Hi Wang,
On Fri, Nov 27, 2015 at 08:47:36AM +0000, Wang Nan wrote:
> 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 <wangn...@huawei.com>
> Signed-off-by: He Kuang <heku...@huawei.com>
> Cc: Alexei Starovoitov <a...@kernel.org>
> Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
> Cc: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
> Cc: Namhyung Kim <namhy...@kernel.org>
> Cc: Zefan Li <lize...@huawei.com>
> Cc: pi3or...@163.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);
It means that each map name is saved in section header string table?
> + 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);
You need to check the return value.
thanks,
Namhyung
> + pr_debug("map %zu is \"%s\"\n", map_idx,
> + obj->maps[map_idx].name);
> + }
> +}
> +
--
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