netdev - [PATCH bpf-next 01/10] bpf: offload: allow offloaded programs to use perf event arrays

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Date:   Thu,  3 May 2018 18:37:08 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     alexei.starovoitov@...il.com, daniel@...earbox.net
Cc:     oss-drivers@...ronome.com, netdev@...r.kernel.org,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [PATCH bpf-next 01/10] bpf: offload: allow offloaded programs to use perf event arrays

BPF_MAP_TYPE_PERF_EVENT_ARRAY is special as far as offload goes.
The map only holds glue to perf ring, not actual data.  Allow
non-offloaded perf event arrays to be used in offloaded programs.
Offload driver can extract the events from HW and put them in
the map for user space to retrieve.

Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@...ronome.com>
Reviewed-by: Jiong Wang <jiong.wang@...ronome.com>
---
 include/linux/bpf.h  | 5 +++++
 kernel/bpf/offload.c | 6 ++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c553f6f9c6b0..9d68bb665cb2 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -110,6 +110,11 @@ static inline struct bpf_offloaded_map *map_to_offmap(struct bpf_map *map)
 	return container_of(map, struct bpf_offloaded_map, map);
 }
 
+static inline bool bpf_map_offload_neutral(const struct bpf_map *map)
+{
+	return map->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY;
+}
+
 static inline bool bpf_map_support_seq_show(const struct bpf_map *map)
 {
 	return map->ops->map_seq_show_elem && map->ops->map_check_btf;
diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
index c9401075b58c..ac747d5cf7c6 100644
--- a/kernel/bpf/offload.c
+++ b/kernel/bpf/offload.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2017 Netronome Systems, Inc.
+ * Copyright (C) 2017-2018 Netronome Systems, Inc.
  *
  * This software is licensed under the GNU General License Version 2,
  * June 1991 as shown in the file COPYING in the top-level directory of this
@@ -474,8 +474,10 @@ bool bpf_offload_dev_match(struct bpf_prog *prog, struct bpf_map *map)
 	struct bpf_prog_offload *offload;
 	bool ret;
 
-	if (!bpf_prog_is_dev_bound(prog->aux) || !bpf_map_is_dev_bound(map))
+	if (!bpf_prog_is_dev_bound(prog->aux))
 		return false;
+	if (!bpf_map_is_dev_bound(map))
+		return bpf_map_offload_neutral(map);
 
 	down_read(&bpf_devs_lock);
 	offload = prog->aux->offload;
-- 
2.17.0