Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 282 insertions, 0 deletions

diff --git a/pkg/sentry/usage/memory.go b/pkg/sentry/usage/memory.go
new file mode 100644
index 000000000..5d1b3a595
--- /dev/null
+++ b/pkg/sentry/usage/memory.go
@@ -0,0 +1,282 @@
+// Copyright 2018 Google Inc.
+//
+// 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 usage
+
+import (
+	"fmt"
+	"os"
+	"sync"
+	"sync/atomic"
+	"syscall"
+
+	"gvisor.googlesource.com/gvisor/pkg/bits"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/memutil"
+)
+
+// MemoryKind represents a type of memory used by the application.
+//
+// For efficiency reasons, it is assumed that the Memory implementation is
+// responsible for specific stats (documented below), and those may be reported
+// in aggregate independently. See the platform.Memory interface as well as the
+// control.Usage.Collect method for more information.
+type MemoryKind int
+
+const (
+	// System represents miscellaneous system memory. This may include
+	// memory that is in the process of being reclaimed, system caches,
+	// page tables, swap, etc.
+	//
+	// This memory kind is backed by platform memory.
+	System MemoryKind = iota
+
+	// Anonymous represents anonymous application memory.
+	//
+	// This memory kind is backed by platform memory.
+	Anonymous
+
+	// PageCache represents memory allocated to back sandbox-visible files that
+	// do not have a local fd. The contents of these files are buffered in
+	// memory to support application mmaps.
+	//
+	// This memory kind is backed by platform memory.
+	PageCache
+
+	// Tmpfs represents memory used by the sandbox-visible tmpfs.
+	//
+	// This memory kind is backed by platform memory.
+	Tmpfs
+
+	// Ramdiskfs represents memory used by the ramdiskfs.
+	//
+	// This memory kind is backed by platform memory.
+	Ramdiskfs
+
+	// Mapped represents memory related to files which have a local fd on the
+	// host, and thus can be directly mapped. Typically these are files backed
+	// by gofers with donated-fd support. Note that this value may not track the
+	// exact amount of memory used by mapping on the host, because we don't have
+	// any visibility into the host kernel memory management. In particular,
+	// once we map some part of a host file, the host kernel is free to
+	// abitrarily populate/decommit the pages, which it may do for various
+	// reasons (ex. host memory reclaim, NUMA balancing).
+	//
+	// This memory kind is backed by the host pagecache, via host mmaps.
+	Mapped
+)
+
+// MemoryStats tracks application memory usage in bytes. All fields correspond to the
+// memory category with the same name. This object is thread-safe if accessed
+// through the provided methods. The public fields may be safely accessed
+// directly on a copy of the object obtained from Memory.Copy().
+type MemoryStats struct {
+	System    uint64
+	Anonymous uint64
+	PageCache uint64
+	Tmpfs     uint64
+	// Lazily updated based on the value in RTMapped.
+	Mapped    uint64
+	Ramdiskfs uint64
+}
+
+// RTMemoryStats contains the memory usage values that need to be directly
+// exposed through a shared memory file for real-time access. These are
+// categories not backed by platform memory. For details about how this works,
+// see the memory accounting docs.
+//
+// N.B. Please keep the struct in sync with the API. Noteably, changes to this
+// struct requires a version bump and addition of compatibility logic in the
+// control server. As a special-case, adding fields without re-ordering existing
+// ones do not require a version bump because the mapped page we use is
+// initially zeroed. Any added field will be ignored by an older API and will be
+// zero if read by a newer API.
+type RTMemoryStats struct {
+	RTMapped uint64
+}
+
+// MemoryLocked is Memory with access methods.
+type MemoryLocked struct {
+	mu sync.RWMutex
+	// MemoryStats records the memory stats.
+	MemoryStats
+	// RTMemoryStats records the memory stats that need to be exposed through
+	// shared page.
+	*RTMemoryStats
+	// File is the backing file storing the memory stats.
+	File *os.File
+}
+
+func newMemoryLocked() MemoryLocked {
+	name := "memory-usage"
+	fd, err := memutil.CreateMemFD(name, 0)
+	if err != nil {
+		panic("error creating usage file: " + err.Error())
+	}
+	file := os.NewFile(uintptr(fd), name)
+	if err := file.Truncate(int64(RTMemoryStatsSize)); err != nil {
+		panic("error truncating usage file: " + err.Error())
+	}
+	// Note: We rely on the returned page being initially zeroed. This will
+	// always be the case for a newly mapped page from /dev/shm. If we obtain
+	// the shared memory through some other means in the future, we may have to
+	// explicitly zero the page.
+	mmap, err := syscall.Mmap(int(file.Fd()), 0, int(RTMemoryStatsSize), syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_SHARED)
+	if err != nil {
+		panic("error mapping usage file: " + err.Error())
+	}
+
+	return MemoryLocked{
+		File:          file,
+		RTMemoryStats: RTMemoryStatsPointer(mmap),
+	}
+}
+
+// MemoryAccounting is the global memory stats.
