perf c2c: Use 'peer' as default display for Arm64

Since Arm64 arch doesn't support HITMs flags, this patch changes to use
'peer' as default display if user doesn't specify any type; for other
arches, it still uses 'tot' as default display type if user doesn't
specify it.

This patch changes to call perf_session__new() in an earlier place, so
session environment can be initialized ahead and arch info can be used
for setting display type.
Suggested-by: Ali Saidi <alisaidi@amazon.com>
Reviewed-by: Ali Saidi <alisaidi@amazon.com>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Tested-by: Ali Saidi <alisaidi@amazon.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.garry@huawei.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Like Xu <likexu@tencent.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Timothy Hayes <timothy.hayes@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20220811062451.435810-15-leo.yan@linaro.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-c2c.c

@@ -2878,7 +2878,7 @@ static int setup_callchain(struct evlist *evlist)
 
 static int setup_display(const char *str)
 {
-	const char *display = str ?: "tot";
+	const char *display = str;
 
 	if (!strcmp(display, "tot"))
 		c2c.display = DISPLAY_TOT_HITM;
@@ -3068,27 +3068,39 @@ static int perf_c2c__report(int argc, const char **argv)
 	data.path  = input_name;
 	data.force = symbol_conf.force;
 
+	session = perf_session__new(&data, &c2c.tool);
+	if (IS_ERR(session)) {
+		err = PTR_ERR(session);
+		pr_debug("Error creating perf session\n");
+		goto out;
+	}
+
+	/*
+	 * Use the 'tot' as default display type if user doesn't specify it;
+	 * since Arm64 platform doesn't support HITMs flag, use 'peer' as the
+	 * default display type.
+	 */
+	if (!display) {
+		if (!strcmp(perf_env__arch(&session->header.env), "arm64"))
+			display = "peer";
+		else
+			display = "tot";
+	}
+
 	err = setup_display(display);
 	if (err)
-		goto out;
+		goto out_session;
 
 	err = setup_coalesce(coalesce, no_source);
 	if (err) {
 		pr_debug("Failed to initialize hists\n");
-		goto out;
+		goto out_session;
 	}
 
 	err = c2c_hists__init(&c2c.hists, "dcacheline", 2);
 	if (err) {
 		pr_debug("Failed to initialize hists\n");
-		goto out;
-	}
-
-	session = perf_session__new(&data, &c2c.tool);
-	if (IS_ERR(session)) {
-		err = PTR_ERR(session);
-		pr_debug("Error creating perf session\n");
-		goto out;
+		goto out_session;
 	}
 
 	session->itrace_synth_opts = &itrace_synth_opts;
@@ -3096,7 +3108,7 @@ static int perf_c2c__report(int argc, const char **argv)
 	err = setup_nodes(session);
 	if (err) {
 		pr_err("Failed setup nodes\n");
-		goto out;
+		goto out_session;
 	}
 
 	err = mem2node__init(&c2c.mem2node, &session->header.env);