vendor: cilium/ebbf 4032b1d8aae306b7bb94a2a11002932caf88c644

full diff: 60c3aa43f4...4032b1d8aa

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor/github.com/cilium/ebpf/internal/btf/btf.go

@@ -0,0 +1,530 @@
+package btf
+
+import (
+	"bytes"
+	"debug/elf"
+	"encoding/binary"
+	"io"
+	"io/ioutil"
+	"math"
+	"reflect"
+	"unsafe"
+
+	"github.com/cilium/ebpf/internal"
+	"github.com/cilium/ebpf/internal/unix"
+
+	"github.com/pkg/errors"
+)
+
+const btfMagic = 0xeB9F
+
+// Spec represents decoded BTF.
+type Spec struct {
+	rawTypes  []rawType
+	strings   stringTable
+	types     map[string][]Type
+	funcInfos map[string]extInfo
+	lineInfos map[string]extInfo
+}
+
+type btfHeader struct {
+	Magic   uint16
+	Version uint8
+	Flags   uint8
+	HdrLen  uint32
+
+	TypeOff   uint32
+	TypeLen   uint32
+	StringOff uint32
+	StringLen uint32
+}
+
+// LoadSpecFromReader reads BTF sections from an ELF.
+//
+// Returns a nil Spec and no error if no BTF was present.
+func LoadSpecFromReader(rd io.ReaderAt) (*Spec, error) {
+	file, err := elf.NewFile(rd)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	var (
+		btfSection    *elf.Section
+		btfExtSection *elf.Section
+	)
+
+	for _, sec := range file.Sections {
+		switch sec.Name {
+		case ".BTF":
+			btfSection = sec
+		case ".BTF.ext":
+			btfExtSection = sec
+		}
+	}
+
+	if btfSection == nil {
+		return nil, nil
+	}
+
+	spec, err := parseBTF(btfSection.Open(), file.ByteOrder)
+	if err != nil {
+		return nil, err
+	}
+
+	if btfExtSection != nil {
+		spec.funcInfos, spec.lineInfos, err = parseExtInfos(btfExtSection.Open(), file.ByteOrder, spec.strings)
+		if err != nil {
+			return nil, errors.Wrap(err, "can't read ext info")
+		}
+	}
+
+	return spec, nil
+}
+
+func parseBTF(btf io.ReadSeeker, bo binary.ByteOrder) (*Spec, error) {
+	rawBTF, err := ioutil.ReadAll(btf)
+	if err != nil {
+		return nil, errors.Wrap(err, "can't read BTF")
+	}
+
+	rd := bytes.NewReader(rawBTF)
+
+	var header btfHeader
+	if err := binary.Read(rd, bo, &header); err != nil {
+		return nil, errors.Wrap(err, "can't read header")
+	}
+
+	if header.Magic != btfMagic {
+		return nil, errors.Errorf("incorrect magic value %v", header.Magic)
+	}
+
+	if header.Version != 1 {
+		return nil, errors.Errorf("unexpected version %v", header.Version)
+	}
+
+	if header.Flags != 0 {
+		return nil, errors.Errorf("unsupported flags %v", header.Flags)
+	}
+
+	remainder := int64(header.HdrLen) - int64(binary.Size(&header))
+	if remainder < 0 {
+		return nil, errors.New("header is too short")
+	}
+
+	if _, err := io.CopyN(internal.DiscardZeroes{}, rd, remainder); err != nil {
+		return nil, errors.Wrap(err, "header padding")
+	}
+
+	if _, err := rd.Seek(int64(header.HdrLen+header.StringOff), io.SeekStart); err != nil {
+		return nil, errors.Wrap(err, "can't seek to start of string section")
+	}
+
+	strings, err := readStringTable(io.LimitReader(rd, int64(header.StringLen)))
+	if err != nil {
+		return nil, errors.Wrap(err, "can't read type names")
+	}
+
+	if _, err := rd.Seek(int64(header.HdrLen+header.TypeOff), io.SeekStart); err != nil {
+		return nil, errors.Wrap(err, "can't seek to start of type section")
+	}
+
+	rawTypes, err := readTypes(io.LimitReader(rd, int64(header.TypeLen)), bo)
+	if err != nil {
+		return nil, errors.Wrap(err, "can't read types")
+	}
+
+	types, err := inflateRawTypes(rawTypes, strings)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Spec{
+		rawTypes:  rawTypes,
+		types:     types,
+		strings:   strings,
+		funcInfos: make(map[string]extInfo),
+		lineInfos: make(map[string]extInfo),
+	}, nil
+}
+
+func (s *Spec) marshal(bo binary.ByteOrder) ([]byte, error) {
+	var (
+		buf       bytes.Buffer
+		header    = new(btfHeader)
+		headerLen = binary.Size(header)
+	)
+
+	// Reserve space for the header. We have to write it last since
+	// we don't know the size of the type section yet.
+	_, _ = buf.Write(make([]byte, headerLen))
+
+	// Write type section, just after the header.
+	for _, typ := range s.rawTypes {
+		if typ.Kind() == kindDatasec {
+			// Datasec requires patching with information from the ELF
+			// file. We don't support this at the moment, so patch
+			// out any Datasec by turning it into a void*.
+			typ = rawType{}
+			typ.SetKind(kindPointer)
+		}
+
+		if err := typ.Marshal(&buf, bo); err != nil {
+			return nil, errors.Wrap(err, "can't marshal BTF")
+		}
+	}
+
+	typeLen := uint32(buf.Len() - headerLen)
+
+	// Write string section after type section.
+	_, _ = buf.Write(s.strings)
+
+	// Fill out the header, and write it out.
+	header = &btfHeader{
+		Magic:     btfMagic,
+		Version:   1,
+		Flags:     0,
+		HdrLen:    uint32(headerLen),
+		TypeOff:   0,
+		TypeLen:   typeLen,
+		StringOff: typeLen,
+		StringLen: uint32(len(s.strings)),
+	}
+
+	raw := buf.Bytes()
+	err := binary.Write(sliceWriter(raw[:headerLen]), bo, header)
+	if err != nil {
+		return nil, errors.Wrap(err, "can't write header")
+	}
+
+	return raw, nil
+}
+
+type sliceWriter []byte
+
+func (sw sliceWriter) Write(p []byte) (int, error) {
+	if len(p) != len(sw) {
+		return 0, errors.New("size doesn't match")
+	}
+
+	return copy(sw, p), nil
+}
+
+// Program finds the BTF for a specific section.
+//
+// Length is the number of bytes in the raw BPF instruction stream.
+//
+// Returns an error if there is no BTF.
+func (s *Spec) Program(name string, length uint64) (*Program, error) {
+	if length == 0 {
+		return nil, errors.New("length musn't be zero")
+	}
+
+	funcInfos, funcOK := s.funcInfos[name]
+	lineInfos, lineOK := s.lineInfos[name]
+
+	if !funcOK && !lineOK {
+		return nil, errors.Errorf("no BTF for program %s", name)
+	}
+
+	return &Program{s, length, funcInfos, lineInfos}, nil
+}
+
+// Map finds the BTF for a map.
+//
+// Returns an error if there is no BTF for the given name.
+func (s *Spec) Map(name string) (*Map, error) {
+	var mapVar Var
+	if err := s.FindType(name, &mapVar); err != nil {
+		return nil, err
+	}
+
+	mapStruct, ok := mapVar.Type.(*Struct)
+	if !ok {
+		return nil, errors.Errorf("expected struct, have %s", mapVar.Type)
+	}
+
+	var key, value Type
+	for _, member := range mapStruct.Members {
+		switch member.Name {
+		case "key":
+			key = member.Type
+
+		case "value":
+			value = member.Type
+		}
+	}
+
+	if key == nil {
+		return nil, errors.Errorf("map %s: missing 'key' in type", name)
+	}
+
+	if value == nil {
+		return nil, errors.Errorf("map %s: missing 'value' in type", name)
+	}
+
+	return &Map{mapStruct, s, key, value}, nil
+}
+
+var errNotFound = errors.New("not found")
+
