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libbpf: Refactor BTF map definition parsing 

Refactor BTF-defined maps parsing logic to allow it to be nicely reused by BPF
static linker. Further, at least for BPF static linker, it's important to know
which attributes of a BPF map were defined explicitly, so provide a bit set
for each known portion of BTF map definition. This allows BPF static linker to
do a simple check when dealing with extern map declarations.

The same capabilities allow to distinguish attributes explicitly set to zero
(e.g., __uint(max_entries, 0)) vs the case of not specifying it at all (no
max_entries attribute at all). Libbpf is currently not utilizing that, but it
could be useful for backwards compatibility reasons later.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210423181348.1801389-7-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2021-04-23 11:13:36 -07:00 committed by Alexei Starovoitov
parent 6245947c1b
commit c7ef5ec957
2 changed files with 178 additions and 111 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

257
tools/lib/bpf/libbpf.c
View File

@ -2025,255 +2025,262 @@ static int build_map_pin_path(struct bpf_map *map, const char *path)
return bpf_map__set_pin_path(map, buf);
}
static int parse_btf_map_def(struct bpf_object *obj,
struct bpf_map *map,
const struct btf_type *def,
bool strict, bool is_inner,
const char *pin_root_path)
int parse_btf_map_def(const char *map_name, struct btf *btf,
const struct btf_type *def_t, bool strict,
struct btf_map_def *map_def, struct btf_map_def *inner_def)
{
const struct btf_type *t;
const struct btf_member *m;
bool is_inner = inner_def == NULL;
int vlen, i;
vlen = btf_vlen(def);
m = btf_members(def);
vlen = btf_vlen(def_t);
m = btf_members(def_t);
for (i = 0; i < vlen; i++, m++) {
const char *name = btf__name_by_offset(obj->btf, m->name_off);
const char *name = btf__name_by_offset(btf, m->name_off);
if (!name) {
pr_warn("map '%s': invalid field #%d.\n", map->name, i);
pr_warn("map '%s': invalid field #%d.\n", map_name, i);
return -EINVAL;
}
if (strcmp(name, "type") == 0) {
if (!get_map_field_int(map->name, obj->btf, m,
&map->def.type))
if (!get_map_field_int(map_name, btf, m, &map_def->map_type))
return -EINVAL;
pr_debug("map '%s': found type = %u.\n",
map->name, map->def.type);
map_def->parts |= MAP_DEF_MAP_TYPE;
} else if (strcmp(name, "max_entries") == 0) {
if (!get_map_field_int(map->name, obj->btf, m,
&map->def.max_entries))
if (!get_map_field_int(map_name, btf, m, &map_def->max_entries))
return -EINVAL;
pr_debug("map '%s': found max_entries = %u.\n",
map->name, map->def.max_entries);
map_def->parts |= MAP_DEF_MAX_ENTRIES;
} else if (strcmp(name, "map_flags") == 0) {
if (!get_map_field_int(map->name, obj->btf, m,
&map->def.map_flags))
if (!get_map_field_int(map_name, btf, m, &map_def->map_flags))
return -EINVAL;
pr_debug("map '%s': found map_flags = %u.\n",
map->name, map->def.map_flags);
map_def->parts |= MAP_DEF_MAP_FLAGS;
} else if (strcmp(name, "numa_node") == 0) {
if (!get_map_field_int(map->name, obj->btf, m, &map->numa_node))
if (!get_map_field_int(map_name, btf, m, &map_def->numa_node))
return -EINVAL;
pr_debug("map '%s': found numa_node = %u.\n", map->name, map->numa_node);
map_def->parts |= MAP_DEF_NUMA_NODE;
} else if (strcmp(name, "key_size") == 0) {
__u32 sz;
if (!get_map_field_int(map->name, obj->btf, m, &sz))
if (!get_map_field_int(map_name, btf, m, &sz))
return -EINVAL;
pr_debug("map '%s': found key_size = %u.\n",
map->name, sz);
if (map->def.key_size && map->def.key_size != sz) {
if (map_def->key_size && map_def->key_size != sz) {
