[feature] Inherit resource limits from cgroups (#1336)

When GTS is running in a container runtime which has configured CPU or
memory limits or under an init system that uses cgroups to impose CPU
and memory limits the values the Go runtime sees for GOMAXPROCS and
GOMEMLIMIT are still based on the host resources, not the cgroup.

At least for the throttling middlewares which use GOMAXPROCS to
configure their queue size, this can result in GTS running with values
too big compared to the resources that will actuall be available to it.

This introduces 2 dependencies which can pick up resource contraints
from the current cgroup and tune the Go runtime accordingly. This should
result in the different queues being appropriately sized and in general
more predictable performance. These dependencies are a no-op on
non-Linux systems or if running in a cgroup that doesn't set a limit on
CPU or memory.

The automatic tuning of GOMEMLIMIT can be disabled by either explicitly
setting GOMEMLIMIT yourself or by setting AUTOMEMLIMIT=off. The
automatic tuning of GOMAXPROCS can similarly be counteracted by setting
GOMAXPROCS yourself.

8 files changed, 2717 insertions, 0 deletions

diff --git a/vendor/github.com/cilium/ebpf/internal/btf/btf.go b/vendor/github.com/cilium/ebpf/internal/btf/btf.go
new file mode 100644
index 000000000..1e66d9476
--- /dev/null
+++ b/vendor/github.com/cilium/ebpf/internal/btf/btf.go
@@ -0,0 +1,791 @@
+package btf
+
+import (
+	"bytes"
+	"debug/elf"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"math"
+	"os"
+	"reflect"
+	"sync"
+	"unsafe"
+
+	"github.com/cilium/ebpf/internal"
+	"github.com/cilium/ebpf/internal/unix"
+)
+
+const btfMagic = 0xeB9F
+
+// Errors returned by BTF functions.
+var (
+	ErrNotSupported   = internal.ErrNotSupported
+	ErrNotFound       = errors.New("not found")
+	ErrNoExtendedInfo = errors.New("no extended info")
+)
+
+// Spec represents decoded BTF.
+type Spec struct {
+	rawTypes   []rawType
+	strings    stringTable
+	types      []Type
+	namedTypes map[string][]namedType
+	funcInfos  map[string]extInfo
+	lineInfos  map[string]extInfo
+	coreRelos  map[string]bpfCoreRelos
+	byteOrder  binary.ByteOrder
+}
+
+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 := internal.NewSafeELFFile(rd)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	btfSection, btfExtSection, sectionSizes, err := findBtfSections(file)
+	if err != nil {
+		return nil, err
+	}
+
+	if btfSection == nil {
+		return nil, nil
+	}
+
+	symbols, err := file.Symbols()
+	if err != nil {
+		return nil, fmt.Errorf("can't read symbols: %v", err)
+	}
+
+	variableOffsets := make(map[variable]uint32)
+	for _, symbol := range symbols {
+		if idx := symbol.Section; idx >= elf.SHN_LORESERVE && idx <= elf.SHN_HIRESERVE {
+			// Ignore things like SHN_ABS
+			continue
+		}
+
+		if int(symbol.Section) >= len(file.Sections) {
+			return nil, fmt.Errorf("symbol %s: invalid section %d", symbol.Name, symbol.Section)
+		}
+
+		secName := file.Sections[symbol.Section].Name
+		if _, ok := sectionSizes[secName]; !ok {
+			continue
+		}
+
+		if symbol.Value > math.MaxUint32 {
+			return nil, fmt.Errorf("section %s: symbol %s: size exceeds maximum", secName, symbol.Name)
+		}
+
+		variableOffsets[variable{secName, symbol.Name}] = uint32(symbol.Value)
+	}
+
+	spec, err := loadNakedSpec(btfSection.Open(), file.ByteOrder, sectionSizes, variableOffsets)
+	if err != nil {
+		return nil, err
+	}
+
+	if btfExtSection == nil {
+		return spec, nil
+	}
+
+	spec.funcInfos, spec.lineInfos, spec.coreRelos, err = parseExtInfos(btfExtSection.Open(), file.ByteOrder, spec.strings)
+	if err != nil {
+		return nil, fmt.Errorf("can't read ext info: %w", err)
+	}
+
+	return spec, nil
+}
+
+func findBtfSections(file *internal.SafeELFFile) (*elf.Section, *elf.Section, map[string]uint32, error) {
+	var (
+		btfSection    *elf.Section
+		btfExtSection *elf.Section
+		sectionSizes  = make(map[string]uint32)
+	)
+
+	for _, sec := range file.Sections {
+		switch sec.Name {
+		case ".BTF":
+			btfSection = sec
+		case ".BTF.ext":
+			btfExtSection = sec
+		default:
+			if sec.Type != elf.SHT_PROGBITS && sec.Type != elf.SHT_NOBITS {
+				break
+			}
+
+			if sec.Size > math.MaxUint32 {
+				return nil, nil, nil, fmt.Errorf("section %s exceeds maximum size", sec.Name)
+			}
+
+			sectionSizes[sec.Name] = uint32(sec.Size)
+		}
+	}
+	return btfSection, btfExtSection, sectionSizes, nil
+}
+
+func loadSpecFromVmlinux(rd io.ReaderAt) (*Spec, error) {
+	file, err := internal.NewSafeELFFile(rd)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	btfSection, _, _, err := findBtfSections(file)
+	if err != nil {
+		return nil, fmt.Errorf(".BTF ELF section: %s", err)
+	}
+	if btfSection == nil {
+		return nil, fmt.Errorf("unable to find .BTF ELF section")
+	}
+	return loadNakedSpec(btfSection.Open(), file.ByteOrder, nil, nil)
+}
+
+func loadNakedSpec(btf io.ReadSeeker, bo binary.ByteOrder, sectionSizes map[string]uint32, variableOffsets map[variable]uint32) (*Spec, error) {
+	rawTypes, rawStrings, err := parseBTF(btf, bo)
+	if err != nil {
+		return nil, err
+	}
+
+	err = fixupDatasec(rawTypes, rawStrings, sectionSizes, variableOffsets)
+	if err != nil {
+		return nil, err
+	}
+
+	types, typesByName, err := inflateRawTypes(rawTypes, rawStrings)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Spec{
+		rawTypes:   rawTypes,
+		namedTypes: typesByName,
+		types:      types,
+		strings:    rawStrings,
+		byteOrder:  bo,
+	}, nil
+}
+
+var kernelBTF struct {
+	sync.Mutex
+	*Spec
+}
+
+// LoadKernelSpec returns the current kernel's BTF information.
+//
+// Requires a >= 5.5 kernel with CONFIG_DEBUG_INFO_BTF enabled. Returns
+// ErrNotSupported if BTF is not enabled.
