runtime/pprof: write profiles in protobuf format.

Added functions with suffix proto and stuff from pprof tool to translate
to protobuf. Done as the profile proto is more extensible than the legacy
pprof format and is pprof's preferred profile format. Large part was taken
from https://github.com/google/pprof tool. Tested by hand and compared the
result with translated by pprof tool, profiles are identical.
Fixes #16093
Change-Id: I5acdb2809cab0d16ed4694fdaa7b8ddfd68df11e
Reviewed-on: https://go-review.googlesource.com/30556
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>

5 files changed, 1052 insertions, 0 deletions

diff --git a/src/runtime/pprof/internal/profile/encode.go b/src/runtime/pprof/internal/profile/encode.go
new file mode 100644
index 0000000000..bf8893136a
--- /dev/null
+++ b/src/runtime/pprof/internal/profile/encode.go
@@ -0,0 +1,187 @@
+// Copyright 2016 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.
+
+package profile
+
+import (
+	"sort"
+)
+
+// preEncode populates the unexported fields to be used by encode
+// (with suffix X) from the corresponding exported fields. The
+// exported fields are cleared up to facilitate testing.
+func (p *Profile) preEncode() {
+	strings := make(map[string]int)
+	addString(strings, "")
+
+	for _, st := range p.SampleType {
+		st.typeX = addString(strings, st.Type)
+		st.unitX = addString(strings, st.Unit)
+	}
+
+	for _, s := range p.Sample {
+		s.labelX = nil
+		var keys []string
+		for k := range s.Label {
+			keys = append(keys, k)
+		}
+		sort.Strings(keys)
+		for _, k := range keys {
+			vs := s.Label[k]
+			for _, v := range vs {
+				s.labelX = append(s.labelX,
+					Label{
+						keyX: addString(strings, k),
+						strX: addString(strings, v),
+					},
+				)
+			}
+		}
+		var numKeys []string
+		for k := range s.NumLabel {
+			numKeys = append(numKeys, k)
+		}
+		sort.Strings(numKeys)
+		for _, k := range numKeys {
+			vs := s.NumLabel[k]
+			for _, v := range vs {
+				s.labelX = append(s.labelX,
+					Label{
+						keyX: addString(strings, k),
+						numX: v,
+					},
+				)
+			}
+		}
+		s.locationIDX = nil
+		for _, l := range s.Location {
+			s.locationIDX = append(s.locationIDX, l.ID)
+		}
+	}
+
+	for _, m := range p.Mapping {
+		m.fileX = addString(strings, m.File)
+		m.buildIDX = addString(strings, m.BuildID)
+	}
+
+	for _, l := range p.Location {
+		for i, ln := range l.Line {
+			if ln.Function != nil {
+				l.Line[i].functionIDX = ln.Function.ID
+			} else {
+				l.Line[i].functionIDX = 0
+			}
+		}
+		if l.Mapping != nil {
+			l.mappingIDX = l.Mapping.ID
+		} else {
+			l.mappingIDX = 0
+		}
+	}
+	for _, f := range p.Function {
+		f.nameX = addString(strings, f.Name)
+		f.systemNameX = addString(strings, f.SystemName)
+		f.filenameX = addString(strings, f.Filename)
+	}
+
+	if pt := p.PeriodType; pt != nil {
+		pt.typeX = addString(strings, pt.Type)
