link: Allow kprobe multi to be disabled in kernel

Kprobe multi support is gated on CONFIG_FPROBE, without it creating the link fails with EOPNOTSUPP: https://elixir.bootlin.com/linux/v6.0.3/source/include/linux/fprobe.h#L64 Unfortunately the standard Debian sid kernel does not have it enabled. Update the kprobe multi test to handle EOPNOTSUPP. Co-developed-by: Lorenz Bauer <i@lmb.io>
cilium · Oct 21, 2022 · 447495b · 447495b
1 parent cd71a9c
commit 447495b
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Showing 3 changed files with 24 additions and 18 deletions.
diff --git a/internal/unix/types_linux.go b/internal/unix/types_linux.go
@@ -9,21 +9,22 @@ import (
 )
 
 const (
-	ENOENT  = linux.ENOENT
-	EEXIST  = linux.EEXIST
-	EAGAIN  = linux.EAGAIN
-	ENOSPC  = linux.ENOSPC
-	EINVAL  = linux.EINVAL
-	EPOLLIN = linux.EPOLLIN
-	EINTR   = linux.EINTR
-	EPERM   = linux.EPERM
-	ESRCH   = linux.ESRCH
-	ENODEV  = linux.ENODEV
-	EBADF   = linux.EBADF
-	E2BIG   = linux.E2BIG
-	EFAULT  = linux.EFAULT
-	EACCES  = linux.EACCES
-	EILSEQ  = linux.EILSEQ
+	ENOENT     = linux.ENOENT
+	EEXIST     = linux.EEXIST
+	EAGAIN     = linux.EAGAIN
+	ENOSPC     = linux.ENOSPC
+	EINVAL     = linux.EINVAL
+	EPOLLIN    = linux.EPOLLIN
+	EINTR      = linux.EINTR
+	EPERM      = linux.EPERM
+	ESRCH      = linux.ESRCH
+	ENODEV     = linux.ENODEV
+	EBADF      = linux.EBADF
+	E2BIG      = linux.E2BIG
+	EFAULT     = linux.EFAULT
+	EACCES     = linux.EACCES
+	EILSEQ     = linux.EILSEQ
+	EOPNOTSUPP = linux.EOPNOTSUPP
 )
 
 const (

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

diff --git a/link/kprobe_multi.go b/link/kprobe_multi.go
@@ -164,12 +164,16 @@ var haveBPFLinkKprobeMulti = internal.FeatureTest("bpf_link_kprobe_multi", "5.18
 		Count:      1,
 		Syms:       sys.NewStringSlicePointer([]string{"vprintk"}),
 	})
-	if errors.Is(err, unix.EINVAL) {
+	switch {
+	case errors.Is(err, unix.EINVAL):
 		return internal.ErrNotSupported
-	}
-	if err != nil {
+	// If CONFIG_FPROBE isn't set.
+	case errors.Is(err, unix.EOPNOTSUPP):
+		return internal.ErrNotSupported
+	case err != nil:
 		return err
 	}
+
 	fd.Close()
 
 	return nil
-Original file line number
+Diff line change
@@ Expand Up / @@ -26,6 +26,7 @@ const ( @@
     	EFAULT
     	EACCES
     	EILSEQ
+    	EOPNOTSUPP
     )
     // Constants are distinct to avoid breaking switch statements.
@@ Expand Down @@