mmiotrace: handle TRACE_PRINT entries

Also make trace_seq_print_cont() non-static, and add a newline if the
seq buffer can't hold all data.
Signed-off-by: Pekka Paalanen <pq@iki.fi>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/trace/trace.c

@@ -199,23 +199,6 @@ unsigned long nsecs_to_usecs(unsigned long nsecs)
 	return nsecs / 1000;
 }
 
-/*
- * trace_flag_type is an enumeration that holds different
- * states when a trace occurs. These are:
- *  IRQS_OFF	- interrupts were disabled
- *  NEED_RESCED - reschedule is requested
- *  HARDIRQ	- inside an interrupt handler
- *  SOFTIRQ	- inside a softirq handler
- *  CONT	- multiple entries hold the trace item
- */
-enum trace_flag_type {
-	TRACE_FLAG_IRQS_OFF		= 0x01,
-	TRACE_FLAG_NEED_RESCHED		= 0x02,
-	TRACE_FLAG_HARDIRQ		= 0x04,
-	TRACE_FLAG_SOFTIRQ		= 0x08,
-	TRACE_FLAG_CONT			= 0x10,
-};
-
 /*
  * TRACE_ITER_SYM_MASK masks the options in trace_flags that
  * control the output of kernel symbols.
@@ -1517,12 +1500,16 @@ lat_print_timestamp(struct trace_seq *s, unsigned long long abs_usecs,
 
 static const char state_to_char[] = TASK_STATE_TO_CHAR_STR;
 
-static void
-trace_seq_print_cont(struct trace_seq *s, struct trace_iterator *iter)
+/*
+ * The message is supposed to contain an ending newline.
+ * If the printing stops prematurely, try to add a newline of our own.
+ */
+void trace_seq_print_cont(struct trace_seq *s, struct trace_iterator *iter)
 {
 	struct trace_array *tr = iter->tr;
 	struct trace_array_cpu *data = tr->data[iter->cpu];
 	struct trace_entry *ent;
+	bool ok = true;
 
 	ent = trace_entry_idx(tr, data, iter, iter->cpu);
 	if (!ent || ent->type != TRACE_CONT) {
@@ -1531,10 +1518,14 @@ trace_seq_print_cont(struct trace_seq *s, struct trace_iterator *iter)
 	}
 
 	do {
-		trace_seq_printf(s, "%s", ent->cont.buf);
+		if (ok)
+			ok = (trace_seq_printf(s, "%s", ent->cont.buf) > 0);
 		__trace_iterator_increment(iter, iter->cpu);
 		ent = trace_entry_idx(tr, data, iter, iter->cpu);
 	} while (ent && ent->type == TRACE_CONT);
+
+	if (!ok)
+		trace_seq_putc(s, '\n');
 }
 
 static int

kernel/trace/trace.h

@@ -71,6 +71,23 @@ struct print_entry {
 	char			buf[];
 };
 
+/*
+ * trace_flag_type is an enumeration that holds different
+ * states when a trace occurs. These are:
+ *  IRQS_OFF	- interrupts were disabled
+ *  NEED_RESCED - reschedule is requested
+ *  HARDIRQ	- inside an interrupt handler
+ *  SOFTIRQ	- inside a softirq handler
+ *  CONT	- multiple entries hold the trace item
+ */
+enum trace_flag_type {
+	TRACE_FLAG_IRQS_OFF		= 0x01,
+	TRACE_FLAG_NEED_RESCHED		= 0x02,
+	TRACE_FLAG_HARDIRQ		= 0x04,
+	TRACE_FLAG_SOFTIRQ		= 0x08,
+	TRACE_FLAG_CONT			= 0x10,
+};
+
 /*
  * The trace field - the most basic unit of tracing. This is what
  * is printed in the end as a single line in the trace output, such as:
@@ -330,6 +347,8 @@ extern int trace_selftest_startup_sysprof(struct tracer *trace,
 
 extern void *head_page(struct trace_array_cpu *data);
 extern int trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
+extern void trace_seq_print_cont(struct trace_seq *s,
+				 struct trace_iterator *iter);
 extern ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
 				 size_t cnt);
 extern long ns2usecs(cycle_t nsec);

kernel/trace/trace_mmiotrace.c

@@ -245,6 +245,27 @@ static int mmio_print_map(struct trace_iterator *iter)
 	return 0;
 }
 
+static int mmio_print_mark(struct trace_iterator *iter)
+{
+	struct trace_entry *entry = iter->ent;
+	const char *msg		= entry->field.print.buf;
+	struct trace_seq *s	= &iter->seq;
+	unsigned long long t	= ns2usecs(entry->field.t);
+	unsigned long usec_rem	= do_div(t, 1000000ULL);
+	unsigned secs		= (unsigned long)t;
+	int ret;
+
+	/* The trailing newline must be in the message. */
+	ret = trace_seq_printf(s, "MARK %lu.%06lu %s", secs, usec_rem, msg);
+	if (!ret)
+		return 0;
+
+	if (entry->field.flags & TRACE_FLAG_CONT)
+		trace_seq_print_cont(s, iter);
+
+	return 1;
+}
+
 /* return 0 to abort printing without consuming current entry in pipe mode */
 static int mmio_print_line(struct trace_iterator *iter)
 {
@@ -253,6 +274,8 @@ static int mmio_print_line(struct trace_iterator *iter)
 		return mmio_print_rw(iter);
 	case TRACE_MMIO_MAP:
 		return mmio_print_map(iter);
+	case TRACE_PRINT:
+		return mmio_print_mark(iter);
 	default:
 		return 1; /* ignore unknown entries */
 	}