Commit e8d2bec0 authored by Daniel Borkmann's avatar Daniel Borkmann
Browse files

bpf: decouple btf from seq bpf fs dump and enable more maps 



Commit a26ca7c9 ("bpf: btf: Add pretty print support to
the basic arraymap") and 699c86d6 ("bpf: btf: add pretty
print for hash/lru_hash maps") enabled support for BTF and
dumping via BPF fs for array and hash/lru map. However, both
can be decoupled from each other such that regular 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 basic sanity check which is a prerequisite for all maps
is that key/value size has to match in any case, and some maps
can have extra checks via map_check_btf() callback, e.g.
probing certain types or indicating no support in general. With
that we can also enable retrieving BTF info for per-cpu map
types and lpm.

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
parent 9d6f4177

include/linux/bpf.h

+9 −4
Original line number Diff line number Diff line
@@ -23,7 +23,7 @@ struct bpf_prog; 
struct bpf_map;

struct sock;

struct seq_file;

struct btf;

struct btf_type;



/* map is generic key/value storage optionally accesible by eBPF programs */

struct bpf_map_ops {
@@ -48,8 +48,9 @@ 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);

	int (*map_check_btf)(const struct bpf_map *map,

			     const struct btf_type *key_type,

			     const struct btf_type *value_type);

};



struct bpf_map {
@@ -118,9 +119,13 @@ 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;

}



int map_check_no_btf(const struct bpf_map *map,

		     const struct btf_type *key_type,

		     const struct btf_type *value_type);



extern const struct bpf_map_ops bpf_map_offload_ops;



/* function argument constraints */

kernel/bpf/arraymap.c

+12 −14
Original line number Diff line number Diff line
@@ -358,27 +358,20 @@ 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)

static int array_map_check_btf(const struct bpf_map *map,

			       const struct btf_type *key_type,

			       const struct btf_type *value_type)

{

	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)

	if (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.

	/* 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)

	if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data))

		return -EINVAL;



	return 0;
@@ -405,6 +398,7 @@ const struct bpf_map_ops percpu_array_map_ops = { 
	.map_lookup_elem = percpu_array_map_lookup_elem,

	.map_update_elem = array_map_update_elem,

	.map_delete_elem = array_map_delete_elem,

	.map_check_btf = array_map_check_btf,

};



static int fd_array_map_alloc_check(union bpf_attr *attr)
@@ -546,6 +540,7 @@ const struct bpf_map_ops prog_array_map_ops = { 
	.map_fd_put_ptr = prog_fd_array_put_ptr,

	.map_fd_sys_lookup_elem = prog_fd_array_sys_lookup_elem,

	.map_release_uref = bpf_fd_array_map_clear,

	.map_check_btf = map_check_no_btf,

};



static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file,
@@ -634,6 +629,7 @@ const struct bpf_map_ops perf_event_array_map_ops = { 
	.map_fd_get_ptr = perf_event_fd_array_get_ptr,

	.map_fd_put_ptr = perf_event_fd_array_put_ptr,

	.map_release = perf_event_fd_array_release,

	.map_check_btf = map_check_no_btf,

};



#ifdef CONFIG_CGROUPS
@@ -665,6 +661,7 @@ const struct bpf_map_ops cgroup_array_map_ops = { 
	.map_delete_elem = fd_array_map_delete_elem,

	.map_fd_get_ptr = cgroup_fd_array_get_ptr,

	.map_fd_put_ptr = cgroup_fd_array_put_ptr,

	.map_check_btf = map_check_no_btf,

};

#endif
@@ -749,4 +746,5 @@ const struct bpf_map_ops array_of_maps_map_ops = { 
	.map_fd_put_ptr = bpf_map_fd_put_ptr,

	.map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,

	.map_gen_lookup = array_of_map_gen_lookup,

	.map_check_btf = map_check_no_btf,

};

kernel/bpf/cpumap.c

+1 −0
Original line number Diff line number Diff line
@@ -555,6 +555,7 @@ const struct bpf_map_ops cpu_map_ops = { 
	.map_update_elem	= cpu_map_update_elem,

	.map_lookup_elem	= cpu_map_lookup_elem,

	.map_get_next_key	= cpu_map_get_next_key,

	.map_check_btf		= map_check_no_btf,

};



static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu,

kernel/bpf/devmap.c

+1 −0
Original line number Diff line number Diff line
@@ -484,6 +484,7 @@ const struct bpf_map_ops dev_map_ops = { 
	.map_lookup_elem = dev_map_lookup_elem,

	.map_update_elem = dev_map_update_elem,

	.map_delete_elem = dev_map_delete_elem,

	.map_check_btf = map_check_no_btf,

};



static int dev_map_notification(struct notifier_block *notifier,

kernel/bpf/hashtab.c

+1 −19
Original line number Diff line number Diff line
@@ -1185,23 +1185,6 @@ static void htab_map_seq_show_elem(struct bpf_map *map, void *key, 
	rcu_read_unlock();

}



static int htab_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;

}



const struct bpf_map_ops htab_map_ops = {

	.map_alloc_check = htab_map_alloc_check,

	.map_alloc = htab_map_alloc,
@@ -1212,7 +1195,6 @@ const struct bpf_map_ops htab_map_ops = { 
	.map_delete_elem = htab_map_delete_elem,

	.map_gen_lookup = htab_map_gen_lookup,

	.map_seq_show_elem = htab_map_seq_show_elem,

	.map_check_btf = htab_map_check_btf,

};



const struct bpf_map_ops htab_lru_map_ops = {
@@ -1225,7 +1207,6 @@ const struct bpf_map_ops htab_lru_map_ops = { 
	.map_delete_elem = htab_lru_map_delete_elem,

	.map_gen_lookup = htab_lru_map_gen_lookup,

	.map_seq_show_elem = htab_map_seq_show_elem,

	.map_check_btf = htab_map_check_btf,

};



/* Called from eBPF program */
@@ -1452,4 +1433,5 @@ const struct bpf_map_ops htab_of_maps_map_ops = { 
	.map_fd_put_ptr = bpf_map_fd_put_ptr,

	.map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,

	.map_gen_lookup = htab_of_map_gen_lookup,

	.map_check_btf = map_check_no_btf,

};

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