perf metric: Encode and use metric-id as qualifier

For a metric like IPC a group of events like {instructions,cycles}:W
would be formed.

If the events names were changed in parsing then the metric expression
parser would fail to find them.

This change makes the event encoding be something like:

  {instructions/metric-id=instructions/, cycles/metric-id=cycles/}

and then uses the evsel's stable metric-id value to locate the events.

This fixes the case that an event is restricted to user because of the
paranoia setting:

  $ echo 2 > /proc/sys/kernel/perf_event_paranoid
  $ perf stat -M IPC /bin/true
   Performance counter stats for '/bin/true':

             150,298      inst_retired.any:u        #      0.77 IPC
             187,095      cpu_clk_unhalted.thread:u

         0.002042731 seconds time elapsed

         0.000000000 seconds user
         0.002377000 seconds sys

Adding the metric-id as a qualifier has a complication in that
qualifiers will become embedded in qualifiers.

For example, msr/tsc/ could become msr/tsc,metric-id=msr/tsc// which
will fail parse-events.

To solve this problem the metric is encoded and decoded for the
metric-id with !<num> standing in for an encoded value.

Previously ! wasn't parsed.

With this msr/tsc/ becomes msr/tsc,metric-id=msr!3tsc!3/

The metric expression parser is changed so that @ isn't changed to /,
instead this is done when the ID is encoded for parse events.

metricgroup__add_metric_non_group() and metricgroup__add_metric_weak_group()
need to inject the metric-id qualifier, so to avoid repetition they are
merged into a single metricgroup__build_event_string with error codes
more rigorously checked.

stat-shadow's prepare_metric() uses the metric-id to match the metricgroup
code.

As "metric-id=..." is added to all events, it is adding during testing
with the fake PMU.

This complicates pmu_str_check code as PE_PMU_EVENT_FAKE won't match as
part of a configuration.

The testing fake PMU case is fixed so that if a known qualifier with an
! is parsed then it isn't reported as a fake PMU.

This is sufficient to pass all testing but it and the original mechanism
are somewhat brittle.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Antonov <alexander.antonov@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrew Kilroy <andrew.kilroy@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Changbin Du <changbin.du@intel.com>
Cc: Denys Zagorui <dzagorui@cisco.com>
Cc: Fabian Hemmer <copy@copy.sh>
Cc: Felix Fietkau <nbd@nbd.name>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jacob Keller <jacob.e.keller@intel.com>
Cc: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joakim Zhang <qiangqing.zhang@nxp.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kees Kook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nicholas Fraser <nfraser@codeweavers.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Riccardo Mancini <rickyman7@gmail.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: ShihCheng Tu <mrtoastcheng@gmail.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Wan Jiabing <wanjiabing@vivo.com>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20211015172132.1162559-17-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 14 insertions, 3 deletions

diff --git a/tools/perf/tests/expr.c b/tools/perf/tests/expr.c
index 718c13e5a0f4..077783223ce0 100644
--- a/tools/perf/tests/expr.c
+++ b/tools/perf/tests/expr.c
@@ -129,9 +129,9 @@ int test__expr(struct test *t __maybe_unused, int subtest __maybe_unused)
 			expr__find_ids("EVENT1\\,param\\=?@ + EVENT2\\,param\\=?@",
 					NULL, ctx) == 0);
 	TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 2);
-	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "EVENT1,param=3/",
+	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "EVENT1,param=3@",
 						    (void **)&val_ptr));
-	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "EVENT2,param=3/",
+	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "EVENT2,param=3@",
 						    (void **)&val_ptr));
 
 	/* Only EVENT1 or EVENT2 need be measured depending on the value of smt_on. */
diff --git a/tools/perf/tests/pmu-events.c b/tools/perf/tests/pmu-events.c
index 71b08c296410..50b1299fe643 100644
--- a/tools/perf/tests/pmu-events.c
+++ b/tools/perf/tests/pmu-events.c
@@ -761,6 +761,7 @@ static int check_parse_id(const char *id, struct parse_events_error *error,
 {
 	struct evlist *evlist;
 	int ret;
+	char *dup, *cur;
 
 	/* Numbers are always valid. */
 	if (is_number(id))
@@ -769,7 +770,17 @@ static int check_parse_id(const char *id, struct parse_events_error *error,
 	evlist = evlist__new();
 	if (!evlist)
 		return -ENOMEM;
-	ret = __parse_events(evlist, id, error, fake_pmu);
+
+	dup = strdup(id);
+	if (!dup)
+		return -ENOMEM;
+
+	for (cur = strchr(dup, '@') ; cur; cur = strchr(++cur, '@'))
+		*cur = '/';
+
+	ret = __parse_events(evlist, dup, error, fake_pmu);
+	free(dup);
+
 	evlist__delete(evlist);
 	return ret;
 }