perf tools: Support PERF_SAMPLE_WEIGHT_STRUCT

The new sample type, PERF_SAMPLE_WEIGHT_STRUCT, is an alternative of the
PERF_SAMPLE_WEIGHT sample type. Users can apply either the
PERF_SAMPLE_WEIGHT sample type or the PERF_SAMPLE_WEIGHT_STRUCT sample
type to retrieve the sample weight, but they cannot apply both sample
types simultaneously.

The new sample type shares the same space as the PERF_SAMPLE_WEIGHT
sample type. The lower 32 bits are exactly the same for both sample
type. The higher 32 bits may be different for different architecture.

Add arch specific arch_evsel__set_sample_weight() to set the new sample
type for X86. Only store the lower 32 bits for the sample->weight if the
new sample type is applied. In practice, no memory access could last
than 4G cycles. No data will be lost.

If the kernel doesn't support the new sample type. Fall back to the
PERF_SAMPLE_WEIGHT sample type.

There is no impact for other architectures.

Committer notes:

Fixup related to PERF_SAMPLE_CODE_PAGE_SIZE, present in acme/perf/core
but not upstream yet.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/1612296553-21962-6-git-send-email-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index fcec775636ac..4e9266f75175 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1468,7 +1468,7 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
 		}
 	}
 
-	if (type & PERF_SAMPLE_WEIGHT)
+	if (type & PERF_SAMPLE_WEIGHT_TYPE)
 		result += sizeof(u64);
 
 	if (type & PERF_SAMPLE_DATA_SRC)
@@ -1642,8 +1642,10 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
 		}
 	}
 
-	if (type & PERF_SAMPLE_WEIGHT) {
+	if (type & PERF_SAMPLE_WEIGHT_TYPE) {
 		*array = sample->weight;
+		if (type & PERF_SAMPLE_WEIGHT_STRUCT)
+			*array &= 0xffffffff;
 		array++;
 	}