bpf: Document cfi_stubs and owner fields in struct bpf_struct_ops

Add missing kernel-doc documentation for the cfi_stubs and owner
fields in struct bpf_struct_ops to fix the following warnings:

  Warning: include/linux/bpf.h:1931 struct member 'cfi_stubs' not
  described in 'bpf_struct_ops'
  Warning: include/linux/bpf.h:1931 struct member 'owner' not
  described in 'bpf_struct_ops'

The cfi_stubs field was added in commit 2cd3e37 ("x86/cfi,bpf:
Fix bpf_struct_ops CFI") to provide CFI stub functions for trampolines,
and the owner field is used for module reference counting.

Signed-off-by: Nirbhay Sharma <[email protected]>
Signed-off-by: Martin KaFai Lau <[email protected]>
Link: https://patch.msgid.link/[email protected]

Author: Nirbhay Sharma

include/linux/bpf.h

@@ -1922,12 +1922,14 @@ struct btf_member;
  *	      reason, if this callback is not defined, the check is skipped as
  *	      the struct_ops map will have final verification performed in
  *	      @reg.
- * @type: BTF type.
- * @value_type: Value type.
+ * @cfi_stubs: Pointer to a structure of stub functions for CFI. These stubs
+ *	       provide the correct Control Flow Integrity hashes for the
+ *	       trampolines generated by BPF struct_ops.
+ * @owner: The module that owns this struct_ops. Used for module reference
+ *	   counting to ensure the module providing the struct_ops cannot be
+ *	   unloaded while in use.
  * @name: The name of the struct bpf_struct_ops object.
  * @func_models: Func models
- * @type_id: BTF type id.
- * @value_id: BTF value id.
  */
 struct bpf_struct_ops {
 	const struct bpf_verifier_ops *verifier_ops;