeek             `state:"zerovalue"`
+	fsutil.FileNotDirReaddir        `state:"zerovalue"`
+	fsutil.FileNoFsync              `state:"zerovalue"`
+	fsutil.FileNoopFlush            `state:"zerovalue"`
+	fsutil.FileNoIoctl              `state:"zerovalue"`
+	fsutil.FileNoMMap               `state:"zerovalue"`
+	fsutil.FileNoSplice             `state:"nosave"`
+	fsutil.FileUseInodeUnstableAttr `state:"nosave"`
+
+	// Wait queue is used to notify interested parties when the event poll
+	// object itself becomes readable or writable.
+	waiter.Queue `state:"zerovalue"`
+
+	// files is the map of all the files currently being observed, it is
+	// protected by mu.
+	mu    sync.Mutex `state:"nosave"`
+	files map[FileIdentifier]*pollEntry
+
+	// listsMu protects manipulation of the lists below. It needs to be a
+	// different lock to avoid circular lock acquisition order involving
+	// the wait queue mutexes and mu. The full order is mu, observed file
+	// wait queue mutex, then listsMu; this allows listsMu to be acquired
+	// when readyCallback is called.
+	//
+	// An entry is always in one of the following lists:
+	//	readyList -- when there's a chance that it's ready to have
+	//		events delivered to epoll waiters. Given that being
+	//		ready is a transient state, the Readiness() and
+	//		readEvents() functions always call the entry's file
+	//		Readiness() function to confirm it's ready.
+	//	waitingList -- when there's no chance that the entry is ready,
+	//		so it's waiting for the readyCallback to be called
+	//		on it before it gets moved to the readyList.
+	//	disabledList -- when the entry is disabled. This happens when
+	//		a one-shot entry gets delivered via readEvents().
+	listsMu      sync.Mutex `state:"nosave"`
+	readyList    pollEntryList
+	waitingList  pollEntryList
+	disabledList pollEntryList
+}
+
+// cycleMu is used to serialize all the cycle checks. This is only used when
+// an event poll file is added as an entry to another event poll. Such checks
+// are serialized to avoid lock acquisition order inversion: if a thread is
+// adding A to B, and another thread is adding B to A, each would acquire A's
+// and B's mutexes in reverse order, and could cause deadlocks. Having this
+// lock prevents this by allowing only one check at a time to happen.
+//
+// We do the cycle check to prevent callers from introducing potentially
+// infinite recursions. If a caller were to add A to B and then B to A, for
+// event poll A to know if it's readable, it would need to check event poll B,
+// which in turn would need event poll A and so on indefinitely.
+var cycleMu sync.Mutex
+
+// NewEventPoll allocates and initializes a new event poll object.
+func NewEventPoll(ctx context.Context) *fs.File {
+	// name matches fs/eventpoll.c:epoll_create1.
+	dirent := fs.NewDirent(anon.NewInode(ctx), fmt.Sprintf("anon_inode:[eventpoll]"))
+	return fs.NewFile(ctx, dirent, fs.FileFlags{}, &EventPoll{
+		files: make(map[FileIdentifier]*pollEntry),
+	})
+}
+
+// Release implements fs.FileOperations.Release.
+func (e *EventPoll) Release() {
+	// We need to take the lock now because files may be attempting to
+	// remove entries in parallel if they get destroyed.
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	// Go through all entries and clean up.
+	for _, entry := range e.files {
+		entry.id.File.EventUnregister(&entry.waiter)
+		entry.file.Drop()
+	}
+}
+
+// Read implements fs.FileOperations.Read.
+func (*EventPoll) Read(context.Context, *fs.File, usermem.IOSequence, int64) (int64, error) {
+	return 0, syscall.ENOSYS
+}
+
+// Write implements fs.FileOperations.Write.
+func (*EventPoll) Write(context.Context, *fs.File, usermem.IOSequence, int64) (int64, error) {
+	return 0, syscall.ENOSYS
+}
+
+// eventsAvailable determines if 'e' has events available for delivery.
+func (e *EventPoll) eventsAvailable() bool {
+	e.listsMu.Lock()
+
+	for it := e.readyList.Front(); it != nil; {
+		entry := it
+		it = it.Next()
+
+		// If the entry is ready, we know 'e' has at least one entry
+		// ready for delivery.
