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 Since Linux 5.8 bpftool is able to discover information about
44 bpftool will automatically emit this infor !! 40 processes that hold open file descriptors (FDs) against BTF
45 !! 41 objects. On such kernels bpftool will automatically emit this
46 bpftool btf dump *BTF_SRC* !! 42 information as well.
47 Dump BTF entries from a given *BTF_SRC*. !! 43
48 !! 44 **bpftool btf dump** *BTF_SRC*
49 When **id** is specified, BTF object with !! 45 Dump BTF entries from a given *BTF_SRC*.
50 its BTF types emitted. !! 46
51 !! 47 When **id** is specified, BTF object with that ID will be
52 When **map** is provided, it's expected th !! 48 loaded and all its BTF types emitted.
53 with BTF types describing key and value. I !! 49
54 dump only BTF type(s) associated with key !! 50 When **map** is provided, it's expected that map has
55 both key and value (**kv**), or all BTF ty !! 51 associated BTF object with BTF types describing key and
56 object (**all**). If not specified, **kv** !! 52 value. It's possible to select whether to dump only BTF
57 !! 53 type(s) associated with key (**key**), value (**value**),
58 When **prog** is provided, it's expected t !! 54 both key and value (**kv**), or all BTF types present in
59 object with BTF types. !! 55 associated BTF object (**all**). If not specified, **kv**
60 !! 56 is assumed.
61 When specifying *FILE*, an ELF file is exp !! 57
62 with well-defined BTF binary format data, !! 58 When **prog** is provided, it's expected that program has
63 pahole. !! 59 associated BTF object with BTF types.
64 !! 60
65 **format** option can be used to override !! 61 When specifying *FILE*, an ELF file is expected, containing
66 (**raw**) or C-syntax (**c**) output forma !! 62 .BTF section with well-defined BTF binary format data,
67 formatting, the output is sorted by defaul !! 63 typically produced by clang or pahole.
68 to avoid sorting the output. !! 64
>> 65 **format** option can be used to override default (raw)
>> 66 output format. Raw (**raw**) or C-syntax (**c**) output
>> 67 formats are supported.
69 68
70 bpftool btf help !! 69 **bpftool btf help**
71 Print short help message. !! 70 Print short help message.
72 71
73 OPTIONS 72 OPTIONS
74 ======= 73 =======
75 .. include:: common_options.rst !! 74 -h, --help
>> 75 Print short generic help message (similar to **bpftool help**).
>> 76
>> 77 -V, --version
>> 78 Print version number (similar to **bpftool version**).
76 79
77 -B, --base-btf *FILE* !! 80 -j, --json
78 Pass a base BTF object. Base BTF objects a !! 81 Generate JSON output. For commands that cannot produce JSON, this
79 objects for kernel modules. To avoid dupli !! 82 option has no effect.
80 required by modules, BTF objects for modul !! 83
81 built incrementally on top of the kernel ( !! 84 -p, --pretty
82 base BTF reference should usually point to !! 85 Generate human-readable JSON output. Implies **-j**.
83 !! 86
84 When the main BTF object to process (for e !! 87 -d, --debug
85 dump) is passed as a *FILE*, bpftool attem !! 88 Print all logs available from libbpf, including debug-level
86 for the base object, and passing this opti !! 89 information.
87 BTF object is passed through other handles <<
88 necessary. <<
89 90
90 EXAMPLES 91 EXAMPLES
91 ======== 92 ========
92 **# bpftool btf dump id 1226** 93 **# bpftool btf dump id 1226**
93 <<
94 :: 94 ::
95 95
96 [1] PTR '(anon)' type_id=2 96 [1] PTR '(anon)' type_id=2
97 [2] STRUCT 'dummy_tracepoint_args' size=16 v 97 [2] STRUCT 'dummy_tracepoint_args' size=16 vlen=2
98 'pad' type_id=3 bits_offset=0 98 'pad' type_id=3 bits_offset=0
99 'sock' type_id=4 bits_offset=64 99 'sock' type_id=4 bits_offset=64
100 [3] INT 'long long unsigned int' size=8 bits 100 [3] INT 'long long unsigned int' size=8 bits_offset=0 nr_bits=64 encoding=(none)
101 [4] PTR '(anon)' type_id=5 101 [4] PTR '(anon)' type_id=5
102 [5] FWD 'sock' fwd_kind=union 102 [5] FWD 'sock' fwd_kind=union
103 103
104 This gives an example of default output for al 104 This gives an example of default output for all supported BTF kinds.
