info: expose ksym info and func info by ProgramInfo

btf/ext_info.go

@@ -16,7 +16,7 @@ import (
 // ExtInfos contains ELF section metadata.
 type ExtInfos struct {
 	// The slices are sorted by offset in ascending order.
-	funcInfos       map[string]FuncInfos
+	funcInfos       map[string]FuncOffsets
 	lineInfos       map[string]LineInfos
 	relocationInfos map[string]CORERelocationInfos
 }
@@ -58,9 +58,9 @@ func loadExtInfos(r io.ReaderAt, bo binary.ByteOrder, spec *Spec) (*ExtInfos, er
 		return nil, fmt.Errorf("parsing BTF function info: %w", err)
 	}
 
-	funcInfos := make(map[string]FuncInfos, len(btfFuncInfos))
+	funcInfos := make(map[string]FuncOffsets, len(btfFuncInfos))
 	for section, bfis := range btfFuncInfos {
-		funcInfos[section], err = newFuncInfos(bfis, spec)
+		funcInfos[section], err = newFuncOffsets(bfis, spec)
 		if err != nil {
 			return nil, fmt.Errorf("section %s: func infos: %w", section, err)
 		}
@@ -117,15 +117,15 @@ func (ei *ExtInfos) Assign(insns asm.Instructions, section string) {
 // Assign per-instruction metadata to the instructions in insns.
 func AssignMetadataToInstructions(
 	insns asm.Instructions,
-	funcInfos FuncInfos,
+	funcInfos FuncOffsets,
 	lineInfos LineInfos,
 	reloInfos CORERelocationInfos,
 ) {
 	iter := insns.Iterate()
 	for iter.Next() {
-		if len(funcInfos.infos) > 0 && funcInfos.infos[0].offset == iter.Offset {
-			*iter.Ins = WithFuncMetadata(*iter.Ins, funcInfos.infos[0].fn)
-			funcInfos.infos = funcInfos.infos[1:]
+		if len(funcInfos) > 0 && funcInfos[0].Offset == iter.Offset {
+			*iter.Ins = WithFuncMetadata(*iter.Ins, funcInfos[0].Func)
+			funcInfos = funcInfos[1:]
 		}
 
 		if len(lineInfos.infos) > 0 && lineInfos.infos[0].offset == iter.Offset {
@@ -159,9 +159,9 @@ marshal:
 	var fiBuf, liBuf bytes.Buffer
 	for {
 		if fn := FuncMetadata(iter.Ins); fn != nil {
-			fi := &funcInfo{
-				fn:     fn,
-				offset: iter.Offset,
+			fi := &FuncOffset{
+				Func:   fn,
+				Offset: iter.Offset,
 			}
 			if err := fi.marshal(&fiBuf, b); err != nil {
 				return nil, nil, fmt.Errorf("write func info: %w", err)
@@ -333,17 +333,17 @@ func parseExtInfoRecordSize(r io.Reader, bo binary.ByteOrder) (uint32, error) {
 	return recordSize, nil
 }
 
-// FuncInfos contains a sorted list of func infos.
-type FuncInfos struct {
-	infos []funcInfo
-}
+// FuncOffsets is a sorted slice of FuncOffset.
+type FuncOffsets []FuncOffset
 
 // The size of a FuncInfo in BTF wire format.
 var FuncInfoSize = uint32(binary.Size(bpfFuncInfo{}))
 
-type funcInfo struct {
-	fn     *Func
-	offset asm.RawInstructionOffset
+// FuncOffset represents a [btf.Func] and its raw instruction offset within a
+// BPF program.
+type FuncOffset struct {
+	Offset asm.RawInstructionOffset
+	Func   *Func
 }
 
 type bpfFuncInfo struct {
@@ -352,7 +352,7 @@ type bpfFuncInfo struct {
 	TypeID  TypeID
 }
 