+		pt.unitX = addString(strings, pt.Unit)
+	}
+
+	p.stringTable = make([]string, len(strings))
+	for s, i := range strings {
+		p.stringTable[i] = s
+	}
+}
+
+func (p *Profile) encode(b *buffer) {
+	for _, x := range p.SampleType {
+		encodeMessage(b, 1, x)
+	}
+	for _, x := range p.Sample {
+		encodeMessage(b, 2, x)
+	}
+	for _, x := range p.Mapping {
+		encodeMessage(b, 3, x)
+	}
+	for _, x := range p.Location {
+		encodeMessage(b, 4, x)
+	}
+	for _, x := range p.Function {
+		encodeMessage(b, 5, x)
+	}
+	encodeStrings(b, 6, p.stringTable)
+	encodeInt64Opt(b, 9, p.TimeNanos)
+	encodeInt64Opt(b, 10, p.DurationNanos)
+	if pt := p.PeriodType; pt != nil && (pt.typeX != 0 || pt.unitX != 0) {
+		encodeMessage(b, 11, p.PeriodType)
+	}
+	encodeInt64Opt(b, 12, p.Period)
+}
+
+func (p *ValueType) encode(b *buffer) {
+	encodeInt64Opt(b, 1, p.typeX)
+	encodeInt64Opt(b, 2, p.unitX)
+}
+
+func (p *Sample) encode(b *buffer) {
+	encodeUint64s(b, 1, p.locationIDX)
+	for _, x := range p.Value {
+		encodeInt64(b, 2, x)
+	}
+	for _, x := range p.labelX {
+		encodeMessage(b, 3, x)
+	}
+}
+
+func (p Label) encode(b *buffer) {
+	encodeInt64Opt(b, 1, p.keyX)
+	encodeInt64Opt(b, 2, p.strX)
+	encodeInt64Opt(b, 3, p.numX)
+}
+
+func (p *Mapping) encode(b *buffer) {
+	encodeUint64Opt(b, 1, p.ID)
+	encodeUint64Opt(b, 2, p.Start)
+	encodeUint64Opt(b, 3, p.Limit)
+	encodeUint64Opt(b, 4, p.Offset)
+	encodeInt64Opt(b, 5, p.fileX)
+	encodeInt64Opt(b, 6, p.buildIDX)
+	encodeBoolOpt(b, 7, p.HasFunctions)
+	encodeBoolOpt(b, 8, p.HasFilenames)
+	encodeBoolOpt(b, 9, p.HasLineNumbers)
+	encodeBoolOpt(b, 10, p.HasInlineFrames)
+}
+
+func (p *Location) encode(b *buffer) {
+	encodeUint64Opt(b, 1, p.ID)
+	encodeUint64Opt(b, 2, p.mappingIDX)
+	encodeUint64Opt(b, 3, p.Address)
+	for i := range p.Line {
+		encodeMessage(b, 4, &p.Line[i])
+	}
+}
+
+func (p *Line) encode(b *buffer) {
+	encodeUint64Opt(b, 1, p.functionIDX)
+	encodeInt64Opt(b, 2, p.Line)
+}
+
+func (p *Function) encode(b *buffer) {
+	encodeUint64Opt(b, 1, p.ID)
+	encodeInt64Opt(b, 2, p.nameX)
+	encodeInt64Opt(b, 3, p.systemNameX)
+	encodeInt64Opt(b, 4, p.filenameX)
+	encodeInt64Opt(b, 5, p.StartLine)
+}
+
+func addString(strings map[string]int, s string) int64 {
+	i, ok := strings[s]
+	if !ok {
+		i = len(strings)
+		strings[s] = i
+	}
+	return int64(i)
+}
diff --git a/src/runtime/pprof/internal/profile/profile.go b/src/runtime/pprof/internal/profile/profile.go
new file mode 100644
index 0000000000..ef6ae39b65
--- /dev/null
+++ b/src/runtime/pprof/internal/profile/profile.go
@@ -0,0 +1,112 @@
+// Copyright 2016 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.
+//
+// Package profile provides a representation of profile.proto and
+// methods to encode/decode profiles in this format.
+package profile
+
+import (
+	"io"
+)
+
+// Profile is an in-memory representation of profile.proto.
