Method associateStructOpsRelocs

elf_reader.go:1520–1560

associateStructOpsRelocs handles `.struct_ops.link` and associates the target function with the correct struct member in the map.

(progs map[string]*ProgramSpec)

// associateStructOpsRelocs handles `.struct_ops.link`
// and associates the target function with the correct struct member in the map.
func (ec *elfCode) associateStructOpsRelocs(progs map[string]*ProgramSpec) error {
	for _, sec := range ec.sections {
		if sec.kind != structOpsSection {
			continue
		}

		userData, err := sec.Data()
		if err != nil {
			return fmt.Errorf("failed to read section data: %w", err)
		}

		if ec.btf == nil {
			return fmt.Errorf("struct_ops section %s: missing BTF", sec.Name)
		}

		// Resolve the BTF datasec describing variables in this section.
		var ds *btf.Datasec
		if err := ec.btf.TypeByName(sec.Name, &ds); err != nil {
			return fmt.Errorf("datasec %s: %w", sec.Name, err)
		}

		// Set flags for .struct_ops.link (BPF_F_LINK).
		flags := uint32(0)
		if sec.Name == structOpsLinkSec {
			flags = sys.BPF_F_LINK
		}

		for _, vsi := range ds.Vars {
			userSt, baseOff, err := ec.createStructOpsMap(vsi, userData, flags)
			if err != nil {
				return err
			}

			if err := structOpsSetAttachTo(sec, baseOff, userSt, progs); err != nil {
				return err
			}
		}
	}

	return nil
}

// createStructOpsMap() creates and registers a MapSpec for a struct_ops
func (ec *elfCode) createStructOpsMap(vsi btf.VarSecinfo, userData []byte, flags uint32) (*btf.Struct, uint32, error) {