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btf: use recursion in coreAreTypesCompatible #1383

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merged 1 commit into from
Mar 22, 2024
Merged

btf: use recursion in coreAreTypesCompatible #1383

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89 changes: 47 additions & 42 deletions btf/core.go
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Original file line number Diff line number Diff line change
Expand Up @@ -374,7 +374,7 @@ func coreCalculateFixup(relo *CORERelocation, target Type, targetID TypeID, bo b
return zero, fmt.Errorf("unexpected accessor %v", relo.accessor)
}

err := coreAreTypesCompatible(local, target)
err := CheckTypeCompatibility(local, target)
if errors.Is(err, errIncompatibleTypes) {
return poison()
}
Expand Down Expand Up @@ -901,7 +901,11 @@ func coreFindEnumValue(local Type, localAcc coreAccessor, target Type) (localVal
//
// Only layout compatibility is checked, ignoring names of the root type.
func CheckTypeCompatibility(localType Type, targetType Type) error {
return coreAreTypesCompatible(localType, targetType)
return coreAreTypesCompatible(localType, targetType, nil)
}

type pair struct {
A, B Type
}

/* The comment below is from bpf_core_types_are_compat in libbpf.c:
Expand All @@ -927,59 +931,60 @@ func CheckTypeCompatibility(localType Type, targetType Type) error {
*
* Returns errIncompatibleTypes if types are not compatible.
*/
func coreAreTypesCompatible(localType Type, targetType Type) error {
func coreAreTypesCompatible(localType Type, targetType Type, visited map[pair]struct{}) error {
localType = UnderlyingType(localType)
targetType = UnderlyingType(targetType)

var (
localTs, targetTs typeDeque
l, t = &localType, &targetType
depth = 0
)
if reflect.TypeOf(localType) != reflect.TypeOf(targetType) {
return fmt.Errorf("type mismatch between %v and %v: %w", localType, targetType, errIncompatibleTypes)
}

for ; l != nil && t != nil; l, t = localTs.Shift(), targetTs.Shift() {
if depth >= maxResolveDepth {
return errors.New("types are nested too deep")
}
if _, ok := visited[pair{localType, targetType}]; ok {
return nil
}
if visited == nil {
visited = make(map[pair]struct{})
}
visited[pair{localType, targetType}] = struct{}{}

localType = UnderlyingType(*l)
targetType = UnderlyingType(*t)
switch lv := localType.(type) {
case *Void, *Struct, *Union, *Enum, *Fwd, *Int:
return nil

if reflect.TypeOf(localType) != reflect.TypeOf(targetType) {
return fmt.Errorf("type mismatch between %v and %v: %w", localType, targetType, errIncompatibleTypes)
}
case *Pointer:
tv := targetType.(*Pointer)
return coreAreTypesCompatible(lv.Target, tv.Target, visited)

switch lv := (localType).(type) {
case *Void, *Struct, *Union, *Enum, *Fwd, *Int:
// Nothing to do here
case *Array:
tv := targetType.(*Array)
if err := coreAreTypesCompatible(lv.Index, tv.Index, visited); err != nil {
return err
}

case *Pointer, *Array:
depth++
walkType(localType, localTs.Push)
walkType(targetType, targetTs.Push)
return coreAreTypesCompatible(lv.Type, tv.Type, visited)

case *FuncProto:
tv := targetType.(*FuncProto)
if len(lv.Params) != len(tv.Params) {
return fmt.Errorf("function param mismatch: %w", errIncompatibleTypes)
}
case *FuncProto:
tv := targetType.(*FuncProto)
if err := coreAreTypesCompatible(lv.Return, tv.Return, visited); err != nil {
return err
}

depth++
walkType(localType, localTs.Push)
walkType(targetType, targetTs.Push)
if len(lv.Params) != len(tv.Params) {
return fmt.Errorf("function param mismatch: %w", errIncompatibleTypes)
}

default:
return fmt.Errorf("unsupported type %T", localType)
for i, localParam := range lv.Params {
targetParam := tv.Params[i]
if err := coreAreTypesCompatible(localParam.Type, targetParam.Type, visited); err != nil {
return err
}
}
}

if l != nil {
return fmt.Errorf("dangling local type %T", *l)
}
return nil

if t != nil {
return fmt.Errorf("dangling target type %T", *t)
default:
return fmt.Errorf("unsupported type %T", localType)
}

return nil
}

/* coreAreMembersCompatible checks two types for field-based relocation compatibility.
Expand Down
44 changes: 5 additions & 39 deletions btf/core_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -17,42 +17,6 @@ import (
)

func TestCheckTypeCompatibility(t *testing.T) {
tests := []struct {
a, b Type
compatible bool
}{
{&FuncProto{Return: &Typedef{Type: &Int{}}}, &FuncProto{Return: &Int{}}, true},
{&FuncProto{Return: &Typedef{Type: &Int{}}}, &FuncProto{Return: &Void{}}, false},
}
for _, test := range tests {
err := CheckTypeCompatibility(test.a, test.b)
if test.compatible {
if err != nil {
t.Errorf("Expected types to be compatible: %s\na = %#v\nb = %#v", err, test.a, test.b)
continue
}
} else {
if !errors.Is(err, errIncompatibleTypes) {
t.Errorf("Expected types to be incompatible: %s\na = %#v\nb = %#v", err, test.a, test.b)
continue
}
}

err = CheckTypeCompatibility(test.b, test.a)
if test.compatible {
if err != nil {
t.Errorf("Expected reversed types to be compatible: %s\na = %#v\nb = %#v", err, test.a, test.b)
}
} else {
if !errors.Is(err, errIncompatibleTypes) {
t.Errorf("Expected reversed types to be incompatible: %s\na = %#v\nb = %#v", err, test.a, test.b)
}
}
}

}

func TestCOREAreTypesCompatible(t *testing.T) {
tests := []struct {
a, b Type
compatible bool
Expand Down Expand Up @@ -84,10 +48,12 @@ func TestCOREAreTypesCompatible(t *testing.T) {
&FuncProto{Return: &Void{}, Params: []FuncParam{{Type: &Void{}}}},
false,
},
{&FuncProto{Return: &Typedef{Type: &Int{}}}, &FuncProto{Return: &Int{}}, true},
{&FuncProto{Return: &Typedef{Type: &Int{}}}, &FuncProto{Return: &Void{}}, false},
}

for _, test := range tests {
err := coreAreTypesCompatible(test.a, test.b)
err := CheckTypeCompatibility(test.a, test.b)
if test.compatible {
if err != nil {
t.Errorf("Expected types to be compatible: %s\na = %#v\nb = %#v", err, test.a, test.b)
Expand All @@ -100,7 +66,7 @@ func TestCOREAreTypesCompatible(t *testing.T) {
}
}

err = coreAreTypesCompatible(test.b, test.a)
err = CheckTypeCompatibility(test.b, test.a)
if test.compatible {
if err != nil {
t.Errorf("Expected reversed types to be compatible: %s\na = %#v\nb = %#v", err, test.a, test.b)
Expand All @@ -113,7 +79,7 @@ func TestCOREAreTypesCompatible(t *testing.T) {
}

for _, invalid := range []Type{&Var{}, &Datasec{}} {
err := coreAreTypesCompatible(invalid, invalid)
err := CheckTypeCompatibility(invalid, invalid)
if errors.Is(err, errIncompatibleTypes) {
t.Errorf("Expected an error for %T, not errIncompatibleTypes", invalid)
} else if err == nil {
Expand Down
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