ftrace: add trace_special()

for ad-hoc tracing.

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

kernel/trace/trace.c

@@ -137,6 +137,7 @@ enum trace_type {
 
 	TRACE_FN,
 	TRACE_CTX,
+	TRACE_SPECIAL,
 
 	__TRACE_LAST_TYPE
 };
@@ -700,6 +701,22 @@ ftrace(struct trace_array *tr, struct trace_array_cpu *data,
 	spin_unlock(&data->lock);
 }
 
+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,
@@ -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;
 }

kernel/trace/trace.h

@@ -25,6 +25,15 @@ struct ctx_switch_entry {
 	unsigned char		next_prio;
 };
 
+/*
+ * 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);