History log of /linux-master/tools/bpf/bpftool/link.c
Revision Date Author Comments
# b0dc0373 18-Jan-2024 Jiri Olsa <jolsa@kernel.org>

bpftool: Display cookie for kprobe multi link

Displaying cookies for kprobe multi link, in plain mode:

# bpftool link
...
1397: kprobe_multi prog 47532
kretprobe.multi func_cnt 3
addr cookie func [module]
ffffffff82b370c0 3 bpf_fentry_test1
ffffffff82b39780 1 bpf_fentry_test2
ffffffff82b397a0 2 bpf_fentry_test3

And in json mode:

# bpftool link -j | jq
...
{
"id": 1397,
"type": "kprobe_multi",
"prog_id": 47532,
"retprobe": true,
"func_cnt": 3,
"missed": 0,
"funcs": [
{
"addr": 18446744071607382208,
"func": "bpf_fentry_test1",
"module": null,
"cookie": 3
},
{
"addr": 18446744071607392128,
"func": "bpf_fentry_test2",
"module": null,
"cookie": 1
},
{
"addr": 18446744071607392160,
"func": "bpf_fentry_test3",
"module": null,
"cookie": 2
}
]
}

Cookie is attached to specific address, and because we sort addresses
before printing, we need to sort cookies the same way, hence adding
the struct addr_cookie to keep and sort them together.

Also adding missing dd.sym_count check to show_kprobe_multi_json.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240119110505.400573-9-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>


# 54258324 18-Jan-2024 Jiri Olsa <jolsa@kernel.org>

bpftool: Display cookie for perf event link probes

Displaying cookie for perf event link probes, in plain mode:

# bpftool link
17: perf_event prog 90
kprobe ffffffff82b1c2b0 bpf_fentry_test1 cookie 3735928559
18: perf_event prog 90
kretprobe ffffffff82b1c2b0 bpf_fentry_test1 cookie 3735928559
20: perf_event prog 92
tracepoint sched_switch cookie 3735928559
21: perf_event prog 93
event software:page-faults cookie 3735928559
22: perf_event prog 91
uprobe /proc/self/exe+0xd703c cookie 3735928559

And in json mode:

# bpftool link -j | jq

{
"id": 30,
"type": "perf_event",
"prog_id": 160,
"retprobe": false,
"addr": 18446744071607272112,
"func": "bpf_fentry_test1",
"offset": 0,
"missed": 0,
"cookie": 3735928559
}

{
"id": 33,
"type": "perf_event",
"prog_id": 162,
"tracepoint": "sched_switch",
"cookie": 3735928559
}

{
"id": 34,
"type": "perf_event",
"prog_id": 163,
"event_type": "software",
"event_config": "page-faults",
"cookie": 3735928559
}

{
"id": 35,
"type": "perf_event",
"prog_id": 161,
"retprobe": false,
"file": "/proc/self/exe",
"offset": 880700,
"cookie": 3735928559
}

Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240119110505.400573-8-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>


# 2adb2e0f 18-Jan-2024 Jiri Olsa <jolsa@kernel.org>

bpftool: Fix wrong free call in do_show_link

The error path frees wrong array, it should be ref_ctr_offsets.

Acked-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Fixes: a7795698f8b6 ("bpftool: Add support to display uprobe_multi links")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240119110505.400573-4-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>


# a7795698 25-Nov-2023 Jiri Olsa <jolsa@kernel.org>

bpftool: Add support to display uprobe_multi links

Adding support to display details for uprobe_multi links,
both plain:

# bpftool link -p
...
24: uprobe_multi prog 126
uprobe.multi path /home/jolsa/bpf/test_progs func_cnt 3 pid 4143
offset ref_ctr_offset cookies
0xd1f88 0xf5d5a8 0xdead
0xd1f8f 0xf5d5aa 0xbeef
0xd1f96 0xf5d5ac 0xcafe

and json:

# bpftool link -p
[{
...
},{
"id": 24,
"type": "uprobe_multi",
"prog_id": 126,
"retprobe": false,
"path": "/home/jolsa/bpf/test_progs",
"func_cnt": 3,
"pid": 4143,
"funcs": [{
"offset": 860040,
"ref_ctr_offset": 16111016,
"cookie": 57005
},{
"offset": 860047,
"ref_ctr_offset": 16111018,
"cookie": 48879
},{
"offset": 860054,
"ref_ctr_offset": 16111020,
"cookie": 51966
}
]
}
]

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/bpf/20231125193130.834322-7-jolsa@kernel.org


# 92a85e18 24-Oct-2023 Daniel Borkmann <daniel@iogearbox.net>

bpftool: Implement link show support for netkit

Add support to dump netkit link information to bpftool in similar way as
we have for XDP. The netkit link info only exposes the ifindex and the
attach_type.

Below shows an example link dump output, and a cgroup link is included for
comparison, too:

# bpftool link
[...]
10: cgroup prog 2466
cgroup_id 1 attach_type cgroup_inet6_post_bind
[...]
8: netkit prog 35
ifindex nk1(18) attach_type netkit_primary
[...]