105 105
106 **$ cat prog.c** 106 **$ cat prog.c**
107 <<
108 :: 107 ::
109 108
110 struct fwd_struct; 109 struct fwd_struct;
111 110
112 enum my_enum { 111 enum my_enum {
113 VAL1 = 3, 112 VAL1 = 3,
114 VAL2 = 7, 113 VAL2 = 7,
115 }; 114 };
116 115
117 typedef struct my_struct my_struct_t; 116 typedef struct my_struct my_struct_t;
118 117
119 struct my_struct { 118 struct my_struct {
120 const unsigned int const_int_field; 119 const unsigned int const_int_field;
121 int bitfield_field: 4; 120 int bitfield_field: 4;
122 char arr_field[16]; 121 char arr_field[16];
123 const struct fwd_struct *restrict fw 122 const struct fwd_struct *restrict fwd_field;
124 enum my_enum enum_field; 123 enum my_enum enum_field;
125 volatile my_struct_t *typedef_ptr_fi 124 volatile my_struct_t *typedef_ptr_field;
126 }; 125 };
127 126
128 union my_union { 127 union my_union {
129 int a; 128 int a;
130 struct my_struct b; 129 struct my_struct b;
131 }; 130 };
132 131
133 struct my_struct struct_global_var __attribu 132 struct my_struct struct_global_var __attribute__((section("data_sec"))) = {
134 .bitfield_field = 3, 133 .bitfield_field = 3,
135 .enum_field = VAL1, 134 .enum_field = VAL1,
136 }; 135 };
137 int global_var __attribute__((section("data_ 136 int global_var __attribute__((section("data_sec"))) = 7;
138 137
139 __attribute__((noinline)) 138 __attribute__((noinline))
140 int my_func(union my_union *arg1, int arg2) 139 int my_func(union my_union *arg1, int arg2)
141 { 140 {
142 static int static_var __attribute__( 141 static int static_var __attribute__((section("data_sec"))) = 123;
143 static_var++; 142 static_var++;
144 return static_var; 143 return static_var;
145 } 144 }
146 145
147 **$ bpftool btf dump file prog.o** 146 **$ bpftool btf dump file prog.o**
148 <<
149 :: 147 ::
150 148
151 [1] PTR '(anon)' type_id=2 149 [1] PTR '(anon)' type_id=2
152 [2] UNION 'my_union' size=48 vlen=2 150 [2] UNION 'my_union' size=48 vlen=2
153 'a' type_id=3 bits_offset=0 151 'a' type_id=3 bits_offset=0
154 'b' type_id=4 bits_offset=0 152 'b' type_id=4 bits_offset=0
155 [3] INT 'int' size=4 bits_offset=0 nr_bits=3 153 [3] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED
156 [4] STRUCT 'my_struct' size=48 vlen=6 154 [4] STRUCT 'my_struct' size=48 vlen=6
157 'const_int_field' type_id=5 bits_off 155 'const_int_field' type_id=5 bits_offset=0
158 'bitfield_field' type_id=3 bits_offs 156 'bitfield_field' type_id=3 bits_offset=32 bitfield_size=4
159 'arr_field' type_id=8 bits_offset=40 157 'arr_field' type_id=8 bits_offset=40
160 'fwd_field' type_id=10 bits_offset=1 158 'fwd_field' type_id=10 bits_offset=192
161 'enum_field' type_id=14 bits_offset= 159 'enum_field' type_id=14 bits_offset=256
162 'typedef_ptr_field' type_id=15 bits_ 160 'typedef_ptr_field' type_id=15 bits_offset=320
163 [5] CONST '(anon)' type_id=6 161 [5] CONST '(anon)' type_id=6
164 [6] INT 'unsigned int' size=4 bits_offset=0 162 [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= 163 [7] INT 'char' size=1 bits_offset=0 nr_bits=8 encoding=SIGNED
166 [8] ARRAY '(anon)' type_id=7 index_type_id=9 164 [8] ARRAY '(anon)' type_id=7 index_type_id=9 nr_elems=16
167 [9] INT '__ARRAY_SIZE_TYPE__' size=4 bits_of 165 [9] INT '__ARRAY_SIZE_TYPE__' size=4 bits_offset=0 nr_bits=32 encoding=(none)
168 [10] RESTRICT '(anon)' type_id=11 166 [10] RESTRICT '(anon)' type_id=11
169 [11] PTR '(anon)' type_id=12 167 [11] PTR '(anon)' type_id=12
170 [12] CONST '(anon)' type_id=13 168 [12] CONST '(anon)' type_id=13
171 [13] FWD 'fwd_struct' fwd_kind=union 169 [13] FWD 'fwd_struct' fwd_kind=union
172 [14] ENUM 'my_enum' size=4 vlen=2 170 [14] ENUM 'my_enum' size=4 vlen=2
173 'VAL1' val=3 171 'VAL1' val=3
174 'VAL2' val=7 172 'VAL2' val=7
175 [15] PTR '(anon)' type_id=16 173 [15] PTR '(anon)' type_id=16
176 [16] VOLATILE '(anon)' type_id=17 174 [16] VOLATILE '(anon)' type_id=17
177 [17] TYPEDEF 'my_struct_t' type_id=4 175 [17] TYPEDEF 'my_struct_t' type_id=4
178 [18] FUNC_PROTO '(anon)' ret_type_id=3 vlen= 176 [18] FUNC_PROTO '(anon)' ret_type_id=3 vlen=2
179 'arg1' type_id=1 177 'arg1' type_id=1
180 'arg2' type_id=3 178 'arg2' type_id=3
181 [19] FUNC 'my_func' type_id=18 179 [19] FUNC 'my_func' type_id=18
182 [20] VAR 'struct_global_var' type_id=4, link 180 [20] VAR 'struct_global_var' type_id=4, linkage=global-alloc
183 [21] VAR 'global_var' type_id=3, linkage=glo 181 [21] VAR 'global_var' type_id=3, linkage=global-alloc
184 [22] VAR 'my_func.static_var' type_id=3, lin 182 [22] VAR 'my_func.static_var' type_id=3, linkage=static
185 [23] DATASEC 'data_sec' size=0 vlen=3 183 [23] DATASEC 'data_sec' size=0 vlen=3
186 type_id=20 offset=0 size=48 184 type_id=20 offset=0 size=48
187 type_id=21 offset=0 size=4 185 type_id=21 offset=0 size=4
188 type_id=22 offset=52 size=4 186 type_id=22 offset=52 size=4
189 187
190 The following commands print BTF types associa 188 The following commands print BTF types associated with specified map's key,
191 value, both key and value, and all BTF types, 189 value, both key and value, and all BTF types, respectively. By default, both
192 key and value types will be printed. 190 key and value types will be printed.
