perf session: Embed the host machine data on perf_session

We have just one host on a given session, and that is the most common
setup right now, so embed a ->host_machine struct machine instance
directly in the perf_session class, check if we're looking for it before
going to the rb_tree.

This also fixes a problem found when we try to process old perf.data
files where we didn't have MMAP events for the kernel and modules and
thus don't create the kernel maps, do it in event__preprocess_sample if
it wasn't already.

Reported-by: Ingo Molnar <mingo@elte.hu>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Zhang, Yanmin <yanmin_zhang@linux.intel.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 5d353e7..71bc608 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -100,6 +100,7 @@
 	self->repipe = repipe;
 	self->ordered_samples.flush_limit = ULLONG_MAX;
 	INIT_LIST_HEAD(&self->ordered_samples.samples_head);
+	machine__init(&self->host_machine, "", HOST_KERNEL_ID);
 
 	if (mode == O_RDONLY) {
 		if (perf_session__open(self, force) < 0)
@@ -870,3 +871,10 @@
 
 	return 0;
 }
+
+size_t perf_session__fprintf_dsos(struct perf_session *self, FILE *fp)
+{
+	return __dsos__fprintf(&self->host_machine.kernel_dsos, fp) +
+	       __dsos__fprintf(&self->host_machine.user_dsos, fp) +
+	       machines__fprintf_dsos(&self->machines, fp);
+}