Equivalent json output:

# bpftool link --json
[...]
{
"id": 10,
"type": "cgroup",
"prog_id": 2466,
"cgroup_id": 1,
"attach_type": "cgroup_inet6_post_bind"
},
[...]
{
"id": 12,
"type": "netkit",
"prog_id": 61,
"devname": "nk1",
"ifindex": 21,
"attach_type": "netkit_primary"
}
[...]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20231024214904.29825-5-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>


# b563b9ba 20-Sep-2023 Jiri Olsa <jolsa@kernel.org>

bpftool: Display missed count for kprobe perf link

Adding 'missed' field to display missed counts for kprobes
attached by perf event link, like:

# bpftool link
5: perf_event prog 82
kprobe ffffffff815203e0 ksys_write
6: perf_event prog 83
kprobe ffffffff811d1e50 scheduler_tick missed 682217

# bpftool link -jp
[{
"id": 5,
"type": "perf_event",
"prog_id": 82,
"retprobe": false,
"addr": 18446744071584220128,
"func": "ksys_write",
"offset": 0,
"missed": 0
},{
"id": 6,
"type": "perf_event",
"prog_id": 83,
"retprobe": false,
"addr": 18446744071580753488,
"func": "scheduler_tick",
"offset": 0,
"missed": 693469
}
]

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20230920213145.1941596-7-jolsa@kernel.org


# b24fc355 20-Sep-2023 Jiri Olsa <jolsa@kernel.org>

bpftool: Display missed count for kprobe_multi link

Adding 'missed' field to display missed counts for kprobes
attached by kprobe multi link, like:

# bpftool link
5: kprobe_multi prog 76
kprobe.multi func_cnt 1 missed 1
addr func [module]
ffffffffa039c030 fp3_test [fprobe_test]

# bpftool link -jp
[{
"id": 5,
"type": "kprobe_multi",
"prog_id": 76,
"retprobe": false,
"func_cnt": 1,
"missed": 1,
"funcs": [{
"addr": 18446744072102723632,
"func": "fp3_test",
"module": "fprobe_test"
}
]
}
]

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20230920213145.1941596-6-jolsa@kernel.org


# 6a8faf10 29-Aug-2023 Yafang Shao <laoar.shao@gmail.com>

bpftool: Fix build warnings with -Wtype-limits

Quentin reported build warnings when building bpftool :

link.c: In function ‘perf_config_hw_cache_str’:
link.c:86:18: warning: comparison of unsigned expression in ‘>= 0’ is always true [-Wtype-limits]
86 | if ((id) >= 0 && (id) < ARRAY_SIZE(array)) \
| ^~
link.c:320:20: note: in expansion of macro ‘perf_event_name’
320 | hw_cache = perf_event_name(evsel__hw_cache, config & 0xff);
| ^~~~~~~~~~~~~~~
[... more of the same for the other calls to perf_event_name ...]

He also pointed out the reason and the solution:

We're always passing unsigned, so it should be safe to drop the check on
(id) >= 0.

Fixes: 62b57e3ddd64 ("bpftool: Add perf event names")
Reported-by: Quentin Monnet <quentin@isovalent.com>
Suggested-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Closes: https://lore.kernel.org/bpf/a35d9a2d-54a0-49ec-9ed1-8fcf1369d3cc@isovalent.com
Link: https://lore.kernel.org/bpf/20230830030325.3786-1-laoar.shao@gmail.com


# 053bbf9b 16-Aug-2023 Daniel Borkmann <daniel@iogearbox.net>

bpftool: Implement link show support for xdp

Add support to dump XDP link information to bpftool. This reuses the
recently added show_link_ifindex_{plain,json}(). The XDP link info only
exposes the ifindex.

Below shows an example link dump output, and a cgroup link is included
for comparison, too:

# bpftool link
[...]
10: cgroup prog 2466
cgroup_id 1 attach_type cgroup_inet6_post_bind
[...]
16: xdp prog 2477
ifindex enp5s0(3)
[...]

Equivalent json output:

# bpftool link --json
[...]
{
"id": 10,
"type": "cgroup",
"prog_id": 2466,
"cgroup_id": 1,
"attach_type": "cgroup_inet6_post_bind"
},
[...]
{
"id": 16,
"type": "xdp",
"prog_id": 2477,
"devname": "enp5s0",
"ifindex": 3
}
[...]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/r/20230816095651.10014-2-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>


# e16e6c6d 16-Aug-2023 Daniel Borkmann <daniel@iogearbox.net>

bpftool: Implement link show support for tcx

Add support to dump tcx link information to bpftool. This adds a
common helper show_link_ifindex_{plain,json}() which can be reused
also for other link types. The plain text and json device output is
the same format as in bpftool net dump.

Below shows an example link dump output along with a cgroup link
for comparison:

# bpftool link
[...]
10: cgroup prog 1977
cgroup_id 1 attach_type cgroup_inet6_post_bind
[...]
13: tcx prog 2053
ifindex enp5s0(3) attach_type tcx_ingress
14: tcx prog 2080
ifindex enp5s0(3) attach_type tcx_egress
[...]