+func LoadKernelSpec() (*Spec, error) {
+	kernelBTF.Lock()
+	defer kernelBTF.Unlock()
+
+	if kernelBTF.Spec != nil {
+		return kernelBTF.Spec, nil
+	}
+
+	var err error
+	kernelBTF.Spec, err = loadKernelSpec()
+	return kernelBTF.Spec, err
+}
+
+func loadKernelSpec() (*Spec, error) {
+	release, err := unix.KernelRelease()
+	if err != nil {
+		return nil, fmt.Errorf("can't read kernel release number: %w", err)
+	}
+
+	fh, err := os.Open("/sys/kernel/btf/vmlinux")
+	if err == nil {
+		defer fh.Close()
+
+		return loadNakedSpec(fh, internal.NativeEndian, nil, nil)
+	}
+
+	// use same list of locations as libbpf
+	// https://github.com/libbpf/libbpf/blob/9a3a42608dbe3731256a5682a125ac1e23bced8f/src/btf.c#L3114-L3122
+	locations := []string{
+		"/boot/vmlinux-%s",
+		"/lib/modules/%s/vmlinux-%[1]s",
+		"/lib/modules/%s/build/vmlinux",
+		"/usr/lib/modules/%s/kernel/vmlinux",
+		"/usr/lib/debug/boot/vmlinux-%s",
+		"/usr/lib/debug/boot/vmlinux-%s.debug",
+		"/usr/lib/debug/lib/modules/%s/vmlinux",
+	}
+
+	for _, loc := range locations {
+		path := fmt.Sprintf(loc, release)
+
+		fh, err := os.Open(path)
+		if err != nil {
+			continue
+		}
+		defer fh.Close()
+
+		return loadSpecFromVmlinux(fh)
+	}
+
+	return nil, fmt.Errorf("no BTF for kernel version %s: %w", release, internal.ErrNotSupported)
+}
+
+func parseBTF(btf io.ReadSeeker, bo binary.ByteOrder) ([]rawType, stringTable, error) {
+	rawBTF, err := ioutil.ReadAll(btf)
+	if err != nil {
+		return nil, nil, fmt.Errorf("can't read BTF: %v", err)
+	}
+
+	rd := bytes.NewReader(rawBTF)
+
+	var header btfHeader
+	if err := binary.Read(rd, bo, &header); err != nil {
+		return nil, nil, fmt.Errorf("can't read header: %v", err)
+	}
+
+	if header.Magic != btfMagic {
+		return nil, nil, fmt.Errorf("incorrect magic value %v", header.Magic)
+	}
+
+	if header.Version != 1 {
+		return nil, nil, fmt.Errorf("unexpected version %v", header.Version)
+	}
+
+	if header.Flags != 0 {
+		return nil, nil, fmt.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")
+	}
+
+	if _, err := io.CopyN(internal.DiscardZeroes{}, rd, remainder); err != nil {
+		return nil, nil, fmt.Errorf("header padding: %v", err)
+	}
+
+	if _, err := rd.Seek(int64(header.HdrLen+header.StringOff), io.SeekStart); err != nil {
+		return nil, nil, fmt.Errorf("can't seek to start of string section: %v", err)
+	}
+
+	rawStrings, err := readStringTable(io.LimitReader(rd, int64(header.StringLen)))
+	if err != nil {
+		return nil, nil, fmt.Errorf("can't read type names: %w", err)
+	}
+
+	if _, err := rd.Seek(int64(header.HdrLen+header.TypeOff), io.SeekStart); err != nil {
+		return nil, nil, fmt.Errorf("can't seek to start of type section: %v", err)
+	}
+
+	rawTypes, err := readTypes(io.LimitReader(rd, int64(header.TypeLen)), bo)
+	if err != nil {
+		return nil, nil, fmt.Errorf("can't read types: %w", err)
+	}
+
+	return rawTypes, rawStrings, nil
+}
+
+type variable struct {
+	section string
+	name    string
+}
+
+func fixupDatasec(rawTypes []rawType, rawStrings stringTable, sectionSizes map[string]uint32, variableOffsets map[variable]uint32) error {
+	for i, rawType := range rawTypes {
+		if rawType.Kind() != kindDatasec {
+			continue
+		}
+
+		name, err := rawStrings.Lookup(rawType.NameOff)
+		if err != nil {
+			return err
+		}
+
+		if name == ".kconfig" || name == ".ksyms" {
+			return fmt.Errorf("reference to %s: %w", name, ErrNotSupported)
+		}
+
+		if rawTypes[i].SizeType != 0 {
+			continue
+		}
+
+		size, ok := sectionSizes[name]
+		if !ok {
+			return fmt.Errorf("data section %s: missing size", name)
+		}
+
+		rawTypes[i].SizeType = size
+
+		secinfos := rawType.data.([]btfVarSecinfo)
+		for j, secInfo := range secinfos {
+			id := int(secInfo.Type - 1)
+			if id >= len(rawTypes) {
+				return fmt.Errorf("data section %s: invalid type id %d for variable %d", name, id, j)
+			}
+
+			varName, err := rawStrings.Lookup(rawTypes[id].NameOff)
+			if err != nil {
+				return fmt.Errorf("data section %s: can't get name for type %d: %w", name, id, err)
+			}
+
+			offset, ok := variableOffsets[variable{name, varName}]
+			if !ok {
+				return fmt.Errorf("data section %s: missing offset for variable %s", name, varName)
+			}
+
+			secinfos[j].Offset = offset
+		}
+	}
+
+	return nil
+}
+
+type marshalOpts struct {
+	ByteOrder        binary.ByteOrder
+	StripFuncLinkage bool
+}
+
+func (s *Spec) marshal(opts marshalOpts) ([]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 _, raw := range s.rawTypes {
+		switch {
+		case opts.StripFuncLinkage && raw.Kind() == kindFunc:
+			raw.SetLinkage(linkageStatic)
+		}
+
+		if err := raw.Marshal(&buf, opts.ByteOrder); err != nil {
+			return nil, fmt.Errorf("can't marshal BTF: %w", err)
+		}
+	}
+
+	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]), opts.ByteOrder, header)
+	if err != nil {
+		return nil, fmt.Errorf("can't write header: %v", err)
+	}
+
+	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 which may wrap ErrNoExtendedInfo if the Spec doesn't
+// contain extended BTF info.
+func (s *Spec) Program(name string, length uint64) (*Program, error) {
+	if length == 0 {
+		return nil, errors.New("length musn't be zero")
+	}
+
+	if s.funcInfos == nil && s.lineInfos == nil && s.coreRelos == nil {
+		return nil, fmt.Errorf("BTF for section %s: %w", name, ErrNoExtendedInfo)
+	}
+
+	funcInfos, funcOK := s.funcInfos[name]
+	lineInfos, lineOK := s.lineInfos[name]
+	coreRelos, coreOK := s.coreRelos[name]
+
+	if !funcOK && !lineOK && !coreOK {
+		return nil, fmt.Errorf("no extended BTF info for section %s", name)
+	}
+
+	return &Program{s, length, funcInfos, lineInfos, coreRelos}, nil
+}
+
+// Datasec returns the BTF required to create maps which represent data sections.
+func (s *Spec) Datasec(name string) (*Map, error) {
+	var datasec Datasec
+	if err := s.FindType(name, &datasec); err != nil {
+		return nil, fmt.Errorf("data section %s: can't get BTF: %w", name, err)
+	}
+
+	m := NewMap(s, &Void{}, &datasec)
+	return &m, nil
+}
+
+// FindType searches for a type with a specific name.
+//
+// hint determines the type of the returned Type.
+//
+// Returns an error wrapping ErrNotFound if no matching
+// type exists in spec.
+func (s *Spec) FindType(name string, typ Type) error {
+	var (
+		wanted    = reflect.TypeOf(typ)
+		candidate Type
+	)
+
+	for _, typ := range s.namedTypes[essentialName(name)] {
+		if reflect.TypeOf(typ) != wanted {
+			continue
+		}
+
+		// Match against the full name, not just the essential one.
+		if typ.name() != name {
+			continue
+		}
+
+		if candidate != nil {
+			return fmt.Errorf("type %s: multiple candidates for %T", name, typ)
+		}
+
+		candidate = typ
+	}
+
+	if candidate == nil {
+		return fmt.Errorf("type %s: %w", name, ErrNotFound)
+	}
+
+	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 ErrNotSupported if BTF is not supported.
+func NewHandle(spec *Spec) (*Handle, error) {
+	if err := haveBTF(); err != nil {
+		return nil, err
+	}
+
+	if spec.byteOrder != internal.NativeEndian {
+		return nil, fmt.Errorf("can't load %s BTF on %s", spec.byteOrder, internal.NativeEndian)
+	}
+
+	btf, err := spec.marshal(marshalOpts{
+		ByteOrder:        internal.NativeEndian,
+		StripFuncLinkage: haveFuncLinkage() != nil,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("can't marshal BTF: %w", err)
+	}
+
+	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 {
+	spec       *Spec
+	key, value Type
+}
+
+// NewMap returns a new Map containing the given values.
+// The key and value arguments are initialized to Void if nil values are given.
+func NewMap(spec *Spec, key Type, value Type) Map {
+	if key == nil {
+		key = &Void{}
+	}
+	if value == nil {
+		value = &Void{}
+	}
+
+	return Map{
+		spec:  spec,
+		key:   key,
+		value: value,
+	}
+}
+
+// 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
+}
+
+// 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
+	coreRelos            bpfCoreRelos
+}
+
+// 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 fmt.Errorf("func infos: %w", err)
+	}
+
+	lineInfos, err := s.lineInfos.append(other.lineInfos, s.length)
+	if err != nil {
+		return fmt.Errorf("line infos: %w", err)
+	}
+
+	s.funcInfos = funcInfos
+	s.lineInfos = lineInfos
+	s.coreRelos = s.coreRelos.append(other.coreRelos, s.length)
+	s.length += other.length
+	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
+}
+
+// ProgramRelocations returns the CO-RE relocations required to adjust the
+// program to the target.
+//
+// This is a free function instead of a method to hide it from users
+// of package ebpf.
