Re: [PATCH 03/10] perf record: Add BPF event filter support

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On March 15, 2023 1:41:29 PM GMT-03:00, Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>Hi Arnaldo,
>
>On Wed, Mar 15, 2023 at 6:47 AM Arnaldo Carvalho de Melo
><acme@xxxxxxxxxx> wrote:
>>
>> Em Tue, Mar 14, 2023 at 04:42:30PM -0700, Namhyung Kim escreveu:
>> > Use --filter option to set BPF filter for generic events other than the
>> > tracepoints or Intel PT.  The BPF program will check the sample data and
>> > filter according to the expression.
>> >
>> > For example, the below is the typical perf record for frequency mode.
>> > The sample period started from 1 and increased gradually.
>> >
>> > $ sudo ./perf record -e cycles true
>> > $ sudo ./perf script
>> >        perf-exec 2272336 546683.916875:          1 cycles:  ffffffff828499b8 perf_event_exec+0x298 ([kernel.kallsyms])
>> >        perf-exec 2272336 546683.916892:          1 cycles:  ffffffff828499b8 perf_event_exec+0x298 ([kernel.kallsyms])
>> >        perf-exec 2272336 546683.916899:          3 cycles:  ffffffff828499b8 perf_event_exec+0x298 ([kernel.kallsyms])
>> >        perf-exec 2272336 546683.916905:         17 cycles:  ffffffff828499b8 perf_event_exec+0x298 ([kernel.kallsyms])
>> >        perf-exec 2272336 546683.916911:        100 cycles:  ffffffff828499b8 perf_event_exec+0x298 ([kernel.kallsyms])
>> >        perf-exec 2272336 546683.916917:        589 cycles:  ffffffff828499b8 perf_event_exec+0x298 ([kernel.kallsyms])
>> >        perf-exec 2272336 546683.916924:       3470 cycles:  ffffffff828499b8 perf_event_exec+0x298 ([kernel.kallsyms])
>> >        perf-exec 2272336 546683.916930:      20465 cycles:  ffffffff828499b8 perf_event_exec+0x298 ([kernel.kallsyms])
>> >             true 2272336 546683.916940:     119873 cycles:  ffffffff8283afdd perf_iterate_ctx+0x2d ([kernel.kallsyms])
>> >             true 2272336 546683.917003:     461349 cycles:  ffffffff82892517 vma_interval_tree_insert+0x37 ([kernel.kallsyms])
>> >             true 2272336 546683.917237:     635778 cycles:  ffffffff82a11400 security_mmap_file+0x20 ([kernel.kallsyms])
>> >
>> > When you add a BPF filter to get samples having periods greater than 1000,
>> > the output would look like below:
>>
>> Had to add:
>>
>> diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
>> index be336f1b2b689602..153a13cdca9df1ea 100644
>> --- a/tools/perf/util/python.c
>> +++ b/tools/perf/util/python.c
>> @@ -19,6 +19,7 @@
>>  #include "mmap.h"
>>  #include "stat.h"
>>  #include "metricgroup.h"
>> +#include "util/bpf-filter.h"
>>  #include "util/env.h"
>>  #include "util/pmu.h"
>>  #include <internal/lib.h>
>> @@ -135,6 +136,18 @@ int bpf_counter__disable(struct evsel *evsel __maybe_unused)
>>         return 0;
>>  }
>>
>> +// not to drag util/bpf-filter.c
>> +
>> +int perf_bpf_filter__prepare(struct evsel *evsel __maybe_unused)
>> +{
>> +       return 0;
>> +}
>> +
>> +int perf_bpf_filter__destroy(struct evsel *evsel __maybe_unused)
>> +{
>> +       return 0;
>> +}
>> +
>>  /*
>>   * Support debug printing even though util/debug.c is not linked.  That means
>>   * implementing 'verbose' and 'eprintf'.
>>
>>
>> Please run 'perf test' before submitting patches,
>
>Ugh, sorry.  I think I ran it at some point but missed the python test :-p
>
>Anyway, I'm afraid you need to enclose with #ifndef HAVE_BPF_SKEL.

