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Merge branch 'libbpf-btf_ext'
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Yonghong Song says:

====================
This patch set exposed a few functions in libbpf.
All these newly added API functions are helpful for
JIT based bpf compilation where .BTF and .BTF.ext
are available as in-memory data blobs.

Patch #1 exposed several btf_ext__* API functions which
are used to handle .BTF.ext ELF sections.
Patch #2 refactored the function bpf_map_find_btf_info()
and exposed API function btf__get_map_kv_tids() to
retrieve the map key/value type id's generated by
bpf program through BPF_ANNOTATE_KV_PAIR macro.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Alexei Starovoitov committed Feb 4, 2019
2 parents 7e8a590 + 96408c4 commit 1728b11
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Showing 4 changed files with 105 additions and 75 deletions.
73 changes: 73 additions & 0 deletions tools/lib/bpf/btf.c
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/* Copyright (c) 2018 Facebook */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
Expand Down Expand Up @@ -504,6 +505,78 @@ int btf__get_from_id(__u32 id, struct btf **btf)
return err;
}

int btf__get_map_kv_tids(const struct btf *btf, char *map_name,
__u32 expected_key_size, __u32 expected_value_size,
__u32 *key_type_id, __u32 *value_type_id)
{
const struct btf_type *container_type;
const struct btf_member *key, *value;
const size_t max_name = 256;
char container_name[max_name];
__s64 key_size, value_size;
__s32 container_id;

if (snprintf(container_name, max_name, "____btf_map_%s", map_name) ==
max_name) {
pr_warning("map:%s length of '____btf_map_%s' is too long\n",
map_name, map_name);
return -EINVAL;
}

container_id = btf__find_by_name(btf, container_name);
if (container_id < 0) {
pr_warning("map:%s container_name:%s cannot be found in BTF. Missing BPF_ANNOTATE_KV_PAIR?\n",
map_name, container_name);
return container_id;
}

container_type = btf__type_by_id(btf, container_id);
if (!container_type) {
pr_warning("map:%s cannot find BTF type for container_id:%u\n",
map_name, container_id);
return -EINVAL;
}

if (BTF_INFO_KIND(container_type->info) != BTF_KIND_STRUCT ||
BTF_INFO_VLEN(container_type->info) < 2) {
pr_warning("map:%s container_name:%s is an invalid container struct\n",
map_name, container_name);
return -EINVAL;
}

key = (struct btf_member *)(container_type + 1);
value = key + 1;

key_size = btf__resolve_size(btf, key->type);
if (key_size < 0) {
pr_warning("map:%s invalid BTF key_type_size\n", map_name);
return key_size;
}

if (expected_key_size != key_size) {
pr_warning("map:%s btf_key_type_size:%u != map_def_key_size:%u\n",
map_name, (__u32)key_size, expected_key_size);
return -EINVAL;
}

value_size = btf__resolve_size(btf, value->type);
if (value_size < 0) {
pr_warning("map:%s invalid BTF value_type_size\n", map_name);
return value_size;
}

if (expected_value_size != value_size) {
pr_warning("map:%s btf_value_type_size:%u != map_def_value_size:%u\n",
map_name, (__u32)value_size, expected_value_size);
return -EINVAL;
}

*key_type_id = key->type;
*value_type_id = value->type;

return 0;
}

struct btf_ext_sec_copy_param {
__u32 off;
__u32 len;
Expand Down
28 changes: 16 additions & 12 deletions tools/lib/bpf/btf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -66,19 +66,23 @@ LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id);
LIBBPF_API int btf__fd(const struct btf *btf);
LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);
LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, char *map_name,
__u32 expected_key_size,
__u32 expected_value_size,
__u32 *key_type_id, __u32 *value_type_id);

