program: add benchmark

Add a benchmark which excercises two complicated code paths:
finding a function in the kernel to attach to, and resolving a
reference to a kfunc.

Both currently force a new parse of vmlinux BTF which is why
this is excruciatingly slow.

Signed-off-by: Lorenz Bauer <lmb@isovalent.com>

prog_test.go

@@ -928,6 +928,22 @@ func TestProgramInstructions(t *testing.T) {
 	}
 }
 
+func BenchmarkNewProgram(b *testing.B) {
+	testutils.SkipOnOldKernel(b, "5.18", "kfunc support")
+	spec, err := LoadCollectionSpec(fmt.Sprintf("testdata/kfunc-%s.elf", internal.ClangEndian))
+	qt.Assert(b, err, qt.IsNil)
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		_, err := NewProgram(spec.Programs["benchmark"])
+		if !errors.Is(err, unix.EACCES) {
+			b.Fatal("Unexpected error:", err)
+		}
+	}
+}
+
 func createProgramArray(t *testing.T) *Map {
 	t.Helper()
 

testdata/kfunc.c

@@ -20,3 +20,12 @@ __section("tc") int call_kfunc(void *ctx) {
 	}
 	return 1;
 }
+
+extern int bpf_fentry_test1(int) __ksym;
+
+__section("fentry/bpf_fentry_test2") int benchmark() {
+	// bpf_fentry_test1 is a valid kfunc but not allowed to be called from
+	// TC context. We use this to avoid loading a gajillion programs into
+	// the kernel when benchmarking the loader.
+	return bpf_fentry_test1(0);
+}