+// FindType searches for a type with a specific name.
+//
+// hint determines the type of the returned Type.
+//
+// Returns an error if there is no or multiple matches.
+func (s *Spec) FindType(name string, typ Type) error {
+	var (
+		wanted    = reflect.TypeOf(typ)
+		candidate Type
+	)
+
+	for _, typ := range s.types[name] {
+		if reflect.TypeOf(typ) != wanted {
+			continue
+		}
+
+		if candidate != nil {
+			return errors.Errorf("type %s: multiple candidates for %T", name, typ)
+		}
+
+		candidate = typ
+	}
+
+	if candidate == nil {
+		return errors.WithMessagef(errNotFound, "type %s", name)
+	}
+
+	value := reflect.Indirect(reflect.ValueOf(copyType(candidate)))
+	reflect.Indirect(reflect.ValueOf(typ)).Set(value)
+	return nil
+}
+
+// Handle is a reference to BTF loaded into the kernel.
+type Handle struct {
+	fd *internal.FD
+}
+
+// NewHandle loads BTF into the kernel.
+//
+// Returns an error if BTF is not supported, which can
+// be checked by IsNotSupported.
+func NewHandle(spec *Spec) (*Handle, error) {
+	if err := haveBTF(); err != nil {
+		return nil, err
+	}
+
+	btf, err := spec.marshal(internal.NativeEndian)
+	if err != nil {
+		return nil, errors.Wrap(err, "can't marshal BTF")
+	}
+
+	if uint64(len(btf)) > math.MaxUint32 {
+		return nil, errors.New("BTF exceeds the maximum size")
+	}
+
+	attr := &bpfLoadBTFAttr{
+		btf:     internal.NewSlicePointer(btf),
+		btfSize: uint32(len(btf)),
+	}
+
+	fd, err := bpfLoadBTF(attr)
+	if err != nil {
+		logBuf := make([]byte, 64*1024)
+		attr.logBuf = internal.NewSlicePointer(logBuf)
+		attr.btfLogSize = uint32(len(logBuf))
+		attr.btfLogLevel = 1
+		_, logErr := bpfLoadBTF(attr)
+		return nil, internal.ErrorWithLog(err, logBuf, logErr)
+	}
+
+	return &Handle{fd}, nil
+}
+
+// Close destroys the handle.
+//
+// Subsequent calls to FD will return an invalid value.
+func (h *Handle) Close() error {
+	return h.fd.Close()
+}
+
+// FD returns the file descriptor for the handle.
+func (h *Handle) FD() int {
+	value, err := h.fd.Value()
+	if err != nil {
+		return -1
+	}
+
+	return int(value)
+}
+
+// Map is the BTF for a map.
+type Map struct {
+	definition *Struct
+	spec       *Spec
+	key, value Type
+}
+
+// MapSpec should be a method on Map, but is a free function
+// to hide it from users of the ebpf package.
+func MapSpec(m *Map) *Spec {
+	return m.spec
+}
+
+// MapType should be a method on Map, but is a free function
+// to hide it from users of the ebpf package.
+func MapType(m *Map) *Struct {
+	return m.definition
+}
+
+// MapKey should be a method on Map, but is a free function
+// to hide it from users of the ebpf package.
+func MapKey(m *Map) Type {
+	return m.key
+}
+
+// MapValue should be a method on Map, but is a free function
+// to hide it from users of the ebpf package.
+func MapValue(m *Map) Type {
+	return m.value
+}
+
+// Program is the BTF information for a stream of instructions.
+type Program struct {
+	spec                 *Spec
+	length               uint64
+	funcInfos, lineInfos extInfo
+}
+
+// ProgramSpec returns the Spec needed for loading function and line infos into the kernel.
+//
+// This is a free function instead of a method to hide it from users
+// of package ebpf.
+func ProgramSpec(s *Program) *Spec {
+	return s.spec
+}
+
+// ProgramAppend the information from other to the Program.
+//
+// This is a free function instead of a method to hide it from users
+// of package ebpf.
+func ProgramAppend(s, other *Program) error {
+	funcInfos, err := s.funcInfos.append(other.funcInfos, s.length)
+	if err != nil {
+		return errors.Wrap(err, "func infos")
+	}
+
+	lineInfos, err := s.lineInfos.append(other.lineInfos, s.length)
+	if err != nil {
+		return errors.Wrap(err, "line infos")
+	}
+
+	s.length += other.length
+	s.funcInfos = funcInfos
+	s.lineInfos = lineInfos
+	return nil
+}
+
+// ProgramFuncInfos returns the binary form of BTF function infos.
+//
+// This is a free function instead of a method to hide it from users
+// of package ebpf.
+func ProgramFuncInfos(s *Program) (recordSize uint32, bytes []byte, err error) {
+	bytes, err = s.funcInfos.MarshalBinary()
+	if err != nil {
+		return 0, nil, err
+	}
+
+	return s.funcInfos.recordSize, bytes, nil
+}
+
+// ProgramLineInfos returns the binary form of BTF line infos.
+//
+// This is a free function instead of a method to hide it from users
+// of package ebpf.
+func ProgramLineInfos(s *Program) (recordSize uint32, bytes []byte, err error) {
+	bytes, err = s.lineInfos.MarshalBinary()
+	if err != nil {
+		return 0, nil, err
+	}
+
+	return s.lineInfos.recordSize, bytes, nil
+}
+
+// IsNotSupported returns true if the error indicates that the kernel
+// doesn't support BTF.
+func IsNotSupported(err error) bool {
+	ufe, ok := errors.Cause(err).(*internal.UnsupportedFeatureError)
+	return ok && ufe.Name == "BTF"
+}
+
+type bpfLoadBTFAttr struct {
+	btf         internal.Pointer
+	logBuf      internal.Pointer
+	btfSize     uint32
+	btfLogSize  uint32
+	btfLogLevel uint32
+}
+
+func bpfLoadBTF(attr *bpfLoadBTFAttr) (*internal.FD, error) {
+	const _BTFLoad = 18
+
+	fd, err := internal.BPF(_BTFLoad, unsafe.Pointer(attr), unsafe.Sizeof(*attr))
+	if err != nil {
+		return nil, err
+	}
+
+	return internal.NewFD(uint32(fd)), nil
+}
+
+func minimalBTF(bo binary.ByteOrder) []byte {
+	const minHeaderLength = 24
+
+	var (
+		types struct {
+			Integer btfType
+			Var     btfType
+			btfVar  struct{ Linkage uint32 }
+		}
+		typLen  = uint32(binary.Size(&types))
+		strings = []byte{0, 'a', 0}
+		header  = btfHeader{
+			Magic:     btfMagic,
+			Version:   1,
+			HdrLen:    minHeaderLength,
+			TypeOff:   0,
+			TypeLen:   typLen,
+			StringOff: typLen,
+			StringLen: uint32(len(strings)),
+		}
+	)
+
+	// We use a BTF_KIND_VAR here, to make sure that
+	// the kernel understands BTF at least as well as we
+	// do. BTF_KIND_VAR was introduced ~5.1.
+	types.Integer.SetKind(kindPointer)
+	types.Var.NameOff = 1
+	types.Var.SetKind(kindVar)
+	types.Var.SizeType = 1
+
+	buf := new(bytes.Buffer)
+	_ = binary.Write(buf, bo, &header)
+	_ = binary.Write(buf, bo, &types)
+	buf.Write(strings)
+
+	return buf.Bytes()
+}
+
+var haveBTF = internal.FeatureTest("BTF", "5.1", func() bool {
+	btf := minimalBTF(internal.NativeEndian)
+	fd, err := bpfLoadBTF(&bpfLoadBTFAttr{
+		btf:     internal.NewSlicePointer(btf),
+		btfSize: uint32(len(btf)),
+	})
+	if err == nil {
+		fd.Close()
+	}
+	// Check for EINVAL specifically, rather than err != nil since we
+	// otherwise misdetect due to insufficient permissions.
+	return errors.Cause(err) != unix.EINVAL
+})

