Remove inlined function PC resolution for stack traces, remove DWARF …

…caching (DataDog#32166)

Signed-off-by: grantseltzer <[email protected]>

pkg/dynamicinstrumentation/di.go

@@ -80,9 +80,7 @@ func RunDynamicInstrumentation(opts *DIOptions) (*GoDI, error) {
 	if err != nil {
 		return nil, err
 	}
-	stopFunctions := []func(){
-		diagnostics.StopGlobalDiagnostics,
-	}
+	stopFunctions := []func(){}
 	if opts.ReaderWriterOptions.CustomReaderWriters {
 		cm, err := diconfig.NewReaderConfigManager()
 		if err != nil {

pkg/dynamicinstrumentation/diconfig/config_manager.go

@@ -127,7 +127,7 @@ func (cm *RCConfigManager) installConfigProbe(procInfo *ditypes.ProcessInfo) err
 	svcConfigProbe := *configProbe
 	svcConfigProbe.ServiceName = procInfo.ServiceName
 	procInfo.ProbesByID[configProbe.ID] = &svcConfigProbe
-
+	log.Infof("Installing config probe for service: %s.", svcConfigProbe.ServiceName)
 	err = AnalyzeBinary(procInfo)
 	if err != nil {
 		return fmt.Errorf("could not analyze binary for config probe: %w", err)

pkg/dynamicinstrumentation/diconfig/dwarf.go

@@ -26,8 +26,6 @@ func getTypeMap(dwarfData *dwarf.Data, targetFunctions map[string]bool) (*ditype
 	return loadFunctionDefinitions(dwarfData, targetFunctions)
 }
 
-var dwarfMap = make(map[string]*dwarf.Data)
-
 type seenTypeCounter struct {
 	parameter *ditypes.Parameter
 	count     uint8
@@ -42,12 +40,12 @@ func loadFunctionDefinitions(dwarfData *dwarf.Data, targetFunctions map[string]b
 	var funcName string
 
 	var result = ditypes.TypeMap{
-		Functions:        make(map[string][]ditypes.Parameter),
-		InlinedFunctions: make(map[uint64][]*dwarf.Entry),
+		Functions: make(map[string][]ditypes.Parameter),
 	}
 
 	var (
 		name       string
+		isReturn   bool
 		typeFields *ditypes.Parameter
 	)
 
@@ -83,25 +81,6 @@ entryLoop:
 			}
 		}
 
-		if entry.Tag == dwarf.TagInlinedSubroutine {
-			// This is a inlined function
-			for i := range entry.Field {
-				// Find it's high program counter (where it exits in the parent routine)
-				if entry.Field[i].Attr == dwarf.AttrHighpc {
-
-					// The field for HighPC can be a constant or address, which are int64 and uint64 respectively
-					if entry.Field[i].Class == dwarf.ClassConstant {
-						result.InlinedFunctions[uint64(entry.Field[i].Val.(int64))] =
-							append([]*dwarf.Entry{entry}, result.InlinedFunctions[uint64(entry.Field[i].Val.(int64))]...)
-					} else if entry.Field[i].Class == dwarf.ClassAddress {
-						result.InlinedFunctions[entry.Field[i].Val.(uint64)] =
-							append([]*dwarf.Entry{entry}, result.InlinedFunctions[entry.Field[i].Val.(uint64)]...)
-					}
-				}
-			}
-			continue entryLoop
-		}
-
 		if entry.Tag == dwarf.TagSubprogram {
 
 			for _, field := range entry.Field {
@@ -144,6 +123,10 @@ entryLoop:
 				name = entry.Field[i].Val.(string)
 			}
 
+			if entry.Field[i].Attr == dwarf.AttrVarParam {
+				isReturn = entry.Field[i].Val.(bool)
+			}
+
 			// Collect information about the type of this ditypes.Parameter
 			if entry.Field[i].Attr == dwarf.AttrType {
 
