perf/x86: Add flags to event constraints

This patch adds a flags field to each event constraint.
It can be used to store event specific features which can
then later be used by scheduling code or low-level x86 code.

The flags are propagated into event->hw.flags during the
get_event_constraint() call. They are cleared during the
put_event_constraint() call.

This mechanism is going to be used by the PEBS-LL patches.
It avoids defining yet another table to hold event specific
information.

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: peterz@infradead.org
Cc: ak@linux.intel.com
Cc: jolsa@redhat.com
Cc: namhyung.kim@lge.com
Link: http://lkml.kernel.org/r/1359040242-8269-4-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 1c59211..cd3bb2c 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -127,6 +127,7 @@
 			int		event_base_rdpmc;
 			int		idx;
 			int		last_cpu;
+			int		flags;
 
 			struct hw_perf_event_extra extra_reg;
 			struct hw_perf_event_extra branch_reg;