Do kprobe.multi on addresses instead of symbols

As Martynas P. suggests, it's better to use func addrs instead of symbols
for `kprobe.multi`.

Signed-off-by: Leon Hwang <hffilwlqm@gmail.com>

internal/pwru/ksym.go

@@ -22,6 +22,7 @@ func (a byAddr) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
 type Addr2Name struct {
 	Addr2NameMap   map[uint64]*ksym
 	Addr2NameSlice []*ksym
+	Name2AddrMap   map[string][]uintptr
 }
 
 func (a *Addr2Name) findNearestSym(ip uint64) string {
@@ -44,6 +45,7 @@ func (a *Addr2Name) findNearestSym(ip uint64) string {
 func GetAddrs(funcs Funcs, all bool) (Addr2Name, error) {
 	a2n := Addr2Name{
 		Addr2NameMap: make(map[uint64]*ksym),
+		Name2AddrMap: make(map[string][]uintptr),
 	}
 
 	file, err := os.Open("/proc/kallsyms")
@@ -66,6 +68,7 @@ func GetAddrs(funcs Funcs, all bool) (Addr2Name, error) {
 				name: name,
 			}
 			a2n.Addr2NameMap[addr] = sym
+			a2n.Name2AddrMap[name] = append(a2n.Name2AddrMap[name], uintptr(addr))
 			if all {
 				a2n.Addr2NameSlice = append(a2n.Addr2NameSlice, sym)
 			}

main.go

@@ -295,14 +295,25 @@ func main() {
 			default:
 			}
 
-			opts := link.KprobeMultiOptions{Symbols: funcsByPos[pos]}
+			addrs := make([]uintptr, 0, len(fns))
+			for _, fn := range fns {
+				if addr, ok := addr2name.Name2AddrMap[fn]; ok {
+					addrs = append(addrs, addr...)
+				} else {
+					ignored += 1
+					bar.Increment()
+					continue
+				}
+			}
+
+			if len(addrs) == 0 {
+				continue
+			}
+
+			opts := link.KprobeMultiOptions{Addresses: addrs}
 			kp, err := link.KprobeMulti(fn, opts)
 			bar.Add(len(fns))
 			if err != nil {
-				if errors.Is(err, syscall.EADDRNOTAVAIL) {
-					log.Fatalf("Found duplicate function name in the kernel (%s). Set --backend=kprobe to fix the loading error until https://github.com/cilium/pwru/issues/284 has been fixed",
-						err)
-				}
 				log.Fatalf("Opening kprobe-multi for pos %d: %s\n", pos, err)
 			}
 			kprobes = append(kprobes, kp)