perf evlist: Add can_select_event() method

Add a function to determine whether an event can be selected.

This function is needed to allow a tool to automatically select
additional events, but only if they are available.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1386765443-26966-18-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 39 insertions, 0 deletions

diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 649d6ea98a84..8a04aae95a18 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -193,4 +193,6 @@ static inline void perf_mmap__write_tail(struct perf_mmap *md,
         pc->data_tail = tail;
 }
 
+bool perf_evlist__can_select_event(struct perf_evlist *evlist, const char *str);
+
 #endif /* __PERF_EVLIST_H */
diff --git a/tools/perf/util/record.c b/tools/perf/util/record.c
index c8845b107f60..e5104538c354 100644
--- a/tools/perf/util/record.c
+++ b/tools/perf/util/record.c
@@ -177,3 +177,40 @@ int perf_record_opts__config(struct perf_record_opts *opts)
 {
         return perf_record_opts__config_freq(opts);
 }
+
+bool perf_evlist__can_select_event(struct perf_evlist *evlist, const char *str)
+{
+        struct perf_evlist *temp_evlist;
+        struct perf_evsel *evsel;
+        int err, fd, cpu;
+        bool ret = false;
+
+        temp_evlist = perf_evlist__new();
+        if (!temp_evlist)
+                return false;
+
+        err = parse_events(temp_evlist, str);
+        if (err)
+                goto out_delete;
+
+        evsel = perf_evlist__last(temp_evlist);
+
+        if (!evlist || cpu_map__empty(evlist->cpus)) {
+                struct cpu_map *cpus = cpu_map__new(NULL);
+
+                cpu =  cpus ? cpus->map[0] : 0;
+                cpu_map__delete(cpus);
+        } else {
+                cpu = evlist->cpus->map[0];
+        }
+
+        fd = sys_perf_event_open(&evsel->attr, -1, cpu, -1, 0);
+        if (fd >= 0) {
+                close(fd);
+                ret = true;
+        }
+
+out_delete:
+        perf_evlist__delete(temp_evlist);
+        return ret;
+}