Subject: Re: [PATCH v11 perf, bpf-next 7/9] perf tools: synthesize PERF_RECORD_* for loaded BPF programs

From: Arnaldo Carvalho de Melo <[email-masked]>
Date: Tue, 22 Jan 2019 12:48:15 -0200

Em Tue, Jan 22, 2019 at 12:31:17PM -0200, Arnaldo Carvalho de Melo escreveu:
> Em Tue, Jan 22, 2019 at 12:13:20PM -0200, Arnaldo Carvalho de Melo escreveu:
> > Em Fri, Jan 18, 2019 at 11:46:55AM -0300, Arnaldo Carvalho de Melo escreveu:
> > > Em Thu, Jan 17, 2019 at 08:15:19AM -0800, Song Liu escreveu:
> > > > This patch synthesize PERF_RECORD_KSYMBOL and PERF_RECORD_BPF_EVENT for
> > > > BPF programs loaded before perf-record. This is achieved by gathering
> > > > information about all BPF programs via sys_bpf.
> > > 
> > > Ditto
> > 
> > This is breaking 'perf sched', see below, the fix seems trivial:
> > 
> > [root@quaco ~]# perf sched record -a sleep 2
> > [ perf record: Woken up 1 times to write data ]
> > 0x5b60 [0x138]: failed to process type: 17
> > [ perf record: Captured and wrote 1.539 MB perf.data ]
> > [root@quaco ~]# perf sched lat
> > 0x5b60 [0x138]: failed to process type: 17
> > Failed to process events, error -22
> > [root@quaco ~]#
> 
> So:
> 
>    perf_session__process_event (event->header.type = 17 (PERF_RECORD_KSYMBOL)
>      if (tool->ordered_events)
>        ret = perf_evlist__parse_sample_timestamp(evlist, event, &timestamp);
>        if (ret && ret != -1)
>             return ret;
> 
> So it returns here with -EFAULT, i.e. this is failing:
> 
> int perf_evlist__parse_sample_timestamp(struct perf_evlist *evlist,
>                                         union perf_event *event,
>                                         u64 *timestamp)
> {
>         struct perf_evsel *evsel = perf_evlist__event2evsel(evlist, event);
> 
>         if (!evsel)
>                 return -EFAULT;
>         return perf_evsel__parse_sample_timestamp(evsel, event, timestamp);
> }
> 
> It isn't mapping the event ID it finds back to an evsel.. Jiri, ideas?
> 
> This is happening so far only for 'perf sched', perf record with two
> events works.

So it fails for tracepoints with plain 'perf record':

[root@quaco tmp]# perf record -e sched:sched* sleep 1
[ perf record: Woken up 29 times to write data ]
0x6658 [0x138]: failed to process type: 17
[ perf record: Captured and wrote 0.029 MB perf.data ]
[root@quaco tmp]# perf script
0x6658 [0x138]: failed to process type: 17
[root@quaco tmp]#

[ perf record: Woken up 1 times to write data ]

Breakpoint 1, reader__process_events (rd=0x7ffffffe4160, session=0xab66a0, prog=0x7ffffffe4180) at util/session.c:1911
1911			pr_err("%#" PRIx64 " [%#x]: failed to process type: %d\n",
Missing separate debuginfos, use: dnf debuginfo-install bzip2-libs-1.0.6-28.fc29.x86_64 elfutils-libelf-0.174-5.fc29.x86_64 elfutils-libs-0.174-5.fc29.x86_64 glib2-2.58.2-1.fc29.x86_64 libbabeltrace-1.5.6-1.fc29.x86_64 libunwind-1.2.1-6.fc29.x86_64 libuuid-2.32.1-1.fc29.x86_64 libxcrypt-4.4.2-3.fc29.x86_64 numactl-libs-2.0.12-1.fc29.x86_64 openssl-libs-1.1.1a-1.fc29.x86_64 pcre-8.42-6.fc29.x86_64 perl-libs-5.28.1-427.fc29.x86_64 popt-1.16-15.fc29.x86_64 python2-libs-2.7.15-11.fc29.x86_64 slang-2.3.2-4.fc29.x86_64 xz-libs-5.2.4-3.fc29.x86_64
(gdb) bt
#0  reader__process_events (rd=0x7ffffffe4160, session=0xab66a0, prog=0x7ffffffe4180) at util/session.c:1911
#1  0x0000000000540deb in __perf_session__process_events (session=0xab66a0) at util/session.c:1955
#2  0x0000000000540f1c in perf_session__process_events (session=0xab66a0) at util/session.c:1988
#3  0x0000000000445feb in process_buildids (rec=0x9202a0 <record>) at builtin-record.c:689
#4  0x0000000000446597 in record__finish_output (rec=0x9202a0 <record>) at builtin-record.c:846
#5  0x0000000000447b8c in __cmd_record (rec=0x9202a0 <record>, argc=2, argv=0xab4720) at builtin-record.c:1429
#6  0x0000000000448d64 in cmd_record (argc=2, argv=0xab4720) at builtin-record.c:2153
#7  0x00000000004406dd in __cmd_record (argc=3, argv=0x7fffffffdb30) at builtin-sched.c:3339
#8  0x00000000004411ff in cmd_sched (argc=3, argv=0x7fffffffdb30) at builtin-sched.c:3486
#9  0x00000000004d46e3 in run_builtin (p=0x932c50 <commands+432>, argc=4, argv=0x7fffffffdb30) at perf.c:302
#10 0x00000000004d4950 in handle_internal_command (argc=4, argv=0x7fffffffdb30) at perf.c:354
#11 0x00000000004d4a9f in run_argv (argcp=0x7fffffffd98c, argv=0x7fffffffd980) at perf.c:398
#12 0x00000000004d4e0b in main (argc=4, argv=0x7fffffffdb30) at perf.c:520
(gdb)

[root@quaco tmp]# perf c2c record
^C[ perf record: Woken up 1 times to write data ]
0x5698 [0x138]: failed to process type: 17
[ perf record: Captured and wrote 7.110 MB perf.data ]

[root@quaco tmp]# perf kmem record
^C[ perf record: Woken up 1 times to write data ]
0x5998 [0x138]: failed to process type: 17
[ perf record: Captured and wrote 1.470 MB perf.data ]

[root@quaco tmp]#