chore: update cgroups and ttrpc versions

- update github.com/containerd/cgroups to v1.1.0
- update github.com/containerd/ttrpc to v1.2.1

Signed-off-by: Akhil Mohan <akhilerm@gmail.com>

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

@@ -0,0 +1,897 @@
+package btf
+
+import (
+	"bufio"
+	"bytes"
+	"debug/elf"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"math"
+	"os"
+	"reflect"
+
+	"github.com/cilium/ebpf/internal"
+	"github.com/cilium/ebpf/internal/sys"
+	"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")
+)
+
+// ID represents the unique ID of a BTF object.
+type ID = sys.BTFID
+
+// Spec represents decoded BTF.
+type Spec struct {
+	// Data from .BTF.
+	rawTypes []rawType
+	strings  *stringTable
+
+	// All types contained by the spec. For the base type, the position of
+	// a type in the slice is its ID.
+	types types
+
+	// Type IDs indexed by type.
+	typeIDs map[Type]TypeID
+
+	// Types indexed by essential name.
+	// Includes all struct flavors and types with the same name.
+	namedTypes map[essentialName][]Type
+
+	byteOrder binary.ByteOrder
+}
+
+type btfHeader struct {
+	Magic   uint16
+	Version uint8
+	Flags   uint8
+	HdrLen  uint32
+
+	TypeOff   uint32
+	TypeLen   uint32
+	StringOff uint32
+	StringLen uint32
+}
+
+// typeStart returns the offset from the beginning of the .BTF section
+// to the start of its type entries.
+func (h *btfHeader) typeStart() int64 {
+	return int64(h.HdrLen + h.TypeOff)
+}
+
+// stringStart returns the offset from the beginning of the .BTF section
+// to the start of its string table.
+func (h *btfHeader) stringStart() int64 {
+	return int64(h.HdrLen + h.StringOff)
+}
+
+// LoadSpec opens file and calls LoadSpecFromReader on it.
+func LoadSpec(file string) (*Spec, error) {
+	fh, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+	defer fh.Close()
+
+	return LoadSpecFromReader(fh)
+}
+
+// LoadSpecFromReader reads from an ELF or a raw BTF blob.
+//
+// Returns ErrNotFound if reading from an ELF which contains no BTF. ExtInfos
+// may be nil.
+func LoadSpecFromReader(rd io.ReaderAt) (*Spec, error) {
+	file, err := internal.NewSafeELFFile(rd)
+	if err != nil {
+		if bo := guessRawBTFByteOrder(rd); bo != nil {
+			// Try to parse a naked BTF blob. This will return an error if
+			// we encounter a Datasec, since we can't fix it up.
+			spec, err := loadRawSpec(io.NewSectionReader(rd, 0, math.MaxInt64), bo, nil, nil)
+			return spec, err
+		}
+
+		return nil, err
+	}
+
+	return loadSpecFromELF(file)
+}
+
+// LoadSpecAndExtInfosFromReader reads from an ELF.
+//
+// ExtInfos may be nil if the ELF doesn't contain section metadta.
+// Returns ErrNotFound if the ELF contains no BTF.
+func LoadSpecAndExtInfosFromReader(rd io.ReaderAt) (*Spec, *ExtInfos, error) {
+	file, err := internal.NewSafeELFFile(rd)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	spec, err := loadSpecFromELF(file)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	extInfos, err := loadExtInfosFromELF(file, spec.types, spec.strings)
+	if err != nil && !errors.Is(err, ErrNotFound) {
+		return nil, nil, err
+	}
+
+	return spec, extInfos, nil
+}
+
+// variableOffsets extracts all symbols offsets from an ELF and indexes them by
+// section and variable name.
+//
+// References to variables in BTF data sections carry unsigned 32-bit offsets.
+// Some ELF symbols (e.g. in vmlinux) may point to virtual memory that is well
+// beyond this range. Since these symbols cannot be described by BTF info,
+// ignore them here.
+func variableOffsets(file *internal.SafeELFFile) (map[variable]uint32, error) {
+	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 symbol.Value > math.MaxUint32 {
+			// VarSecinfo offset is u32, cannot reference symbols in higher regions.
+			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
+		variableOffsets[variable{secName, symbol.Name}] = uint32(symbol.Value)
+	}
+
+	return variableOffsets, nil
+}
+
+func loadSpecFromELF(file *internal.SafeELFFile) (*Spec, error) {
+	var (
+		btfSection   *elf.Section
+		sectionSizes = make(map[string]uint32)
+	)
+
+	for _, sec := range file.Sections {
+		switch sec.Name {
+		case ".BTF":
+			btfSection = sec
+		default:
+			if sec.Type != elf.SHT_PROGBITS && sec.Type != elf.SHT_NOBITS {
+				break
+			}
+
+			if sec.Size > math.MaxUint32 {
+				return nil, fmt.Errorf("section %s exceeds maximum size", sec.Name)
+			}
+
+			sectionSizes[sec.Name] = uint32(sec.Size)
+		}
+	}
+
+	if btfSection == nil {
+		return nil, fmt.Errorf("btf: %w", ErrNotFound)
+	}
+
+	vars, err := variableOffsets(file)
+	if err != nil {
+		return nil, err
+	}
+
+	if btfSection.ReaderAt == nil {
+		return nil, fmt.Errorf("compressed BTF is not supported")
+	}
+
+	rawTypes, rawStrings, err := parseBTF(btfSection.ReaderAt, file.ByteOrder, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	err = fixupDatasec(rawTypes, rawStrings, sectionSizes, vars)
+	if err != nil {
+		return nil, err
+	}
+
+	return inflateSpec(rawTypes, rawStrings, file.ByteOrder, nil)
+}
+
+func loadRawSpec(btf io.ReaderAt, bo binary.ByteOrder,
+	baseTypes types, baseStrings *stringTable) (*Spec, error) {
+
+	rawTypes, rawStrings, err := parseBTF(btf, bo, baseStrings)
+	if err != nil {
+		return nil, err
+	}
+
+	return inflateSpec(rawTypes, rawStrings, bo, baseTypes)
+}
+
+func inflateSpec(rawTypes []rawType, rawStrings *stringTable, bo binary.ByteOrder,
+	baseTypes types) (*Spec, error) {
+
+	types, err := inflateRawTypes(rawTypes, baseTypes, rawStrings)
+	if err != nil {
+		return nil, err
+	}
+
+	typeIDs, typesByName := indexTypes(types, TypeID(len(baseTypes)))
+
+	return &Spec{
+		rawTypes:   rawTypes,
+		namedTypes: typesByName,
+		typeIDs:    typeIDs,
+		types:      types,
+		strings:    rawStrings,
+		byteOrder:  bo,
+	}, nil
+}
+
+func indexTypes(types []Type, typeIDOffset TypeID) (map[Type]TypeID, map[essentialName][]Type) {
+	namedTypes := 0
+	for _, typ := range types {
+		if typ.TypeName() != "" {
+			// Do a pre-pass to figure out how big types by name has to be.
+			// Most types have unique names, so it's OK to ignore essentialName
+			// here.
+			namedTypes++
+		}
+	}
+
+	typeIDs := make(map[Type]TypeID, len(types))
+	typesByName := make(map[essentialName][]Type, namedTypes)
+
+	for i, typ := range types {
+		if name := newEssentialName(typ.TypeName()); name != "" {
+			typesByName[name] = append(typesByName[name], typ)
+		}
+		typeIDs[typ] = TypeID(i) + typeIDOffset
+	}
+
+	return typeIDs, typesByName
+}
+
+// LoadKernelSpec returns the current kernel's BTF information.
+//
+// Defaults to /sys/kernel/btf/vmlinux and falls back to scanning the file system
+// for vmlinux ELFs. Returns an error wrapping ErrNotSupported if BTF is not enabled.
+func LoadKernelSpec() (*Spec, error) {
+	fh, err := os.Open("/sys/kernel/btf/vmlinux")
+	if err == nil {
+		defer fh.Close()
+
+		return loadRawSpec(fh, internal.NativeEndian, nil, nil)
+	}
+
+	file, err := findVMLinux()
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	return loadSpecFromELF(file)
+}
+
+// findVMLinux scans multiple well-known paths for vmlinux kernel images.
+func findVMLinux() (*internal.SafeELFFile, error) {
+	release, err := internal.KernelRelease()
+	if err != nil {
+		return nil, err
+	}
+
+	// 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 {
+		file, err := internal.OpenSafeELFFile(fmt.Sprintf(loc, release))
+		if errors.Is(err, os.ErrNotExist) {
+			continue
+		}
+		return file, err
+	}
+
+	return nil, fmt.Errorf("no BTF found for kernel version %s: %w", release, internal.ErrNotSupported)
+}
+
+// parseBTFHeader parses the header of the .BTF section.
+func parseBTFHeader(r io.Reader, bo binary.ByteOrder) (*btfHeader, error) {
+	var header btfHeader
+	if err := binary.Read(r, bo, &header); err != nil {
+		return nil, fmt.Errorf("can't read header: %v", err)
+	}
+
+	if header.Magic != btfMagic {
+		return nil, fmt.Errorf("incorrect magic value %v", header.Magic)
+	}
+
+	if header.Version != 1 {
+		return nil, fmt.Errorf("unexpected version %v", header.Version)
+	}
+
+	if header.Flags != 0 {
+		return nil, fmt.Errorf("unsupported flags %v", header.Flags)
+	}
+
+	remainder := int64(header.HdrLen) - int64(binary.Size(&header))
+	if remainder < 0 {
+		return nil, errors.New("header length shorter than btfHeader size")
+	}
+
+	if _, err := io.CopyN(internal.DiscardZeroes{}, r, remainder); err != nil {
+		return nil, fmt.Errorf("header padding: %v", err)
+	}
+
+	return &header, nil
+}
+
+func guessRawBTFByteOrder(r io.ReaderAt) binary.ByteOrder {
+	buf := new(bufio.Reader)
+	for _, bo := range []binary.ByteOrder{
+		binary.LittleEndian,
+		binary.BigEndian,
+	} {
+		buf.Reset(io.NewSectionReader(r, 0, math.MaxInt64))
+		if _, err := parseBTFHeader(buf, bo); err == nil {
+			return bo
+		}
+	}
+
+	return nil
+}
+
+// parseBTF reads a .BTF section into memory and parses it into a list of
+// raw types and a string table.
+func parseBTF(btf io.ReaderAt, bo binary.ByteOrder, baseStrings *stringTable) ([]rawType, *stringTable, error) {
+	buf := internal.NewBufferedSectionReader(btf, 0, math.MaxInt64)
+	header, err := parseBTFHeader(buf, bo)
+	if err != nil {
+		return nil, nil, fmt.Errorf("parsing .BTF header: %v", err)
+	}
+
+	rawStrings, err := readStringTable(io.NewSectionReader(btf, header.stringStart(), int64(header.StringLen)),
+		baseStrings)
+	if err != nil {
+		return nil, nil, fmt.Errorf("can't read type names: %w", err)
+	}
+
+	buf.Reset(io.NewSectionReader(btf, header.typeStart(), int64(header.TypeLen)))
+	rawTypes, err := readTypes(buf, bo, header.TypeLen)
+	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
+}
+
+// Copy creates a copy of Spec.
+func (s *Spec) Copy() *Spec {
+	types := copyTypes(s.types, nil)
+
+	typeIDOffset := TypeID(0)
+	if len(s.types) != 0 {
+		typeIDOffset = s.typeIDs[s.types[0]]
+	}
+	typeIDs, typesByName := indexTypes(types, typeIDOffset)
+
+	// NB: Other parts of spec are not copied since they are immutable.
+	return &Spec{
+		s.rawTypes,
+		s.strings,
+		types,
+		typeIDs,
+		typesByName,
+		s.byteOrder,
+	}
+}
+
+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(StaticFunc)
+		}
+
+		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.
+	stringsLen := s.strings.Length()
+	buf.Grow(stringsLen)
+	if err := s.strings.Marshal(&buf); err != nil {
+		return nil, err
+	}
+
+	// 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(stringsLen),
+	}
+
+	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
+}
+
+// TypeByID returns the BTF Type with the given type ID.
+//
+// Returns an error wrapping ErrNotFound if a Type with the given ID
+// does not exist in the Spec.
+func (s *Spec) TypeByID(id TypeID) (Type, error) {
+	return s.types.ByID(id)
+}
+
+// TypeID returns the ID for a given Type.
+//
+// Returns an error wrapping ErrNoFound if the type isn't part of the Spec.
+func (s *Spec) TypeID(typ Type) (TypeID, error) {
+	if _, ok := typ.(*Void); ok {
+		// Equality is weird for void, since it is a zero sized type.
+		return 0, nil
+	}
+
+	id, ok := s.typeIDs[typ]
+	if !ok {
+		return 0, fmt.Errorf("no ID for type %s: %w", typ, ErrNotFound)
+	}
+
+	return id, nil
+}
+
+// AnyTypesByName returns a list of BTF Types with the given name.
+//
+// If the BTF blob describes multiple compilation units like vmlinux, multiple
+// Types with the same name and kind can exist, but might not describe the same
+// data structure.
+//
+// Returns an error wrapping ErrNotFound if no matching Type exists in the Spec.
+func (s *Spec) AnyTypesByName(name string) ([]Type, error) {
+	types := s.namedTypes[newEssentialName(name)]
+	if len(types) == 0 {
+		return nil, fmt.Errorf("type name %s: %w", name, ErrNotFound)
+	}
+
+	// Return a copy to prevent changes to namedTypes.
+	result := make([]Type, 0, len(types))
+	for _, t := range types {
+		// Match against the full name, not just the essential one
+		// in case the type being looked up is a struct flavor.
+		if t.TypeName() == name {
+			result = append(result, t)
+		}
+	}
+	return result, nil
+}
+
+// AnyTypeByName returns a Type with the given name.
+//
+// Returns an error if multiple types of that name exist.
+func (s *Spec) AnyTypeByName(name string) (Type, error) {
+	types, err := s.AnyTypesByName(name)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(types) > 1 {
+		return nil, fmt.Errorf("found multiple types: %v", types)
+	}
+
+	return types[0], nil
+}
+
+// TypeByName searches for a Type with a specific name. Since multiple
+// Types with the same name can exist, the parameter typ is taken to
+// narrow down the search in case of a clash.
+//
+// typ must be a non-nil pointer to an implementation of a Type.
+// On success, the address of the found Type will be copied to typ.
+//
+// Returns an error wrapping ErrNotFound if no matching
+// Type exists in the Spec. If multiple candidates are found,
+// an error is returned.
+func (s *Spec) TypeByName(name string, typ interface{}) error {
+	typValue := reflect.ValueOf(typ)
+	if typValue.Kind() != reflect.Ptr {
+		return fmt.Errorf("%T is not a pointer", typ)
+	}
+
+	typPtr := typValue.Elem()
+	if !typPtr.CanSet() {
+		return fmt.Errorf("%T cannot be set", typ)
+	}
+
+	wanted := typPtr.Type()
+	if !wanted.AssignableTo(reflect.TypeOf((*Type)(nil)).Elem()) {
+		return fmt.Errorf("%T does not satisfy Type interface", typ)
+	}
+
+	types, err := s.AnyTypesByName(name)
+	if err != nil {
+		return err
+	}
+
+	var candidate Type
+	for _, typ := range types {
+		if reflect.TypeOf(typ) != wanted {
+			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)
+	}
+
+	typPtr.Set(reflect.ValueOf(candidate))
+
+	return nil
+}
+
+// LoadSplitSpecFromReader loads split BTF from a reader.
+//
+// Types from base are used to resolve references in the split BTF.
+// The returned Spec only contains types from the split BTF, not from the base.
+func LoadSplitSpecFromReader(r io.ReaderAt, base *Spec) (*Spec, error) {
+	return loadRawSpec(r, internal.NativeEndian, base.types, base.strings)
+}
+
+// TypesIterator iterates over types of a given spec.
+type TypesIterator struct {
+	spec  *Spec
+	index int
+	// The last visited type in the spec.
+	Type Type
+}
+
+// Iterate returns the types iterator.
+func (s *Spec) Iterate() *TypesIterator {
+	return &TypesIterator{spec: s, index: 0}
+}
+
+// Next returns true as long as there are any remaining types.
+func (iter *TypesIterator) Next() bool {
+	if len(iter.spec.types) <= iter.index {
+		return false
+	}
+
+	iter.Type = iter.spec.types[iter.index]
+	iter.index++
+	return true
+}
+
+// Handle is a reference to BTF loaded into the kernel.
+type Handle struct {
+	fd *sys.FD
+
+	// Size of the raw BTF in bytes.
+	size uint32
+}
+
+// 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 := &sys.BtfLoadAttr{
+		Btf:     sys.NewSlicePointer(btf),
+		BtfSize: uint32(len(btf)),
+	}
+
+	fd, err := sys.BtfLoad(attr)
+	if err != nil {
+		logBuf := make([]byte, 64*1024)
+		attr.BtfLogBuf = sys.NewSlicePointer(logBuf)
+		attr.BtfLogSize = uint32(len(logBuf))
+		attr.BtfLogLevel = 1
+		// NB: The syscall will never return ENOSPC as of 5.18-rc4.
+		_, _ = sys.BtfLoad(attr)
+		return nil, internal.ErrorWithLog(err, logBuf)
+	}
+
+	return &Handle{fd, attr.BtfSize}, nil
+}
+
+// NewHandleFromID returns the BTF handle for a given id.
+//
+// Prefer calling [ebpf.Program.Handle] or [ebpf.Map.Handle] if possible.
+//
+// Returns ErrNotExist, if there is no BTF with the given id.
+//
+// Requires CAP_SYS_ADMIN.
+func NewHandleFromID(id ID) (*Handle, error) {
+	fd, err := sys.BtfGetFdById(&sys.BtfGetFdByIdAttr{
+		Id: uint32(id),
+	})
+	if err != nil {
+		return nil, fmt.Errorf("get FD for ID %d: %w", id, err)
+	}
+
+	info, err := newHandleInfoFromFD(fd)
+	if err != nil {
+		_ = fd.Close()
+		return nil, err
+	}
+
+	return &Handle{fd, info.size}, nil
+}
+
+// Spec parses the kernel BTF into Go types.
+//
+// base is used to decode split BTF and may be nil.
+func (h *Handle) Spec(base *Spec) (*Spec, error) {
+	var btfInfo sys.BtfInfo
+	btfBuffer := make([]byte, h.size)
+	btfInfo.Btf, btfInfo.BtfSize = sys.NewSlicePointerLen(btfBuffer)
+
+	if err := sys.ObjInfo(h.fd, &btfInfo); err != nil {
+		return nil, err
+	}
+
+	var baseTypes types
+	var baseStrings *stringTable
+	if base != nil {
+		baseTypes = base.types
+		baseStrings = base.strings
+	}
+
+	return loadRawSpec(bytes.NewReader(btfBuffer), internal.NativeEndian, baseTypes, baseStrings)
+}
+
+// Close destroys the handle.
+//
+// Subsequent calls to FD will return an invalid value.
+func (h *Handle) Close() error {
+	if h == nil {
+		return nil
+	}
+
+	return h.fd.Close()
+}
+
+// FD returns the file descriptor for the handle.
+func (h *Handle) FD() int {
+	return h.fd.Int()
+}
+
+// Info returns metadata about the handle.
+func (h *Handle) Info() (*HandleInfo, error) {
+	return newHandleInfoFromFD(h.fd)
+}
+
+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 := sys.BtfLoad(&sys.BtfLoadAttr{
+		Btf:     sys.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(GlobalFunc)
+
+	btf := marshalBTF(&types, strings, internal.NativeEndian)
+
+	fd, err := sys.BtfLoad(&sys.BtfLoadAttr{
+		Btf:     sys.NewSlicePointer(btf),
+		BtfSize: uint32(len(btf)),
+	})
+	if errors.Is(err, unix.EINVAL) {
+		return internal.ErrNotSupported
+	}
+	if err != nil {
+		return err
+	}
+
+	fd.Close()
+	return nil
+})

