netdev - [PATCH bpf-next 3/9] bpf: call verify_insn from its callback in struct bpf_offload

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Date:   Fri,  9 Nov 2018 13:03:26 +0000
From:   Quentin Monnet <quentin.monnet@...ronome.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Cc:     netdev@...r.kernel.org, oss-drivers@...ronome.com,
        Quentin Monnet <quentin.monnet@...ronome.com>
Subject: [PATCH bpf-next 3/9] 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@...ronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
---
 include/linux/bpf.h  | 1 +
 kernel/bpf/offload.c | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c0197c37b2b2..672714cd904f 100644
--- a/include/linux/bpf.h
+++ b/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;
diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
index d513fbf9ca53..2cd3c0d0417b 100644
--- a/kernel/bpf/offload.c
+++ b/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;
-- 
2.17.1