+		ready := entry.id.File.Readiness(entry.mask)
+		if ready != 0 {
+			e.listsMu.Unlock()
+			return true
+		}
+
+		// Entry is not ready, so move it to waiting list.
+		e.readyList.Remove(entry)
+		e.waitingList.PushBack(entry)
+		entry.curList = &e.waitingList
+	}
+
+	e.listsMu.Unlock()
+
+	return false
+}
+
+// Readiness determines if the event poll object is currently readable (i.e.,
+// if there are pending events for delivery).
+func (e *EventPoll) Readiness(mask waiter.EventMask) waiter.EventMask {
+	ready := waiter.EventMask(0)
+
+	if (mask&waiter.EventIn) != 0 && e.eventsAvailable() {
+		ready |= waiter.EventIn
+	}
+
+	return ready
+}
+
+// ReadEvents returns up to max available events.
+func (e *EventPoll) ReadEvents(max int) []Event {
+	var local pollEntryList
+	var ret []Event
+
+	e.listsMu.Lock()
+
+	// Go through all entries we believe may be ready.
+	for it := e.readyList.Front(); it != nil && len(ret) < max; {
+		entry := it
+		it = it.Next()
+
+		// Check the entry's readiness. It it's not really ready, we
+		// just put it back in the waiting list and move on to the next
+		// entry.
+		ready := entry.id.File.Readiness(entry.mask) & entry.mask
+		if ready == 0 {
+			e.readyList.Remove(entry)
+			e.waitingList.PushBack(entry)
+			entry.curList = &e.waitingList
+
+			continue
+		}
+
+		// Add event to the array that will be returned to caller.
+		ret = append(ret, Event{
+			Events: uint32(ready),
+			Data:   entry.userData,
+		})
+
+		// The entry is consumed, so we must move it to the disabled
+		// list in case it's one-shot, or back to the wait list if it's
+		// edge-triggered. If it's neither, we leave it in the ready
+		// list so that its readiness can be checked the next time
+		// around; however, we must move it to the end of the list so
+		// that other events can be delivered as well.
+		e.readyList.Remove(entry)
+		if entry.flags&OneShot != 0 {
+			e.disabledList.PushBack(entry)
+			entry.curList = &e.disabledList
+		} else if entry.flags&EdgeTriggered != 0 {
+			e.waitingList.PushBack(entry)
+			entry.curList = &e.waitingList
+		} else {
+			local.PushBack(entry)
+		}
+	}
+
+	e.readyList.PushBackList(&local)
+
+	e.listsMu.Unlock()
+
+	return ret
+}
+
+// readyCallback is called when one of the files we're polling becomes ready. It
+// moves said file to the readyList if it's currently in the waiting list.
+type readyCallback struct{}
+
+// Callback implements waiter.EntryCallback.Callback.
+func (*readyCallback) Callback(w *waiter.Entry) {
+	entry := w.Context.(*pollEntry)
+	e := entry.epoll
+
+	e.listsMu.Lock()
+
+	if entry.curList == &e.waitingList {
+		e.waitingList.Remove(entry)
+		e.readyList.PushBack(entry)
+		entry.curList = &e.readyList
+
+		e.Notify(waiter.EventIn)
+	}
+
+	e.listsMu.Unlock()
+}
+
+// initEntryReadiness initializes the entry's state with regards to its
+// readiness by placing it in the appropriate list and registering for
+// notifications.
+func (e *EventPoll) initEntryReadiness(entry *pollEntry) {
+	// A new entry starts off in the waiting list.
+	e.listsMu.Lock()
+	e.waitingList.PushBack(entry)
+	entry.curList = &e.waitingList
+	e.listsMu.Unlock()
+
+	// Register for event notifications.
+	f := entry.id.File
+	f.EventRegister(&entry.waiter, entry.mask)
+
+	// Check if the file happens to already be in a ready state.
+	ready := f.Readiness(entry.mask) & entry.mask
+	if ready != 0 {
+		(*readyCallback).Callback(nil, &entry.waiter)
+	}
+}
+
+// observes checks if event poll object e is directly or indirectly observing
+// event poll object ep. It uses a bounded recursive depth-first search.
