mcount: Restore/reset rstack only when the return address is hijacked

When specifying estimate_return, the return address is not hijacked.
This patch ensures that mcount_rstack_reset_exception() is not called
in this case, to avoid recording incorrect end times.

Signed-off-by: Yufeng Jin <jinyufeng2000@gmail.com>

libmcount/mcount.c

@@ -1356,7 +1356,7 @@ static int __mcount_entry(unsigned long *parent_loc, unsigned long child, struct
 		return -1;
 	}
 
-	if (unlikely(mtdp->in_exception)) {
+	if (!mcount_estimate_return && unlikely(mtdp->in_exception)) {
 		unsigned long frame_addr;
 
 		/* same as __builtin_frame_addr(2) but avoid warning */
@@ -1493,7 +1493,7 @@ static int __cygprof_entry(unsigned long parent, unsigned long child)
 
 	filtered = mcount_entry_filter_check(mtdp, child, &tr);
 
-	if (unlikely(mtdp->in_exception)) {
+	if (!mcount_estimate_return && unlikely(mtdp->in_exception)) {
 		unsigned long *frame_ptr;
 		unsigned long frame_addr;
 
@@ -1640,7 +1640,7 @@ static void _xray_entry(unsigned long parent, unsigned long child, struct mcount
 
 	filtered = mcount_entry_filter_check(mtdp, child, &tr);
 
-	if (unlikely(mtdp->in_exception)) {
+	if (!mcount_estimate_return && unlikely(mtdp->in_exception)) {
 		unsigned long *frame_ptr;
 		unsigned long frame_addr;