Linux Manpages Online - man.cx manual pages

NAME

bpftool-prog - tool for inspection and simple manipulation of eBPF progs

SYNOPSIS

bpftool [OPTIONS] prog COMMAND

OPTIONS := { { -j | --json } [{ -p | --pretty }] | { -d | --debug } | { -f | --bpffs } | { -m | --mapcompat } | { -n | --nomount } | { -L | --use-loader } }

COMMANDS := { show | list | dump xlated | dump jited | pin | load | loadall | help }

bpftool prog { show | list } [PROG]
bpftool prog dump xlated PROG [{ file FILE | [opcodes] [linum] [visual] }]
bpftool prog dump jited PROG [{ file FILE | [opcodes] [linum] }]
bpftool prog pin PROG FILE
bpftool prog { load | loadall } OBJ PATH [type TYPE] [map { idx IDX | name NAME } MAP] [{ offload_dev | xdpmeta_dev } NAME] [pinmaps MAP_DIR] [autoattach]
bpftool prog attach PROG ATTACH_TYPE [MAP]
bpftool prog detach PROG ATTACH_TYPE [MAP]
bpftool prog tracelog
bpftool prog run PROG data_in FILE [data_out FILE [data_size_out L]] [ctx_in FILE [ctx_out FILE [ctx_size_out M]]] [repeat N]
bpftool prog profile PROG [duration DURATION] METRICs
bpftool prog help

MAP := { id MAP_ID | pinned FILE }
PROG := { id PROG_ID | pinned FILE | tag PROG_TAG | name PROG_NAME }
TYPE := {

}
ATTACH_TYPE := {

sk_msg_verdict | sk_skb_verdict | sk_skb_stream_verdict |
sk_skb_stream_parser | flow_dissector

}
METRICs := {

}

DESCRIPTION

bpftool prog { show | list } [PROG]

Show information about loaded programs. If PROG is specified show information only about given programs, otherwise list all programs currently loaded on the system. In case of tag or name, PROG may match several programs which will all be shown.

Output will start with program ID followed by program type and zero or more named attributes (depending on kernel version).

Since Linux 5.1 the kernel can collect statistics on BPF programs (such as the total time spent running the program, and the number of times it was run). If available, bpftool shows such statistics. However, the kernel does not collect them by defaults, as it slightly impacts performance on each program run. Activation or deactivation of the feature is performed via the kernel.bpf_stats_enabled sysctl knob.

Since Linux 5.8 bpftool is able to discover information about processes that hold open file descriptors (FDs) against BPF programs. On such kernels bpftool will automatically emit this information as well.

bpftool prog dump xlated PROG [{ file FILE | [opcodes] [linum]
[visual] }]

Dump eBPF instructions of the programs from the kernel. By default, eBPF will be disassembled and printed to standard output in human-readable format. In this case, opcodes controls if raw opcodes should be printed as well.

In case of tag or name, PROG may match several programs which will all be dumped. However, if file or visual is specified, PROG must match a single program.

If file is specified, the binary image will instead be written to FILE.

If visual is specified, control flow graph (CFG) will be built instead, and eBPF instructions will be presented with CFG in DOT format, on standard output.

If the programs have line_info available, the source line will be displayed. If linum is specified, the filename, line number and line column will also be displayed.

bpftool prog dump jited PROG [{ file FILE | [opcodes] [linum] }]

Dump jited image (host machine code) of the program.

If FILE is specified image will be written to a file, otherwise it will be disassembled and printed to stdout. PROG must match a single program when file is specified.

opcodes controls if raw opcodes will be printed.

If the prog has line_info available, the source line will be displayed. If linum is specified, the filename, line number and line column will also be displayed.

bpftool prog pin PROG FILE

Pin program PROG as FILE.

