Frame pointers are not used if erts_frame_layout is undefined

Author: GregMefford

interpreter/beam/beam.go

@@ -42,6 +42,7 @@ type beamData struct {
 	the_active_code_index  uint64
 	r                      uint64
 	erts_atom_table        uint64
+	frame_pointer_support  bool
 	erts_frame_layout      uint64
 	etp_ptr_mask           uint64
 	etp_header_subtag_mask uint64
@@ -214,22 +215,25 @@ func Loader(ebpf interpreter.EbpfHandler, info *interpreter.LoaderInfo) (interpr
 		return nil, fmt.Errorf("symbol 'etp_heap_bits_subtag' not found: %v", err)
 	}
 
-	erts_frame_layout, _, err := ef.SymbolData("erts_frame_layout", 8)
-	if err != nil {
-		return nil, fmt.Errorf("symbol 'erts_frame_layout' not found: %v", err)
-	}
-
 	d := &beamData{
 		version:                otpVersion,
 		the_active_code_index:  uint64(codeIndex.Address),
 		r:                      uint64(r),
 		erts_atom_table:        uint64(atomTable.Address),
-		erts_frame_layout:      uint64(erts_frame_layout.Address),
+		frame_pointer_support:  true,
 		etp_ptr_mask:           nopanicslicereader.Uint64(etp_ptr_mask, 0),
 		etp_header_subtag_mask: nopanicslicereader.Uint64(etp_header_subtag_mask, 0),
 		etp_heap_bits_subtag:   nopanicslicereader.Uint64(etp_heap_bits_subtag, 0),
 	}
 
+	erts_frame_layout, _, err := ef.SymbolData("erts_frame_layout", 8)
+	if err != nil {
+		// If erts_frame_layout is not defined, that's OK - it just means that
+		// frame pointers are not supported and therefore not used.
+		d.frame_pointer_support = false
+	}
+	d.erts_frame_layout = uint64(erts_frame_layout.Address)
+
 	vms := &d.vmStructs
 
 	// These values are the same on OTP releases 27.2.4 and 28.0.2.
@@ -277,11 +281,17 @@ func Loader(ebpf interpreter.EbpfHandler, info *interpreter.LoaderInfo) (interpr
 func (d *beamData) Attach(ebpf interpreter.EbpfHandler, pid libpf.PID, bias libpf.Address, rm remotememory.RemoteMemory) (interpreter.Instance, error) {
 	log.Infof("BEAM attaching, bias: 0x%x", bias)
 
+	// If frame pointers are not supported, they will not be used
+	Erts_frame_layout := uint64(0)
+	if d.frame_pointer_support {
+		Erts_frame_layout = rm.Uint64(bias + libpf.Address(d.erts_frame_layout))
+	}
+
 	data := support.BEAMProcInfo{
 		Version:               d.version,
 		R:                     uint64(bias) + d.r,
 		The_active_code_index: uint64(bias) + d.the_active_code_index,
-		Erts_frame_layout:     rm.Uint64(bias + libpf.Address(d.erts_frame_layout)),
+		Erts_frame_layout:     Erts_frame_layout,
 		Ranges_sizeof:         uint8(d.vmStructs.ranges.size_of),
 		Ranges_modules:        uint8(d.vmStructs.ranges.modules),
 		Ranges_n:              uint8(d.vmStructs.ranges.n),