This patch adds pretty print support to the basic arraymap.
Support for other bpf maps can be added later.
This patch adds new attrs to the BPF_MAP_CREATE command to allow
specifying the btf_fd, btf_key_id and btf_value_id. The
BPF_MAP_CREATE can then associate the btf to the map if
the creating map supports BTF.
A BTF supported map needs to implement two new map ops,
map_seq_show_elem() and map_check_btf(). This patch has
implemented these new map ops for the basic arraymap.
It also adds file_operations to the pinned map
such that the pinned map can be opened and read.
Here is a sample output when reading a pinned arraymap
with the following map's value:
struct map_value {
int count_a;
int count_b;
};
cat /sys/fs/bpf/pinned_array_map:
0: {1,2}
1: {3,4}
2: {5,6}
...
Signed-off-by: Martin KaFai Lau <ka...@fb.com>
Acked-by: Alexei Starovoitov <a...@fb.com>
---
include/linux/bpf.h | 20 ++++++-
include/uapi/linux/bpf.h | 3 +
kernel/bpf/arraymap.c | 50 ++++++++++++++++
kernel/bpf/inode.c | 146 ++++++++++++++++++++++++++++++++++++++++++++++-
kernel/bpf/syscall.c | 32 ++++++++++-
5 files changed, 244 insertions(+), 7 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 819229c80eca..277d4bfc56c1 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -22,6 +22,8 @@ struct perf_event;
struct bpf_prog;
struct bpf_map;
struct sock;
+struct seq_file;
+struct btf;
/* map is generic key/value storage optionally accesible by eBPF programs */
struct bpf_map_ops {
@@ -43,10 +45,14 @@ struct bpf_map_ops {
void (*map_fd_put_ptr)(void *ptr);
u32 (*map_gen_lookup)(struct bpf_map *map, struct bpf_insn *insn_buf);
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 {
- /* 1st cacheline with read-mostly members of which some
+ /* The first two cachelines with read-mostly members of which some
* are also accessed in fast-path (e.g. ops, max_entries).
*/
const struct bpf_map_ops *ops ____cacheline_aligned;
@@ -62,10 +68,13 @@ struct bpf_map {
u32 pages;
u32 id;
int numa_node;
+ u32 btf_key_id;
+ u32 btf_value_id;
+ struct btf *btf;
bool unpriv_array;
- /* 7 bytes hole */
+ /* 55 bytes hole */
- /* 2nd cacheline with misc members to avoid false sharing
+ /* The 3rd and 4th cacheline with misc members to avoid false sharing
* particularly with refcounting.
*/
struct user_struct *user ____cacheline_aligned;
@@ -100,6 +109,11 @@ 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_support_seq_show(const struct bpf_map *map)
+{
+ return map->ops->map_seq_show_elem && map->ops->map_check_btf;
+}
+
extern const struct bpf_map_ops bpf_map_offload_ops;
/* function argument constraints */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 72d3516d4677..9c0d5cfbcb19 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -273,6 +273,9 @@ union bpf_attr {
*/
char map_name[BPF_OBJ_NAME_LEN];
__u32 map_ifindex; /* ifindex of netdev to create on */
+ __u32 btf_fd; /* fd pointing to a BTF type data */
+ __u32 btf_key_id; /* BTF type_id of the key */
+ __u32 btf_value_id; /* BTF type_id of the value */
};
struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 14750e7c5ee4..02a189339381 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -11,11 +11,13 @@
* General Public License for more details.
