1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
|
================
bpftool-btf
================
-------------------------------------------------------------------------------
tool for inspection of BTF data
-------------------------------------------------------------------------------
:Manual section: 8
SYNOPSIS
========
**bpftool** [*OPTIONS*] **btf** *COMMAND*
*OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] }
*COMMANDS* := { **dump** | **help** }
BTF COMMANDS
=============
| **bpftool** **btf** { **show** | **list** } [**id** *BTF_ID*]
| **bpftool** **btf dump** *BTF_SRC* [**format** *FORMAT*]
| **bpftool** **btf help**
|
| *BTF_SRC* := { **id** *BTF_ID* | **prog** *PROG* | **map** *MAP* [{**key** | **value** | **kv** | **all**}] | **file** *FILE* }
| *FORMAT* := { **raw** | **c** }
| *MAP* := { **id** *MAP_ID* | **pinned** *FILE* }
| *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* }
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*.
When **id** is specified, BTF object with that ID will be
loaded and all its BTF types emitted.
When **map** is provided, it's expected that map has
associated BTF object with BTF types describing key and
value. It's possible to select whether to dump only BTF
type(s) associated with key (**key**), value (**value**),
both key and value (**kv**), or all BTF types present in
associated BTF object (**all**). If not specified, **kv**
is assumed.
When **prog** is provided, it's expected that program has
associated BTF object with BTF types.
When specifying *FILE*, an ELF file is expected, containing
.BTF section with well-defined BTF binary format data,
typically produced by clang or pahole.
**format** option can be used to override default (raw)
output format. Raw (**raw**) or C-syntax (**c**) output
formats are supported.
**bpftool btf help**
Print short help message.
OPTIONS
=======
-h, --help
Print short generic help message (similar to **bpftool help**).
-V, --version
Print version number (similar to **bpftool version**).
-j, --json
Generate JSON output. For commands that cannot produce JSON, this
option has no effect.
-p, --pretty
Generate human-readable JSON output. Implies **-j**.
-d, --debug
Print all logs available from libbpf, including debug-level
information.
EXAMPLES
========
**# bpftool btf dump id 1226**
::
[1] PTR '(anon)' type_id=2
[2] STRUCT 'dummy_tracepoint_args' size=16 vlen=2
'pad' type_id=3 bits_offset=0
'sock' type_id=4 bits_offset=64
[3] INT 'long long unsigned int' size=8 bits_offset=0 nr_bits=64 encoding=(none)
[4] PTR '(anon)' type_id=5
[5] FWD 'sock' fwd_kind=union
This gives an example of default output for all supported BTF kinds.
**$ cat prog.c**
::
struct fwd_struct;
enum my_enum {
VAL1 = 3,
VAL2 = 7,
};
typedef struct my_struct my_struct_t;
struct my_struct {
const unsigned int const_int_field;
int bitfield_field: 4;
char arr_field[16];
const struct fwd_struct *restrict fwd_field;
enum my_enum enum_field;
volatile my_struct_t *typedef_ptr_field;
};
union my_union {
int a;
struct my_struct b;
};
struct my_struct struct_global_var __attribute__((section("data_sec"))) = {
.bitfield_field = 3,
.enum_field = VAL1,
};
int global_var __attribute__((section("data_sec"))) = 7;
__attribute__((noinline))
int my_func(union my_union *arg1, int arg2)
{
static int static_var __attribute__((section("data_sec"))) = 123;
static_var++;
return static_var;
}
**$ bpftool btf dump file prog.o**
::
[1] PTR '(anon)' type_id=2
[2] UNION 'my_union' size=48 vlen=2
'a' type_id=3 bits_offset=0
'b' type_id=4 bits_offset=0
[3] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED
[4] STRUCT 'my_struct' size=48 vlen=6
'const_int_field' type_id=5 bits_offset=0
'bitfield_field' type_id=3 bits_offset=32 bitfield_size=4
'arr_field' type_id=8 bits_offset=40
'fwd_field' type_id=10 bits_offset=192
'enum_field' type_id=14 bits_offset=256
'typedef_ptr_field' type_id=15 bits_offset=320
[5] CONST '(anon)' type_id=6
[6] INT 'unsigned int' size=4 bits_offset=0 nr_bits=32 encoding=(none)
[7] INT 'char' size=1 bits_offset=0 nr_bits=8 encoding=SIGNED
[8] ARRAY '(anon)' type_id=7 index_type_id=9 nr_elems=16
[9] INT '__ARRAY_SIZE_TYPE__' size=4 bits_offset=0 nr_bits=32 encoding=(none)
[10] RESTRICT '(anon)' type_id=11
[11] PTR '(anon)' type_id=12
[12] CONST '(anon)' type_id=13
[13] FWD 'fwd_struct' fwd_kind=union
[14] ENUM 'my_enum' size=4 vlen=2
'VAL1' val=3
'VAL2' val=7
[15] PTR '(anon)' type_id=16
[16] VOLATILE '(anon)' type_id=17
[17] TYPEDEF 'my_struct_t' type_id=4
[18] FUNC_PROTO '(anon)' ret_type_id=3 vlen=2
'arg1' type_id=1
'arg2' type_id=3
[19] FUNC 'my_func' type_id=18
[20] VAR 'struct_global_var' type_id=4, linkage=global-alloc
[21] VAR 'global_var' type_id=3, linkage=global-alloc
[22] VAR 'my_func.static_var' type_id=3, linkage=static
[23] DATASEC 'data_sec' size=0 vlen=3
type_id=20 offset=0 size=48
type_id=21 offset=0 size=4
type_id=22 offset=52 size=4
The following commands print BTF types associated with specified map's key,
value, both key and value, and all BTF types, respectively. By default, both
key and value types will be printed.
**# bpftool btf dump map id 123 key**
::
[39] TYPEDEF 'u32' type_id=37
**# bpftool btf dump map id 123 value**
::
[86] PTR '(anon)' type_id=87
**# bpftool btf dump map id 123 kv**
::
[39] TYPEDEF 'u32' type_id=37
[86] PTR '(anon)' type_id=87
**# bpftool btf dump map id 123 all**
::
[1] PTR '(anon)' type_id=0
.
.
.
[2866] ARRAY '(anon)' type_id=52 index_type_id=51 nr_elems=4
All the standard ways to specify map or program are supported:
**# bpftool btf dump map id 123**
**# bpftool btf dump map pinned /sys/fs/bpf/map_name**
**# bpftool btf dump prog id 456**
**# bpftool btf dump prog tag b88e0a09b1d9759d**
**# bpftool btf dump prog pinned /sys/fs/bpf/prog_name**
SEE ALSO
========
**bpf**\ (2),
**bpf-helpers**\ (7),
**bpftool**\ (8),
**bpftool-btf**\ (8),
**bpftool-cgroup**\ (8),
**bpftool-feature**\ (8),
**bpftool-gen**\ (8),
**bpftool-iter**\ (8),
**bpftool-link**\ (8),
**bpftool-map**\ (8),
**bpftool-net**\ (8),
**bpftool-perf**\ (8),
**bpftool-prog**\ (8),
**bpftool-struct_ops**\ (8)
|
