1 .. SPDX-License-Identifier: (GPL-2.0-only OR B <<
2 <<
3 ================ 1 ================
4 bpftool-btf 2 bpftool-btf
5 ================ 3 ================
6 ---------------------------------------------- 4 -------------------------------------------------------------------------------
7 tool for inspection of BTF data 5 tool for inspection of BTF data
8 ---------------------------------------------- 6 -------------------------------------------------------------------------------
9 7
10 :Manual section: 8 8 :Manual section: 8
11 9
12 .. include:: substitutions.rst <<
13 <<
14 SYNOPSIS 10 SYNOPSIS
15 ======== 11 ========
16 12
17 **bpftool** [*OPTIONS*] **btf** *COMMAND* !! 13 **bpftool** [*OPTIONS*] **btf** *COMMAND*
18 14
19 *OPTIONS* := { |COMMON_OPTIONS| | { **-B** | * !! 15 *OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] }
20 16
21 *COMMANDS* := { **dump** | **help** } !! 17 *COMMANDS* := { **dump** | **help** }
22 18
23 BTF COMMANDS 19 BTF COMMANDS
24 ============= 20 =============
25 21
26 | **bpftool** **btf** { **show** | **list** } !! 22 | **bpftool** **btf** { **show** | **list** } [**id** *BTF_ID*]
27 | **bpftool** **btf dump** *BTF_SRC* [**format !! 23 | **bpftool** **btf dump** *BTF_SRC* [**format** *FORMAT*]
28 | **bpftool** **btf help** !! 24 | **bpftool** **btf help**
29 | 25 |
30 | *BTF_SRC* := { **id** *BTF_ID* | **prog** *P !! 26 | *BTF_SRC* := { **id** *BTF_ID* | **prog** *PROG* | **map** *MAP* [{**key** | **value** | **kv** | **all**}] | **file** *FILE* }
31 | *FORMAT* := { **raw** | **c** [**unsorted**] !! 27 | *FORMAT* := { **raw** | **c** }
32 | *MAP* := { **id** *MAP_ID* | **pinned** *FIL !! 28 | *MAP* := { **id** *MAP_ID* | **pinned** *FILE* }
33 | *PROG* := { **id** *PROG_ID* | **pinned** *F !! 29 | *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* }
34 30
35 DESCRIPTION 31 DESCRIPTION
36 =========== 32 ===========
37 bpftool btf { show | list } [id *BTF_ID*] !! 33 **bpftool btf { show | list }** [**id** *BTF_ID*]
38 Show information about loaded BTF objects. !! 34 Show information about loaded BTF objects. If a BTF ID is
39 information only about given BTF object, o !! 35 specified, show information only about given BTF object,
40 currently loaded on the system. !! 36 otherwise list all BTF objects currently loaded on the
41 !! 37 system.
42 Since Linux 5.8 bpftool is able to discove !! 38
43 that hold open file descriptors (FDs) agai !! 39 **bpftool btf dump** *BTF_SRC*
44 bpftool will automatically emit this infor !! 40 Dump BTF entries from a given *BTF_SRC*.
45 !! 41
46 bpftool btf dump *BTF_SRC* !! 42 When **id** is specified, BTF object with that ID will be
47 Dump BTF entries from a given *BTF_SRC*. !! 43 loaded and all its BTF types emitted.
48 !! 44
49 When **id** is specified, BTF object with !! 45 When **map** is provided, it's expected that map has
50 its BTF types emitted. !! 46 associated BTF object with BTF types describing key and
51 !! 47 value. It's possible to select whether to dump only BTF
52 When **map** is provided, it's expected th !! 48 type(s) associated with key (**key**), value (**value**),
53 with BTF types describing key and value. I !! 49 both key and value (**kv**), or all BTF types present in
54 dump only BTF type(s) associated with key !! 50 associated BTF object (**all**). If not specified, **kv**
55 both key and value (**kv**), or all BTF ty !! 51 is assumed.
56 object (**all**). If not specified, **kv** !! 52
57 !! 53 When **prog** is provided, it's expected that program has
58 When **prog** is provided, it's expected t !! 54 associated BTF object with BTF types.
59 object with BTF types. !! 55
60 !! 56 When specifying *FILE*, an ELF file is expected, containing
61 When specifying *FILE*, an ELF file is exp !! 57 .BTF section with well-defined BTF binary format data,
62 with well-defined BTF binary format data, !! 58 typically produced by clang or pahole.
