Module Name: src
Committed By: maxv
Date: Wed Jul 20 13:11:58 UTC 2016
Modified Files:
src/sys/kern: subr_kobj.c
Log Message:
Change the protection of the kernel modules segments once we are done
relocating them. The text is allocated as RWX, and then mprotected to RW.
There is a bug that prevents us from doing RW->RX on amd64 and perhaps
sparc64. On x86, the pmap waits for the page to fault before granting it
the X permission. But in the trap handler, such a page is considered as
belonging to kernel_map, while it actually belongs to module_map. The
kernel then finds out the page is not present in kernel_map, and panics.
In all cases, module_map is non pageable, so even if the trap were handled
properly, it still wouldn't work.
Therefore, there is a small window in which the segment is RWX. But that's
fine enough, for now.
To generate a diff of this commit:
cvs rdiff -u -r1.55 -r1.56 src/sys/kern/subr_kobj.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/subr_kobj.c
diff -u src/sys/kern/subr_kobj.c:1.55 src/sys/kern/subr_kobj.c:1.56
--- src/sys/kern/subr_kobj.c:1.55 Sat Jul 9 07:25:00 2016
+++ src/sys/kern/subr_kobj.c Wed Jul 20 13:11:58 2016
@@ -1,4 +1,4 @@
-/* $NetBSD: subr_kobj.c,v 1.55 2016/07/09 07:25:00 maxv Exp $ */
+/* $NetBSD: subr_kobj.c,v 1.56 2016/07/20 13:11:58 maxv Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -63,7 +63,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_kobj.c,v 1.55 2016/07/09 07:25:00 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_kobj.c,v 1.56 2016/07/20 13:11:58 maxv Exp $");
#ifdef _KERNEL_OPT
#include "opt_modular.h"
@@ -706,6 +706,10 @@ kobj_affix(kobj_t ko, const char *name)
/* Jettison unneeded memory post-link. */
kobj_jettison(ko);
+ /* Change the memory protections, when needed. */
+ uvm_km_protect(module_map, ko->ko_text_address, ko->ko_text_size,
+ VM_PROT_READ|VM_PROT_EXECUTE);
+
/*
* Notify MD code that a module has been loaded.
*