Equivalent json output:

# bpftool link --json
[...]
{
"id": 10,
"type": "cgroup",
"prog_id": 1977,
"cgroup_id": 1,
"attach_type": "cgroup_inet6_post_bind"
},
[...]
{
"id": 13,
"type": "tcx",
"prog_id": 2053,
"devname": "enp5s0",
"ifindex": 3,
"attach_type": "tcx_ingress"
},
{
"id": 14,
"type": "tcx",
"prog_id": 2080,
"devname": "enp5s0",
"ifindex": 3,
"attach_type": "tcx_egress"
}
[...]

Suggested-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230816095651.10014-1-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>


# 88d61607 08-Jul-2023 Yafang Shao <laoar.shao@gmail.com>

bpftool: Show perf link info

Enhance bpftool to display comprehensive information about exposed
perf_event links, covering uprobe, kprobe, tracepoint, and generic perf
event. The resulting output will include the following details:

$ tools/bpf/bpftool/bpftool link show
3: perf_event prog 14
event software:cpu-clock
bpf_cookie 0
pids perf_event(19483)
4: perf_event prog 14
event hw-cache:LLC-load-misses
bpf_cookie 0
pids perf_event(19483)
5: perf_event prog 14
event hardware:cpu-cycles
bpf_cookie 0
pids perf_event(19483)
6: perf_event prog 19
tracepoint sched_switch
bpf_cookie 0
pids tracepoint(20947)
7: perf_event prog 26
uprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
bpf_cookie 0
pids uprobe(21973)
8: perf_event prog 27
uretprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
bpf_cookie 0
pids uprobe(21973)
10: perf_event prog 43
kprobe ffffffffb70a9660 kernel_clone
bpf_cookie 0
pids kprobe(35275)
11: perf_event prog 41
kretprobe ffffffffb70a9660 kernel_clone
bpf_cookie 0
pids kprobe(35275)

$ tools/bpf/bpftool/bpftool link show -j
[{"id":3,"type":"perf_event","prog_id":14,"event_type":"software","event_config":"cpu-clock","bpf_cookie":0,"pids":[{"pid":19483,"comm":"perf_event"}]},{"id":4,"type":"perf_event","prog_id":14,"event_type":"hw-cache","event_config":"LLC-load-misses","bpf_cookie":0,"pids":[{"pid":19483,"comm":"perf_event"}]},{"id":5,"type":"perf_event","prog_id":14,"event_type":"hardware","event_config":"cpu-cycles","bpf_cookie":0,"pids":[{"pid":19483,"comm":"perf_event"}]},{"id":6,"type":"perf_event","prog_id":19,"tracepoint":"sched_switch","bpf_cookie":0,"pids":[{"pid":20947,"comm":"tracepoint"}]},{"id":7,"type":"perf_event","prog_id":26,"retprobe":false,"file":"/home/dev/waken/bpf/uprobe/a.out","offset":4920,"bpf_cookie":0,"pids":[{"pid":21973,"comm":"uprobe"}]},{"id":8,"type":"perf_event","prog_id":27,"retprobe":true,"file":"/home/dev/waken/bpf/uprobe/a.out","offset":4920,"bpf_cookie":0,"pids":[{"pid":21973,"comm":"uprobe"}]},{"id":10,"type":"perf_event","prog_id":43,"retprobe":false,"addr":18446744072485508704,"func":"kernel_clone","offset":0,"bpf_cookie":0,"pids":[{"pid":35275,"comm":"kprobe"}]},{"id":11,"type":"perf_event","prog_id":41,"retprobe":true,"addr":18446744072485508704,"func":"kernel_clone","offset":0,"bpf_cookie":0,"pids":[{"pid":35275,"comm":"kprobe"}]}]

For generic perf events, the displayed information in bpftool is limited to
the type and configuration, while other attributes such as sample_period,
sample_freq, etc., are not included.

The kernel function address won't be exposed if it is not permitted by
kptr_restrict. The result as follows when kptr_restrict is 2.

$ tools/bpf/bpftool/bpftool link show
3: perf_event prog 14
event software:cpu-clock
4: perf_event prog 14
event hw-cache:LLC-load-misses
5: perf_event prog 14
event hardware:cpu-cycles
6: perf_event prog 19
tracepoint sched_switch
7: perf_event prog 26
uprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
8: perf_event prog 27
uretprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
10: perf_event prog 43
kprobe kernel_clone
11: perf_event prog 41
kretprobe kernel_clone

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230709025630.3735-11-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>


# 62b57e3d 08-Jul-2023 Yafang Shao <laoar.shao@gmail.com>

bpftool: Add perf event names

Add new functions and macros to get perf event names. These names except
the perf_type_name are all copied from
tool/perf/util/{parse-events,evsel}.c, so that in the future we will
have a good chance to use the same code.

