[src/trunk]: src/lib/libc/arch/aarch64/sys Update the unwinder comment to bet...

[skrll <skrll%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/39c242e21adc
branches:  trunk
changeset: 1015468:39c242e21adc
user:      skrll <skrll%NetBSD.org@localhost>
date:      Sat Oct 24 07:02:20 2020 +0000

description:
Update the unwinder comment to better reflect ARM64

diffstat:

 lib/libc/arch/aarch64/sys/__sigtramp2.S |  13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)

diffs (28 lines):

diff -r eba1f2c5639f -r 39c242e21adc lib/libc/arch/aarch64/sys/__sigtramp2.S
--- a/lib/libc/arch/aarch64/sys/__sigtramp2.S   Sat Oct 24 07:00:26 2020 +0000
+++ b/lib/libc/arch/aarch64/sys/__sigtramp2.S   Sat Oct 24 07:02:20 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: __sigtramp2.S,v 1.5 2020/10/24 07:00:26 skrll Exp $ */
+/* $NetBSD: __sigtramp2.S,v 1.6 2020/10/24 07:02:20 skrll Exp $ */
 
 /*-
  * Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -41,12 +41,13 @@
  *             ucontext structure
  *     sp->    siginfo structure
  * and x28 points to the ucontext
- *
- * The unwind entry includes the one byte prior to the trampoline
+ */
+
+/*
+ * The unwind entry includes the one instruction prior to the trampoline
  * because the unwinder will look up (return PC - 1) while unwinding.
- * Normally (return PC - 1) computes an address inside the call
- * instruction that created the child frame, but here there is no call
- * instruction so we have to manually add padding.
+ * Normally this would be the jump / branch, but since there isn't one in
+ * this case, we place an explicit nop there instead.
  */
        .cfi_startproc simple
        .cfi_signal_frame