On Sun, Mar 26, 2023 at 6:51 PM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote:
>
> Yafang Shao <laoar.shao@xxxxxxxxx> writes:
>
> > We only expose the bpf map id under current bpf namespace to user. The
> > map->id is still the id in the init bpf namespace.
> >
> > The result as follows,
> >
> > Run bpftool in a new bpf namespace
> > $ bpftool map show
> > 4: array name kprobe_b.rodata flags 0x80
> > key 4B value 37B max_entries 1 memlock 360B
> > btf_id 159 frozen
>
> The btf_id is identical for all the different objects in this example
> output; surely that can't be right? Copy-paste error? Same thing in the
> other patches...
>
The bpf progs {"kretprobe_run","kprobe_run"} and the bpf maps
{"kprobe_b.rodata","kprobe_b.data"} belong to the same bpf program. So
the btf_id of them are always the same. For example, below is the
result when I rerun it on my test server,
$ bpftool btf show
...
943: name <anon> size 1086B prog_ids 48824,48822 map_ids 43712,43711
pids kprobe(3599801)
...
$ bpftool map show
43711: array name kprobe_b.rodata flags 0x80
key 4B value 37B max_entries 1 memlock 360B
btf_id 943 frozen
pids kprobe(3599801)
43712: array name kprobe_b.data flags 0x400
key 4B value 4B max_entries 1 memlock 8192B
btf_id 943
pids kprobe(3599801)
$ bpftool prog show
48822: kprobe name kretprobe_run tag 0de47cc241a2b1b3 gpl
loaded_at 2023-03-27T10:35:01+0800 uid 0
xlated 112B jited 78B memlock 4096B map_ids 43711
btf_id 943
pids kprobe(3599801)
48824: kprobe name kprobe_run tag bf163b23cd3b174d gpl
loaded_at 2023-03-27T10:35:01+0800 uid 0
xlated 104B jited 75B memlock 4096B map_ids 43711
btf_id 943
pids kprobe(3599801)
The btf_id hasn't been added into the bpf namespace, so the btf id in
init bpf namespace and child bpf namespace are the same value.
--
Regards
Yafang