vendor/github.com/cilium/ebpf/internal/btf/btf_types.go

@@ -0,0 +1,190 @@
+package btf
+
+import (
+	"encoding/binary"
+	"io"
+
+	"github.com/pkg/errors"
+)
+
+// btfKind describes a Type.
+type btfKind uint8
+
+// Equivalents of the BTF_KIND_* constants.
+const (
+	kindUnknown btfKind = iota
+	kindInt
+	kindPointer
+	kindArray
+	kindStruct
+	kindUnion
+	kindEnum
+	kindForward
+	kindTypedef
+	kindVolatile
+	kindConst
+	kindRestrict
+	// Added ~4.20
+	kindFunc
+	kindFuncProto
+	// Added ~5.1
+	kindVar
+	kindDatasec
+)
+
+const (
+	btfTypeKindShift = 24
+	btfTypeKindLen   = 4
+	btfTypeVlenShift = 0
+	btfTypeVlenMask  = 16
+)
+
+// btfType is equivalent to struct btf_type in Documentation/bpf/btf.rst.
+type btfType struct {
+	NameOff uint32
+	/* "info" bits arrangement
+	 * bits  0-15: vlen (e.g. # of struct's members)
+	 * bits 16-23: unused
+	 * bits 24-27: kind (e.g. int, ptr, array...etc)
+	 * bits 28-30: unused
+	 * bit     31: kind_flag, currently used by
+	 *             struct, union and fwd
+	 */
+	Info uint32
+	/* "size" is used by INT, ENUM, STRUCT and UNION.
+	 * "size" tells the size of the type it is describing.
+	 *
+	 * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
+	 * FUNC and FUNC_PROTO.
+	 * "type" is a type_id referring to another type.
+	 */
+	SizeType uint32
+}
+
+func mask(len uint32) uint32 {
+	return (1 << len) - 1
+}
+
+func (bt *btfType) info(len, shift uint32) uint32 {
+	return (bt.Info >> shift) & mask(len)
+}
+
+func (bt *btfType) setInfo(value, len, shift uint32) {
+	bt.Info &^= mask(len) << shift
+	bt.Info |= (value & mask(len)) << shift
+}
+
+func (bt *btfType) Kind() btfKind {
+	return btfKind(bt.info(btfTypeKindLen, btfTypeKindShift))
+}
+
+func (bt *btfType) SetKind(kind btfKind) {
+	bt.setInfo(uint32(kind), btfTypeKindLen, btfTypeKindShift)
+}
+
+func (bt *btfType) Vlen() int {
+	return int(bt.info(btfTypeVlenMask, btfTypeVlenShift))
+}
+
+func (bt *btfType) SetVlen(vlen int) {
+	bt.setInfo(uint32(vlen), btfTypeVlenMask, btfTypeVlenShift)
+}
+
+func (bt *btfType) Type() TypeID {
+	// TODO: Panic here if wrong kind?
+	return TypeID(bt.SizeType)
+}
+
+func (bt *btfType) Size() uint32 {
+	// TODO: Panic here if wrong kind?
+	return bt.SizeType
+}
+
+type rawType struct {
+	btfType
+	data interface{}
+}
+
+func (rt *rawType) Marshal(w io.Writer, bo binary.ByteOrder) error {
+	if err := binary.Write(w, bo, &rt.btfType); err != nil {
+		return err
+	}
+
+	if rt.data == nil {
+		return nil
+	}
+
+	return binary.Write(w, bo, rt.data)
+}
+
+type btfArray struct {
+	Type      TypeID
+	IndexType TypeID
+	Nelems    uint32
+}
+
+type btfMember struct {
+	NameOff uint32
+	Type    TypeID
+	Offset  uint32
+}
+
+func readTypes(r io.Reader, bo binary.ByteOrder) ([]rawType, error) {
+	var (
+		header btfType
+		types  []rawType
+	)
+
+	for id := TypeID(1); ; id++ {
+		if err := binary.Read(r, bo, &header); err == io.EOF {
+			return types, nil
+		} else if err != nil {
+			return nil, errors.Wrapf(err, "can't read type info for id %v", id)
+		}
+
+		var data interface{}
+		switch header.Kind() {
+		case kindInt:
+			// sizeof(uint32)
+			data = make([]byte, 4)
+		case kindPointer:
+		case kindArray:
+			data = new(btfArray)
+		case kindStruct:
+			fallthrough
+		case kindUnion:
+			data = make([]btfMember, header.Vlen())
+		case kindEnum:
+			// sizeof(struct btf_enum)
+			data = make([]byte, header.Vlen()*4*2)
+		case kindForward:
+		case kindTypedef:
+		case kindVolatile:
+		case kindConst:
+		case kindRestrict:
+		case kindFunc:
+		case kindFuncProto:
+			// sizeof(struct btf_param)
+			data = make([]byte, header.Vlen()*4*2)
+		case kindVar:
+			// sizeof(struct btf_variable)
+			data = make([]byte, 4)
+		case kindDatasec:
+			// sizeof(struct btf_var_secinfo)
+			data = make([]byte, header.Vlen()*4*3)
+		default:
+			return nil, errors.Errorf("type id %v: unknown kind: %v", id, header.Kind())
+		}
+
+		if data == nil {
+			types = append(types, rawType{header, nil})
+			continue
+		}
+
+		if err := binary.Read(r, bo, data); err != nil {
+			return nil, errors.Wrapf(err, "type id %d: kind %v: can't read %T", id, header.Kind(), data)
+		}
+
+		types = append(types, rawType{header, data})
+	}
+}

