perf tools: Add util function for overriding user set config values

There is some duplicated code to only override config values if they
haven't already been set by the user so make a util function for this.

Signed-off-by: James Clark <james.clark@arm.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Denis Nikitin <denik@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20230424134748.228137-3-james.clark@arm.com
[ Moved evsel__set_config_if_unset() to util/pmu.c to avoid dragging stuff into the python binding ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Author: James-A-Clark

tools/perf/arch/arm64/util/arm-spe.c

@@ -36,29 +36,6 @@ struct arm_spe_recording {
 	bool			*wrapped;
 };
 
-static void arm_spe_set_timestamp(struct auxtrace_record *itr,
-				  struct evsel *evsel)
-{
-	struct arm_spe_recording *ptr;
-	struct perf_pmu *arm_spe_pmu;
-	struct evsel_config_term *term = evsel__get_config_term(evsel, CFG_CHG);
-	u64 user_bits = 0, bit;
-
-	ptr = container_of(itr, struct arm_spe_recording, itr);
-	arm_spe_pmu = ptr->arm_spe_pmu;
-
-	if (term)
-		user_bits = term->val.cfg_chg;
-
-	bit = perf_pmu__format_bits(&arm_spe_pmu->format, "ts_enable");
-
-	/* Skip if user has set it */
-	if (bit & user_bits)
-		return;
-
-	evsel->core.attr.config |= bit;
-}
-
 static size_t
 arm_spe_info_priv_size(struct auxtrace_record *itr __maybe_unused,
 		       struct evlist *evlist __maybe_unused)
@@ -238,7 +215,8 @@ static int arm_spe_recording_options(struct auxtrace_record *itr,
 	 */
 	if (!perf_cpu_map__empty(cpus)) {
 		evsel__set_sample_bit(arm_spe_evsel, CPU);
-		arm_spe_set_timestamp(itr, arm_spe_evsel);
+		evsel__set_config_if_unset(arm_spe_pmu, arm_spe_evsel,
+					   "ts_enable", 1);
 	}
 
 	/*

tools/perf/arch/x86/util/intel-pt.c

@@ -576,25 +576,6 @@ static int intel_pt_validate_config(struct perf_pmu *intel_pt_pmu,
 	return err;
 }
 
-static void intel_pt_config_sample_mode(struct perf_pmu *intel_pt_pmu,
-					struct evsel *evsel)
-{
-	u64 user_bits = 0, bits;
-	struct evsel_config_term *term = evsel__get_config_term(evsel, CFG_CHG);
-
-	if (term)
-		user_bits = term->val.cfg_chg;
-
-	bits = perf_pmu__format_bits(&intel_pt_pmu->format, "psb_period");
-
-	/* Did user change psb_period */
-	if (bits & user_bits)
-		return;
-
-	/* Set psb_period to 0 */
-	evsel->core.attr.config &= ~bits;
-}
-
 static void intel_pt_min_max_sample_sz(struct evlist *evlist,
 				       size_t *min_sz, size_t *max_sz)
 {
@@ -686,7 +667,8 @@ static int intel_pt_recording_options(struct auxtrace_record *itr,
 		return 0;
 
 	if (opts->auxtrace_sample_mode)
-		intel_pt_config_sample_mode(intel_pt_pmu, intel_pt_evsel);
+		evsel__set_config_if_unset(intel_pt_pmu, intel_pt_evsel,
+					   "psb_period", 0);
 
 	err = intel_pt_validate_config(intel_pt_pmu, intel_pt_evsel);
 	if (err)

tools/perf/util/evsel.h

@@ -530,4 +530,7 @@ bool arch_evsel__must_be_in_group(const struct evsel *evsel);
 	((((src) >> (pos)) & ((1ull << (size)) - 1)) << (63 - ((pos) + (size) - 1)))
 
 u64 evsel__bitfield_swap_branch_flags(u64 value);
+void evsel__set_config_if_unset(struct perf_pmu *pmu, struct evsel *evsel,
+				const char *config_name, u64 val);
+
 #endif /* __PERF_EVSEL_H */

tools/perf/util/pmu.c

@@ -33,6 +33,7 @@
 #include "strbuf.h"
 #include "fncache.h"
 #include "pmu-hybrid.h"
+#include "util/evsel_config.h"
 
 struct perf_pmu perf_pmu__fake;
 
@@ -1056,6 +1057,35 @@ bool evsel__is_aux_event(const struct evsel *evsel)
 	return pmu && pmu->auxtrace;
 }
 
+/*
+ * Set @config_name to @val as long as the user hasn't already set or cleared it
+ * by passing a config term on the command line.
+ *
+ * @val is the value to put into the bits specified by @config_name rather than
+ * the bit pattern. It is shifted into position by this function, so to set
+ * something to true, pass 1 for val rather than a pre shifted value.
+ */
+#define field_prep(_mask, _val) (((_val) << (ffsll(_mask) - 1)) & (_mask))
+void evsel__set_config_if_unset(struct perf_pmu *pmu, struct evsel *evsel,
+				const char *config_name, u64 val)
+{
+	u64 user_bits = 0, bits;
+	struct evsel_config_term *term = evsel__get_config_term(evsel, CFG_CHG);
+
+	if (term)
+		user_bits = term->val.cfg_chg;
+
+	bits = perf_pmu__format_bits(&pmu->format, config_name);
+
+	/* Do nothing if the user changed the value */
+	if (bits & user_bits)
+		return;
+
+	/* Otherwise replace it */
+	evsel->core.attr.config &= ~bits;
+	evsel->core.attr.config |= field_prep(bits, val);
+}
+
 struct perf_pmu *perf_pmu__find(const char *name)
 {
 	struct perf_pmu *pmu;