+func ProgramRelocations(s *Program, target *Spec) (map[uint64]Relocation, error) {
+	if len(s.coreRelos) == 0 {
+		return nil, nil
+	}
+
+	return coreRelocate(s.spec, target, s.coreRelos)
+}
+
+type bpfLoadBTFAttr struct {
+	btf         internal.Pointer
+	logBuf      internal.Pointer
+	btfSize     uint32
+	btfLogSize  uint32
+	btfLogLevel uint32
+}
+
+func bpfLoadBTF(attr *bpfLoadBTFAttr) (*internal.FD, error) {
+	fd, err := internal.BPF(internal.BPF_BTF_LOAD, unsafe.Pointer(attr), unsafe.Sizeof(*attr))
+	if err != nil {
+		return nil, err
+	}
+
+	return internal.NewFD(uint32(fd)), nil
+}
+
+func marshalBTF(types interface{}, strings []byte, bo binary.ByteOrder) []byte {
+	const minHeaderLength = 24
+
+	typesLen := uint32(binary.Size(types))
+	header := btfHeader{
+		Magic:     btfMagic,
+		Version:   1,
+		HdrLen:    minHeaderLength,
+		TypeOff:   0,
+		TypeLen:   typesLen,
+		StringOff: typesLen,
+		StringLen: uint32(len(strings)),
+	}
+
+	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() error {
+	var (
+		types struct {
+			Integer btfType
+			Var     btfType
+			btfVar  struct{ Linkage uint32 }
+		}
+		strings = []byte{0, 'a', 0}
+	)
+
+	// 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
+
+	btf := marshalBTF(&types, strings, internal.NativeEndian)
+
+	fd, err := bpfLoadBTF(&bpfLoadBTFAttr{
+		btf:     internal.NewSlicePointer(btf),
+		btfSize: uint32(len(btf)),
+	})
+	if errors.Is(err, unix.EINVAL) || errors.Is(err, unix.EPERM) {
+		// Treat both EINVAL and EPERM as not supported: loading the program
+		// might still succeed without BTF.
+		return internal.ErrNotSupported
+	}
+	if err != nil {
+		return err
+	}
+
+	fd.Close()
+	return nil
+})
+
+var haveFuncLinkage = internal.FeatureTest("BTF func linkage", "5.6", func() error {
+	if err := haveBTF(); err != nil {
+		return err
+	}
+
+	var (
+		types struct {
+			FuncProto btfType
+			Func      btfType
+		}
+		strings = []byte{0, 'a', 0}
+	)
+
+	types.FuncProto.SetKind(kindFuncProto)
+	types.Func.SetKind(kindFunc)
+	types.Func.SizeType = 1 // aka FuncProto
+	types.Func.NameOff = 1
+	types.Func.SetLinkage(linkageGlobal)
+
+	btf := marshalBTF(&types, strings, internal.NativeEndian)
+
+	fd, err := bpfLoadBTF(&bpfLoadBTFAttr{
+		btf:     internal.NewSlicePointer(btf),
+		btfSize: uint32(len(btf)),
+	})
+	if errors.Is(err, unix.EINVAL) {
+		return internal.ErrNotSupported
+	}
+	if err != nil {
+		return err
+	}
+
+	fd.Close()
+	return nil
+})
diff --git a/vendor/github.com/cilium/ebpf/internal/btf/btf_types.go b/vendor/github.com/cilium/ebpf/internal/btf/btf_types.go
new file mode 100644
index 000000000..a4cde3fe8
--- /dev/null
+++ b/vendor/github.com/cilium/ebpf/internal/btf/btf_types.go
@@ -0,0 +1,269 @@
+package btf
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+// 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
+)
+
+type btfFuncLinkage uint8
+
+const (
+	linkageStatic btfFuncLinkage = iota
+	linkageGlobal
+	linkageExtern
+)
+
+const (
+	btfTypeKindShift     = 24
+	btfTypeKindLen       = 4
+	btfTypeVlenShift     = 0
+	btfTypeVlenMask      = 16
+	btfTypeKindFlagShift = 31
+	btfTypeKindFlagMask  = 1
+)
+
+// 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), linkage
+	 * 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 (k btfKind) String() string {
+	switch k {
+	case kindUnknown:
+		return "Unknown"
+	case kindInt:
+		return "Integer"
+	case kindPointer:
+		return "Pointer"
+	case kindArray:
+		return "Array"
+	case kindStruct:
+		return "Struct"
+	case kindUnion:
+		return "Union"
+	case kindEnum:
+		return "Enumeration"
+	case kindForward:
+		return "Forward"
+	case kindTypedef:
+		return "Typedef"
+	case kindVolatile:
+		return "Volatile"
+	case kindConst:
+		return "Const"
+	case kindRestrict:
+		return "Restrict"
+	case kindFunc:
+		return "Function"
+	case kindFuncProto:
+		return "Function Proto"
+	case kindVar:
+		return "Variable"
+	case kindDatasec:
+		return "Section"
+	default:
+		return fmt.Sprintf("Unknown (%d)", k)
+	}
+}
+
+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) KindFlag() bool {
+	return bt.info(btfTypeKindFlagMask, btfTypeKindFlagShift) == 1
+}
+
+func (bt *btfType) Linkage() btfFuncLinkage {
+	return btfFuncLinkage(bt.info(btfTypeVlenMask, btfTypeVlenShift))
+}
+
+func (bt *btfType) SetLinkage(linkage btfFuncLinkage) {
+	bt.setInfo(uint32(linkage), 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
+}
+
+type btfVarSecinfo struct {
+	Type   TypeID
+	Offset uint32
+	Size   uint32
+}
+
+type btfVariable struct {
+	Linkage uint32
+}
+
+type btfEnum struct {
+	NameOff uint32
+	Val     int32
+}
+
+type btfParam struct {
+	NameOff uint32
+	Type    TypeID
+}
+
+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, fmt.Errorf("can't read type info for id %v: %v", id, err)
+		}
+
+		var data interface{}
+		switch header.Kind() {
+		case kindInt:
+			data = new(uint32)
+		case kindPointer:
+		case kindArray:
+			data = new(btfArray)
+		case kindStruct:
+			fallthrough
+		case kindUnion:
+			data = make([]btfMember, header.Vlen())
+		case kindEnum:
+			data = make([]btfEnum, header.Vlen())
+		case kindForward:
+		case kindTypedef:
+		case kindVolatile:
+		case kindConst:
+		case kindRestrict:
+		case kindFunc:
+		case kindFuncProto:
+			data = make([]btfParam, header.Vlen())
+		case kindVar:
+			data = new(btfVariable)
+		case kindDatasec:
+			data = make([]btfVarSecinfo, header.Vlen())
+		default:
+			return nil, fmt.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, fmt.Errorf("type id %d: kind %v: can't read %T: %v", id, header.Kind(), data, err)
+		}
+
+		types = append(types, rawType{header, data})
+	}
+}
+
+func intEncoding(raw uint32) (IntEncoding, uint32, byte) {
+	return IntEncoding((raw & 0x0f000000) >> 24), (raw & 0x00ff0000) >> 16, byte(raw & 0x000000ff)
+}
diff --git a/vendor/github.com/cilium/ebpf/internal/btf/core.go b/vendor/github.com/cilium/ebpf/internal/btf/core.go
new file mode 100644
index 000000000..52b59ed18
--- /dev/null
+++ b/vendor/github.com/cilium/ebpf/internal/btf/core.go
@@ -0,0 +1,388 @@
+package btf
+
+import (
+	"errors"
+	"fmt"
+	"reflect"
+	"strconv"
+	"strings"
+)
+
+// Code in this file is derived from libbpf, which is available under a BSD
+// 2-Clause license.
+
+// Relocation describes a CO-RE relocation.