Suggested-by: Jiri Olsa <olsajiri@gmail.com>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230709025630.3735-10-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>


# edd7f49b 08-Jul-2023 Yafang Shao <laoar.shao@gmail.com>

bpftool: Show kprobe_multi link info

Show the already expose kprobe_multi link info in bpftool. The result as
follows,

$ tools/bpf/bpftool/bpftool link show
91: kprobe_multi prog 244
kprobe.multi func_cnt 7
addr func [module]
ffffffff98c44f20 schedule_timeout_interruptible
ffffffff98c44f60 schedule_timeout_killable
ffffffff98c44fa0 schedule_timeout_uninterruptible
ffffffff98c44fe0 schedule_timeout_idle
ffffffffc075b8d0 xfs_trans_get_efd [xfs]
ffffffffc0768a10 xfs_trans_get_buf_map [xfs]
ffffffffc076c320 xfs_trans_get_dqtrx [xfs]
pids kprobe_multi(188367)
92: kprobe_multi prog 244
kretprobe.multi func_cnt 7
addr func [module]
ffffffff98c44f20 schedule_timeout_interruptible
ffffffff98c44f60 schedule_timeout_killable
ffffffff98c44fa0 schedule_timeout_uninterruptible
ffffffff98c44fe0 schedule_timeout_idle
ffffffffc075b8d0 xfs_trans_get_efd [xfs]
ffffffffc0768a10 xfs_trans_get_buf_map [xfs]
ffffffffc076c320 xfs_trans_get_dqtrx [xfs]
pids kprobe_multi(188367)

$ tools/bpf/bpftool/bpftool link show -j
[{"id":91,"type":"kprobe_multi","prog_id":244,"retprobe":false,"func_cnt":7,"funcs":[{"addr":18446744071977586464,"func":"schedule_timeout_interruptible","module":null},{"addr":18446744071977586528,"func":"schedule_timeout_killable","module":null},{"addr":18446744071977586592,"func":"schedule_timeout_uninterruptible","module":null},{"addr":18446744071977586656,"func":"schedule_timeout_idle","module":null},{"addr":18446744072643524816,"func":"xfs_trans_get_efd","module":"xfs"},{"addr":18446744072643578384,"func":"xfs_trans_get_buf_map","module":"xfs"},{"addr":18446744072643592992,"func":"xfs_trans_get_dqtrx","module":"xfs"}],"pids":[{"pid":188367,"comm":"kprobe_multi"}]},{"id":92,"type":"kprobe_multi","prog_id":244,"retprobe":true,"func_cnt":7,"funcs":[{"addr":18446744071977586464,"func":"schedule_timeout_interruptible","module":null},{"addr":18446744071977586528,"func":"schedule_timeout_killable","module":null},{"addr":18446744071977586592,"func":"schedule_timeout_uninterruptible","module":null},{"addr":18446744071977586656,"func":"schedule_timeout_idle","module":null},{"addr":18446744072643524816,"func":"xfs_trans_get_efd","module":"xfs"},{"addr":18446744072643578384,"func":"xfs_trans_get_buf_map","module":"xfs"},{"addr":18446744072643592992,"func":"xfs_trans_get_dqtrx","module":"xfs"}],"pids":[{"pid":188367,"comm":"kprobe_multi"}]}]

When kptr_restrict is 2, the result is,

$ tools/bpf/bpftool/bpftool link show
91: kprobe_multi prog 244
kprobe.multi func_cnt 7
92: kprobe_multi prog 244
kretprobe.multi func_cnt 7

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230709025630.3735-4-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>


# d7e45eb4 17-May-2023 Yafang Shao <laoar.shao@gmail.com>

bpftool: Show target_{obj,btf}_id in tracing link info

The target_btf_id can help us understand which kernel function is
linked by a tracing prog. The target_btf_id and target_obj_id have
already been exposed to userspace, so we just need to show them.

The result as follows,

$ tools/bpf/bpftool/bpftool link show
2: tracing prog 13
prog_type tracing attach_type trace_fentry
target_obj_id 1 target_btf_id 13964
pids trace(10673)

$ tools/bpf/bpftool/bpftool link show -j
[{"id":2,"type":"tracing","prog_id":13,"prog_type":"tracing","attach_type":"trace_fentry","target_obj_id":1,"target_btf_id":13964,"pids":[{"pid":10673,"comm":"trace"}]}]

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230517103126.68372-3-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>


# 74fc8801 21-Apr-2023 Kui-Feng Lee <thinker.li@gmail.com>

bpftool: Show map IDs along with struct_ops links.

A new link type, BPF_LINK_TYPE_STRUCT_OPS, was added to attach
struct_ops to links. (226bc6ae6405) It would be helpful for users to
know which map is associated with the link.

The assumption was that every link is associated with a BPF program, but
this does not hold true for struct_ops. It would be better to display
map_id instead of prog_id for struct_ops links. However, some tools may
rely on the old assumption and need a prog_id. The discussion on the
mailing list suggests that tools should parse JSON format. We will maintain
the existing JSON format by adding a map_id without removing prog_id. As
for plain text format, we will remove prog_id from the header line and add
a map_id for struct_ops links.

