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SubjectRe: [BUG] perf: intel_pt won't display kernel function
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> On Apr 3, 2019, at 11:50 AM, Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> wrote:
>
> Em Wed, Apr 03, 2019 at 04:27:56PM +0000, Song Liu escreveu:
>>
>>
>>> On Apr 3, 2019, at 8:15 AM, Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> wrote:
>>>
>>> Em Wed, Apr 03, 2019 at 11:53:53AM -0300, Arnaldo Carvalho de Melo escreveu:
>>>> Em Wed, Apr 03, 2019 at 04:37:38PM +0200, Jiri Olsa escreveu:
>>>>> hi,
>>>>> perf script --call-trace stop working for me recently,
>>>>> and displays only user space functions
>>>>>
>>>>> I bisected that to:
>>>>> 7b612e291a5a perf tools: Synthesize PERF_RECORD_* for loaded BPF programs
>>>>>
>>>>> data from following comands will display user space functions only:
>>>>> # perf-with-kcore record pt -e intel_pt// -- ls
>>>>> # perf-with-kcore script pt --call-trace
>>>>>
>>>>> when I disable the bpf synthesizing (patch below), kernel functions are back
>>>>>
>>>>> I guess the new events mess up with intel_pt decoder somehow
>>>>
>>>> I.e. I'm adding the patch below to my perf/urgent branch.
>>>
>>> Song, that is what I have, can I have your Acked-by and please consider
>>> taking a look at the bug Jiri reported,
>>>
>>> Thanks,
>>>
>>> - Arnaldo
>>
>> Current logic with --no-bpf-event is to generate PERF_RECORD_KSYMBOL, but not
>> PERF_RECORD_BPF_EVENT:
>
> I see... The opts is done later, after querying the kernel for existing
> BPF programs so that at least the KSYMBOL ones can be generated. So I'll
> keep it as is, no need for this patch.
>
>> https://urldefense.proofpoint.com/v2/url?u=https-3A__elixir.bootlin.com_linux_v5.1-2Drc3_source_tools_perf_util_bpf-2Devent.c-23L254&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=8ITYgIrqFBIy1uQFQPHrsX5kBX5RlmhwcknKYJa2eGs&s=MdB2zA9JstwC93qKEonsfTQeQYiw-yeOLbPxm3QMRo8&e=
>>
>> I will look into the intel_pt problem.
>
> Ok.
>
>> In the meanwhile, let's fix it for now.
>
> I'll wait a bit.

I guess something like this might be a better fix? (Sorry for missing
commit message):

diff --git i/tools/perf/util/map.c w/tools/perf/util/map.c
index e32628cd20a7..741430a35dca 100644
--- i/tools/perf/util/map.c
+++ w/tools/perf/util/map.c
@@ -261,6 +261,12 @@ bool __map__is_extra_kernel_map(const struct map *map)
return kmap && kmap->name[0];
}

+bool __map__is_bpf_prog(const struct map *map)
+{
+ const char *name = map->dso->short_name;
+ return name && (strstr(name, "bpf_prog_") == name);
+}
+
bool map__has_symbols(const struct map *map)
{
return dso__has_symbols(map->dso);
diff --git i/tools/perf/util/map.h w/tools/perf/util/map.h
index 0e20749f2c55..01079f1f4375 100644
--- i/tools/perf/util/map.h
+++ w/tools/perf/util/map.h
@@ -159,10 +159,12 @@ int map__set_kallsyms_ref_reloc_sym(struct map *map, const char *symbol_name,

bool __map__is_kernel(const struct map *map);
bool __map__is_extra_kernel_map(const struct map *map);
+bool __map__is_bpf_prog(const struct map *map);

static inline bool __map__is_kmodule(const struct map *map)
{
- return !__map__is_kernel(map) && !__map__is_extra_kernel_map(map);
+ return !__map__is_kernel(map) && !__map__is_extra_kernel_map(map) &&
+ !__map__is_bpf_prog(map);
}

bool map__has_symbols(const struct map *map);
Thanks,
Song

>
>> Acked-by: Song Liu <songliubraving@fb.com>
>>
>> Thanks,
>> Song
>>
>>
>>> commit 011318ccc2024ba03e96c32a06f74ca5d6ab5503
>>> Author: Arnaldo Carvalho de Melo <acme@redhat.com>
>>> Date: Wed Apr 3 12:05:15 2019 -0300
>>>
>>> perf record: Do not synthesize BPF records when --no-bpf-event is used
>>>
>>> By default we synthesize and ask the kernel for BPF events, having a
>>> --no-bpf-event option to disable that, which can be useful, for
>>> instance, if there are still bugs in that code, which seems to be the
>>> case as reported by Jiri Olsa in:
>>>
>>> "[BUG] perf: intel_pt won't display kernel function"
>>> https://lore.kernel.org/lkml/20190403143738.GB32001@krava
>>>
>>> So add the check for record_opts.no_bpf_event when considering
>>> synthesizing BPF events for pre-existing BPF programs in 'perf record'.
>>>
>>> The reported bug needs further analysis and is a separate matter.
>>>
>>> Cc: Adrian Hunter <adrian.hunter@intel.com>
>>> Cc: Alexei Starovoitov <ast@kernel.org>
>>> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
>>> Cc: Daniel Borkmann <daniel@iogearbox.net>
>>> Cc: Jiri Olsa <jolsa@kernel.org>
>>> Cc: Martin KaFai Lau <kafai@fb.com>
>>> Cc: Namhyung Kim <namhyung@kernel.org>
>>> Cc: Peter Zijlstra <peterz@infradead.org>
>>> Cc: Song Liu <songliubraving@fb.com>
>>> Cc: Yonghong Song <yhs@fb.com>
>>> Fixes: 7b612e291a5a ("perf tools: Synthesize PERF_RECORD_* for loaded BPF programs")
>>> Link: https://lore.kernel.org/lkml/20190403145353.GE32553@kernel.org
>>> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
>>>
>>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>>> index 4e2d953d4bc5..17d772f192ad 100644
>>> --- a/tools/perf/builtin-record.c
>>> +++ b/tools/perf/builtin-record.c
>>> @@ -1114,10 +1114,11 @@ static int record__synthesize(struct record *rec, bool tail)
>>> return err;
>>> }
>>>
>>> - err = perf_event__synthesize_bpf_events(session, process_synthesized_event,
>>> - machine, opts);
>>> - if (err < 0)
>>> - pr_warning("Couldn't synthesize bpf events.\n");
>>> + if (!opts->no_bpf_event) {
>>> + err = perf_event__synthesize_bpf_events(session, process_synthesized_event, machine, opts);
>>> + if (err < 0)
>>> + pr_warning("Couldn't synthesize bpf events.\n");
>>> + }
>>>
>>> err = __machine__synthesize_threads(machine, tool, &opts->target, rec->evlist->threads,
>>> process_synthesized_event, opts->sample_address,
>
> --
>
> - Arnaldo

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