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

@@ -0,0 +1,343 @@
+package btf
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+//go:generate stringer -linecomment -output=btf_types_string.go -type=FuncLinkage,VarLinkage
+
+// 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
+	// Added ~5.13
+	kindFloat
+)
+
+// FuncLinkage describes BTF function linkage metadata.
+type FuncLinkage int
+
+// Equivalent of enum btf_func_linkage.
+const (
+	StaticFunc FuncLinkage = iota // static
+	GlobalFunc                    // global
+	ExternFunc                    // extern
+)
+
+// VarLinkage describes BTF variable linkage metadata.
+type VarLinkage int
+
+const (
+	StaticVar VarLinkage = iota // static
+	GlobalVar                   // global
+	ExternVar                   // extern
+)
+
+const (
+	btfTypeKindShift     = 24
+	btfTypeKindLen       = 5
+	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 24-28: kind (e.g. int, ptr, array...etc)
+	 * bits 29-30: 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"
+	case kindFloat:
+		return "Float"
+	default:
+		return fmt.Sprintf("Unknown (%d)", k)
+	}
+}
+
+func mask(len uint32) uint32 {
+	return (1 << len) - 1
+}
+
+func readBits(value, len, shift uint32) uint32 {
+	return (value >> shift) & mask(len)
+}
+
+func writeBits(value, len, shift, new uint32) uint32 {
+	value &^= mask(len) << shift
+	value |= (new & mask(len)) << shift
+	return value
+}
+
+func (bt *btfType) info(len, shift uint32) uint32 {
+	return readBits(bt.Info, len, shift)
+}
+
+func (bt *btfType) setInfo(value, len, shift uint32) {
+	bt.Info = writeBits(bt.Info, len, shift, value)
+}
+
+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() FuncLinkage {
+	return FuncLinkage(bt.info(btfTypeVlenMask, btfTypeVlenShift))
+}
+
+func (bt *btfType) SetLinkage(linkage FuncLinkage) {
+	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
+}
+
+func (bt *btfType) SetSize(size uint32) {
+	bt.SizeType = size
+}
+
+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)
+}
+
+// btfInt encodes additional data for integers.
+//
+//    ? ? ? ? e e e e o o o o o o o o ? ? ? ? ? ? ? ? b b b b b b b b
+//    ? = undefined
+//    e = encoding
+//    o = offset (bitfields?)
+//    b = bits (bitfields)
+type btfInt struct {
+	Raw uint32
+}
+
+const (
+	btfIntEncodingLen   = 4
+	btfIntEncodingShift = 24
+	btfIntOffsetLen     = 8
+	btfIntOffsetShift   = 16
+	btfIntBitsLen       = 8
+	btfIntBitsShift     = 0
+)
+
+func (bi btfInt) Encoding() IntEncoding {
+	return IntEncoding(readBits(bi.Raw, btfIntEncodingLen, btfIntEncodingShift))
+}
+
+func (bi *btfInt) SetEncoding(e IntEncoding) {
+	bi.Raw = writeBits(uint32(bi.Raw), btfIntEncodingLen, btfIntEncodingShift, uint32(e))
+}
+
+func (bi btfInt) Offset() Bits {
+	return Bits(readBits(bi.Raw, btfIntOffsetLen, btfIntOffsetShift))
+}
+
+func (bi *btfInt) SetOffset(offset uint32) {
+	bi.Raw = writeBits(bi.Raw, btfIntOffsetLen, btfIntOffsetShift, offset)
+}
+
+func (bi btfInt) Bits() Bits {
+	return Bits(readBits(bi.Raw, btfIntBitsLen, btfIntBitsShift))
+}
+
+func (bi *btfInt) SetBits(bits byte) {
+	bi.Raw = writeBits(bi.Raw, btfIntBitsLen, btfIntBitsShift, uint32(bits))
+}
+
+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, typeLen uint32) ([]rawType, error) {
+	var header btfType
+	// because of the interleaving between types and struct members it is difficult to
+	// precompute the numbers of raw types this will parse
+	// this "guess" is a good first estimation
+	sizeOfbtfType := uintptr(binary.Size(btfType{}))
+	tyMaxCount := uintptr(typeLen) / sizeOfbtfType / 2
+	types := make([]rawType, 0, tyMaxCount)
+
+	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(btfInt)
+		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())
+		case kindFloat:
+		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})
+	}
+}