+type Profile struct {
+	SampleType []*ValueType
+	Sample     []*Sample
+	Mapping    []*Mapping
+	Location   []*Location
+	Function   []*Function
+
+	TimeNanos     int64
+	DurationNanos int64
+	PeriodType    *ValueType
+	Period        int64
+
+	stringTable []string
+}
+
+// ValueType corresponds to Profile.ValueType
+type ValueType struct {
+	Type string // cpu, wall, inuse_space, etc
+	Unit string // seconds, nanoseconds, bytes, etc
+
+	typeX int64
+	unitX int64
+}
+
+// Sample corresponds to Profile.Sample
+type Sample struct {
+	Location []*Location
+	Value    []int64
+	Label    map[string][]string
+	NumLabel map[string][]int64
+
+	locationIDX []uint64
+	labelX      []Label
+}
+
+// Label corresponds to Profile.Label
+type Label struct {
+	keyX int64
+	// Exactly one of the two following values must be set
+	strX int64
+	numX int64 // Integer value for this label
+}
+
+// Mapping corresponds to Profile.Mapping
+type Mapping struct {
+	ID              uint64
+	Start           uint64
+	Limit           uint64
+	Offset          uint64
+	File            string
+	BuildID         string
+	HasFunctions    bool
+	HasFilenames    bool
+	HasLineNumbers  bool
+	HasInlineFrames bool
+
+	fileX    int64
+	buildIDX int64
+}
+
+// Location corresponds to Profile.Location
+type Location struct {
+	ID      uint64
+	Mapping *Mapping
+	Address uint64
+	Line    []Line
+
+	mappingIDX uint64
+}
+
+// Line corresponds to Profile.Line
+type Line struct {
+	Function *Function
+	Line     int64
+
+	functionIDX uint64
+}
+
+// Function corresponds to Profile.Function
+type Function struct {
+	ID         uint64
+	Name       string
+	SystemName string
+	Filename   string
+	StartLine  int64
+
+	nameX       int64
+	systemNameX int64
+	filenameX   int64
+}
+
+// Write writes the profile as a gzip-compressed marshaled protobuf.
+func (p *Profile) Write(w io.Writer) error {
+	p.preEncode()
+	var b buffer
+	p.encode(&b)
+	_, err := w.Write(b.data)
+	return err
+}
diff --git a/src/runtime/pprof/internal/profile/profile_memmap.go b/src/runtime/pprof/internal/profile/profile_memmap.go
new file mode 100644
index 0000000000..bb6cff60e0
--- /dev/null
+++ b/src/runtime/pprof/internal/profile/profile_memmap.go
@@ -0,0 +1,302 @@
+package profile
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"strconv"
+	"strings"
+)
+
+var errUnrecognized = errors.New("unrecognized profile format")
+
+func hasLibFile(file string) string {
+	ix := strings.Index(file, "so")
+	if ix < 1 {
+		return ""
+	}
+	start := ix - 1
+	end := ix + 2
+	s := file[start:end]
+	if end < len(file) {
+		endalt := end
+		if file[endalt] != '.' && file[endalt] != '_' {
+			return s
+		}
+		endalt++
+		for file[endalt] >= '0' && file[endalt] <= '9' {
+			endalt++
+		}
+		if endalt < end+2 {
+			return s
+		}
+		return s[start:endalt]
+	}
+	return s
+}
+
+// massageMappings applies heuristic-based changes to the profile
+// mappings to account for quirks of some environments.
+func (p *Profile) massageMappings() {
+	// Merge adjacent regions with matching names, checking that the offsets match
+	if len(p.Mapping) > 1 {
+		mappings := []*Mapping{p.Mapping[0]}
+		for _, m := range p.Mapping[1:] {
+			lm := mappings[len(mappings)-1]
+			if offset := lm.Offset + (lm.Limit - lm.Start); lm.Limit == m.Start &&
+				offset == m.Offset &&
+				(lm.File == m.File || lm.File == "") {
+				lm.File = m.File
+				lm.Limit = m.Limit
+				if lm.BuildID == "" {
+					lm.BuildID = m.BuildID
+				}
+				p.updateLocationMapping(m, lm)
+				continue
+			}
+			mappings = append(mappings, m)
+		}
+		p.Mapping = mappings
+	}
+
+	// Use heuristics to identify main binary and move it to the top of the list of mappings
+	for i, m := range p.Mapping {
+		file := strings.TrimSpace(strings.Replace(m.File, "(deleted)", "", -1))
+		if len(file) == 0 {
+			continue
+		}
+		if len(hasLibFile(file)) > 0 {
+			continue
+		}
+		if strings.HasPrefix(file, "[") {
+			continue
+		}
+		// Swap what we guess is main to position 0.
