[PATCH v3 3/3] perf evlist: Improve default event for s390

[Ian Rogers <irogers@google.com>]

Frame pointer callchains are not supported on s390 and dwarf
callchains are only supported on software events.

Switch the default event from cycles to cpu-clock or task-clock on
s390 if callchains are enabled.

If frame pointer callchains are requested on s390, warn and switch to
dwarf callchains.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-record.c      |  3 ++-
 tools/perf/builtin-top.c         |  2 +-
 tools/perf/tests/event_update.c  |  4 +++-
 tools/perf/tests/expand-cgroup.c |  4 +++-
 tools/perf/tests/perf-record.c   |  7 ++++--
 tools/perf/tests/topology.c      |  4 +++-
 tools/perf/util/evlist.c         | 37 +++++++++++++++++++-------------
 tools/perf/util/evlist.h         |  2 +-
 tools/perf/util/evsel.c          | 11 ++++++++--
 9 files changed, 49 insertions(+), 25 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 60d764068302..07ecc8a5fec7 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -4310,7 +4310,8 @@ int cmd_record(int argc, const char **argv)
 		record.opts.tail_synthesize = true;
 
 	if (rec->evlist->core.nr_entries == 0) {
-		struct evlist *def_evlist = evlist__new_default();
+		struct evlist *def_evlist = evlist__new_default(&rec->opts.target,
+								callchain_param.enabled);
 
 		if (!def_evlist)
 			goto out;
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 710604c4f6f6..58bab595b024 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1695,7 +1695,7 @@ int cmd_top(int argc, const char **argv)
 		goto out_delete_evlist;
 
 	if (!top.evlist->core.nr_entries) {
-		struct evlist *def_evlist = evlist__new_default();
+		struct evlist *def_evlist = evlist__new_default(target, callchain_param.enabled);
 
 		if (!def_evlist)
 			goto out_delete_evlist;
diff --git a/tools/perf/tests/event_update.c b/tools/perf/tests/event_update.c
index cb9e6de2e033..facc65e29f20 100644
--- a/tools/perf/tests/event_update.c
+++ b/tools/perf/tests/event_update.c
@@ -8,6 +8,7 @@
 #include "header.h"
 #include "machine.h"
 #include "util/synthetic-events.h"
+#include "target.h"
 #include "tool.h"
 #include "tests.h"
 #include "debug.h"
@@ -81,7 +82,8 @@ static int test__event_update(struct test_suite *test __maybe_unused, int subtes
 {
 	struct evsel *evsel;
 	struct event_name tmp;
-	struct evlist *evlist = evlist__new_default();
+	struct target target = {};
+	struct evlist *evlist = evlist__new_default(&target, /*sample_callchains=*/false);
 
 	TEST_ASSERT_VAL("failed to get evlist", evlist);
 
diff --git a/tools/perf/tests/expand-cgroup.c b/tools/perf/tests/expand-cgroup.c
index c7b32a220ca1..dd547f2f77cc 100644
--- a/tools/perf/tests/expand-cgroup.c
+++ b/tools/perf/tests/expand-cgroup.c
@@ -8,6 +8,7 @@
 #include "parse-events.h"
 #include "pmu-events/pmu-events.h"
 #include "pfm.h"
+#include "target.h"
 #include <subcmd/parse-options.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -99,7 +100,8 @@ out:	for (i = 0; i < nr_events; i++)
 static int expand_default_events(void)
 {
 	int ret;
-	struct evlist *evlist = evlist__new_default();
+	struct target target = {};
+	struct evlist *evlist = evlist__new_default(&target, /*sample_callchains=*/false);
 
 	TEST_ASSERT_VAL("failed to get evlist", evlist);
 
diff --git a/tools/perf/tests/perf-record.c b/tools/perf/tests/perf-record.c
index efbd9cd60c63..c6e31ab8a6b8 100644
--- a/tools/perf/tests/perf-record.c
+++ b/tools/perf/tests/perf-record.c
@@ -84,8 +84,11 @@ static int test__PERF_RECORD(struct test_suite *test __maybe_unused, int subtest
 	CPU_ZERO_S(cpu_mask_size, cpu_mask);
 
 	perf_sample__init(&sample, /*all=*/false);
-	if (evlist == NULL) /* Fallback for kernels lacking PERF_COUNT_SW_DUMMY */
-		evlist = evlist__new_default();
+	if (evlist == NULL) { /* Fallback for kernels lacking PERF_COUNT_SW_DUMMY */
+		struct target target = {};
+
+		evlist = evlist__new_default(&target, /*sample_callchains=*/false);
+	}
 
 	if (evlist == NULL) {
 		pr_debug("Not enough memory to create evlist\n");
diff --git a/tools/perf/tests/topology.c b/tools/perf/tests/topology.c
index ec01150d208d..a34a7ab19a80 100644
--- a/tools/perf/tests/topology.c
+++ b/tools/perf/tests/topology.c
@@ -9,6 +9,7 @@
 #include "evlist.h"
 #include "debug.h"
 #include "pmus.h"
+#include "target.h"
 #include <linux/err.h>
 
