1 files changed, 102 insertions, 0 deletions

diff --git a/litmus/trace.c b/litmus/trace.c
new file mode 100644
index 000000000000..5735d28f5e30
--- /dev/null
+++ b/litmus/trace.c
@@ -0,0 +1,102 @@
+#include <linux/module.h>
+
+#include <litmus/ftdev.h>
+#include <litmus/litmus.h>
+#include <litmus/trace.h>
+
+/******************************************************************************/
+/*                          Allocation                                        */
+/******************************************************************************/
+
+static struct ftdev overhead_dev;
+
+#define trace_ts_buf overhead_dev.minor[0].buf
+
+static unsigned int ts_seq_no = 0;
+
+static inline void __save_timestamp_cpu(unsigned long event,
+                                        uint8_t type, uint8_t cpu)
+{
+        unsigned int seq_no;
+        struct timestamp *ts;
+        seq_no = fetch_and_inc((int *) &ts_seq_no);
+        if (ft_buffer_start_write(trace_ts_buf, (void**)  &ts)) {
+                ts->event     = event;
+                ts->timestamp = ft_timestamp();
+                ts->seq_no    = seq_no;
+                ts->cpu       = cpu;
+                ts->task_type = type;
+                ft_buffer_finish_write(trace_ts_buf, ts);
+        }
+}
+
+static inline void __save_timestamp(unsigned long event,
+                                   uint8_t type)
+{
+        __save_timestamp_cpu(event, type, raw_smp_processor_id());
+}
+
+feather_callback void save_timestamp(unsigned long event)
+{
+        __save_timestamp(event, TSK_UNKNOWN);
+}
+
+feather_callback void save_timestamp_def(unsigned long event,
+                                         unsigned long type)
+{
+        __save_timestamp(event, (uint8_t) type);
+}
+
+feather_callback void save_timestamp_task(unsigned long event,
+                                          unsigned long t_ptr)
+{
+        int rt = is_realtime((struct task_struct *) t_ptr);
+        __save_timestamp(event, rt ? TSK_RT : TSK_BE);
+}
+
+feather_callback void save_timestamp_cpu(unsigned long event,
+                                         unsigned long cpu)
+{
+        __save_timestamp_cpu(event, TSK_UNKNOWN, cpu);
+}
+
+/******************************************************************************/
+/*                        DEVICE FILE DRIVER                                  */
+/******************************************************************************/
+
+/*
+ * should be 8M; it is the max we can ask to buddy system allocator (MAX_ORDER)
+ * and we might not get as much
+ */
+#define NO_TIMESTAMPS (2 << 11)
+
+#define FT_TRACE_MAJOR  252
+
+static int alloc_timestamp_buffer(struct ftdev* ftdev, unsigned int idx)
+{
+        unsigned int count = NO_TIMESTAMPS;
+        while (count && !trace_ts_buf) {
+                printk("time stamp buffer: trying to allocate %u time stamps.\n", count);
+                ftdev->minor[idx].buf = alloc_ft_buffer(count, sizeof(struct timestamp));
+                count /= 2;
+        }
+        return ftdev->minor[idx].buf ? 0 : -ENOMEM;
+}
+
+static void free_timestamp_buffer(struct ftdev* ftdev, unsigned int idx)
+{
+        free_ft_buffer(ftdev->minor[idx].buf);
+        ftdev->minor[idx].buf = NULL;
+}
+
+static int __init init_ft_overhead_trace(void)
+{
+        printk("Initializing Feather-Trace overhead tracing device.\n");
+        ftdev_init(&overhead_dev, THIS_MODULE);
+        overhead_dev.minor_cnt = 1; /* only one buffer */
+        overhead_dev.alloc = alloc_timestamp_buffer;
+        overhead_dev.free  = free_timestamp_buffer;
+        return register_ftdev(&overhead_dev, "ft_trace", FT_TRACE_MAJOR);
+}
+
+module_init(init_ft_overhead_trace);