Backout misplaced optimization in vmmap.

(That means the misplaced optimization is back in.)  It broke mips and
possibly other architectures.

1 files changed, 99 insertions, 12 deletions

diff --git a/sys/uvm/uvm_map.c b/sys/uvm/uvm_map.c
index 1081a6dfe0c..6ffe270b394 100644
--- a/sys/uvm/uvm_map.c
+++ b/sys/uvm/uvm_map.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_map.c,v 1.152 2012/04/17 20:22:52 ariane Exp $	*/
+/*	$OpenBSD: uvm_map.c,v 1.153 2012/04/19 12:42:03 ariane Exp $	*/
 /*	$NetBSD: uvm_map.c,v 1.86 2000/11/27 08:40:03 chs Exp $	*/
 
 /*
@@ -3118,21 +3118,108 @@ uvmspace_share(p1, p2)
 void
 uvmspace_exec(struct proc *p, vaddr_t start, vaddr_t end)
 {
-	int pageable = (p->p_vmspace->vm_map.flags & VM_MAP_PAGEABLE);
-	struct vmspace *old, *new;
+	struct vmspace *nvm, *ovm = p->p_vmspace;
+	struct vm_map *map = &ovm->vm_map;
+	struct uvm_map_deadq dead_entries;
 
-	/* Create new vmspace. */
-	new = uvmspace_alloc(start, end, (pageable ? TRUE : FALSE),
-	    TRUE);
-	old = p->p_vmspace;
+	KASSERT((start & (vaddr_t)PAGE_MASK) == 0);
+	KASSERT((end & (vaddr_t)PAGE_MASK) == 0 ||
+	    (end & (vaddr_t)PAGE_MASK) == (vaddr_t)PAGE_MASK);
 
 	pmap_unuse_final(p);   /* before stack addresses go away */
-	pmap_deactivate(p);
-	p->p_vmspace = new;
-	pmap_activate(p);
+	TAILQ_INIT(&dead_entries);
+
+	/*
+	 * see if more than one process is using this vmspace...
+	 */
+
+	if (ovm->vm_refcnt == 1) {
+		/*
+		 * if p is the only process using its vmspace then we can safely
+		 * recycle that vmspace for the program that is being exec'd.
+		 */
+
+#ifdef SYSVSHM
+		/*
+		 * SYSV SHM semantics require us to kill all segments on an exec
+		 */
+		if (ovm->vm_shm)
+			shmexit(ovm);
+#endif
+
+		/*
+		 * POSIX 1003.1b -- "lock future mappings" is revoked
+		 * when a process execs another program image.
+		 */
+		vm_map_lock(map);
+		vm_map_modflags(map, 0, VM_MAP_WIREFUTURE);
+
+		/*
+		 * now unmap the old program
+		 *
+		 * Instead of attempting to keep the map valid, we simply
+		 * nuke all entries and ask uvm_map_setup to reinitialize
+		 * the map to the new boundaries.
+		 *
+		 * uvm_unmap_remove will actually nuke all entries for us
+		 * (as in, not replace them with free-memory entries).
+		 */
+		uvm_unmap_remove(map, map->min_offset, map->max_offset,
+		    &dead_entries, TRUE, FALSE);
+
+		KDASSERT(RB_EMPTY(&map->addr));
+
+		/*
+		 * Nuke statistics and boundaries.
+		 */
+		bzero(&ovm->vm_startcopy,
+		    (caddr_t) (ovm + 1) - (caddr_t) &ovm->vm_startcopy);
 
-	/* Throw away the old vmspace. */
-	uvmspace_free(old);
+
+		if (end & (vaddr_t)PAGE_MASK) {
+			end += 1;
+			if (end == 0) /* overflow */
+				end -= PAGE_SIZE;
+		}
+
+		/*
+		 * Setup new boundaries and populate map with entries.
+		 */
+		map->min_offset = start;
+		map->max_offset = end;
+		uvm_map_setup_entries(map);
+		vm_map_unlock(map);
+
+		/*
+		 * but keep MMU holes unavailable
+		 */
+		pmap_remove_holes(map);
+
+	} else {
+
+		/*
+		 * p's vmspace is being shared, so we can't reuse it for p since
+		 * it is still being used for others.   allocate a new vmspace
+		 * for p
+		 */
+		nvm = uvmspace_alloc(start, end,
+		    (map->flags & VM_MAP_PAGEABLE) ? TRUE : FALSE, TRUE);
+
+		/*
+		 * install new vmspace and drop our ref to the old one.
+		 */
+
+		pmap_deactivate(p);
+		p->p_vmspace = nvm;
+		pmap_activate(p);
+
+		uvmspace_free(ovm);
+	}
+
+	/*
+	 * Release dead entries
+	 */
+	uvm_unmap_detach(&dead_entries, 0);
 }
 
 /*