+func (e *EventPoll) observes(ep *EventPoll, depthLeft int) bool {
+	// If we reached the maximum depth, we'll consider that we found it
+	// because we don't want to allow chains that are too long.
+	if depthLeft <= 0 {
+		return true
+	}
+
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	// Go through each observed file and check if it is or observes ep.
+	for id := range e.files {
+		f, ok := id.File.FileOperations.(*EventPoll)
+		if !ok {
+			continue
+		}
+
+		if f == ep || f.observes(ep, depthLeft-1) {
+			return true
+		}
+	}
+
+	return false
+}
+
+// AddEntry adds a new file to the collection of files observed by e.
+func (e *EventPoll) AddEntry(id FileIdentifier, flags EntryFlags, mask waiter.EventMask, data [2]int32) error {
+	// Acquire cycle check lock if another event poll is being added.
+	ep, ok := id.File.FileOperations.(*EventPoll)
+	if ok {
+		cycleMu.Lock()
+		defer cycleMu.Unlock()
+	}
+
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	// Fail if the file already has an entry.
+	if _, ok := e.files[id]; ok {
+		return syscall.EEXIST
+	}
+
+	// Check if a cycle would be created. We use 4 as the limit because
+	// that's the value used by linux and we want to emulate it.
+	if ep != nil {
+		if e == ep {
+			return syscall.EINVAL
+		}
+
+		if ep.observes(e, 4) {
+			return syscall.ELOOP
+		}
+	}
+
+	// Create new entry and add it to map.
+	//
+	// N.B. Even though we are creating a weak reference here, we know it
+	//      won't trigger a callback because we hold a reference to the file
+	//      throughout the execution of this function.
+	entry := &pollEntry{
+		id:       id,
+		userData: data,
+		epoll:    e,
+		flags:    flags,
+		waiter:   waiter.Entry{Callback: &readyCallback{}},
+		mask:     mask,
+	}
+	entry.waiter.Context = entry
+	e.files[id] = entry
+	entry.file = refs.NewWeakRef(id.File, entry)
+
+	// Initialize the readiness state of the new entry.
+	e.initEntryReadiness(entry)
+
+	return nil
+}
+
+// UpdateEntry updates the flags, mask and user data associated with a file that
+// is already part of the collection of observed files.
+func (e *EventPoll) UpdateEntry(id FileIdentifier, flags EntryFlags, mask waiter.EventMask, data [2]int32) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	// Fail if the file doesn't have an entry.
+	entry, ok := e.files[id]
+	if !ok {
+		return syscall.ENOENT
+	}
+
+	// Unregister the old mask and remove entry from the list it's in, so
+	// readyCallback is guaranteed to not be called on this entry anymore.
+	entry.id.File.EventUnregister(&entry.waiter)
+
+	// Remove entry from whatever list it's in. This ensure that no other
+	// threads have access to this entry as the only way left to find it
+	// is via e.files, but we hold e.mu, which prevents that.
+	e.listsMu.Lock()
+	entry.curList.Remove(entry)
+	e.listsMu.Unlock()
+
+	// Initialize new readiness state.
+	entry.flags = flags
+	entry.mask = mask
+	entry.userData = data
+	e.initEntryReadiness(entry)
+
+	return nil
+}
+
+// RemoveEntry a files from the collection of observed files.
+func (e *EventPoll) RemoveEntry(id FileIdentifier) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	// Fail if the file doesn't have an entry.
+	entry, ok := e.files[id]
+	if !ok {
+		return syscall.ENOENT
+	}
+
+	// Unregister from file first so that no concurrent attempts will be
+	// made to manipulate the file.
+	entry.id.File.EventUnregister(&entry.waiter)
+
+	// Remove from the current list.
+	e.listsMu.Lock()
+	entry.curList.Remove(entry)
+	entry.curList = nil
+	e.listsMu.Unlock()
+
+	// Remove file from map, and drop weak reference.
+	delete(e.files, id)
+	entry.file.Drop()
+
+	return nil
+}
+
+// UnregisterEpollWaiters removes the epoll waiter objects from the waiting
+// queues. This is different from Release() as the file is not dereferenced.