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

@@ -0,0 +1,44 @@
+// Code generated by "stringer -linecomment -output=btf_types_string.go -type=FuncLinkage,VarLinkage"; DO NOT EDIT.
+
+package btf
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[StaticFunc-0]
+	_ = x[GlobalFunc-1]
+	_ = x[ExternFunc-2]
+}
+
+const _FuncLinkage_name = "staticglobalextern"
+
+var _FuncLinkage_index = [...]uint8{0, 6, 12, 18}
+
+func (i FuncLinkage) String() string {
+	if i < 0 || i >= FuncLinkage(len(_FuncLinkage_index)-1) {
+		return "FuncLinkage(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _FuncLinkage_name[_FuncLinkage_index[i]:_FuncLinkage_index[i+1]]
+}
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[StaticVar-0]
+	_ = x[GlobalVar-1]
+	_ = x[ExternVar-2]
+}
+
+const _VarLinkage_name = "staticglobalextern"
+
+var _VarLinkage_index = [...]uint8{0, 6, 12, 18}
+
+func (i VarLinkage) String() string {
+	if i < 0 || i >= VarLinkage(len(_VarLinkage_index)-1) {
+		return "VarLinkage(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _VarLinkage_name[_VarLinkage_index[i]:_VarLinkage_index[i+1]]
+}

