bpflbr: Output verbose log

Signed-off-by: Leon Hwang <[email protected]>

internal/bpflbr/bpf_tracing.go

@@ -5,6 +5,7 @@ package bpflbr
 
 import (
 	"fmt"
+	"log"
 	"sync"
 
 	"github.com/cilium/ebpf"
@@ -96,6 +97,10 @@ func (t *bpfTracing) traceProg(spec *ebpf.CollectionSpec, reusedMaps map[string]
 		return fmt.Errorf("failed to attach tracing: %w", err)
 	}
 
+	if verbose {
+		log.Printf("Tracing %s of prog %v", info.funcName, info.prog)
+	}
+
 	t.llock.Lock()
 	t.progs = append(t.progs, cloned)
 	t.links = append(t.links, l)

internal/bpflbr/flags.go

@@ -20,6 +20,8 @@ const (
 	progFlagDescriptorName   = "name"
 )
 
+var verbose bool
+
 type ProgFlag struct {
 	progID uint32
 	pinned string
@@ -109,6 +111,7 @@ func ParseFlags() (*Flags, error) {
 	f.StringSliceVarP(&flags.progs, "prog", "p", nil, "bpf prog info for bpflbr in format PROG[,PROG,..], PROG: PROGID[:<prog function name>], PROGID: <prog ID> or 'i/id:<prog ID>' or 'p/pinned:<pinned file>' or 't/tag:<prog tag>' or 'n/name:<prog full name>'; all bpf progs will be traced by default")
 	f.StringVarP(&flags.outputFile, "output", "o", "", "output file for the result, default is stdout")
 	f.BoolVar(&flags.dumpProg, "dump-jited", false, "dump native insn info of bpf prog, the one bpf prog must be provided by --prog (its function name will be ignored)")
+	f.BoolVarP(&verbose, "verbose", "v", false, "output verbose log")
 
 	return &flags, f.Parse(os.Args)
 }

internal/bpflbr/lbr.go

@@ -61,7 +61,7 @@ func Run(reader *ringbuf.Reader, progs *bpfProgs, addr2line *Addr2Line, ksyms *K
 			continue
 		}
 
-		foundEntries := false
+		foundEntries := verbose
 		nrEntries := event.NrBytes / int64(8*3)
 		lbrEntries := make([]branchEntry, 0, nrEntries)
 		for i := 0; i < int(nrEntries); i++ {