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libbpf: refactor map initialization
User and global data maps initialization has gotten pretty complicated and unnecessarily convoluted. This patch splits out the logic for global data map and user-defined map initialization. It also removes the restriction of pre-calculating how many maps will be initialized, instead allowing to keep adding new maps as they are discovered, which will be used later for BTF-defined map definitions. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Andrii Nakryiko
Daniel Borkmann
parent
01b29d1dc9
commit
bf82927125
@ -234,6 +234,7 @@ struct bpf_object {
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size_t nr_programs;
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struct bpf_map *maps;
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size_t nr_maps;
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size_t maps_cap;
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struct bpf_secdata sections;
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bool loaded;
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@ -763,21 +764,51 @@ int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
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return -ENOENT;
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}
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static bool bpf_object__has_maps(const struct bpf_object *obj)
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static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
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{
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return obj->efile.maps_shndx >= 0 ||
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obj->efile.data_shndx >= 0 ||
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obj->efile.rodata_shndx >= 0 ||
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obj->efile.bss_shndx >= 0;
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struct bpf_map *new_maps;
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size_t new_cap;
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int i;
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if (obj->nr_maps < obj->maps_cap)
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return &obj->maps[obj->nr_maps++];
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new_cap = max(4ul, obj->maps_cap * 3 / 2);
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new_maps = realloc(obj->maps, new_cap * sizeof(*obj->maps));
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if (!new_maps) {
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pr_warning("alloc maps for object failed\n");
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return ERR_PTR(-ENOMEM);
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}
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obj->maps_cap = new_cap;
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obj->maps = new_maps;
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/* zero out new maps */
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memset(obj->maps + obj->nr_maps, 0,
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(obj->maps_cap - obj->nr_maps) * sizeof(*obj->maps));
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/*
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* fill all fd with -1 so won't close incorrect fd (fd=0 is stdin)
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* when failure (zclose won't close negative fd)).
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*/
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for (i = obj->nr_maps; i < obj->maps_cap; i++) {
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obj->maps[i].fd = -1;
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obj->maps[i].inner_map_fd = -1;
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}
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return &obj->maps[obj->nr_maps++];
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}
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static int
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bpf_object__init_internal_map(struct bpf_object *obj, struct bpf_map *map,
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enum libbpf_map_type type, Elf_Data *data,
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void **data_buff)
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bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
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Elf_Data *data, void **data_buff)
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{
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struct bpf_map_def *def = &map->def;
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char map_name[BPF_OBJ_NAME_LEN];
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struct bpf_map_def *def;
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struct bpf_map *map;
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map = bpf_object__add_map(obj);
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if (IS_ERR(map))
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return PTR_ERR(map);
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map->libbpf_type = type;
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map->offset = ~(typeof(map->offset))0;
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@ -789,6 +820,7 @@ bpf_object__init_internal_map(struct bpf_object *obj, struct bpf_map *map,
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return -ENOMEM;
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}
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def = &map->def;
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def->type = BPF_MAP_TYPE_ARRAY;
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def->key_size = sizeof(int);
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def->value_size = data->d_size;
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@ -808,29 +840,58 @@ bpf_object__init_internal_map(struct bpf_object *obj, struct bpf_map *map,
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return 0;
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}
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static int bpf_object__init_maps(struct bpf_object *obj, int flags)
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static int bpf_object__init_global_data_maps(struct bpf_object *obj)
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{
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int err;
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if (!obj->caps.global_data)
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return 0;
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/*
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* Populate obj->maps with libbpf internal maps.