*/
#include <linux/bpf.h>
+#include <linux/btf.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/filter.h>
#include <linux/perf_event.h>
+#include <uapi/linux/btf.h>
#include "map_in_map.h"
@@ -336,6 +338,52 @@ static void array_map_free(struct bpf_map *map)
bpf_map_area_free(array);
}
+static void array_map_seq_show_elem(struct bpf_map *map, void *key,
+ struct seq_file *m)
+{
+ void *value;
+
+ rcu_read_lock();
+
+ value = array_map_lookup_elem(map, key);
+ if (!value) {
+ rcu_read_unlock();
+ return;
+ }
+
+ seq_printf(m, "%u: ", *(u32 *)key);
+ btf_type_seq_show(map->btf, map->btf_value_id, value, m);
+ seq_puts(m, "\n");
+
+ 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,
@@ -345,6 +393,8 @@ const struct bpf_map_ops array_map_ops = {
.map_update_elem = array_map_update_elem,
.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 bf6da59ae0d0..11ea64bcc9d9 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -150,8 +150,144 @@ static int bpf_mkdir(struct inode *dir, struct dentry
*dentry, umode_t mode)
return 0;
}
+struct map_iter {
+ void *key;
+ bool done;
+};
+
+static struct map_iter *map_iter(struct seq_file *m)
+{
+ return m->private;
+}
+
+static struct bpf_map *seq_file_to_map(struct seq_file *m)
+{
+ return file_inode(m->file)->i_private;
+}
+
+static void map_iter_free(struct map_iter *iter)
+{
+ if (iter) {
+ kfree(iter->key);
+ kfree(iter);
+ }
+}
+
+static struct map_iter *map_iter_alloc(struct bpf_map *map)
+{
+ struct map_iter *iter;
+
+ iter = kzalloc(sizeof(*iter), GFP_KERNEL | __GFP_NOWARN);
+ if (!iter)
+ goto error;
+
+ iter->key = kzalloc(map->key_size, GFP_KERNEL | __GFP_NOWARN);
+ if (!iter->key)
+ goto error;
+
+ return iter;
+
+error:
+ map_iter_free(iter);
+ return NULL;
+}
+
+void *map_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ struct bpf_map *map = seq_file_to_map(m);
+ void *key = map_iter(m)->key;
+
+ if (map_iter(m)->done)
+ return NULL;
+
+ if (unlikely(v == SEQ_START_TOKEN))
+ goto done;
+
+ if (map->ops->map_get_next_key(map, key, key)) {
+ map_iter(m)->done = true;
+ return NULL;
+ }
+
+done:
+ ++(*pos);
+ return key;
+}
+
+static void *map_seq_start(struct seq_file *m, loff_t *pos)
+{
+ if (map_iter(m)->done)
+ return NULL;
+
+ return *pos ? map_iter(m)->key : SEQ_START_TOKEN;
+}
+
+static void map_seq_stop(struct seq_file *m, void *v)
+{
+}
+
+static int map_seq_show(struct seq_file *m, void *v)
+{
+ struct bpf_map *map = seq_file_to_map(m);
+ void *key = map_iter(m)->key;
+
+ if (unlikely(v == SEQ_START_TOKEN)) {
+ seq_puts(m, "# WARNING!! The output is for debug purpose
only\n");
+ seq_puts(m, "# WARNING!! The output format will change\n");
+ } else {
+ map->ops->map_seq_show_elem(map, key, m);
+ }
+
+ return 0;
+}
+
+static const struct seq_operations bpffs_map_seq_ops = {
+ .start = map_seq_start,
+ .next = map_seq_next,
+ .show = map_seq_show,
+ .stop = map_seq_stop,
+};
+
+static int bpffs_map_open(struct inode *inode, struct file *file)
+{
+ struct bpf_map *map = inode->i_private;
+ struct map_iter *iter;
+ struct seq_file *m;
+ int err;
+
+ iter = map_iter_alloc(map);
+ if (!iter)
+ return -ENOMEM;
+
+ err = seq_open(file, &bpffs_map_seq_ops);
+ if (err) {
+ map_iter_free(iter);
+ return err;
+ }
+
+ m = file->private_data;
