perf symbols: Check if a struct machine instance was found

Which can happen when processing old files that had no fake kernel MMAP,
events.

That shouldn't result in perf_session__create_kernel_maps not being
called, this will be fixed in a followup patch, for now do these checks
to avoid segfaulting.

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>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 46563e16c3f5..dfc8bf64d70f 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -493,8 +493,10 @@ int event__process_mmap(event_t *self, struct perf_session *session)
                 return 0;
         }
 
-        thread = perf_session__findnew(session, self->mmap.pid);
         machine = perf_session__find_host_machine(session);
+        if (machine == NULL)
+                goto out_problem;
+        thread = perf_session__findnew(session, self->mmap.pid);
         map = map__new(&machine->user_dsos, self->mmap.start,
                         self->mmap.len, self->mmap.pgoff,
                         self->mmap.pid, self->mmap.filename,
@@ -552,6 +554,10 @@ void thread__find_addr_map(struct thread *self,
         if (cpumode == PERF_RECORD_MISC_KERNEL && perf_host) {
                 al->level = 'k';
                 machine = perf_session__find_host_machine(session);
+                if (machine == NULL) {
+                        al->map = NULL;
+                        return;
+                }
                 mg = &machine->kmaps;
         } else if (cpumode == PERF_RECORD_MISC_USER && perf_host) {
                 al->level = '.';
@@ -559,7 +565,7 @@ void thread__find_addr_map(struct thread *self,
         } else if (cpumode == PERF_RECORD_MISC_GUEST_KERNEL && perf_guest) {
                 al->level = 'g';
                 machine = perf_session__find_machine(session, pid);
-                if (!machine) {
+                if (machine == NULL) {
                         al->map = NULL;
                         return;
                 }