Note: FILE must be located in bpffs mount. It must not contain a dot character ('.'), which is reserved for future extensions of bpffs.

bpftool prog { load | loadall } OBJ PATH [type TYPE] [map { idx IDX
| name NAME } MAP] [{ offload_dev | xdpmeta_dev } NAME] [pinmaps
MAP_DIR] [autoattach]

Load bpf program(s) from binary OBJ and pin as PATH. bpftool prog load pins only the first program from the OBJ as PATH. bpftool prog loadall pins all programs from the OBJ under PATH directory. type is optional, if not specified program type will be inferred from section names. By default bpftool will create new maps as declared in the ELF object being loaded. map parameter allows for the reuse of existing maps. It can be specified multiple times, each time for a different map. IDX refers to index of the map to be replaced in the ELF file counting from 0, while NAME allows to replace a map by name. MAP specifies the map to use, referring to it by id or through a pinned file. If offload_dev NAME is specified program will be loaded onto given networking device (offload). If xdpmeta_dev NAME is specified program will become device-bound without offloading, this facilitates access to XDP metadata. Optional pinmaps argument can be provided to pin all maps under MAP_DIR directory.

If autoattach is specified program will be attached before pin. In that case, only the link (representing the program attached to its hook) is pinned, not the program as such, so the path won't show in bpftool prog show -f, only show in bpftool link show -f. Also, this only works when bpftool (libbpf) is able to infer all necessary information from the object file, in particular, it's not supported for all program types. If a program does not support autoattach, bpftool falls back to regular pinning for that program instead.

Note: PATH must be located in bpffs mount. It must not contain a dot character ('.'), which is reserved for future extensions of bpffs.

bpftool prog attach PROG ATTACH_TYPE [MAP]

Attach bpf program PROG (with type specified by ATTACH_TYPE). Most ATTACH_TYPEs require a MAP parameter, with the exception of flow_dissector which is attached to current networking name space.

bpftool prog detach PROG ATTACH_TYPE [MAP]

Detach bpf program PROG (with type specified by ATTACH_TYPE). Most ATTACH_TYPEs require a MAP parameter, with the exception of flow_dissector which is detached from the current networking name space.

bpftool prog tracelog

Dump the trace pipe of the system to the console (stdout). Hit <Ctrl+C> to stop printing. BPF programs can write to this trace pipe at runtime with the bpf_trace_printk() helper. This should be used only for debugging purposes. For streaming data from BPF programs to user space, one can use perf events (see also bpftool-map(8)).

bpftool prog run PROG data_in FILE [data_out FILE [data_size_out L]]
[ctx_in FILE [ctx_out FILE [ctx_size_out M]]] [repeat N]

Run BPF program PROG in the kernel testing infrastructure for BPF, meaning that the program works on the data and context provided by the user, and not on actual packets or monitored functions etc. Return value and duration for the test run are printed out to the console.

Input data is read from the FILE passed with data_in. If this FILE is "-", input data is read from standard input. Input context, if any, is read from FILE passed with ctx_in. Again, "-" can be used to read from standard input, but only if standard input is not already in use for input data. If a FILE is passed with data_out, output data is written to that file. Similarly, output context is written to the FILE passed with ctx_out. For both output flows, "-" can be used to print to the standard output (as plain text, or JSON if relevant option was passed). If output keywords are omitted, output data and context are discarded. Keywords data_size_out and ctx_size_out are used to pass the size (in bytes) for the output buffers to the kernel, although the default of 32 kB should be more than enough for most cases.

Keyword repeat is used to indicate the number of consecutive runs to perform. Note that output data and context printed to files correspond to the last of those runs. The duration printed out at the end of the runs is an average over all runs performed by the command.

Not all program types support test run. Among those which do, not all of them can take the ctx_in/ctx_out arguments. bpftool does not perform checks on program types.

bpftool prog profile PROG [duration DURATION] METRICs

Profile METRICs for bpf program PROG for DURATION seconds or until user hits <Ctrl+C>. DURATION is optional. If DURATION is not specified, the profiling will run up to UINT_MAX seconds.

bpftool prog help

Print short help message.

OPTIONS

-h, --help

Print short help message (similar to bpftool help).

-V, --version

Print bpftool's version number (similar to bpftool version), the number of the libbpf version in use, and optional features that were included when bpftool was compiled. Optional features include linking against LLVM or libbfd to provide the disassembler for JIT-ted programs (bpftool prog dump jited) and usage of BPF skeletons (some features like bpftool prog profile or showing pids associated to BPF objects may rely on it).

-j, --json

Generate JSON output. For commands that cannot produce JSON, this option has no effect.

-p, --pretty

Generate human-readable JSON output. Implies -j.