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

@@ -0,0 +1,972 @@
+package btf
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"math"
+	"reflect"
+	"strconv"
+	"strings"
+
+	"github.com/cilium/ebpf/asm"
+)
+
+// Code in this file is derived from libbpf, which is available under a BSD
+// 2-Clause license.
+
+// COREFixup is the result of computing a CO-RE relocation for a target.
+type COREFixup struct {
+	kind   coreKind
+	local  uint32
+	target uint32
+	// True if there is no valid fixup. The instruction is replaced with an
+	// invalid dummy.
+	poison bool
+	// True if the validation of the local value should be skipped. Used by
+	// some kinds of bitfield relocations.
+	skipLocalValidation bool
+}
+
+func (f *COREFixup) equal(other COREFixup) bool {
+	return f.local == other.local && f.target == other.target
+}
+
+func (f *COREFixup) String() string {
+	if f.poison {
+		return fmt.Sprintf("%s=poison", f.kind)
+	}
+	return fmt.Sprintf("%s=%d->%d", f.kind, f.local, f.target)
+}
+
+func (f *COREFixup) Apply(ins *asm.Instruction) error {
+	if f.poison {
+		const badRelo = 0xbad2310
+
+		*ins = asm.BuiltinFunc(badRelo).Call()
+		return nil
+	}
+
+	switch class := ins.OpCode.Class(); class {
+	case asm.LdXClass, asm.StClass, asm.StXClass:
+		if want := int16(f.local); !f.skipLocalValidation && want != ins.Offset {
+			return fmt.Errorf("invalid offset %d, expected %d", ins.Offset, f.local)
+		}
+
+		if f.target > math.MaxInt16 {
+			return fmt.Errorf("offset %d exceeds MaxInt16", f.target)
+		}
+
+		ins.Offset = int16(f.target)
+
+	case asm.LdClass:
+		if !ins.IsConstantLoad(asm.DWord) {
+			return fmt.Errorf("not a dword-sized immediate load")
+		}
+
+		if want := int64(f.local); !f.skipLocalValidation && want != ins.Constant {
+			return fmt.Errorf("invalid immediate %d, expected %d (fixup: %v)", ins.Constant, want, f)
+		}
+
+		ins.Constant = int64(f.target)
+
+	case asm.ALUClass:
+		if ins.OpCode.ALUOp() == asm.Swap {
+			return fmt.Errorf("relocation against swap")
+		}
+
+		fallthrough
+
+	case asm.ALU64Class:
+		if src := ins.OpCode.Source(); src != asm.ImmSource {
+			return fmt.Errorf("invalid source %s", src)
+		}
+
+		if want := int64(f.local); !f.skipLocalValidation && want != ins.Constant {
+			return fmt.Errorf("invalid immediate %d, expected %d (fixup: %v, kind: %v, ins: %v)", ins.Constant, want, f, f.kind, ins)
+		}
+
+		if f.target > math.MaxInt32 {
+			return fmt.Errorf("immediate %d exceeds MaxInt32", f.target)
+		}
+
+		ins.Constant = int64(f.target)
+
+	default:
+		return fmt.Errorf("invalid class %s", class)
+	}
+
+	return nil
+}
+
+func (f COREFixup) isNonExistant() bool {
+	return f.kind.checksForExistence() && f.target == 0
+}
+
+// coreKind is the type of CO-RE relocation as specified in BPF source code.
+type coreKind uint32
+
+const (
+	reloFieldByteOffset coreKind = 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 coreKind) checksForExistence() bool {
+	return k == reloEnumvalExists || k == reloTypeExists || k == reloFieldExists
+}
+
+func (k coreKind) 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"
+	}
+}
+
+// CORERelocate calculates the difference in types between local and target.
+//
+// Returns a list of fixups which can be applied to instructions to make them
+// match the target type(s).
+//
+// Fixups are returned in the order of relos, e.g. fixup[i] is the solution
+// for relos[i].
+func CORERelocate(local, target *Spec, relos []*CORERelocation) ([]COREFixup, error) {
+	if local.byteOrder != target.byteOrder {
+		return nil, fmt.Errorf("can't relocate %s against %s", local.byteOrder, target.byteOrder)
+	}
+
+	type reloGroup struct {
+		relos []*CORERelocation
+		// Position of each relocation in relos.
+		indices []int
+	}
+
+	// Split relocations into per Type lists.
+	relosByType := make(map[Type]*reloGroup)
+	result := make([]COREFixup, len(relos))
+	for i, relo := range relos {
+		if relo.kind == reloTypeIDLocal {
+			// Filtering out reloTypeIDLocal here makes our lives a lot easier
+			// down the line, since it doesn't have a target at all.
+			if len(relo.accessor) > 1 || relo.accessor[0] != 0 {
+				return nil, fmt.Errorf("%s: unexpected accessor %v", relo.kind, relo.accessor)
+			}
+
+			id, err := local.TypeID(relo.typ)
+			if err != nil {
+				return nil, fmt.Errorf("%s: %w", relo.kind, err)
+			}
+
+			result[i] = COREFixup{
+				kind:   relo.kind,
+				local:  uint32(id),
+				target: uint32(id),
+			}
+			continue
+		}
+
+		group, ok := relosByType[relo.typ]
+		if !ok {
+			group = &reloGroup{}
+			relosByType[relo.typ] = group
+		}
+		group.relos = append(group.relos, relo)
+		group.indices = append(group.indices, i)
+	}
+
+	for localType, group := range relosByType {
+		localTypeName := localType.TypeName()
+		if localTypeName == "" {
+			return nil, fmt.Errorf("relocate unnamed or anonymous type %s: %w", localType, ErrNotSupported)
+		}
+
+		targets := target.namedTypes[newEssentialName(localTypeName)]
+		fixups, err := coreCalculateFixups(local, target, localType, targets, group.relos)
+		if err != nil {
+			return nil, fmt.Errorf("relocate %s: %w", localType, err)
+		}
+
+		for j, index := range group.indices {
+			result[index] = fixups[j]
+		}
+	}
+
+	return result, nil
+}
+
+var errAmbiguousRelocation = errors.New("ambiguous relocation")
+var errImpossibleRelocation = errors.New("impossible relocation")
+
+// coreCalculateFixups calculates the fixups for the given relocations using
+// the "best" target.
+//
+// The best target is determined by scoring: the less poisoning we have to do
+// the better the target is.
+func coreCalculateFixups(localSpec, targetSpec *Spec, local Type, targets []Type, relos []*CORERelocation) ([]COREFixup, error) {
+	localID, err := localSpec.TypeID(local)
+	if err != nil {
+		return nil, fmt.Errorf("local type ID: %w", err)
+	}
+	local = Copy(local, UnderlyingType)
+
+	bestScore := len(relos)
+	var bestFixups []COREFixup
+	for i := range targets {
+		targetID, err := targetSpec.TypeID(targets[i])
+		if err != nil {
+			return nil, fmt.Errorf("target type ID: %w", err)
+		}
+		target := Copy(targets[i], UnderlyingType)
+
+		score := 0 // lower is better
+		fixups := make([]COREFixup, 0, len(relos))
+		for _, relo := range relos {
+			fixup, err := coreCalculateFixup(localSpec.byteOrder, local, localID, target, targetID, relo)
+			if err != nil {
+				return nil, fmt.Errorf("target %s: %w", target, err)
+			}
+			if fixup.poison || fixup.isNonExistant() {
+				score++
+			}
+			fixups = append(fixups, fixup)
+		}
+
+		if score > bestScore {
+			// We have a better target already, ignore this one.
+			continue
+		}
+
+		if score < bestScore {
+			// This is the best target yet, use it.
+			bestScore = score
+			bestFixups = fixups
+			continue
+		}
+
+		// Some other target has the same score as the current one. Make sure
+		// the fixups agree with each other.
+		for i, fixup := range bestFixups {
+			if !fixup.equal(fixups[i]) {
+				return nil, fmt.Errorf("%s: multiple types match: %w", fixup.kind, errAmbiguousRelocation)
+			}
+		}
+	}
+
+	if bestFixups == nil {
+		// Nothing at all matched, probably because there are no suitable
+		// targets at all.
+		//
+		// Poison everything except checksForExistence.
+		bestFixups = make([]COREFixup, len(relos))
+		for i, relo := range relos {
+			if relo.kind.checksForExistence() {
+				bestFixups[i] = COREFixup{kind: relo.kind, local: 1, target: 0}
+			} else {
+				bestFixups[i] = COREFixup{kind: relo.kind, poison: true}
+			}
+		}
+	}
+
+	return bestFixups, nil
+}
+
+// coreCalculateFixup calculates the fixup for a single local type, target type
+// and relocation.
+func coreCalculateFixup(byteOrder binary.ByteOrder, local Type, localID TypeID, target Type, targetID TypeID, relo *CORERelocation) (COREFixup, error) {
+	fixup := func(local, target uint32) (COREFixup, error) {
+		return COREFixup{kind: relo.kind, local: local, target: target}, nil
+	}
+	fixupWithoutValidation := func(local, target uint32) (COREFixup, error) {
+		return COREFixup{kind: relo.kind, local: local, target: target, skipLocalValidation: true}, nil
+	}
+	poison := func() (COREFixup, error) {
+		if relo.kind.checksForExistence() {
+			return fixup(1, 0)
+		}
+		return COREFixup{kind: relo.kind, poison: true}, nil
+	}
+	zero := COREFixup{}
+
+	switch relo.kind {
+	case reloTypeIDTarget, reloTypeSize, reloTypeExists:
+		if len(relo.accessor) > 1 || relo.accessor[0] != 0 {
+			return zero, fmt.Errorf("%s: unexpected accessor %v", relo.kind, relo.accessor)
+		}
+
+		err := coreAreTypesCompatible(local, target)
+		if errors.Is(err, errImpossibleRelocation) {
+			return poison()
+		}
+		if err != nil {
+			return zero, fmt.Errorf("relocation %s: %w", relo.kind, err)
+		}
+
+		switch relo.kind {
+		case reloTypeExists:
+			return fixup(1, 1)
+
+		case reloTypeIDTarget:
+			return fixup(uint32(localID), uint32(targetID))
+
+		case reloTypeSize:
+			localSize, err := Sizeof(local)
+			if err != nil {
+				return zero, err
+			}
+
+			targetSize, err := Sizeof(target)
+			if err != nil {
+				return zero, err
+			}
+
+			return fixup(uint32(localSize), uint32(targetSize))
+		}
+
+	case reloEnumvalValue, reloEnumvalExists:
+		localValue, targetValue, err := coreFindEnumValue(local, relo.accessor, target)
+		if errors.Is(err, errImpossibleRelocation) {
+			return poison()
+		}
+		if err != nil {
+			return zero, fmt.Errorf("relocation %s: %w", relo.kind, err)
+		}
+
+		switch relo.kind {
+		case reloEnumvalExists:
+			return fixup(1, 1)
+
+		case reloEnumvalValue:
+			return fixup(uint32(localValue.Value), uint32(targetValue.Value))
+		}
+
+	case reloFieldSigned:
+		switch local.(type) {
+		case *Enum:
+			return fixup(1, 1)
+		case *Int:
+			return fixup(
+				uint32(local.(*Int).Encoding&Signed),
+				uint32(target.(*Int).Encoding&Signed),
+			)
+		default:
+			return fixupWithoutValidation(0, 0)
+		}
+
+	case reloFieldByteOffset, reloFieldByteSize, reloFieldExists, reloFieldLShiftU64, reloFieldRShiftU64:
+		if _, ok := target.(*Fwd); ok {
+			// We can't relocate fields using a forward declaration, so
+			// skip it. If a non-forward declaration is present in the BTF
+			// we'll find it in one of the other iterations.
+			return poison()
+		}
+
+		localField, targetField, err := coreFindField(local, relo.accessor, target)
+		if errors.Is(err, errImpossibleRelocation) {
+			return poison()
+		}
+		if err != nil {
+			return zero, fmt.Errorf("target %s: %w", target, err)
+		}
+
+		maybeSkipValidation := func(f COREFixup, err error) (COREFixup, error) {
+			f.skipLocalValidation = localField.bitfieldSize > 0
+			return f, err
+		}
+
+		switch relo.kind {
+		case reloFieldExists:
+			return fixup(1, 1)
+
+		case reloFieldByteOffset:
+			return maybeSkipValidation(fixup(localField.offset, targetField.offset))
+
+		case reloFieldByteSize:
+			localSize, err := Sizeof(localField.Type)
+			if err != nil {
+				return zero, err
+			}
+
+			targetSize, err := Sizeof(targetField.Type)
+			if err != nil {
+				return zero, err
+			}
+			return maybeSkipValidation(fixup(uint32(localSize), uint32(targetSize)))
+
+		case reloFieldLShiftU64:
+			var target uint32
+			if byteOrder == binary.LittleEndian {
+				targetSize, err := targetField.sizeBits()
+				if err != nil {
+					return zero, err
+				}
+
+				target = uint32(64 - targetField.bitfieldOffset - targetSize)
+			} else {
+				loadWidth, err := Sizeof(targetField.Type)
+				if err != nil {
+					return zero, err
+				}
+
+				target = uint32(64 - Bits(loadWidth*8) + targetField.bitfieldOffset)
+			}
+			return fixupWithoutValidation(0, target)
+
+		case reloFieldRShiftU64:
+			targetSize, err := targetField.sizeBits()
+			if err != nil {
+				return zero, err
+			}
+
+			return fixupWithoutValidation(0, uint32(64-targetSize))
+		}
+	}
+
+	return zero, fmt.Errorf("relocation %s: %w", relo.kind, ErrNotSupported)
+}
+
+/* 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")
+	}
+
+	parts := strings.Split(accessor, ":")
+	result := make(coreAccessor, 0, len(parts))
+	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
+}
+
+func (ca coreAccessor) String() string {
+	strs := make([]string, 0, len(ca))
+	for _, i := range ca {
