[PATCH 12/15] perf pmu: When using default config, record which bits of config were changed by the user

[Adrian Hunter]

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@xxxxxxxxx>
---
 tools/perf/util/evsel.c        |  2 ++
 tools/perf/util/evsel_config.h |  2 ++
 tools/perf/util/parse-events.c | 42 +++++++++++++++++++++++++++++++++-
 tools/perf/util/pmu.c          | 10 ++++++++
 tools/perf/util/pmu.h          |  1 +
 5 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index ad7665a546cf..f4dea055b080 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -849,6 +849,8 @@ static void apply_config_terms(struct evsel *evsel,
 		case PERF_EVSEL__CONFIG_TERM_AUX_SAMPLE_SIZE:
 			/* Already applied by auxtrace */
 			break;
+		case PERF_EVSEL__CONFIG_TERM_CFG_CHG:
+			break;
 		default:
 			break;
 		}
diff --git a/tools/perf/util/evsel_config.h b/tools/perf/util/evsel_config.h
index 6e654ede8fbe..1f8d2fe0b66e 100644
--- a/tools/perf/util/evsel_config.h
+++ b/tools/perf/util/evsel_config.h
@@ -26,6 +26,7 @@ enum evsel_term_type {
 	PERF_EVSEL__CONFIG_TERM_PERCORE,
 	PERF_EVSEL__CONFIG_TERM_AUX_OUTPUT,
 	PERF_EVSEL__CONFIG_TERM_AUX_SAMPLE_SIZE,
+	PERF_EVSEL__CONFIG_TERM_CFG_CHG,
 };
 
 struct perf_evsel_config_term {
@@ -46,6 +47,7 @@ struct perf_evsel_config_term {
 		bool	      percore;
 		bool	      aux_output;
 		u32	      aux_sample_size;
+		u64	      cfg_chg;
 	} val;
 	bool weak;
 };
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 73e0bf293c12..c825020db402 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1273,7 +1273,40 @@ 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;
 }
 
@@ -1402,6 +1435,13 @@ 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;
 
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index db1e57113f4b..e8d348988026 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -931,6 +931,16 @@ __u64 perf_pmu__format_bits(struct list_head *formats, const char *name)
 	return bits;
 }
 
+int perf_pmu__format_type(struct list_head *formats, const char *name)
+{
+	struct perf_pmu_format *format = pmu_find_format(formats, name);
+
+	if (!format)
+		return -1;
+
+	return format->value;
+}
+
 /*
  * Sets value based on the format definition (format parameter)
  * and unformated value (value parameter).
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 2eb7a7001307..6737e3d5d568 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -72,6 +72,7 @@ int perf_pmu__config_terms(struct list_head *formats,
 			   struct list_head *head_terms,
 			   bool zero, struct parse_events_error *error);
 __u64 perf_pmu__format_bits(struct list_head *formats, const char *name);
+int perf_pmu__format_type(struct list_head *formats, const char *name);
 int perf_pmu__check_alias(struct perf_pmu *pmu, struct list_head *head_terms,
 			  struct perf_pmu_info *info);
 struct list_head *perf_pmu__alias(struct perf_pmu *pmu,
-- 
2.17.1