struct btf_ext *btf_ext__new(__u8 *data, __u32 size);
void btf_ext__free(struct btf_ext *btf_ext);
int btf_ext__reloc_func_info(const struct btf *btf,
const struct btf_ext *btf_ext,
const char *sec_name, __u32 insns_cnt,
void **func_info, __u32 *func_info_len);
int btf_ext__reloc_line_info(const struct btf *btf,
const struct btf_ext *btf_ext,
const char *sec_name, __u32 insns_cnt,
void **line_info, __u32 *cnt);
__u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
__u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);
LIBBPF_API struct btf_ext *btf_ext__new(__u8 *data, __u32 size);
LIBBPF_API void btf_ext__free(struct btf_ext *btf_ext);
LIBBPF_API int btf_ext__reloc_func_info(const struct btf *btf,
const struct btf_ext *btf_ext,
const char *sec_name, __u32 insns_cnt,
void **func_info, __u32 *cnt);
LIBBPF_API int btf_ext__reloc_line_info(const struct btf *btf,
const struct btf_ext *btf_ext,
const char *sec_name, __u32 insns_cnt,
void **line_info, __u32 *cnt);
LIBBPF_API __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
LIBBPF_API __u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);

#ifdef __cplusplus
} /* extern "C" */
Expand Down
72 changes: 9 additions & 63 deletions tools/lib/bpf/libbpf.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1056,72 +1056,18 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,

static int bpf_map_find_btf_info(struct bpf_map *map, const struct btf *btf)
{
const struct btf_type *container_type;
const struct btf_member *key, *value;
struct bpf_map_def *def = &map->def;
const size_t max_name = 256;
char container_name[max_name];
__s64 key_size, value_size;
__s32 container_id;

if (snprintf(container_name, max_name, "____btf_map_%s", map->name) ==
max_name) {
pr_warning("map:%s length of '____btf_map_%s' is too long\n",
map->name, map->name);
return -EINVAL;
}

container_id = btf__find_by_name(btf, container_name);
if (container_id < 0) {
pr_debug("map:%s container_name:%s cannot be found in BTF. Missing BPF_ANNOTATE_KV_PAIR?\n",
map->name, container_name);
return container_id;
}

container_type = btf__type_by_id(btf, container_id);
if (!container_type) {
pr_warning("map:%s cannot find BTF type for container_id:%u\n",
map->name, container_id);
return -EINVAL;
}

if (BTF_INFO_KIND(container_type->info) != BTF_KIND_STRUCT ||
BTF_INFO_VLEN(container_type->info) < 2) {
pr_warning("map:%s container_name:%s is an invalid container struct\n",
map->name, container_name);
return -EINVAL;
}

key = (struct btf_member *)(container_type + 1);
value = key + 1;

key_size = btf__resolve_size(btf, key->type);
if (key_size < 0) {
pr_warning("map:%s invalid BTF key_type_size\n",
map->name);
return key_size;
}

if (def->key_size != key_size) {
pr_warning("map:%s btf_key_type_size:%u != map_def_key_size:%u\n",
map->name, (__u32)key_size, def->key_size);
return -EINVAL;
}

value_size = btf__resolve_size(btf, value->type);
if (value_size < 0) {
pr_warning("map:%s invalid BTF value_type_size\n", map->name);
return value_size;
}
__u32 key_type_id, value_type_id;
int ret;

if (def->value_size != value_size) {
pr_warning("map:%s btf_value_type_size:%u != map_def_value_size:%u\n",
map->name, (__u32)value_size, def->value_size);
return -EINVAL;
}
ret = btf__get_map_kv_tids(btf, map->name, def->key_size,
def->value_size, &key_type_id,
&value_type_id);
if (ret)
return ret;

map->btf_key_type_id = key->type;
map->btf_value_type_id = value->type;
map->btf_key_type_id = key_type_id;
map->btf_value_type_id = value_type_id;

return 0;
}
Expand Down
7 changes: 7 additions & 0 deletions tools/lib/bpf/libbpf.map
View file
Original file line number Diff line number Diff line change
Expand Up @@ -133,4 +133,11 @@ LIBBPF_0.0.2 {
bpf_map_lookup_elem_flags;
bpf_object__find_map_fd_by_name;
bpf_get_link_xdp_id;
btf__get_map_kv_tids;
btf_ext__free;
btf_ext__func_info_rec_size;
btf_ext__line_info_rec_size;
btf_ext__new;
btf_ext__reloc_func_info;
btf_ext__reloc_line_info;
} LIBBPF_0.0.1;

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