bpf: call verify_insn from its callback in struct bpf_offload_dev

We intend to remove the dev_ops in struct bpf_prog_offload, and to only
keep the ops in struct bpf_offload_dev instead, which is accessible from
more locations for passing function pointers.

But dev_ops is used for calling the verify_insn hook. Switch to the
newly added ops in struct bpf_prog_offload instead.

To avoid table lookups for each eBPF instruction to verify, we remember
the offdev attached to a netdev and modify bpf_offload_find_netdev() to
avoid performing more than once a lookup for a given offload object.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

include/linux/bpf.h

@@ -273,6 +273,7 @@ struct bpf_prog_offload_ops {
 struct bpf_prog_offload {
 	struct bpf_prog		*prog;
 	struct net_device	*netdev;
+	struct bpf_offload_dev	*offdev;
 	void			*dev_priv;
 	struct list_head	offloads;
 	bool			dev_state;

kernel/bpf/offload.c

@@ -107,6 +107,7 @@ int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr)
 		err = -EINVAL;
 		goto err_unlock;
 	}
+	offload->offdev = ondev->offdev;
 	prog->aux->offload = offload;
 	list_add_tail(&offload->offloads, &ondev->progs);
 	dev_put(offload->netdev);
@@ -167,7 +168,8 @@ int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env,
 	down_read(&bpf_devs_lock);
 	offload = env->prog->aux->offload;
 	if (offload)
-		ret = offload->dev_ops->insn_hook(env, insn_idx, prev_insn_idx);
+		ret = offload->offdev->ops->insn_hook(env, insn_idx,
+						      prev_insn_idx);
 	up_read(&bpf_devs_lock);
 
 	return ret;