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