tracing: Update stack trace skipping for ORC unwinder

With the addition of ORC unwinder and FRAME POINTER unwinder, the stack
trace skipping requirements have changed.

I went through the tracing stack trace dumps with ORC and with frame
pointers and recalculated the proper values.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 20 insertions, 14 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2a8d8a294345..8e3f20a18a06 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2374,6 +2374,15 @@ void trace_event_buffer_commit(struct trace_event_buffer *fbuffer)
 }
 EXPORT_SYMBOL_GPL(trace_event_buffer_commit);
 
+/*
+ * Skip 3:
+ *
+ *   trace_buffer_unlock_commit_regs()
+ *   trace_event_buffer_commit()
+ *   trace_event_raw_event_xxx()
+*/
+# define STACK_SKIP 3
+
 void trace_buffer_unlock_commit_regs(struct trace_array *tr,
 				     struct ring_buffer *buffer,
 				     struct ring_buffer_event *event,
@@ -2383,16 +2392,12 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr,
 	__buffer_unlock_commit(buffer, event);
 
 	/*
-	 * If regs is not set, then skip the following callers:
-	 *   trace_buffer_unlock_commit_regs
-	 *   event_trigger_unlock_commit
-	 *   trace_event_buffer_commit
-	 *   trace_event_raw_event_sched_switch
+	 * If regs is not set, then skip the necessary functions.
 	 * Note, we can still get here via blktrace, wakeup tracer
 	 * and mmiotrace, but that's ok if they lose a function or
-	 * two. They are that meaningful.
+	 * two. They are not that meaningful.
 	 */
-	ftrace_trace_stack(tr, buffer, flags, regs ? 0 : 4, pc, regs);
+	ftrace_trace_stack(tr, buffer, flags, regs ? 0 : STACK_SKIP, pc, regs);
 	ftrace_trace_userstack(buffer, flags, pc);
 }
 
@@ -2579,11 +2584,13 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
 	trace.skip		= skip;
 
 	/*
-	 * Add two, for this function and the call to save_stack_trace()
+	 * Add one, for this function and the call to save_stack_trace()
 	 * If regs is set, then these functions will not be in the way.
 	 */
+#ifndef CONFIG_UNWINDER_ORC
 	if (!regs)
-		trace.skip += 2;
+		trace.skip++;
+#endif
 
 	/*
 	 * Since events can happen in NMIs there's no safe way to
@@ -2711,11 +2718,10 @@ void trace_dump_stack(int skip)
 
 	local_save_flags(flags);
 
-	/*
-	 * Skip 3 more, seems to get us at the caller of
-	 * this function.
-	 */
-	skip += 3;
+#ifndef CONFIG_UNWINDER_ORC
+	/* Skip 1 to skip this function. */
+	skip++;
+#endif
 	__ftrace_trace_stack(global_trace.trace_buffer.buffer,
 			     flags, skip, preempt_count(), NULL);
 }