+//
+// There is no need to save or restore the global memory accounting object,
+// because individual frame kinds are saved and charged only when they become
+// resident.
+var MemoryAccounting = newMemoryLocked()
+
+func (m *MemoryLocked) incLocked(val uint64, kind MemoryKind) {
+	switch kind {
+	case System:
+		atomic.AddUint64(&m.System, val)
+	case Anonymous:
+		atomic.AddUint64(&m.Anonymous, val)
+	case PageCache:
+		atomic.AddUint64(&m.PageCache, val)
+	case Mapped:
+		atomic.AddUint64(&m.RTMapped, val)
+	case Tmpfs:
+		atomic.AddUint64(&m.Tmpfs, val)
+	case Ramdiskfs:
+		atomic.AddUint64(&m.Ramdiskfs, val)
+	default:
+		panic(fmt.Sprintf("invalid memory kind: %v", kind))
+	}
+}
+
+// Inc adds an additional usage of 'val' bytes to memory category 'kind'.
+//
+// This method is thread-safe.
+func (m *MemoryLocked) Inc(val uint64, kind MemoryKind) {
+	m.mu.RLock()
+	m.incLocked(val, kind)
+	m.mu.RUnlock()
+}
+
+func (m *MemoryLocked) decLocked(val uint64, kind MemoryKind) {
+	switch kind {
+	case System:
+		atomic.AddUint64(&m.System, ^(val - 1))
+	case Anonymous:
+		atomic.AddUint64(&m.Anonymous, ^(val - 1))
+	case PageCache:
+		atomic.AddUint64(&m.PageCache, ^(val - 1))
+	case Mapped:
+		atomic.AddUint64(&m.RTMapped, ^(val - 1))
+	case Tmpfs:
+		atomic.AddUint64(&m.Tmpfs, ^(val - 1))
+	case Ramdiskfs:
+		atomic.AddUint64(&m.Ramdiskfs, ^(val - 1))
+	default:
+		panic(fmt.Sprintf("invalid memory kind: %v", kind))
+	}
+}
+
+// Dec remove a usage of 'val' bytes from memory category 'kind'.
+//
+// This method is thread-safe.
+func (m *MemoryLocked) Dec(val uint64, kind MemoryKind) {
+	m.mu.RLock()
+	m.decLocked(val, kind)
+	m.mu.RUnlock()
+}
+
+// Move moves a usage of 'val' bytes from 'from' to 'to'.
+//
+// This method is thread-safe.
+func (m *MemoryLocked) Move(val uint64, to MemoryKind, from MemoryKind) {
+	m.mu.RLock()
+	// Just call decLocked and incLocked directly. We held the RLock to
+	// protect against concurrent callers to Total().
+	m.decLocked(val, from)
+	m.incLocked(val, to)
+	m.mu.RUnlock()
+}
+
+// totalLocked returns a total usage.
+//
+// Precondition: must be called when locked.
+func (m *MemoryLocked) totalLocked() (total uint64) {
+	total += atomic.LoadUint64(&m.System)
+	total += atomic.LoadUint64(&m.Anonymous)
+	total += atomic.LoadUint64(&m.PageCache)
+	total += atomic.LoadUint64(&m.RTMapped)
+	total += atomic.LoadUint64(&m.Tmpfs)
+	total += atomic.LoadUint64(&m.Ramdiskfs)
+	return
+}
+
+// Total returns a total memory usage.
+//
+// This method is thread-safe.
+func (m *MemoryLocked) Total() uint64 {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.totalLocked()
+}
+
+// Copy returns a copy of the structure with a total.
+//
+// This method is thread-safe.
+func (m *MemoryLocked) Copy() (MemoryStats, uint64) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	ms := m.MemoryStats
+	ms.Mapped = m.RTMapped
+	return ms, m.totalLocked()
+}
+
+// MinimumTotalMemoryBytes is the minimum reported total system memory.
+var MinimumTotalMemoryBytes uint64 = 2 << 30 // 2 GB
+
+// TotalMemory returns the "total usable memory" available.
+//
+// This number doesn't really have a true value so it's based on the following
+// inputs and further bounded to be above some minimum guaranteed value (2GB),
+// additionally ensuring that total memory reported is always less than used.
+//
+// memSize should be the platform.Memory size reported by platform.Memory.TotalSize()
+// used is the total memory reported by MemoryLocked.Total()
+func TotalMemory(memSize, used uint64) uint64 {
+	if memSize < MinimumTotalMemoryBytes {
+		memSize = MinimumTotalMemoryBytes
+	}
+	if memSize < used {
+		memSize = used
+		// Bump totalSize to the next largest power of 2, if one exists, so
+		// that MemFree isn't 0.
+		if msb := bits.MostSignificantOne64(memSize); msb < 63 {
+			memSize = uint64(1) << (uint(msb) + 1)
+		}
+	}
+	return memSize
+}
+
+// IncrementalMappedAccounting controls whether host mapped memory is accounted
+// incrementally during map translation. This may be modified during early
+// initialization, and is read-only afterward.
+var IncrementalMappedAccounting = false