+		strs = append(strs, strconv.Itoa(i))
+	}
+	return strings.Join(strs, ":")
+}
+
+func (ca coreAccessor) enumValue(t Type) (*EnumValue, error) {
+	e, ok := t.(*Enum)
+	if !ok {
+		return nil, fmt.Errorf("not an enum: %s", t)
+	}
+
+	if len(ca) > 1 {
+		return nil, fmt.Errorf("invalid accessor %s for enum", ca)
+	}
+
+	i := ca[0]
+	if i >= len(e.Values) {
+		return nil, fmt.Errorf("invalid index %d for %s", i, e)
+	}
+
+	return &e.Values[i], nil
+}
+
+// coreField represents the position of a "child" of a composite type from the
+// start of that type.
+//
+//     /- start of composite
+//     | offset * 8 | bitfieldOffset | bitfieldSize | ... |
+//                  \- start of field       end of field -/
+type coreField struct {
+	Type Type
+
+	// The position of the field from the start of the composite type in bytes.
+	offset uint32
+
+	// The offset of the bitfield in bits from the start of the field.
+	bitfieldOffset Bits
+
+	// The size of the bitfield in bits.
+	//
+	// Zero if the field is not a bitfield.
+	bitfieldSize Bits
+}
+
+func (cf *coreField) adjustOffsetToNthElement(n int) error {
+	size, err := Sizeof(cf.Type)
+	if err != nil {
+		return err
+	}
+
+	cf.offset += uint32(n) * uint32(size)
+	return nil
+}
+
+func (cf *coreField) adjustOffsetBits(offset Bits) error {
+	align, err := alignof(cf.Type)
+	if err != nil {
+		return err
+	}
+
+	// We can compute the load offset by:
+	// 1) converting the bit offset to bytes with a flooring division.
+	// 2) dividing and multiplying that offset by the alignment, yielding the
+	//    load size aligned offset.
+	offsetBytes := uint32(offset/8) / uint32(align) * uint32(align)
+
+	// The number of bits remaining is the bit offset less the number of bits
+	// we can "skip" with the aligned offset.
+	cf.bitfieldOffset = offset - Bits(offsetBytes*8)
+
+	// We know that cf.offset is aligned at to at least align since we get it
+	// from the compiler via BTF. Adding an aligned offsetBytes preserves the
+	// alignment.
+	cf.offset += offsetBytes
+	return nil
+}
+
+func (cf *coreField) sizeBits() (Bits, error) {
+	if cf.bitfieldSize > 0 {
+		return cf.bitfieldSize, nil
+	}
+
+	// Someone is trying to access a non-bitfield via a bit shift relocation.
+	// This happens when a field changes from a bitfield to a regular field
+	// between kernel versions. Synthesise the size to make the shifts work.
+	size, err := Sizeof(cf.Type)
+	if err != nil {
+		return 0, nil
+	}
+	return Bits(size * 8), nil
+}
+
+// coreFindField descends into the local type using the accessor and tries to
+// find an equivalent field in target at each step.
+//
+// Returns the field and the offset of the field from the start of
+// target in bits.
+func coreFindField(localT Type, localAcc coreAccessor, targetT Type) (coreField, coreField, error) {
+	local := coreField{Type: localT}
+	target := coreField{Type: targetT}
+
+	// The first index is used to offset a pointer of the base type like
+	// when accessing an array.
+	if err := local.adjustOffsetToNthElement(localAcc[0]); err != nil {
+		return coreField{}, coreField{}, err
+	}
+
+	if err := target.adjustOffsetToNthElement(localAcc[0]); err != nil {
+		return coreField{}, coreField{}, err
+	}
+
+	if err := coreAreMembersCompatible(local.Type, target.Type); err != nil {
+		return coreField{}, coreField{}, fmt.Errorf("fields: %w", err)
+	}
+
+	var localMaybeFlex, targetMaybeFlex bool
+	for i, acc := range localAcc[1:] {
+		switch localType := local.Type.(type) {
+		case composite:
+			// For composite types acc is used to find the field in the local type,
+			// and then we try to find a field in target with the same name.
+			localMembers := localType.members()
+			if acc >= len(localMembers) {
+				return coreField{}, coreField{}, fmt.Errorf("invalid accessor %d for %s", acc, localType)
+			}
+
+			localMember := localMembers[acc]
+			if localMember.Name == "" {
+				_, ok := localMember.Type.(composite)
+				if !ok {
+					return coreField{}, coreField{}, fmt.Errorf("unnamed field with type %s: %s", localMember.Type, ErrNotSupported)
+				}
+
+				// This is an anonymous struct or union, ignore it.
+				local = coreField{
+					Type:   localMember.Type,
+					offset: local.offset + localMember.Offset.Bytes(),
+				}
+				localMaybeFlex = false
+				continue
+			}
+
+			targetType, ok := target.Type.(composite)
+			if !ok {
+				return coreField{}, coreField{}, fmt.Errorf("target not composite: %w", errImpossibleRelocation)
+			}
+
+			targetMember, last, err := coreFindMember(targetType, localMember.Name)
+			if err != nil {
+				return coreField{}, coreField{}, err
+			}
+
+			local = coreField{
+				Type:         localMember.Type,
+				offset:       local.offset,
+				bitfieldSize: localMember.BitfieldSize,
+			}
+			localMaybeFlex = acc == len(localMembers)-1
+
+			target = coreField{
+				Type:         targetMember.Type,
+				offset:       target.offset,
+				bitfieldSize: targetMember.BitfieldSize,
+			}
+			targetMaybeFlex = last
+
+			if local.bitfieldSize == 0 && target.bitfieldSize == 0 {
+				local.offset += localMember.Offset.Bytes()
+				target.offset += targetMember.Offset.Bytes()
+				break
+			}
+
+			// Either of the members is a bitfield. Make sure we're at the
+			// end of the accessor.
+			if next := i + 1; next < len(localAcc[1:]) {
+				return coreField{}, coreField{}, fmt.Errorf("can't descend into bitfield")
+			}
+
+			if err := local.adjustOffsetBits(localMember.Offset); err != nil {
+				return coreField{}, coreField{}, err
+			}
+
+			if err := target.adjustOffsetBits(targetMember.Offset); err != nil {
+				return coreField{}, coreField{}, err
+			}
+
+		case *Array:
+			// For arrays, acc is the index in the target.
+			targetType, ok := target.Type.(*Array)
+			if !ok {
+				return coreField{}, coreField{}, fmt.Errorf("target not array: %w", errImpossibleRelocation)
+			}
+
+			if localType.Nelems == 0 && !localMaybeFlex {
+				return coreField{}, coreField{}, fmt.Errorf("local type has invalid flexible array")
+			}
+			if targetType.Nelems == 0 && !targetMaybeFlex {
+				return coreField{}, coreField{}, fmt.Errorf("target type has invalid flexible array")
+			}
+
+			if localType.Nelems > 0 && acc >= int(localType.Nelems) {
+				return coreField{}, coreField{}, fmt.Errorf("invalid access of %s at index %d", localType, acc)
+			}
+			if targetType.Nelems > 0 && acc >= int(targetType.Nelems) {
+				return coreField{}, coreField{}, fmt.Errorf("out of bounds access of target: %w", errImpossibleRelocation)
+			}
+
+			local = coreField{
+				Type:   localType.Type,
+				offset: local.offset,
+			}
+			localMaybeFlex = false
+
+			if err := local.adjustOffsetToNthElement(acc); err != nil {
+				return coreField{}, coreField{}, err
+			}
+
+			target = coreField{
+				Type:   targetType.Type,
+				offset: target.offset,
+			}
+			targetMaybeFlex = false
+
+			if err := target.adjustOffsetToNthElement(acc); err != nil {
+				return coreField{}, coreField{}, err
+			}
+
+		default:
+			return coreField{}, coreField{}, fmt.Errorf("relocate field of %T: %w", localType, ErrNotSupported)
+		}
+
+		if err := coreAreMembersCompatible(local.Type, target.Type); err != nil {
+			return coreField{}, coreField{}, err
+		}
+	}
+
+	return local, target, nil
+}
+
+// coreFindMember finds a member in a composite type while handling anonymous
+// structs and unions.
+func coreFindMember(typ composite, name string) (Member, bool, error) {
+	if name == "" {
+		return Member{}, false, errors.New("can't search for anonymous member")
+	}
+
+	type offsetTarget struct {
+		composite
+		offset Bits
+	}
+
+	targets := []offsetTarget{{typ, 0}}
+	visited := make(map[composite]bool)
+
+	for i := 0; i < len(targets); i++ {
+		target := targets[i]
+
+		// Only visit targets once to prevent infinite recursion.
+		if visited[target] {
+			continue
+		}
+		if len(visited) >= maxTypeDepth {
+			// This check is different than libbpf, which restricts the entire
+			// path to BPF_CORE_SPEC_MAX_LEN items.
+			return Member{}, false, fmt.Errorf("type is nested too deep")
+		}
+		visited[target] = true
+
+		members := target.members()
+		for j, member := range members {
+			if member.Name == name {
+				// NB: This is safe because member is a copy.
+				member.Offset += target.offset
+				return member, j == len(members)-1, nil
+			}
+
+			// The names don't match, but this member could be an anonymous struct
+			// or union.
+			if member.Name != "" {
+				continue
+			}
+
+			comp, ok := member.Type.(composite)
+			if !ok {
+				return Member{}, false, fmt.Errorf("anonymous non-composite type %T not allowed", member.Type)
+			}
+
+			targets = append(targets, offsetTarget{comp, target.offset + member.Offset})
+		}
+	}
+
+	return Member{}, false, fmt.Errorf("no matching member: %w", errImpossibleRelocation)
+}
+
+// coreFindEnumValue follows localAcc to find the equivalent enum value in target.
+func coreFindEnumValue(local Type, localAcc coreAccessor, target Type) (localValue, targetValue *EnumValue, _ error) {
+	localValue, err := localAcc.enumValue(local)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	targetEnum, ok := target.(*Enum)
+	if !ok {
+		return nil, nil, errImpossibleRelocation
+	}
+
+	localName := newEssentialName(localValue.Name)
+	for i, targetValue := range targetEnum.Values {
+		if newEssentialName(targetValue.Name) != localName {
+			continue
+		}
+
+		return localValue, &targetEnum.Values[i], nil
+	}
+
+	return nil, nil, errImpossibleRelocation
+}
+
+/* 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.
+ *
+ * Returns errImpossibleRelocation if types are not compatible.
+ */
+func coreAreTypesCompatible(localType Type, targetType Type) 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 errors.New("types are nested too deep")
+		}
+
+		localType = *l
+		targetType = *t
+
+		if reflect.TypeOf(localType) != reflect.TypeOf(targetType) {
+			return fmt.Errorf("type mismatch: %w", errImpossibleRelocation)
+		}
+
+		switch lv := (localType).(type) {
+		case *Void, *Struct, *Union, *Enum, *Fwd, *Int:
+			// Nothing to do here
+
+		case *Pointer, *Array:
+			depth++
+			localType.walk(&localTs)
+			targetType.walk(&targetTs)
+
+		case *FuncProto:
+			tv := targetType.(*FuncProto)
+			if len(lv.Params) != len(tv.Params) {
+				return fmt.Errorf("function param mismatch: %w", errImpossibleRelocation)
+			}
+
+			depth++
+			localType.walk(&localTs)
+			targetType.walk(&targetTs)
+
+		default:
+			return fmt.Errorf("unsupported type %T", localType)
+		}
+	}
+
+	if l != nil {
+		return fmt.Errorf("dangling local type %T", *l)
+	}
+
+	if t != nil {
+		return fmt.Errorf("dangling target type %T", *t)
+	}
+
+	return nil
+}
+
+/* coreAreMembersCompatible checks two types for field-based relocation compatibility.
+ *
+ * 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;
+ *   - any two FLOATs are always compatible;
+ *   - for ARRAY, dimensionality is ignored, element types are checked for
+ *     compatibility recursively;
+ *     [ NB: coreAreMembersCompatible doesn't recurse, this check is done
+ *       by coreFindField. ]
+ *   - 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.
+ *
+ * Returns errImpossibleRelocation if the members are not compatible.
+ */
+func coreAreMembersCompatible(localType Type, targetType Type) error {
+	doNamesMatch := func(a, b string) error {
+		if a == "" || b == "" {
+			// allow anonymous and named type to match
+			return nil
+		}
+
+		if newEssentialName(a) == newEssentialName(b) {
+			return nil
+		}
+
+		return fmt.Errorf("names don't match: %w", errImpossibleRelocation)
+	}
+
+	_, lok := localType.(composite)
+	_, tok := targetType.(composite)
+	if lok && tok {
+		return nil
+	}
+
+	if reflect.TypeOf(localType) != reflect.TypeOf(targetType) {
+		return fmt.Errorf("type mismatch: %w", errImpossibleRelocation)
+	}
+
+	switch lv := localType.(type) {
+	case *Array, *Pointer, *Float, *Int:
+		return nil
+
+	case *Enum:
+		tv := targetType.(*Enum)
+		return doNamesMatch(lv.Name, tv.Name)
+
+	case *Fwd:
+		tv := targetType.(*Fwd)
+		return doNamesMatch(lv.Name, tv.Name)
+
+	default:
+		return fmt.Errorf("type %s: %w", localType, ErrNotSupported)
+	}
+}