-func newFuncInfo(fi bpfFuncInfo, spec *Spec) (*funcInfo, error) {
+func newFuncOffset(fi bpfFuncInfo, spec *Spec) (*FuncOffset, error) {
 	typ, err := spec.TypeByID(fi.TypeID)
 	if err != nil {
 		return nil, err
@@ -368,31 +368,32 @@ func newFuncInfo(fi bpfFuncInfo, spec *Spec) (*funcInfo, error) {
 		return nil, fmt.Errorf("func with type ID %d doesn't have a name", fi.TypeID)
 	}
 
-	return &funcInfo{
-		fn,
+	return &FuncOffset{
 		asm.RawInstructionOffset(fi.InsnOff),
+		fn,
 	}, nil
 }
 
-func newFuncInfos(bfis []bpfFuncInfo, spec *Spec) (FuncInfos, error) {
-	fis := FuncInfos{
-		infos: make([]funcInfo, 0, len(bfis)),
-	}
+func newFuncOffsets(bfis []bpfFuncInfo, spec *Spec) (FuncOffsets, error) {
+	fos := make(FuncOffsets, 0, len(bfis))
+
 	for _, bfi := range bfis {
-		fi, err := newFuncInfo(bfi, spec)
+		fi, err := newFuncOffset(bfi, spec)
 		if err != nil {
-			return FuncInfos{}, fmt.Errorf("offset %d: %w", bfi.InsnOff, err)
+			return FuncOffsets{}, fmt.Errorf("offset %d: %w", bfi.InsnOff, err)
 		}
-		fis.infos = append(fis.infos, *fi)
+		fos = append(fos, *fi)
 	}
-	sort.Slice(fis.infos, func(i, j int) bool {
-		return fis.infos[i].offset <= fis.infos[j].offset
+	sort.Slice(fos, func(i, j int) bool {
+		return fos[i].Offset <= fos[j].Offset
 	})
-	return fis, nil
+	return fos, nil
 }
 
-// LoadFuncInfos parses BTF func info in kernel wire format.
-func LoadFuncInfos(reader io.Reader, bo binary.ByteOrder, recordNum uint32, spec *Spec) (FuncInfos, error) {
+// LoadFuncInfos parses BTF func info from kernel wire format into a
+// [FuncOffsets], a sorted slice of [btf.Func]s of (sub)programs within a BPF
+// program with their corresponding raw instruction offsets.
+func LoadFuncInfos(reader io.Reader, bo binary.ByteOrder, recordNum uint32, spec *Spec) (FuncOffsets, error) {
 	fis, err := parseFuncInfoRecords(
 		reader,
 		bo,
@@ -401,20 +402,20 @@ func LoadFuncInfos(reader io.Reader, bo binary.ByteOrder, recordNum uint32, spec
 		false,
 	)
 	if err != nil {
-		return FuncInfos{}, fmt.Errorf("parsing BTF func info: %w", err)
+		return FuncOffsets{}, fmt.Errorf("parsing BTF func info: %w", err)
 	}
 
-	return newFuncInfos(fis, spec)
+	return newFuncOffsets(fis, spec)
 }
 
 // marshal into the BTF wire format.
-func (fi *funcInfo) marshal(w *bytes.Buffer, b *Builder) error {
-	id, err := b.Add(fi.fn)
+func (fi *FuncOffset) marshal(w *bytes.Buffer, b *Builder) error {
+	id, err := b.Add(fi.Func)
 	if err != nil {
 		return err
 	}
 	bfi := bpfFuncInfo{
-		InsnOff: uint32(fi.offset),
+		InsnOff: uint32(fi.Offset),
 		TypeID:  id,
 	}
 	buf := make([]byte, FuncInfoSize)

info.go

@@ -12,7 +12,6 @@ import (
 	"strings"
 	"syscall"
 	"time"
-	"unsafe"
 
