[src/trunk]: src/sys/dev Zero clear sh_offset to indicate a section is unused.

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

details:   https://anonhg.NetBSD.org/src/rev/b17bbbb1a229
branches:  trunk
changeset: 989081:b17bbbb1a229
user:      rin <rin%NetBSD.org@localhost>
date:      Mon Oct 11 14:14:40 2021 +0000

description:
Zero clear sh_offset to indicate a section is unused.

Avoid kernel text being doubly allocated due to non-zero sh_offset for
unused sections.

None of MD codes and kern_ksyms.c use sh_type == SHT_NULL (yet?) to
determine whether a section is unused.

diffstat:

 sys/dev/kloader.c |  8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diffs (31 lines):

diff -r 547393ca712e -r b17bbbb1a229 sys/dev/kloader.c
--- a/sys/dev/kloader.c Mon Oct 11 13:42:33 2021 +0000
+++ b/sys/dev/kloader.c Mon Oct 11 14:14:40 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kloader.c,v 1.29 2021/06/29 22:40:53 dholland Exp $    */
+/*     $NetBSD: kloader.c,v 1.30 2021/10/11 14:14:40 rin Exp $ */
 
 /*-
  * Copyright (c) 2001, 2002, 2004 The NetBSD Foundation, Inc.
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kloader.c,v 1.29 2021/06/29 22:40:53 dholland Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kloader.c,v 1.30 2021/10/11 14:14:40 rin Exp $");
 
 #include "debug_kloader.h"
 
@@ -263,9 +263,11 @@
                        symndx = i;
                else if (strcmp(shstrtab + sh[i].sh_name, ".strtab") == 0)
                        strndx = i;
-               else if (i != eh.e_shstrndx)
+               else if (i != eh.e_shstrndx) {
                        /* while here, mark all other sections as unused */
                        sh[i].sh_type = SHT_NULL;
+                       sh[i].sh_offset = 0;
+               }
        }
 
        if (symndx < 0 || strndx < 0) {