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Commit 561bbcca authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo
Browse files

tools lib bpf: Extract and collect map names from BPF object file 



This patch collects name of maps in BPF object files and saves them into
'maps' field in 'struct bpf_object'. 'bpf_object__get_map_by_name' is
introduced to retrive fd and definitions of a map through its name.

Signed-off-by: default avatarHe Kuang <hekuang@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: He Kuang <hekuang@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1448614067-197576-3-git-send-email-wangnan0@huawei.com


Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 9d759a9b

tools/lib/bpf/libbpf.c

+62 −3
Original line number Diff line number Diff line
@@ -165,6 +165,7 @@ struct bpf_program { 


struct bpf_map {

	int fd;

	char *name;

	struct bpf_map_def def;

	void *priv;

	bpf_map_clear_priv_t clear_priv;
@@ -526,12 +527,46 @@ bpf_object__init_maps(struct bpf_object *obj, void *data, 
	return 0;

}



static void

bpf_object__init_maps_name(struct bpf_object *obj, int maps_shndx)

{

	int i;

	Elf_Data *symbols = obj->efile.symbols;



	if (!symbols || maps_shndx < 0)

		return;



	for (i = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) {

		GElf_Sym sym;

		size_t map_idx;

		const char *map_name;



		if (!gelf_getsym(symbols, i, &sym))

			continue;

		if (sym.st_shndx != maps_shndx)

			continue;



		map_name = elf_strptr(obj->efile.elf,

				      obj->efile.ehdr.e_shstrndx,

				      sym.st_name);

		map_idx = sym.st_value / sizeof(struct bpf_map_def);

		if (map_idx >= obj->nr_maps) {

			pr_warning("index of map \"%s\" is buggy: %zu > %zu\n",

				   map_name, map_idx, obj->nr_maps);

			continue;

		}

		obj->maps[map_idx].name = strdup(map_name);

		pr_debug("map %zu is \"%s\"\n", map_idx,

			 obj->maps[map_idx].name);

	}

}



static int bpf_object__elf_collect(struct bpf_object *obj)

{

	Elf *elf = obj->efile.elf;

	GElf_Ehdr *ep = &obj->efile.ehdr;

	Elf_Scn *scn = NULL;

	int idx = 0, err = 0;

	int idx = 0, err = 0, maps_shndx = -1;



	/* Elf is corrupted/truncated, avoid calling elf_strptr. */

	if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) {
@@ -581,10 +616,11 @@ static int bpf_object__elf_collect(struct bpf_object *obj) 
			err = bpf_object__init_kversion(obj,

							data->d_buf,

							data->d_size);

		else if (strcmp(name, "maps") == 0)

		else if (strcmp(name, "maps") == 0) {

			err = bpf_object__init_maps(obj, data->d_buf,

						    data->d_size);

		else if (sh.sh_type == SHT_SYMTAB) {

			maps_shndx = idx;

		} else if (sh.sh_type == SHT_SYMTAB) {

			if (obj->efile.symbols) {

				pr_warning("bpf: multiple SYMTAB in %s\n",

					   obj->path);
@@ -625,6 +661,9 @@ static int bpf_object__elf_collect(struct bpf_object *obj) 
		if (err)

			goto out;

	}



	if (maps_shndx >= 0)

		bpf_object__init_maps_name(obj, maps_shndx);

out:

	return err;

}
@@ -1086,6 +1125,7 @@ void bpf_object__close(struct bpf_object *obj) 
	bpf_object__unload(obj);



	for (i = 0; i < obj->nr_maps; i++) {

		zfree(&obj->maps[i].name);

		if (obj->maps[i].clear_priv)

			obj->maps[i].clear_priv(&obj->maps[i],

						obj->maps[i].priv);
@@ -1266,6 +1306,13 @@ int bpf_map__get_def(struct bpf_map *map, struct bpf_map_def *pdef) 
	return 0;

}



const char *bpf_map__get_name(struct bpf_map *map)

{

	if (!map)

		return NULL;

	return map->name;

}



int bpf_map__set_private(struct bpf_map *map, void *priv,

			 bpf_map_clear_priv_t clear_priv)

{
@@ -1318,3 +1365,15 @@ bpf_map__next(struct bpf_map *prev, struct bpf_object *obj) 
		return NULL;

	return &obj->maps[idx];

}



struct bpf_map *

bpf_object__get_map_by_name(struct bpf_object *obj, const char *name)

{

	struct bpf_map *pos;



	bpf_map__for_each(pos, obj) {

		if (strcmp(pos->name, name) == 0)

			return pos;

	}

	return NULL;

}

tools/lib/bpf/libbpf.h

+3 −0
Original line number Diff line number Diff line
@@ -170,6 +170,8 @@ struct bpf_map_def { 
 * it is not a uapi header so no need to consider name clash.

 */

struct bpf_map;

struct bpf_map *

bpf_object__get_map_by_name(struct bpf_object *obj, const char *name);



struct bpf_map *

bpf_map__next(struct bpf_map *map, struct bpf_object *obj);
@@ -180,6 +182,7 @@ bpf_map__next(struct bpf_map *map, struct bpf_object *obj); 


int bpf_map__get_fd(struct bpf_map *map);

int bpf_map__get_def(struct bpf_map *map, struct bpf_map_def *pdef);

const char *bpf_map__get_name(struct bpf_map *map);



typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *);

int bpf_map__set_private(struct bpf_map *map, void *priv,