link/kprobe: Sanitize kprobe symbol for tracefs

Since we allow `.` in symbol names, we need to sanitize
those symbols to please tracefs.

Signed-off-by: Hengqi Chen <chenhengqi@outlook.com>

link/kprobe.go

@@ -321,7 +321,7 @@ func tracefsProbe(typ probeType, args probeArgs) (*perfEvent, error) {
 	// check if an event with the same group and name already exists.
 	// Kernels 4.x and earlier don't return os.ErrExist on writing a duplicate
 	// entry, so we need to rely on reads for detecting uniqueness.
-	_, err = getTraceEventID(group, args.symbol)
+	_, err = getTraceEventID(group, sanitizedSymbol(args.symbol))
 	if err == nil {
 		return nil, fmt.Errorf("trace event already exists: %s/%s", group, args.symbol)
 	}
@@ -335,7 +335,7 @@ func tracefsProbe(typ probeType, args probeArgs) (*perfEvent, error) {
 	}
 
 	// Get the newly-created trace event's id.
-	tid, err := getTraceEventID(group, args.symbol)
+	tid, err := getTraceEventID(group, sanitizedSymbol(args.symbol))
 	if err != nil {
 		return nil, fmt.Errorf("getting trace event id: %w", err)
 	}
@@ -385,7 +385,7 @@ func createTraceFSProbeEvent(typ probeType, args probeArgs) error {
 		// subsampling or rate limiting logic can be more accurately implemented in
 		// the eBPF program itself.
 		// See Documentation/kprobes.txt for more details.
-		pe = fmt.Sprintf("%s:%s/%s %s", probePrefix(args.ret), args.group, args.symbol, args.symbol)
+		pe = fmt.Sprintf("%s:%s/%s %s", probePrefix(args.ret), args.group, sanitizedSymbol(args.symbol), args.symbol)
 	case uprobeType:
 		// The uprobe_events syntax is as follows:
 		// p[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS] : Set a probe

link/uprobe.go

@@ -16,9 +16,9 @@ import (
 var (
 	uprobeEventsPath = filepath.Join(tracefsPath, "uprobe_events")
 
-	// rgxUprobeSymbol is used to strip invalid characters from the uprobe symbol
+	// rgxEventSymbol is used to strip invalid characters from the [k,u]probe symbol
 	// as they are not allowed to be used as the EVENT token in tracefs.
-	rgxUprobeSymbol = regexp.MustCompile("[^a-zA-Z0-9]+")
+	rgxEventSymbol = regexp.MustCompile("[^a-zA-Z0-9]+")
 
 	uprobeRetprobeBit = struct {
 		once  sync.Once
@@ -296,7 +296,7 @@ func (ex *Executable) uprobe(symbol string, prog *ebpf.Program, opts *UprobeOpti
 	}
 
 	// Use tracefs if uprobe PMU is missing.
-	args.symbol = uprobeSanitizedSymbol(symbol)
+	args.symbol = sanitizedSymbol(symbol)
 	tp, err = tracefsUprobe(args)
 	if err != nil {
 		return nil, fmt.Errorf("creating trace event '%s:%s' in tracefs: %w", ex.path, symbol, err)
@@ -315,9 +315,9 @@ func tracefsUprobe(args probeArgs) (*perfEvent, error) {
 	return tracefsProbe(uprobeType, args)
 }
 
-// uprobeSanitizedSymbol replaces every invalid characted for the tracefs api with an underscore.
-func uprobeSanitizedSymbol(symbol string) string {
-	return rgxUprobeSymbol.ReplaceAllString(symbol, "_")
+// sanitizedSymbol replaces every invalid characted for the tracefs api with an underscore.
+func sanitizedSymbol(symbol string) string {
+	return rgxEventSymbol.ReplaceAllString(symbol, "_")
 }
 
 // uprobeToken creates the PATH:OFFSET(REF_CTR_OFFSET) token for the tracefs api.