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tools/bpf: refactor to implement btf_get_from_id() in lib/bpf

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The function get_btf() is implemented in tools/bpf/bpftool/map.c
to get a btf structure given a map_info. This patch
refactored this function to be function btf_get_from_id()
in tools/lib/bpf so that it can be used later.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song 2018-11-19 15:29:18 -08:00 committed by Alexei Starovoitov
parent 9ce6ae22c8
commit d7f5b5e051
3 changed files with 72 additions and 66 deletions
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68
tools/bpf/bpftool/map.c
View File

@ -215,70 +215,6 @@ err_end_obj:
return ret;
}
static int get_btf(struct bpf_map_info *map_info, struct btf **btf)
{
struct bpf_btf_info btf_info = { 0 };
__u32 len = sizeof(btf_info);
__u32 last_size;
int btf_fd;
void *ptr;
int err;
err = 0;
*btf = NULL;
btf_fd = bpf_btf_get_fd_by_id(map_info->btf_id);
if (btf_fd < 0)
return 0;
/* we won't know btf_size until we call bpf_obj_get_info_by_fd(). so
* let's start with a sane default - 4KiB here - and resize it only if
* bpf_obj_get_info_by_fd() needs a bigger buffer.
*/
btf_info.btf_size = 4096;
last_size = btf_info.btf_size;
ptr = malloc(last_size);
if (!ptr) {
err = -ENOMEM;
goto exit_free;
}
bzero(ptr, last_size);
btf_info.btf = ptr_to_u64(ptr);
err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
if (!err && btf_info.btf_size > last_size) {
void *temp_ptr;
last_size = btf_info.btf_size;
temp_ptr = realloc(ptr, last_size);
if (!temp_ptr) {
err = -ENOMEM;
goto exit_free;
}
ptr = temp_ptr;
bzero(ptr, last_size);
btf_info.btf = ptr_to_u64(ptr);
err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
}
if (err || btf_info.btf_size > last_size) {
err = errno;
goto exit_free;
}
*btf = btf__new((__u8 *)btf_info.btf, btf_info.btf_size, NULL);
if (IS_ERR(*btf)) {
err = PTR_ERR(*btf);
*btf = NULL;
}
exit_free:
close(btf_fd);
free(ptr);
return err;
}
static json_writer_t *get_btf_writer(void)
{
json_writer_t *jw = jsonw_new(stdout);
@ -775,7 +711,7 @@ static int do_dump(int argc, char **argv)
prev_key = NULL;
err = get_btf(&info, &btf);
err = btf_get_from_id(info.btf_id, &btf);
if (err) {
p_err("failed to get btf");
goto exit_free;
@ -919,7 +855,7 @@ static int do_lookup(int argc, char **argv)
}
/* here means bpf_map_lookup_elem() succeeded */
err = get_btf(&info, &btf);
err = btf_get_from_id(info.btf_id, &btf);
if (err) {
p_err("failed to get btf");
goto exit_free;

69
tools/lib/bpf/btf.c
View File

@ -49,6 +49,11 @@ struct bpf_func_info_min {
__u32 type_id;
};
static inline __u64 ptr_to_u64(const void *ptr)
{
return (__u64) (unsigned long) ptr;
}
static int btf_add_type(struct btf *btf, struct btf_type *t)
{
if (btf->types_size - btf->nr_types < 2) {
@ -410,6 +415,70 @@ const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
return NULL;
}
int btf_get_from_id(__u32 id, struct btf **btf)
{
struct bpf_btf_info btf_info = { 0 };
__u32 len = sizeof(btf_info);
__u32 last_size;
int btf_fd;
void *ptr;
int err;
err = 0;
*btf = NULL;
btf_fd = bpf_btf_get_fd_by_id(id);
if (btf_fd < 0)
return 0;
/* we won't know btf_size until we call bpf_obj_get_info_by_fd(). so
* let's start with a sane default - 4KiB here - and resize it only if
* bpf_obj_get_info_by_fd() needs a bigger buffer.
*/
btf_info.btf_size = 4096;
last_size = btf_info.btf_size;
ptr = malloc(last_size);
if (!ptr) {
err = -ENOMEM;
goto exit_free;
}
bzero(ptr, last_size);
btf_info.btf = ptr_to_u64(ptr);
err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
if (!err && btf_info.btf_size > last_size) {
void *temp_ptr;
last_size = btf_info.btf_size;
temp_ptr = realloc(ptr, last_size);
if (!temp_ptr) {
err = -ENOMEM;
goto exit_free;
}
ptr = temp_ptr;
bzero(ptr, last_size);
btf_info.btf = ptr_to_u64(ptr);
err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
}
if (err || btf_info.btf_size > last_size) {
err = errno;
goto exit_free;
}
*btf = btf__new((__u8 *)btf_info.btf, btf_info.btf_size, NULL);
if (IS_ERR(*btf)) {
err = PTR_ERR(*btf);
*btf = NULL;
}
exit_free:
close(btf_fd);
free(ptr);
return err;
}
static int btf_ext_validate_func_info(const void *finfo, __u32 size,
btf_print_fn_t err_log)
{

1
tools/lib/bpf/btf.h
View File

@ -69,6 +69,7 @@ LIBBPF_API __s64 btf__resolve_size(const struct btf *btf, __u32 type_id);
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);
struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log);
void btf_ext__free(struct btf_ext *btf_ext);