+type Relocation struct {
+	Current uint32
+	New     uint32
+}
+
+func (r Relocation) equal(other Relocation) bool {
+	return r.Current == other.Current && r.New == other.New
+}
+
+// coreReloKind is the type of CO-RE relocation
+type coreReloKind uint32
+
+const (
+	reloFieldByteOffset coreReloKind = iota /* field byte offset */
+	reloFieldByteSize                       /* field size in bytes */
+	reloFieldExists                         /* field existence in target kernel */
+	reloFieldSigned                         /* field signedness (0 - unsigned, 1 - signed) */
+	reloFieldLShiftU64                      /* bitfield-specific left bitshift */
+	reloFieldRShiftU64                      /* bitfield-specific right bitshift */
+	reloTypeIDLocal                         /* type ID in local BPF object */
+	reloTypeIDTarget                        /* type ID in target kernel */
+	reloTypeExists                          /* type existence in target kernel */
+	reloTypeSize                            /* type size in bytes */
+	reloEnumvalExists                       /* enum value existence in target kernel */
+	reloEnumvalValue                        /* enum value integer value */
+)
+
+func (k coreReloKind) String() string {
+	switch k {
+	case reloFieldByteOffset:
+		return "byte_off"
+	case reloFieldByteSize:
+		return "byte_sz"
+	case reloFieldExists:
+		return "field_exists"
+	case reloFieldSigned:
+		return "signed"
+	case reloFieldLShiftU64:
+		return "lshift_u64"
+	case reloFieldRShiftU64:
+		return "rshift_u64"
+	case reloTypeIDLocal:
+		return "local_type_id"
+	case reloTypeIDTarget:
+		return "target_type_id"
+	case reloTypeExists:
+		return "type_exists"
+	case reloTypeSize:
+		return "type_size"
+	case reloEnumvalExists:
+		return "enumval_exists"
+	case reloEnumvalValue:
+		return "enumval_value"
+	default:
+		return "unknown"
+	}
+}
+
+func coreRelocate(local, target *Spec, coreRelos bpfCoreRelos) (map[uint64]Relocation, error) {
+	if target == nil {
+		var err error
+		target, err = loadKernelSpec()
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if local.byteOrder != target.byteOrder {
+		return nil, fmt.Errorf("can't relocate %s against %s", local.byteOrder, target.byteOrder)
+	}
+
+	relocations := make(map[uint64]Relocation, len(coreRelos))
+	for _, relo := range coreRelos {
+		accessorStr, err := local.strings.Lookup(relo.AccessStrOff)
+		if err != nil {
+			return nil, err
+		}
+
+		accessor, err := parseCoreAccessor(accessorStr)
+		if err != nil {
+			return nil, fmt.Errorf("accessor %q: %s", accessorStr, err)
+		}
+
+		if int(relo.TypeID) >= len(local.types) {
+			return nil, fmt.Errorf("invalid type id %d", relo.TypeID)
+		}
+
+		typ := local.types[relo.TypeID]
+
+		if relo.ReloKind == reloTypeIDLocal {
+			relocations[uint64(relo.InsnOff)] = Relocation{
+				uint32(typ.ID()),
+				uint32(typ.ID()),
+			}
+			continue
+		}
+
+		named, ok := typ.(namedType)
+		if !ok || named.name() == "" {
+			return nil, fmt.Errorf("relocate anonymous type %s: %w", typ.String(), ErrNotSupported)
+		}
+
+		name := essentialName(named.name())
+		res, err := coreCalculateRelocation(typ, target.namedTypes[name], relo.ReloKind, accessor)
+		if err != nil {
+			return nil, fmt.Errorf("relocate %s: %w", name, err)
+		}
+
+		relocations[uint64(relo.InsnOff)] = res
+	}
+
+	return relocations, nil
+}
+
+var errAmbiguousRelocation = errors.New("ambiguous relocation")
+
+func coreCalculateRelocation(local Type, targets []namedType, kind coreReloKind, localAccessor coreAccessor) (Relocation, error) {
+	var relos []Relocation
+	var matches []Type
+	for _, target := range targets {
+		switch kind {
+		case reloTypeIDTarget:
+			if localAccessor[0] != 0 {
+				return Relocation{}, fmt.Errorf("%s: unexpected non-zero accessor", kind)
+			}
+
+			if compat, err := coreAreTypesCompatible(local, target); err != nil {
+				return Relocation{}, fmt.Errorf("%s: %s", kind, err)
+			} else if !compat {
+				continue
+			}
+
+			relos = append(relos, Relocation{uint32(target.ID()), uint32(target.ID())})
+
+		default:
+			return Relocation{}, fmt.Errorf("relocation %s: %w", kind, ErrNotSupported)
+		}
+		matches = append(matches, target)
+	}
+
+	if len(relos) == 0 {
+		// TODO: Add switch for existence checks like reloEnumvalExists here.
+
+		// TODO: This might have to be poisoned.
+		return Relocation{}, fmt.Errorf("no relocation found, tried %v", targets)
+	}
+
+	relo := relos[0]
+	for _, altRelo := range relos[1:] {
+		if !altRelo.equal(relo) {
+			return Relocation{}, fmt.Errorf("multiple types %v match: %w", matches, errAmbiguousRelocation)
+		}
+	}
+
+	return relo, nil
+}
+
+/* coreAccessor contains a path through a struct. It contains at least one index.
+ *
+ * The interpretation depends on the kind of the relocation. The following is
+ * taken from struct bpf_core_relo in libbpf_internal.h:
+ *
+ * - for field-based relocations, string encodes an accessed field using
+ *   a sequence of field and array indices, separated by colon (:). It's
+ *   conceptually very close to LLVM's getelementptr ([0]) instruction's
+ *   arguments for identifying offset to a field.
+ * - for type-based relocations, strings is expected to be just "0";
+ * - for enum value-based relocations, string contains an index of enum
+ *   value within its enum type;
+ *
+ * Example to provide a better feel.
+ *
+ *   struct sample {
+ *       int a;
+ *       struct {
+ *           int b[10];
+ *       };
+ *   };
+ *
+ *   struct sample s = ...;
+ *   int x = &s->a;     // encoded as "0:0" (a is field #0)
+ *   int y = &s->b[5];  // encoded as "0:1:0:5" (anon struct is field #1,
+ *                      // b is field #0 inside anon struct, accessing elem #5)
+ *   int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array)
+ */
+type coreAccessor []int
+
+func parseCoreAccessor(accessor string) (coreAccessor, error) {
+	if accessor == "" {
+		return nil, fmt.Errorf("empty accessor")
+	}
+
+	var result coreAccessor
+	parts := strings.Split(accessor, ":")
+	for _, part := range parts {
+		// 31 bits to avoid overflowing int on 32 bit platforms.
+		index, err := strconv.ParseUint(part, 10, 31)
+		if err != nil {
+			return nil, fmt.Errorf("accessor index %q: %s", part, err)
+		}
+
+		result = append(result, int(index))
+	}
+
+	return result, nil
+}
+
+/* The comment below is from bpf_core_types_are_compat in libbpf.c:
+ *
+ * Check local and target types for compatibility. This check is used for
+ * type-based CO-RE relocations and follow slightly different rules than
+ * field-based relocations. This function assumes that root types were already
+ * checked for name match. Beyond that initial root-level name check, names
+ * are completely ignored. Compatibility rules are as follows:
+ *   - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs are considered compatible, but
+ *     kind should match for local and target types (i.e., STRUCT is not
+ *     compatible with UNION);
+ *   - for ENUMs, the size is ignored;
+ *   - for INT, size and signedness are ignored;
+ *   - for ARRAY, dimensionality is ignored, element types are checked for
+ *     compatibility recursively;
+ *   - CONST/VOLATILE/RESTRICT modifiers are ignored;
+ *   - TYPEDEFs/PTRs are compatible if types they pointing to are compatible;
+ *   - FUNC_PROTOs are compatible if they have compatible signature: same
+ *     number of input args and compatible return and argument types.
+ * These rules are not set in stone and probably will be adjusted as we get
+ * more experience with using BPF CO-RE relocations.
+ */
+func coreAreTypesCompatible(localType Type, targetType Type) (bool, error) {
+	var (
+		localTs, targetTs typeDeque
+		l, t              = &localType, &targetType
+		depth             = 0
+	)
+
+	for ; l != nil && t != nil; l, t = localTs.shift(), targetTs.shift() {
+		if depth >= maxTypeDepth {
+			return false, errors.New("types are nested too deep")
+		}
+
+		localType = skipQualifierAndTypedef(*l)
+		targetType = skipQualifierAndTypedef(*t)
+
+		if reflect.TypeOf(localType) != reflect.TypeOf(targetType) {
+			return false, nil
+		}
+
+		switch lv := (localType).(type) {
+		case *Void, *Struct, *Union, *Enum, *Fwd:
+			// Nothing to do here
+
+		case *Int:
+			tv := targetType.(*Int)
+			if lv.isBitfield() || tv.isBitfield() {
+				return false, nil
+			}
+
+		case *Pointer, *Array:
+			depth++
+			localType.walk(&localTs)
+			targetType.walk(&targetTs)
+
+		case *FuncProto:
+			tv := targetType.(*FuncProto)
+			if len(lv.Params) != len(tv.Params) {
+				return false, nil
+			}
+
+			depth++
+			localType.walk(&localTs)
+			targetType.walk(&targetTs)
+
+		default:
+			return false, fmt.Errorf("unsupported type %T", localType)
+		}
+	}
+
+	if l != nil {
+		return false, fmt.Errorf("dangling local type %T", *l)
+	}
+
+	if t != nil {
+		return false, fmt.Errorf("dangling target type %T", *t)
+	}
+
+	return true, nil
+}
+
+/* The comment below is from bpf_core_fields_are_compat in libbpf.c:
+ *
+ * Check two types for compatibility for the purpose of field access
+ * relocation. const/volatile/restrict and typedefs are skipped to ensure we
+ * are relocating semantically compatible entities:
+ *   - any two STRUCTs/UNIONs are compatible and can be mixed;
+ *   - any two FWDs are compatible, if their names match (modulo flavor suffix);
+ *   - any two PTRs are always compatible;
+ *   - for ENUMs, names should be the same (ignoring flavor suffix) or at
+ *     least one of enums should be anonymous;
+ *   - for ENUMs, check sizes, names are ignored;
+ *   - for INT, size and signedness are ignored;
+ *   - for ARRAY, dimensionality is ignored, element types are checked for
+ *     compatibility recursively;
+ *   - everything else shouldn't be ever a target of relocation.
