1 files changed, 281 insertions, 0 deletions
diff --git a/vendor/github.com/cilium/ebpf/internal/btf/ext_info.go b/vendor/github.com/cilium/ebpf/internal/btf/ext_info.go
new file mode 100644
index 000000000..6a21b6bda
--- /dev/null
+++ b/vendor/github.com/cilium/ebpf/internal/btf/ext_info.go
@@ -0,0 +1,281 @@
+package btf
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+
+	"github.com/cilium/ebpf/asm"
+	"github.com/cilium/ebpf/internal"
+)
+
+type btfExtHeader struct {
+	Magic   uint16
+	Version uint8
+	Flags   uint8
+	HdrLen  uint32
+
+	FuncInfoOff uint32
+	FuncInfoLen uint32
+	LineInfoOff uint32
+	LineInfoLen uint32
+}
+
+type btfExtCoreHeader struct {
+	CoreReloOff uint32
+	CoreReloLen uint32
+}
+
+func parseExtInfos(r io.ReadSeeker, bo binary.ByteOrder, strings stringTable) (funcInfo, lineInfo map[string]extInfo, coreRelos map[string]bpfCoreRelos, err error) {
+	var header btfExtHeader
+	var coreHeader btfExtCoreHeader
+	if err := binary.Read(r, bo, &header); err != nil {
+		return nil, nil, nil, fmt.Errorf("can't read header: %v", err)
+	}
+
+	if header.Magic != btfMagic {
+		return nil, nil, nil, fmt.Errorf("incorrect magic value %v", header.Magic)
+	}
+
+	if header.Version != 1 {
+		return nil, nil, nil, fmt.Errorf("unexpected version %v", header.Version)
+	}
+
+	if header.Flags != 0 {
+		return nil, nil, nil, fmt.Errorf("unsupported flags %v", header.Flags)
+	}
+
+	remainder := int64(header.HdrLen) - int64(binary.Size(&header))
+	if remainder < 0 {
+		return nil, nil, nil, errors.New("header is too short")
+	}
+
+	coreHdrSize := int64(binary.Size(&coreHeader))
+	if remainder >= coreHdrSize {
+		if err := binary.Read(r, bo, &coreHeader); err != nil {
+			return nil, nil, nil, fmt.Errorf("can't read CO-RE relocation header: %v", err)
+		}
+		remainder -= coreHdrSize
+	}
+
+	// Of course, the .BTF.ext header has different semantics than the
+	// .BTF ext header. We need to ignore non-null values.
+	_, err = io.CopyN(ioutil.Discard, r, remainder)
+	if err != nil {
+		return nil, nil, nil, fmt.Errorf("header padding: %v", err)
+	}
+
+	if _, err := r.Seek(int64(header.HdrLen+header.FuncInfoOff), io.SeekStart); err != nil {
+		return nil, nil, nil, fmt.Errorf("can't seek to function info section: %v", err)
+	}
+
+	buf := bufio.NewReader(io.LimitReader(r, int64(header.FuncInfoLen)))
+	funcInfo, err = parseExtInfo(buf, bo, strings)
+	if err != nil {
+		return nil, nil, nil, fmt.Errorf("function info: %w", err)
+	}
+
+	if _, err := r.Seek(int64(header.HdrLen+header.LineInfoOff), io.SeekStart); err != nil {
+		return nil, nil, nil, fmt.Errorf("can't seek to line info section: %v", err)
+	}
+
+	buf = bufio.NewReader(io.LimitReader(r, int64(header.LineInfoLen)))
+	lineInfo, err = parseExtInfo(buf, bo, strings)
+	if err != nil {
+		return nil, nil, nil, fmt.Errorf("line info: %w", err)
+	}
+
+	if coreHeader.CoreReloOff > 0 && coreHeader.CoreReloLen > 0 {
+		if _, err := r.Seek(int64(header.HdrLen+coreHeader.CoreReloOff), io.SeekStart); err != nil {
+			return nil, nil, nil, fmt.Errorf("can't seek to CO-RE relocation section: %v", err)
+		}
+
+		coreRelos, err = parseExtInfoRelos(io.LimitReader(r, int64(coreHeader.CoreReloLen)), bo, strings)
+		if err != nil {
+			return nil, nil, nil, fmt.Errorf("CO-RE relocation info: %w", err)
+		}
+	}
+
+	return funcInfo, lineInfo, coreRelos, nil
+}
+
+type btfExtInfoSec struct {
+	SecNameOff uint32
+	NumInfo    uint32
+}
+
+type extInfoRecord struct {
+	InsnOff uint64
+	Opaque  []byte
+}
+
+type extInfo struct {
+	recordSize uint32
+	records    []extInfoRecord
+}
+
+func (ei extInfo) append(other extInfo, offset uint64) (extInfo, error) {
+	if other.recordSize != ei.recordSize {
+		return extInfo{}, fmt.Errorf("ext_info record size mismatch, want %d (got %d)", ei.recordSize, other.recordSize)
+	}
+
+	records := make([]extInfoRecord, 0, len(ei.records)+len(other.records))
+	records = append(records, ei.records...)