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

@@ -0,0 +1,5 @@
+// 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
+package btf

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

@@ -0,0 +1,721 @@
+package btf
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"math"
+	"sort"
+
+	"github.com/cilium/ebpf/asm"
+	"github.com/cilium/ebpf/internal"
+)
+
+// ExtInfos contains ELF section metadata.
+type ExtInfos struct {
+	// The slices are sorted by offset in ascending order.
+	funcInfos       map[string][]funcInfo
+	lineInfos       map[string][]lineInfo
+	relocationInfos map[string][]coreRelocationInfo
+}
+
+// loadExtInfosFromELF parses ext infos from the .BTF.ext section in an ELF.
+//
+// Returns an error wrapping ErrNotFound if no ext infos are present.
+func loadExtInfosFromELF(file *internal.SafeELFFile, ts types, strings *stringTable) (*ExtInfos, error) {
+	section := file.Section(".BTF.ext")
+	if section == nil {
+		return nil, fmt.Errorf("btf ext infos: %w", ErrNotFound)
+	}
+
+	if section.ReaderAt == nil {
+		return nil, fmt.Errorf("compressed ext_info is not supported")
+	}
+
+	return loadExtInfos(section.ReaderAt, file.ByteOrder, ts, strings)
+}
+
+// loadExtInfos parses bare ext infos.
+func loadExtInfos(r io.ReaderAt, bo binary.ByteOrder, ts types, strings *stringTable) (*ExtInfos, error) {
+	// Open unbuffered section reader. binary.Read() calls io.ReadFull on
+	// the header structs, resulting in one syscall per header.
+	headerRd := io.NewSectionReader(r, 0, math.MaxInt64)
+	extHeader, err := parseBTFExtHeader(headerRd, bo)
+	if err != nil {
+		return nil, fmt.Errorf("parsing BTF extension header: %w", err)
+	}
+
+	coreHeader, err := parseBTFExtCOREHeader(headerRd, bo, extHeader)
+	if err != nil {
+		return nil, fmt.Errorf("parsing BTF CO-RE header: %w", err)
+	}
+
+	buf := internal.NewBufferedSectionReader(r, extHeader.funcInfoStart(), int64(extHeader.FuncInfoLen))
+	btfFuncInfos, err := parseFuncInfos(buf, bo, strings)
+	if err != nil {
+		return nil, fmt.Errorf("parsing BTF function info: %w", err)
+	}
+
+	funcInfos := make(map[string][]funcInfo, len(btfFuncInfos))
+	for section, bfis := range btfFuncInfos {
+		funcInfos[section], err = newFuncInfos(bfis, ts)
+		if err != nil {
+			return nil, fmt.Errorf("section %s: func infos: %w", section, err)
+		}
+	}
+
+	buf = internal.NewBufferedSectionReader(r, extHeader.lineInfoStart(), int64(extHeader.LineInfoLen))
+	btfLineInfos, err := parseLineInfos(buf, bo, strings)
+	if err != nil {
+		return nil, fmt.Errorf("parsing BTF line info: %w", err)
+	}
+
+	lineInfos := make(map[string][]lineInfo, len(btfLineInfos))
+	for section, blis := range btfLineInfos {
+		lineInfos[section], err = newLineInfos(blis, strings)
+		if err != nil {
+			return nil, fmt.Errorf("section %s: line infos: %w", section, err)
+		}
+	}
+
+	if coreHeader == nil || coreHeader.COREReloLen == 0 {
+		return &ExtInfos{funcInfos, lineInfos, nil}, nil
+	}
+
+	var btfCORERelos map[string][]bpfCORERelo
+	buf = internal.NewBufferedSectionReader(r, extHeader.coreReloStart(coreHeader), int64(coreHeader.COREReloLen))
+	btfCORERelos, err = parseCORERelos(buf, bo, strings)
+	if err != nil {
+		return nil, fmt.Errorf("parsing CO-RE relocation info: %w", err)
+	}
+
+	coreRelos := make(map[string][]coreRelocationInfo, len(btfCORERelos))
+	for section, brs := range btfCORERelos {
+		coreRelos[section], err = newRelocationInfos(brs, ts, strings)
+		if err != nil {
+			return nil, fmt.Errorf("section %s: CO-RE relocations: %w", section, err)
+		}
+	}
+
+	return &ExtInfos{funcInfos, lineInfos, coreRelos}, nil
+}
+
+type funcInfoMeta struct{}
+type coreRelocationMeta struct{}
+
+// Assign per-section metadata from BTF to a section's instructions.
+func (ei *ExtInfos) Assign(insns asm.Instructions, section string) {
+	funcInfos := ei.funcInfos[section]
+	lineInfos := ei.lineInfos[section]
+	reloInfos := ei.relocationInfos[section]
+
+	iter := insns.Iterate()
+	for iter.Next() {
+		if len(funcInfos) > 0 && funcInfos[0].offset == iter.Offset {
+			iter.Ins.Metadata.Set(funcInfoMeta{}, funcInfos[0].fn)
+			funcInfos = funcInfos[1:]
+		}
+
+		if len(lineInfos) > 0 && lineInfos[0].offset == iter.Offset {
+			*iter.Ins = iter.Ins.WithSource(lineInfos[0].line)
+			lineInfos = lineInfos[1:]
+		}
+
+		if len(reloInfos) > 0 && reloInfos[0].offset == iter.Offset {
+			iter.Ins.Metadata.Set(coreRelocationMeta{}, reloInfos[0].relo)
+			reloInfos = reloInfos[1:]
+		}
+	}
+}
+
+// MarshalExtInfos encodes function and line info embedded in insns into kernel
+// wire format.
+func MarshalExtInfos(insns asm.Instructions, typeID func(Type) (TypeID, error)) (funcInfos, lineInfos []byte, _ error) {
+	iter := insns.Iterate()
+	var fiBuf, liBuf bytes.Buffer
+	for iter.Next() {
+		if fn := FuncMetadata(iter.Ins); fn != nil {
+			fi := &funcInfo{
+				fn:     fn,
+				offset: iter.Offset,
+			}
+			if err := fi.marshal(&fiBuf, typeID); err != nil {
+				return nil, nil, fmt.Errorf("write func info: %w", err)
+			}
+		}
+
+		if line, ok := iter.Ins.Source().(*Line); ok {
+			li := &lineInfo{
+				line:   line,
+				offset: iter.Offset,
+			}
+			if err := li.marshal(&liBuf); err != nil {
+				return nil, nil, fmt.Errorf("write line info: %w", err)
+			}
+		}
+	}
+	return fiBuf.Bytes(), liBuf.Bytes(), nil
+}
+
+// btfExtHeader is found at the start of the .BTF.ext section.
+type btfExtHeader struct {
+	Magic   uint16
+	Version uint8
+	Flags   uint8
+
+	// HdrLen is larger than the size of struct btfExtHeader when it is
+	// immediately followed by a btfExtCOREHeader.
+	HdrLen uint32
+
+	FuncInfoOff uint32
+	FuncInfoLen uint32
+	LineInfoOff uint32
+	LineInfoLen uint32
+}
+
+// parseBTFExtHeader parses the header of the .BTF.ext section.
+func parseBTFExtHeader(r io.Reader, bo binary.ByteOrder) (*btfExtHeader, error) {
+	var header btfExtHeader
+	if err := binary.Read(r, bo, &header); err != nil {
+		return nil, fmt.Errorf("can't read header: %v", err)
+	}
+
+	if header.Magic != btfMagic {
+		return nil, fmt.Errorf("incorrect magic value %v", header.Magic)
+	}
+
+	if header.Version != 1 {
+		return nil, fmt.Errorf("unexpected version %v", header.Version)
+	}
+
+	if header.Flags != 0 {
+		return nil, fmt.Errorf("unsupported flags %v", header.Flags)
+	}
+
+	if int64(header.HdrLen) < int64(binary.Size(&header)) {
+		return nil, fmt.Errorf("header length shorter than btfExtHeader size")
+	}
+
+	return &header, nil
+}
+
+// funcInfoStart returns the offset from the beginning of the .BTF.ext section
+// to the start of its func_info entries.
+func (h *btfExtHeader) funcInfoStart() int64 {
+	return int64(h.HdrLen + h.FuncInfoOff)
+}
+
+// lineInfoStart returns the offset from the beginning of the .BTF.ext section
+// to the start of its line_info entries.
+func (h *btfExtHeader) lineInfoStart() int64 {
+	return int64(h.HdrLen + h.LineInfoOff)
+}
+
+// coreReloStart returns the offset from the beginning of the .BTF.ext section
+// to the start of its CO-RE relocation entries.
+func (h *btfExtHeader) coreReloStart(ch *btfExtCOREHeader) int64 {
+	return int64(h.HdrLen + ch.COREReloOff)
+}
+
+// btfExtCOREHeader is found right after the btfExtHeader when its HdrLen
+// field is larger than its size.
+type btfExtCOREHeader struct {
+	COREReloOff uint32
+	COREReloLen uint32
+}
+
+// parseBTFExtCOREHeader parses the tail of the .BTF.ext header. If additional
+// header bytes are present, extHeader.HdrLen will be larger than the struct,
+// indicating the presence of a CO-RE extension header.
+func parseBTFExtCOREHeader(r io.Reader, bo binary.ByteOrder, extHeader *btfExtHeader) (*btfExtCOREHeader, error) {
+	extHdrSize := int64(binary.Size(&extHeader))
+	remainder := int64(extHeader.HdrLen) - extHdrSize
+
+	if remainder == 0 {
+		return nil, nil
+	}
+
+	var coreHeader btfExtCOREHeader
+	if err := binary.Read(r, bo, &coreHeader); err != nil {
+		return nil, fmt.Errorf("can't read header: %v", err)
+	}
+
+	return &coreHeader, nil
+}
+
+type btfExtInfoSec struct {
+	SecNameOff uint32
+	NumInfo    uint32
+}
+
+// parseExtInfoSec parses a btf_ext_info_sec header within .BTF.ext,
+// appearing within func_info and line_info sub-sections.
+// These headers appear once for each program section in the ELF and are
+// followed by one or more func/line_info records for the section.
+func parseExtInfoSec(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 secName == "" {
+		return "", nil, fmt.Errorf("extinfo header refers to empty section name")
+	}
+
+	if infoHeader.NumInfo == 0 {
+		return "", nil, fmt.Errorf("section %s has zero records", secName)
+	}
+
+	return secName, &infoHeader, nil
+}
+
+// parseExtInfoRecordSize parses the uint32 at the beginning of a func_infos
+// or line_infos segment that describes the length of all extInfoRecords in
+// that segment.
+func parseExtInfoRecordSize(r io.Reader, bo binary.ByteOrder) (uint32, error) {
+	const maxRecordSize = 256
+
+	var recordSize uint32
+	if err := binary.Read(r, bo, &recordSize); err != nil {
+		return 0, fmt.Errorf("can't read record size: %v", err)
+	}
+
+	if recordSize < 4 {
+		// Need at least InsnOff worth of bytes per record.
+		return 0, errors.New("record size too short")
+	}
+	if recordSize > maxRecordSize {
+		return 0, fmt.Errorf("record size %v exceeds %v", recordSize, maxRecordSize)
+	}
+
+	return recordSize, nil
+}
+
+// The size of a FuncInfo in BTF wire format.
+var FuncInfoSize = uint32(binary.Size(bpfFuncInfo{}))
+
+type funcInfo struct {
+	fn     *Func
+	offset asm.RawInstructionOffset
+}
+
+type bpfFuncInfo struct {
+	// Instruction offset of the function within an ELF section.
+	InsnOff uint32
+	TypeID  TypeID
+}
+
+func newFuncInfo(fi bpfFuncInfo, ts types) (*funcInfo, error) {
+	typ, err := ts.ByID(fi.TypeID)
+	if err != nil {
+		return nil, err
+	}
+
+	fn, ok := typ.(*Func)
+	if !ok {
+		return nil, fmt.Errorf("type ID %d is a %T, but expected a Func", fi.TypeID, typ)
+	}
+
+	// C doesn't have anonymous functions, but check just in case.
+	if fn.Name == "" {
+		return nil, fmt.Errorf("func with type ID %d doesn't have a name", fi.TypeID)
+	}
+
+	return &funcInfo{
+		fn,
+		asm.RawInstructionOffset(fi.InsnOff),
+	}, nil
+}
+
+func newFuncInfos(bfis []bpfFuncInfo, ts types) ([]funcInfo, error) {
+	fis := make([]funcInfo, 0, len(bfis))
+	for _, bfi := range bfis {
+		fi, err := newFuncInfo(bfi, ts)
+		if err != nil {
+			return nil, fmt.Errorf("offset %d: %w", bfi.InsnOff, err)
+		}
+		fis = append(fis, *fi)
+	}
+	sort.Slice(fis, func(i, j int) bool {
+		return fis[i].offset <= fis[j].offset
+	})
+	return fis, nil
+}
+
+// marshal into the BTF wire format.
+func (fi *funcInfo) marshal(w io.Writer, typeID func(Type) (TypeID, error)) error {
+	id, err := typeID(fi.fn)
+	if err != nil {
+		return err
+	}
+	bfi := bpfFuncInfo{
+		InsnOff: uint32(fi.offset),
+		TypeID:  id,
+	}
+	return binary.Write(w, internal.NativeEndian, &bfi)
+}
+
+// parseLineInfos parses a func_info sub-section within .BTF.ext ito a map of
+// func infos indexed by section name.
+func parseFuncInfos(r io.Reader, bo binary.ByteOrder, strings *stringTable) (map[string][]bpfFuncInfo, error) {
+	recordSize, err := parseExtInfoRecordSize(r, bo)
+	if err != nil {
+		return nil, err
+	}
+
+	result := make(map[string][]bpfFuncInfo)
+	for {
+		secName, infoHeader, err := parseExtInfoSec(r, bo, strings)
+		if errors.Is(err, io.EOF) {
+			return result, nil
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		records, err := parseFuncInfoRecords(r, bo, recordSize, infoHeader.NumInfo)
+		if err != nil {
+			return nil, fmt.Errorf("section %v: %w", secName, err)
+		}
+
+		result[secName] = records
+	}
+}
+
+// parseFuncInfoRecords parses a stream of func_infos into a funcInfos.
+// These records appear after a btf_ext_info_sec header in the func_info
+// sub-section of .BTF.ext.
+func parseFuncInfoRecords(r io.Reader, bo binary.ByteOrder, recordSize uint32, recordNum uint32) ([]bpfFuncInfo, error) {
+	var out []bpfFuncInfo
+	var fi bpfFuncInfo
+
+	if exp, got := FuncInfoSize, recordSize; exp != got {
+		// BTF blob's record size is longer than we know how to parse.
+		return nil, fmt.Errorf("expected FuncInfo record size %d, but BTF blob contains %d", exp, got)
+	}
+
+	for i := uint32(0); i < recordNum; i++ {
+		if err := binary.Read(r, bo, &fi); err != nil {
+			return nil, fmt.Errorf("can't read function info: %v", err)
+		}
+
+		if fi.InsnOff%asm.InstructionSize != 0 {
+			return nil, fmt.Errorf("offset %v is not aligned with instruction size", fi.InsnOff)
+		}
+
+		// ELF tracks offset in bytes, the kernel expects raw BPF instructions.
+		// Convert as early as possible.
+		fi.InsnOff /= asm.InstructionSize
+
+		out = append(out, fi)
+	}
+
+	return out, nil
+}
+
+var LineInfoSize = uint32(binary.Size(bpfLineInfo{}))
+
+// Line represents the location and contents of a single line of source
+// code a BPF ELF was compiled from.
+type Line struct {
+	fileName   string
+	line       string
+	lineNumber uint32
+	lineColumn uint32
+
+	// TODO: We should get rid of the fields below, but for that we need to be
+	// able to write BTF.
+
+	fileNameOff uint32
+	lineOff     uint32
+}
+
+func (li *Line) FileName() string {
+	return li.fileName
+}
+
+func (li *Line) Line() string {
+	return li.line
+}
+
+func (li *Line) LineNumber() uint32 {
+	return li.lineNumber
+}
+
+func (li *Line) LineColumn() uint32 {
+	return li.lineColumn
+}
+
+func (li *Line) String() string {
+	return li.line
+}
+
+type lineInfo struct {
+	line   *Line
+	offset asm.RawInstructionOffset
+}
+
+// Constants for the format of bpfLineInfo.LineCol.
+const (
+	bpfLineShift = 10
+	bpfLineMax   = (1 << (32 - bpfLineShift)) - 1
+	bpfColumnMax = (1 << bpfLineShift) - 1
+)
+
+type bpfLineInfo struct {
+	// Instruction offset of the line within the whole instruction stream, in instructions.
+	InsnOff     uint32
+	FileNameOff uint32
+	LineOff     uint32
+	LineCol     uint32
+}
+
+func newLineInfo(li bpfLineInfo, strings *stringTable) (*lineInfo, error) {
+	line, err := strings.Lookup(li.LineOff)
+	if err != nil {
+		return nil, fmt.Errorf("lookup of line: %w", err)
+	}
+
+	fileName, err := strings.Lookup(li.FileNameOff)
+	if err != nil {
+		return nil, fmt.Errorf("lookup of filename: %w", err)
+	}
+
+	lineNumber := li.LineCol >> bpfLineShift
+	lineColumn := li.LineCol & bpfColumnMax
+
+	return &lineInfo{
+		&Line{
+			fileName,
+			line,
+			lineNumber,
+			lineColumn,
+			li.FileNameOff,
+			li.LineOff,
+		},
+		asm.RawInstructionOffset(li.InsnOff),
+	}, nil
+}
+
+func newLineInfos(blis []bpfLineInfo, strings *stringTable) ([]lineInfo, error) {
+	lis := make([]lineInfo, 0, len(blis))
+	for _, bli := range blis {
+		li, err := newLineInfo(bli, strings)
+		if err != nil {
+			return nil, fmt.Errorf("offset %d: %w", bli.InsnOff, err)
+		}
+		lis = append(lis, *li)
+	}
+	sort.Slice(lis, func(i, j int) bool {
+		return lis[i].offset <= lis[j].offset
+	})
+	return lis, nil
+}
+
+// marshal writes the binary representation of the LineInfo to w.
+func (li *lineInfo) marshal(w io.Writer) error {
+	line := li.line
+	if line.lineNumber > bpfLineMax {
+		return fmt.Errorf("line %d exceeds %d", line.lineNumber, bpfLineMax)
+	}
+
+	if line.lineColumn > bpfColumnMax {
+		return fmt.Errorf("column %d exceeds %d", line.lineColumn, bpfColumnMax)
+	}
+
+	bli := bpfLineInfo{
+		uint32(li.offset),
+		line.fileNameOff,
+		line.lineOff,
+		(line.lineNumber << bpfLineShift) | line.lineColumn,
+	}
+	return binary.Write(w, internal.NativeEndian, &bli)
+}
+
+// parseLineInfos parses a line_info sub-section within .BTF.ext ito a map of
+// line infos indexed by section name.
+func parseLineInfos(r io.Reader, bo binary.ByteOrder, strings *stringTable) (map[string][]bpfLineInfo, error) {
+	recordSize, err := parseExtInfoRecordSize(r, bo)
+	if err != nil {
+		return nil, err
+	}
+
+	result := make(map[string][]bpfLineInfo)
+	for {
+		secName, infoHeader, err := parseExtInfoSec(r, bo, strings)
+		if errors.Is(err, io.EOF) {
+			return result, nil
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		records, err := parseLineInfoRecords(r, bo, recordSize, infoHeader.NumInfo)
+		if err != nil {
+			return nil, fmt.Errorf("section %v: %w", secName, err)
+		}
+
+		result[secName] = records
+	}
+}
+
+// parseLineInfoRecords parses a stream of line_infos into a lineInfos.
+// These records appear after a btf_ext_info_sec header in the line_info
+// sub-section of .BTF.ext.
+func parseLineInfoRecords(r io.Reader, bo binary.ByteOrder, recordSize uint32, recordNum uint32) ([]bpfLineInfo, error) {
+	var out []bpfLineInfo
+	var li bpfLineInfo
+
+	if exp, got := uint32(binary.Size(li)), recordSize; exp != got {
+		// BTF blob's record size is longer than we know how to parse.
+		return nil, fmt.Errorf("expected LineInfo record size %d, but BTF blob contains %d", exp, got)
+	}
+
+	for i := uint32(0); i < recordNum; i++ {
+		if err := binary.Read(r, bo, &li); err != nil {
+			return nil, fmt.Errorf("can't read line info: %v", err)
+		}
+
+		if li.InsnOff%asm.InstructionSize != 0 {
+			return nil, fmt.Errorf("offset %v is not aligned with instruction size", li.InsnOff)
+		}
+
+		// ELF tracks offset in bytes, the kernel expects raw BPF instructions.
+		// Convert as early as possible.
+		li.InsnOff /= asm.InstructionSize
+
+		out = append(out, li)
+	}
+
+	return out, nil
+}
+
+// bpfCORERelo matches the kernel's struct bpf_core_relo.
+type bpfCORERelo struct {
+	InsnOff      uint32
+	TypeID       TypeID
+	AccessStrOff uint32
+	Kind         coreKind
+}
+
+type CORERelocation struct {
+	typ      Type
+	accessor coreAccessor
+	kind     coreKind
+}
+
+func CORERelocationMetadata(ins *asm.Instruction) *CORERelocation {
+	relo, _ := ins.Metadata.Get(coreRelocationMeta{}).(*CORERelocation)
+	return relo
+}
+
+type coreRelocationInfo struct {
+	relo   *CORERelocation
+	offset asm.RawInstructionOffset
+}
+
+func newRelocationInfo(relo bpfCORERelo, ts types, strings *stringTable) (*coreRelocationInfo, error) {
+	typ, err := ts.ByID(relo.TypeID)
+	if err != nil {
+		return nil, err
+	}
+
+	accessorStr, err := 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)
+	}
+
+	return &coreRelocationInfo{
+		&CORERelocation{
+			typ,
+			accessor,
+			relo.Kind,
+		},
+		asm.RawInstructionOffset(relo.InsnOff),
+	}, nil
+}
+
+func newRelocationInfos(brs []bpfCORERelo, ts types, strings *stringTable) ([]coreRelocationInfo, error) {
+	rs := make([]coreRelocationInfo, 0, len(brs))
+	for _, br := range brs {
+		relo, err := newRelocationInfo(br, ts, strings)
+		if err != nil {
+			return nil, fmt.Errorf("offset %d: %w", br.InsnOff, err)
+		}
+		rs = append(rs, *relo)
+	}
+	sort.Slice(rs, func(i, j int) bool {
+		return rs[i].offset < rs[j].offset
+	})
+	return rs, nil
+}
+
+var extInfoReloSize = binary.Size(bpfCORERelo{})
+
+// parseCORERelos parses a core_relos sub-section within .BTF.ext ito a map of
+// CO-RE relocations indexed by section name.
+func parseCORERelos(r io.Reader, bo binary.ByteOrder, strings *stringTable) (map[string][]bpfCORERelo, error) {
+	recordSize, err := parseExtInfoRecordSize(r, bo)
+	if err != nil {
+		return nil, err
+	}
+
+	if recordSize != uint32(extInfoReloSize) {
+		return nil, fmt.Errorf("expected record size %d, got %d", extInfoReloSize, recordSize)
+	}
+
+	result := make(map[string][]bpfCORERelo)
+	for {
+		secName, infoHeader, err := parseExtInfoSec(r, bo, strings)
+		if errors.Is(err, io.EOF) {
+			return result, nil
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		records, err := parseCOREReloRecords(r, bo, recordSize, infoHeader.NumInfo)
+		if err != nil {
+			return nil, fmt.Errorf("section %v: %w", secName, err)
+		}
+
+		result[secName] = records
+	}
+}
+
+// parseCOREReloRecords parses a stream of CO-RE relocation entries into a
+// coreRelos. These records appear after a btf_ext_info_sec header in the
+// core_relos sub-section of .BTF.ext.
+func parseCOREReloRecords(r io.Reader, bo binary.ByteOrder, recordSize uint32, recordNum uint32) ([]bpfCORERelo, error) {
+	var out []bpfCORERelo
+
+	var relo bpfCORERelo
+	for i := uint32(0); i < recordNum; i++ {
+		if err := binary.Read(r, bo, &relo); err != nil {
+			return nil, fmt.Errorf("can't read CO-RE relocation: %v", err)
+		}
+
+		if relo.InsnOff%asm.InstructionSize != 0 {
+			return nil, fmt.Errorf("offset %v is not aligned with instruction size", relo.InsnOff)
+		}
+
+		// ELF tracks offset in bytes, the kernel expects raw BPF instructions.
+		// Convert as early as possible.
+		relo.InsnOff /= asm.InstructionSize
+
+		out = append(out, relo)
+	}
+
+	return out, nil
+}

