Export IRQ count to control page

Also add some compile-time checks to detect unexpected offsets.

2 files changed, 18 insertions, 16 deletions

diff --git a/include/litmus/rt_param.h b/include/litmus/rt_param.h
index 6456ed04fddb..8d9aa07cf324 100644
--- a/include/litmus/rt_param.h
+++ b/include/litmus/rt_param.h
@@ -65,12 +65,12 @@ struct rt_task {
 };
 
 union np_flag {
-        uint32_t raw;
+        uint64_t raw;
         struct {
                 /* Is the task currently in a non-preemptive section? */
-                uint32_t flag:31;
+                uint64_t flag:31;
                 /* Should the task call into the scheduler? */
-                uint32_t preempt:1;
+                uint64_t preempt:1;
         } np;
 };
 
@@ -93,13 +93,25 @@ struct control_page {
          * sections. */
         volatile union np_flag sched;
 
+        volatile uint64_t irq_count; /* Incremented by the kernel each time an IRQ is
+                                      * handled. */
+
         /* Locking overhead tracing: userspace records here the time stamp
-         * prior to starting the system call. */
-        uint64_t ts_syscall_start; /* Feather-Trace cycles */
+         * and IRQ counter prior to starting the system call. */
+        uint64_t ts_syscall_start;  /* Feather-Trace cycles */
+        uint64_t irq_syscall_start; /* Snapshot of irq_count when the syscall
+                                     * started. */
 
         /* to be extended */
 };
 
+/* Expected offsets within the control page. */
+
+#define LITMUS_CP_OFFSET_SCHED          0
+#define LITMUS_CP_OFFSET_IRQ_COUNT      8
+#define LITMUS_CP_OFFSET_TS_SC_START    16
+#define LITMUS_CP_OFFSET_IRQ_SC_START   24
+
 /* don't export internal data structures to user space (liblitmus) */
 #ifdef __KERNEL__
 
diff --git a/include/litmus/trace_irq.h b/include/litmus/trace_irq.h
index 01e4b98fc3e0..0d0c042ba9c3 100644
--- a/include/litmus/trace_irq.h
+++ b/include/litmus/trace_irq.h
@@ -3,17 +3,7 @@
 
 #ifdef CONFIG_SCHED_OVERHEAD_TRACE
 
-#include <asm/atomic.h>
-#include <linux/percpu.h>
-
-extern DEFINE_PER_CPU(atomic_t, irq_fired_count);
-
-static inline void ft_irq_fired(void)
-{
-        /* Only called with preemptions disabled.  */
-        atomic_inc(&__get_cpu_var(irq_fired_count));
-}
-
+void ft_irq_fired(void);
 
 #else