ftrace: add trace_special()

for ad-hoc tracing.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 59 insertions, 0 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d78cbc4fc519..fa13059eb462 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -137,6 +137,7 @@ enum trace_type {
 
         TRACE_FN,
         TRACE_CTX,
+        TRACE_SPECIAL,
 
         __TRACE_LAST_TYPE
 };
@@ -701,6 +702,22 @@ ftrace(struct trace_array *tr, struct trace_array_cpu *data,
 }
 
 notrace void
+trace_special(struct trace_array *tr, struct trace_array_cpu *data,
+              unsigned long arg1, unsigned long arg2, unsigned long arg3)
+{
+        struct trace_entry *entry;
+
+        spin_lock(&data->lock);
+        entry                   = tracing_get_trace_entry(tr, data);
+        tracing_generic_entry_update(entry, 0);
+        entry->type             = TRACE_SPECIAL;
+        entry->special.arg1     = arg1;
+        entry->special.arg2     = arg2;
+        entry->special.arg3     = arg3;
+        spin_unlock(&data->lock);
+}
+
+notrace void
 tracing_sched_switch_trace(struct trace_array *tr,
                            struct trace_array_cpu *data,
                            struct task_struct *prev, struct task_struct *next,
@@ -1167,6 +1184,12 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
                                  entry->ctx.next_prio,
                                  comm);
                 break;
+        case TRACE_SPECIAL:
+                trace_seq_printf(s, " %lx %lx %lx\n",
+                                 entry->special.arg1,
+                                 entry->special.arg2,
+                                 entry->special.arg3);
+                break;
         default:
                 trace_seq_printf(s, "Unknown type %d\n", entry->type);
         }
@@ -1234,6 +1257,14 @@ static notrace int print_trace_fmt(struct trace_iterator *iter)
                 if (!ret)
                         return 0;
                 break;
+        case TRACE_SPECIAL:
+                ret = trace_seq_printf(s, " %lx %lx %lx\n",
+                                 entry->special.arg1,
+                                 entry->special.arg2,
+                                 entry->special.arg3);
+                if (!ret)
+                        return 0;
+                break;
         }
         return 1;
 }
@@ -1271,6 +1302,14 @@ static notrace int print_raw_fmt(struct trace_iterator *iter)
                 if (!ret)
                         return 0;
                 break;
+        case TRACE_SPECIAL:
+                ret = trace_seq_printf(s, " %lx %lx %lx\n",
+                                 entry->special.arg1,
+                                 entry->special.arg2,
+                                 entry->special.arg3);
+                if (!ret)
+                        return 0;
+                break;
         }
         return 1;
 }
@@ -1304,6 +1343,11 @@ static notrace int print_bin_fmt(struct trace_iterator *iter)
                 SEQ_PUT_FIELD_RET(s, entry->ctx.next_pid);
                 SEQ_PUT_FIELD_RET(s, entry->ctx.next_prio);
                 break;
+        case TRACE_SPECIAL:
+                SEQ_PUT_FIELD_RET(s, entry->special.arg1);
+                SEQ_PUT_FIELD_RET(s, entry->special.arg2);
+                SEQ_PUT_FIELD_RET(s, entry->special.arg3);
+                break;
         }
         return 1;
 }
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 27fa2d06f499..7bdfef35c05a 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -26,6 +26,15 @@ struct ctx_switch_entry {
 };
 
 /*
+ * Special (free-form) trace entry:
+ */
+struct special_entry {
+        unsigned long           arg1;
+        unsigned long           arg2;
+        unsigned long           arg3;
+};
+
+/*
  * The trace entry - the most basic unit of tracing. This is what
  * is printed in the end as a single line in the trace output, such as:
  *
@@ -41,6 +50,7 @@ struct trace_entry {
         union {
                 struct ftrace_entry             fn;
                 struct ctx_switch_entry         ctx;
+                struct special_entry            special;
         };
 };
 
@@ -154,6 +164,11 @@ void tracing_sched_switch_trace(struct trace_array *tr,
                                 struct task_struct *next,
                                 unsigned long flags);
 void tracing_record_cmdline(struct task_struct *tsk);
+void trace_special(struct trace_array *tr,
+                   struct trace_array_cpu *data,
+                   unsigned long arg1,
+                   unsigned long arg2,
+                   unsigned long arg3);
 
 void tracing_start_function_trace(void);
 void tracing_stop_function_trace(void);