pr_warn("map '%s': conflicting key size %u != %u.\n",
map->name, map->def.key_size, sz);
map_name, map_def->key_size, sz);
return -EINVAL;
}
map->def.key_size = sz;
map_def->key_size = sz;
map_def->parts |= MAP_DEF_KEY_SIZE;
} else if (strcmp(name, "key") == 0) {
__s64 sz;
t = btf__type_by_id(obj->btf, m->type);
t = btf__type_by_id(btf, m->type);
if (!t) {
pr_warn("map '%s': key type [%d] not found.\n",
map->name, m->type);
map_name, m->type);
return -EINVAL;
}
if (!btf_is_ptr(t)) {
pr_warn("map '%s': key spec is not PTR: %s.\n",
map->name, btf_kind_str(t));
map_name, btf_kind_str(t));
return -EINVAL;
}
sz = btf__resolve_size(obj->btf, t->type);
sz = btf__resolve_size(btf, t->type);
if (sz < 0) {
pr_warn("map '%s': can't determine key size for type [%u]: %zd.\n",
map->name, t->type, (ssize_t)sz);
map_name, t->type, (ssize_t)sz);
return sz;
}
pr_debug("map '%s': found key [%u], sz = %zd.\n",
map->name, t->type, (ssize_t)sz);
if (map->def.key_size && map->def.key_size != sz) {
if (map_def->key_size && map_def->key_size != sz) {
pr_warn("map '%s': conflicting key size %u != %zd.\n",
map->name, map->def.key_size, (ssize_t)sz);
map_name, map_def->key_size, (ssize_t)sz);
return -EINVAL;
}
map->def.key_size = sz;
map->btf_key_type_id = t->type;
map_def->key_size = sz;
map_def->key_type_id = t->type;
map_def->parts |= MAP_DEF_KEY_SIZE | MAP_DEF_KEY_TYPE;
} else if (strcmp(name, "value_size") == 0) {
__u32 sz;
if (!get_map_field_int(map->name, obj->btf, m, &sz))
if (!get_map_field_int(map_name, btf, m, &sz))
return -EINVAL;
pr_debug("map '%s': found value_size = %u.\n",
map->name, sz);
if (map->def.value_size && map->def.value_size != sz) {
if (map_def->value_size && map_def->value_size != sz) {
pr_warn("map '%s': conflicting value size %u != %u.\n",
map->name, map->def.value_size, sz);
map_name, map_def->value_size, sz);
return -EINVAL;
}
map->def.value_size = sz;
map_def->value_size = sz;
map_def->parts |= MAP_DEF_VALUE_SIZE;
} else if (strcmp(name, "value") == 0) {
__s64 sz;
t = btf__type_by_id(obj->btf, m->type);
t = btf__type_by_id(btf, m->type);
if (!t) {
pr_warn("map '%s': value type [%d] not found.\n",
map->name, m->type);
map_name, m->type);
return -EINVAL;
}
if (!btf_is_ptr(t)) {
pr_warn("map '%s': value spec is not PTR: %s.\n",
map->name, btf_kind_str(t));
map_name, btf_kind_str(t));
return -EINVAL;
}
sz = btf__resolve_size(obj->btf, t->type);
sz = btf__resolve_size(btf, t->type);
if (sz < 0) {
pr_warn("map '%s': can't determine value size for type [%u]: %zd.\n",
map->name, t->type, (ssize_t)sz);
map_name, t->type, (ssize_t)sz);
return sz;
}
pr_debug("map '%s': found value [%u], sz = %zd.\n",
map->name, t->type, (ssize_t)sz);
if (map->def.value_size && map->def.value_size != sz) {
if (map_def->value_size && map_def->value_size != sz) {
pr_warn("map '%s': conflicting value size %u != %zd.\n",
map->name, map->def.value_size, (ssize_t)sz);
map_name, map_def->value_size, (ssize_t)sz);
return -EINVAL;
}
map->def.value_size = sz;
map->btf_value_type_id = t->type;
map_def->value_size = sz;
map_def->value_type_id = t->type;
map_def->parts |= MAP_DEF_VALUE_SIZE | MAP_DEF_VALUE_TYPE;
}
else if (strcmp(name, "values") == 0) {
char inner_map_name[128];
int err;
if (is_inner) {
pr_warn("map '%s': multi-level inner maps not supported.\n",
map->name);
map_name);
return -ENOTSUP;
}
if (i != vlen - 1) {
pr_warn("map '%s': '%s' member should be last.\n",
map->name, name);
map_name, name);
return -EINVAL;
}
if (!bpf_map_type__is_map_in_map(map->def.type)) {
if (!bpf_map_type__is_map_in_map(map_def->map_type)) {
pr_warn("map '%s': should be map-in-map.\n",
map->name);
map_name);
return -ENOTSUP;
}