+	for _, info := range other.records {
+		records = append(records, extInfoRecord{
+			InsnOff: info.InsnOff + offset,
+			Opaque:  info.Opaque,
+		})
+	}
+	return extInfo{ei.recordSize, records}, nil
+}
+
+func (ei extInfo) MarshalBinary() ([]byte, error) {
+	if len(ei.records) == 0 {
+		return nil, nil
+	}
+
+	buf := bytes.NewBuffer(make([]byte, 0, int(ei.recordSize)*len(ei.records)))
+	for _, info := range ei.records {
+		// The kernel expects offsets in number of raw bpf instructions,
+		// while the ELF tracks it in bytes.
+		insnOff := uint32(info.InsnOff / asm.InstructionSize)
+		if err := binary.Write(buf, internal.NativeEndian, insnOff); err != nil {
+			return nil, fmt.Errorf("can't write instruction offset: %v", err)
+		}
+
+		buf.Write(info.Opaque)
+	}
+
+	return buf.Bytes(), nil
+}
+
+func parseExtInfo(r io.Reader, bo binary.ByteOrder, strings stringTable) (map[string]extInfo, error) {
+	const maxRecordSize = 256
+
+	var recordSize uint32
+	if err := binary.Read(r, bo, &recordSize); err != nil {
+		return nil, fmt.Errorf("can't read record size: %v", err)
+	}
+
+	if recordSize < 4 {
+		// Need at least insnOff
+		return nil, errors.New("record size too short")
+	}
+	if recordSize > maxRecordSize {
+		return nil, fmt.Errorf("record size %v exceeds %v", recordSize, maxRecordSize)
+	}
+
+	result := make(map[string]extInfo)
+	for {
+		secName, infoHeader, err := parseExtInfoHeader(r, bo, strings)
+		if errors.Is(err, io.EOF) {
+			return result, nil
+		}
+
+		var records []extInfoRecord
+		for i := uint32(0); i < infoHeader.NumInfo; i++ {
+			var byteOff uint32
+			if err := binary.Read(r, bo, &byteOff); err != nil {
+				return nil, fmt.Errorf("section %v: can't read extended info offset: %v", secName, err)
+			}
+
+			buf := make([]byte, int(recordSize-4))
+			if _, err := io.ReadFull(r, buf); err != nil {
+				return nil, fmt.Errorf("section %v: can't read record: %v", secName, err)
+			}
+
+			if byteOff%asm.InstructionSize != 0 {
+				return nil, fmt.Errorf("section %v: offset %v is not aligned with instruction size", secName, byteOff)
+			}
+
+			records = append(records, extInfoRecord{uint64(byteOff), buf})
+		}
+
+		result[secName] = extInfo{
+			recordSize,
+			records,
+		}
+	}
+}
+
+// bpfCoreRelo matches `struct bpf_core_relo` from the kernel
+type bpfCoreRelo struct {
+	InsnOff      uint32
+	TypeID       TypeID
+	AccessStrOff uint32
+	ReloKind     coreReloKind
+}
+
+type bpfCoreRelos []bpfCoreRelo
+
+// append two slices of extInfoRelo to each other. The InsnOff of b are adjusted
+// by offset.
+func (r bpfCoreRelos) append(other bpfCoreRelos, offset uint64) bpfCoreRelos {
+	result := make([]bpfCoreRelo, 0, len(r)+len(other))
+	result = append(result, r...)
+	for _, relo := range other {
+		relo.InsnOff += uint32(offset)
+		result = append(result, relo)
+	}
+	return result
+}
+
+var extInfoReloSize = binary.Size(bpfCoreRelo{})
+
+func parseExtInfoRelos(r io.Reader, bo binary.ByteOrder, strings stringTable) (map[string]bpfCoreRelos, error) {
+	var recordSize uint32
+	if err := binary.Read(r, bo, &recordSize); err != nil {
+		return nil, fmt.Errorf("read record size: %v", err)
+	}
+
+	if recordSize != uint32(extInfoReloSize) {
+		return nil, fmt.Errorf("expected record size %d, got %d", extInfoReloSize, recordSize)
+	}
+
+	result := make(map[string]bpfCoreRelos)
+	for {
+		secName, infoHeader, err := parseExtInfoHeader(r, bo, strings)
+		if errors.Is(err, io.EOF) {
+			return result, nil
+		}
+
+		var relos []bpfCoreRelo
+		for i := uint32(0); i < infoHeader.NumInfo; i++ {
+			var relo bpfCoreRelo
+			if err := binary.Read(r, bo, &relo); err != nil {
+				return nil, fmt.Errorf("section %v: read record: %v", secName, err)
+			}
+
+			if relo.InsnOff%asm.InstructionSize != 0 {
+				return nil, fmt.Errorf("section %v: offset %v is not aligned with instruction size", secName, relo.InsnOff)
+			}
+
+			relos = append(relos, relo)
+		}
+
+		result[secName] = relos
+	}
+}
+
+func parseExtInfoHeader(r io.Reader, bo binary.ByteOrder, strings stringTable) (string, *btfExtInfoSec, error) {
+	var infoHeader btfExtInfoSec
+	if err := binary.Read(r, bo, &infoHeader); err != nil {
+		return "", nil, fmt.Errorf("read ext info header: %w", err)
+	}
+
+	secName, err := strings.Lookup(infoHeader.SecNameOff)
+	if err != nil {
+		return "", nil, fmt.Errorf("get section name: %w", err)
+	}
+
+	if infoHeader.NumInfo == 0 {
+		return "", nil, fmt.Errorf("section %s has zero records", secName)
+	}
+
+	return secName, &infoHeader, nil
+}