63 pahole. !! 59
64 !! 60 **format** option can be used to override default (raw)
65 **format** option can be used to override !! 61 output format. Raw (**raw**) or C-syntax (**c**) output
66 (**raw**) or C-syntax (**c**) output forma !! 62 formats are supported.
67 formatting, the output is sorted by defaul <<
68 to avoid sorting the output. <<
69 63
70 bpftool btf help !! 64 **bpftool btf help**
71 Print short help message. !! 65 Print short help message.
72 66
73 OPTIONS 67 OPTIONS
74 ======= 68 =======
75 .. include:: common_options.rst !! 69 -h, --help
>> 70 Print short generic help message (similar to **bpftool help**).
>> 71
>> 72 -V, --version
>> 73 Print version number (similar to **bpftool version**).
76 74
77 -B, --base-btf *FILE* !! 75 -j, --json
78 Pass a base BTF object. Base BTF objects a !! 76 Generate JSON output. For commands that cannot produce JSON, this
79 objects for kernel modules. To avoid dupli !! 77 option has no effect.
80 required by modules, BTF objects for modul !! 78
81 built incrementally on top of the kernel ( !! 79 -p, --pretty
82 base BTF reference should usually point to !! 80 Generate human-readable JSON output. Implies **-j**.
83 !! 81
84 When the main BTF object to process (for e !! 82 -d, --debug
85 dump) is passed as a *FILE*, bpftool attem !! 83 Print all logs available from libbpf, including debug-level
86 for the base object, and passing this opti !! 84 information.
87 BTF object is passed through other handles <<
88 necessary. <<
89 85
90 EXAMPLES 86 EXAMPLES
91 ======== 87 ========
92 **# bpftool btf dump id 1226** 88 **# bpftool btf dump id 1226**
93 <<
94 :: 89 ::
95 90
96 [1] PTR '(anon)' type_id=2 91 [1] PTR '(anon)' type_id=2
97 [2] STRUCT 'dummy_tracepoint_args' size=16 v 92 [2] STRUCT 'dummy_tracepoint_args' size=16 vlen=2
98 'pad' type_id=3 bits_offset=0 93 'pad' type_id=3 bits_offset=0
99 'sock' type_id=4 bits_offset=64 94 'sock' type_id=4 bits_offset=64
100 [3] INT 'long long unsigned int' size=8 bits 95 [3] INT 'long long unsigned int' size=8 bits_offset=0 nr_bits=64 encoding=(none)
101 [4] PTR '(anon)' type_id=5 96 [4] PTR '(anon)' type_id=5
102 [5] FWD 'sock' fwd_kind=union 97 [5] FWD 'sock' fwd_kind=union
103 98
104 This gives an example of default output for al 99 This gives an example of default output for all supported BTF kinds.
105 100
106 **$ cat prog.c** 101 **$ cat prog.c**
107 <<
108 :: 102 ::
109 103
110 struct fwd_struct; 104 struct fwd_struct;
111 105
112 enum my_enum { 106 enum my_enum {
113 VAL1 = 3, 107 VAL1 = 3,
114 VAL2 = 7, 108 VAL2 = 7,
115 }; 109 };
116 110
117 typedef struct my_struct my_struct_t; 111 typedef struct my_struct my_struct_t;
118 112
119 struct my_struct { 113 struct my_struct {
120 const unsigned int const_int_field; 114 const unsigned int const_int_field;
121 int bitfield_field: 4; 115 int bitfield_field: 4;
122 char arr_field[16]; 116 char arr_field[16];
123 const struct fwd_struct *restrict fw 117 const struct fwd_struct *restrict fwd_field;
124 enum my_enum enum_field; 118 enum my_enum enum_field;
125 volatile my_struct_t *typedef_ptr_fi 119 volatile my_struct_t *typedef_ptr_field;
126 }; 120 };
127 121
128 union my_union { 122 union my_union {
129 int a; 123 int a;
130 struct my_struct b; 124 struct my_struct b;
131 }; 125 };
132 126
133 struct my_struct struct_global_var __attribu 127 struct my_struct struct_global_var __attribute__((section("data_sec"))) = {
134 .bitfield_field = 3, 128 .bitfield_field = 3,
135 .enum_field = VAL1, 129 .enum_field = VAL1,
136 }; 130 };
137 int global_var __attribute__((section("data_ 131 int global_var __attribute__((section("data_sec"))) = 7;
138 132
139 __attribute__((noinline)) 133 __attribute__((noinline))
140 int my_func(union my_union *arg1, int arg2) 134 int my_func(union my_union *arg1, int arg2)