@@ -161,7 +144,7 @@ entryLoop:
 			}
 		}
 
-		if typeFields != nil {
+		if typeFields != nil && !isReturn /* we ignore return values for now */ {
 			// We've collected information about this ditypes.Parameter, append it to the slice of ditypes.Parameters for this function
 			typeFields.Name = name
 			result.Functions[funcName] = append(result.Functions[funcName], *typeFields)
@@ -181,19 +164,15 @@ entryLoop:
 }
 
 func loadDWARF(binaryPath string) (*dwarf.Data, error) {
-	if dwarfData, ok := dwarfMap[binaryPath]; ok {
-		return dwarfData, nil
-	}
 	elfFile, err := safeelf.Open(binaryPath)
 	if err != nil {
 		return nil, fmt.Errorf("couldn't open elf binary: %w", err)
 	}
-
+	defer elfFile.Close()
 	dwarfData, err := elfFile.DWARF()
 	if err != nil {
 		return nil, fmt.Errorf("couldn't retrieve debug info from elf: %w", err)
 	}
-	dwarfMap[binaryPath] = dwarfData
 	return dwarfData, nil
 }
 

pkg/dynamicinstrumentation/ditypes/analysis.go

@@ -12,16 +12,11 @@ import (
 	"fmt"
 )
 
-// TypeMap contains all the information about functions and their parameters including
-// functions that have been inlined in the binary
+// TypeMap contains all the information about functions and their parameters
 type TypeMap struct {
 	// Functions maps fully-qualified function names to a slice of its parameters
 	Functions map[string][]Parameter
 
-	// InlinedFunctions maps program counters to a slice of dwarf entries used
-	// when resolving stack traces that include inlined functions
-	InlinedFunctions map[uint64][]*dwarf.Entry
-
 	// FunctionsByPC places DWARF subprogram (function) entries in order by
 	// its low program counter which is necessary for resolving stack traces
 	FunctionsByPC []*LowPCEntry

pkg/dynamicinstrumentation/module/module.go

@@ -32,7 +32,8 @@ func NewModule(config *Config) (*Module, error) { //nolint:revive // TODO
 			ProbesFilePath:   coreconfig.SystemProbe().GetString("dynamic_instrumentation.probes_file_path"),
 			SnapshotOutput:   coreconfig.SystemProbe().GetString("dynamic_instrumentation.snapshot_output_file_path"),
 			DiagnosticOutput: coreconfig.SystemProbe().GetString("dynamic_instrumentation.diagnostics_output_file_path"),
-		}})
+		},
+	})
 	if err != nil {
 		return nil, err
 	}

pkg/dynamicinstrumentation/uploader/stack_trace.go

@@ -30,23 +30,6 @@ func parseStackTrace(procInfo *ditypes.ProcessInfo, rawProgramCounters []uint64)
 			break
 		}
 
-		entries, ok := procInfo.TypeMap.InlinedFunctions[rawProgramCounters[i]]
-		if ok {
-			for n := range entries {
-				inlinedFuncInfo, err := pcToLine(procInfo, rawProgramCounters[i])
-				if err != nil {
-					return stackTrace, fmt.Errorf("could not resolve pc to inlined function info: %w", err)
-				}
-
-				symName, lineNumber, err := parseInlinedEntry(procInfo.DwarfData.Reader(), entries[n])
-				if err != nil {
-					return stackTrace, fmt.Errorf("could not get inlined entries: %w", err)
-				}
-				stackFrame := ditypes.StackFrame{Function: fmt.Sprintf("%s [inlined in %s]", symName, inlinedFuncInfo.fn), FileName: inlinedFuncInfo.file, Line: int(lineNumber)}
-				stackTrace = append(stackTrace, stackFrame)
-			}
-		}
-
 		funcInfo, err := pcToLine(procInfo, rawProgramCounters[i])
 		if err != nil {
 			return stackTrace, fmt.Errorf("could not resolve pc to function info: %w", err)
@@ -122,30 +105,3 @@ func pcToLine(procInfo *ditypes.ProcessInfo, pc uint64) (*funcInfo, error) {
 		fn:   fn,
 	}, nil
 }
-
-func parseInlinedEntry(reader *dwarf.Reader, e *dwarf.Entry) (name string, line int64, err error) {
-
-	var offset dwarf.Offset
-
-	for i := range e.Field {
-		if e.Field[i].Attr == dwarf.AttrAbstractOrigin {
-			offset = e.Field[i].Val.(dwarf.Offset)
-			reader.Seek(offset)
-			entry, err := reader.Next()
-			if err != nil {
-				return "", -1, fmt.Errorf("could not read inlined function origin: %w", err)
-			}
-			for j := range entry.Field {
-				if entry.Field[j].Attr == dwarf.AttrName {
-					name = entry.Field[j].Val.(string)
-				}
-			}
-		}
-
-		if e.Field[i].Attr == dwarf.AttrCallLine {
-			line = e.Field[i].Val.(int64)
-		}
-	}
-
-	return name, line, nil
-}