193 191
194 **# bpftool btf dump map id 123 key** 192 **# bpftool btf dump map id 123 key**
195 193
196 :: 194 ::
197 195
198 [39] TYPEDEF 'u32' type_id=37 196 [39] TYPEDEF 'u32' type_id=37
199 197
200 **# bpftool btf dump map id 123 value** 198 **# bpftool btf dump map id 123 value**
201 199
202 :: 200 ::
203 201
204 [86] PTR '(anon)' type_id=87 202 [86] PTR '(anon)' type_id=87
205 203
206 **# bpftool btf dump map id 123 kv** 204 **# bpftool btf dump map id 123 kv**
207 205
208 :: 206 ::
209 207
210 [39] TYPEDEF 'u32' type_id=37 208 [39] TYPEDEF 'u32' type_id=37
211 [86] PTR '(anon)' type_id=87 209 [86] PTR '(anon)' type_id=87
212 210
213 **# bpftool btf dump map id 123 all** 211 **# bpftool btf dump map id 123 all**
214 212
215 :: 213 ::
216 214
217 [1] PTR '(anon)' type_id=0 215 [1] PTR '(anon)' type_id=0
218 . 216 .
219 . 217 .
220 . 218 .
221 [2866] ARRAY '(anon)' type_id=52 index_type_ 219 [2866] ARRAY '(anon)' type_id=52 index_type_id=51 nr_elems=4
222 220
223 All the standard ways to specify map or progra 221 All the standard ways to specify map or program are supported:
224 222
225 **# bpftool btf dump map id 123** 223 **# bpftool btf dump map id 123**
226 224
227 **# bpftool btf dump map pinned /sys/fs/bpf/ma 225 **# bpftool btf dump map pinned /sys/fs/bpf/map_name**
228 226
229 **# bpftool btf dump prog id 456** 227 **# bpftool btf dump prog id 456**
230 228
231 **# bpftool btf dump prog tag b88e0a09b1d9759d 229 **# bpftool btf dump prog tag b88e0a09b1d9759d**
232 230
233 **# bpftool btf dump prog pinned /sys/fs/bpf/p 231 **# bpftool btf dump prog pinned /sys/fs/bpf/prog_name**
234 232
235 | !! 233 SEE ALSO
236 | **# bpftool btf dump file /sys/kernel/btf/i2 !! 234 ========
237 | (or) !! 235 **bpf**\ (2),
238 | **# I2C_SMBUS_ID=$(bpftool btf show -p | jq !! 236 **bpf-helpers**\ (7),
239 | **# bpftool btf dump id ${I2C_SMBUS_ID} -B / !! 237 **bpftool**\ (8),
240 !! 238 **bpftool-btf**\ (8),
241 :: !! 239 **bpftool-cgroup**\ (8),
242 !! 240 **bpftool-feature**\ (8),
243 [104848] STRUCT 'i2c_smbus_alert' size=40 vl !! 241 **bpftool-gen**\ (8),
244 'alert' type_id=393 bits_offset=0 !! 242 **bpftool-iter**\ (8),
245 'ara' type_id=56050 bits_offset=256 !! 243 **bpftool-link**\ (8),
246 [104849] STRUCT 'alert_data' size=12 vlen=3 !! 244 **bpftool-map**\ (8),
247 'addr' type_id=16 bits_offset=0 !! 245 **bpftool-net**\ (8),
248 'type' type_id=56053 bits_offset=32 !! 246 **bpftool-perf**\ (8),
249 'data' type_id=7 bits_offset=64 !! 247 **bpftool-prog**\ (8),
250 [104850] PTR '(anon)' type_id=104848 !! 248 **bpftool-struct_ops**\ (8)
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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