+ * These rules are not set in stone and probably will be adjusted as we get
+ * more experience with using BPF CO-RE relocations.
+ */
+func coreAreMembersCompatible(localType Type, targetType Type) (bool, error) {
+	doNamesMatch := func(a, b string) bool {
+		if a == "" || b == "" {
+			// allow anonymous and named type to match
+			return true
+		}
+
+		return essentialName(a) == essentialName(b)
+	}
+
+	for depth := 0; depth <= maxTypeDepth; depth++ {
+		localType = skipQualifierAndTypedef(localType)
+		targetType = skipQualifierAndTypedef(targetType)
+
+		_, lok := localType.(composite)
+		_, tok := targetType.(composite)
+		if lok && tok {
+			return true, nil
+		}
+
+		if reflect.TypeOf(localType) != reflect.TypeOf(targetType) {
+			return false, nil
+		}
+
+		switch lv := localType.(type) {
+		case *Pointer:
+			return true, nil
+
+		case *Enum:
+			tv := targetType.(*Enum)
+			return doNamesMatch(lv.name(), tv.name()), nil
+
+		case *Fwd:
+			tv := targetType.(*Fwd)
+			return doNamesMatch(lv.name(), tv.name()), nil
+
+		case *Int:
+			tv := targetType.(*Int)
+			return !lv.isBitfield() && !tv.isBitfield(), nil
+
+		case *Array:
+			tv := targetType.(*Array)
+
+			localType = lv.Type
+			targetType = tv.Type
+
+		default:
+			return false, fmt.Errorf("unsupported type %T", localType)
+		}
+	}
+
+	return false, errors.New("types are nested too deep")
+}
+
+func skipQualifierAndTypedef(typ Type) Type {
+	result := typ
+	for depth := 0; depth <= maxTypeDepth; depth++ {
+		switch v := (result).(type) {
+		case qualifier:
+			result = v.qualify()
+		case *Typedef:
+			result = v.Type
+		default:
+			return result
+		}
+	}
+	return typ
+}
diff --git a/vendor/github.com/cilium/ebpf/internal/btf/doc.go b/vendor/github.com/cilium/ebpf/internal/btf/doc.go
new file mode 100644
index 000000000..ad2576cb2
--- /dev/null
+++ b/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
diff --git a/vendor/github.com/cilium/ebpf/internal/btf/ext_info.go b/vendor/github.com/cilium/ebpf/internal/btf/ext_info.go
new file mode 100644
index 000000000..6a21b6bda
--- /dev/null
+++ b/vendor/github.com/cilium/ebpf/internal/btf/ext_info.go
@@ -0,0 +1,281 @@
+package btf
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+
+	"github.com/cilium/ebpf/asm"
+	"github.com/cilium/ebpf/internal"
+)
+
+type btfExtHeader struct {
+	Magic   uint16
+	Version uint8
+	Flags   uint8
+	HdrLen  uint32
+
+	FuncInfoOff uint32
+	FuncInfoLen uint32
+	LineInfoOff uint32
+	LineInfoLen uint32
+}
+
+type btfExtCoreHeader struct {
+	CoreReloOff uint32
+	CoreReloLen uint32
+}
+
+func parseExtInfos(r io.ReadSeeker, bo binary.ByteOrder, strings stringTable) (funcInfo, lineInfo map[string]extInfo, coreRelos map[string]bpfCoreRelos, err error) {
+	var header btfExtHeader
+	var coreHeader btfExtCoreHeader
+	if err := binary.Read(r, bo, &header); err != nil {
+		return nil, nil, nil, fmt.Errorf("can't read header: %v", err)
+	}
+
+	if header.Magic != btfMagic {
+		return nil, nil, nil, fmt.Errorf("incorrect magic value %v", header.Magic)
+	}
+
+	if header.Version != 1 {
+		return nil, nil, nil, fmt.Errorf("unexpected version %v", header.Version)
+	}
+
+	if header.Flags != 0 {
+		return nil, nil, nil, fmt.Errorf("unsupported flags %v", header.Flags)
+	}
+
+	remainder := int64(header.HdrLen) - int64(binary.Size(&header))
+	if remainder < 0 {
+		return nil, nil, nil, errors.New("header is too short")
+	}
+
+	coreHdrSize := int64(binary.Size(&coreHeader))
+	if remainder >= coreHdrSize {
+		if err := binary.Read(r, bo, &coreHeader); err != nil {
+			return nil, nil, nil, fmt.Errorf("can't read CO-RE relocation header: %v", err)
+		}
+		remainder -= coreHdrSize
+	}
+
+	// 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, nil, fmt.Errorf("header padding: %v", err)
+	}
+
+	if _, err := r.Seek(int64(header.HdrLen+header.FuncInfoOff), io.SeekStart); err != nil {
+		return nil, nil, nil, fmt.Errorf("can't seek to function info section: %v", err)
+	}
+
+	buf := bufio.NewReader(io.LimitReader(r, int64(header.FuncInfoLen)))
+	funcInfo, err = parseExtInfo(buf, bo, strings)
+	if err != nil {
+		return nil, nil, nil, fmt.Errorf("function info: %w", err)
+	}
+
+	if _, err := r.Seek(int64(header.HdrLen+header.LineInfoOff), io.SeekStart); err != nil {
+		return nil, nil, nil, fmt.Errorf("can't seek to line info section: %v", err)
+	}
+
+	buf = bufio.NewReader(io.LimitReader(r, int64(header.LineInfoLen)))
+	lineInfo, err = parseExtInfo(buf, bo, strings)
+	if err != nil {
+		return nil, nil, nil, fmt.Errorf("line info: %w", err)
+	}
+
+	if coreHeader.CoreReloOff > 0 && coreHeader.CoreReloLen > 0 {
+		if _, err := r.Seek(int64(header.HdrLen+coreHeader.CoreReloOff), io.SeekStart); err != nil {
+			return nil, nil, nil, fmt.Errorf("can't seek to CO-RE relocation section: %v", err)
+		}
+
+		coreRelos, err = parseExtInfoRelos(io.LimitReader(r, int64(coreHeader.CoreReloLen)), bo, strings)
+		if err != nil {
+			return nil, nil, nil, fmt.Errorf("CO-RE relocation info: %w", err)
+		}
+	}
+
+	return funcInfo, lineInfo, coreRelos, 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{}, fmt.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, fmt.Errorf("can't write instruction offset: %v", err)
+		}
+
+		buf.Write(info.Opaque)
+	}
+
+	return buf.Bytes(), nil
+}
+
+func parseExtInfo(r io.Reader, bo binary.ByteOrder, strings stringTable) (map[string]extInfo, error) {
+	const maxRecordSize = 256
+
+	var recordSize uint32
+	if err := binary.Read(r, bo, &recordSize); err != nil {
+		return nil, fmt.Errorf("can't read record size: %v", err)
+	}
+
+	if recordSize < 4 {
+		// Need at least insnOff
+		return nil, errors.New("record size too short")
+	}
+	if recordSize > maxRecordSize {
+		return nil, fmt.Errorf("record size %v exceeds %v", recordSize, maxRecordSize)
+	}
+
+	result := make(map[string]extInfo)
+	for {
+		secName, infoHeader, err := parseExtInfoHeader(r, bo, strings)
+		if errors.Is(err, io.EOF) {
+			return result, nil
+		}
+
+		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, fmt.Errorf("section %v: can't read extended info offset: %v", secName, err)
+			}
+
+			buf := make([]byte, int(recordSize-4))
+			if _, err := io.ReadFull(r, buf); err != nil {
+				return nil, fmt.Errorf("section %v: can't read record: %v", secName, err)
+			}
+
+			if byteOff%asm.InstructionSize != 0 {
+				return nil, fmt.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,
+		}
+	}
+}
+
+// bpfCoreRelo matches `struct bpf_core_relo` from the kernel
+type bpfCoreRelo struct {
+	InsnOff      uint32
+	TypeID       TypeID
+	AccessStrOff uint32
+	ReloKind     coreReloKind
+}
+
+type bpfCoreRelos []bpfCoreRelo
+
+// append two slices of extInfoRelo to each other. The InsnOff of b are adjusted
+// by offset.
