Add get_control_page() library function

2 files changed, 20 insertions, 0 deletions

diff --git a/include/litmus.h b/include/litmus.h
index 6d0ad40..e0f16d3 100644
--- a/include/litmus.h
+++ b/include/litmus.h
@@ -120,6 +120,13 @@ static inline int open_srp_sem(int fd, int name)
 /* syscall overhead measuring */
 int null_call(cycles_t *timestamp);
 
+/*
+ * get control page:
+ * atm it is used only by preemption migration overhead code
+ * but it is very general and can be used for different purposes
+ */
+struct control_page* get_ctrl_page(void);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/kernel_iface.c b/src/kernel_iface.c
index dbc4baa..afb6202 100644
--- a/src/kernel_iface.c
+++ b/src/kernel_iface.c
@@ -72,3 +72,16 @@ void exit_np(void)
         }
 }
 
+/* init and return a ptr to the control page for
+ * preemption and migration overhead analysis
+ *
+ * FIXME it may be desirable to have a RO control page here
+ */
+struct control_page* get_ctrl_page(void)
+{
+        if((ctrl_page != NULL) || init_kernel_iface() == 0)
+                return ctrl_page;
+        else
+                return NULL;
+}
+