vendor/github.com/cilium/ebpf/internal/btf/doc.go

@@ -0,0 +1,8 @@
+// Package btf handles data encoded according to the BPF Type Format.
+//
+// The canonical documentation lives in the Linux kernel repository and is
+// available at https://www.kernel.org/doc/html/latest/bpf/btf.html
+//
+// The API is very much unstable. You should only use this via the main
+// ebpf library.
+package btf

vendor/github.com/cilium/ebpf/internal/btf/ext_info.go

@@ -0,0 +1,184 @@
+package btf
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+	"io/ioutil"
+
+	"github.com/cilium/ebpf/asm"
+	"github.com/cilium/ebpf/internal"
+
+	"github.com/pkg/errors"
+)
+
+type btfExtHeader struct {
+	Magic   uint16
+	Version uint8
+	Flags   uint8
+	HdrLen  uint32
+
+	FuncInfoOff uint32
+	FuncInfoLen uint32
+	LineInfoOff uint32
+	LineInfoLen uint32
+}
+
+func parseExtInfos(r io.ReadSeeker, bo binary.ByteOrder, strings stringTable) (funcInfo, lineInfo map[string]extInfo, err error) {
+	const expectedMagic = 0xeB9F
+
+	var header btfExtHeader
+	if err := binary.Read(r, bo, &header); err != nil {
+		return nil, nil, errors.Wrap(err, "can't read header")
+	}
+
+	if header.Magic != expectedMagic {
+		return nil, nil, errors.Errorf("incorrect magic value %v", header.Magic)
+	}
+
+	if header.Version != 1 {
+		return nil, nil, errors.Errorf("unexpected version %v", header.Version)
+	}
+
+	if header.Flags != 0 {
+		return nil, nil, errors.Errorf("unsupported flags %v", header.Flags)
+	}
+
+	remainder := int64(header.HdrLen) - int64(binary.Size(&header))
+	if remainder < 0 {
+		return nil, nil, errors.New("header is too short")
+	}
+
+	// Of course, the .BTF.ext header has different semantics than the
+	// .BTF ext header. We need to ignore non-null values.
+	_, err = io.CopyN(ioutil.Discard, r, remainder)
+	if err != nil {
+		return nil, nil, errors.Wrap(err, "header padding")
+	}
+
+	if _, err := r.Seek(int64(header.HdrLen+header.FuncInfoOff), io.SeekStart); err != nil {
+		return nil, nil, errors.Wrap(err, "can't seek to function info section")
+	}
+
+	funcInfo, err = parseExtInfo(io.LimitReader(r, int64(header.FuncInfoLen)), bo, strings)
+	if err != nil {
+		return nil, nil, errors.Wrap(err, "function info")
+	}
+
+	if _, err := r.Seek(int64(header.HdrLen+header.LineInfoOff), io.SeekStart); err != nil {
+		return nil, nil, errors.Wrap(err, "can't seek to line info section")
+	}
+
+	lineInfo, err = parseExtInfo(io.LimitReader(r, int64(header.LineInfoLen)), bo, strings)
+	if err != nil {
+		return nil, nil, errors.Wrap(err, "line info")
+	}
+
+	return funcInfo, lineInfo, nil
+}
+
+type btfExtInfoSec struct {
+	SecNameOff uint32
+	NumInfo    uint32
+}
+
+type extInfoRecord struct {
+	InsnOff uint64
+	Opaque  []byte
+}
+
+type extInfo struct {
+	recordSize uint32
+	records    []extInfoRecord
+}
+
+func (ei extInfo) append(other extInfo, offset uint64) (extInfo, error) {
+	if other.recordSize != ei.recordSize {
+		return extInfo{}, errors.Errorf("ext_info record size mismatch, want %d (got %d)", ei.recordSize, other.recordSize)
+	}
+
+	records := make([]extInfoRecord, 0, len(ei.records)+len(other.records))
+	records = append(records, ei.records...)
+	for _, info := range other.records {
+		records = append(records, extInfoRecord{
+			InsnOff: info.InsnOff + offset,
+			Opaque:  info.Opaque,
+		})
+	}
+	return extInfo{ei.recordSize, records}, nil
+}
+
+func (ei extInfo) MarshalBinary() ([]byte, error) {
+	if len(ei.records) == 0 {
+		return nil, nil
+	}
+
+	buf := bytes.NewBuffer(make([]byte, 0, int(ei.recordSize)*len(ei.records)))
+	for _, info := range ei.records {
+		// The kernel expects offsets in number of raw bpf instructions,
+		// while the ELF tracks it in bytes.
+		insnOff := uint32(info.InsnOff / asm.InstructionSize)
+		if err := binary.Write(buf, internal.NativeEndian, insnOff); err != nil {
+			return nil, errors.Wrap(err, "can't write instruction offset")
+		}
+
+		buf.Write(info.Opaque)
+	}
+
+	return buf.Bytes(), nil
+}
+
+func parseExtInfo(r io.Reader, bo binary.ByteOrder, strings stringTable) (map[string]extInfo, error) {
+	var recordSize uint32
+	if err := binary.Read(r, bo, &recordSize); err != nil {
+		return nil, errors.Wrap(err, "can't read record size")
+	}
+
+	if recordSize < 4 {
+		// Need at least insnOff
+		return nil, errors.New("record size too short")
+	}
+
+	result := make(map[string]extInfo)
+	for {
+		var infoHeader btfExtInfoSec
+		if err := binary.Read(r, bo, &infoHeader); err == io.EOF {
+			return result, nil
+		} else if err != nil {
+			return nil, errors.Wrap(err, "can't read ext info header")
+		}
+
+		secName, err := strings.Lookup(infoHeader.SecNameOff)
+		if err != nil {
+			return nil, errors.Wrap(err, "can't get section name")
+		}
+
+		if infoHeader.NumInfo == 0 {
+			return nil, errors.Errorf("section %s has invalid number of records", secName)
+		}
+
+		var records []extInfoRecord
+		for i := uint32(0); i < infoHeader.NumInfo; i++ {
+			var byteOff uint32
+			if err := binary.Read(r, bo, &byteOff); err != nil {
+				return nil, errors.Wrapf(err, "section %v: can't read extended info offset", secName)
+			}
+
+			buf := make([]byte, int(recordSize-4))
+			if _, err := io.ReadFull(r, buf); err != nil {
+				return nil, errors.Wrapf(err, "section %v: can't read record", secName)
+			}
+
+			if byteOff%asm.InstructionSize != 0 {
+				return nil, errors.Errorf("section %v: offset %v is not aligned with instruction size", secName, byteOff)
+			}
+
+			records = append(records, extInfoRecord{uint64(byteOff), buf})
+		}
+
+		result[secName] = extInfo{
+			recordSize,
+			records,
+		}
+	}
+}

