ftrace, orc, x86, tracing: Fix stack traces again

index be86a865087a..bcc295c0a12f 100644
@@ -74,8 +74,50 @@ static struct orc_entry *orc_module_find(unsigned long ip)
 }
 #endif
 
+#ifdef CONFIG_FUNCTION_TRACER
+static struct orc_entry *orc_find(unsigned long ip);
+
+/*
+ * Ftrace dynamic trampolines do not have orc entries of their own.
+ * But they are copies of the ftrace entries that are static and
+ * defined in ftrace_*.S, which do have orc entries.
+ *
+ * If the undwinder comes across a ftrace trampoline, then find the
+ * ftrace function that was used to create it, and use that ftrace
+ * function's orc entrie, as the placement of the return code in
+ * the stack will be identical.
+ */
+static struct orc_entry *orc_ftrace_find(unsigned long ip)
+{
+	struct ftrace_ops *ops;
+	unsigned long caller;
+
+	ops = ftrace_ops_trampoline(ip);
+	if (!ops)
+		return NULL;
+
+	if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
+		caller = (unsigned long)ftrace_regs_call;
+	else
+		caller = (unsigned long)ftrace_call;
+
+	/* Prevent unlikely recursion */
+	if (ip == caller)
+		return NULL;
+
+	return orc_find(caller);
+}
+#else
+static struct orc_entry *orc_ftrace_find(unsigned long ip)
+{
+	return NULL;
+}
+#endif
+
 static struct orc_entry *orc_find(unsigned long ip)
 {
+	static struct orc_entry *orc;
+
 	if (!orc_init)
 		return NULL;
 

@@ -111,7 +153,11 @@ static struct orc_entry *orc_find(unsigned long ip)
 				  __stop_orc_unwind_ip - __start_orc_unwind_ip, ip);
 
 	/* Module lookup: */
-	return orc_module_find(ip);
+	orc = orc_module_find(ip);
+	if (orc)
+		return orc;
+
+	return orc_ftrace_find(ip);
 }
 
 static void orc_sort_swap(void *_a, void *_b, int size)

index 2bab81951ced..3319df9727aa 100644
@@ -332,6 +332,8 @@ extern int ftrace_text_reserved(const void *start, const void *end);
 
 extern int ftrace_nr_registered_ops(void);
 
+struct ftrace_ops *ftrace_ops_trampoline(unsigned long addr);
+
 bool is_ftrace_trampoline(unsigned long addr);
 
 /*

index ccdf3664e4a9..bc1d66fe3728 100644
@@ -1119,15 +1119,11 @@ static struct ftrace_ops global_ops = {
 };
 
 /*
- * This is used by __kernel_text_address() to return true if the
- * address is on a dynamically allocated trampoline that would
- * not return true for either core_kernel_text() or
- * is_module_text_address().
+ * Used by the stack undwinder to know about dynamic ftrace trampolines.
  */
-bool is_ftrace_trampoline(unsigned long addr)
+struct ftrace_ops *ftrace_ops_trampoline(unsigned long addr)
 {
-	struct ftrace_ops *op;
-	bool ret = false;
+	struct ftrace_ops *op = NULL;
 
 	/*
 	 * Some of the ops may be dynamically allocated,

@@ -1143,16 +1139,24 @@ bool is_ftrace_trampoline(unsigned long addr)
 		 */
 		if (op->trampoline && op->trampoline_size)
 			if (addr >= op->trampoline &&
-			    addr < op->trampoline + op->trampoline_size) {
-				ret = true;
+			    addr < op->trampoline + op->trampoline_size)
 				goto out;
-			}
 	} while_for_each_ftrace_op(op);
 
  out:
 	preempt_enable_notrace();
+	return op;
+}
 
-	return ret;
+/*
+ * This is used by __kernel_text_address() to return true if the
+ * address is on a dynamically allocated trampoline that would
+ * not return true for either core_kernel_text() or
+ * is_module_text_address().
+ */
+bool is_ftrace_trampoline(unsigned long addr)
+{
+	return ftrace_ops_trampoline(addr) != NULL;
 }
 
 struct ftrace_page {

index 2a8d8a294345..8e3f20a18a06 100644
@@ -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);
 }

index f2ac9d44f6c4..87411482a46f 100644
@@ -1123,13 +1123,22 @@ static __init int register_trigger_snapshot_cmd(void) { return 0; }
 #endif /* CONFIG_TRACER_SNAPSHOT */
 
 #ifdef CONFIG_STACKTRACE
+#ifdef CONFIG_UNWINDER_ORC
+/* Skip 2:
+ *   event_triggers_post_call()
+ *   trace_event_raw_event_xxx()
+ */
+# define STACK_SKIP 2
+#else
 /*
- * Skip 3:
+ * Skip 4:
  *   stacktrace_trigger()
  *   event_triggers_post_call()
+ *   trace_event_buffer_commit()
  *   trace_event_raw_event_xxx()
  */
-#define STACK_SKIP 3
+#define STACK_SKIP 4
+#endif
 
 static void
 stacktrace_trigger(struct event_trigger_data *data, void *rec)

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