+		p.Mapping[0], p.Mapping[i] = p.Mapping[i], p.Mapping[0]
+		break
+	}
+
+	// Keep the mapping IDs neatly sorted
+	for i, m := range p.Mapping {
+		m.ID = uint64(i + 1)
+	}
+}
+
+func (p *Profile) updateLocationMapping(from, to *Mapping) {
+	for _, l := range p.Location {
+		if l.Mapping == from {
+			l.Mapping = to
+		}
+	}
+}
+
+// remapLocationIDs ensures there is a location for each address
+// referenced by a sample, and remaps the samples to point to the new
+// location ids.
+func (p *Profile) remapLocationIDs() {
+	seen := make(map[*Location]bool, len(p.Location))
+	var locs []*Location
+
+	for _, s := range p.Sample {
+		for _, l := range s.Location {
+			if seen[l] {
+				continue
+			}
+			l.ID = uint64(len(locs) + 1)
+			locs = append(locs, l)
+			seen[l] = true
+		}
+	}
+	p.Location = locs
+}
+
+func (p *Profile) remapFunctionIDs() {
+	seen := make(map[*Function]bool, len(p.Function))
+	var fns []*Function
+
+	for _, l := range p.Location {
+		for _, ln := range l.Line {
+			fn := ln.Function
+			if fn == nil || seen[fn] {
+				continue
+			}
+			fn.ID = uint64(len(fns) + 1)
+			fns = append(fns, fn)
+			seen[fn] = true
+		}
+	}
+	p.Function = fns
+}
+
+// remapMappingIDs matches location addresses with existing mappings
+// and updates them appropriately. This is O(N*M), if this ever shows
+// up as a bottleneck, evaluate sorting the mappings and doing a
+// binary search, which would make it O(N*log(M)).
+func (p *Profile) remapMappingIDs() {
+	// Some profile handlers will incorrectly set regions for the main
+	// executable if its section is remapped. Fix them through heuristics.
+
+	if len(p.Mapping) > 0 {
+		// Remove the initial mapping if named '/anon_hugepage' and has a
+		// consecutive adjacent mapping.
+		if m := p.Mapping[0]; strings.HasPrefix(m.File, "/anon_hugepage") {
+			if len(p.Mapping) > 1 && m.Limit == p.Mapping[1].Start {
+				p.Mapping = p.Mapping[1:]
+			}
+		}
+	}
+
+	// Subtract the offset from the start of the main mapping if it
+	// ends up at a recognizable start address.
+	if len(p.Mapping) > 0 {
+		const expectedStart = 0x400000
+		if m := p.Mapping[0]; m.Start-m.Offset == expectedStart {
+			m.Start = expectedStart
+			m.Offset = 0
+		}
+	}
+
+	// Associate each location with an address to the corresponding
+	// mapping. Create fake mapping if a suitable one isn't found.
+	var fake *Mapping
+nextLocation:
+	for _, l := range p.Location {
+		a := l.Address
+		if l.Mapping != nil || a == 0 {
+			continue
+		}
+		for _, m := range p.Mapping {
+			if m.Start <= a && a < m.Limit {
+				l.Mapping = m
+				continue nextLocation
+			}
+		}
+		// Work around legacy handlers failing to encode the first
+		// part of mappings split into adjacent ranges.
+		for _, m := range p.Mapping {
+			if m.Offset != 0 && m.Start-m.Offset <= a && a < m.Start {
+				m.Start -= m.Offset
+				m.Offset = 0
+				l.Mapping = m
+				continue nextLocation
+			}
+		}
+		// If there is still no mapping, create a fake one.
+		// This is important for the Go legacy handler, which produced
+		// no mappings.
+		if fake == nil {
+			fake = &Mapping{
+				ID:    1,
+				Limit: ^uint64(0),
+			}
+			p.Mapping = append(p.Mapping, fake)
+		}
+		l.Mapping = fake
+	}
+
+	// Reset all mapping IDs.
+	for i, m := range p.Mapping {
+		m.ID = uint64(i + 1)
+	}
+}
+
+func (p *Profile) RemapAll() {
+	p.remapLocationIDs()
+	p.remapFunctionIDs()
+	p.remapMappingIDs()
+}
+
+// ParseProcMaps parses a memory map in the format of /proc/self/maps.
+// ParseMemoryMap should be called after setting on a profile to
+// associate locations to the corresponding mapping based on their
+// address.
