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SubjectRe: [PATCH v9 perf,bpf 09/15] perf, bpf: save btf information as headers to perf.data
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> On Mar 12, 2019, at 8:16 AM, Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> wrote:
>
> Em Tue, Mar 12, 2019 at 12:14:05PM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Mon, Mar 11, 2019 at 10:30:45PM -0700, Song Liu escreveu:
>>> +static void print_bpf_btf(struct feat_fd *ff, FILE *fp)
>>> +{
>>> + struct perf_env *env = &ff->ph->env;
>>> + struct rb_root *root;
>>> + struct rb_node *next;
>>> +
>>> + down_read(&env->bpf_progs.lock);
>>> +
>>> + root = &env->bpf_progs.btfs;
>>> + next = rb_first(root);
>>> +
>>> + while (next) {
>>> + struct btf_node *node;
>>> +
>>> + node = rb_entry(next, struct btf_node, rb_node);
>>> + next = rb_next(&node->rb_node);
>>> + fprintf(fp, "# btf info of id %u\n", node->id);
>>
>> So, I couldn't get this to work right now, and I have BPF programs that
>> are loaded and that have BTF info:
>>
>> [root@quaco ~]# bpftool prog | tail -6
>> 208: tracepoint name sys_enter tag 819967866022f1e1 gpl
>> loaded_at 2019-03-12T11:16:55-0300 uid 0
>> xlated 528B jited 381B memlock 4096B map_ids 107,106,105
>> 209: tracepoint name sys_exit tag c1bd85c092d6e4aa gpl
>> loaded_at 2019-03-12T11:16:55-0300 uid 0
>> xlated 256B jited 191B memlock 4096B map_ids 107,106
>> [root@quaco ~]#
>>
>>
>> [root@quaco ~]# bpftool map | tail -6
>> 105: perf_event_array name __augmented_sys flags 0x0
>> key 4B value 4B max_entries 8 memlock 4096B
>> 106: array name syscalls flags 0x0
>> key 4B value 1B max_entries 512 memlock 8192B
>> 107: hash name pids_filtered flags 0x0
>> key 4B value 1B max_entries 64 memlock 8192B
>> [root@quaco ~]#
>>
>> [root@quaco ~]# bpftool map dump id 107
>> [{
>> "key": 8104,
>> "value": true
>> },{
>> "key": 18868,
>> "value": true
>> }
>> ]
>> [root@quaco ~]# ps ax|egrep 8104\|18868 | grep -v grep
>> 8104 pts/8 S+ 0:07 trace -e recvmmsg
>> 18868 ? Ssl 21:21 /usr/libexec/gnome-terminal-server
>> [root@quaco ~]#
>>
>> So I was expecting to see those btf lines there :-\
>>
>> All the patches up to this point I have already merged and tested in my
>> local branch.
>>
>> Will continue right after lunch to try to figure out why this BTF info
>> isn't landing on this new header feature...
>
> I've pushed what I have to my git.kernel.org repo, branch
> tmp.perf/bpf-annotate.
>
> git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git tmp.perf/bpf-annotate
>
> The HEAD is this cset.
>
> - Arnaldo

I am not sure I fully understand the problem here.

I can get BTF information from this version:

# ~/perf report --header-only | grep btf
# btf info of id 504

Thanks,
Song

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