vendor/github.com/cilium/ebpf/internal/btf/strings.go

@@ -0,0 +1,60 @@
+package btf
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+
+	"github.com/pkg/errors"
+)
+
+type stringTable []byte
+
+func readStringTable(r io.Reader) (stringTable, error) {
+	contents, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, errors.Wrap(err, "can't read string table")
+	}
+
+	if len(contents) < 1 {
+		return nil, errors.New("string table is empty")
+	}
+
+	if contents[0] != '\x00' {
+		return nil, errors.New("first item in string table is non-empty")
+	}
+
+	if contents[len(contents)-1] != '\x00' {
+		return nil, errors.New("string table isn't null terminated")
+	}
+
+	return stringTable(contents), nil
+}
+
+func (st stringTable) Lookup(offset uint32) (string, error) {
+	if int64(offset) > int64(^uint(0)>>1) {
+		return "", errors.Errorf("offset %d overflows int", offset)
+	}
+
+	pos := int(offset)
+	if pos >= len(st) {
+		return "", errors.Errorf("offset %d is out of bounds", offset)
+	}
+
+	if pos > 0 && st[pos-1] != '\x00' {
+		return "", errors.Errorf("offset %d isn't start of a string", offset)
+	}
+
+	str := st[pos:]
+	end := bytes.IndexByte(str, '\x00')
+	if end == -1 {
+		return "", errors.Errorf("offset %d isn't null terminated", offset)
+	}
+
+	return string(str[:end]), nil
+}
+
+func (st stringTable) LookupName(offset uint32) (Name, error) {
+	str, err := st.Lookup(offset)
+	return Name(str), err
+}

