perf: Use sample_flags for txn

Use the new sample_flags to indicate whether the txn field is filled by
the PMU driver.

Remove the txn field from the perf_sample_data_init() to minimize the
number of cache lines touched.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220901130959.1285717-7-kan.liang@linux.intel.com

arch/x86/events/intel/ds.c

@@ -1628,9 +1628,11 @@ static void setup_pebs_fixed_sample_data(struct perf_event *event,
 			data->weight.full = intel_get_tsx_weight(pebs->tsx_tuning);
 			data->sample_flags |= PERF_SAMPLE_WEIGHT_TYPE;
 		}
-		if (sample_type & PERF_SAMPLE_TRANSACTION)
+		if (sample_type & PERF_SAMPLE_TRANSACTION) {
 			data->txn = intel_get_tsx_transaction(pebs->tsx_tuning,
 							      pebs->ax);
+			data->sample_flags |= PERF_SAMPLE_TRANSACTION;
+		}
 	}
 
 	/*
@@ -1780,9 +1782,11 @@ static void setup_pebs_adaptive_sample_data(struct perf_event *event,
 		if (sample_type & PERF_SAMPLE_ADDR_TYPE)
 			data->addr = meminfo->address;
 
-		if (sample_type & PERF_SAMPLE_TRANSACTION)
+		if (sample_type & PERF_SAMPLE_TRANSACTION) {
 			data->txn = intel_get_tsx_transaction(meminfo->tsx_tuning,
 							  gprs ? gprs->ax : 0);
+			data->sample_flags |= PERF_SAMPLE_TRANSACTION;
+		}
 	}
 
 	if (format_size & PEBS_DATACFG_XMMS) {

include/linux/perf_event.h

@@ -1012,7 +1012,6 @@ struct perf_sample_data {
 	u64				addr;
 	struct perf_raw_record		*raw;
 	u64				period;
-	u64				txn;
 
 	/*
 	 * The other fields, optionally {set,used} by
@@ -1021,6 +1020,7 @@ struct perf_sample_data {
 	struct perf_branch_stack	*br_stack;
 	union perf_sample_weight	weight;
 	union  perf_mem_data_src	data_src;
+	u64				txn;
 
 	u64				type;
 	u64				ip;
@@ -1063,7 +1063,6 @@ static inline void perf_sample_data_init(struct perf_sample_data *data,
 	data->addr = addr;
 	data->raw  = NULL;
 	data->period = period;
-	data->txn = 0;
 }
 
 /*

kernel/events/core.c

@@ -7414,6 +7414,9 @@ void perf_prepare_sample(struct perf_event_header *header,
 	if (filtered_sample_type & PERF_SAMPLE_DATA_SRC)
 		data->data_src.val = PERF_MEM_NA;
 
+	if (filtered_sample_type & PERF_SAMPLE_TRANSACTION)
+		data->txn = 0;
+
 	if (sample_type & PERF_SAMPLE_REGS_INTR) {
 		/* regs dump ABI info */
 		int size = sizeof(u64);