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*/
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if (obj->efile.data_shndx >= 0) {
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err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
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obj->efile.data,
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&obj->sections.data);
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if (err)
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return err;
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}
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if (obj->efile.rodata_shndx >= 0) {
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err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
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obj->efile.rodata,
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&obj->sections.rodata);
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if (err)
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return err;
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}
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if (obj->efile.bss_shndx >= 0) {
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err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
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obj->efile.bss, NULL);
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if (err)
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return err;
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}
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return 0;
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}
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static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
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{
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int i, map_idx, map_def_sz = 0, nr_syms, nr_maps = 0, nr_maps_glob = 0;
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bool strict = !(flags & MAPS_RELAX_COMPAT);
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Elf_Data *symbols = obj->efile.symbols;
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int i, map_def_sz = 0, nr_maps = 0, nr_syms;
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Elf_Data *data = NULL;
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int ret = 0;
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Elf_Scn *scn;
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if (obj->efile.maps_shndx < 0)
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return 0;
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if (!symbols)
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return -EINVAL;
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nr_syms = symbols->d_size / sizeof(GElf_Sym);
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if (obj->efile.maps_shndx >= 0) {
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Elf_Scn *scn = elf_getscn(obj->efile.elf,
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obj->efile.maps_shndx);
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if (scn)
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data = elf_getdata(scn, NULL);
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if (!scn || !data) {
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pr_warning("failed to get Elf_Data from map section %d\n",
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obj->efile.maps_shndx);
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return -EINVAL;
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}
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scn = elf_getscn(obj->efile.elf, obj->efile.maps_shndx);
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if (scn)
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data = elf_getdata(scn, NULL);
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if (!scn || !data) {
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pr_warning("failed to get Elf_Data from map section %d\n",
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obj->efile.maps_shndx);
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return -EINVAL;
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}
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/*
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@ -840,16 +901,8 @@ static int bpf_object__init_maps(struct bpf_object *obj, int flags)
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*
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* TODO: Detect array of map and report error.
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*/
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if (obj->caps.global_data) {
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if (obj->efile.data_shndx >= 0)
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nr_maps_glob++;
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if (obj->efile.rodata_shndx >= 0)
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nr_maps_glob++;
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if (obj->efile.bss_shndx >= 0)
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nr_maps_glob++;
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}
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for (i = 0; data && i < nr_syms; i++) {
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nr_syms = symbols->d_size / sizeof(GElf_Sym);
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for (i = 0; i < nr_syms; i++) {
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GElf_Sym sym;
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if (!gelf_getsym(symbols, i, &sym))
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@ -858,79 +911,56 @@ static int bpf_object__init_maps(struct bpf_object *obj, int flags)
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continue;
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nr_maps++;
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}
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if (!nr_maps && !nr_maps_glob)
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return 0;
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/* Assume equally sized map definitions */
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if (data) {
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pr_debug("maps in %s: %d maps in %zd bytes\n", obj->path,
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nr_maps, data->d_size);
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pr_debug("maps in %s: %d maps in %zd bytes\n",
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obj->path, nr_maps, data->d_size);
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map_def_sz = data->d_size / nr_maps;
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if (!data->d_size || (data->d_size % nr_maps) != 0) {
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pr_warning("unable to determine map definition size "
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"section %s, %d maps in %zd bytes\n",
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obj->path, nr_maps, data->d_size);
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return -EINVAL;
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}
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map_def_sz = data->d_size / nr_maps;
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if (!data->d_size || (data->d_size % nr_maps) != 0) {
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pr_warning("unable to determine map definition size "
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"section %s, %d maps in %zd bytes\n",
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obj->path, nr_maps, data->d_size);
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return -EINVAL;
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}
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nr_maps += nr_maps_glob;
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obj->maps = calloc(nr_maps, sizeof(obj->maps[0]));
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if (!obj->maps) {
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pr_warning("alloc maps for object failed\n");
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return -ENOMEM;
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}
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obj->nr_maps = nr_maps;
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for (i = 0; i < nr_maps; i++) {
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/*
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* fill all fd with -1 so won't close incorrect
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* fd (fd=0 is stdin) when failure (zclose won't close
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* negative fd)).
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*/
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obj->maps[i].fd = -1;
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obj->maps[i].inner_map_fd = -1;
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}
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/*
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* Fill obj->maps using data in "maps" section.
