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    Subject[tip:perf/core] tools lib bpf: Collect map definition in bpf_object
    Commit-ID:  9d759a9b4ac2690077d8b21258e6e95c3e34bfa9
    Gitweb: http://git.kernel.org/tip/9d759a9b4ac2690077d8b21258e6e95c3e34bfa9
    Author: Wang Nan <wangnan0@huawei.com>
    AuthorDate: Fri, 27 Nov 2015 08:47:35 +0000
    Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
    CommitDate: Fri, 27 Nov 2015 21:57:09 -0300

    tools lib bpf: Collect map definition in bpf_object

    This patch collects more information from maps sections in BPF object
    files into 'struct bpf_object', enables later patches access those
    information (such as the type and size of the map).

    In this patch, a new handler 'struct bpf_map' is extracted in parallel
    with bpf_object and bpf_program. Its iterator and accessor is also
    created.

    Signed-off-by: Wang Nan <wangnan0@huawei.com>
    Cc: Alexei Starovoitov <ast@kernel.org>
    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/1448614067-197576-2-git-send-email-wangnan0@huawei.com
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    tools/lib/bpf/libbpf.c | 187 +++++++++++++++++++++++++++++++++----------------
    tools/lib/bpf/libbpf.h | 21 ++++++
    2 files changed, 148 insertions(+), 60 deletions(-)

    diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
    index e3f4c33..f509825 100644
    --- a/tools/lib/bpf/libbpf.c
    +++ b/tools/lib/bpf/libbpf.c
    @@ -163,22 +163,24 @@ struct bpf_program {
    bpf_program_clear_priv_t clear_priv;
    };

    +struct bpf_map {
    + int fd;
    + struct bpf_map_def def;
    + void *priv;
    + bpf_map_clear_priv_t clear_priv;
    +};
    +
    static LIST_HEAD(bpf_objects_list);

    struct bpf_object {
    char license[64];
    u32 kern_version;
    - void *maps_buf;
    - size_t maps_buf_sz;

    struct bpf_program *programs;
    size_t nr_programs;
    - int *map_fds;
    - /*
    - * This field is required because maps_buf will be freed and
    - * maps_buf_sz will be set to 0 after loaded.
    - */
    - size_t nr_map_fds;
    + struct bpf_map *maps;
    + size_t nr_maps;
    +
    bool loaded;

    /*
    @@ -489,21 +491,38 @@ static int
    bpf_object__init_maps(struct bpf_object *obj, void *data,
    size_t size)
    {
    - if (size == 0) {
    + size_t nr_maps;
    + int i;
    +
    + nr_maps = size / sizeof(struct bpf_map_def);
    + if (!data || !nr_maps) {
    pr_debug("%s doesn't need map definition\n",
    obj->path);
    return 0;
    }

    - obj->maps_buf = malloc(size);
    - if (!obj->maps_buf) {
    - pr_warning("malloc maps failed: %s\n", obj->path);
    + pr_debug("maps in %s: %zd bytes\n", obj->path, size);
    +
    + obj->maps = calloc(nr_maps, sizeof(obj->maps[0]));
    + if (!obj->maps) {
    + pr_warning("alloc maps for object failed\n");
    return -ENOMEM;
    }
    + obj->nr_maps = nr_maps;
    +
    + for (i = 0; i < nr_maps; i++) {
    + struct bpf_map_def *def = &obj->maps[i].def;

    - obj->maps_buf_sz = size;
    - memcpy(obj->maps_buf, data, size);
    - pr_debug("maps in %s: %ld bytes\n", obj->path, (long)size);
    + /*
    + * fill all fd with -1 so won't close incorrect
    + * fd (fd=0 is stdin) when failure (zclose won't close
    + * negative fd)).
    + */
    + obj->maps[i].fd = -1;
    +
    + /* Save map definition into obj->maps */
    + *def = ((struct bpf_map_def *)data)[i];
    + }
    return 0;
    }

