[src/trunk]: src/sys/rump/librump/rumpkern On amd64, allocate module_map memo...

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

details:   https://anonhg.NetBSD.org/src/rev/a67fd09d9a42
branches:  trunk
changeset: 755555:a67fd09d9a42
user:      pooka <pooka%NetBSD.org@localhost>
date:      Wed Jun 09 12:02:37 2010 +0000

description:
On amd64, allocate module_map memory from the lowest 2GB.

diffstat:

 sys/rump/librump/rumpkern/vm.c |  32 ++++++++++++++++++++++++++++----
 1 files changed, 28 insertions(+), 4 deletions(-)

diffs (60 lines):

diff -r 9909636e91d6 -r a67fd09d9a42 sys/rump/librump/rumpkern/vm.c
--- a/sys/rump/librump/rumpkern/vm.c    Wed Jun 09 11:35:36 2010 +0000
+++ b/sys/rump/librump/rumpkern/vm.c    Wed Jun 09 12:02:37 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vm.c,v 1.81 2010/06/09 11:35:36 pooka Exp $    */
+/*     $NetBSD: vm.c,v 1.82 2010/06/09 12:02:37 pooka Exp $    */
 
 /*
  * Copyright (c) 2007-2010 Antti Kantee.  All Rights Reserved.
@@ -43,7 +43,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vm.c,v 1.81 2010/06/09 11:35:36 pooka Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vm.c,v 1.82 2010/06/09 12:02:37 pooka Exp $");
 
 #include <sys/param.h>
 #include <sys/atomic.h>
@@ -528,15 +528,39 @@
 vaddr_t
 uvm_km_alloc(struct vm_map *map, vsize_t size, vsize_t align, uvm_flag_t flags)
 {
-       void *rv;
+       void *rv, *desired = NULL;
        int alignbit, error;
 
+#ifdef __x86_64__
+       /*
+        * On amd64, allocate all module memory from the lowest 2GB.
+        * This is because NetBSD kernel modules are compiled
+        * with -mcmodel=kernel and reserve only 4 bytes for
+        * offsets.  If we load code compiled with -mcmodel=kernel
+        * anywhere except the lowest or highest 2GB, it will not
+        * work.  Since userspace does not have access to the highest
+        * 2GB, use the lowest 2GB.
+        * 
+        * Note: this assumes the rump kernel resides in
+        * the lowest 2GB as well.
+        *
+        * Note2: yes, it's a quick hack, but since this the only
+        * place where we care about the map we're allocating from,
+        * just use a simple "if" instead of coming up with a fancy
+        * generic solution.
+        */
+       extern struct vm_map *module_map;
+       if (map == module_map) {
+               desired = (void *)(0x80000000 - size);
+       }
+#endif
+
        alignbit = 0;
        if (align) {
                alignbit = ffs(align)-1;
        }
 
-       rv = rumpuser_anonmmap(NULL, size, alignbit, flags & UVM_KMF_EXEC,
+       rv = rumpuser_anonmmap(desired, size, alignbit, flags & UVM_KMF_EXEC,
            &error);
        if (rv == NULL) {
                if (flags & (UVM_KMF_CANFAIL | UVM_KMF_NOWAIT))