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tools: bpftool: implement "bpftool btf show|list" 

Add a "btf list" (alias: "btf show") subcommand to bpftool in order to
dump all BTF objects loaded on a system.

When running the command, hash tables are built in bpftool to retrieve
all the associations between BTF objects and BPF maps and programs. This
allows for printing all such associations when listing the BTF objects.

The command is added at the top of the subcommands for "bpftool btf", so
that typing only "bpftool btf" also comes down to listing the programs.
We could not have this with the previous command ("dump"), which
required a BTF object id, so it should not break any previous behaviour.
This also makes the "btf" command behaviour consistent with "prog" or
"map".

Bash completion is updated to use "bpftool btf" instead of "bpftool
prog" to list the BTF ids, as it looks more consistent.

Example output (plain):

    # bpftool btf show
    9: size 2989B  prog_ids 21  map_ids 15
    17: size 2847B  prog_ids 36  map_ids 30,29,28
    26: size 2847B

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Quentin Monnet 2019-08-20 10:31:54 +01:00 committed by Alexei Starovoitov
parent 09d7c2e32b
commit 4d374ba0bf
3 changed files with 363 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
tools/bpf/bpftool/Documentation/bpftool-btf.rst
View File

@ -19,6 +19,7 @@ SYNOPSIS
BTF COMMANDS
=============
| **bpftool** **btf** { **show** | **list** } [**id** *BTF_ID*]
| **bpftool** **btf dump** *BTF_SRC* [**format** *FORMAT*]
| **bpftool** **btf help**
|
@ -29,6 +30,12 @@ BTF COMMANDS
DESCRIPTION
===========
**bpftool btf { show | list }** [**id** *BTF_ID*]
Show information about loaded BTF objects. If a BTF ID is
specified, show information only about given BTF object,
otherwise list all BTF objects currently loaded on the
system.
**bpftool btf dump** *BTF_SRC*
Dump BTF entries from a given *BTF_SRC*.

20
tools/bpf/bpftool/bash-completion/bpftool
View File

@ -73,8 +73,8 @@ _bpftool_get_prog_tags()
_bpftool_get_btf_ids()
{
COMPREPLY+=( $( compgen -W "$( bpftool -jp prog 2>&1 | \
command sed -n 's/.*"btf_id": \(.*\),\?$/\1/p' )" -- "$cur" ) )
COMPREPLY+=( $( compgen -W "$( bpftool -jp btf 2>&1 | \
command sed -n 's/.*"id": \(.*\),$/\1/p' )" -- "$cur" ) )
}
_bpftool_get_obj_map_names()
@ -670,7 +670,7 @@ _bpftool()
map)
_bpftool_get_map_ids
;;
dump)
$command)
_bpftool_get_btf_ids
;;
esac
@ -698,9 +698,21 @@ _bpftool()
;;
esac
;;
show|list)
case $prev in
$command)
COMPREPLY+=( $( compgen -W "id" -- "$cur" ) )
;;
id)
_bpftool_get_btf_ids
;;
esac
return 0
;;
*)
[[ $prev == $object ]] && \
COMPREPLY=( $( compgen -W 'dump help' -- "$cur" ) )
COMPREPLY=( $( compgen -W 'dump help show list' \
-- "$cur" ) )
;;
esac
;;