+func ParseProcMaps(rd io.Reader) ([]*Mapping, error) {
+	var mapping []*Mapping
+
+	b := bufio.NewReader(rd)
+
+	var attrs []string
+	var r *strings.Replacer
+	const delimiter = "="
+	for {
+		l, err := b.ReadString('\n')
+		if err != nil {
+			if err != io.EOF {
+				return nil, err
+			}
+			if l == "" {
+				break
+			}
+		}
+		if l = strings.TrimSpace(l); l == "" {
+			continue
+		}
+
+		if r != nil {
+			l = r.Replace(l)
+		}
+		m, err := parseMappingEntry(l)
+		if err != nil {
+			if err == errUnrecognized {
+				// Recognize assignments of the form: attr=value, and replace
+				// $attr with value on subsequent mappings.
+				if attr := strings.SplitN(l, delimiter, 2); len(attr) == 2 {
+					attrs = append(attrs, "$"+strings.TrimSpace(attr[0]), strings.TrimSpace(attr[1]))
+					r = strings.NewReplacer(attrs...)
+				}
+				// Ignore any unrecognized entries
+				continue
+			}
+			return nil, err
+		}
+		if m == nil {
+			continue
+		}
+		mapping = append(mapping, m)
+	}
+	return mapping, nil
+}
+
+// ParseMemoryMap parses a memory map in the format of
+// /proc/self/maps, and overrides the mappings in the current profile.
+// It renumbers the samples and locations in the profile correspondingly.
+func (p *Profile) ParseMemoryMap(rd io.Reader) error {
+	mapping, err := ParseProcMaps(rd)
+	if err != nil {
+		return err
+	}
+	p.Mapping = append(p.Mapping, mapping...)
+	p.massageMappings()
+	p.RemapAll()
+	return nil
+}
+
+func parseMappingEntry(l string) (*Mapping, error) {
+	mapping := &Mapping{}
+	var err error
+	fields := strings.Fields(l)
+	// fmt.Println(len(me), me)
+	if len(fields) == 6 {
+		if !strings.Contains(fields[1], "x") {
+			// Skip non-executable entries.
+			return nil, nil
+		}
+		addrRange := strings.Split(fields[0], "-")
+		if mapping.Start, err = strconv.ParseUint(addrRange[0], 16, 64); err != nil {
+			return nil, errUnrecognized
+		}
+		if mapping.Limit, err = strconv.ParseUint(addrRange[1], 16, 64); err != nil {
+			return nil, errUnrecognized
+		}
+		offset := fields[2]
+		if offset != "" {
+			if mapping.Offset, err = strconv.ParseUint(offset, 16, 64); err != nil {
+				return nil, errUnrecognized
+			}
+		}
+		mapping.File = fields[5]
+		return mapping, nil
+	}
+
+	return nil, errUnrecognized
+}
diff --git a/src/runtime/pprof/internal/profile/proto.go b/src/runtime/pprof/internal/profile/proto.go
new file mode 100644
index 0000000000..ce1074ba4c
--- /dev/null
+++ b/src/runtime/pprof/internal/profile/proto.go
@@ -0,0 +1,156 @@
+// Copyright 2014 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.
+//
+// This file is a simple protocol buffer encoder and decoder.
+//
+// A protocol message must implement the message interface:
+//   decoder() []decoder
+//   encode(*buffer)
+//
+// The decode method returns a slice indexed by field number that gives the
+// function to decode that field.
+// The encode method encodes its receiver into the given buffer.
+//
+// The two methods are simple enough to be implemented by hand rather than
+// by using a protocol compiler.
+//
+// See profile.go for examples of messages implementing this interface.
+//
+// There is no support for groups, message sets, or "has" bits.