vendor/github.com/cilium/ebpf/internal/btf/types.go

@@ -0,0 +1,550 @@
+package btf
+
+import (
+	"math"
+
+	"github.com/pkg/errors"
+)
+
+const maxTypeDepth = 32
+
+// TypeID identifies a type in a BTF section.
+type TypeID uint32
+
+// ID implements part of the Type interface.
+func (tid TypeID) ID() TypeID {
+	return tid
+}
+
+// Type represents a type described by BTF.
+type Type interface {
+	ID() TypeID
+
+	// Make a copy of the type, without copying Type members.
+	copy() Type
+
+	walk(*copyStack)
+}
+
+// Name identifies a type.
+//
+// Anonymous types have an empty name.
+type Name string
+
+func (n Name) name() string {
+	return string(n)
+}
+
+// Void is the unit type of BTF.
+type Void struct{}
+
+func (v Void) ID() TypeID      { return 0 }
+func (v Void) copy() Type      { return Void{} }
+func (v Void) walk(*copyStack) {}
+
+// Int is an integer of a given length.
+type Int struct {
+	TypeID
+	Name
+
+	// The size of the integer in bytes.
+	Size uint32
+}
+
+func (i *Int) size() uint32    { return i.Size }
+func (i *Int) walk(*copyStack) {}
+func (i *Int) copy() Type {
+	cpy := *i
+	return &cpy
+}
+
+// Pointer is a pointer to another type.
+type Pointer struct {
+	TypeID
+	Target Type
+}
+
+func (p *Pointer) size() uint32       { return 8 }
+func (p *Pointer) walk(cs *copyStack) { cs.push(&p.Target) }
+func (p *Pointer) copy() Type {
+	cpy := *p
+	return &cpy
+}
+
+// Array is an array with a fixed number of elements.
+type Array struct {
+	TypeID
+	Type   Type
+	Nelems uint32
+}
+
+func (arr *Array) walk(cs *copyStack) { cs.push(&arr.Type) }
+func (arr *Array) copy() Type {
+	cpy := *arr
+	return &cpy
+}
+
+// Struct is a compound type of consecutive members.
+type Struct struct {
+	TypeID
+	Name
+	// The size of the struct including padding, in bytes
+	Size    uint32
+	Members []Member
+}
+
+func (s *Struct) size() uint32 { return s.Size }
+
+func (s *Struct) walk(cs *copyStack) {
+	for i := range s.Members {
+		cs.push(&s.Members[i].Type)
+	}
+}
+
+func (s *Struct) copy() Type {
+	cpy := *s
+	cpy.Members = copyMembers(cpy.Members)
+	return &cpy
+}
+
+// Union is a compound type where members occupy the same memory.
+type Union struct {
+	TypeID
+	Name
+	// The size of the union including padding, in bytes.
+	Size    uint32
+	Members []Member
+}
+
+func (u *Union) size() uint32 { return u.Size }
+
+func (u *Union) walk(cs *copyStack) {
+	for i := range u.Members {
+		cs.push(&u.Members[i].Type)
+	}
+}
+
+func (u *Union) copy() Type {
+	cpy := *u
+	cpy.Members = copyMembers(cpy.Members)
+	return &cpy
+}
+
+// Member is part of a Struct or Union.
+//
+// It is not a valid Type.
+type Member struct {
+	Name
+	Type   Type
+	Offset uint32
+}
+
+func copyMembers(in []Member) []Member {
+	cpy := make([]Member, 0, len(in))
+	for _, member := range in {
+		cpy = append(cpy, member)
+	}
+	return cpy
+}
+
+// Enum lists possible values.
+type Enum struct {
+	TypeID
+	Name
+}
+
+func (e *Enum) size() uint32    { return 4 }
+func (e *Enum) walk(*copyStack) {}
+func (e *Enum) copy() Type {
+	cpy := *e
+	return &cpy
+}
+
+// Fwd is a forward declaration of a Type.
+type Fwd struct {
+	TypeID
+	Name
+}
+
+func (f *Fwd) walk(*copyStack) {}
+func (f *Fwd) copy() Type {
+	cpy := *f
+	return &cpy
+}
+
+// Typedef is an alias of a Type.
+type Typedef struct {
+	TypeID
+	Name
+	Type Type
+}
+
+func (td *Typedef) walk(cs *copyStack) { cs.push(&td.Type) }
+func (td *Typedef) copy() Type {
+	cpy := *td
+	return &cpy
+}
+
+// Volatile is a modifier.
+type Volatile struct {
+	TypeID
+	Type Type
+}
+
+func (v *Volatile) walk(cs *copyStack) { cs.push(&v.Type) }
+func (v *Volatile) copy() Type {
+	cpy := *v
+	return &cpy
+}
+
+// Const is a modifier.
+type Const struct {
+	TypeID
+	Type Type
+}
+
+func (c *Const) walk(cs *copyStack) { cs.push(&c.Type) }
+func (c *Const) copy() Type {
+	cpy := *c
+	return &cpy
+}
+
+// Restrict is a modifier.
+type Restrict struct {
+	TypeID
+	Type Type
+}
+
+func (r *Restrict) walk(cs *copyStack) { cs.push(&r.Type) }
+func (r *Restrict) copy() Type {
+	cpy := *r
+	return &cpy
+}
+
+// Func is a function definition.
+type Func struct {
+	TypeID
+	Name
+	Type Type
+}
+
+func (f *Func) walk(cs *copyStack) { cs.push(&f.Type) }
+func (f *Func) copy() Type {
+	cpy := *f
+	return &cpy
+}
+
+// FuncProto is a function declaration.
+type FuncProto struct {
+	TypeID
+	Return Type
+	// Parameters not supported yet
+}
+
+func (fp *FuncProto) walk(cs *copyStack) { cs.push(&fp.Return) }
+func (fp *FuncProto) copy() Type {
+	cpy := *fp
+	return &cpy
+}
+
+// Var is a global variable.
+type Var struct {
+	TypeID
+	Name
+	Type Type
+}
+
+func (v *Var) walk(cs *copyStack) { cs.push(&v.Type) }
+func (v *Var) copy() Type {
+	cpy := *v
+	return &cpy
+}
+
+// Datasec is a global program section containing data.
+type Datasec struct {
+	TypeID
+	Name
+	Size uint32
+}
+
+func (ds *Datasec) size() uint32    { return ds.Size }
+func (ds *Datasec) walk(*copyStack) {}
+func (ds *Datasec) copy() Type {
+	cpy := *ds
+	return &cpy
+}
+
+type sizer interface {
+	size() uint32
+}
+
+var (
+	_ sizer = (*Int)(nil)
+	_ sizer = (*Pointer)(nil)
+	_ sizer = (*Struct)(nil)
+	_ sizer = (*Union)(nil)
+	_ sizer = (*Enum)(nil)
+	_ sizer = (*Datasec)(nil)
+)
+
+// Sizeof returns the size of a type in bytes.
+//
+// Returns an error if the size can't be computed.
+func Sizeof(typ Type) (int, error) {
+	var (
+		n    = int64(1)
+		elem int64
+	)
+
+	for i := 0; i < maxTypeDepth; i++ {
+		switch v := typ.(type) {
+		case *Array:
+			if n > 0 && int64(v.Nelems) > math.MaxInt64/n {
+				return 0, errors.New("overflow")
+			}
+
+			// Arrays may be of zero length, which allows
