perf auxtrace: Add mmap_needed to auxtrace_mmap_params

Add mmap_needed to auxtrace_mmap_params.

Currently an auxtrace mmap is always attempted even if the event is not an
auxtrace event. That works because, when AUX area tracing, there is always
an auxtrace event first for every mmap. Prepare for that not being the
case, which it won't be when sideband tracking events are allowed on
all CPUs even when auxtrace is limited to selected CPUs.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Link: https://lore.kernel.org/r/20220524075436.29144-3-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/auxtrace.c

@@ -125,7 +125,7 @@ int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,
 	mm->tid = mp->tid;
 	mm->cpu = mp->cpu.cpu;
 
-	if (!mp->len) {
+	if (!mp->len || !mp->mmap_needed) {
 		mm->base = NULL;
 		return 0;
 	}
@@ -168,9 +168,15 @@ void auxtrace_mmap_params__init(struct auxtrace_mmap_params *mp,
 }
 
 void auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp,
-				   struct evlist *evlist, int idx,
+				   struct evlist *evlist,
+				   struct evsel *evsel, int idx,
 				   bool per_cpu)
 {
+	mp->mmap_needed = evsel->needs_auxtrace_mmap;
+
+	if (!mp->mmap_needed)
+		return;
+
 	mp->idx = idx;
 
 	if (per_cpu) {

tools/perf/util/auxtrace.h

@@ -344,6 +344,10 @@ struct auxtrace_mmap {
  * @idx: index of this mmap
  * @tid: tid for a per-thread mmap (also set if there is only 1 tid on a per-cpu
  *       mmap) otherwise %0
+ * @mmap_needed: set to %false for non-auxtrace events. This is needed because
+ *               auxtrace mmapping is done in the same code path as non-auxtrace
+ *               mmapping but not every evsel that needs non-auxtrace mmapping
+ *               also needs auxtrace mmapping.
  * @cpu: cpu number for a per-cpu mmap otherwise %-1
  */
 struct auxtrace_mmap_params {
@@ -353,6 +357,7 @@ struct auxtrace_mmap_params {
 	int		prot;
 	int		idx;
 	pid_t		tid;
+	bool		mmap_needed;
 	struct perf_cpu	cpu;
 };
 
@@ -490,7 +495,8 @@ void auxtrace_mmap_params__init(struct auxtrace_mmap_params *mp,
 				unsigned int auxtrace_pages,
 				bool auxtrace_overwrite);
 void auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp,
-				   struct evlist *evlist, int idx,
+				   struct evlist *evlist,
+				   struct evsel *evsel, int idx,
 				   bool per_cpu);
 
 typedef int (*process_auxtrace_t)(struct perf_tool *tool,
@@ -863,7 +869,8 @@ void auxtrace_mmap_params__init(struct auxtrace_mmap_params *mp,
 				unsigned int auxtrace_pages,
 				bool auxtrace_overwrite);
 void auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp,
-				   struct evlist *evlist, int idx,
+				   struct evlist *evlist,
+				   struct evsel *evsel, int idx,
 				   bool per_cpu);
 
 #define ITRACE_HELP ""

tools/perf/util/evlist.c

@@ -747,15 +747,16 @@ static struct mmap *evlist__alloc_mmap(struct evlist *evlist,
 
 static void
 perf_evlist__mmap_cb_idx(struct perf_evlist *_evlist,
-			 struct perf_evsel *_evsel __maybe_unused,
+			 struct perf_evsel *_evsel,
 			 struct perf_mmap_param *_mp,
 			 int idx)
 {
 	struct evlist *evlist = container_of(_evlist, struct evlist, core);
 	struct mmap_params *mp = container_of(_mp, struct mmap_params, core);
 	bool per_cpu = !perf_cpu_map__empty(_evlist->user_requested_cpus);
+	struct evsel *evsel = container_of(_evsel, struct evsel, core);
 
-	auxtrace_mmap_params__set_idx(&mp->auxtrace_mp, evlist, idx, per_cpu);
+	auxtrace_mmap_params__set_idx(&mp->auxtrace_mp, evlist, evsel, idx, per_cpu);
 }
 
 static struct perf_mmap*

tools/perf/util/mmap.c

@@ -62,6 +62,7 @@ void __weak auxtrace_mmap_params__init(struct auxtrace_mmap_params *mp __maybe_u
 
 void __weak auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp __maybe_unused,
 					  struct evlist *evlist __maybe_unused,
+					  struct evsel *evsel __maybe_unused,
 					  int idx __maybe_unused,
 					  bool per_cpu __maybe_unused)
 {