perf pmu: When using default config, record which bits of config were changed by the user

Default config for a PMU is defined before selected events are parsed.
That allows the user-entered config to override the default config.

However that does not allow for changing the default config based on
other options.

For example, if the user chooses AUX area sampling mode, in the case of
Intel PT, the psb_period needs to be small for sampling, so there is a
need to set the default psb_period to 0 (2 KiB) in that case. However
that should not override a value set by the user. To allow for that,
when using default config, record which bits of config were changed by
the user.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20191115124225.5247-13-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 41 insertions, 1 deletions

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index fc5e27bc8315..6c313c4087ed 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1290,7 +1290,40 @@ do {								\
 			break;
 		}
 	}
-#undef ADD_EVSEL_CONFIG
+	return 0;
+}
+
+/*
+ * Add PERF_EVSEL__CONFIG_TERM_CFG_CHG where cfg_chg will have a bit set for
+ * each bit of attr->config that the user has changed.
+ */
+static int get_config_chgs(struct perf_pmu *pmu, struct list_head *head_config,
+			   struct list_head *head_terms)
+{
+	struct parse_events_term *term;
+	u64 bits = 0;
+	int type;
+
+	list_for_each_entry(term, head_config, list) {
+		switch (term->type_term) {
+		case PARSE_EVENTS__TERM_TYPE_USER:
+			type = perf_pmu__format_type(&pmu->format, term->config);
+			if (type != PERF_PMU_FORMAT_VALUE_CONFIG)
+				continue;
+			bits |= perf_pmu__format_bits(&pmu->format, term->config);
+			break;
+		case PARSE_EVENTS__TERM_TYPE_CONFIG:
+			bits = ~(u64)0;
+			break;
+		default:
+			break;
+		}
+	}
+
+	if (bits)
+		ADD_CONFIG_TERM(CFG_CHG, cfg_chg, bits);
+
+#undef ADD_CONFIG_TERM
 	return 0;
 }
 
@@ -1419,6 +1452,13 @@ int parse_events_add_pmu(struct parse_events_state *parse_state,
 	if (get_config_terms(head_config, &config_terms))
 		return -ENOMEM;
 
+	/*
+	 * When using default config, record which bits of attr->config were
+	 * changed by the user.
+	 */
+	if (pmu->default_config && get_config_chgs(pmu, head_config, &config_terms))
+		return -ENOMEM;
+
 	if (perf_pmu__config(pmu, &attr, head_config, parse_state->error)) {
 		struct perf_evsel_config_term *pos, *tmp;