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Diffstat (limited to 'tools/bpf/bpftool/Documentation/bpftool-btf.rst')
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1 files changed, 92 insertions, 66 deletions
diff --git a/tools/bpf/bpftool/Documentation/bpftool-btf.rst b/tools/bpf/bpftool/Documentation/bpftool-btf.rst index ce3a724f50c1..d47dddc2b4ee 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-btf.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-btf.rst @@ -1,3 +1,5 @@ +.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) + ================ bpftool-btf ================ @@ -7,85 +9,93 @@ tool for inspection of BTF data :Manual section: 8 +.. include:: substitutions.rst + SYNOPSIS ======== - **bpftool** [*OPTIONS*] **btf** *COMMAND* +**bpftool** [*OPTIONS*] **btf** *COMMAND* - *OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] } +*OPTIONS* := { |COMMON_OPTIONS| | { **-B** | **--base-btf** } } - *COMMANDS* := { **dump** | **help** } +*COMMANDS* := { **dump** | **help** } BTF COMMANDS ============= -| **bpftool** **btf** { **show** | **list** } [**id** *BTF_ID*] -| **bpftool** **btf dump** *BTF_SRC* [**format** *FORMAT*] -| **bpftool** **btf help** +| **bpftool** **btf** { **show** | **list** } [**id** *BTF_ID*] +| **bpftool** **btf dump** *BTF_SRC* [**format** *FORMAT*] [**root_id** *ROOT_ID*] +| **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* } +| *BTF_SRC* := { **id** *BTF_ID* | **prog** *PROG* | **map** *MAP* [{**key** | **value** | **kv** | **all**}] | **file** *FILE* } +| *FORMAT* := { **raw** | **c** [**unsorted**] } +| *MAP* := { **id** *MAP_ID* | **pinned** *FILE* } +| *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* | **name** *PROG_NAME* } 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 { 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*. + Since Linux 5.8 bpftool is able to discover information about processes + that hold open file descriptors (FDs) against BTF objects. On such kernels + bpftool will automatically emit this information as well. - When **id** is specified, BTF object with that ID will be - loaded and all its BTF types emitted. +bpftool btf dump *BTF_SRC* [format *FORMAT*] [root_id *ROOT_ID*] + Dump BTF entries from a given *BTF_SRC*. - 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 **id** is specified, BTF object with that ID will be loaded and all + its BTF types emitted. - When **prog** is provided, it's expected that program has - associated BTF object with BTF types. + 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 specifying *FILE*, an ELF file is expected, containing - .BTF section with well-defined BTF binary format data, - typically produced by clang or pahole. + When **prog** is provided, it's expected that program has associated BTF + object with BTF types. - **format** option can be used to override default (raw) - output format. Raw (**raw**) or C-syntax (**c**) output - formats are supported. + When specifying *FILE*, an ELF file is expected, containing .BTF section + with well-defined BTF binary format data, typically produced by clang or + pahole. - **bpftool btf help** - Print short help message. + **format** option can be used to override default (raw) output format. Raw + (**raw**) or C-syntax (**c**) output formats are supported. With C-style + formatting, the output is sorted by default. Use the **unsorted** option + to avoid sorting the output. -OPTIONS -======= - -h, --help - Print short generic help message (similar to **bpftool help**). + **root_id** option can be used to filter a dump to a single type and all + its dependent types. It cannot be used with any other types of filtering + (such as the "key", "value", or "kv" arguments when dumping BTF for a map). + It can be passed multiple times to dump multiple types. - -V, --version - Print version number (similar to **bpftool version**). +bpftool btf help + Print short help message. - -j, --json - Generate JSON output. For commands that cannot produce JSON, this - option has no effect. +OPTIONS +======= +.. include:: common_options.rst - -p, --pretty - Generate human-readable JSON output. Implies **-j**. +-B, --base-btf *FILE* + Pass a base BTF object. Base BTF objects are typically used with BTF + objects for kernel modules. To avoid duplicating all kernel symbols + required by modules, BTF objects for modules are "split", they are + built incrementally on top of the kernel (vmlinux) BTF object. So the + base BTF reference should usually point to the kernel BTF. - -d, --debug - Print all logs available from libbpf, including debug-level - information. + When the main BTF object to process (for example, the module BTF to + dump) is passed as a *FILE*, bpftool attempts to autodetect the path + for the base object, and passing this option is optional. When the main + BTF object is passed through other handles, this option becomes + necessary. EXAMPLES ======== **# bpftool btf dump id 1226** + :: [1] PTR '(anon)' type_id=2 @@ -99,6 +109,7 @@ EXAMPLES This gives an example of default output for all supported BTF kinds. **$ cat prog.c** + :: struct fwd_struct; @@ -139,6 +150,7 @@ This gives an example of default output for all supported BTF kinds. } **$ bpftool btf dump file prog.o** + :: [1] PTR '(anon)' type_id=2 @@ -225,19 +237,33 @@ All the standard ways to specify map or program are supported: **# 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) +| +| **# bpftool btf dump file /sys/kernel/btf/i2c_smbus** +| (or) +| **# I2C_SMBUS_ID=$(bpftool btf show -p | jq '.[] | select(.name=="i2c_smbus").id')** +| **# bpftool btf dump id ${I2C_SMBUS_ID} -B /sys/kernel/btf/vmlinux** + +:: + + [104848] STRUCT 'i2c_smbus_alert' size=40 vlen=2 + 'alert' type_id=393 bits_offset=0 + 'ara' type_id=56050 bits_offset=256 + [104849] STRUCT 'alert_data' size=12 vlen=3 + 'addr' type_id=16 bits_offset=0 + 'type' type_id=56053 bits_offset=32 + 'data' type_id=7 bits_offset=64 + [104850] PTR '(anon)' type_id=104848 + [104851] PTR '(anon)' type_id=104849 + [104852] FUNC 'i2c_register_spd' type_id=84745 linkage=static + [104853] FUNC 'smbalert_driver_init' type_id=1213 linkage=static + [104854] FUNC_PROTO '(anon)' ret_type_id=18 vlen=1 + 'ara' type_id=56050 + [104855] FUNC 'i2c_handle_smbus_alert' type_id=104854 linkage=static + [104856] FUNC 'smbalert_remove' type_id=104854 linkage=static + [104857] FUNC_PROTO '(anon)' ret_type_id=18 vlen=2 + 'ara' type_id=56050 + 'id' type_id=56056 + [104858] FUNC 'smbalert_probe' type_id=104857 linkage=static + [104859] FUNC 'smbalert_work' type_id=9695 linkage=static + [104860] FUNC 'smbus_alert' type_id=71367 linkage=static + [104861] FUNC 'smbus_do_alert' type_id=84827 linkage=static |