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Message-ID: <20190628152539.3014719-2-andriin@fb.com>
Date: Fri, 28 Jun 2019 08:25:36 -0700
From: Andrii Nakryiko <andriin@...com>
To: <andrii.nakryiko@...il.com>, <ast@...com>, <daniel@...earbox.net>,
<bpf@...r.kernel.org>, <netdev@...r.kernel.org>,
<songliubraving@...com>
CC: Andrii Nakryiko <andriin@...com>
Subject: [PATCH v2 bpf-next 1/4] libbpf: capture value in BTF type info for BTF-defined map defs
Change BTF-defined map definitions to capture compile-time integer
values as part of BTF type definition, to avoid split of key/value type
information and actual type/size/flags initialization for maps.
Signed-off-by: Andrii Nakryiko <andriin@...com>
---
tools/lib/bpf/libbpf.c | 58 ++++++++++++++++++++----------------------
1 file changed, 28 insertions(+), 30 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 6e6ebef11ba3..9e099ecb2c2b 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1028,40 +1028,40 @@ static const struct btf_type *skip_mods_and_typedefs(const struct btf *btf,
}
}
-static bool get_map_field_int(const char *map_name,
- const struct btf *btf,
+/*
+ * Fetch integer attribute of BTF map definition. Such attributes are
+ * represented using a pointer to an array, in which dimensionality of array
+ * encodes specified integer value. E.g., int (*type)[BPF_MAP_TYPE_ARRAY];
+ * encodes `type => BPF_MAP_TYPE_ARRAY` key/value pair completely using BTF
+ * type definition, while using only sizeof(void *) space in ELF data section.
+ */
+static bool get_map_field_int(const char *map_name, const struct btf *btf,
const struct btf_type *def,
- const struct btf_member *m,
- const void *data, __u32 *res) {
+ const struct btf_member *m, __u32 *res) {
const struct btf_type *t = skip_mods_and_typedefs(btf, m->type);
const char *name = btf__name_by_offset(btf, m->name_off);
- __u32 int_info = *(const __u32 *)(const void *)(t + 1);
+ const struct btf_array *arr_info;
+ const struct btf_type *arr_t;
- if (BTF_INFO_KIND(t->info) != BTF_KIND_INT) {
- pr_warning("map '%s': attr '%s': expected INT, got %u.\n",
+ if (BTF_INFO_KIND(t->info) != BTF_KIND_PTR) {
+ pr_warning("map '%s': attr '%s': expected PTR, got %u.\n",
map_name, name, BTF_INFO_KIND(t->info));
return false;
}
- if (t->size != 4 || BTF_INT_BITS(int_info) != 32 ||
- BTF_INT_OFFSET(int_info)) {
- pr_warning("map '%s': attr '%s': expected 32-bit non-bitfield integer, "
- "got %u-byte (%d-bit) one with bit offset %d.\n",
- map_name, name, t->size, BTF_INT_BITS(int_info),
- BTF_INT_OFFSET(int_info));
- return false;
- }
- if (BTF_INFO_KFLAG(def->info) && BTF_MEMBER_BITFIELD_SIZE(m->offset)) {
- pr_warning("map '%s': attr '%s': bitfield is not supported.\n",
- map_name, name);
+
+ arr_t = btf__type_by_id(btf, t->type);
+ if (!arr_t) {
+ pr_warning("map '%s': attr '%s': type [%u] not found.\n",
+ map_name, name, t->type);
return false;
}
- if (m->offset % 32) {
- pr_warning("map '%s': attr '%s': unaligned fields are not supported.\n",
- map_name, name);
+ if (BTF_INFO_KIND(arr_t->info) != BTF_KIND_ARRAY) {
+ pr_warning("map '%s': attr '%s': expected ARRAY, got %u.\n",
+ map_name, name, BTF_INFO_KIND(arr_t->info));
return false;
}
-
- *res = *(const __u32 *)(data + m->offset / 8);
+ arr_info = (const void *)(arr_t + 1);
+ *res = arr_info->nelems;
return true;
}
@@ -1074,7 +1074,6 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
const struct btf_var_secinfo *vi;
const struct btf_var *var_extra;
const struct btf_member *m;
- const void *def_data;
const char *map_name;
struct bpf_map *map;
int vlen, i;
@@ -1131,7 +1130,6 @@ 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);
- def_data = data->d_buf + vi->offset;
vlen = BTF_INFO_VLEN(def->info);
m = (const void *)(def + 1);
for (i = 0; i < vlen; i++, m++) {
@@ -1144,19 +1142,19 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
}
if (strcmp(name, "type") == 0) {
if (!get_map_field_int(map_name, obj->btf, def, m,
- def_data, &map->def.type))
+ &map->def.type))
return -EINVAL;
pr_debug("map '%s': found type = %u.\n",
map_name, map->def.type);
} else if (strcmp(name, "max_entries") == 0) {
if (!get_map_field_int(map_name, obj->btf, def, m,
- def_data, &map->def.max_entries))
+ &map->def.max_entries))
return -EINVAL;
pr_debug("map '%s': found max_entries = %u.\n",
map_name, map->def.max_entries);
} else if (strcmp(name, "map_flags") == 0) {
if (!get_map_field_int(map_name, obj->btf, def, m,
- def_data, &map->def.map_flags))
+ &map->def.map_flags))
return -EINVAL;
pr_debug("map '%s': found map_flags = %u.\n",
map_name, map->def.map_flags);
@@ -1164,7 +1162,7 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
__u32 sz;
if (!get_map_field_int(map_name, obj->btf, def, m,
- def_data, &sz))
+ &sz))
return -EINVAL;
pr_debug("map '%s': found key_size = %u.\n",
map_name, sz);
@@ -1207,7 +1205,7 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
__u32 sz;
if (!get_map_field_int(map_name, obj->btf, def, m,
- def_data, &sz))
+ &sz))
return -EINVAL;
pr_debug("map '%s': found value_size = %u.\n",
map_name, sz);
--
2.17.1
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