+func (r bpfCoreRelos) append(other bpfCoreRelos, offset uint64) bpfCoreRelos {
+	result := make([]bpfCoreRelo, 0, len(r)+len(other))
+	result = append(result, r...)
+	for _, relo := range other {
+		relo.InsnOff += uint32(offset)
+		result = append(result, relo)
+	}
+	return result
+}
+
+var extInfoReloSize = binary.Size(bpfCoreRelo{})
+
+func parseExtInfoRelos(r io.Reader, bo binary.ByteOrder, strings stringTable) (map[string]bpfCoreRelos, error) {
+	var recordSize uint32
+	if err := binary.Read(r, bo, &recordSize); err != nil {
+		return nil, fmt.Errorf("read record size: %v", err)
+	}
+
+	if recordSize != uint32(extInfoReloSize) {
+		return nil, fmt.Errorf("expected record size %d, got %d", extInfoReloSize, recordSize)
+	}
+
+	result := make(map[string]bpfCoreRelos)
+	for {
+		secName, infoHeader, err := parseExtInfoHeader(r, bo, strings)
+		if errors.Is(err, io.EOF) {
+			return result, nil
+		}
+
+		var relos []bpfCoreRelo
+		for i := uint32(0); i < infoHeader.NumInfo; i++ {
+			var relo bpfCoreRelo
+			if err := binary.Read(r, bo, &relo); err != nil {
+				return nil, fmt.Errorf("section %v: read record: %v", secName, err)
+			}
+
+			if relo.InsnOff%asm.InstructionSize != 0 {
+				return nil, fmt.Errorf("section %v: offset %v is not aligned with instruction size", secName, relo.InsnOff)
+			}
+
+			relos = append(relos, relo)
+		}
+
+		result[secName] = relos
+	}
+}
+
+func parseExtInfoHeader(r io.Reader, bo binary.ByteOrder, strings stringTable) (string, *btfExtInfoSec, error) {
+	var infoHeader btfExtInfoSec
+	if err := binary.Read(r, bo, &infoHeader); err != nil {
+		return "", nil, fmt.Errorf("read ext info header: %w", err)
+	}
+
+	secName, err := strings.Lookup(infoHeader.SecNameOff)
+	if err != nil {
+		return "", nil, fmt.Errorf("get section name: %w", err)
+	}
+
+	if infoHeader.NumInfo == 0 {
+		return "", nil, fmt.Errorf("section %s has zero records", secName)
+	}
+
+	return secName, &infoHeader, nil
+}
diff --git a/vendor/github.com/cilium/ebpf/internal/btf/fuzz.go b/vendor/github.com/cilium/ebpf/internal/btf/fuzz.go
new file mode 100644
index 000000000..37e043fd3
--- /dev/null
+++ b/vendor/github.com/cilium/ebpf/internal/btf/fuzz.go
@@ -0,0 +1,49 @@
+// +build gofuzz
+
+// Use with https://github.com/dvyukov/go-fuzz
+
+package btf
+
+import (
+	"bytes"
+	"encoding/binary"
+
+	"github.com/cilium/ebpf/internal"
+)
+
+func FuzzSpec(data []byte) int {
+	if len(data) < binary.Size(btfHeader{}) {
+		return -1
+	}
+
+	spec, err := loadNakedSpec(bytes.NewReader(data), internal.NativeEndian, nil, nil)
+	if err != nil {
+		if spec != nil {
+			panic("spec is not nil")
+		}
+		return 0
+	}
+	if spec == nil {
+		panic("spec is nil")
+	}
+	return 1
+}
+
+func FuzzExtInfo(data []byte) int {
+	if len(data) < binary.Size(btfExtHeader{}) {
+		return -1
+	}
+
+	table := stringTable("\x00foo\x00barfoo\x00")
+	info, err := parseExtInfo(bytes.NewReader(data), internal.NativeEndian, table)
+	if err != nil {
+		if info != nil {
+			panic("info is not nil")
+		}
+		return 0
+	}
+	if info == nil {
+		panic("info is nil")
+	}
+	return 1
+}
diff --git a/vendor/github.com/cilium/ebpf/internal/btf/strings.go b/vendor/github.com/cilium/ebpf/internal/btf/strings.go
new file mode 100644
index 000000000..8782643a0
--- /dev/null
+++ b/vendor/github.com/cilium/ebpf/internal/btf/strings.go
@@ -0,0 +1,60 @@
+package btf
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+)
+
+type stringTable []byte
+
+func readStringTable(r io.Reader) (stringTable, error) {
+	contents, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, fmt.Errorf("can't read string table: %v", err)
+	}
+
+	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 "", fmt.Errorf("offset %d overflows int", offset)
+	}
+
+	pos := int(offset)
+	if pos >= len(st) {
+		return "", fmt.Errorf("offset %d is out of bounds", offset)
+	}
+
+	if pos > 0 && st[pos-1] != '\x00' {
+		return "", fmt.Errorf("offset %d isn't start of a string", offset)
+	}
+
+	str := st[pos:]
+	end := bytes.IndexByte(str, '\x00')
+	if end == -1 {
+		return "", fmt.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
+}
diff --git a/vendor/github.com/cilium/ebpf/internal/btf/types.go b/vendor/github.com/cilium/ebpf/internal/btf/types.go
new file mode 100644
index 000000000..9e1fd8d0b
--- /dev/null
+++ b/vendor/github.com/cilium/ebpf/internal/btf/types.go
@@ -0,0 +1,871 @@
+package btf
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"strings"
+)
+
+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
+
+	String() string
+
+	// Make a copy of the type, without copying Type members.
+	copy() Type
+
+	// Enumerate all nested Types. Repeated calls must visit nested
+	// types in the same order.
+	walk(*typeDeque)
+}
+
+// namedType is a type with a name.
+//
+// Most named types simply embed Name.
+type namedType interface {
+	Type
+	name() string
+}
+
+// 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) String() string  { return "void#0" }
+func (v *Void) size() uint32    { return 0 }
+func (v *Void) copy() Type      { return (*Void)(nil) }
+func (v *Void) walk(*typeDeque) {}
+
+type IntEncoding byte
+
+const (
+	Signed IntEncoding = 1 << iota
+	Char
+	Bool
+)
+
+// Int is an integer of a given length.
+type Int struct {
+	TypeID
+	Name
+
+	// The size of the integer in bytes.
+	Size     uint32
+	Encoding IntEncoding
+	// Offset is the starting bit offset. Currently always 0.
+	// See https://www.kernel.org/doc/html/latest/bpf/btf.html#btf-kind-int
+	Offset uint32
+	Bits   byte
+}
+
+var _ namedType = (*Int)(nil)
+
+func (i *Int) String() string {
+	var s strings.Builder
+
+	switch {
+	case i.Encoding&Char != 0:
+		s.WriteString("char")
+	case i.Encoding&Bool != 0:
+		s.WriteString("bool")
+	default:
+		if i.Encoding&Signed == 0 {
+			s.WriteRune('u')
+		}
+		s.WriteString("int")
+		fmt.Fprintf(&s, "%d", i.Size*8)
+	}
+
+	fmt.Fprintf(&s, "#%d", i.TypeID)
+
+	if i.Bits > 0 {
+		fmt.Fprintf(&s, "[bits=%d]", i.Bits)
+	}
+
+	return s.String()
+}
+
+func (i *Int) size() uint32    { return i.Size }
+func (i *Int) walk(*typeDeque) {}
+func (i *Int) copy() Type {
+	cpy := *i
+	return &cpy
+}
+
+func (i *Int) isBitfield() bool {
+	return i.Offset > 0
+}
+
+// Pointer is a pointer to another type.
