[tip:perf/core] perf auxtrace: Define auxtrace record alignment

[tip-bot for Adrian Hunter <tipbot@zytor.com>]

Commit-ID:  c3fcadf0bb765faf45d6d562246e1d08885466df
Gitweb:     https://git.kernel.org/tip/c3fcadf0bb765faf45d6d562246e1d08885466df
Author:     Adrian Hunter <adrian.hunter@intel.com>
AuthorDate: Wed, 6 Feb 2019 12:39:43 +0200
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 6 Feb 2019 10:25:39 -0300

perf auxtrace: Define auxtrace record alignment

Define auxtrace record alignment so that it can be referenced elsewhere.

Note this is preparation for patch "perf intel-pt: Fix overlap calculation
for padding"

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20190206103947.15750-2-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/auxtrace.c | 4 ++--
 tools/perf/util/auxtrace.h | 3 +++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index 94a22cc8004c..ad186d3255d1 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -1279,9 +1279,9 @@ static int __auxtrace_mmap__read(struct perf_mmap *map,
 	}
 
 	/* padding must be written by fn() e.g. record__process_auxtrace() */
-	padding = size & 7;
+	padding = size & (PERF_AUXTRACE_RECORD_ALIGNMENT - 1);
 	if (padding)
-		padding = 8 - padding;
+		padding = PERF_AUXTRACE_RECORD_ALIGNMENT - padding;
 
 	memset(&ev, 0, sizeof(ev));
 	ev.auxtrace.header.type = PERF_RECORD_AUXTRACE;
diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
index 8e50f96d4b23..fac32482db61 100644
--- a/tools/perf/util/auxtrace.h
+++ b/tools/perf/util/auxtrace.h
@@ -40,6 +40,9 @@ struct record_opts;
 struct auxtrace_info_event;
 struct events_stats;
 
+/* Auxtrace records must have the same alignment as perf event records */
+#define PERF_AUXTRACE_RECORD_ALIGNMENT 8
+
 enum auxtrace_type {
 	PERF_AUXTRACE_UNKNOWN,
 	PERF_AUXTRACE_INTEL_PT,