perf symbols: Fix up map end too on modular kernels with no modules installed

In 2161db9 we stopped failing when not finding modules when
asked too, but then the kernel maps (just one, for vmlinux)
wasn't having its ->end field correctly set up, so symbols were
not being found for the vmlinux map because its range was 0-0.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1266702793-29434-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/util/event.c

@@ -379,6 +379,12 @@ int event__process_mmap(event_t *self, struct perf_session *session)
 
 			session->vmlinux_maps[MAP__FUNCTION]->start = self->mmap.start;
 			session->vmlinux_maps[MAP__FUNCTION]->end   = self->mmap.start + self->mmap.len;
+			/*
+			 * Be a bit paranoid here, some perf.data file came with
+			 * a zero sized synthesized MMAP event for the kernel.
+			 */
+			if (session->vmlinux_maps[MAP__FUNCTION]->end == 0)
+				session->vmlinux_maps[MAP__FUNCTION]->end = ~0UL;
 
 			perf_session__set_kallsyms_ref_reloc_sym(session, symbol_name,
 								 self->mmap.pgoff);

tools/perf/util/symbol.c

@@ -1937,7 +1937,7 @@ int map_groups__create_kernel_maps(struct map_groups *self,
 		return -1;
 
 	if (symbol_conf.use_modules && map_groups__create_modules(self) < 0)
-		return 0;
+		pr_debug("Problems creating module maps, continuing anyway...\n");
 	/*
 	 * Now that we have all the maps created, just set the ->end of them:
 	 */