bpf: pass a struct with offload callbacks to bpf_offload_dev_create()

For passing device functions for offloaded eBPF programs, there used to
be no place where to store the pointer without making the non-offloaded
programs pay a memory price.

As a consequence, three functions were called with ndo_bpf() through
specific commands. Now that we have struct bpf_offload_dev, and since
none of those operations rely on RTNL, we can turn these three commands
into hooks inside the struct bpf_prog_offload_ops, and pass them as part
of bpf_offload_dev_create().

This commit effectively passes a pointer to the struct to
bpf_offload_dev_create(). We temporarily have two struct
bpf_prog_offload_ops instances, one under offdev->ops and one under
offload->dev_ops. The next patches will make the transition towards the
former, so that offload->dev_ops can be removed, and callbacks relying
on ndo_bpf() added to offdev->ops as well.

While at it, rename "nfp_bpf_analyzer_ops" as "nfp_bpf_dev_ops" (and
similarly for netdevsim).
Suggested-by: Jakub Kicinski <jakub.kicinski@netronome.com>
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>

drivers/net/ethernet/netronome/nfp/bpf/main.c

@@ -465,7 +465,7 @@ static int nfp_bpf_init(struct nfp_app *app)
 		app->ctrl_mtu = nfp_bpf_ctrl_cmsg_mtu(bpf);
 	}
 
-	bpf->bpf_dev = bpf_offload_dev_create();
+	bpf->bpf_dev = bpf_offload_dev_create(&nfp_bpf_dev_ops);
 	err = PTR_ERR_OR_ZERO(bpf->bpf_dev);
 	if (err)
 		goto err_free_neutral_maps;

drivers/net/ethernet/netronome/nfp/bpf/main.h

@@ -513,7 +513,7 @@ int nfp_verify_insn(struct bpf_verifier_env *env, int insn_idx,
 		    int prev_insn_idx);
 int nfp_bpf_finalize(struct bpf_verifier_env *env);
 
-extern const struct bpf_prog_offload_ops nfp_bpf_analyzer_ops;
+extern const struct bpf_prog_offload_ops nfp_bpf_dev_ops;
 
 struct netdev_bpf;
 struct nfp_app;

drivers/net/ethernet/netronome/nfp/bpf/offload.c

@@ -209,7 +209,7 @@ nfp_bpf_verifier_prep(struct nfp_app *app, struct nfp_net *nn,
 		goto err_free;
 
 	nfp_prog->verifier_meta = nfp_prog_first_meta(nfp_prog);
-	bpf->verifier.ops = &nfp_bpf_analyzer_ops;
+	bpf->verifier.ops = &nfp_bpf_dev_ops;
 
 	return 0;
 
@@ -602,7 +602,7 @@ int nfp_net_bpf_offload(struct nfp_net *nn, struct bpf_prog *prog,
 	return 0;
 }
 
-const struct bpf_prog_offload_ops nfp_bpf_analyzer_ops = {
+const struct bpf_prog_offload_ops nfp_bpf_dev_ops = {
 	.insn_hook	= nfp_verify_insn,
 	.finalize	= nfp_bpf_finalize,
 };

drivers/net/netdevsim/bpf.c

@@ -91,7 +91,7 @@ static int nsim_bpf_finalize(struct bpf_verifier_env *env)
 	return 0;
 }
 
-static const struct bpf_prog_offload_ops nsim_bpf_analyzer_ops = {
+static const struct bpf_prog_offload_ops nsim_bpf_dev_ops = {
 	.insn_hook	= nsim_bpf_verify_insn,
 	.finalize	= nsim_bpf_finalize,
 };
@@ -547,7 +547,7 @@ int nsim_bpf(struct net_device *dev, struct netdev_bpf *bpf)
 		if (err)
 			return err;
 
-		bpf->verifier.ops = &nsim_bpf_analyzer_ops;
+		bpf->verifier.ops = &nsim_bpf_dev_ops;
 		return 0;
 	case BPF_OFFLOAD_TRANSLATE:
 		state = bpf->offload.prog->aux->offload->dev_priv;
@@ -599,7 +599,7 @@ int nsim_bpf_init(struct netdevsim *ns)
 		if (IS_ERR_OR_NULL(ns->sdev->ddir_bpf_bound_progs))
 			return -ENOMEM;
 
-		ns->sdev->bpf_dev = bpf_offload_dev_create();
+		ns->sdev->bpf_dev = bpf_offload_dev_create(&nsim_bpf_dev_ops);
 		err = PTR_ERR_OR_ZERO(ns->sdev->bpf_dev);
 		if (err)
 			return err;

include/linux/bpf.h

@@ -692,7 +692,8 @@ int bpf_map_offload_get_next_key(struct bpf_map *map,
 
 bool bpf_offload_prog_map_match(struct bpf_prog *prog, struct bpf_map *map);
 
-struct bpf_offload_dev *bpf_offload_dev_create(void);
+struct bpf_offload_dev *
+bpf_offload_dev_create(const struct bpf_prog_offload_ops *ops);
 void bpf_offload_dev_destroy(struct bpf_offload_dev *offdev);
 int bpf_offload_dev_netdev_register(struct bpf_offload_dev *offdev,
 				    struct net_device *netdev);

kernel/bpf/offload.c

@@ -33,6 +33,7 @@
 static DECLARE_RWSEM(bpf_devs_lock);
 
 struct bpf_offload_dev {
+	const struct bpf_prog_offload_ops *ops;
 	struct list_head netdevs;
 };
 
@@ -655,7 +656,8 @@ void bpf_offload_dev_netdev_unregister(struct bpf_offload_dev *offdev,
 }
 EXPORT_SYMBOL_GPL(bpf_offload_dev_netdev_unregister);
 
-struct bpf_offload_dev *bpf_offload_dev_create(void)
+struct bpf_offload_dev *
+bpf_offload_dev_create(const struct bpf_prog_offload_ops *ops)
 {
 	struct bpf_offload_dev *offdev;
 	int err;
@@ -673,6 +675,7 @@ struct bpf_offload_dev *bpf_offload_dev_create(void)
 	if (!offdev)
 		return ERR_PTR(-ENOMEM);
 
+	offdev->ops = ops;
 	INIT_LIST_HEAD(&offdev->netdevs);
 
 	return offdev;