Subject: Re: [PATCH v9 perf,bpf 09/15] perf, bpf: save btf information as headers to perf.data

From: Arnaldo Carvalho de Melo <[email-masked]>
Date: Tue, 12 Mar 2019 12:16:08 -0300

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