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

@@ -0,0 +1,319 @@
+package btf
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+)
+
+var errNestedTooDeep = errors.New("nested too deep")
+
+// GoFormatter converts a Type to Go syntax.
+//
+// A zero GoFormatter is valid to use.
+type GoFormatter struct {
+	w strings.Builder
+
+	// Types present in this map are referred to using the given name if they
+	// are encountered when outputting another type.
+	Names map[Type]string
+
+	// Identifier is called for each field of struct-like types. By default the
+	// field name is used as is.
+	Identifier func(string) string
+
+	// EnumIdentifier is called for each element of an enum. By default the
+	// name of the enum type is concatenated with Identifier(element).
+	EnumIdentifier func(name, element string) string
+}
+
+// TypeDeclaration generates a Go type declaration for a BTF type.
+func (gf *GoFormatter) TypeDeclaration(name string, typ Type) (string, error) {
+	gf.w.Reset()
+	if err := gf.writeTypeDecl(name, typ); err != nil {
+		return "", err
+	}
+	return gf.w.String(), nil
+}
+
+func (gf *GoFormatter) identifier(s string) string {
+	if gf.Identifier != nil {
+		return gf.Identifier(s)
+	}
+
+	return s
+}
+
+func (gf *GoFormatter) enumIdentifier(name, element string) string {
+	if gf.EnumIdentifier != nil {
+		return gf.EnumIdentifier(name, element)
+	}
+
+	return name + gf.identifier(element)
+}
+
+// writeTypeDecl outputs a declaration of the given type.
+//
+// It encodes https://golang.org/ref/spec#Type_declarations:
+//
+//     type foo struct { bar uint32; }
+//     type bar int32
+func (gf *GoFormatter) writeTypeDecl(name string, typ Type) error {
+	if name == "" {
+		return fmt.Errorf("need a name for type %s", typ)
+	}
+
+	switch v := skipQualifiers(typ).(type) {
+	case *Enum:
+		fmt.Fprintf(&gf.w, "type %s ", name)
+		switch v.Size {
+		case 1:
+			gf.w.WriteString("int8")
+		case 2:
+			gf.w.WriteString("int16")
+		case 4:
+			gf.w.WriteString("int32")
+		case 8:
+			gf.w.WriteString("int64")
+		default:
+			return fmt.Errorf("%s: invalid enum size %d", typ, v.Size)
+		}
+
+		if len(v.Values) == 0 {
+			return nil
+		}
+
+		gf.w.WriteString("; const ( ")
+		for _, ev := range v.Values {
+			id := gf.enumIdentifier(name, ev.Name)
+			fmt.Fprintf(&gf.w, "%s %s = %d; ", id, name, ev.Value)
+		}
+		gf.w.WriteString(")")
+
+		return nil
+
+	default:
+		fmt.Fprintf(&gf.w, "type %s ", name)
+		return gf.writeTypeLit(v, 0)
+	}
+}
+
+// writeType outputs the name of a named type or a literal describing the type.
+//
+// It encodes https://golang.org/ref/spec#Types.
+//
+//     foo                  (if foo is a named type)
+//     uint32
+func (gf *GoFormatter) writeType(typ Type, depth int) error {
+	typ = skipQualifiers(typ)
+
+	name := gf.Names[typ]
+	if name != "" {
+		gf.w.WriteString(name)
+		return nil
+	}
+
+	return gf.writeTypeLit(typ, depth)
+}
+
+// writeTypeLit outputs a literal describing the type.
+//
+// The function ignores named types.
+//
+// It encodes https://golang.org/ref/spec#TypeLit.
+//
+//     struct { bar uint32; }
+//     uint32
+func (gf *GoFormatter) writeTypeLit(typ Type, depth int) error {
+	depth++
+	if depth > maxTypeDepth {
+		return errNestedTooDeep
+	}
+
+	var err error
+	switch v := skipQualifiers(typ).(type) {
+	case *Int:
+		gf.writeIntLit(v)
+
+	case *Enum:
+		gf.w.WriteString("int32")
+
+	case *Typedef:
+		err = gf.writeType(v.Type, depth)
+
+	case *Array:
+		fmt.Fprintf(&gf.w, "[%d]", v.Nelems)
+		err = gf.writeType(v.Type, depth)
+
+	case *Struct:
+		err = gf.writeStructLit(v.Size, v.Members, depth)
+
+	case *Union:
+		// Always choose the first member to represent the union in Go.
+		err = gf.writeStructLit(v.Size, v.Members[:1], depth)
+
+	case *Datasec:
+		err = gf.writeDatasecLit(v, depth)
+
+	default:
+		return fmt.Errorf("type %T: %w", v, ErrNotSupported)
+	}
+
+	if err != nil {
+		return fmt.Errorf("%s: %w", typ, err)
+	}
+
+	return nil
+}
+
+func (gf *GoFormatter) writeIntLit(i *Int) {
+	// NB: Encoding.IsChar is ignored.
+	if i.Encoding.IsBool() && i.Size == 1 {
+		gf.w.WriteString("bool")
+		return
+	}
+
+	bits := i.Size * 8
+	if i.Encoding.IsSigned() {
+		fmt.Fprintf(&gf.w, "int%d", bits)
+	} else {
+		fmt.Fprintf(&gf.w, "uint%d", bits)
+	}
+}
+
+func (gf *GoFormatter) writeStructLit(size uint32, members []Member, depth int) error {
+	gf.w.WriteString("struct { ")
+
+	prevOffset := uint32(0)
+	skippedBitfield := false
+	for i, m := range members {
+		if m.BitfieldSize > 0 {
+			skippedBitfield = true
+			continue
+		}
+
+		offset := m.Offset.Bytes()
+		if n := offset - prevOffset; skippedBitfield && n > 0 {
+			fmt.Fprintf(&gf.w, "_ [%d]byte /* unsupported bitfield */; ", n)
+		} else {
+			gf.writePadding(n)
+		}
+
+		size, err := Sizeof(m.Type)
+		if err != nil {
+			return fmt.Errorf("field %d: %w", i, err)
+		}
+		prevOffset = offset + uint32(size)
+
+		if err := gf.writeStructField(m, depth); err != nil {
+			return fmt.Errorf("field %d: %w", i, err)
+		}
+	}
+
+	gf.writePadding(size - prevOffset)
+	gf.w.WriteString("}")
+	return nil
+}
+
+func (gf *GoFormatter) writeStructField(m Member, depth int) error {
+	if m.BitfieldSize > 0 {
+		return fmt.Errorf("bitfields are not supported")
+	}
+	if m.Offset%8 != 0 {
+		return fmt.Errorf("unsupported offset %d", m.Offset)
+	}
+
+	if m.Name == "" {
+		// Special case a nested anonymous union like
+		//     struct foo { union { int bar; int baz }; }
+		// by replacing the whole union with its first member.
+		union, ok := m.Type.(*Union)
+		if !ok {
+			return fmt.Errorf("anonymous fields are not supported")
+
+		}
+
+		if len(union.Members) == 0 {
+			return errors.New("empty anonymous union")
+		}
+
+		depth++
+		if depth > maxTypeDepth {
+			return errNestedTooDeep
+		}
+
+		m := union.Members[0]
+		size, err := Sizeof(m.Type)
+		if err != nil {
+			return err
+		}
+
+		if err := gf.writeStructField(m, depth); err != nil {
+			return err
+		}
+
+		gf.writePadding(union.Size - uint32(size))
+		return nil
+
+	}
+
+	fmt.Fprintf(&gf.w, "%s ", gf.identifier(m.Name))
+
+	if err := gf.writeType(m.Type, depth); err != nil {
+		return err
+	}
+
+	gf.w.WriteString("; ")
+	return nil
+}
+
+func (gf *GoFormatter) writeDatasecLit(ds *Datasec, depth int) error {
+	gf.w.WriteString("struct { ")
+
+	prevOffset := uint32(0)
+	for i, vsi := range ds.Vars {
+		v := vsi.Type.(*Var)
+		if v.Linkage != GlobalVar {
+			// Ignore static, extern, etc. for now.
+			continue
+		}
+
+		if v.Name == "" {
+			return fmt.Errorf("variable %d: empty name", i)
+		}
+
+		gf.writePadding(vsi.Offset - prevOffset)
+		prevOffset = vsi.Offset + vsi.Size
+
+		fmt.Fprintf(&gf.w, "%s ", gf.identifier(v.Name))
+
+		if err := gf.writeType(v.Type, depth); err != nil {
+			return fmt.Errorf("variable %d: %w", i, err)
+		}
+
+		gf.w.WriteString("; ")
+	}
+
+	gf.writePadding(ds.Size - prevOffset)
+	gf.w.WriteString("}")
+	return nil
+}
+
+func (gf *GoFormatter) writePadding(bytes uint32) {
+	if bytes > 0 {
+		fmt.Fprintf(&gf.w, "_ [%d]byte; ", bytes)
+	}
+}
+
+func skipQualifiers(typ Type) Type {
+	result := typ
+	for depth := 0; depth <= maxTypeDepth; depth++ {
+		switch v := (result).(type) {
+		case qualifier:
+			result = v.qualify()
+		default:
+			return result
+		}
+	}
+	return &cycle{typ}
+}

