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Message-ID: <1448614067-197576-3-git-send-email-wangnan0@huawei.com>
Date: Fri, 27 Nov 2015 08:47:36 +0000
From: Wang Nan <wangnan0@...wei.com>
To: <acme@...nel.org>, <ast@...nel.org>
CC: <linux-kernel@...r.kernel.org>, <masami.hiramatsu.pt@...achi.com>,
<namhyung@...nel.org>, <lizefan@...wei.com>, <pi3orama@....com>,
Wang Nan <wangnan0@...wei.com>, He Kuang <hekuang@...wei.com>,
"Arnaldo Carvalho de Melo" <acme@...hat.com>
Subject: [PATCH v2 02/13] bpf tools: 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: Wang Nan <wangnan0@...wei.com>
Signed-off-by: He Kuang <hekuang@...wei.com>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Zefan Li <lizefan@...wei.com>
Cc: pi3orama@....com
---
tools/lib/bpf/libbpf.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++---
tools/lib/bpf/libbpf.h | 3 +++
2 files changed, 65 insertions(+), 3 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index f509825..a298614 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -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;
+}
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index ef63125..a51594c 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -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,
--
1.8.3.4
--
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