On 4/16/21 1:23 PM, Andrii Nakryiko wrote:
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@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 256 ++++++++++++++++++--------------
tools/lib/bpf/libbpf_internal.h | 32 ++++
2 files changed, 177 insertions(+), 111 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index a0e6d6bc47f3..f6f4126389ac 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -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);
[...]
}
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;
The refactoring didn't set map->inner_map->sec_idx. I guess since
inner_map is only used internally by libbpf, so it does not
have a user visible sec_idx and hence useless? It is worthwhile to
mention in the commit message for this difference, I think.
- 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)
+{
[...]
+}
+
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 +2334,34 @@ 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;
missing set map->inner_map->sec_idx here.
+ 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,
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 92b7eae10c6d..17883073710c 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -138,6 +138,38 @@ static inline __u32 btf_type_info(int kind, int vlen, int kflag)
return (kflag << 31) | (kind << 24) | vlen;
}
[...]
