[src/trunk]: src/sys/dev/hpc Restore wscons keymaps feature on hpcarm

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

details:   https://anonhg.NetBSD.org/src/rev/74365d7b857c
branches:  trunk
changeset: 824635:74365d7b857c
user:      manu <manu%NetBSD.org@localhost>
date:      Mon Jun 12 09:23:39 2017 +0000

description:
Restore wscons keymaps feature on hpcarm

hpc ports need to alter keydesc data at runtime in order to load
alternate keymaps. But since keydesc is const initialized data, it
is mapped read only and the operation should fail.

It seems older compiler failed to enforce the read-only mapping and
this is why it used to work, but on recent NetBSD releases, the
feature is broken.

We fix it by duplicating the keydesc data once into a malloc'ed area
that can be modified.

diffstat:

 sys/dev/hpc/hpckbd.c |  35 ++++++++++++++++++++++-------------
 1 files changed, 22 insertions(+), 13 deletions(-)

diffs (65 lines):

diff -r 2872ad205ed7 -r 74365d7b857c sys/dev/hpc/hpckbd.c
--- a/sys/dev/hpc/hpckbd.c      Mon Jun 12 08:19:22 2017 +0000
+++ b/sys/dev/hpc/hpckbd.c      Mon Jun 12 09:23:39 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: hpckbd.c,v 1.30 2012/10/27 17:18:17 chs Exp $ */
+/*     $NetBSD: hpckbd.c,v 1.31 2017/06/12 09:23:39 manu Exp $ */
 
 /*-
  * Copyright (c) 1999-2001 The NetBSD Foundation, Inc.
@@ -30,11 +30,12 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: hpckbd.c,v 1.30 2012/10/27 17:18:17 chs Exp $");
+__KERNEL_RCSID(0, "$NetBSD: hpckbd.c,v 1.31 2017/06/12 09:23:39 manu Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/device.h>
+#include <sys/malloc.h>
 
 #include <sys/tty.h>
 
@@ -264,22 +265,30 @@
                    const keysym_t *map, int mapsize)
 {
        int i;
-       struct wscons_keydesc *desc;
+       const struct wscons_keydesc *desc;
+       static struct wscons_keydesc *ndesc = NULL;
 
-       /* fix keydesc table */
        /* 
-        * XXX The way this is done is really wrong.  The __UNCONST()
-        * is a hint as to what is wrong.  This actually ends up modifying
-        * initialized data which is marked "const".
-        * The reason we get away with it here is apparently that text
-        * and read-only data gets mapped read/write on the platforms
-        * using this code.
+        * fix keydesc table. Since it is const data, we must 
+        * copy it once before changingg it.
         */
-       desc = (struct wscons_keydesc *)__UNCONST(hpckbd_keymapdata.keydesc);
+
+       if (ndesc == NULL) {
+               size_t sz;
+
+               for (sz = 0; hpckbd_keymapdata.keydesc[sz].name != 0; sz++);
+
+               ndesc = malloc(sz * sizeof(*ndesc), M_DEVBUF, M_WAITOK);
+               memcpy(ndesc, hpckbd_keymapdata.keydesc, sz * sizeof(*ndesc));
+
+               hpckbd_keymapdata.keydesc = ndesc;
+       }
+
+       desc = hpckbd_keymapdata.keydesc;
        for (i = 0; desc[i].name != 0; i++) {
                if ((desc[i].name & KB_MACHDEP) && desc[i].map == NULL) {
-                       desc[i].map = map;
-                       desc[i].map_size = mapsize;
+                       ndesc[i].map = map;
+                       ndesc[i].map_size = mapsize;
                }
        }