 #define TEMPL "/tmp/perf-test-XXXXXX"
@@ -37,11 +38,12 @@ static int session_write_header(char *path)
 		.path = path,
 		.mode = PERF_DATA_MODE_WRITE,
 	};
+	struct target target = {};
 
 	session = perf_session__new(&data, NULL);
 	TEST_ASSERT_VAL("can't get session", !IS_ERR(session));
 
-	session->evlist = evlist__new_default();
+	session->evlist = evlist__new_default(&target, /*sample_callchains=*/false);
 	TEST_ASSERT_VAL("can't get evlist", session->evlist);
 	session->evlist->session = session;
 
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 591bdf0b3e2a..e6c518cc4a69 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -13,6 +13,7 @@
 #include "util/mmap.h"
 #include "thread_map.h"
 #include "target.h"
+#include "dwarf-regs.h"
 #include "evlist.h"
 #include "evsel.h"
 #include "record.h"
@@ -98,38 +99,44 @@ struct evlist *evlist__new(void)
 	return evlist;
 }
 
-struct evlist *evlist__new_default(void)
+struct evlist *evlist__new_default(const struct target *target, bool sample_callchains)
 {
 	struct evlist *evlist = evlist__new();
 	bool can_profile_kernel;
 	struct perf_pmu *pmu = NULL;
+	struct evsel *evsel;
+	char buf[256];
+	int err;
 
 	if (!evlist)
 		return NULL;
 
 	can_profile_kernel = perf_event_paranoid_check(1);
 
-	while ((pmu = perf_pmus__scan_core(pmu)) != NULL) {
-		char buf[256];
-		int err;
-
-		snprintf(buf, sizeof(buf), "%s/cycles/%s", pmu->name,
+	if (EM_HOST == EM_S390 && sample_callchains) {
+		snprintf(buf, sizeof(buf), "software/%s/%s",
+			 target__has_cpu(target) ? "cpu-clock" : "task-clock",
 			 can_profile_kernel ? "P" : "Pu");
 		err = parse_event(evlist, buf);
-		if (err) {
-			evlist__delete(evlist);
-			return NULL;
+		if (err)
+			goto out_err;
+	} else {
+		while ((pmu = perf_pmus__scan_core(pmu)) != NULL) {
+			snprintf(buf, sizeof(buf), "%s/cycles/%s", pmu->name,
+				can_profile_kernel ? "P" : "Pu");
+			err = parse_event(evlist, buf);
+			if (err)
+				goto out_err;
 		}
 	}
 
-	if (evlist->core.nr_entries > 1) {
-		struct evsel *evsel;
-
-		evlist__for_each_entry(evlist, evsel)
-			evsel__set_sample_id(evsel, /*can_sample_identifier=*/false);
-	}
+	evlist__for_each_entry(evlist, evsel)
+		evsel__set_sample_id(evsel, /*can_sample_identifier=*/false);
 
 	return evlist;
+out_err:
+	evlist__delete(evlist);
+	return NULL;
 }
 
 struct evlist *evlist__new_dummy(void)
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index d17c3b57a409..e507f5f20ef6 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -104,7 +104,7 @@ struct evsel_str_handler {
 };
 
 struct evlist *evlist__new(void);
-struct evlist *evlist__new_default(void);
+struct evlist *evlist__new_default(const struct target *target, bool sample_callchains);
 struct evlist *evlist__new_dummy(void);
 void evlist__init(struct evlist *evlist, struct perf_cpu_map *cpus,
 		  struct perf_thread_map *threads);
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index bd14d9bbc91f..caa95dc06ac5 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1020,6 +1020,13 @@ static void __evsel__config_callchain(struct evsel *evsel, struct record_opts *o
 {
 	bool function = evsel__is_function_event(evsel);
 	struct perf_event_attr *attr = &evsel->core.attr;
+	enum perf_call_graph_mode record_mode = param->record_mode;
+
+	if (EM_HOST == EM_S390 && param->record_mode == CALLCHAIN_FP) {
+		pr_warning("Framepointer unwinding switched to dwarf due to a lack of kernel support.\n"
+			   "Use '--call-graph dwarf' to silence this warning.\n");
+		record_mode = CALLCHAIN_DWARF;
+	}
 
 	evsel__set_sample_bit(evsel, CALLCHAIN);
 
@@ -1029,7 +1036,7 @@ static void __evsel__config_callchain(struct evsel *evsel, struct record_opts *o
 		attr->exclude_callchain_user = 1;
 	if (opts->user_callchains)
 		attr->exclude_callchain_kernel = 1;
-	if (param->record_mode == CALLCHAIN_LBR) {
+	if (record_mode == CALLCHAIN_LBR) {
 		if (!opts->branch_stack) {
 			if (attr->exclude_user) {
 				pr_warning("LBR callstack option is only available "
@@ -1048,7 +1055,7 @@ static void __evsel__config_callchain(struct evsel *evsel, struct record_opts *o
 				    "Falling back to framepointers.\n");
 	}
 
-	if (param->record_mode == CALLCHAIN_DWARF) {
+	if (record_mode == CALLCHAIN_DWARF) {
 		if (!function) {
 			uint16_t e_machine = evsel__e_machine(evsel, /*e_flags=*/NULL);
 
-- 
2.53.0.851.ga537e3e6e9-goog