perf test pmu-events: Fake PMU metric workaround

We test metrics with fake events with fake values. The fake values may
yield division by zero and so we count both up and down to try to
avoid this. Unfortunately this isn't sufficient for some metrics and
so don't fail the test for them.

Add the metric name to debug output.

Signed-off-by: Ian Rogers <[e-mail]>
Acked-by: Kan Liang <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Caleb Biggers <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: John Garry <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Perry Taylor <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Stephane Eranian <[e-mail]>
Cc: Xing Zhengjun <[e-mail]>
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/pmu-events.c

···
 	{ "(imx8_ddr0@read\\-cycles@ + imx8_ddr0@write\\-cycles@)", },
 };
 
-static int metric_parse_fake(const char *str)
+static int metric_parse_fake(const char *metric_name, const char *str)
 {
 	struct expr_parse_ctx *ctx;
 	struct hashmap_entry *cur;
···
 	size_t bkt;
 	int i;
 
-	pr_debug("parsing '%s'\n", str);
+	pr_debug("parsing '%s': '%s'\n", metric_name, str);
 
 	ctx = expr__ctx_new();
 	if (!ctx) {
···
 		hashmap__for_each_entry(ctx->ids, cur, bkt)
 			expr__add_id_val(ctx, strdup(cur->pkey), i--);
 		if (expr__parse(&result, ctx, str)) {
-			pr_err("expr__parse failed\n");
-			ret = -1;
+			pr_err("expr__parse failed for %s\n", metric_name);
+			/* The following have hard to avoid divide by zero. */
+			if (!strcmp(metric_name, "tma_clears_resteers") ||
+			    !strcmp(metric_name, "tma_mispredicts_resteers"))
+				ret = 0;
+			else
+				ret = -1;
 		}
 	}
 
···
 	if (!pe->metric_expr)
 		return 0;
 
-	return metric_parse_fake(pe->metric_expr);
+	return metric_parse_fake(pe->metric_name, pe->metric_expr);
 }
 
 /*
···
 	int err = 0;
 
 	for (size_t i = 0; i < ARRAY_SIZE(metrics); i++) {
-		err = metric_parse_fake(metrics[i].str);
+		err = metric_parse_fake("", metrics[i].str);
 		if (err)
 			return err;
 	}