    @@ -688,37 +707,15 @@ static int
    bpf_object__create_maps(struct bpf_object *obj)
    {
    unsigned int i;
    - size_t nr_maps;
    - int *pfd;
    -
    - nr_maps = obj->maps_buf_sz / sizeof(struct bpf_map_def);
    - if (!obj->maps_buf || !nr_maps) {
    - pr_debug("don't need create maps for %s\n",
    - obj->path);
    - return 0;
    - }

    - obj->map_fds = malloc(sizeof(int) * nr_maps);
    - if (!obj->map_fds) {
    - pr_warning("realloc perf_bpf_map_fds failed\n");
    - return -ENOMEM;
    - }
    - obj->nr_map_fds = nr_maps;
    -
    - /* fill all fd with -1 */
    - memset(obj->map_fds, -1, sizeof(int) * nr_maps);
    + for (i = 0; i < obj->nr_maps; i++) {
    + struct bpf_map_def *def = &obj->maps[i].def;
    + int *pfd = &obj->maps[i].fd;

    - pfd = obj->map_fds;
    - for (i = 0; i < nr_maps; i++) {
    - struct bpf_map_def def;
    -
    - def = *(struct bpf_map_def *)(obj->maps_buf +
    - i * sizeof(struct bpf_map_def));
    -
    - *pfd = bpf_create_map(def.type,
    - def.key_size,
    - def.value_size,
    - def.max_entries);
    + *pfd = bpf_create_map(def->type,
    + def->key_size,
    + def->value_size,
    + def->max_entries);
    if (*pfd < 0) {
    size_t j;
    int err = *pfd;
    @@ -726,22 +723,17 @@ bpf_object__create_maps(struct bpf_object *obj)
    pr_warning("failed to create map: %s\n",
    strerror(errno));
    for (j = 0; j < i; j++)
    - zclose(obj->map_fds[j]);
    - obj->nr_map_fds = 0;
    - zfree(&obj->map_fds);
    + zclose(obj->maps[j].fd);
    return err;
    }
    pr_debug("create map: fd=%d\n", *pfd);
    - pfd++;
    }

    - zfree(&obj->maps_buf);
    - obj->maps_buf_sz = 0;
    return 0;
    }

    static int
    -bpf_program__relocate(struct bpf_program *prog, int *map_fds)
    +bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
    {
    int i;

    @@ -761,7 +753,7 @@ bpf_program__relocate(struct bpf_program *prog, int *map_fds)
    return -LIBBPF_ERRNO__RELOC;
    }
    insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
    - insns[insn_idx].imm = map_fds[map_idx];
    + insns[insn_idx].imm = obj->maps[map_idx].fd;
    }

    zfree(&prog->reloc_desc);
    @@ -780,7 +772,7 @@ bpf_object__relocate(struct bpf_object *obj)
    for (i = 0; i < obj->nr_programs; i++) {
    prog = &obj->programs[i];

    - err = bpf_program__relocate(prog, obj->map_fds);
    + err = bpf_program__relocate(prog, obj);
    if (err) {
    pr_warning("failed to relocate '%s'\n",
    prog->section_name);
    @@ -804,8 +796,7 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
    Elf_Data *data = obj->efile.reloc[i].data;
    int idx = shdr->sh_info;
    struct bpf_program *prog;
    - size_t nr_maps = obj->maps_buf_sz /
    - sizeof(struct bpf_map_def);
    + size_t nr_maps = obj->nr_maps;

    if (shdr->sh_type != SHT_REL) {
    pr_warning("internal error at %d\n", __LINE__);
    @@ -1050,10 +1041,8 @@ int bpf_object__unload(struct bpf_object *obj)
    if (!obj)
    return -EINVAL;

    - for (i = 0; i < obj->nr_map_fds; i++)
    - zclose(obj->map_fds[i]);
    - zfree(&obj->map_fds);
    - obj->nr_map_fds = 0;
    + for (i = 0; i < obj->nr_maps; i++)
    + zclose(obj->maps[i].fd);

    for (i = 0; i < obj->nr_programs; i++)
    bpf_program__unload(&obj->programs[i]);
    @@ -1096,7 +1085,15 @@ void bpf_object__close(struct bpf_object *obj)
    bpf_object__elf_finish(obj);
    bpf_object__unload(obj);

