Commit 430025e5 authored by Delyan Kratunov's avatar Delyan Kratunov Committed by Andrii Nakryiko
Browse files

libbpf: Add subskeleton scaffolding 



In symmetry with bpf_object__open_skeleton(),
bpf_object__open_subskeleton() performs the actual walking and linking
of maps, progs, and globals described by bpf_*_skeleton objects.

Signed-off-by: default avatarDelyan Kratunov <delyank@fb.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/6942a46fbe20e7ebf970affcca307ba616985b15.1647473511.git.delyank@fb.com
parent 262cfb74

tools/lib/bpf/libbpf.c

+118 −21
Original line number Diff line number Diff line
@@ -11989,6 +11989,49 @@ int libbpf_num_possible_cpus(void) 
	return tmp_cpus;

}



static int populate_skeleton_maps(const struct bpf_object *obj,

				  struct bpf_map_skeleton *maps,

				  size_t map_cnt)

{

	int i;



	for (i = 0; i < map_cnt; i++) {

		struct bpf_map **map = maps[i].map;

		const char *name = maps[i].name;

		void **mmaped = maps[i].mmaped;



		*map = bpf_object__find_map_by_name(obj, name);

		if (!*map) {

			pr_warn("failed to find skeleton map '%s'\n", name);

			return -ESRCH;

		}



		/* externs shouldn't be pre-setup from user code */

		if (mmaped && (*map)->libbpf_type != LIBBPF_MAP_KCONFIG)

			*mmaped = (*map)->mmaped;

	}

	return 0;

}



static int populate_skeleton_progs(const struct bpf_object *obj,

				   struct bpf_prog_skeleton *progs,

				   size_t prog_cnt)

{

	int i;



	for (i = 0; i < prog_cnt; i++) {

		struct bpf_program **prog = progs[i].prog;

		const char *name = progs[i].name;



		*prog = bpf_object__find_program_by_name(obj, name);

		if (!*prog) {

			pr_warn("failed to find skeleton program '%s'\n", name);

			return -ESRCH;

		}

	}

	return 0;

}



int bpf_object__open_skeleton(struct bpf_object_skeleton *s,

			      const struct bpf_object_open_opts *opts)

{
@@ -11996,7 +12039,7 @@ int bpf_object__open_skeleton(struct bpf_object_skeleton *s, 
		.object_name = s->name,

	);

	struct bpf_object *obj;

	int i, err;

	int err;



	/* Attempt to preserve opts->object_name, unless overriden by user

	 * explicitly. Overwriting object name for skeletons is discouraged,
@@ -12019,37 +12062,91 @@ int bpf_object__open_skeleton(struct bpf_object_skeleton *s, 
	}



	*s->obj = obj;

	err = populate_skeleton_maps(obj, s->maps, s->map_cnt);

	if (err) {

		pr_warn("failed to populate skeleton maps for '%s': %d\n", s->name, err);

		return libbpf_err(err);

	}



	for (i = 0; i < s->map_cnt; i++) {

		struct bpf_map **map = s->maps[i].map;

		const char *name = s->maps[i].name;

		void **mmaped = s->maps[i].mmaped;

	err = populate_skeleton_progs(obj, s->progs, s->prog_cnt);

	if (err) {

		pr_warn("failed to populate skeleton progs for '%s': %d\n", s->name, err);

		return libbpf_err(err);

	}



		*map = bpf_object__find_map_by_name(obj, name);

		if (!*map) {

			pr_warn("failed to find skeleton map '%s'\n", name);

			return libbpf_err(-ESRCH);

	return 0;

}



		/* externs shouldn't be pre-setup from user code */

		if (mmaped && (*map)->libbpf_type != LIBBPF_MAP_KCONFIG)

			*mmaped = (*map)->mmaped;

int bpf_object__open_subskeleton(struct bpf_object_subskeleton *s)

{

	int err, len, var_idx, i;

	const char *var_name;

	const struct bpf_map *map;

	struct btf *btf;