Right, I noticed that

>
>Thanks,
>Namhyung
>
>
>>
>> - Arnaldo
>>
>> > $ sudo ./perf record -e cycles --filter 'period > 1000' true
>> > $ sudo ./perf script
>> >        perf-exec 2273949 546850.708501:       5029 cycles:  ffffffff826f9e25 finish_wait+0x5 ([kernel.kallsyms])
>> >        perf-exec 2273949 546850.708508:      32409 cycles:  ffffffff826f9e25 finish_wait+0x5 ([kernel.kallsyms])
>> >        perf-exec 2273949 546850.708526:     143369 cycles:  ffffffff82b4cdbf xas_start+0x5f ([kernel.kallsyms])
>> >        perf-exec 2273949 546850.708600:     372650 cycles:  ffffffff8286b8f7 __pagevec_lru_add+0x117 ([kernel.kallsyms])
>> >        perf-exec 2273949 546850.708791:     482953 cycles:  ffffffff829190de __mod_memcg_lruvec_state+0x4e ([kernel.kallsyms])
>> >             true 2273949 546850.709036:     501985 cycles:  ffffffff828add7c tlb_gather_mmu+0x4c ([kernel.kallsyms])
>> >             true 2273949 546850.709292:     503065 cycles:      7f2446d97c03 _dl_map_object_deps+0x973 (/usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2)
>> >
>> > Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
>> > Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
>> > ---
>> >  tools/perf/Documentation/perf-record.txt | 15 +++++++++++---
>> >  tools/perf/util/bpf_counter.c            |  3 +--
>> >  tools/perf/util/evlist.c                 | 25 +++++++++++++++++-------
>> >  tools/perf/util/evsel.c                  |  2 ++
>> >  tools/perf/util/parse-events.c           |  8 +++-----
>> >  5 files changed, 36 insertions(+), 17 deletions(-)
>> >
>> > diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
>> > index ff815c2f67e8..122f71726eaa 100644
>> > --- a/tools/perf/Documentation/perf-record.txt
>> > +++ b/tools/perf/Documentation/perf-record.txt
>> > @@ -119,9 +119,12 @@ OPTIONS
>> >         "perf report" to view group events together.
>> >
>> >  --filter=<filter>::
>> > -        Event filter. This option should follow an event selector (-e) which
>> > -     selects either tracepoint event(s) or a hardware trace PMU
>> > -     (e.g. Intel PT or CoreSight).
>> > +     Event filter.  This option should follow an event selector (-e).
>> > +     If the event is a tracepoint, the filter string will be parsed by
>> > +     the kernel.  If the event is a hardware trace PMU (e.g. Intel PT
>> > +     or CoreSight), it'll be processed as an address filter.  Otherwise
>> > +     it means a general filter using BPF which can be applied for any
>> > +     kind of event.
>> >
>> >       - tracepoint filters
>> >
>> > @@ -176,6 +179,12 @@ OPTIONS
>> >
>> >       Multiple filters can be separated with space or comma.
>> >
>> > +     - bpf filters
>> > +
>> > +     A BPF filter can access the sample data and make a decision based on the
>> > +     data.  Users need to set an appropriate sample type to use the BPF
>> > +     filter.
>> > +
>> >  --exclude-perf::
>> >       Don't record events issued by perf itself. This option should follow
>> >       an event selector (-e) which selects tracepoint event(s). It adds a
>> > diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c
>> > index aa78a15a6f0a..1b77436e067e 100644
>> > --- a/tools/perf/util/bpf_counter.c
>> > +++ b/tools/perf/util/bpf_counter.c
>> > @@ -763,8 +763,7 @@ extern struct bpf_counter_ops bperf_cgrp_ops;
>> >
>> >  static inline bool bpf_counter_skip(struct evsel *evsel)
>> >  {
>> > -     return list_empty(&evsel->bpf_counter_list) &&
>> > -             evsel->follower_skel == NULL;
>> > +     return evsel->bpf_counter_ops == NULL;
>> >  }
>> >
>> >  int bpf_counter__install_pe(struct evsel *evsel, int cpu_map_idx, int fd)
>> > diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
>> > index b74e12239aec..cc491a037836 100644
>> > --- a/tools/perf/util/evlist.c
>> > +++ b/tools/perf/util/evlist.c
>> > @@ -31,6 +31,7 @@
>> >  #include "util/evlist-hybrid.h"
>> >  #include "util/pmu.h"
>> >  #include "util/sample.h"
>> > +#include "util/bpf-filter.h"
>> >  #include <signal.h>
>> >  #include <unistd.h>
>> >  #include <sched.h>
>> > @@ -1086,17 +1087,27 @@ int evlist__apply_filters(struct evlist *evlist, struct evsel **err_evsel)
>> >       int err = 0;
>> >
>> >       evlist__for_each_entry(evlist, evsel) {
>> > -             if (evsel->filter == NULL)
>> > -                     continue;
>> > -
>> >               /*
>> >                * filters only work for tracepoint event, which doesn't have cpu limit.
