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

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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: He 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: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Wang Nan 2015-11-27 08:47:36 +00:00 committed by Arnaldo Carvalho de Melo
parent 9d759a9b4a
commit 561bbccac7
2 changed files with 65 additions and 3 deletions
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65
tools/lib/bpf/libbpf.c
View file

@ -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;
}

3
tools/lib/bpf/libbpf.h
View file

@ -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,