-d, --debug

Print all logs available, even debug-level information. This includes logs from libbpf as well as from the verifier, when attempting to load programs.

-f, --bpffs

When showing BPF programs, show file names of pinned programs.

-m, --mapcompat

Allow loading maps with unknown map definitions.

-n, --nomount

Do not automatically attempt to mount any virtual file system (such as tracefs or BPF virtual file system) when necessary.

-L, --use-loader

Load program as a "loader" program. This is useful to debug the generation of such programs. When this option is in use, bpftool attempts to load the programs from the object file into the kernel, but does not pin them (therefore, the PATH must not be provided).

When combined with the -d|--debug option, additional debug messages are generated, and the execution of the loader program will use the bpf_trace_printk() helper to log each step of loading BTF, creating the maps, and loading the programs (see bpftool prog tracelog as a way to dump those messages).

EXAMPLES

# bpftool prog show

10: xdp name some_prog tag 005a3d2123620c8b gpl run_time_ns 81632 run_cnt 10
loaded_at 2017-09-29T20:11:00+0000 uid 0
xlated 528B jited 370B memlock 4096B map_ids 10
pids systemd(1)

# bpftool --json --pretty prog show

[{
"id": 10,
"type": "xdp",
"tag": "005a3d2123620c8b",
"gpl_compatible": true,
"run_time_ns": 81632,
"run_cnt": 10,
"loaded_at": 1506715860,
"uid": 0,
"bytes_xlated": 528,
"jited": true,
"bytes_jited": 370,
"bytes_memlock": 4096,
"map_ids": [10
],
"pids": [{
"pid": 1,
"comm": "systemd"
}
]
}
]

# bpftool prog dump xlated id 10 file /tmp/t
$ ls -l /tmp/t

-rw------- 1 root root 560 Jul 22 01:42 /tmp/t

# bpftool prog dump jited tag 005a3d2123620c8b

0: push %rbp
1: mov %rsp,%rbp
2: sub $0x228,%rsp
3: sub $0x28,%rbp
4: mov %rbx,0x0(%rbp)

# mount -t bpf none /sys/fs/bpf/
# bpftool prog pin id 10 /sys/fs/bpf/prog
# bpftool prog load ./my_prog.o /sys/fs/bpf/prog2
# ls -l /sys/fs/bpf/

-rw------- 1 root root 0 Jul 22 01:43 prog
-rw------- 1 root root 0 Jul 22 01:44 prog2

# bpftool prog dump jited pinned /sys/fs/bpf/prog opcodes

0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x228,%rsp
48 81 ec 28 02 00 00
b: sub $0x28,%rbp
48 83 ed 28
f: mov %rbx,0x0(%rbp)
48 89 5d 00

# bpftool prog load xdp1_kern.o /sys/fs/bpf/xdp1 type xdp map name rxcnt id 7
# bpftool prog show pinned /sys/fs/bpf/xdp1

9: xdp name xdp_prog1 tag 539ec6ce11b52f98 gpl
loaded_at 2018-06-25T16:17:31-0700 uid 0
xlated 488B jited 336B memlock 4096B map_ids 7

# rm /sys/fs/bpf/xdp1

# bpftool prog profile id 337 duration 10 cycles instructions llc_misses

51397 run_cnt
40176203 cycles (83.05%)
42518139 instructions # 1.06 insns per cycle (83.39%)
123 llc_misses # 2.89 LLC misses per million insns (83.15%)

Output below is for the trace logs.
Run in separate terminals:
# bpftool prog tracelog
# bpftool prog load -L -d file.o

bpftool-620059 [004] d... 2634685.517903: bpf_trace_printk: btf_load size 665 r=5
bpftool-620059 [004] d... 2634685.517912: bpf_trace_printk: map_create sample_map idx 0 type 2 value_size 4 value_btf_id 0 r=6
bpftool-620059 [004] d... 2634685.517997: bpf_trace_printk: prog_load sample insn_cnt 13 r=7
bpftool-620059 [004] d... 2634685.517999: bpf_trace_printk: close(5) = 0

Manpages

NAME

SYNOPSIS

PROG COMMANDS

DESCRIPTION

OPTIONS

EXAMPLES

SEE ALSO