+func (e *EventPoll) UnregisterEpollWaiters() {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	for _, entry := range e.files {
+		entry.id.File.EventUnregister(&entry.waiter)
+	}
+}
diff --git a/pkg/sentry/kernel/epoll/epoll_list.go b/pkg/sentry/kernel/epoll/epoll_list.go
new file mode 100755
index 000000000..94d5c9e57
--- /dev/null
+++ b/pkg/sentry/kernel/epoll/epoll_list.go
@@ -0,0 +1,173 @@
+package epoll
+
+// ElementMapper provides an identity mapping by default.
+//
+// This can be replaced to provide a struct that maps elements to linker
+// objects, if they are not the same. An ElementMapper is not typically
+// required if: Linker is left as is, Element is left as is, or Linker and
+// Element are the same type.
+type pollEntryElementMapper struct{}
+
+// linkerFor maps an Element to a Linker.
+//
+// This default implementation should be inlined.
+//
+//go:nosplit
+func (pollEntryElementMapper) linkerFor(elem *pollEntry) *pollEntry { return elem }
+
+// List is an intrusive list. Entries can be added to or removed from the list
+// in O(1) time and with no additional memory allocations.
+//
+// The zero value for List is an empty list ready to use.
+//
+// To iterate over a list (where l is a List):
+//      for e := l.Front(); e != nil; e = e.Next() {
+// 		// do something with e.
+//      }
+//
+// +stateify savable
+type pollEntryList struct {
+	head *pollEntry
+	tail *pollEntry
+}
+
+// Reset resets list l to the empty state.
+func (l *pollEntryList) Reset() {
+	l.head = nil
+	l.tail = nil
+}
+
+// Empty returns true iff the list is empty.
+func (l *pollEntryList) Empty() bool {
+	return l.head == nil
+}
+
+// Front returns the first element of list l or nil.
+func (l *pollEntryList) Front() *pollEntry {
+	return l.head
+}
+
+// Back returns the last element of list l or nil.
+func (l *pollEntryList) Back() *pollEntry {
+	return l.tail
+}
+
+// PushFront inserts the element e at the front of list l.
+func (l *pollEntryList) PushFront(e *pollEntry) {
+	pollEntryElementMapper{}.linkerFor(e).SetNext(l.head)
+	pollEntryElementMapper{}.linkerFor(e).SetPrev(nil)
+
+	if l.head != nil {
+		pollEntryElementMapper{}.linkerFor(l.head).SetPrev(e)
+	} else {
+		l.tail = e
+	}
+
+	l.head = e
+}
+
+// PushBack inserts the element e at the back of list l.
+func (l *pollEntryList) PushBack(e *pollEntry) {
+	pollEntryElementMapper{}.linkerFor(e).SetNext(nil)
+	pollEntryElementMapper{}.linkerFor(e).SetPrev(l.tail)
+
+	if l.tail != nil {
+		pollEntryElementMapper{}.linkerFor(l.tail).SetNext(e)
+	} else {
+		l.head = e
+	}
+
+	l.tail = e
+}
+
+// PushBackList inserts list m at the end of list l, emptying m.
+func (l *pollEntryList) PushBackList(m *pollEntryList) {
+	if l.head == nil {
+		l.head = m.head
+		l.tail = m.tail
+	} else if m.head != nil {
+		pollEntryElementMapper{}.linkerFor(l.tail).SetNext(m.head)
+		pollEntryElementMapper{}.linkerFor(m.head).SetPrev(l.tail)
+
+		l.tail = m.tail
+	}
+
+	m.head = nil
+	m.tail = nil
+}
+
+// InsertAfter inserts e after b.
+func (l *pollEntryList) InsertAfter(b, e *pollEntry) {
+	a := pollEntryElementMapper{}.linkerFor(b).Next()
+	pollEntryElementMapper{}.linkerFor(e).SetNext(a)
+	pollEntryElementMapper{}.linkerFor(e).SetPrev(b)
+	pollEntryElementMapper{}.linkerFor(b).SetNext(e)
+
+	if a != nil {
+		pollEntryElementMapper{}.linkerFor(a).SetPrev(e)
+	} else {
+		l.tail = e
+	}
+}
+
+// InsertBefore inserts e before a.
