link: Allow kprobe multi to be disabled in kernel

Kprobe multi support is gated on CONFIG_FPROBE, without it creating the link fails with ENOTSUP: https://elixir.bootlin.com/linux/latest/source/include/linux/fprobe.h#L56 Unfortunately the standard Debian sid kernel does not have it enabled. Update the kprobe multi test to handle ENOTSUP, and drop the minimum kernel version check, tests otherwise fail with: Feature 'bpf_link_kprobe_multi' isn't supported even though kernel v5.19.11 is newer than v5.18
cilium · Oct 6, 2022 · 7c6a2b2 · 7c6a2b2
1 parent 8fceee5
commit 7c6a2b2
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Showing 3 changed files with 7 additions and 3 deletions.
diff --git a/internal/unix/types_linux.go b/internal/unix/types_linux.go
@@ -24,6 +24,7 @@ const (
 	EFAULT  = linux.EFAULT
 	EACCES  = linux.EACCES
 	EILSEQ  = linux.EILSEQ
+	ENOTSUP = linux.ENOTSUP
 )
 
 const (

diff --git a/internal/unix/types_other.go b/internal/unix/types_other.go
@@ -26,6 +26,7 @@ const (
 	EFAULT
 	EACCES
 	EILSEQ
+	ENOTSUP
 )
 
 // Constants are distinct to avoid breaking switch statements.

diff --git a/link/kprobe_multi.go b/link/kprobe_multi.go
@@ -138,7 +138,7 @@ func (kml *kprobeMultiLink) Unpin() error {
 	return fmt.Errorf("unpin kprobe_multi: %w", ErrNotSupported)
 }
 
-var haveBPFLinkKprobeMulti = internal.FeatureTest("bpf_link_kprobe_multi", "5.18", func() error {
+var haveBPFLinkKprobeMulti = internal.FeatureTest("bpf_link_kprobe_multi", "0.0", func() error {
 	prog, err := ebpf.NewProgram(&ebpf.ProgramSpec{
 		Name: "probe_kpm_link",
 		Type: ebpf.Kprobe,
@@ -167,9 +167,11 @@ var haveBPFLinkKprobeMulti = internal.FeatureTest("bpf_link_kprobe_multi", "5.18
 	if errors.Is(err, unix.EINVAL) {
 		return internal.ErrNotSupported
 	}
-	if err != nil {
-		return err
+	// If CONFIG_FPROBE isn't set.
+	if errors.Is(err, unix.ENOTSUP) {
+		return internal.ErrNotSupported
 	}
+
 	fd.Close()
 
 	return nil
-Original file line number
+Diff line change
@@ Expand Up / @@ -26,6 +26,7 @@ const ( @@
     	EFAULT
     	EACCES
     	EILSEQ
+    	ENOTSUP
     )
     // Constants are distinct to avoid breaking switch statements.
@@ Expand Down @@