Signed-off-by: Kui-Feng Lee <kuifeng@meta.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20230421214131.352662-1-kuifeng@meta.com


# d0fe92fb 21-Apr-2023 Florian Westphal <fw@strlen.de>

tools: bpftool: print netfilter link info

Dump protocol family, hook and priority value:
$ bpftool link
2: netfilter prog 14
ip input prio -128
pids install(3264)
5: netfilter prog 14
ip6 forward prio 21
pids a.out(3387)
9: netfilter prog 14
ip prerouting prio 123
pids a.out(5700)
10: netfilter prog 14
ip input prio 21
pids test2(5701)

v2: Quentin Monnet suggested to also add 'bpftool net' support:

$ bpftool net
xdp:

tc:

flow_dissector:

netfilter:

ip prerouting prio 21 prog_id 14
ip input prio -128 prog_id 14
ip input prio 21 prog_id 14
ip forward prio 21 prog_id 14
ip output prio 21 prog_id 14
ip postrouting prio 21 prog_id 14

'bpftool net' only dumps netfilter link type, links are sorted by protocol
family, hook and priority.

v5: fix bpf ci failure: libbpf needs small update to prog_type_name[]
and probe_prog_load helper.
v4: don't fail with -EOPNOTSUPP in libbpf probe_prog_load, update
prog_type_name[] with "netfilter" entry (bpf ci)
v3: fix bpf.h copy, 'reserved' member was removed (Alexei)
use p_err, not fprintf (Quentin)

Suggested-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/eeeaac99-9053-90c2-aa33-cc1ecb1ae9ca@isovalent.com/
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Link: https://lore.kernel.org/r/20230421170300.24115-6-fw@strlen.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>


# 38f0408e 14-Feb-2023 Ilya Leoshkevich <iii@linux.ibm.com>

bpftool: Use bpf_{btf,link,map,prog}_get_info_by_fd()

Use the new type-safe wrappers around bpf_obj_get_info_by_fd().

Split the bpf_obj_get_info_by_fd() call in build_btf_type_table() in
two, since knowing the type helps with the Memory Sanitizer.

Improve map_parse_fd_and_info() type safety by using
struct bpf_map_info * instead of void * for info.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20230214231221.249277-4-iii@linux.ibm.com


# c302378b 09-Nov-2022 Eduard Zingerman <eddyz87@gmail.com>

libbpf: Hashmap interface update to allow both long and void* keys/values

An update for libbpf's hashmap interface from void* -> void* to a
polymorphic one, allowing both long and void* keys and values.

This simplifies many use cases in libbpf as hashmaps there are mostly
integer to integer.

Perf copies hashmap implementation from libbpf and has to be
updated as well.

Changes to libbpf, selftests/bpf and perf are packed as a single
commit to avoid compilation issues with any future bisect.

Polymorphic interface is acheived by hiding hashmap interface
functions behind auxiliary macros that take care of necessary
type casts, for example:

#define hashmap_cast_ptr(p) \
({ \
_Static_assert((p) == NULL || sizeof(*(p)) == sizeof(long),\
#p " pointee should be a long-sized integer or a pointer"); \
(long *)(p); \
})

bool hashmap_find(const struct hashmap *map, long key, long *value);

#define hashmap__find(map, key, value) \
hashmap_find((map), (long)(key), hashmap_cast_ptr(value))

- hashmap__find macro casts key and value parameters to long
and long* respectively
- hashmap_cast_ptr ensures that value pointer points to a memory
of appropriate size.

This hack was suggested by Andrii Nakryiko in [1].
This is a follow up for [2].

[1] https://lore.kernel.org/bpf/CAEf4BzZ8KFneEJxFAaNCCFPGqp20hSpS2aCj76uRk3-qZUH5xg@mail.gmail.com/
[2] https://lore.kernel.org/bpf/af1facf9-7bc8-8a3d-0db4-7b3f333589a2@meta.com/T/#m65b28f1d6d969fcd318b556db6a3ad499a42607d

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221109142611.879983-2-eddyz87@gmail.com


# 6bdb6d6b 26-Sep-2022 Kui-Feng Lee <kuifeng@fb.com>

bpftool: Show parameters of BPF task iterators.

Show tid or pid of iterators if giving an argument of tid or pid

For example, the command `bpftool link list` may list following
lines.

1: iter prog 2 target_name bpf_map
2: iter prog 3 target_name bpf_prog
33: iter prog 225 target_name task_file tid 1644
pids test_progs(1644)

Link 33 is a task_file iterator with tid 1644. For now, only targets
of task, task_file and task_vma may be with tid or pid to filter out
tasks other than those belonging to a process (pid) or a thread (tid).

Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/bpf/20220926184957.208194-6-kuifeng@fb.com


# 6f95de6d 29-Aug-2022 Hao Luo <haoluo@google.com>

bpftool: Add support for querying cgroup_iter link

Support dumping info of a cgroup_iter link. This includes
showing the cgroup's id and the order for walking the cgroup
hierarchy. Example output is as follows:

> bpftool link show
1: iter prog 2 target_name bpf_map
2: iter prog 3 target_name bpf_prog
3: iter prog 12 target_name cgroup cgroup_id 72 order self_only

> bpftool -p link show
[{
"id": 1,
"type": "iter",
"prog_id": 2,
"target_name": "bpf_map"
},{
"id": 2,
"type": "iter",
"prog_id": 3,
"target_name": "bpf_prog"
},{
"id": 3,
"type": "iter",
"prog_id": 12,
"target_name": "cgroup",
"cgroup_id": 72,
"order": "self_only"
}
]

Signed-off-by: Hao Luo <haoluo@google.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220829231828.1016835-1-haoluo@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@linux.dev>


# c7e7e279 23-May-2022 Daniel Müller <deso@posteo.net>

bpftool: Use libbpf_bpf_link_type_str

This change switches bpftool over to using the recently introduced
libbpf_bpf_link_type_str function instead of maintaining its own string
representation for the bpf_link_type enum.