+			// n to be zero as well.
+			n *= int64(v.Nelems)
+			typ = v.Type
+			continue
+
+		case sizer:
+			elem = int64(v.size())
+
+		case *Typedef:
+			typ = v.Type
+			continue
+		case *Volatile:
+			typ = v.Type
+			continue
+		case *Const:
+			typ = v.Type
+			continue
+		case *Restrict:
+			typ = v.Type
+			continue
+
+		default:
+			return 0, errors.Errorf("unrecognized type %T", typ)
+		}
+
+		if n > 0 && elem > math.MaxInt64/n {
+			return 0, errors.New("overflow")
+		}
+
+		size := n * elem
+		if int64(int(size)) != size {
+			return 0, errors.New("overflow")
+		}
+
+		return int(size), nil
+	}
+
+	return 0, errors.New("exceeded type depth")
+}
+
+// copy a Type recursively.
+//
+// typ may form a cycle.
+func copyType(typ Type) Type {
+	var (
+		copies = make(map[Type]Type)
+		work   copyStack
+	)
+
+	for t := &typ; t != nil; t = work.pop() {
+		// *t is the identity of the type.
+		if cpy := copies[*t]; cpy != nil {
+			*t = cpy
+			continue
+		}
+
+		cpy := (*t).copy()
+		copies[*t] = cpy
+		*t = cpy
+
+		// Mark any nested types for copying.
+		cpy.walk(&work)
+	}
+
+	return typ
+}
+
+// copyStack keeps track of pointers to types which still
+// need to be copied.
+type copyStack []*Type
+
+// push adds a type to the stack.
+func (cs *copyStack) push(t *Type) {
+	*cs = append(*cs, t)
+}
+
+// pop returns the topmost Type, or nil.
+func (cs *copyStack) pop() *Type {
+	n := len(*cs)
+	if n == 0 {
+		return nil
+	}
+
+	t := (*cs)[n-1]
+	*cs = (*cs)[:n-1]
+	return t
+}
+
+type namer interface {
+	name() string
+}
+
+var _ namer = Name("")
+
+// inflateRawTypes takes a list of raw btf types linked via type IDs, and turns
+// it into a graph of Types connected via pointers.
+//
+// Returns a map of named types (so, where NameOff is non-zero). Since BTF ignores
+// compilation units, multiple types may share the same name. A Type may form a
+// cyclic graph by pointing at itself.
+func inflateRawTypes(rawTypes []rawType, rawStrings stringTable) (namedTypes map[string][]Type, err error) {
+	type fixup struct {
+		id  TypeID
+		typ *Type
+	}
+
+	var fixups []fixup
+	convertMembers := func(raw []btfMember) ([]Member, error) {
+		// NB: The fixup below relies on pre-allocating this array to
+		// work, since otherwise append might re-allocate members.
+		members := make([]Member, 0, len(raw))
+		for i, btfMember := range raw {
+			name, err := rawStrings.LookupName(btfMember.NameOff)
+			if err != nil {
+				return nil, errors.Wrapf(err, "can't get name for member %d", i)
+			}
+			members = append(members, Member{
+				Name:   name,
+				Offset: btfMember.Offset,
+			})
+		}
+		for i := range members {
+			fixups = append(fixups, fixup{raw[i].Type, &members[i].Type})
+		}
+		return members, nil
+	}
+
+	types := make([]Type, 0, len(rawTypes))
+	types = append(types, Void{})
+	namedTypes = make(map[string][]Type)
+
+	for i, raw := range rawTypes {
+		var (
+			// Void is defined to always be type ID 0, and is thus
+			// omitted from BTF.
+			id  = TypeID(i + 1)
+			typ Type
+		)
+
+		name, err := rawStrings.LookupName(raw.NameOff)
+		if err != nil {
+			return nil, errors.Wrapf(err, "can't get name for type id %d", id)
+		}
+
+		switch raw.Kind() {
+		case kindInt:
+			typ = &Int{id, name, raw.Size()}
+
+		case kindPointer:
+			ptr := &Pointer{id, nil}
+			fixups = append(fixups, fixup{raw.Type(), &ptr.Target})
+			typ = ptr
+
+		case kindArray:
+			btfArr := raw.data.(*btfArray)
+
+			// IndexType is unused according to btf.rst.
+			// Don't make it available right now.
+			arr := &Array{id, nil, btfArr.Nelems}
+			fixups = append(fixups, fixup{btfArr.Type, &arr.Type})
+			typ = arr
+
+		case kindStruct:
+			members, err := convertMembers(raw.data.([]btfMember))
+			if err != nil {
+				return nil, errors.Wrapf(err, "struct %s (id %d)", name, id)
+			}
+			typ = &Struct{id, name, raw.Size(), members}
+
+		case kindUnion:
+			members, err := convertMembers(raw.data.([]btfMember))
+			if err != nil {
+				return nil, errors.Wrapf(err, "union %s (id %d)", name, id)
+			}
+			typ = &Union{id, name, raw.Size(), members}
+
+		case kindEnum:
+			typ = &Enum{id, name}
+
+		case kindForward:
+			typ = &Fwd{id, name}
+
+		case kindTypedef:
+			typedef := &Typedef{id, name, nil}
+			fixups = append(fixups, fixup{raw.Type(), &typedef.Type})
+			typ = typedef
+
+		case kindVolatile:
+			volatile := &Volatile{id, nil}
+			fixups = append(fixups, fixup{raw.Type(), &volatile.Type})
+			typ = volatile
+
+		case kindConst:
+			cnst := &Const{id, nil}
+			fixups = append(fixups, fixup{raw.Type(), &cnst.Type})
+			typ = cnst
+
+		case kindRestrict:
+			restrict := &Restrict{id, nil}
+			fixups = append(fixups, fixup{raw.Type(), &restrict.Type})
+			typ = restrict
+
+		case kindFunc:
+			fn := &Func{id, name, nil}
+			fixups = append(fixups, fixup{raw.Type(), &fn.Type})
+			typ = fn
+
+		case kindFuncProto:
+			fp := &FuncProto{id, nil}
+			fixups = append(fixups, fixup{raw.Type(), &fp.Return})
+			typ = fp
+
+		case kindVar:
+			v := &Var{id, name, nil}
+			fixups = append(fixups, fixup{raw.Type(), &v.Type})
+			typ = v
+
+		case kindDatasec:
+			typ = &Datasec{id, name, raw.SizeType}
+
+		default:
+			return nil, errors.Errorf("type id %d: unknown kind: %v", id, raw.Kind())
+		}
+
+		types = append(types, typ)
+
+		if namer, ok := typ.(namer); ok {
+			if name := namer.name(); name != "" {
+				namedTypes[name] = append(namedTypes[name], typ)
+			}
+		}
+	}
+
+	for _, fixup := range fixups {
+		i := int(fixup.id)
+		if i >= len(types) {
+			return nil, errors.Errorf("reference to invalid type id: %d", fixup.id)
+		}
+
+		*fixup.typ = types[i]
+	}
+
+	return namedTypes, nil
+}