>> >                * So evlist and evsel should always be same.
>> >                */
>> > -             err = perf_evsel__apply_filter(&evsel->core, evsel->filter);
>> > -             if (err) {
>> > -                     *err_evsel = evsel;
>> > -                     break;
>> > +             if (evsel->filter) {
>> > +                     err = perf_evsel__apply_filter(&evsel->core, evsel->filter);
>> > +                     if (err) {
>> > +                             *err_evsel = evsel;
>> > +                             break;
>> > +                     }
>> > +             }
>> > +
>> > +             /*
>> > +              * non-tracepoint events can have BPF filters.
>> > +              */
>> > +             if (!list_empty(&evsel->bpf_filters)) {
>> > +                     err = perf_bpf_filter__prepare(evsel);
>> > +                     if (err) {
>> > +                             *err_evsel = evsel;
>> > +                             break;
>> > +                     }
>> >               }
>> >       }
>> >
>> > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
>> > index a83d8cd5eb51..dc3faf005c3b 100644
>> > --- a/tools/perf/util/evsel.c
>> > +++ b/tools/perf/util/evsel.c
>> > @@ -50,6 +50,7 @@
>> >  #include "off_cpu.h"
>> >  #include "../perf-sys.h"
>> >  #include "util/parse-branch-options.h"
>> > +#include "util/bpf-filter.h"
>> >  #include <internal/xyarray.h>
>> >  #include <internal/lib.h>
>> >  #include <internal/threadmap.h>
>> > @@ -1517,6 +1518,7 @@ void evsel__exit(struct evsel *evsel)
>> >       assert(list_empty(&evsel->core.node));
>> >       assert(evsel->evlist == NULL);
>> >       bpf_counter__destroy(evsel);
>> > +     perf_bpf_filter__destroy(evsel);
>> >       evsel__free_counts(evsel);
>> >       perf_evsel__free_fd(&evsel->core);
>> >       perf_evsel__free_id(&evsel->core);
>> > diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
>> > index 3b2e5bb3e852..6c5cf5244486 100644
>> > --- a/tools/perf/util/parse-events.c
>> > +++ b/tools/perf/util/parse-events.c
>> > @@ -28,6 +28,7 @@
>> >  #include "perf.h"
>> >  #include "util/parse-events-hybrid.h"
>> >  #include "util/pmu-hybrid.h"
>> > +#include "util/bpf-filter.h"
>> >  #include "tracepoint.h"
>> >  #include "thread_map.h"
>> >
>> > @@ -2542,11 +2543,8 @@ static int set_filter(struct evsel *evsel, const void *arg)
>> >               perf_pmu__scan_file(pmu, "nr_addr_filters",
>> >                                   "%d", &nr_addr_filters);
>> >
>> > -     if (!nr_addr_filters) {
>> > -             fprintf(stderr,
>> > -                     "This CPU does not support address filtering\n");
>> > -             return -1;
>> > -     }
>> > +     if (!nr_addr_filters)
>> > +             return perf_bpf_filter__parse(&evsel->bpf_filters, str);
>> >
>> >       if (evsel__append_addr_filter(evsel, str) < 0) {
>> >               fprintf(stderr,
>> > --
>> > 2.40.0.rc1.284.g88254d51c5-goog
>> >
>>
>> --
>>
>> - Arnaldo




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