if (map->def.value_size && map->def.value_size != 4) {
if (map_def->value_size && map_def->value_size != 4) {
pr_warn("map '%s': conflicting value size %u != 4.\n",
map->name, map->def.value_size);
map_name, map_def->value_size);
return -EINVAL;
}
map->def.value_size = 4;
t = btf__type_by_id(obj->btf, m->type);
map_def->value_size = 4;
t = btf__type_by_id(btf, m->type);
if (!t) {
pr_warn("map '%s': map-in-map inner type [%d] not found.\n",
map->name, m->type);
map_name, m->type);
return -EINVAL;
}
if (!btf_is_array(t) || btf_array(t)->nelems) {
pr_warn("map '%s': map-in-map inner spec is not a zero-sized array.\n",
map->name);
map_name);
return -EINVAL;
}
t = skip_mods_and_typedefs(obj->btf, btf_array(t)->type,
NULL);
t = skip_mods_and_typedefs(btf, btf_array(t)->type, NULL);
if (!btf_is_ptr(t)) {
pr_warn("map '%s': map-in-map inner def is of unexpected kind %s.\n",
map->name, btf_kind_str(t));
map_name, btf_kind_str(t));
return -EINVAL;
}
t = skip_mods_and_typedefs(obj->btf, t->type, NULL);
t = skip_mods_and_typedefs(btf, t->type, NULL);
if (!btf_is_struct(t)) {
pr_warn("map '%s': map-in-map inner def is of unexpected kind %s.\n",
map->name, btf_kind_str(t));
map_name, btf_kind_str(t));
return -EINVAL;
}
map->inner_map = calloc(1, sizeof(*map->inner_map));
if (!map->inner_map)
return -ENOMEM;
map->inner_map->fd = -1;
map->inner_map->sec_idx = obj->efile.btf_maps_shndx;
map->inner_map->name = malloc(strlen(map->name) +
sizeof(".inner") + 1);
if (!map->inner_map->name)
return -ENOMEM;
sprintf(map->inner_map->name, "%s.inner", map->name);
err = parse_btf_map_def(obj, map->inner_map, t, strict,
true /* is_inner */, NULL);
snprintf(inner_map_name, sizeof(inner_map_name), "%s.inner", map_name);
err = parse_btf_map_def(inner_map_name, btf, t, strict, inner_def, NULL);
if (err)
return err;
map_def->parts |= MAP_DEF_INNER_MAP;
} else if (strcmp(name, "pinning") == 0) {
__u32 val;
int err;
if (is_inner) {
pr_debug("map '%s': inner def can't be pinned.\n",
map->name);
pr_warn("map '%s': inner def can't be pinned.\n", map_name);
return -EINVAL;
}
if (!get_map_field_int(map->name, obj->btf, m, &val))
if (!get_map_field_int(map_name, btf, m, &val))
return -EINVAL;
pr_debug("map '%s': found pinning = %u.\n",
map->name, val);
if (val != LIBBPF_PIN_NONE &&
val != LIBBPF_PIN_BY_NAME) {
if (val != LIBBPF_PIN_NONE && val != LIBBPF_PIN_BY_NAME) {
pr_warn("map '%s': invalid pinning value %u.\n",
map->name, val);
map_name, val);
return -EINVAL;
}
if (val == LIBBPF_PIN_BY_NAME) {
err = build_map_pin_path(map, pin_root_path);
if (err) {
pr_warn("map '%s': couldn't build pin path.\n",
map->name);
return err;
}
}
map_def->pinning = val;
map_def->parts |= MAP_DEF_PINNING;
} else {
if (strict) {
pr_warn("map '%s': unknown field '%s'.\n",
map->name, name);
pr_warn("map '%s': unknown field '%s'.\n", map_name, name);
return -ENOTSUP;
}
pr_debug("map '%s': ignoring unknown field '%s'.\n",
map->name, name);
pr_debug("map '%s': ignoring unknown field '%s'.\n", map_name, name);
}
}
if (map->def.type == BPF_MAP_TYPE_UNSPEC) {
pr_warn("map '%s': map type isn't specified.\n", map->name);
if (map_def->map_type == BPF_MAP_TYPE_UNSPEC) {
pr_warn("map '%s': map type isn't specified.\n", map_name);
return -EINVAL;
}
return 0;
}
static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def)
{
map->def.type = def->map_type;
map->def.key_size = def->key_size;
map->def.value_size = def->value_size;
map->def.max_entries = def->max_entries;
map->def.map_flags = def->map_flags;
map->numa_node = def->numa_node;
map->btf_key_type_id = def->key_type_id;
map->btf_value_type_id = def->value_type_id;
if (def->parts & MAP_DEF_MAP_TYPE)