vendor/github.com/cilium/ebpf/internal/errors.go

@@ -0,0 +1,50 @@
+package internal
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+
+	"github.com/cilium/ebpf/internal/unix"
+	"github.com/pkg/errors"
+)
+
+// ErrorWithLog returns an error that includes logs from the
+// kernel verifier.
+//
+// logErr should be the error returned by the syscall that generated
+// the log. It is used to check for truncation of the output.
+func ErrorWithLog(err error, log []byte, logErr error) error {
+	logStr := strings.Trim(CString(log), "\t\r\n ")
+	if errors.Cause(logErr) == unix.ENOSPC {
+		logStr += " (truncated...)"
+	}
+
+	return &loadError{err, logStr}
+}
+
+type loadError struct {
+	cause error
+	log   string
+}
+
+func (le *loadError) Error() string {
+	if le.log == "" {
+		return le.cause.Error()
+	}
+
+	return fmt.Sprintf("%s: %s", le.cause, le.log)
+}
+
+func (le *loadError) Cause() error {
+	return le.cause
+}
+
+// CString turns a NUL / zero terminated byte buffer into a string.
+func CString(in []byte) string {
+	inLen := bytes.IndexByte(in, 0)
+	if inLen == -1 {
+		return ""
+	}
+	return string(in[:inLen])
+}

vendor/github.com/cilium/ebpf/internal/fd.go

@@ -0,0 +1,63 @@
+package internal
+
+import (
+	"runtime"
+	"strconv"
+
+	"github.com/cilium/ebpf/internal/unix"
+
+	"github.com/pkg/errors"
+)
+
+var ErrClosedFd = errors.New("use of closed file descriptor")
+
+type FD struct {
+	raw int64
+}
+
+func NewFD(value uint32) *FD {
+	fd := &FD{int64(value)}
+	runtime.SetFinalizer(fd, (*FD).Close)
+	return fd
+}
+
+func (fd *FD) String() string {
+	return strconv.FormatInt(fd.raw, 10)
+}
+
+func (fd *FD) Value() (uint32, error) {
+	if fd.raw < 0 {
+		return 0, ErrClosedFd
+	}
+
+	return uint32(fd.raw), nil
+}
+
+func (fd *FD) Close() error {
+	if fd.raw < 0 {
+		return nil
+	}
+
+	value := int(fd.raw)
+	fd.raw = -1
+
+	fd.Forget()
+	return unix.Close(value)
+}
+
+func (fd *FD) Forget() {
+	runtime.SetFinalizer(fd, nil)
+}
+
+func (fd *FD) Dup() (*FD, error) {
+	if fd.raw < 0 {
+		return nil, ErrClosedFd
+	}
+
+	dup, err := unix.FcntlInt(uintptr(fd.raw), unix.F_DUPFD_CLOEXEC, 0)
+	if err != nil {
+		return nil, errors.Wrap(err, "can't dup fd")
+	}
+
+	return NewFD(uint32(dup)), nil
+}

vendor/github.com/cilium/ebpf/internal/io.go

@@ -0,0 +1,16 @@
+package internal
+
+import "github.com/pkg/errors"
+
+// DiscardZeroes makes sure that all written bytes are zero
+// before discarding them.
+type DiscardZeroes struct{}
+
+func (DiscardZeroes) Write(p []byte) (int, error) {
+	for _, b := range p {
+		if b != 0 {
+			return 0, errors.New("encountered non-zero byte")
+		}
+	}
+	return len(p), nil
+}

vendor/github.com/cilium/ebpf/internal/ptr.go

@@ -0,0 +1,26 @@
+package internal
+
+import "unsafe"
+
+// NewPointer creates a 64-bit pointer from an unsafe Pointer.
+func NewPointer(ptr unsafe.Pointer) Pointer {
+	return Pointer{ptr: ptr}
+}
+
+// NewSlicePointer creates a 64-bit pointer from a byte slice.
+func NewSlicePointer(buf []byte) Pointer {
+	if len(buf) == 0 {
+		return Pointer{}
+	}
+
+	return Pointer{ptr: unsafe.Pointer(&buf[0])}
+}
+
+// NewStringPointer creates a 64-bit pointer from a string.
+func NewStringPointer(str string) Pointer {
+	if str == "" {
+		return Pointer{}
+	}
+
+	return Pointer{ptr: unsafe.Pointer(&[]byte(str)[0])}
+}

vendor/github.com/cilium/ebpf/internal/ptr_32_be.go

@@ -0,0 +1,14 @@
+// +build armbe mips mips64p32
+
+package internal
+
+import (
+	"unsafe"
+)
+
+// Pointer wraps an unsafe.Pointer to be 64bit to
+// conform to the syscall specification.
+type Pointer struct {
+	pad uint32
+	ptr unsafe.Pointer
+}

vendor/github.com/cilium/ebpf/internal/ptr_32_le.go

@@ -0,0 +1,14 @@
+// +build 386 amd64p32 arm mipsle mips64p32le
+
+package internal
+
+import (
+	"unsafe"
+)
+
+// Pointer wraps an unsafe.Pointer to be 64bit to
+// conform to the syscall specification.
+type Pointer struct {
+	ptr unsafe.Pointer
+	pad uint32
+}

vendor/github.com/cilium/ebpf/internal/ptr_64.go

@@ -0,0 +1,14 @@
+// +build !386,!amd64p32,!arm,!mipsle,!mips64p32le
+// +build !armbe,!mips,!mips64p32
+
+package internal
+
+import (
+	"unsafe"
+)
+
+// Pointer wraps an unsafe.Pointer to be 64bit to
+// conform to the syscall specification.
+type Pointer struct {
+	ptr unsafe.Pointer
+}

vendor/github.com/cilium/ebpf/internal/syscall.go

@@ -0,0 +1,23 @@
+package internal
+
+import (
+	"runtime"
+	"unsafe"
+
+	"github.com/cilium/ebpf/internal/unix"
+)
+
+// BPF wraps SYS_BPF.
+//
+// Any pointers contained in attr must use the Pointer type from this package.
+func BPF(cmd int, attr unsafe.Pointer, size uintptr) (uintptr, error) {
+	r1, _, errNo := unix.Syscall(unix.SYS_BPF, uintptr(cmd), uintptr(attr), size)
+	runtime.KeepAlive(attr)
+
+	var err error
+	if errNo != 0 {
+		err = errNo
+	}
+
+	return r1, err
+}