Use instruction metadata to simplify linking and CO-RE relocation

cmd/bpf2go/output.go

@@ -343,16 +343,12 @@ func collectCTypes(types *btf.Spec, names []string) ([]btf.Type, error) {
 func collectMapTypes(maps map[string]*ebpf.MapSpec) []btf.Type {
 	var result []btf.Type
 	for _, m := range maps {
-		if m.BTF == nil {
-			continue
-		}
-
-		if m.BTF.Key != nil && m.BTF.Key.TypeName() != "" {
-			result = append(result, m.BTF.Key)
+		if m.Key != nil && m.Key.TypeName() != "" {
+			result = append(result, m.Key)
 		}
 
-		if m.BTF.Value != nil && m.BTF.Value.TypeName() != "" {
-			result = append(result, m.BTF.Value)
+		if m.Value != nil && m.Value.TypeName() != "" {
+			result = append(result, m.Value)
 		}
 	}
 	return result

collection.go

@@ -145,7 +145,7 @@ func (cs *CollectionSpec) RewriteConstants(consts map[string]interface{}) error
 	buf := make([]byte, len(value))
 	copy(buf, value)
 
-	err := patchValue(buf, rodata.BTF.Value, consts)
+	err := patchValue(buf, rodata.Value, consts)
 	if err != nil {
 		return err
 	}
@@ -454,7 +454,7 @@ func (cl *collectionLoader) loadMap(mapName string) (*Map, error) {
 		return nil, fmt.Errorf("missing map %s", mapName)
 	}
 
-	if mapSpec.BTF != nil && cl.coll.Types != mapSpec.BTF.Spec {
+	if mapSpec.BTF != nil && cl.coll.Types != mapSpec.BTF {
 		return nil, fmt.Errorf("map %s: BTF doesn't match collection", mapName)
 	}
 
@@ -494,7 +494,7 @@ func (cl *collectionLoader) loadProgram(progName string) (*Program, error) {
 		return nil, fmt.Errorf("cannot load program %s: program type is unspecified", progName)
 	}
 
-	if progSpec.BTF != nil && cl.coll.Types != progSpec.BTF.Spec() {
+	if progSpec.BTF != nil && cl.coll.Types != progSpec.BTF {
 		return nil, fmt.Errorf("program %s: BTF doesn't match collection", progName)
 	}
 

elf_reader.go

@@ -26,6 +26,7 @@ type elfCode struct {
 	license  string
 	version  uint32
 	btf      *btf.Spec
+	extInfo  *btf.ExtInfos
 }
 
 // LoadCollectionSpec parses an ELF file into a CollectionSpec.
@@ -94,7 +95,7 @@ func LoadCollectionSpecFromReader(rd io.ReaderAt) (*CollectionSpec, error) {
 		return nil, fmt.Errorf("load version: %w", err)
 	}
 
-	btfSpec, err := btf.LoadSpecFromReader(rd)
+	btfSpec, btfExtInfo, err := btf.LoadSpecAndExtInfosFromReader(rd)
 	if err != nil && !errors.Is(err, btf.ErrNotFound) {
 		return nil, fmt.Errorf("load BTF: %w", err)
 	}
@@ -105,6 +106,7 @@ func LoadCollectionSpecFromReader(rd io.ReaderAt) (*CollectionSpec, error) {
 		license:     license,
 		version:     version,
 		btf:         btfSpec,
+		extInfo:     btfExtInfo,
 	}
 
 	symbols, err := f.Symbols()
@@ -309,13 +311,7 @@ func (ec *elfCode) loadProgramSections() (map[string]*ProgramSpec, error) {
 				KernelVersion: ec.version,
 				Instructions:  insns,
 				ByteOrder:     ec.ByteOrder,
-			}
-
-			if ec.btf != nil {
-				spec.BTF, err = ec.btf.Program(name)
-				if err != nil && !errors.Is(err, btf.ErrNoExtendedInfo) {
-					return nil, fmt.Errorf("program %s: %w", name, err)
-				}
+				BTF:           ec.btf,
 			}
 
 			// Function names must be unique within a single ELF blob.
@@ -383,6 +379,10 @@ func (ec *elfCode) loadFunctions(section *elfSection) (map[string]asm.Instructio
 		}
 	}
 
+	if ec.extInfo != nil {
+		ec.extInfo.Assign(insns, section.Name)
+	}
+
 	return splitSymbols(insns)
 }
 
@@ -904,7 +904,9 @@ func mapSpecFromBTF(es *elfSection, vs *btf.VarSecinfo, def *btf.Struct, spec *b
 		ValueSize:  valueSize,
 		MaxEntries: maxEntries,
 		Flags:      flags,
-		BTF:        &btf.Map{Spec: spec, Key: key, Value: value},
+		Key:        key,
+		Value:      value,
+		BTF:        spec,
 		Pinning:    pinType,
 		InnerMap:   innerMapSpec,
 		Contents:   contents,
@@ -1039,7 +1041,9 @@ func (ec *elfCode) loadDataSections(maps map[string]*MapSpec) error {
 			ValueSize:  uint32(len(data)),
 			MaxEntries: 1,
 			Contents:   []MapKV{{uint32(0), data}},
-			BTF:        &btf.Map{Spec: ec.btf, Key: &btf.Void{}, Value: datasec},
+			Key:        &btf.Void{},
+			Value:      datasec,
+			BTF:        ec.btf,
 		}
 
 		switch sec.Name {

elf_reader_test.go

@@ -142,9 +142,10 @@ func TestLoadCollectionSpec(t *testing.T) {
 			}
 			return false
 		}),
-		cmpopts.IgnoreTypes(new(btf.Map), new(btf.Program)),
+		cmpopts.IgnoreTypes(new(btf.Spec)),
 		cmpopts.IgnoreFields(CollectionSpec{}, "ByteOrder", "Types"),
 		cmpopts.IgnoreFields(ProgramSpec{}, "Instructions", "ByteOrder"),
+		cmpopts.IgnoreFields(MapSpec{}, "Key", "Value"),
 		cmpopts.IgnoreUnexported(ProgramSpec{}),
 		cmpopts.IgnoreMapEntries(func(key string, _ *MapSpec) bool {
 			switch key {