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Message-Id: <20180809194220.17484-1-daniel@iogearbox.net>
Date: Thu, 9 Aug 2018 21:42:20 +0200
From: Daniel Borkmann <daniel@...earbox.net>
To: ast@...nel.org
Cc: netdev@...r.kernel.org, yhs@...com,
Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH bpf-next] bpf: enable btf for use in all maps
Commit a26ca7c982cb ("bpf: btf: Add pretty print support to
the basic arraymap") enabled support for BTF and dumping via
BPF fs for arraymap. However, both can be decoupled from each
other such that all BPF maps can be supported for attaching
BTF key/value information, while not all maps necessarily
need to dump via map_seq_show_elem() callback.
The check in array_map_check_btf() can be generalized as
ultimatively the key and value size is the only contraint
that needs to match for the map. The fact that the key needs
to be of type int is optional; it could be any data type as
long as it matches the 4 byte key size, just like hash table
key or others could be of any data type as well.
Minimal example of a hash table dump which then works out
of the box for bpftool:
# bpftool map dump id 19
[{
"key": {
"": {
"vip": 0,
"vipv6": []
},
"port": 0,
"family": 0,
"proto": 0
},
"value": {
"flags": 0,
"vip_num": 0
}
}
]
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Cc: Yonghong Song <yhs@...com>
---
include/linux/bpf.h | 4 +---
kernel/bpf/arraymap.c | 27 ---------------------------
kernel/bpf/inode.c | 3 ++-
kernel/bpf/syscall.c | 24 ++++++++++++++++++++----
4 files changed, 23 insertions(+), 35 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index cd8790d..eb76e8e 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -48,8 +48,6 @@ struct bpf_map_ops {
u32 (*map_fd_sys_lookup_elem)(void *ptr);
void (*map_seq_show_elem)(struct bpf_map *map, void *key,
struct seq_file *m);
- int (*map_check_btf)(const struct bpf_map *map, const struct btf *btf,
- u32 key_type_id, u32 value_type_id);
};
struct bpf_map {
@@ -118,7 +116,7 @@ static inline bool bpf_map_offload_neutral(const struct bpf_map *map)
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;
+ return map->btf && map->ops->map_seq_show_elem;
}
extern const struct bpf_map_ops bpf_map_offload_ops;
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 2aa55d030..67f0bdf 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -358,32 +358,6 @@ static void array_map_seq_show_elem(struct bpf_map *map, void *key,
rcu_read_unlock();
}
-static int array_map_check_btf(const struct bpf_map *map, const struct btf *btf,
- u32 btf_key_id, u32 btf_value_id)
-{
- const struct btf_type *key_type, *value_type;
- u32 key_size, value_size;
- u32 int_data;
-
- key_type = btf_type_id_size(btf, &btf_key_id, &key_size);
- if (!key_type || BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
- return -EINVAL;
-
- int_data = *(u32 *)(key_type + 1);
- /* bpf array can only take a u32 key. This check makes
- * sure that the btf matches the attr used during map_create.
- */
- if (BTF_INT_BITS(int_data) != 32 || key_size != 4 ||
- BTF_INT_OFFSET(int_data))
- return -EINVAL;
-
- value_type = btf_type_id_size(btf, &btf_value_id, &value_size);
- if (!value_type || value_size != map->value_size)
- return -EINVAL;
-
- return 0;
-}
-
const struct bpf_map_ops array_map_ops = {
.map_alloc_check = array_map_alloc_check,
.map_alloc = array_map_alloc,
@@ -394,7 +368,6 @@ const struct bpf_map_ops array_map_ops = {
.map_delete_elem = array_map_delete_elem,
.map_gen_lookup = array_map_gen_lookup,
.map_seq_show_elem = array_map_seq_show_elem,
- .map_check_btf = array_map_check_btf,
};
const struct bpf_map_ops percpu_array_map_ops = {
diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 76efe9a..400f27d 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -332,7 +332,8 @@ static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg)
struct bpf_map *map = arg;
return bpf_mkobj_ops(dentry, mode, arg, &bpf_map_iops,
- map->btf ? &bpffs_map_fops : &bpffs_obj_fops);
+ bpf_map_support_seq_show(map) ?
+ &bpffs_map_fops : &bpffs_obj_fops);
}
static struct dentry *
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 5af4e9e..0b6f6e8 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -455,6 +455,23 @@ static int bpf_obj_name_cpy(char *dst, const char *src)
return 0;
}
+static int map_check_btf(const struct bpf_map *map, const struct btf *btf,
+ u32 btf_key_id, u32 btf_value_id)
+{
+ const struct btf_type *key_type, *value_type;
+ u32 key_size, value_size;
+
+ key_type = btf_type_id_size(btf, &btf_key_id, &key_size);
+ if (!key_type || key_size != map->key_size)
+ return -EINVAL;
+
+ value_type = btf_type_id_size(btf, &btf_value_id, &value_size);
+ if (!value_type || value_size != map->value_size)
+ return -EINVAL;
+
+ return 0;
+}
+
#define BPF_MAP_CREATE_LAST_FIELD btf_value_type_id
/* called via syscall */
static int map_create(union bpf_attr *attr)
@@ -489,8 +506,7 @@ static int map_create(union bpf_attr *attr)
atomic_set(&map->refcnt, 1);
atomic_set(&map->usercnt, 1);
- if (bpf_map_support_seq_show(map) &&
- (attr->btf_key_type_id || attr->btf_value_type_id)) {
+ if (attr->btf_key_type_id || attr->btf_value_type_id) {
struct btf *btf;
if (!attr->btf_key_type_id || !attr->btf_value_type_id) {
@@ -504,8 +520,8 @@ static int map_create(union bpf_attr *attr)
goto free_map_nouncharge;
}
- err = map->ops->map_check_btf(map, btf, attr->btf_key_type_id,
- attr->btf_value_type_id);
+ err = map_check_btf(map, btf, attr->btf_key_type_id,
+ attr->btf_value_type_id);
if (err) {
btf_put(btf);
goto free_map_nouncharge;
--
2.9.5
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