+ m->private = iter;
+
+ return 0;
+}
+
+static int bpffs_map_release(struct inode *inode, struct file *file)
+{
+ struct seq_file *m = file->private_data;
+
+ map_iter_free(map_iter(m));
+
+ return seq_release(inode, file);
+}
+
+const struct file_operations bpffs_map_fops = {
+ .open = bpffs_map_open,
+ .read = seq_read,
+ .release = bpffs_map_release,
+};
+
static int bpf_mkobj_ops(struct dentry *dentry, umode_t mode, void *raw,
- const struct inode_operations *iops)
+ const struct inode_operations *iops,
+ const struct file_operations *fops)
{
struct inode *dir = dentry->d_parent->d_inode;
struct inode *inode = bpf_get_inode(dir->i_sb, dir, mode);
@@ -159,6 +295,7 @@ static int bpf_mkobj_ops(struct dentry *dentry, umode_t
mode, void *raw,
return PTR_ERR(inode);
inode->i_op = iops;
+ inode->i_fop = fops;
inode->i_private = raw;
bpf_dentry_finalize(dentry, inode, dir);
@@ -167,12 +304,15 @@ static int bpf_mkobj_ops(struct dentry *dentry, umode_t
mode, void *raw,
static int bpf_mkprog(struct dentry *dentry, umode_t mode, void *arg)
{
- return bpf_mkobj_ops(dentry, mode, arg, &bpf_prog_iops);
+ return bpf_mkobj_ops(dentry, mode, arg, &bpf_prog_iops, NULL);
}
static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg)
{
- return bpf_mkobj_ops(dentry, mode, arg, &bpf_map_iops);
+ struct bpf_map *map = arg;
+
+ return bpf_mkobj_ops(dentry, mode, arg, &bpf_map_iops,
+ map->btf ? &bpffs_map_fops : NULL);
}
static struct dentry *
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 678d90b12698..ecf6200cc6f2 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -27,6 +27,7 @@
#include <linux/cred.h>
#include <linux/timekeeping.h>
#include <linux/ctype.h>
+#include <linux/btf.h>
#define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PROG_ARRAY || \
(map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \
@@ -251,6 +252,7 @@ static void bpf_map_free_deferred(struct work_struct *work)
bpf_map_uncharge_memlock(map);
security_bpf_map_free(map);
+ btf_put(map->btf);
/* implementation dependent freeing */
map->ops->map_free(map);
}
@@ -416,7 +418,7 @@ static int bpf_obj_name_cpy(char *dst, const char *src)
return 0;
}
-#define BPF_MAP_CREATE_LAST_FIELD map_ifindex
+#define BPF_MAP_CREATE_LAST_FIELD btf_value_id
/* called via syscall */
static int map_create(union bpf_attr *attr)
{
@@ -454,6 +456,33 @@ static int map_create(union bpf_attr *attr)
if (err)
goto free_map_nouncharge;
+ if (bpf_map_support_seq_show(map) &&
+ (attr->btf_key_id || attr->btf_value_id)) {
+ struct btf *btf;
+
+ if (!attr->btf_key_id || !attr->btf_value_id) {
+ err = -EINVAL;
+ goto free_map_nouncharge;
+ }
+
+ btf = btf_get_by_fd(attr->btf_fd);
+ if (IS_ERR(btf)) {
+ err = PTR_ERR(btf);
+ goto free_map_nouncharge;
+ }
+
+ err = map->ops->map_check_btf(map, btf, attr->btf_key_id,
+ attr->btf_value_id);
+ if (err) {
+ btf_put(btf);
+ goto free_map_nouncharge;
+ }
+
+ map->btf = btf;
+ map->btf_key_id = attr->btf_key_id;
+ map->btf_value_id = attr->btf_value_id;
+ }
+
err = bpf_map_charge_memlock(map);
if (err)
goto free_map_sec;
@@ -482,6 +511,7 @@ static int map_create(union bpf_attr *attr)
free_map_sec:
security_bpf_map_free(map);
free_map_nouncharge:
+ btf_put(map->btf);
map->ops->map_free(map);
return err;
}
--
2.9.5
