link: disable uprobe tests on v4.9

Running v4.9 in vimto, trying to create a perf event via perf_event_open
returns EIO. I've tracked this down to a check in uprobe_register:

    if (!inode->i_mapping->a_ops->readpage && !shmem_mapping(inode->i_mapping))
        return -EIO;

See https://elixir.bootlin.com/linux/v4.9.337/source/kernel/events/uprobes.c#L880

My hunch is that this is related to how vimto sets up the overlayfs mount: if
the probed binary is below the overlayfs the setup fails.

Instead of fixing vimto, stop testing these code paths on v4.9. That kernel
is already EOL so there is not much use in investing more time.

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

link/uprobe_test.go

@@ -69,6 +69,8 @@ func TestExecutableOffset(t *testing.T) {
 }
 
 func TestExecutableLazyLoadSymbols(t *testing.T) {
+	testutils.SkipOnOldKernel(t, "4.14", "uprobe on v4.9 returns EIO on vimto")
+
 	ex, err := OpenExecutable("/bin/bash")
 	qt.Assert(t, qt.IsNil(err))
 	// Addresses must be empty, will be lazy loaded.
@@ -93,6 +95,8 @@ func TestExecutableLazyLoadSymbols(t *testing.T) {
 }
 
 func TestUprobe(t *testing.T) {
+	testutils.SkipOnOldKernel(t, "4.14", "uprobe on v4.9 returns EIO on vimto")
+
 	prog := mustLoadProgram(t, ebpf.Kprobe, 0, "")
 
 	up, err := bashEx.Uprobe(bashSym, prog, nil)
@@ -113,6 +117,8 @@ func TestUprobeExtNotFound(t *testing.T) {
 }
 
 func TestUprobeExtWithOpts(t *testing.T) {
+	testutils.SkipOnOldKernel(t, "4.14", "uprobe on v4.9 returns EIO on vimto")
+
 	prog := mustLoadProgram(t, ebpf.Kprobe, 0, "")
 
 	// NB: It's not possible to invoke the uprobe since we use an arbitrary
@@ -128,6 +134,8 @@ func TestUprobeExtWithOpts(t *testing.T) {
 }
 
 func TestUprobeWithPID(t *testing.T) {
+	testutils.SkipOnOldKernel(t, "4.14", "uprobe on v4.9 returns EIO on vimto")
+
 	prog := mustLoadProgram(t, ebpf.Kprobe, 0, "")
 
 	up, err := bashEx.Uprobe(bashSym, prog, &UprobeOptions{PID: os.Getpid()})
@@ -148,6 +156,8 @@ func TestUprobeWithNonExistentPID(t *testing.T) {
 }
 
 func TestUretprobe(t *testing.T) {
+	testutils.SkipOnOldKernel(t, "4.14", "uprobe on v4.9 returns EIO on vimto")
+
 	prog := mustLoadProgram(t, ebpf.Kprobe, 0, "")
 
 	up, err := bashEx.Uretprobe(bashSym, prog, nil)
@@ -214,6 +224,8 @@ func TestUprobePMUUnavailable(t *testing.T) {
 
 // Test tracefs u(ret)probe creation on all kernel versions.
 func TestUprobeTraceFS(t *testing.T) {
+	testutils.SkipOnOldKernel(t, "4.14", "uprobe on v4.9 returns EIO on vimto")
+
 	// Fetch the offset from the /bin/bash Executable already defined.
 	off, err := bashEx.address(bashSym, 0, 0)
 	qt.Assert(t, qt.IsNil(err))
@@ -265,6 +277,8 @@ func TestUprobeTraceFS(t *testing.T) {
 }
 
 func TestUprobeProgramCall(t *testing.T) {
+	testutils.SkipOnOldKernel(t, "4.14", "uprobe on v4.9 returns EIO on vimto")
+
 	tests := []struct {
 		name string
 		elf  string
@@ -345,6 +359,8 @@ func TestUprobeProgramCall(t *testing.T) {
 }
 
 func TestUprobeProgramWrongPID(t *testing.T) {
+	testutils.SkipOnOldKernel(t, "4.14", "uprobe on v4.9 returns EIO on vimto")
+
 	m, p := newUpdaterMapProg(t, ebpf.Kprobe, 0)
 
 	// Load the '/bin/bash' executable.