perf tools: Check mmap pages value early

Move the check of the mmap_pages value to the options parsing time, so
we could rely on this value on other parts of code.

Related changes come in the next patches.

Also changes perf_evlist::mmap_len to proper size_t type.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1378031796-17892-2-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index 935d522..cfa0b79 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -1426,8 +1426,9 @@
 	const struct option live_options[] = {
 		OPT_STRING('p', "pid", &kvm->opts.target.pid, "pid",
 			"record events on existing process id"),
-		OPT_UINTEGER('m', "mmap-pages", &kvm->opts.mmap_pages,
-			"number of mmap data pages"),
+		OPT_CALLBACK('m', "mmap-pages", &kvm->opts.mmap_pages, "pages",
+			"number of mmap data pages",
+			perf_evlist__parse_mmap_pages),
 		OPT_INCR('v', "verbose", &verbose,
 			"be more verbose (show counter open errors, etc)"),
 		OPT_BOOLEAN('a', "all-cpus", &kvm->opts.target.system_wide,