9406b485de
Currently, only one command is supported
bpftool iter pin <bpf_prog.o> <path>
It will pin the trace/iter bpf program in
the object file <bpf_prog.o> to the <path>
where <path> should be on a bpffs mount.
For example,
$ bpftool iter pin ./bpf_iter_ipv6_route.o \
/sys/fs/bpf/my_route
User can then do a `cat` to print out the results:
$ cat /sys/fs/bpf/my_route
fe800000000000000000000000000000 40 00000000000000000000000000000000 ...
00000000000000000000000000000000 00 00000000000000000000000000000000 ...
00000000000000000000000000000001 80 00000000000000000000000000000000 ...
fe800000000000008c0162fffebdfd57 80 00000000000000000000000000000000 ...
ff000000000000000000000000000000 08 00000000000000000000000000000000 ...
00000000000000000000000000000000 00 00000000000000000000000000000000 ...
The implementation for ipv6_route iterator is in one of subsequent
patches.
This patch also added BPF_LINK_TYPE_ITER to link query.
In the future, we may add additional parameters to pin command
by parameterizing the bpf iterator. For example, a map_id or pid
may be added to let bpf program only traverses a single map or task,
similar to kernel seq_file single_open().
We may also add introspection command for targets/iterators by
leveraging the bpf_iter itself.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200509175920.2477247-1-yhs@fb.com
84 lines
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84 lines
2.0 KiB
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============
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bpftool-iter
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============
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-------------------------------------------------------------------------------
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tool to create BPF iterators
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-------------------------------------------------------------------------------
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:Manual section: 8
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SYNOPSIS
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========
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**bpftool** [*OPTIONS*] **iter** *COMMAND*
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*COMMANDS* := { **pin** | **help** }
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ITER COMMANDS
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===================
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| **bpftool** **iter pin** *OBJ* *PATH*
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| **bpftool** **iter help**
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| *OBJ* := /a/file/of/bpf_iter_target.o
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DESCRIPTION
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===========
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**bpftool iter pin** *OBJ* *PATH*
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A bpf iterator combines a kernel iterating of
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particular kernel data (e.g., tasks, bpf_maps, etc.)
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and a bpf program called for each kernel data object
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(e.g., one task, one bpf_map, etc.). User space can
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*read* kernel iterator output through *read()* syscall.
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The *pin* command creates a bpf iterator from *OBJ*,
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and pin it to *PATH*. The *PATH* should be located
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in *bpffs* mount. It must not contain a dot
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character ('.'), which is reserved for future extensions
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of *bpffs*.
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User can then *cat PATH* to see the bpf iterator output.
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**bpftool iter help**
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Print short help message.
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OPTIONS
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=======
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-h, --help
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Print short generic help message (similar to **bpftool help**).
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-V, --version
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Print version number (similar to **bpftool version**).
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-d, --debug
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Print all logs available, even debug-level information. This
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includes logs from libbpf as well as from the verifier, when
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attempting to load programs.
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EXAMPLES
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========
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**# bpftool iter pin bpf_iter_netlink.o /sys/fs/bpf/my_netlink**
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::
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Create a file-based bpf iterator from bpf_iter_netlink.o and pin it
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to /sys/fs/bpf/my_netlink
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SEE ALSO
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========
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**bpf**\ (2),
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**bpf-helpers**\ (7),
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**bpftool**\ (8),
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**bpftool-prog**\ (8),
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**bpftool-map**\ (8),
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**bpftool-link**\ (8),
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**bpftool-cgroup**\ (8),
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**bpftool-feature**\ (8),
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**bpftool-net**\ (8),
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**bpftool-perf**\ (8),
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**bpftool-btf**\ (8)
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**bpftool-gen**\ (8)
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**bpftool-struct_ops**\ (8)
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