Signed-off-by: Daniel Müller <deso@posteo.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220523230428.3077108-13-deso@posteo.net


# 1ba5ad36 23-May-2022 Daniel Müller <deso@posteo.net>

bpftool: Use libbpf_bpf_attach_type_str

This change switches bpftool over to using the recently introduced
libbpf_bpf_attach_type_str function instead of maintaining its own
string representation for the bpf_attach_type enum.

Note that contrary to other enum types, the variant names that bpftool
maps bpf_attach_type to do not adhere a simple to follow rule. With
bpf_prog_type, for example, the textual representation can easily be
inferred by stripping the BPF_PROG_TYPE_ prefix and lowercasing the
remaining string. bpf_attach_type violates this rule for various
variants.
We decided to fix up this deficiency with this change, meaning that
bpftool uses the same textual representations as libbpf. Supporting
tests, completion scripts, and man pages have been adjusted accordingly.
However, we did add support for accepting (the now undocumented)
original attach type names when they are provided by users.

For the test (test_bpftool_synctypes.py), I have removed the enum
representation checks, because we no longer mirror the various enum
variant names in bpftool source code. For the man page, help text, and
completion script checks we are now using enum definitions from
uapi/linux/bpf.h as the source of truth directly.

Signed-off-by: Daniel Müller <deso@posteo.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20220523230428.3077108-10-deso@posteo.net


# b700eeb4 23-May-2022 Daniel Müller <deso@posteo.net>

bpftool: Use libbpf_bpf_prog_type_str

This change switches bpftool over to using the recently introduced
libbpf_bpf_prog_type_str function instead of maintaining its own string
representation for the bpf_prog_type enum.

Signed-off-by: Daniel Müller <deso@posteo.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20220523230428.3077108-4-deso@posteo.net


# f7e0beaf 10-May-2022 Kui-Feng Lee <kuifeng@fb.com>

bpf, x86: Generate trampolines from bpf_tramp_links

Replace struct bpf_tramp_progs with struct bpf_tramp_links to collect
struct bpf_tramp_link(s) for a trampoline. struct bpf_tramp_link
extends bpf_link to act as a linked list node.

arch_prepare_bpf_trampoline() accepts a struct bpf_tramp_links to
collects all bpf_tramp_link(s) that a trampoline should call.

Change BPF trampoline and bpf_struct_ops to pass bpf_tramp_links
instead of bpf_tramp_progs.

Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220510205923.3206889-2-kuifeng@fb.com


# fff3dfab 31-Mar-2022 Milan Landaverde <milan@mdaverde.com>

bpftool: Add missing link types

Will display the link type names in bpftool link show output

Signed-off-by: Milan Landaverde <milan@mdaverde.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220331154555.422506-3-milan@mdaverde.com


# 622a5b58 07-Jan-2022 Mauricio Vásquez <mauricio@kinvolk.io>

bpftool: Fix error check when calling hashmap__new()

hashmap__new() encodes errors with ERR_PTR(), hence it's not valid to
check the returned pointer against NULL and IS_ERR() has to be used
instead.

libbpf_get_error() can't be used in this case as hashmap__new() is not
part of the public libbpf API and it'll continue using ERR_PTR() after
libbpf 1.0.

Fixes: 8f184732b60b ("bpftool: Switch to libbpf's hashmap for pinned paths of BPF objects")
Fixes: 2828d0d75b73 ("bpftool: Switch to libbpf's hashmap for programs/maps in BTF listing")
Fixes: d6699f8e0f83 ("bpftool: Switch to libbpf's hashmap for PIDs/names references")
Signed-off-by: Mauricio Vásquez <mauricio@kinvolk.io>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220107152620.192327-2-mauricio@kinvolk.io


# d6699f8e 23-Oct-2021 Quentin Monnet <quentin@isovalent.com>

bpftool: Switch to libbpf's hashmap for PIDs/names references

In order to show PIDs and names for processes holding references to BPF
programs, maps, links, or BTF objects, bpftool creates hash maps to
store all relevant information. This commit is part of a set that
transitions from the kernel's hash map implementation to the one coming
with libbpf.

The motivation is to make bpftool less dependent of kernel headers, to
ease the path to a potential out-of-tree mirror, like libbpf has.

This is the third and final step of the transition, in which we convert
the hash maps used for storing the information about the processes
holding references to BPF objects (programs, maps, links, BTF), and at
last we drop the inclusion of tools/include/linux/hashtable.h.

Note: Checkpatch complains about the use of __weak declarations, and the
missing empty lines after the bunch of empty function declarations when
compiling without the BPF skeletons (none of these were introduced in
this patch). We want to keep things as they are, and the reports should
be safe to ignore.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211023205154.6710-6-quentin@isovalent.com


# 8f184732 23-Oct-2021 Quentin Monnet <quentin@isovalent.com>

bpftool: Switch to libbpf's hashmap for pinned paths of BPF objects

In order to show pinned paths for BPF programs, maps, or links when
listing them with the "-f" option, bpftool creates hash maps to store
all relevant paths under the bpffs. So far, it would rely on the
kernel implementation (from tools/include/linux/hashtable.h).