+func (l *pollEntryList) InsertBefore(a, e *pollEntry) {
+	b := pollEntryElementMapper{}.linkerFor(a).Prev()
+	pollEntryElementMapper{}.linkerFor(e).SetNext(a)
+	pollEntryElementMapper{}.linkerFor(e).SetPrev(b)
+	pollEntryElementMapper{}.linkerFor(a).SetPrev(e)
+
+	if b != nil {
+		pollEntryElementMapper{}.linkerFor(b).SetNext(e)
+	} else {
+		l.head = e
+	}
+}
+
+// Remove removes e from l.
+func (l *pollEntryList) Remove(e *pollEntry) {
+	prev := pollEntryElementMapper{}.linkerFor(e).Prev()
+	next := pollEntryElementMapper{}.linkerFor(e).Next()
+
+	if prev != nil {
+		pollEntryElementMapper{}.linkerFor(prev).SetNext(next)
+	} else {
+		l.head = next
+	}
+
+	if next != nil {
+		pollEntryElementMapper{}.linkerFor(next).SetPrev(prev)
+	} else {
+		l.tail = prev
+	}
+}
+
+// Entry is a default implementation of Linker. Users can add anonymous fields
+// of this type to their structs to make them automatically implement the
+// methods needed by List.
+//
+// +stateify savable
+type pollEntryEntry struct {
+	next *pollEntry
+	prev *pollEntry
+}
+
+// Next returns the entry that follows e in the list.
+func (e *pollEntryEntry) Next() *pollEntry {
+	return e.next
+}
+
+// Prev returns the entry that precedes e in the list.
+func (e *pollEntryEntry) Prev() *pollEntry {
+	return e.prev
+}
+
+// SetNext assigns 'entry' as the entry that follows e in the list.
+func (e *pollEntryEntry) SetNext(elem *pollEntry) {
+	e.next = elem
+}
+
+// SetPrev assigns 'entry' as the entry that precedes e in the list.
+func (e *pollEntryEntry) SetPrev(elem *pollEntry) {
+	e.prev = elem
+}
diff --git a/pkg/sentry/kernel/epoll/epoll_state.go b/pkg/sentry/kernel/epoll/epoll_state.go
new file mode 100644
index 000000000..4c3c38f9e
--- /dev/null
+++ b/pkg/sentry/kernel/epoll/epoll_state.go
@@ -0,0 +1,49 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package epoll
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/refs"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
+)
+
+// afterLoad is invoked by stateify.
+func (p *pollEntry) afterLoad() {
+	p.waiter = waiter.Entry{Callback: &readyCallback{}}
+	p.waiter.Context = p
+	p.file = refs.NewWeakRef(p.id.File, p)
+	p.id.File.EventRegister(&p.waiter, p.mask)
+}
+
+// afterLoad is invoked by stateify.
+func (e *EventPoll) afterLoad() {
+	e.listsMu.Lock()
+	defer e.listsMu.Unlock()
+
+	for _, ls := range []*pollEntryList{&e.waitingList, &e.readyList, &e.disabledList} {
+		for it := ls.Front(); it != nil; it = it.Next() {
+			it.curList = ls
+		}
+	}
+
+	for it := e.waitingList.Front(); it != nil; it = it.Next() {
+		if it.id.File.Readiness(it.mask) != 0 {
+			e.waitingList.Remove(it)
+			e.readyList.PushBack(it)
+			it.curList = &e.readyList
+			e.Notify(waiter.EventIn)
+		}
+	}
+}
diff --git a/pkg/sentry/kernel/epoll/epoll_state_autogen.go b/pkg/sentry/kernel/epoll/epoll_state_autogen.go
new file mode 100755
index 000000000..a361ff37b
--- /dev/null
+++ b/pkg/sentry/kernel/epoll/epoll_state_autogen.go
@@ -0,0 +1,99 @@
+// automatically generated by stateify.