	__u32 map_type_id;

	const struct btf_type *map_type, *var_type;

	const struct bpf_var_skeleton *var_skel;

	struct btf_var_secinfo *var;



	if (!s->obj)

		return libbpf_err(-EINVAL);



	btf = bpf_object__btf(s->obj);

	if (!btf) {

		pr_warn("subskeletons require BTF at runtime (object %s)\n",

		        bpf_object__name(s->obj));

		return libbpf_err(-errno);

	}



	for (i = 0; i < s->prog_cnt; i++) {

		struct bpf_program **prog = s->progs[i].prog;

		const char *name = s->progs[i].name;

	err = populate_skeleton_maps(s->obj, s->maps, s->map_cnt);

	if (err) {

		pr_warn("failed to populate subskeleton maps: %d\n", err);

		return libbpf_err(err);

	}



		*prog = bpf_object__find_program_by_name(obj, name);

		if (!*prog) {

			pr_warn("failed to find skeleton program '%s'\n", name);

			return libbpf_err(-ESRCH);

	err = populate_skeleton_progs(s->obj, s->progs, s->prog_cnt);

	if (err) {

		pr_warn("failed to populate subskeleton maps: %d\n", err);

		return libbpf_err(err);

	}



	for (var_idx = 0; var_idx < s->var_cnt; var_idx++) {

		var_skel = &s->vars[var_idx];

		map = *var_skel->map;

		map_type_id = bpf_map__btf_value_type_id(map);

		map_type = btf__type_by_id(btf, map_type_id);



		if (!btf_is_datasec(map_type)) {

			pr_warn("type for map '%1$s' is not a datasec: %2$s",

				bpf_map__name(map),

				__btf_kind_str(btf_kind(map_type)));

			return libbpf_err(-EINVAL);

		}



		len = btf_vlen(map_type);

		var = btf_var_secinfos(map_type);

		for (i = 0; i < len; i++, var++) {

			var_type = btf__type_by_id(btf, var->type);

			var_name = btf__name_by_offset(btf, var_type->name_off);

			if (strcmp(var_name, var_skel->name) == 0) {

				*var_skel->addr = map->mmaped + var->offset;

				break;

			}

		}

	}

	return 0;

}



void bpf_object__destroy_subskeleton(struct bpf_object_subskeleton *s)

{

	if (!s)

		return;

	free(s->maps);

	free(s->progs);

	free(s->vars);

	free(s);

}



int bpf_object__load_skeleton(struct bpf_object_skeleton *s)

{

	int i, err;

tools/lib/bpf/libbpf.h

+29 −0
Original line number Diff line number Diff line
@@ -1312,6 +1312,35 @@ LIBBPF_API int bpf_object__attach_skeleton(struct bpf_object_skeleton *s); 
LIBBPF_API void bpf_object__detach_skeleton(struct bpf_object_skeleton *s);

LIBBPF_API void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s);



struct bpf_var_skeleton {

	const char *name;

	struct bpf_map **map;

	void **addr;

};



struct bpf_object_subskeleton {

	size_t sz; /* size of this struct, for forward/backward compatibility */



	const struct bpf_object *obj;



	int map_cnt;

	int map_skel_sz; /* sizeof(struct bpf_map_skeleton) */

	struct bpf_map_skeleton *maps;



	int prog_cnt;

	int prog_skel_sz; /* sizeof(struct bpf_prog_skeleton) */

	struct bpf_prog_skeleton *progs;



	int var_cnt;

	int var_skel_sz; /* sizeof(struct bpf_var_skeleton) */

	struct bpf_var_skeleton *vars;

};



LIBBPF_API int

bpf_object__open_subskeleton(struct bpf_object_subskeleton *s);

LIBBPF_API void

bpf_object__destroy_subskeleton(struct bpf_object_subskeleton *s);



struct gen_loader_opts {

	size_t sz; /* size of this struct, for forward/backward compatiblity */

	const char *data;

tools/lib/bpf/libbpf.map

+2 −0
Original line number Diff line number Diff line
@@ -442,6 +442,8 @@ LIBBPF_0.7.0 { 


LIBBPF_0.8.0 {

	global:

		bpf_object__destroy_subskeleton;

		bpf_object__open_subskeleton;

		libbpf_register_prog_handler;

		libbpf_unregister_prog_handler;

		bpf_program__attach_kprobe_multi_opts;