We can make bpftool rely on libbpf's implementation instead. The
motivation is to make bpftool less dependent of kernel headers, to ease
the path to a potential out-of-tree mirror, like libbpf has.

This commit is the first step of the conversion: the hash maps for
pinned paths for programs, maps, and links are converted to libbpf's
hashmap.{c,h}. Other hash maps used for the PIDs of process holding
references to BPF objects are left unchanged for now. On the build side,
this requires adding a dependency to a second header internal to libbpf,
and making it a dependency for the bootstrap bpftool version as well.
The rest of the changes are a rather straightforward conversion.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211023205154.6710-4-quentin@isovalent.com


# 46241271 23-Oct-2021 Quentin Monnet <quentin@isovalent.com>

bpftool: Do not expose and init hash maps for pinned path in main.c

BPF programs, maps, and links, can all be listed with their pinned paths
by bpftool, when the "-f" option is provided. To do so, bpftool builds
hash maps containing all pinned paths for each kind of objects.

These three hash maps are always initialised in main.c, and exposed
through main.h. There appear to be no particular reason to do so: we can
just as well make them static to the files that need them (prog.c,
map.c, and link.c respectively), and initialise them only when we want
to show objects and the "-f" switch is provided.

This may prevent unnecessary memory allocations if the implementation of
the hash maps was to change in the future.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211023205154.6710-3-quentin@isovalent.com


# c07ba629 30-Jul-2021 Quentin Monnet <quentin@isovalent.com>

tools: bpftool: Update and synchronise option list in doc and help msg

All bpftool commands support the options for JSON output and debug from
libbpf. In addition, some commands support additional options
corresponding to specific use cases.

The list of options described in the man pages for the different
commands are not always accurate. The messages for interactive help are
mostly limited to HELP_SPEC_OPTIONS, and are even less representative of
the actual set of options supported for the commands.

Let's update the lists:

- HELP_SPEC_OPTIONS is modified to contain the "default" options (JSON
and debug), and to be extensible (no ending curly bracket).
- All commands use HELP_SPEC_OPTIONS in their help message, and then
complete the list with their specific options.
- The lists of options in the man pages are updated.
- The formatting of the list for bpftool.rst is adjusted to match
formatting for the other man pages. This is for consistency, and also
because it will be helpful in a future patch to automatically check
that the files are synchronised.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210730215435.7095-5-quentin@isovalent.com


# e60495ea 21-Aug-2020 Yonghong Song <yhs@fb.com>

bpftool: Implement link_query for bpf iterators

The link query for bpf iterators is implemented.
Besides being shown to the user what bpf iterator
the link represents, the target_name is also used
to filter out what additional information should be
printed out, e.g., whether map_id should be shown or not.
The following is an example of bpf_iter link dump,
plain output or pretty output.

$ bpftool link show
11: iter prog 59 target_name task
pids test_progs(1749)
34: iter prog 173 target_name bpf_map_elem map_id 127
pids test_progs_1(1753)
$ bpftool -p link show
[{
"id": 11,
"type": "iter",
"prog_id": 59,
"target_name": "task",
"pids": [{
"pid": 1749,
"comm": "test_progs"
}
]
},{
"id": 34,
"type": "iter",
"prog_id": 173,
"target_name": "bpf_map_elem",
"map_id": 127,
"pids": [{
"pid": 1753,
"comm": "test_progs_1"
}
]
}
]

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200821184420.574430-1-yhs@fb.com


# 09f44b75 13-Aug-2020 Andrii Nakryiko <andriin@fb.com>

tools/bpftool: Fix compilation warnings in 32-bit mode

Fix few compilation warnings in bpftool when compiling in 32-bit mode.
Abstract away u64 to pointer conversion into a helper function.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200813204945.1020225-2-andriin@fb.com


# 0e8c7c07 31-Jul-2020 Andrii Nakryiko <andriin@fb.com>

tools/bpftool: Add `link detach` subcommand

Add ability to force-detach BPF link. Also add missing error message, if
specified link ID is wrong.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200731182830.286260-5-andriin@fb.com


# 9023497d 24-Jun-2020 Tobias Klauser <tklauser@distanz.ch>

tools, bpftool: Define prog_type_name array only once

Define prog_type_name in prog.c instead of main.h so it is only defined
once. This leads to a slight decrease in the binary size of bpftool.

Before:

text data bss dec hex filename
401032 11936 1573160 1986128 1e4e50 bpftool

After:

text data bss dec hex filename
399024 11168 1573160 1983352 1e4378 bpftool

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200624143124.12914-1-tklauser@distanz.ch


# d53dee3f 19-Jun-2020 Andrii Nakryiko <andriin@fb.com>

tools/bpftool: Show info for processes holding BPF map/prog/link/btf FDs

Add bpf_iter-based way to find all the processes that hold open FDs against
BPF object (map, prog, link, btf). bpftool always attempts to discover this,
but will silently give up if kernel doesn't yet support bpf_iter BPF programs.
Process name and PID are emitted for each process (task group).