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

@@ -0,0 +1,121 @@
+package btf
+
+import (
+	"errors"
+	"fmt"
+	"os"
+
+	"github.com/cilium/ebpf/internal/sys"
+	"github.com/cilium/ebpf/internal/unix"
+)
+
+// HandleInfo describes a Handle.
+type HandleInfo struct {
+	// ID of this handle in the kernel. The ID is only valid as long as the
+	// associated handle is kept alive.
+	ID ID
+
+	// Name is an identifying name for the BTF, currently only used by the
+	// kernel.
+	Name string
+
+	// IsKernel is true if the BTF originated with the kernel and not
+	// userspace.
+	IsKernel bool
+
+	// Size of the raw BTF in bytes.
+	size uint32
+}
+
+func newHandleInfoFromFD(fd *sys.FD) (*HandleInfo, error) {
+	// We invoke the syscall once with a empty BTF and name buffers to get size
+	// information to allocate buffers. Then we invoke it a second time with
+	// buffers to receive the data.
+	var btfInfo sys.BtfInfo
+	if err := sys.ObjInfo(fd, &btfInfo); err != nil {
+		return nil, fmt.Errorf("get BTF info for fd %s: %w", fd, err)
+	}
+
+	if btfInfo.NameLen > 0 {
+		// NameLen doesn't account for the terminating NUL.
+		btfInfo.NameLen++
+	}
+
+	// Don't pull raw BTF by default, since it may be quite large.
+	btfSize := btfInfo.BtfSize
+	btfInfo.BtfSize = 0
+
+	nameBuffer := make([]byte, btfInfo.NameLen)
+	btfInfo.Name, btfInfo.NameLen = sys.NewSlicePointerLen(nameBuffer)
+	if err := sys.ObjInfo(fd, &btfInfo); err != nil {
+		return nil, err
+	}
+
+	return &HandleInfo{
+		ID:       ID(btfInfo.Id),
+		Name:     unix.ByteSliceToString(nameBuffer),
+		IsKernel: btfInfo.KernelBtf != 0,
+		size:     btfSize,
+	}, nil
+}
+
+// IsModule returns true if the BTF is for the kernel itself.
+func (i *HandleInfo) IsVmlinux() bool {
+	return i.IsKernel && i.Name == "vmlinux"
+}
+
+// IsModule returns true if the BTF is for a kernel module.
+func (i *HandleInfo) IsModule() bool {
+	return i.IsKernel && i.Name != "vmlinux"
+}
+
+// HandleIterator allows enumerating BTF blobs loaded into the kernel.
+type HandleIterator struct {
+	// The ID of the last retrieved handle. Only valid after a call to Next.
+	ID  ID
+	err error
+}
+
+// Next retrieves a handle for the next BTF blob.
+//
+// [Handle.Close] is called if *handle is non-nil to avoid leaking fds.
+//
+// Returns true if another BTF blob was found. Call [HandleIterator.Err] after
+// the function returns false.
+func (it *HandleIterator) Next(handle **Handle) bool {
+	if *handle != nil {
+		(*handle).Close()
+		*handle = nil
+	}
+
+	id := it.ID
+	for {
+		attr := &sys.BtfGetNextIdAttr{Id: id}
+		err := sys.BtfGetNextId(attr)
+		if errors.Is(err, os.ErrNotExist) {
+			// There are no more BTF objects.
+			return false
+		} else if err != nil {
+			it.err = fmt.Errorf("get next BTF ID: %w", err)
+			return false
+		}
+
+		id = attr.NextId
+		*handle, err = NewHandleFromID(id)
+		if errors.Is(err, os.ErrNotExist) {
+			// Try again with the next ID.
+			continue
+		} else if err != nil {
+			it.err = fmt.Errorf("retrieve handle for ID %d: %w", id, err)
+			return false
+		}
+
+		it.ID = id
+		return true
+	}
+}
+
+// Err returns an error if iteration failed for some reason.
+func (it *HandleIterator) Err() error {
+	return it.err
+}

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

@@ -0,0 +1,128 @@
+package btf
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+)
+
+type stringTable struct {
+	base    *stringTable
+	offsets []uint32
+	strings []string
+}
+
+// sizedReader is implemented by bytes.Reader, io.SectionReader, strings.Reader, etc.
+type sizedReader interface {
+	io.Reader
+	Size() int64
+}
+
+func readStringTable(r sizedReader, base *stringTable) (*stringTable, error) {
+	// When parsing split BTF's string table, the first entry offset is derived
+	// from the last entry offset of the base BTF.
+	firstStringOffset := uint32(0)
+	if base != nil {
+		idx := len(base.offsets) - 1
+		firstStringOffset = base.offsets[idx] + uint32(len(base.strings[idx])) + 1
+	}
+
+	// Derived from vmlinux BTF.
+	const averageStringLength = 16
+
+	n := int(r.Size() / averageStringLength)
+	offsets := make([]uint32, 0, n)
+	strings := make([]string, 0, n)
+
+	offset := firstStringOffset
+	scanner := bufio.NewScanner(r)
+	scanner.Split(splitNull)
+	for scanner.Scan() {
+		str := scanner.Text()
+		offsets = append(offsets, offset)
+		strings = append(strings, str)
+		offset += uint32(len(str)) + 1
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	if len(strings) == 0 {
+		return nil, errors.New("string table is empty")
+	}
+
+	if firstStringOffset == 0 && strings[0] != "" {
+		return nil, errors.New("first item in string table is non-empty")
+	}
+
+	return &stringTable{base, offsets, strings}, nil
+}
+
+func splitNull(data []byte, atEOF bool) (advance int, token []byte, err error) {
+	i := bytes.IndexByte(data, 0)
+	if i == -1 {
+		if atEOF && len(data) > 0 {
+			return 0, nil, errors.New("string table isn't null terminated")
+		}
+		return 0, nil, nil
+	}
+
+	return i + 1, data[:i], nil
+}
+
+func (st *stringTable) Lookup(offset uint32) (string, error) {
+	if st.base != nil && offset <= st.base.offsets[len(st.base.offsets)-1] {
+		return st.base.lookup(offset)
+	}
+	return st.lookup(offset)
+}
+
+func (st *stringTable) lookup(offset uint32) (string, error) {
+	i := search(st.offsets, offset)
+	if i == len(st.offsets) || st.offsets[i] != offset {
+		return "", fmt.Errorf("offset %d isn't start of a string", offset)
+	}
+
+	return st.strings[i], nil
+}
+
+func (st *stringTable) Length() int {
+	last := len(st.offsets) - 1
+	return int(st.offsets[last]) + len(st.strings[last]) + 1
+}
+
+func (st *stringTable) Marshal(w io.Writer) error {
+	for _, str := range st.strings {
+		_, err := io.WriteString(w, str)
+		if err != nil {
+			return err
+		}
+		_, err = w.Write([]byte{0})
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// search is a copy of sort.Search specialised for uint32.
+//
+// Licensed under https://go.dev/LICENSE
+func search(ints []uint32, needle uint32) int {
+	// Define f(-1) == false and f(n) == true.
+	// Invariant: f(i-1) == false, f(j) == true.
+	i, j := 0, len(ints)
+	for i < j {
+		h := int(uint(i+j) >> 1) // avoid overflow when computing h
+		// i ≤ h < j
+		if !(ints[h] >= needle) {
+			i = h + 1 // preserves f(i-1) == false
+		} else {
+			j = h // preserves f(j) == true
+		}
+	}
+	// i == j, f(i-1) == false, and f(j) (= f(i)) == true  =>  answer is i.
+	return i
+}