    - zfree(&obj->maps_buf);
    + for (i = 0; i < obj->nr_maps; i++) {
    + if (obj->maps[i].clear_priv)
    + obj->maps[i].clear_priv(&obj->maps[i],
    + obj->maps[i].priv);
    + obj->maps[i].priv = NULL;
    + obj->maps[i].clear_priv = NULL;
    + }
    + zfree(&obj->maps);
    + obj->nr_maps = 0;

    if (obj->programs && obj->nr_programs) {
    for (i = 0; i < obj->nr_programs; i++)
    @@ -1251,3 +1248,73 @@ int bpf_program__nth_fd(struct bpf_program *prog, int n)

    return fd;
    }
    +
    +int bpf_map__get_fd(struct bpf_map *map)
    +{
    + if (!map)
    + return -EINVAL;
    +
    + return map->fd;
    +}
    +
    +int bpf_map__get_def(struct bpf_map *map, struct bpf_map_def *pdef)
    +{
    + if (!map || !pdef)
    + return -EINVAL;
    +
    + *pdef = map->def;
    + return 0;
    +}
    +
    +int bpf_map__set_private(struct bpf_map *map, void *priv,
    + bpf_map_clear_priv_t clear_priv)
    +{
    + if (!map)
    + return -EINVAL;
    +
    + if (map->priv) {
    + if (map->clear_priv)
    + map->clear_priv(map, map->priv);
    + }
    +
    + map->priv = priv;
    + map->clear_priv = clear_priv;
    + return 0;
    +}
    +
    +int bpf_map__get_private(struct bpf_map *map, void **ppriv)
    +{
    + if (!map)
    + return -EINVAL;
    +
    + if (ppriv)
    + *ppriv = map->priv;
    + return 0;
    +}
    +
    +struct bpf_map *
    +bpf_map__next(struct bpf_map *prev, struct bpf_object *obj)
    +{
    + size_t idx;
    + struct bpf_map *s, *e;
    +
    + if (!obj || !obj->maps)
    + return NULL;
    +
    + s = obj->maps;
    + e = obj->maps + obj->nr_maps;
    +
    + if (prev == NULL)
    + return s;
    +
    + if ((prev < s) || (prev >= e)) {
    + pr_warning("error in %s: map handler doesn't belong to object\n",
    + __func__);
    + return NULL;
    + }
    +
    + idx = (prev - obj->maps) + 1;
    + if (idx >= obj->nr_maps)
    + return NULL;
    + return &obj->maps[idx];
    +}
    diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
    index 949df4b..ef63125 100644
    --- a/tools/lib/bpf/libbpf.h
    +++ b/tools/lib/bpf/libbpf.h
    @@ -165,4 +165,25 @@ struct bpf_map_def {
    unsigned int max_entries;
    };

    +/*
    + * There is another 'struct bpf_map' in include/linux/map.h. However,
    + * it is not a uapi header so no need to consider name clash.
    + */
    +struct bpf_map;
    +
    +struct bpf_map *
    +bpf_map__next(struct bpf_map *map, struct bpf_object *obj);
    +#define bpf_map__for_each(pos, obj) \
    + for ((pos) = bpf_map__next(NULL, (obj)); \
    + (pos) != NULL; \
    + (pos) = bpf_map__next((pos), (obj)))
    +
    +int bpf_map__get_fd(struct bpf_map *map);
    +int bpf_map__get_def(struct bpf_map *map, struct bpf_map_def *pdef);
    +
    +typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *);
    +int bpf_map__set_private(struct bpf_map *map, void *priv,
    + bpf_map_clear_priv_t clear_priv);
    +int bpf_map__get_private(struct bpf_map *map, void **ppriv);
    +
    #endif

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