perf pmu: Improve error messages for missing PMUs

When a PMU is missing print a better error message mentioning
the missing PMU.

% mkdir empty
% mount --bind empty /sys/devices/msr
% perf stat -M Summary true
event syntax error: '{inst_retired.any,cycles}:W,{cpu_clk_unhalted.thread}:W,{inst_retired.any}:W,{cpu_clk_unhalted.ref_tsc,msr/tsc/}:W,{fp_comp_ops_exe.sse_scalar..'
                     \___ Cannot find PMU `msr'. Missing kernel support?

It still cannot find the right column for aliases, but it's already a vast improvement.

v2: Check asprintf

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20170913215006.32222-1-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/metricgroup.c

@@ -477,7 +477,7 @@ int metricgroup__parse_groups(const struct option *opt,
 	memset(&parse_error, 0, sizeof(struct parse_events_error));
 	ret = parse_events(perf_evlist, extra_events.buf, &parse_error);
 	if (ret) {
-		pr_err("Cannot set up events %s\n", extra_events.buf);
+		parse_events_print_error(&parse_error, extra_events.buf);
 		goto out;
 	}
 	strbuf_release(&extra_events);

tools/perf/util/parse-events.c

@@ -1219,11 +1219,17 @@ static int __parse_events_add_pmu(struct parse_events_state *parse_state,
 	struct perf_pmu_info info;
 	struct perf_pmu *pmu;
 	struct perf_evsel *evsel;
+	struct parse_events_error *err = parse_state->error;
 	LIST_HEAD(config_terms);
 
 	pmu = perf_pmu__find(name);
-	if (!pmu)
+	if (!pmu) {
+		if (asprintf(&err->str,
+				"Cannot find PMU `%s'. Missing kernel support?",
+				name) < 0)
+			err->str = NULL;
 		return -EINVAL;
+	}
 
 	if (pmu->default_config) {
 		memcpy(&attr, pmu->default_config,
@@ -1733,8 +1739,8 @@ static int get_term_width(void)
 	return ws.ws_col > MAX_WIDTH ? MAX_WIDTH : ws.ws_col;
 }
 
-static void parse_events_print_error(struct parse_events_error *err,
-				     const char *event)
+void parse_events_print_error(struct parse_events_error *err,
+			      const char *event)
 {
 	const char *str = "invalid or unsupported event: ";
 	char _buf[MAX_WIDTH];
@@ -1789,8 +1795,6 @@ static void parse_events_print_error(struct parse_events_error *err,
 		zfree(&err->str);
 		zfree(&err->help);
 	}
-
-	fprintf(stderr, "Run 'perf list' for a list of valid events\n");
 }
 
 #undef MAX_WIDTH
@@ -1802,8 +1806,10 @@ int parse_events_option(const struct option *opt, const char *str,
 	struct parse_events_error err = { .idx = 0, };
 	int ret = parse_events(evlist, str, &err);
 
-	if (ret)
+	if (ret) {
 		parse_events_print_error(&err, str);
+		fprintf(stderr, "Run 'perf list' for a list of valid events\n");
+	}
 
 	return ret;
 }

tools/perf/util/parse-events.h

@@ -202,6 +202,9 @@ int is_valid_tracepoint(const char *event_string);
 int valid_event_mount(const char *eventfs);
 char *parse_events_formats_error_string(char *additional_terms);
 
+void parse_events_print_error(struct parse_events_error *err,
+			      const char *event);
+
 #ifdef HAVE_LIBELF_SUPPORT
 /*
  * If the probe point starts with '%',