141 { 135 {
142 static int static_var __attribute__( 136 static int static_var __attribute__((section("data_sec"))) = 123;
143 static_var++; 137 static_var++;
144 return static_var; 138 return static_var;
145 } 139 }
146 140
147 **$ bpftool btf dump file prog.o** 141 **$ bpftool btf dump file prog.o**
148 <<
149 :: 142 ::
150 143
151 [1] PTR '(anon)' type_id=2 144 [1] PTR '(anon)' type_id=2
152 [2] UNION 'my_union' size=48 vlen=2 145 [2] UNION 'my_union' size=48 vlen=2
153 'a' type_id=3 bits_offset=0 146 'a' type_id=3 bits_offset=0
154 'b' type_id=4 bits_offset=0 147 'b' type_id=4 bits_offset=0
155 [3] INT 'int' size=4 bits_offset=0 nr_bits=3 148 [3] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED
156 [4] STRUCT 'my_struct' size=48 vlen=6 149 [4] STRUCT 'my_struct' size=48 vlen=6
157 'const_int_field' type_id=5 bits_off 150 'const_int_field' type_id=5 bits_offset=0
158 'bitfield_field' type_id=3 bits_offs 151 'bitfield_field' type_id=3 bits_offset=32 bitfield_size=4
159 'arr_field' type_id=8 bits_offset=40 152 'arr_field' type_id=8 bits_offset=40
160 'fwd_field' type_id=10 bits_offset=1 153 'fwd_field' type_id=10 bits_offset=192
161 'enum_field' type_id=14 bits_offset= 154 'enum_field' type_id=14 bits_offset=256
162 'typedef_ptr_field' type_id=15 bits_ 155 'typedef_ptr_field' type_id=15 bits_offset=320
163 [5] CONST '(anon)' type_id=6 156 [5] CONST '(anon)' type_id=6
164 [6] INT 'unsigned int' size=4 bits_offset=0 157 [6] INT 'unsigned int' size=4 bits_offset=0 nr_bits=32 encoding=(none)
165 [7] INT 'char' size=1 bits_offset=0 nr_bits= 158 [7] INT 'char' size=1 bits_offset=0 nr_bits=8 encoding=SIGNED
166 [8] ARRAY '(anon)' type_id=7 index_type_id=9 159 [8] ARRAY '(anon)' type_id=7 index_type_id=9 nr_elems=16
167 [9] INT '__ARRAY_SIZE_TYPE__' size=4 bits_of 160 [9] INT '__ARRAY_SIZE_TYPE__' size=4 bits_offset=0 nr_bits=32 encoding=(none)
168 [10] RESTRICT '(anon)' type_id=11 161 [10] RESTRICT '(anon)' type_id=11
169 [11] PTR '(anon)' type_id=12 162 [11] PTR '(anon)' type_id=12
170 [12] CONST '(anon)' type_id=13 163 [12] CONST '(anon)' type_id=13
171 [13] FWD 'fwd_struct' fwd_kind=union 164 [13] FWD 'fwd_struct' fwd_kind=union
172 [14] ENUM 'my_enum' size=4 vlen=2 165 [14] ENUM 'my_enum' size=4 vlen=2
173 'VAL1' val=3 166 'VAL1' val=3
174 'VAL2' val=7 167 'VAL2' val=7
175 [15] PTR '(anon)' type_id=16 168 [15] PTR '(anon)' type_id=16
176 [16] VOLATILE '(anon)' type_id=17 169 [16] VOLATILE '(anon)' type_id=17
177 [17] TYPEDEF 'my_struct_t' type_id=4 170 [17] TYPEDEF 'my_struct_t' type_id=4
178 [18] FUNC_PROTO '(anon)' ret_type_id=3 vlen= 171 [18] FUNC_PROTO '(anon)' ret_type_id=3 vlen=2
179 'arg1' type_id=1 172 'arg1' type_id=1
180 'arg2' type_id=3 173 'arg2' type_id=3
181 [19] FUNC 'my_func' type_id=18 174 [19] FUNC 'my_func' type_id=18
182 [20] VAR 'struct_global_var' type_id=4, link 175 [20] VAR 'struct_global_var' type_id=4, linkage=global-alloc
183 [21] VAR 'global_var' type_id=3, linkage=glo 176 [21] VAR 'global_var' type_id=3, linkage=global-alloc
184 [22] VAR 'my_func.static_var' type_id=3, lin 177 [22] VAR 'my_func.static_var' type_id=3, linkage=static
185 [23] DATASEC 'data_sec' size=0 vlen=3 178 [23] DATASEC 'data_sec' size=0 vlen=3
186 type_id=20 offset=0 size=48 179 type_id=20 offset=0 size=48
187 type_id=21 offset=0 size=4 180 type_id=21 offset=0 size=4
188 type_id=22 offset=52 size=4 181 type_id=22 offset=52 size=4
189 182
190 The following commands print BTF types associa 183 The following commands print BTF types associated with specified map's key,
191 value, both key and value, and all BTF types, 184 value, both key and value, and all BTF types, respectively. By default, both
192 key and value types will be printed. 185 key and value types will be printed.