+type Pointer struct {
+	TypeID
+	Target Type
+}
+
+func (p *Pointer) String() string {
+	return fmt.Sprintf("pointer#%d[target=#%d]", p.TypeID, p.Target.ID())
+}
+
+func (p *Pointer) size() uint32        { return 8 }
+func (p *Pointer) walk(tdq *typeDeque) { tdq.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) String() string {
+	return fmt.Sprintf("array#%d[type=#%d n=%d]", arr.TypeID, arr.Type.ID(), arr.Nelems)
+}
+
+func (arr *Array) walk(tdq *typeDeque) { tdq.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) String() string {
+	return fmt.Sprintf("struct#%d[%q]", s.TypeID, s.Name)
+}
+
+func (s *Struct) size() uint32 { return s.Size }
+
+func (s *Struct) walk(tdq *typeDeque) {
+	for i := range s.Members {
+		tdq.push(&s.Members[i].Type)
+	}
+}
+
+func (s *Struct) copy() Type {
+	cpy := *s
+	cpy.Members = make([]Member, len(s.Members))
+	copy(cpy.Members, s.Members)
+	return &cpy
+}
+
+func (s *Struct) members() []Member {
+	return s.Members
+}
+
+// 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) String() string {
+	return fmt.Sprintf("union#%d[%q]", u.TypeID, u.Name)
+}
+
+func (u *Union) size() uint32 { return u.Size }
+
+func (u *Union) walk(tdq *typeDeque) {
+	for i := range u.Members {
+		tdq.push(&u.Members[i].Type)
+	}
+}
+
+func (u *Union) copy() Type {
+	cpy := *u
+	cpy.Members = make([]Member, len(u.Members))
+	copy(cpy.Members, u.Members)
+	return &cpy
+}
+
+func (u *Union) members() []Member {
+	return u.Members
+}
+
+type composite interface {
+	members() []Member
+}
+
+var (
+	_ composite = (*Struct)(nil)
+	_ composite = (*Union)(nil)
+)
+
+// Member is part of a Struct or Union.
+//
+// It is not a valid Type.
+type Member struct {
+	Name
+	Type Type
+	// Offset is the bit offset of this member
+	Offset       uint32
+	BitfieldSize uint32
+}
+
+// Enum lists possible values.
+type Enum struct {
+	TypeID
+	Name
+	Values []EnumValue
+}
+
+func (e *Enum) String() string {
+	return fmt.Sprintf("enum#%d[%q]", e.TypeID, e.Name)
+}
+
+// EnumValue is part of an Enum
+//
+// Is is not a valid Type
+type EnumValue struct {
+	Name
+	Value int32
+}
+
+func (e *Enum) size() uint32    { return 4 }
+func (e *Enum) walk(*typeDeque) {}
+func (e *Enum) copy() Type {
+	cpy := *e
+	cpy.Values = make([]EnumValue, len(e.Values))
+	copy(cpy.Values, e.Values)
+	return &cpy
+}
+
+// FwdKind is the type of forward declaration.
+type FwdKind int
+
+// Valid types of forward declaration.
+const (
+	FwdStruct FwdKind = iota
+	FwdUnion
+)
+
+func (fk FwdKind) String() string {
+	switch fk {
+	case FwdStruct:
+		return "struct"
+	case FwdUnion:
+		return "union"
+	default:
+		return fmt.Sprintf("%T(%d)", fk, int(fk))
+	}
+}
+
+// Fwd is a forward declaration of a Type.
+type Fwd struct {
+	TypeID
+	Name
+	Kind FwdKind
+}
+
+func (f *Fwd) String() string {
+	return fmt.Sprintf("fwd#%d[%s %q]", f.TypeID, f.Kind, f.Name)
+}
+
+func (f *Fwd) walk(*typeDeque) {}
+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) String() string {
+	return fmt.Sprintf("typedef#%d[%q #%d]", td.TypeID, td.Name, td.Type.ID())
+}
+
+func (td *Typedef) walk(tdq *typeDeque) { tdq.push(&td.Type) }
+func (td *Typedef) copy() Type {
+	cpy := *td
+	return &cpy
+}
+
+// Volatile is a qualifier.
+type Volatile struct {
+	TypeID
+	Type Type
+}
+
+func (v *Volatile) String() string {
+	return fmt.Sprintf("volatile#%d[#%d]", v.TypeID, v.Type.ID())
+}
+
+func (v *Volatile) qualify() Type       { return v.Type }
+func (v *Volatile) walk(tdq *typeDeque) { tdq.push(&v.Type) }
+func (v *Volatile) copy() Type {
+	cpy := *v
+	return &cpy
+}
+
+// Const is a qualifier.
+type Const struct {
+	TypeID
+	Type Type
+}
+
+func (c *Const) String() string {
+	return fmt.Sprintf("const#%d[#%d]", c.TypeID, c.Type.ID())
+}
+
+func (c *Const) qualify() Type       { return c.Type }
+func (c *Const) walk(tdq *typeDeque) { tdq.push(&c.Type) }
+func (c *Const) copy() Type {
+	cpy := *c
+	return &cpy
+}
+
+// Restrict is a qualifier.
+type Restrict struct {
+	TypeID
+	Type Type
+}
+
+func (r *Restrict) String() string {
+	return fmt.Sprintf("restrict#%d[#%d]", r.TypeID, r.Type.ID())
+}
+
+func (r *Restrict) qualify() Type       { return r.Type }
+func (r *Restrict) walk(tdq *typeDeque) { tdq.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) String() string {
+	return fmt.Sprintf("func#%d[%q proto=#%d]", f.TypeID, f.Name, f.Type.ID())
+}
+
+func (f *Func) walk(tdq *typeDeque) { tdq.push(&f.Type) }
+func (f *Func) copy() Type {
+	cpy := *f
+	return &cpy
+}
+
+// FuncProto is a function declaration.
+type FuncProto struct {
+	TypeID
+	Return Type
+	Params []FuncParam
+}
+
+func (fp *FuncProto) String() string {
+	var s strings.Builder
+	fmt.Fprintf(&s, "proto#%d[", fp.TypeID)
+	for _, param := range fp.Params {
+		fmt.Fprintf(&s, "%q=#%d, ", param.Name, param.Type.ID())
+	}
+	fmt.Fprintf(&s, "return=#%d]", fp.Return.ID())
+	return s.String()
+}
+
+func (fp *FuncProto) walk(tdq *typeDeque) {
+	tdq.push(&fp.Return)
+	for i := range fp.Params {
+		tdq.push(&fp.Params[i].Type)
+	}
+}
+
+func (fp *FuncProto) copy() Type {
+	cpy := *fp
+	cpy.Params = make([]FuncParam, len(fp.Params))
+	copy(cpy.Params, fp.Params)
+	return &cpy
+}
+
+type FuncParam struct {
+	Name
+	Type Type
+}
+
+// Var is a global variable.
+type Var struct {
+	TypeID
+	Name
+	Type Type
+}
+
+func (v *Var) String() string {
+	// TODO: Linkage
+	return fmt.Sprintf("var#%d[%q]", v.TypeID, v.Name)
+}
+
+func (v *Var) walk(tdq *typeDeque) { tdq.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
+	Vars []VarSecinfo
+}
+
+func (ds *Datasec) String() string {
+	return fmt.Sprintf("section#%d[%q]", ds.TypeID, ds.Name)
+}
+
+func (ds *Datasec) size() uint32 { return ds.Size }
+
+func (ds *Datasec) walk(tdq *typeDeque) {
+	for i := range ds.Vars {
+		tdq.push(&ds.Vars[i].Type)
+	}
+}
+
+func (ds *Datasec) copy() Type {
+	cpy := *ds
+	cpy.Vars = make([]VarSecinfo, len(ds.Vars))
+	copy(cpy.Vars, ds.Vars)
+	return &cpy
+}
+
+// VarSecinfo describes variable in a Datasec
+//
+// It is not a valid Type.
+type VarSecinfo struct {
+	Type   Type
+	Offset uint32
+	Size   uint32
+}
+
+type sizer interface {
+	size() uint32
+}
+
+var (
+	_ sizer = (*Int)(nil)
+	_ sizer = (*Pointer)(nil)
+	_ sizer = (*Struct)(nil)
+	_ sizer = (*Union)(nil)
+	_ sizer = (*Enum)(nil)
+	_ sizer = (*Datasec)(nil)
+)
+
+type qualifier interface {
+	qualify() Type
+}
+
+var (
+	_ qualifier = (*Const)(nil)
+	_ qualifier = (*Restrict)(nil)
+	_ qualifier = (*Volatile)(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 qualifier:
+			typ = v.qualify()
+			continue
+
+		default:
+			return 0, fmt.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   typeDeque
+	)
+
+	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
+}
+
+// typeDeque keeps track of pointers to types which still
+// need to be visited.