 	"github.com/cilium/ebpf/asm"
 	"github.com/cilium/ebpf/btf"
@@ -204,6 +203,8 @@ type ProgramInfo struct {
 	numLineInfos uint32
 	funcInfos    []byte
 	numFuncInfos uint32
+	ksymInfos    []uint64
+	numKsymInfos uint32
 }
 
 func newProgramInfoFromFd(fd *sys.FD) (*ProgramInfo, error) {
@@ -240,7 +241,7 @@ func newProgramInfoFromFd(fd *sys.FD) (*ProgramInfo, error) {
 	if info.NrMapIds > 0 {
 		pi.maps = make([]MapID, info.NrMapIds)
 		info2.NrMapIds = info.NrMapIds
-		info2.MapIds = sys.NewPointer(unsafe.Pointer(&pi.maps[0]))
+		info2.MapIds = sys.NewSlicePointer(pi.maps)
 		makeSecondCall = true
 	} else if haveProgramInfoMapIDs() == nil {
 		// This program really has no associated maps.
@@ -281,6 +282,14 @@ func newProgramInfoFromFd(fd *sys.FD) (*ProgramInfo, error) {
 		makeSecondCall = true
 	}
 
+	if info.NrJitedKsyms > 0 {
+		pi.ksymInfos = make([]uint64, info.NrJitedKsyms)
+		info2.JitedKsyms = sys.NewSlicePointer(pi.ksymInfos)
+		info2.NrJitedKsyms = info.NrJitedKsyms
+		pi.numKsymInfos = info.NrJitedKsyms
+		makeSecondCall = true
+	}
+
 	if makeSecondCall {
 		if err := sys.ObjInfo(fd, &info2); err != nil {
 			return nil, err
@@ -508,6 +517,53 @@ func (pi *ProgramInfo) VerifiedInstructions() (uint32, bool) {
 	return pi.verifiedInstructions, pi.verifiedInstructions > 0
 }
 
+// KsymAddrs returns the ksym addresses of the BPF program, including its
+// subprograms. The addresses correspond to their symbols in /proc/kallsyms.
+//
+// Available from 4.18.
+//
+// The bool return value indicates whether this optional field is available.
+func (pi *ProgramInfo) KsymAddrs() ([]uintptr, bool) {
+	addrs := make([]uintptr, 0, len(pi.ksymInfos))
+	for _, addr := range pi.ksymInfos {
+		addrs = append(addrs, uintptr(addr))
+	}
+	return addrs, pi.numKsymInfos > 0
+}
+
+// FuncInfos returns the offset and function information of all (sub)programs in
+// a BPF program.
+//
+// Available from 5.0.
+//
+// Requires CAP_SYS_ADMIN or equivalent for reading BTF information. Returns
+// ErrNotSupported if the program was created without BTF or if the kernel
+// doesn't support the field.
+func (pi *ProgramInfo) FuncInfos() (btf.FuncOffsets, error) {
+	id, ok := pi.BTFID()
+	if pi.numFuncInfos == 0 || !ok {
+		return nil, fmt.Errorf("program created without BTF or unsupported kernel: %w", ErrNotSupported)
+	}
+
+	h, err := btf.NewHandleFromID(id)
+	if err != nil {
+		return nil, fmt.Errorf("get BTF handle: %w", err)
+	}
+	defer h.Close()
+
+	spec, err := h.Spec(nil)
+	if err != nil {
+		return nil, fmt.Errorf("get BTF spec: %w", err)
+	}
+
+	return btf.LoadFuncInfos(
+		bytes.NewReader(pi.funcInfos),
+		internal.NativeEndian,
+		pi.numFuncInfos,
+		spec,
+	)
+}
+
 func scanFdInfo(fd *sys.FD, fields map[string]interface{}) error {
 	fh, err := os.Open(fmt.Sprintf("/proc/self/fdinfo/%d", fd.Int()))
 	if err != nil {