+
+package profile
+
+type buffer struct {
+	field int
+	typ   int
+	u64   uint64
+	data  []byte
+	tmp   [16]byte
+}
+
+type message interface {
+	encode(*buffer)
+}
+
+func encodeVarint(b *buffer, x uint64) {
+	for x >= 128 {
+		b.data = append(b.data, byte(x)|0x80)
+		x >>= 7
+	}
+	b.data = append(b.data, byte(x))
+}
+
+func encodeLength(b *buffer, tag int, len int) {
+	encodeVarint(b, uint64(tag)<<3|2)
+	encodeVarint(b, uint64(len))
+}
+
+func encodeUint64(b *buffer, tag int, x uint64) {
+	// append varint to b.data
+	encodeVarint(b, uint64(tag)<<3|0)
+	encodeVarint(b, x)
+}
+
+func encodeUint64s(b *buffer, tag int, x []uint64) {
+	if len(x) > 2 {
+		// Use packed encoding
+		n1 := len(b.data)
+		for _, u := range x {
+			encodeVarint(b, u)
+		}
+		n2 := len(b.data)
+		encodeLength(b, tag, n2-n1)
+		n3 := len(b.data)
+		copy(b.tmp[:], b.data[n2:n3])
+		copy(b.data[n1+(n3-n2):], b.data[n1:n2])
+		copy(b.data[n1:], b.tmp[:n3-n2])
+		return
+	}
+	for _, u := range x {
+		encodeUint64(b, tag, u)
+	}
+}
+
+func encodeUint64Opt(b *buffer, tag int, x uint64) {
+	if x == 0 {
+		return
+	}
+	encodeUint64(b, tag, x)
+}
+
+func encodeInt64(b *buffer, tag int, x int64) {
+	u := uint64(x)
+	encodeUint64(b, tag, u)
+}
+
+func encodeInt64Opt(b *buffer, tag int, x int64) {
+	if x == 0 {
+		return
+	}
+	encodeInt64(b, tag, x)
+}
+
+func encodeInt64s(b *buffer, tag int, x []int64) {
+	if len(x) > 2 {
+		// Use packed encoding
+		n1 := len(b.data)
+		for _, u := range x {
+			encodeVarint(b, uint64(u))
+		}
+		n2 := len(b.data)
+		encodeLength(b, tag, n2-n1)
+		n3 := len(b.data)
+		copy(b.tmp[:], b.data[n2:n3])
+		copy(b.data[n1+(n3-n2):], b.data[n1:n2])
+		copy(b.data[n1:], b.tmp[:n3-n2])
+		return
+	}
+	for _, u := range x {
+		encodeInt64(b, tag, u)
+	}
+}
+
+func encodeString(b *buffer, tag int, x string) {
+	encodeLength(b, tag, len(x))
+	b.data = append(b.data, x...)
+}
+
+func encodeStrings(b *buffer, tag int, x []string) {
+	for _, s := range x {
+		encodeString(b, tag, s)
+	}
+}
+
+func encodeStringOpt(b *buffer, tag int, x string) {
+	if x == "" {
+		return
+	}
+	encodeString(b, tag, x)
+}
+
+func encodeBool(b *buffer, tag int, x bool) {
+	if x {
+		encodeUint64(b, tag, 1)
+	} else {
+		encodeUint64(b, tag, 0)
+	}
+}
+
+func encodeBoolOpt(b *buffer, tag int, x bool) {
+	if x == false {
+		return
+	}
+	encodeBool(b, tag, x)
+}
+
+func encodeMessage(b *buffer, tag int, m message) {
+	n1 := len(b.data)
+	m.encode(b)
+	n2 := len(b.data)
+	encodeLength(b, tag, n2-n1)
+	n3 := len(b.data)
+	copy(b.tmp[:], b.data[n2:n3])
+	copy(b.data[n1+(n3-n2):], b.data[n1:n2])
+	copy(b.data[n1:], b.tmp[:n3-n2])
+}
diff --git a/src/runtime/pprof/internal/protopprof/protopprof.go b/src/runtime/pprof/internal/protopprof/protopprof.go
new file mode 100644
index 0000000000..ac28ec2109
--- /dev/null
+++ b/src/runtime/pprof/internal/protopprof/protopprof.go
@@ -0,0 +1,295 @@
+// Copyright 2016 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.
+package protopprof
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"strings"
+	"time"
+
+	"runtime/pprof/internal/profile"
+)
+
+// Copied from encoding/binary package, which can't be imported due to
+// dependency cycles
+
+// LittleEndian is the little-endian implementation of ByteOrder.
+var lEndian littleEndian
+
+// BigEndian is the big-endian implementation of ByteOrder.