+type typeDeque struct {
+	types       []*Type
+	read, write uint64
+	mask        uint64
+}
+
+// push adds a type to the stack.
+func (dq *typeDeque) push(t *Type) {
+	if dq.write-dq.read < uint64(len(dq.types)) {
+		dq.types[dq.write&dq.mask] = t
+		dq.write++
+		return
+	}
+
+	new := len(dq.types) * 2
+	if new == 0 {
+		new = 8
+	}
+
+	types := make([]*Type, new)
+	pivot := dq.read & dq.mask
+	n := copy(types, dq.types[pivot:])
+	n += copy(types[n:], dq.types[:pivot])
+	types[n] = t
+
+	dq.types = types
+	dq.mask = uint64(new) - 1
+	dq.read, dq.write = 0, uint64(n+1)
+}
+
+// shift returns the first element or null.
+func (dq *typeDeque) shift() *Type {
+	if dq.read == dq.write {
+		return nil
+	}
+
+	index := dq.read & dq.mask
+	t := dq.types[index]
+	dq.types[index] = nil
+	dq.read++
+	return t
+}
+
+// pop returns the last element or null.
+func (dq *typeDeque) pop() *Type {
+	if dq.read == dq.write {
+		return nil
+	}
+
+	dq.write--
+	index := dq.write & dq.mask
+	t := dq.types[index]
+	dq.types[index] = nil
+	return t
+}
+
+// all returns all elements.
+//
+// The deque is empty after calling this method.
+func (dq *typeDeque) all() []*Type {
+	length := dq.write - dq.read
+	types := make([]*Type, 0, length)
+	for t := dq.shift(); t != nil; t = dq.shift() {
+		types = append(types, t)
+	}
+	return types
+}
+
+// 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) and a slice of types
+// indexed by TypeID. 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) (types []Type, namedTypes map[string][]namedType, err error) {
+	type fixupDef struct {
+		id           TypeID
+		expectedKind btfKind
+		typ          *Type
+	}
+
+	var fixups []fixupDef
+	fixup := func(id TypeID, expectedKind btfKind, typ *Type) {
+		fixups = append(fixups, fixupDef{id, expectedKind, typ})
+	}
+
+	convertMembers := func(raw []btfMember, kindFlag bool) ([]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, fmt.Errorf("can't get name for member %d: %w", i, err)
+			}
+			m := Member{
+				Name:   name,
+				Offset: btfMember.Offset,
+			}
+			if kindFlag {
+				m.BitfieldSize = btfMember.Offset >> 24
+				m.Offset &= 0xffffff
+			}
+			members = append(members, m)
+		}
+		for i := range members {
+			fixup(raw[i].Type, kindUnknown, &members[i].Type)
+		}
+		return members, nil
+	}
+
+	types = make([]Type, 0, len(rawTypes))
+	types = append(types, (*Void)(nil))
+	namedTypes = make(map[string][]namedType)
+
+	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, nil, fmt.Errorf("get name for type id %d: %w", id, err)
+		}
+
+		switch raw.Kind() {
+		case kindInt:
+			encoding, offset, bits := intEncoding(*raw.data.(*uint32))
+			typ = &Int{id, name, raw.Size(), encoding, offset, bits}
+
+		case kindPointer:
+			ptr := &Pointer{id, nil}
+			fixup(raw.Type(), kindUnknown, &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}
+			fixup(btfArr.Type, kindUnknown, &arr.Type)
+			typ = arr
+
+		case kindStruct:
+			members, err := convertMembers(raw.data.([]btfMember), raw.KindFlag())
+			if err != nil {
+				return nil, nil, fmt.Errorf("struct %s (id %d): %w", name, id, err)
+			}
+			typ = &Struct{id, name, raw.Size(), members}
+
+		case kindUnion:
+			members, err := convertMembers(raw.data.([]btfMember), raw.KindFlag())
+			if err != nil {
+				return nil, nil, fmt.Errorf("union %s (id %d): %w", name, id, err)
+			}
+			typ = &Union{id, name, raw.Size(), members}
+
+		case kindEnum:
+			rawvals := raw.data.([]btfEnum)
+			vals := make([]EnumValue, 0, len(rawvals))
+			for i, btfVal := range rawvals {
+				name, err := rawStrings.LookupName(btfVal.NameOff)
+				if err != nil {
+					return nil, nil, fmt.Errorf("get name for enum value %d: %s", i, err)
+				}
+				vals = append(vals, EnumValue{
+					Name:  name,
+					Value: btfVal.Val,
+				})
+			}
+			typ = &Enum{id, name, vals}
+
+		case kindForward:
+			if raw.KindFlag() {
+				typ = &Fwd{id, name, FwdUnion}
+			} else {
+				typ = &Fwd{id, name, FwdStruct}
+			}
+
+		case kindTypedef:
+			typedef := &Typedef{id, name, nil}
+			fixup(raw.Type(), kindUnknown, &typedef.Type)
+			typ = typedef
+
+		case kindVolatile:
+			volatile := &Volatile{id, nil}
+			fixup(raw.Type(), kindUnknown, &volatile.Type)
+			typ = volatile
+
+		case kindConst:
+			cnst := &Const{id, nil}
+			fixup(raw.Type(), kindUnknown, &cnst.Type)
+			typ = cnst
+
+		case kindRestrict:
+			restrict := &Restrict{id, nil}
+			fixup(raw.Type(), kindUnknown, &restrict.Type)
+			typ = restrict
+
+		case kindFunc:
+			fn := &Func{id, name, nil}
+			fixup(raw.Type(), kindFuncProto, &fn.Type)
+			typ = fn
+
+		case kindFuncProto:
+			rawparams := raw.data.([]btfParam)
+			params := make([]FuncParam, 0, len(rawparams))
+			for i, param := range rawparams {
+				name, err := rawStrings.LookupName(param.NameOff)
+				if err != nil {
+					return nil, nil, fmt.Errorf("get name for func proto parameter %d: %s", i, err)
+				}
+				params = append(params, FuncParam{
+					Name: name,
+				})
+			}
+			for i := range params {
+				fixup(rawparams[i].Type, kindUnknown, &params[i].Type)
+			}
+
+			fp := &FuncProto{id, nil, params}
+			fixup(raw.Type(), kindUnknown, &fp.Return)
+			typ = fp
+
+		case kindVar:
+			v := &Var{id, name, nil}
+			fixup(raw.Type(), kindUnknown, &v.Type)
+			typ = v
+
+		case kindDatasec:
+			btfVars := raw.data.([]btfVarSecinfo)
+			vars := make([]VarSecinfo, 0, len(btfVars))
+			for _, btfVar := range btfVars {
+				vars = append(vars, VarSecinfo{
+					Offset: btfVar.Offset,
+					Size:   btfVar.Size,
+				})
+			}
+			for i := range vars {
+				fixup(btfVars[i].Type, kindVar, &vars[i].Type)
+			}
+			typ = &Datasec{id, name, raw.SizeType, vars}
+
+		default:
+			return nil, nil, fmt.Errorf("type id %d: unknown kind: %v", id, raw.Kind())
+		}
+
+		types = append(types, typ)
+
+		if named, ok := typ.(namedType); ok {
+			if name := essentialName(named.name()); name != "" {
+				namedTypes[name] = append(namedTypes[name], named)
+			}
+		}
+	}
+
+	for _, fixup := range fixups {
+		i := int(fixup.id)
+		if i >= len(types) {
+			return nil, nil, fmt.Errorf("reference to invalid type id: %d", fixup.id)
+		}
+
+		// Default void (id 0) to unknown
+		rawKind := kindUnknown
+		if i > 0 {
+			rawKind = rawTypes[i-1].Kind()
+		}
+
+		if expected := fixup.expectedKind; expected != kindUnknown && rawKind != expected {
+			return nil, nil, fmt.Errorf("expected type id %d to have kind %s, found %s", fixup.id, expected, rawKind)
+		}
+
+		*fixup.typ = types[i]
+	}
+
+	return types, namedTypes, nil
+}
+
+// essentialName returns name without a ___ suffix.
+func essentialName(name string) string {
+	lastIdx := strings.LastIndex(name, "___")
+	if lastIdx > 0 {
+		return name[:lastIdx]
+	}
+	return name
+}