info_test.go

@@ -510,3 +510,55 @@ func TestZero(t *testing.T) {
 	qt.Assert(t, qt.IsTrue(zero(&inul)))
 	qt.Assert(t, qt.IsFalse(zero(&ione)))
 }
+
+func TestProgInfoKsym(t *testing.T) {
+	testutils.SkipOnOldKernel(t, "4.18", "Program ksym addresses")
+
+	spec, err := LoadCollectionSpec(testutils.NativeFile(t, "testdata/loader-%s.elf"))
+	qt.Assert(t, qt.IsNil(err))
+
+	var obj struct {
+		Prog *Program `ebpf:"xdp_prog"`
+	}
+	err = spec.LoadAndAssign(&obj, nil)
+	testutils.SkipIfNotSupported(t, err)
+	qt.Assert(t, qt.IsNil(err))
+	defer obj.Prog.Close()
+
+	info, err := obj.Prog.Info()
+	qt.Assert(t, qt.IsNil(err))
+
+	addrs, ok := info.KsymAddrs()
+	qt.Assert(t, qt.IsTrue(ok))
+	qt.Assert(t, qt.HasLen(addrs, 5))
+	for _, addr := range addrs {
+		qt.Assert(t, qt.Not(qt.Equals(addr, 0)))
+	}
+}
+
+func TestProgInfoFuncInfos(t *testing.T) {
+	testutils.SkipOnOldKernel(t, "5.0", "Program func info")
+
+	spec, err := LoadCollectionSpec(testutils.NativeFile(t, "testdata/loader-%s.elf"))
+	qt.Assert(t, qt.IsNil(err))
+
+	var obj struct {
+		Prog *Program `ebpf:"xdp_prog"`
+	}
+	err = spec.LoadAndAssign(&obj, nil)
+	testutils.SkipIfNotSupported(t, err)
+	qt.Assert(t, qt.IsNil(err))
+	defer obj.Prog.Close()
+
+	info, err := obj.Prog.Info()
+	qt.Assert(t, qt.IsNil(err))
+
+	funcs, err := info.FuncInfos()
+	qt.Assert(t, qt.IsNil(err))
+
+	qt.Assert(t, qt.HasLen(funcs, 5))
+	for _, fo := range funcs {
+		qt.Assert(t, qt.IsNotNil(fo.Func))
+		qt.Assert(t, qt.Not(qt.Equals(fo.Func.Name, "")))
+	}
+}

internal/cmd/gentypes/main.go

@@ -200,6 +200,7 @@ import (
 				replace(pointer, "xlated_prog_insns"),
 				replace(pointer, "map_ids"),
 				replace(pointer, "line_info"),
+				replace(pointer, "jited_ksyms"),
 				replace(pointer, "func_info"),
 				replace(btfID, "btf_id", "attach_btf_obj_id"),
 				replace(typeID, "attach_btf_id"),

internal/sys/ptr.go

@@ -11,13 +11,13 @@ func NewPointer(ptr unsafe.Pointer) Pointer {
 	return Pointer{ptr: ptr}
 }
 
-// NewSlicePointer creates a 64-bit pointer from a byte slice.
-func NewSlicePointer(buf []byte) Pointer {
+// NewSlicePointer creates a 64-bit pointer from a slice.
+func NewSlicePointer[T comparable](buf []T) Pointer {
 	if len(buf) == 0 {
 		return Pointer{}
 	}
 
-	return Pointer{ptr: unsafe.Pointer(&buf[0])}
+	return Pointer{ptr: unsafe.Pointer(unsafe.SliceData(buf))}
 }
 
 // NewSlicePointerLen creates a 64-bit pointer from a byte slice.

internal/sys/types.go

@@ -733,7 +733,7 @@ type ProgInfo struct {
 	NetnsIno             uint64
 	NrJitedKsyms         uint32
 	NrJitedFuncLens      uint32
-	JitedKsyms           uint64
+	JitedKsyms           Pointer
 	JitedFuncLens        uint64
 	BtfId                BTFID
 	FuncInfoRecSize      uint32