pr_debug("map '%s': found type = %u.\n", map->name, def->map_type);
if (def->parts & MAP_DEF_KEY_TYPE)
pr_debug("map '%s': found key [%u], sz = %u.\n",
map->name, def->key_type_id, def->key_size);
else if (def->parts & MAP_DEF_KEY_SIZE)
pr_debug("map '%s': found key_size = %u.\n", map->name, def->key_size);
if (def->parts & MAP_DEF_VALUE_TYPE)
pr_debug("map '%s': found value [%u], sz = %u.\n",
map->name, def->value_type_id, def->value_size);
else if (def->parts & MAP_DEF_VALUE_SIZE)
pr_debug("map '%s': found value_size = %u.\n", map->name, def->value_size);
if (def->parts & MAP_DEF_MAX_ENTRIES)
pr_debug("map '%s': found max_entries = %u.\n", map->name, def->max_entries);
if (def->parts & MAP_DEF_MAP_FLAGS)
pr_debug("map '%s': found map_flags = %u.\n", map->name, def->map_flags);
if (def->parts & MAP_DEF_PINNING)
pr_debug("map '%s': found pinning = %u.\n", map->name, def->pinning);
if (def->parts & MAP_DEF_NUMA_NODE)
pr_debug("map '%s': found numa_node = %u.\n", map->name, def->numa_node);
if (def->parts & MAP_DEF_INNER_MAP)
pr_debug("map '%s': found inner map definition.\n", map->name);
}
static int bpf_object__init_user_btf_map(struct bpf_object *obj,
const struct btf_type *sec,
int var_idx, int sec_idx,
const Elf_Data *data, bool strict,
const char *pin_root_path)
{
struct btf_map_def map_def = {}, inner_def = {};
const struct btf_type *var, *def;
const struct btf_var_secinfo *vi;
const struct btf_var *var_extra;
const char *map_name;
struct bpf_map *map;
int err;
vi = btf_var_secinfos(sec) + var_idx;
var = btf__type_by_id(obj->btf, vi->type);
@ -2327,7 +2334,35 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
map_name, map->sec_idx, map->sec_offset);
return parse_btf_map_def(obj, map, def, strict, false, pin_root_path);
err = parse_btf_map_def(map->name, obj->btf, def, strict, &map_def, &inner_def);
if (err)
return err;
fill_map_from_def(map, &map_def);
if (map_def.pinning == LIBBPF_PIN_BY_NAME) {
err = build_map_pin_path(map, pin_root_path);
if (err) {
pr_warn("map '%s': couldn't build pin path.\n", map->name);
return err;
}
}
if (map_def.parts & MAP_DEF_INNER_MAP) {
map->inner_map = calloc(1, sizeof(*map->inner_map));
if (!map->inner_map)
return -ENOMEM;
map->inner_map->fd = -1;
map->inner_map->sec_idx = sec_idx;
map->inner_map->name = malloc(strlen(map_name) + sizeof(".inner") + 1);
if (!map->inner_map->name)
return -ENOMEM;
sprintf(map->inner_map->name, "%s.inner", map_name);
fill_map_from_def(map->inner_map, &inner_def);
}
return 0;
}
static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,

32
tools/lib/bpf/libbpf_internal.h
View File

@ -138,6 +138,38 @@ static inline __u32 btf_type_info(int kind, int vlen, int kflag)
return (kflag << 31) | (kind << 24) | vlen;
}
enum map_def_parts {
MAP_DEF_MAP_TYPE = 0x001,
MAP_DEF_KEY_TYPE = 0x002,
MAP_DEF_KEY_SIZE = 0x004,
MAP_DEF_VALUE_TYPE = 0x008,
MAP_DEF_VALUE_SIZE = 0x010,
MAP_DEF_MAX_ENTRIES = 0x020,
MAP_DEF_MAP_FLAGS = 0x040,
MAP_DEF_NUMA_NODE = 0x080,
MAP_DEF_PINNING = 0x100,
MAP_DEF_INNER_MAP = 0x200,
MAP_DEF_ALL = 0x3ff, /* combination of all above */
};
struct btf_map_def {
enum map_def_parts parts;
__u32 map_type;
__u32 key_type_id;
__u32 key_size;
__u32 value_type_id;
__u32 value_size;
__u32 max_entries;
__u32 map_flags;
__u32 numa_node;
__u32 pinning;
};
int parse_btf_map_def(const char *map_name, struct btf *btf,
const struct btf_type *def_t, bool strict,
struct btf_map_def *map_def, struct btf_map_def *inner_def);
void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
size_t cur_cnt, size_t max_cnt, size_t add_cnt);
int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt);