BPFTOOL-ITER(8) System Manager's Manual BPFTOOL-ITER(8)
NAME
bpftool-iter - tool to create BPF iterators
SYNOPSIS
bpftool [OPTIONS] iter COMMAND
OPTIONS := { { -j | --json } [{ -p | --pretty }] | { -d | --debug }
}
COMMANDS := { pin | help }
ITER COMMANDS
bpftool iter pin OBJ PATH [map MAP]
bpftool iter help
OBJ := /a/file/of/bpf_iter_target.o
MAP := { id MAP_ID | pinned FILE }
DESCRIPTION
bpftool iter pin OBJ PATH [map MAP]
A bpf iterator combines a kernel iterating of particular ker-
nel data (e.g., tasks, bpf_maps, etc.) and a bpf program
called for each kernel data object (e.g., one task, one
bpf_map, etc.). User space can read kernel iterator output
through read() syscall.
The pin command creates a bpf iterator from OBJ, and pin it
to PATH. The PATH should be located in bpffs mount. It must
not contain a dot character ('.'), which is reserved for fu-
ture extensions of bpffs.
Map element bpf iterator requires an additional parameter MAP
so bpf program can iterate over map elements for that map.
User can have a bpf program in kernel to run with each map
element, do checking, filtering, aggregation, etc. without
copying data to user space.
User can then cat PATH to see the bpf iterator output.
bpftool iter 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 fea-
tures 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.
EXAMPLES
# bpftool iter pin bpf_iter_netlink.o /sys/fs/bpf/my_netlink
Create a file-based bpf iterator from bpf_iter_netlink.o and pin it
to /sys/fs/bpf/my_netlink
# bpftool iter pin bpf_iter_hashmap.o /sys/fs/bpf/my_hashmap map id 20
Create a file-based bpf iterator from bpf_iter_hashmap.o and map with
id 20, and pin it to /sys/fs/bpf/my_hashmap
SEE ALSO
bpf(2), bpf-helpers(7), bpftool(8), bpftool-btf(8),
bpftool-cgroup(8), bpftool-feature(8), bpftool-gen(8),
bpftool-link(8), bpftool-map(8), bpftool-net(8), bpftool-perf(8),
bpftool-prog(8), bpftool-struct_ops(8)
BPFTOOL-ITER(8)
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