generic, x86: add prctl commands PR_GET_TSC and PR_SET_TSC

This patch adds prctl commands that make it possible
to deny the execution of timestamp counters in userspace.
If this is not implemented on a specific architecture,
prctl will return -EINVAL.

ned-off-by: Erik Bosman <ejbosman@cs.vu.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/sys.c b/kernel/sys.c
index a626116..6a0cc71 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -67,6 +67,12 @@
 #ifndef SET_ENDIAN
 # define SET_ENDIAN(a,b)	(-EINVAL)
 #endif
+#ifndef GET_TSC_CTL
+# define GET_TSC_CTL(a)		(-EINVAL)
+#endif
+#ifndef SET_TSC_CTL
+# define SET_TSC_CTL(a)		(-EINVAL)
+#endif
 
 /*
  * this is where the system-wide overflow UID and GID are defined, for
@@ -1737,7 +1743,12 @@
 #else
 			return -EINVAL;
 #endif
-
+		case PR_GET_TSC:
+			error = GET_TSC_CTL(arg2);
+			break;
+		case PR_SET_TSC:
+			error = SET_TSC_CTL(arg2);
+			break;
 		default:
 			error = -EINVAL;
 			break;