342
tools/bpf/bpftool/btf.c
View File

@ -11,6 +11,7 @@
#include <bpf.h>
#include <libbpf.h>
#include <linux/btf.h>
#include <linux/hashtable.h>
#include "btf.h"
#include "json_writer.h"
@ -35,6 +36,16 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = {
[BTF_KIND_DATASEC] = "DATASEC",
};
struct btf_attach_table {
DECLARE_HASHTABLE(table, 16);
};
struct btf_attach_point {
__u32 obj_id;
__u32 btf_id;
struct hlist_node hash;
};
static const char *btf_int_enc_str(__u8 encoding)
{
switch (encoding) {
@ -522,6 +533,330 @@ static int do_dump(int argc, char **argv)
return err;
}
static int btf_parse_fd(int *argc, char ***argv)
{
unsigned int id;
char *endptr;
int fd;
if (!is_prefix(*argv[0], "id")) {
p_err("expected 'id', got: '%s'?", **argv);
return -1;
}
NEXT_ARGP();
id = strtoul(**argv, &endptr, 0);
if (*endptr) {
p_err("can't parse %s as ID", **argv);
return -1;
}
NEXT_ARGP();
fd = bpf_btf_get_fd_by_id(id);
if (fd < 0)
p_err("can't get BTF object by id (%u): %s",
id, strerror(errno));
return fd;
}
static void delete_btf_table(struct btf_attach_table *tab)
{
struct btf_attach_point *obj;
struct hlist_node *tmp;
unsigned int bkt;
hash_for_each_safe(tab->table, bkt, tmp, obj, hash) {
hash_del(&obj->hash);
free(obj);
}
}
static int
build_btf_type_table(struct btf_attach_table *tab, enum bpf_obj_type type,
void *info, __u32 *len)
{
static const char * const names[] = {
[BPF_OBJ_UNKNOWN] = "unknown",
[BPF_OBJ_PROG] = "prog",
[BPF_OBJ_MAP] = "map",
};
struct btf_attach_point *obj_node;
__u32 btf_id, id = 0;
int err;
int fd;
while (true) {
switch (type) {
case BPF_OBJ_PROG:
err = bpf_prog_get_next_id(id, &id);
break;
case BPF_OBJ_MAP:
err = bpf_map_get_next_id(id, &id);
break;
default:
err = -1;
p_err("unexpected object type: %d", type);
goto err_free;
}
if (err) {
if (errno == ENOENT) {
err = 0;
break;
}
p_err("can't get next %s: %s%s", names[type],
strerror(errno),
errno == EINVAL ? " -- kernel too old?" : "");
goto err_free;
}
switch (type) {
case BPF_OBJ_PROG:
fd = bpf_prog_get_fd_by_id(id);
break;
case BPF_OBJ_MAP:
fd = bpf_map_get_fd_by_id(id);
break;
default:
err = -1;
p_err("unexpected object type: %d", type);
goto err_free;
}
if (fd < 0) {
if (errno == ENOENT)
continue;
p_err("can't get %s by id (%u): %s", names[type], id,
strerror(errno));
err = -1;
goto err_free;
}
memset(info, 0, *len);
err = bpf_obj_get_info_by_fd(fd, info, len);
close(fd);
if (err) {
p_err("can't get %s info: %s", names[type],
strerror(errno));
goto err_free;
}
switch (type) {
case BPF_OBJ_PROG:
btf_id = ((struct bpf_prog_info *)info)->btf_id;
break;
case BPF_OBJ_MAP:
btf_id = ((struct bpf_map_info *)info)->btf_id;
break;
default:
err = -1;
p_err("unexpected object type: %d", type);
goto err_free;
}
if (!btf_id)
continue;
obj_node = calloc(1, sizeof(*obj_node));
if (!obj_node) {
p_err("failed to allocate memory: %s", strerror(errno));
goto err_free;
}
obj_node->obj_id = id;
obj_node->btf_id = btf_id;
hash_add(tab->table, &obj_node->hash, obj_node->btf_id);
}
return 0;
err_free:
delete_btf_table(tab);
return err;
}
static int
build_btf_tables(struct btf_attach_table *btf_prog_table,
struct btf_attach_table *btf_map_table)
{
struct bpf_prog_info prog_info;
__u32 prog_len = sizeof(prog_info);
struct bpf_map_info map_info;
__u32 map_len = sizeof(map_info);
int err = 0;
err = build_btf_type_table(btf_prog_table, BPF_OBJ_PROG, &prog_info,
&prog_len);
if (err)
return err;
err = build_btf_type_table(btf_map_table, BPF_OBJ_MAP, &map_info,
&map_len);
if (err) {
delete_btf_table(btf_prog_table);
return err;
}
return 0;
}
static void
show_btf_plain(struct bpf_btf_info *info, int fd,
struct btf_attach_table *btf_prog_table,
struct btf_attach_table *btf_map_table)
{
