1 .. SPDX-License-Identifier: (GPL-2.0-only OR B
2
3 ================
4 bpftool-btf
5 ================
6 ----------------------------------------------
7 tool for inspection of BTF data
8 ----------------------------------------------
9
10 :Manual section: 8
11
12 .. include:: substitutions.rst
13
14 SYNOPSIS
15 ========
16
17 **bpftool** [*OPTIONS*] **btf** *COMMAND*
18
19 *OPTIONS* := { |COMMON_OPTIONS| | { **-B** | *
20
21 *COMMANDS* := { **dump** | **help** }
22
23 BTF COMMANDS
24 =============
25
26 | **bpftool** **btf** { **show** | **list** }
27 | **bpftool** **btf dump** *BTF_SRC* [**format
28 | **bpftool** **btf help**
29 |
30 | *BTF_SRC* := { **id** *BTF_ID* | **prog** *P
31 | *FORMAT* := { **raw** | **c** [**unsorted**]
32 | *MAP* := { **id** *MAP_ID* | **pinned** *FIL
33 | *PROG* := { **id** *PROG_ID* | **pinned** *F
34
35 DESCRIPTION
36 ===========
37 bpftool btf { show | list } [id *BTF_ID*]
38 Show information about loaded BTF objects.
39 information only about given BTF object, o
40 currently loaded on the system.
41
42 Since Linux 5.8 bpftool is able to discove
43 that hold open file descriptors (FDs) agai
44 bpftool will automatically emit this infor
45
46 bpftool btf dump *BTF_SRC*
47 Dump BTF entries from a given *BTF_SRC*.
48
49 When **id** is specified, BTF object with
50 its BTF types emitted.
51
52 When **map** is provided, it's expected th
53 with BTF types describing key and value. I
54 dump only BTF type(s) associated with key
55 both key and value (**kv**), or all BTF ty
56 object (**all**). If not specified, **kv**
57
58 When **prog** is provided, it's expected t
59 object with BTF types.
60
61 When specifying *FILE*, an ELF file is exp
62 with well-defined BTF binary format data,
63 pahole.
64
65 **format** option can be used to override
66 (**raw**) or C-syntax (**c**) output forma
67 formatting, the output is sorted by defaul
68 to avoid sorting the output.
69
70 bpftool btf help
71 Print short help message.
72
73 OPTIONS
74 =======
75 .. include:: common_options.rst
76
77 -B, --base-btf *FILE*
78 Pass a base BTF object. Base BTF objects a
79 objects for kernel modules. To avoid dupli
80 required by modules, BTF objects for modul
81 built incrementally on top of the kernel (
82 base BTF reference should usually point to
83
84 When the main BTF object to process (for e
85 dump) is passed as a *FILE*, bpftool attem
86 for the base object, and passing this opti
87 BTF object is passed through other handles
88 necessary.
89
90 EXAMPLES
91 ========
92 **# bpftool btf dump id 1226**
93
94 ::
95
96 [1] PTR '(anon)' type_id=2
97 [2] STRUCT 'dummy_tracepoint_args' size=16 v
98 'pad' type_id=3 bits_offset=0
99 'sock' type_id=4 bits_offset=64
100 [3] INT 'long long unsigned int' size=8 bits
101 [4] PTR '(anon)' type_id=5
102 [5] FWD 'sock' fwd_kind=union
103
104 This gives an example of default output for al
105
106 **$ cat prog.c**
107
108 ::
109
110 struct fwd_struct;
111
112 enum my_enum {
113 VAL1 = 3,
114 VAL2 = 7,
115 };
116
117 typedef struct my_struct my_struct_t;
118
119 struct my_struct {
120 const unsigned int const_int_field;
121 int bitfield_field: 4;
122 char arr_field[16];
123 const struct fwd_struct *restrict fw
124 enum my_enum enum_field;
125 volatile my_struct_t *typedef_ptr_fi
126 };
127
128 union my_union {
129 int a;
130 struct my_struct b;
131 };
132
133 struct my_struct struct_global_var __attribu
134 .bitfield_field = 3,
135 .enum_field = VAL1,
136 };
137 int global_var __attribute__((section("data_
138
139 __attribute__((noinline))
140 int my_func(union my_union *arg1, int arg2)
141 {
142 static int static_var __attribute__(