Sample output for each of 4 BPF objects:

$ sudo ./bpftool prog show
2694: cgroup_device tag 8c42dee26e8cd4c2 gpl
loaded_at 2020-06-16T15:34:32-0700 uid 0
xlated 648B jited 409B memlock 4096B
pids systemd(1)
2907: cgroup_skb name egress tag 9ad187367cf2b9e8 gpl
loaded_at 2020-06-16T18:06:54-0700 uid 0
xlated 48B jited 59B memlock 4096B map_ids 2436
btf_id 1202
pids test_progs(2238417), test_progs(2238445)

$ sudo ./bpftool map show
2436: array name test_cgr.bss flags 0x400
key 4B value 8B max_entries 1 memlock 8192B
btf_id 1202
pids test_progs(2238417), test_progs(2238445)
2445: array name pid_iter.rodata flags 0x480
key 4B value 4B max_entries 1 memlock 8192B
btf_id 1214 frozen
pids bpftool(2239612)

$ sudo ./bpftool link show
61: cgroup prog 2908
cgroup_id 375301 attach_type egress
pids test_progs(2238417), test_progs(2238445)
62: cgroup prog 2908
cgroup_id 375344 attach_type egress
pids test_progs(2238417), test_progs(2238445)

$ sudo ./bpftool btf show
1202: size 1527B prog_ids 2908,2907 map_ids 2436
pids test_progs(2238417), test_progs(2238445)
1242: size 34684B
pids bpftool(2258892)

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200619231703.738941-9-andriin@fb.com


# e948947a 31-May-2020 Jakub Sitnicki <jakub@cloudflare.com>

bpftool: Support link show for netns-attached links

Make `bpf link show` aware of new link type, that is links attached to
netns. When listing netns-attached links, display netns inode number as its
identifier and link attach type.

Sample session:

# readlink /proc/self/ns/net
net:[4026532251]
# bpftool prog show
357: flow_dissector tag a04f5eef06a7f555 gpl
loaded_at 2020-05-30T16:53:51+0200 uid 0
xlated 16B jited 37B memlock 4096B
358: flow_dissector tag a04f5eef06a7f555 gpl
loaded_at 2020-05-30T16:53:51+0200 uid 0
xlated 16B jited 37B memlock 4096B
# bpftool link show
108: netns prog 357
netns_ino 4026532251 attach_type flow_dissector
# bpftool link -jp show
[{
"id": 108,
"type": "netns",
"prog_id": 357,
"netns_ino": 4026532251,
"attach_type": "flow_dissector"
}
]

(... after netns is gone ...)

# bpftool link show
108: netns prog 357
netns_ino 0 attach_type flow_dissector
# bpftool link -jp show
[{
"id": 108,
"type": "netns",
"prog_id": 357,
"netns_ino": 0,
"attach_type": "flow_dissector"
}
]

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200531082846.2117903-9-jakub@cloudflare.com


# be6e1981 31-May-2020 Jakub Sitnicki <jakub@cloudflare.com>

bpftool: Extract helpers for showing link attach type

Code for printing link attach_type is duplicated in a couple of places, and
likely will be duplicated for future link types as well. Create helpers to
prevent duplication.

Suggested-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200531082846.2117903-8-jakub@cloudflare.com


# 90040351 22-May-2020 Quentin Monnet <quentin@isovalent.com>

tools, bpftool: Clean subcommand help messages

This is a clean-up for the formatting of the do_help functions for
bpftool's subcommands. The following fixes are included:

- Do not use argv[-2] for "iter" help message, as the help is shown by
default if no "iter" action is selected, resulting in messages looking
like "./bpftool bpftool pin...".

- Do not print unused HELP_SPEC_PROGRAM in help message for "bpftool
link".

- Andrii used argument indexing to avoid having multiple occurrences of
bin_name and argv[-2] in the fprintf() for the help message, for
"bpftool gen" and "bpftool link". Let's reuse this for all other help
functions. We can remove up to thirty arguments for the "bpftool map"
help message.

- Harmonise all functions, e.g. use ending quotes-comma on a separate
line.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200523010751.23465-1-quentin@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>


# 9406b485 09-May-2020 Yonghong Song <yhs@fb.com>

tools/bpftool: Add bpf_iter support for bptool

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


# c5481f9a 28-Apr-2020 Andrii Nakryiko <andriin@fb.com>

bpftool: Add bpf_link show and pin support

Add `bpftool link show` and `bpftool link pin` commands.

Example plain output for `link show` (with showing pinned paths):

[vmuser@archvm bpf]$ sudo ~/local/linux/tools/bpf/bpftool/bpftool -f link
1: tracing prog 12
prog_type tracing attach_type fentry
pinned /sys/fs/bpf/my_test_link
pinned /sys/fs/bpf/my_test_link2
2: tracing prog 13
prog_type tracing attach_type fentry
3: tracing prog 14
prog_type tracing attach_type fentry
4: tracing prog 15
prog_type tracing attach_type fentry
5: tracing prog 16
prog_type tracing attach_type fentry
6: tracing prog 17
prog_type tracing attach_type fentry
7: raw_tracepoint prog 21
tp 'sys_enter'
8: cgroup prog 25
cgroup_id 584 attach_type egress
9: cgroup prog 25
cgroup_id 599 attach_type egress
10: cgroup prog 25
cgroup_id 614 attach_type egress
11: cgroup prog 25
cgroup_id 629 attach_type egress

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200429001614.1544-9-andriin@fb.com