struct btf_attach_point *obj;
int n;
printf("%u: ", info->id);
printf("size %uB", info->btf_size);
n = 0;
hash_for_each_possible(btf_prog_table->table, obj, hash, info->id) {
if (obj->btf_id == info->id)
printf("%s%u", n++ == 0 ? " prog_ids " : ",",
obj->obj_id);
}
n = 0;
hash_for_each_possible(btf_map_table->table, obj, hash, info->id) {
if (obj->btf_id == info->id)
printf("%s%u", n++ == 0 ? " map_ids " : ",",
obj->obj_id);
}
printf("\n");
}
static void
show_btf_json(struct bpf_btf_info *info, int fd,
struct btf_attach_table *btf_prog_table,
struct btf_attach_table *btf_map_table)
{
struct btf_attach_point *obj;
jsonw_start_object(json_wtr); /* btf object */
jsonw_uint_field(json_wtr, "id", info->id);
jsonw_uint_field(json_wtr, "size", info->btf_size);
jsonw_name(json_wtr, "prog_ids");
jsonw_start_array(json_wtr); /* prog_ids */
hash_for_each_possible(btf_prog_table->table, obj, hash,
info->id) {
if (obj->btf_id == info->id)
jsonw_uint(json_wtr, obj->obj_id);
}
jsonw_end_array(json_wtr); /* prog_ids */
jsonw_name(json_wtr, "map_ids");
jsonw_start_array(json_wtr); /* map_ids */
hash_for_each_possible(btf_map_table->table, obj, hash,
info->id) {
if (obj->btf_id == info->id)
jsonw_uint(json_wtr, obj->obj_id);
}
jsonw_end_array(json_wtr); /* map_ids */
jsonw_end_object(json_wtr); /* btf object */
}
static int
show_btf(int fd, struct btf_attach_table *btf_prog_table,
struct btf_attach_table *btf_map_table)
{
struct bpf_btf_info info = {};
__u32 len = sizeof(info);
int err;
err = bpf_obj_get_info_by_fd(fd, &info, &len);
if (err) {
p_err("can't get BTF object info: %s", strerror(errno));
return -1;
}
if (json_output)
show_btf_json(&info, fd, btf_prog_table, btf_map_table);
else
show_btf_plain(&info, fd, btf_prog_table, btf_map_table);
return 0;
}
static int do_show(int argc, char **argv)
{
struct btf_attach_table btf_prog_table;
struct btf_attach_table btf_map_table;
int err, fd = -1;
__u32 id = 0;
if (argc == 2) {
fd = btf_parse_fd(&argc, &argv);
if (fd < 0)
return -1;
}
if (argc) {
if (fd >= 0)
close(fd);
return BAD_ARG();
}
hash_init(btf_prog_table.table);
hash_init(btf_map_table.table);
err = build_btf_tables(&btf_prog_table, &btf_map_table);
if (err) {
if (fd >= 0)
close(fd);
return err;
}
if (fd >= 0) {
err = show_btf(fd, &btf_prog_table, &btf_map_table);
close(fd);
goto exit_free;
}
if (json_output)
jsonw_start_array(json_wtr); /* root array */
while (true) {
err = bpf_btf_get_next_id(id, &id);
if (err) {
if (errno == ENOENT) {
err = 0;
break;
}
p_err("can't get next BTF object: %s%s",
strerror(errno),
errno == EINVAL ? " -- kernel too old?" : "");
err = -1;
break;
}
fd = bpf_btf_get_fd_by_id(id);
if (fd < 0) {
if (errno == ENOENT)
continue;
p_err("can't get BTF object by id (%u): %s",
id, strerror(errno));
err = -1;
break;
}
err = show_btf(fd, &btf_prog_table, &btf_map_table);
close(fd);
if (err)
break;
}
if (json_output)
jsonw_end_array(json_wtr); /* root array */
exit_free:
delete_btf_table(&btf_prog_table);
delete_btf_table(&btf_map_table);
return err;
}
static int do_help(int argc, char **argv)
{
if (json_output) {
@ -530,7 +865,8 @@ static int do_help(int argc, char **argv)
}
fprintf(stderr,
"Usage: %s btf dump BTF_SRC [format FORMAT]\n"
"Usage: %s btf { show | list } [id BTF_ID]\n"
" %s btf dump BTF_SRC [format FORMAT]\n"
" %s btf help\n"
"\n"
" BTF_SRC := { id BTF_ID | prog PROG | map MAP [{key | value | kv | all}] | file FILE }\n"
@ -539,12 +875,14 @@ static int do_help(int argc, char **argv)
" " HELP_SPEC_PROGRAM "\n"
" " HELP_SPEC_OPTIONS "\n"
"",
bin_name, bin_name);
bin_name, bin_name, bin_name);
return 0;
}
static const struct cmd cmds[] = {
{ "show", do_show },
{ "list", do_show },
{ "help", do_help },
{ "dump", do_dump },
{ 0 }