Introduce a md pmap hook, pmap_remove_holes(), which is supposed to mark

the holes a MMU may have from a given vm_map. This will be automagically
invoked for newly created vmspaces.

On platforms with MMU holes (e.g. sun4, sun4c and vax), this prevents
mmap(2) hints which would end up being in the hole to be accepted as valid,
causing unexpected signals when the process tries to access the hole
(since pmap can not fill the hole anyway).

Unfortunately, the logic mmap() uses to pick a valid address for anonymous
mappings needs work, as it will only try to find an address higher than the
hint, which causes all mmap() with a hint in the hole to fail on vax. This
will be improved later.

2 files changed, 22 insertions, 2 deletions

diff --git a/sys/arch/sparc/include/pmap.h b/sys/arch/sparc/include/pmap.h
index 8e0e2a94973..449c5b6eb6e 100644
--- a/sys/arch/sparc/include/pmap.h
+++ b/sys/arch/sparc/include/pmap.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.h,v 1.41 2007/06/06 17:15:12 deraadt Exp $	*/
+/*	$OpenBSD: pmap.h,v 1.42 2007/09/10 18:49:45 miod Exp $	*/
 /*	$NetBSD: pmap.h,v 1.30 1997/08/04 20:00:47 pk Exp $ */
 
 /*
@@ -283,6 +283,7 @@ vaddr_t		pmap_map(vaddr_t, paddr_t, paddr_t, int);
 void		pmap_reference(pmap_t);
 void		pmap_release(pmap_t);
 void		pmap_remove(pmap_t, vaddr_t, vaddr_t);
+void		pmap_remove_holes(struct vm_map *);
 int		pmap_page_index(paddr_t);
 void		pmap_virtual_space(vaddr_t *, vaddr_t *);
 void		pmap_redzone(void);
diff --git a/sys/arch/sparc/sparc/pmap.c b/sys/arch/sparc/sparc/pmap.c
index 5eceee1cffd..56f03b9ccb6 100644
--- a/sys/arch/sparc/sparc/pmap.c
+++ b/sys/arch/sparc/sparc/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.145 2007/06/06 17:15:12 deraadt Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.146 2007/09/10 18:49:45 miod Exp $	*/
 /*	$NetBSD: pmap.c,v 1.118 1998/05/19 19:00:18 thorpej Exp $ */
 
 /*
@@ -6151,6 +6151,25 @@ pmap_prefer(foff, vap)
 }
 
 void
+pmap_remove_holes(struct vm_map *map)
+{
+#if defined(SUN4) || defined(SUN4C)
+	if (mmu_has_hole) {
+		vaddr_t shole, ehole;
+
+		shole = max(vm_map_min(map), (vaddr_t)MMU_HOLE_START);
+		ehole = min(vm_map_max(map), (vaddr_t)MMU_HOLE_END);
+
+		if (ehole <= shole)
+			return;
+
+		uvm_map_reserve(map, ehole - shole, UVM_UNKNOWN_OFFSET,
+		    0, &shole);
+	}
+#endif
+}
+
+void
 pmap_redzone()
 {
 #if defined(SUN4M)