+
+package epoll
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/state"
+)
+
+func (x *FileIdentifier) beforeSave() {}
+func (x *FileIdentifier) save(m state.Map) {
+	x.beforeSave()
+	m.Save("File", &x.File)
+	m.Save("Fd", &x.Fd)
+}
+
+func (x *FileIdentifier) afterLoad() {}
+func (x *FileIdentifier) load(m state.Map) {
+	m.LoadWait("File", &x.File)
+	m.Load("Fd", &x.Fd)
+}
+
+func (x *pollEntry) beforeSave() {}
+func (x *pollEntry) save(m state.Map) {
+	x.beforeSave()
+	m.Save("pollEntryEntry", &x.pollEntryEntry)
+	m.Save("id", &x.id)
+	m.Save("userData", &x.userData)
+	m.Save("mask", &x.mask)
+	m.Save("flags", &x.flags)
+	m.Save("epoll", &x.epoll)
+}
+
+func (x *pollEntry) load(m state.Map) {
+	m.Load("pollEntryEntry", &x.pollEntryEntry)
+	m.LoadWait("id", &x.id)
+	m.Load("userData", &x.userData)
+	m.Load("mask", &x.mask)
+	m.Load("flags", &x.flags)
+	m.Load("epoll", &x.epoll)
+	m.AfterLoad(x.afterLoad)
+}
+
+func (x *EventPoll) beforeSave() {}
+func (x *EventPoll) save(m state.Map) {
+	x.beforeSave()
+	if !state.IsZeroValue(x.FilePipeSeek) { m.Failf("FilePipeSeek is %v, expected zero", x.FilePipeSeek) }
+	if !state.IsZeroValue(x.FileNotDirReaddir) { m.Failf("FileNotDirReaddir is %v, expected zero", x.FileNotDirReaddir) }
+	if !state.IsZeroValue(x.FileNoFsync) { m.Failf("FileNoFsync is %v, expected zero", x.FileNoFsync) }
+	if !state.IsZeroValue(x.FileNoopFlush) { m.Failf("FileNoopFlush is %v, expected zero", x.FileNoopFlush) }
+	if !state.IsZeroValue(x.FileNoIoctl) { m.Failf("FileNoIoctl is %v, expected zero", x.FileNoIoctl) }
+	if !state.IsZeroValue(x.FileNoMMap) { m.Failf("FileNoMMap is %v, expected zero", x.FileNoMMap) }
+	if !state.IsZeroValue(x.Queue) { m.Failf("Queue is %v, expected zero", x.Queue) }
+	m.Save("files", &x.files)
+	m.Save("readyList", &x.readyList)
+	m.Save("waitingList", &x.waitingList)
+	m.Save("disabledList", &x.disabledList)
+}
+
+func (x *EventPoll) load(m state.Map) {
+	m.Load("files", &x.files)
+	m.Load("readyList", &x.readyList)
+	m.Load("waitingList", &x.waitingList)
+	m.Load("disabledList", &x.disabledList)
+	m.AfterLoad(x.afterLoad)
+}
+
+func (x *pollEntryList) beforeSave() {}
+func (x *pollEntryList) save(m state.Map) {
+	x.beforeSave()
+	m.Save("head", &x.head)
+	m.Save("tail", &x.tail)
+}
+
+func (x *pollEntryList) afterLoad() {}
+func (x *pollEntryList) load(m state.Map) {
+	m.Load("head", &x.head)
+	m.Load("tail", &x.tail)
+}
+
+func (x *pollEntryEntry) beforeSave() {}
+func (x *pollEntryEntry) save(m state.Map) {
+	x.beforeSave()
+	m.Save("next", &x.next)
+	m.Save("prev", &x.prev)
+}
+
+func (x *pollEntryEntry) afterLoad() {}
+func (x *pollEntryEntry) load(m state.Map) {
+	m.Load("next", &x.next)
+	m.Load("prev", &x.prev)
+}
+
+func init() {
+	state.Register("epoll.FileIdentifier", (*FileIdentifier)(nil), state.Fns{Save: (*FileIdentifier).save, Load: (*FileIdentifier).load})
+	state.Register("epoll.pollEntry", (*pollEntry)(nil), state.Fns{Save: (*pollEntry).save, Load: (*pollEntry).load})
+	state.Register("epoll.EventPoll", (*EventPoll)(nil), state.Fns{Save: (*EventPoll).save, Load: (*EventPoll).load})
+	state.Register("epoll.pollEntryList", (*pollEntryList)(nil), state.Fns{Save: (*pollEntryList).save, Load: (*pollEntryList).load})
+	state.Register("epoll.pollEntryEntry", (*pollEntryEntry)(nil), state.Fns{Save: (*pollEntryEntry).save, Load: (*pollEntryEntry).load})
+}