193 186
194 **# bpftool btf dump map id 123 key** 187 **# bpftool btf dump map id 123 key**
195 188
196 :: 189 ::
197 190
198 [39] TYPEDEF 'u32' type_id=37 191 [39] TYPEDEF 'u32' type_id=37
199 192
200 **# bpftool btf dump map id 123 value** 193 **# bpftool btf dump map id 123 value**
201 194
202 :: 195 ::
203 196
204 [86] PTR '(anon)' type_id=87 197 [86] PTR '(anon)' type_id=87
205 198
206 **# bpftool btf dump map id 123 kv** 199 **# bpftool btf dump map id 123 kv**
207 200
208 :: 201 ::
209 202
210 [39] TYPEDEF 'u32' type_id=37 203 [39] TYPEDEF 'u32' type_id=37
211 [86] PTR '(anon)' type_id=87 204 [86] PTR '(anon)' type_id=87
212 205
213 **# bpftool btf dump map id 123 all** 206 **# bpftool btf dump map id 123 all**
214 207
215 :: 208 ::
216 209
217 [1] PTR '(anon)' type_id=0 210 [1] PTR '(anon)' type_id=0
218 . 211 .
219 . 212 .
220 . 213 .
221 [2866] ARRAY '(anon)' type_id=52 index_type_ 214 [2866] ARRAY '(anon)' type_id=52 index_type_id=51 nr_elems=4
222 215
223 All the standard ways to specify map or progra 216 All the standard ways to specify map or program are supported:
224 217
225 **# bpftool btf dump map id 123** 218 **# bpftool btf dump map id 123**
226 219
227 **# bpftool btf dump map pinned /sys/fs/bpf/ma 220 **# bpftool btf dump map pinned /sys/fs/bpf/map_name**
228 221
229 **# bpftool btf dump prog id 456** 222 **# bpftool btf dump prog id 456**
230 223
231 **# bpftool btf dump prog tag b88e0a09b1d9759d 224 **# bpftool btf dump prog tag b88e0a09b1d9759d**
232 225
233 **# bpftool btf dump prog pinned /sys/fs/bpf/p 226 **# bpftool btf dump prog pinned /sys/fs/bpf/prog_name**
234 227
235 | !! 228 SEE ALSO
236 | **# bpftool btf dump file /sys/kernel/btf/i2 !! 229 ========
237 | (or) !! 230 **bpf**\ (2),
238 | **# I2C_SMBUS_ID=$(bpftool btf show -p | jq !! 231 **bpf-helpers**\ (7),
239 | **# bpftool btf dump id ${I2C_SMBUS_ID} -B / !! 232 **bpftool**\ (8),
240 !! 233 **bpftool-map**\ (8),
241 :: !! 234 **bpftool-prog**\ (8),
242 !! 235 **bpftool-cgroup**\ (8),
243 [104848] STRUCT 'i2c_smbus_alert' size=40 vl !! 236 **bpftool-feature**\ (8),
244 'alert' type_id=393 bits_offset=0 !! 237 **bpftool-net**\ (8),
245 'ara' type_id=56050 bits_offset=256 !! 238 **bpftool-perf**\ (8)
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 <<
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.