link: test - attach k(ret)probe to optimized kernel symbols containin…

…g dots

These are all local symbols that visible in /proc/kallsyms and traceable
by kprobes. Make sure the library supports attaching to these.

Signed-off-by: Timo Beckers <timo@isovalent.com>

link/kprobe_test.go

@@ -13,43 +13,72 @@ import (
 	"github.com/cilium/ebpf/internal/unix"
 )
 
-// Kernel symbol that should be present on all tested kernels.
+// Global symbol, present on all tested kernels.
 var ksym = "vprintk"
 
-func TestKprobe(t *testing.T) {
-	c := qt.New(t)
+// Collection of various symbols present in all tested kernels.
+// Compiler optimizations result in different names for these symbols.
+var symTests = []string{
+	"async_resume.cold",         // marked with 'cold' gcc attribute, unlikely to be executed
+	"echo_char.isra.0",          // function optimized by -fipa-sra
+	"get_buffer.constprop.0",    // optimized function with constant operands
+	"unregister_kprobes.part.0", // function body that was split and partially inlined
+}
 
+func TestKprobe(t *testing.T) {
 	prog := mustLoadProgram(t, ebpf.Kprobe, 0, "")
 
-	k, err := Kprobe(ksym, prog, nil)
-	c.Assert(err, qt.IsNil)
-	defer k.Close()
+	for _, tt := range symTests {
+		t.Run(tt, func(t *testing.T) {
+			k, err := Kprobe(tt, prog, nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer k.Close()
+		})
+	}
 
-	testLink(t, k, prog)
+	c := qt.New(t)
 
-	k, err = Kprobe("bogus", prog, nil)
-	c.Assert(errors.Is(err, os.ErrNotExist), qt.IsTrue, qt.Commentf("got error: %s", err))
+	k, err := Kprobe("bogus", prog, nil)
+	c.Assert(err, qt.ErrorIs, os.ErrNotExist, qt.Commentf("got error: %s", err))
 	if k != nil {
 		k.Close()
 	}
+
+	k, err = Kprobe(ksym, prog, nil)
+	c.Assert(err, qt.IsNil)
+	defer k.Close()
+
+	testLink(t, k, prog)
 }
 
 func TestKretprobe(t *testing.T) {
-	c := qt.New(t)
-
 	prog := mustLoadProgram(t, ebpf.Kprobe, 0, "")
 
-	k, err := Kretprobe(ksym, prog, nil)
-	c.Assert(err, qt.IsNil)
-	defer k.Close()
+	for _, tt := range symTests {
+		t.Run(tt, func(t *testing.T) {
+			k, err := Kretprobe(tt, prog, nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer k.Close()
+		})
+	}
 
-	testLink(t, k, prog)
+	c := qt.New(t)
 
-	k, err = Kretprobe("bogus", prog, nil)
-	c.Assert(errors.Is(err, os.ErrNotExist), qt.IsTrue, qt.Commentf("got error: %s", err))
+	k, err := Kretprobe("bogus", prog, nil)
+	c.Assert(err, qt.ErrorIs, os.ErrNotExist, qt.Commentf("got error: %s", err))
 	if k != nil {
 		k.Close()
 	}
+
+	k, err = Kretprobe(ksym, prog, nil)
+	c.Assert(err, qt.IsNil)
+	defer k.Close()
+
+	testLink(t, k, prog)
 }
 
 func TestKprobeErrors(t *testing.T) {

link/link_test.go

@@ -97,7 +97,7 @@ func testLink(t *testing.T, link Link, prog *ebpf.Program) {
 	}
 	defer os.RemoveAll(tmp)
 
-	t.Run("pinning", func(t *testing.T) {
+	t.Run("link/pinning", func(t *testing.T) {
 		path := filepath.Join(tmp, "link")
 		err = link.Pin(path)
 		testutils.SkipIfNotSupported(t, err)
@@ -123,7 +123,7 @@ func testLink(t *testing.T, link Link, prog *ebpf.Program) {
 		}
 	})
 
-	t.Run("update", func(t *testing.T) {
+	t.Run("link/update", func(t *testing.T) {
 		err := link.Update(prog)
 		testutils.SkipIfNotSupported(t, err)
 		if err != nil {
@@ -142,7 +142,7 @@ func testLink(t *testing.T, link Link, prog *ebpf.Program) {
 		}()
 	})
 
-	t.Run("link_info", func(t *testing.T) {
+	t.Run("link/info", func(t *testing.T) {
 		info, err := link.Info()
 		testutils.SkipIfNotSupported(t, err)
 		if err != nil {