+var bEndian bigEndian
+
+type littleEndian struct{}
+type bigEndian struct{}
+
+func (bigEndian) uint32(b []byte) uint32 {
+	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
+}
+
+func (bigEndian) uint64(b []byte) uint64 {
+	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
+		uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
+}
+
+func (littleEndian) uint32(b []byte) uint32 {
+	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func (littleEndian) uint64(b []byte) uint64 {
+	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}
+
+func big32(b []byte) (uint64, []byte) {
+	if len(b) < 4 {
+		return 0, nil
+	}
+	return uint64(bEndian.uint32(b)), b[4:]
+}
+
+func little32(b []byte) (uint64, []byte) {
+	if len(b) < 4 {
+		return 0, nil
+	}
+	return uint64(lEndian.uint32(b)), b[4:]
+}
+
+func big64(b []byte) (uint64, []byte) {
+	if len(b) < 8 {
+		return 0, nil
+	}
+	return bEndian.uint64(b), b[8:]
+}
+
+func little64(b []byte) (uint64, []byte) {
+	if len(b) < 8 {
+		return 0, nil
+	}
+	return lEndian.uint64(b), b[8:]
+}
+
+// End of copy from encoding/binary package
+
+type parser func([]byte) (uint64, []byte)
+
+var parsers = []parser{
+	big32,
+	big64,
+	little32,
+	little64,
+}
+
+// parse returns a parsing function to parse native integers from a buffer.
+func findParser(b []byte) parser {
+	for _, p := range parsers {
+		// If the second word decodes as 3, we have the right parser.
+		_, rest := p(b) // first word
+		n, _ := p(rest) // second word
+		if n == 3 {
+			return p
+		}
+	}
+	return nil
+}
+
+// decodeHeader parses binary CPU profiling stack trace data
+// generated by runtime.CPUProfile() and returns the sample period,
+// the rest of the profile and a parse function for parsing the profile. The
+// function detects whether the legacy profile format is in little or big
+// endian and whether it was generated by a 32-bit or 64-bit machine.
+func decodeHeader(b []byte) (period uint64, parse parser, rest []byte, err error) {
+	const minRawProfile = 12 // Need a minimum of 3 words, at least 32-bit each.
+	if len(b) < minRawProfile {
+		return 0, nil, nil, fmt.Errorf("truncated raw profile: len %d", len(b))
+	}
+	if parse = findParser(b); parse == nil {
+		return 0, nil, nil, fmt.Errorf("cannot parse raw profile: header %v", b[:minRawProfile])
+	}
+	// skip 5-word header; 4th word is period
+	_, rest = parse(b)
+	_, rest = parse(rest)
+	_, rest = parse(rest)
+	period, rest = parse(rest)
+	_, rest = parse(rest)
+	if rest == nil {
+		return 0, nil, nil, fmt.Errorf("profile too short")
+	}
+	return period, parse, rest, nil
+}
+
+// translateCPUProfile parses binary CPU profiling stack trace data
+// generated by runtime.CPUProfile() into a profile struct.
+func TranslateCPUProfile(b []byte, startTime time.Time) (*profile.Profile, error) {
+	// Get the sample period from the header.
+	var n4 uint64
+	var getInt parser
+	var err error
+	n4, getInt, b, err = decodeHeader(b)
+	if err != nil {
+		return nil, err
+	}
+
+	// profile initialization taken from pprof tool
+	p := &profile.Profile{
+		Period:     int64(n4) * 1000,
+		PeriodType: &profile.ValueType{Type: "cpu", Unit: "nanoseconds"},
+		SampleType: []*profile.ValueType{
+			{Type: "samples", Unit: "count"},
+			{Type: "cpu", Unit: "nanoseconds"},
+		},
+		TimeNanos:     int64(startTime.UnixNano()),
+		DurationNanos: time.Since(startTime).Nanoseconds(),
+	}
+	// Parse CPU samples from the profile.