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*/
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for (i = 0, map_idx = 0; data && i < nr_syms; i++) {
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/* Fill obj->maps using data in "maps" section. */
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for (i = 0; i < nr_syms; i++) {
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GElf_Sym sym;
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const char *map_name;
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struct bpf_map_def *def;
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struct bpf_map *map;
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if (!gelf_getsym(symbols, i, &sym))
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continue;
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if (sym.st_shndx != obj->efile.maps_shndx)
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continue;
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map_name = elf_strptr(obj->efile.elf,
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obj->efile.strtabidx,
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map = bpf_object__add_map(obj);
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if (IS_ERR(map))
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return PTR_ERR(map);
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map_name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
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sym.st_name);
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if (!map_name) {
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pr_warning("failed to get map #%d name sym string for obj %s\n",
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map_idx, obj->path);
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i, obj->path);
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return -LIBBPF_ERRNO__FORMAT;
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}
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obj->maps[map_idx].libbpf_type = LIBBPF_MAP_UNSPEC;
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obj->maps[map_idx].offset = sym.st_value;
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map->libbpf_type = LIBBPF_MAP_UNSPEC;
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map->offset = sym.st_value;
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if (sym.st_value + map_def_sz > data->d_size) {
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pr_warning("corrupted maps section in %s: last map \"%s\" too small\n",
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obj->path, map_name);
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return -EINVAL;
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}
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obj->maps[map_idx].name = strdup(map_name);
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if (!obj->maps[map_idx].name) {
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map->name = strdup(map_name);
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if (!map->name) {
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pr_warning("failed to alloc map name\n");
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return -ENOMEM;
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}
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pr_debug("map %d is \"%s\"\n", map_idx,
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obj->maps[map_idx].name);
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pr_debug("map %d is \"%s\"\n", i, map->name);
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def = (struct bpf_map_def *)(data->d_buf + sym.st_value);
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/*
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* If the definition of the map in the object file fits in
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@ -939,7 +969,7 @@ static int bpf_object__init_maps(struct bpf_object *obj, int flags)
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* calloc above.
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*/
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if (map_def_sz <= sizeof(struct bpf_map_def)) {
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memcpy(&obj->maps[map_idx].def, def, map_def_sz);
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memcpy(&map->def, def, map_def_sz);
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} else {
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/*
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* Here the map structure being read is bigger than what
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@ -959,37 +989,30 @@ static int bpf_object__init_maps(struct bpf_object *obj, int flags)
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return -EINVAL;
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}
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}
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memcpy(&obj->maps[map_idx].def, def,
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sizeof(struct bpf_map_def));
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memcpy(&map->def, def, sizeof(struct bpf_map_def));
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}
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map_idx++;
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}
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return 0;
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}
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if (!obj->caps.global_data)
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goto finalize;
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static int bpf_object__init_maps(struct bpf_object *obj, int flags)
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{
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bool strict = !(flags & MAPS_RELAX_COMPAT);
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int err;
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/*
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* Populate rest of obj->maps with libbpf internal maps.
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*/
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if (obj->efile.data_shndx >= 0)
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ret = bpf_object__init_internal_map(obj, &obj->maps[map_idx++],
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LIBBPF_MAP_DATA,
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obj->efile.data,
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&obj->sections.data);
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if (!ret && obj->efile.rodata_shndx >= 0)
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ret = bpf_object__init_internal_map(obj, &obj->maps[map_idx++],
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LIBBPF_MAP_RODATA,
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obj->efile.rodata,
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&obj->sections.rodata);
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if (!ret && obj->efile.bss_shndx >= 0)
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ret = bpf_object__init_internal_map(obj, &obj->maps[map_idx++],
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LIBBPF_MAP_BSS,
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obj->efile.bss, NULL);
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finalize:
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if (!ret)
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err = bpf_object__init_user_maps(obj, strict);
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if (err)
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return err;
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err = bpf_object__init_global_data_maps(obj);
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if (err)
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return err;
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if (obj->nr_maps) {
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qsort(obj->maps, obj->nr_maps, sizeof(obj->maps[0]),
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compare_bpf_map);
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return ret;
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}
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return 0;
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}
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static bool section_have_execinstr(struct bpf_object *obj, int idx)
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@ -1262,14 +1285,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
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return -LIBBPF_ERRNO__FORMAT;
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}
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err = bpf_object__load_btf(obj, btf_data, btf_ext_data);
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if (err)
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return err;
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if (bpf_object__has_maps(obj)) {
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if (!err)
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err = bpf_object__init_maps(obj, flags);
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if (err)
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return err;
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}
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err = bpf_object__init_prog_names(obj);
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if (!err)
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err = bpf_object__init_prog_names(obj);
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return err;
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}
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