Feather-Trace: add platform independent implementation

This patch adds the simple fallback implementation and creates dummy
hooks in the x86 and ARM Kconfig files.

1 files changed, 69 insertions, 0 deletions

diff --git a/include/litmus/feather_trace.h b/include/litmus/feather_trace.h
new file mode 100644
index 000000000000..dbeca46c01f5
--- /dev/null
+++ b/include/litmus/feather_trace.h
@@ -0,0 +1,69 @@
+#ifndef _FEATHER_TRACE_H_
+#define _FEATHER_TRACE_H_
+
+#include <asm/atomic.h>
+
+int ft_enable_event(unsigned long id);
+int ft_disable_event(unsigned long id);
+int ft_is_event_enabled(unsigned long id);
+int ft_disable_all_events(void);
+
+/* atomic_* funcitons are inline anyway */
+static inline int fetch_and_inc(int *val)
+{
+        return atomic_add_return(1, (atomic_t*) val) - 1;
+}
+
+static inline int fetch_and_dec(int *val)
+{
+        return atomic_sub_return(1, (atomic_t*) val) + 1;
+}
+
+static inline void ft_atomic_dec(int *val)
+{
+        atomic_sub(1, (atomic_t*) val);
+}
+
+/* Don't use rewriting implementation if kernel text pages are read-only.
+ * Ftrace gets around this by using the identity mapping, but that's more
+ * effort that is warrented right now for Feather-Trace.
+ * Eventually, it may make sense to replace Feather-Trace with ftrace.
+ */
+#if defined(CONFIG_ARCH_HAS_FEATHER_TRACE) && !defined(CONFIG_DEBUG_RODATA)
+
+#include <asm/feather_trace.h>
+
+#else /* !__ARCH_HAS_FEATHER_TRACE */
+
+/* provide default implementation */
+#include <linux/timex.h> /* for get_cycles() */
+
+static inline unsigned long long ft_timestamp(void)
+{
+        return get_cycles();
+}
+
+#define feather_callback
+
+#define MAX_EVENTS 1024
+
+extern int ft_events[MAX_EVENTS];
+
+#define ft_event(id, callback) \
+        if (ft_events[id]) callback();
+
+#define ft_event0(id, callback) \
+        if (ft_events[id]) callback(id);
+
+#define ft_event1(id, callback, param) \
+        if (ft_events[id]) callback(id, param);
+
+#define ft_event2(id, callback, param, param2) \
+        if (ft_events[id]) callback(id, param, param2);
+
+#define ft_event3(id, callback, p, p2, p3) \
+        if (ft_events[id]) callback(id, p, p2, p3);
+
+#endif /* __ARCH_HAS_FEATHER_TRACE */
+
+#endif