143 static_var++;
144 return static_var;
145 }
146
147 **$ bpftool btf dump file prog.o**
148
149 ::
150
151 [1] PTR '(anon)' type_id=2
152 [2] UNION 'my_union' size=48 vlen=2
153 'a' type_id=3 bits_offset=0
154 'b' type_id=4 bits_offset=0
155 [3] INT 'int' size=4 bits_offset=0 nr_bits=3
156 [4] STRUCT 'my_struct' size=48 vlen=6
157 'const_int_field' type_id=5 bits_off
158 'bitfield_field' type_id=3 bits_offs
159 'arr_field' type_id=8 bits_offset=40
160 'fwd_field' type_id=10 bits_offset=1
161 'enum_field' type_id=14 bits_offset=
162 'typedef_ptr_field' type_id=15 bits_
163 [5] CONST '(anon)' type_id=6
164 [6] INT 'unsigned int' size=4 bits_offset=0
165 [7] INT 'char' size=1 bits_offset=0 nr_bits=
166 [8] ARRAY '(anon)' type_id=7 index_type_id=9
167 [9] INT '__ARRAY_SIZE_TYPE__' size=4 bits_of
168 [10] RESTRICT '(anon)' type_id=11
169 [11] PTR '(anon)' type_id=12
170 [12] CONST '(anon)' type_id=13
171 [13] FWD 'fwd_struct' fwd_kind=union
172 [14] ENUM 'my_enum' size=4 vlen=2
173 'VAL1' val=3
174 'VAL2' val=7
175 [15] PTR '(anon)' type_id=16
176 [16] VOLATILE '(anon)' type_id=17
177 [17] TYPEDEF 'my_struct_t' type_id=4
178 [18] FUNC_PROTO '(anon)' ret_type_id=3 vlen=
179 'arg1' type_id=1
180 'arg2' type_id=3
181 [19] FUNC 'my_func' type_id=18
182 [20] VAR 'struct_global_var' type_id=4, link
183 [21] VAR 'global_var' type_id=3, linkage=glo
184 [22] VAR 'my_func.static_var' type_id=3, lin
185 [23] DATASEC 'data_sec' size=0 vlen=3
186 type_id=20 offset=0 size=48
187 type_id=21 offset=0 size=4
188 type_id=22 offset=52 size=4
189
190 The following commands print BTF types associa
191 value, both key and value, and all BTF types,
192 key and value types will be printed.
193
194 **# bpftool btf dump map id 123 key**
195
196 ::
197
198 [39] TYPEDEF 'u32' type_id=37
199
200 **# bpftool btf dump map id 123 value**
201
202 ::
203
204 [86] PTR '(anon)' type_id=87
205
206 **# bpftool btf dump map id 123 kv**
207
208 ::
209
210 [39] TYPEDEF 'u32' type_id=37
211 [86] PTR '(anon)' type_id=87
212
213 **# bpftool btf dump map id 123 all**
214
215 ::
216
217 [1] PTR '(anon)' type_id=0
218 .
219 .
220 .
221 [2866] ARRAY '(anon)' type_id=52 index_type_
222
223 All the standard ways to specify map or progra
224
225 **# bpftool btf dump map id 123**
226
227 **# bpftool btf dump map pinned /sys/fs/bpf/ma
228
229 **# bpftool btf dump prog id 456**
230
231 **# bpftool btf dump prog tag b88e0a09b1d9759d
232
233 **# bpftool btf dump prog pinned /sys/fs/bpf/p
234
235 |
236 | **# bpftool btf dump file /sys/kernel/btf/i2
237 | (or)
238 | **# I2C_SMBUS_ID=$(bpftool btf show -p | jq
239 | **# bpftool btf dump id ${I2C_SMBUS_ID} -B /
240
241 ::
242
243 [104848] STRUCT 'i2c_smbus_alert' size=40 vl
244 'alert' type_id=393 bits_offset=0
245 'ara' type_id=56050 bits_offset=256
246 [104849] STRUCT 'alert_data' size=12 vlen=3
247 'addr' type_id=16 bits_offset=0
248 'type' type_id=56053 bits_offset=32
249 'data' type_id=7 bits_offset=64
250 [104850] PTR '(anon)' type_id=104848
251 [104851] PTR '(anon)' type_id=104849
252 [104852] FUNC 'i2c_register_spd' type_id=847
253 [104853] FUNC 'smbalert_driver_init' type_id
254 [104854] FUNC_PROTO '(anon)' ret_type_id=18
255 'ara' type_id=56050
256 [104855] FUNC 'i2c_handle_smbus_alert' type_
257 [104856] FUNC 'smbalert_remove' type_id=1048
258 [104857] FUNC_PROTO '(anon)' ret_type_id=18
259 'ara' type_id=56050
260 'id' type_id=56056
261 [104858] FUNC 'smbalert_probe' type_id=10485
262 [104859] FUNC 'smbalert_work' type_id=9695 l
263 [104860] FUNC 'smbus_alert' type_id=71367 li
264 [104861] FUNC 'smbus_do_alert' type_id=84827
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