perf auxtrace: Allow buffers to be mapped read / write

To support in-place update, allow buffers to be mapped read / write.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20210430070309.17624-7-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/auxtrace.c

@@ -1120,8 +1120,9 @@ int auxtrace_queue_data(struct perf_session *session, bool samples, bool events)
 					 auxtrace_queue_data_cb, &qd);
 }
 
-void *auxtrace_buffer__get_data(struct auxtrace_buffer *buffer, int fd)
+void *auxtrace_buffer__get_data_rw(struct auxtrace_buffer *buffer, int fd, bool rw)
 {
+	int prot = rw ? PROT_READ | PROT_WRITE : PROT_READ;
 	size_t adj = buffer->data_offset & (page_size - 1);
 	size_t size = buffer->size + adj;
 	off_t file_offset = buffer->data_offset - adj;
@@ -1130,7 +1131,7 @@ void *auxtrace_buffer__get_data(struct auxtrace_buffer *buffer, int fd)
 	if (buffer->data)
 		return buffer->data;
 
-	addr = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, file_offset);
+	addr = mmap(NULL, size, prot, MAP_SHARED, fd, file_offset);
 	if (addr == MAP_FAILED)
 		return NULL;
 

tools/perf/util/auxtrace.h

@@ -533,7 +533,11 @@ int auxtrace_queue_data(struct perf_session *session, bool samples,
 			bool events);
 struct auxtrace_buffer *auxtrace_buffer__next(struct auxtrace_queue *queue,
 					      struct auxtrace_buffer *buffer);
-void *auxtrace_buffer__get_data(struct auxtrace_buffer *buffer, int fd);
+void *auxtrace_buffer__get_data_rw(struct auxtrace_buffer *buffer, int fd, bool rw);
+static inline void *auxtrace_buffer__get_data(struct auxtrace_buffer *buffer, int fd)
+{
+	return auxtrace_buffer__get_data_rw(buffer, fd, false);
+}
 void auxtrace_buffer__put_data(struct auxtrace_buffer *buffer);
 void auxtrace_buffer__drop_data(struct auxtrace_buffer *buffer);
 void auxtrace_buffer__free(struct auxtrace_buffer *buffer);