+	locs := make(map[uint64]*profile.Location)
+	for len(b) > 0 {
+		var count, nstk uint64
+		count, b = getInt(b)
+		nstk, b = getInt(b)
+		if b == nil {
+			return nil, fmt.Errorf("unrecognized profile format")
+		}
+		var sloc []*profile.Location
+		addrs := make([]uint64, nstk)
+
+		for i := 0; i < int(nstk); i++ {
+			if b == nil {
+				return nil, fmt.Errorf("unrecognized profile format")
+			}
+			addrs[i], b = getInt(b)
+		}
+		// End of data marker, can return
+		if count == 0 && nstk == 1 && addrs[0] == 0 {
+			if runtime.GOOS == "linux" {
+				if err := addMappings(p); err != nil {
+					return nil, err
+				}
+			}
+			return p, nil
+		}
+		for i, addr := range addrs {
+			// Addresses from stack traces point to the next instruction after
+			// each call.  Adjust by -1 to land somewhere on the actual call
+			// (except for the leaf, which is not a call).
+			if i > 0 {
+				addr--
+			}
+			loc := locs[addr]
+			if loc == nil {
+				loc = &profile.Location{
+					ID:      uint64(len(p.Location) + 1),
+					Address: addr,
+				}
+				locs[addr] = loc
+				p.Location = append(p.Location, loc)
+			}
+			sloc = append(sloc, loc)
+		}
+		p.Sample = append(p.Sample, &profile.Sample{
+			Value:    []int64{int64(count), int64(count) * int64(p.Period)},
+			Location: sloc,
+		})
+	}
+
+	return nil, fmt.Errorf("unrecognized profile format")
+}
+
+func addMappings(p *profile.Profile) error {
+	// Parse memory map from /proc/self/maps
+	f, err := os.Open("/proc/self/maps")
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	return p.ParseMemoryMap(f)
+}
+
+// Symbolization enables adding names to locations.
+func Symbolize(p *profile.Profile) {
+	fns := profileFunctionMap{}
+	for _, l := range p.Location {
+		pc := uintptr(l.Address)
+		f := runtime.FuncForPC(pc)
+		if f == nil {
+			continue
+		}
+		file, lineno := f.FileLine(pc)
+		if l.Mapping != nil {
+			if f.Name() != "" {
+				l.Mapping.HasFunctions = true
+			}
+			if file != "" {
+				l.Mapping.HasFilenames = true
+			}
+			if lineno != 0 {
+				l.Mapping.HasLineNumbers = true
+			}
+		}
+		l.Line = []profile.Line{
+			{
+				Function: fns.findOrAddFunction(f.Name(), file, p),
+				Line:     int64(lineno),
+			},
+		}
+	}
+
+	// Trim runtime functions. Always hide runtime.goexit. Other runtime
+	// functions are only hidden for heapz when they appear at the beginning.
+	isHeapz := p.PeriodType != nil && p.PeriodType.Type == "space"
+	for _, s := range p.Sample {
+		show := !isHeapz
+		var i int
+		for _, l := range s.Location {
+			if (len(l.Line) > 0) && (l.Line[0].Function != nil) {
+				name := l.Line[0].Function.Name
+				if (name == "runtime.goexit") || (!show && strings.HasPrefix(name, "runtime.")) {
+					continue
+				}
+			}
+			show = true
+			s.Location[i] = l
+			i++
+		}
+		s.Location = s.Location[:i]
+	}
+}
+
+type profileFunctionMap map[profile.Function]*profile.Function
+
+func (fns profileFunctionMap) findOrAddFunction(name, filename string, p *profile.Profile) *profile.Function {
+	f := profile.Function{
+		Name:       name,
+		SystemName: name,
+		Filename:   filename,
+	}
+	if fp := fns[f]; fp != nil {
+		return fp
+	}
+	fp := new(profile.Function)
+	fns[f] = fp
+
+	*fp = f
+	fp.ID = uint64(len(p.Function) + 1)
+	p.Function = append(p.Function, fp)
+	return fp
+}
+
+func CleanupDuplicateLocations(p *profile.Profile) {
+	// The profile handler may duplicate the leaf frame, because it gets
+	// its address both from stack unwinding and from the signal
+	// context. Detect this and delete the duplicate, which has been
+	// adjusted by -1. The leaf address should not be adjusted as it is
+	// not a call.
+	for _, s := range p.Sample {
+		if len(s.Location) > 1 && s.Location[0].Address == s.Location[1].Address+1 {
+			s.Location = append(s.Location[:1], s.Location[2:]...)
+		}
+	}
+}