libperf: Add 'event_copy' to 'struct perf_mmap'

Move 'event_copy' from tools/perf's mmap to libperf's perf_mmap struct.

Committer notes:

Add linux/compiler.h as we need it for '__aligned'.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lore.kernel.org/lkml/20190913132355.21634-18-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/lib/include/internal/mmap.h

@@ -2,10 +2,14 @@
 #ifndef __LIBPERF_INTERNAL_MMAP_H
 #define __LIBPERF_INTERNAL_MMAP_H
 
+#include <linux/compiler.h>
 #include <linux/refcount.h>
 #include <linux/types.h>
 #include <stdbool.h>
 
+/* perf sample has 16 bits size limit */
+#define PERF_SAMPLE_MAX_SIZE (1 << 16)
+
 /**
  * struct perf_mmap - perf's ring buffer mmap details
  *
@@ -21,6 +25,7 @@ struct perf_mmap {
 	u64		 start;
 	u64		 end;
 	bool		 overwrite;
+	char		 event_copy[PERF_SAMPLE_MAX_SIZE] __aligned(8);
 };
 
 #endif /* __LIBPERF_INTERNAL_MMAP_H */

tools/perf/util/mmap.c

@@ -51,7 +51,7 @@ static union perf_event *perf_mmap__read(struct mmap *map,
 		if ((*startp & map->core.mask) + size != ((*startp + size) & map->core.mask)) {
 			unsigned int offset = *startp;
 			unsigned int len = min(sizeof(*event), size), cpy;
-			void *dst = map->event_copy;
+			void *dst = map->core.event_copy;
 
 			do {
 				cpy = min(map->core.mask + 1 - (offset & map->core.mask), len);
@@ -61,7 +61,7 @@ static union perf_event *perf_mmap__read(struct mmap *map,
 				len -= cpy;
 			} while (len);
 
-			event = (union perf_event *)map->event_copy;
+			event = (union perf_event *)map->core.event_copy;
 		}
 
 		*startp += size;

tools/perf/util/mmap.h

@@ -23,7 +23,6 @@ struct aiocb;
 struct mmap {
 	struct perf_mmap	core;
 	struct auxtrace_mmap auxtrace_mmap;
-	char		 event_copy[PERF_SAMPLE_MAX_SIZE] __aligned(8);
 #ifdef HAVE_AIO_SUPPORT
 	struct {
 		void		 **data;