Simplify vmspace initialization. The bcopy() of fields from the old

vmspace to the new vmspace in vmspace_exec() is mostly wasted effort.  With
one exception, vm_swrss, the copied fields are immediately overwritten.
Instead, initialize these fields to zero in vmspace_alloc(), eliminating a
bcopy() from vmspace_exec() and a bzero() from vmspace_fork().

2 files changed, 8 insertions, 14 deletions

diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
index f6ce86c..3d17f97 100644
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -244,7 +244,6 @@ vm_map_zdtor(void *mem, int size, void *arg)
 /*
  * Allocate a vmspace structure, including a vm_map and pmap,
  * and initialize those structures.  The refcnt is set to 1.
- * The remaining fields must be initialized by the caller.
  */
 struct vmspace *
 vmspace_alloc(min, max)
@@ -258,6 +257,13 @@ vmspace_alloc(min, max)
 	vm->vm_map.pmap = vmspace_pmap(vm);		/* XXX */
 	vm->vm_refcnt = 1;
 	vm->vm_shm = NULL;
+	vm->vm_swrss = 0;
+	vm->vm_tsize = 0;
+	vm->vm_dsize = 0;
+	vm->vm_ssize = 0;
+	vm->vm_taddr = 0;
+	vm->vm_daddr = 0;
+	vm->vm_maxsaddr = 0;
 	vm->vm_exitingcnt = 0;
 	return (vm);
 }
@@ -2391,13 +2397,6 @@ vmspace_fork(struct vmspace *vm1)
 	old_map->infork = 1;
 
 	vm2 = vmspace_alloc(old_map->min_offset, old_map->max_offset);
-	/*
-	 * Using vm_{start,end}copy is invalid for more fields than
-	 * it is valid here.  For the most part, initialize size
-	 * fields to zero and update them as map entries are copied
-	 */
-	bzero(&vm2->vm_startcopy,
-	    (caddr_t)&vm2->vm_endcopy - (caddr_t)&vm2->vm_startcopy);
 	vm2->vm_taddr = vm1->vm_taddr;
 	vm2->vm_daddr = vm1->vm_daddr;
 	vm2->vm_maxsaddr = vm1->vm_maxsaddr;
@@ -2829,9 +2828,7 @@ vmspace_exec(struct proc *p, vm_offset_t minuser, vm_offset_t maxuser)
 
 	GIANT_REQUIRED;
 	newvmspace = vmspace_alloc(minuser, maxuser);
-	bcopy(&oldvmspace->vm_startcopy, &newvmspace->vm_startcopy,
-	    (caddr_t) &newvmspace->vm_endcopy -
-	    (caddr_t) &newvmspace->vm_startcopy);
+	newvmspace->vm_swrss = oldvmspace->vm_swrss;
 	/*
 	 * This code is written like this for prototype purposes.  The
 	 * goal is to avoid running down the vmspace here, but let the
diff --git a/sys/vm/vm_map.h b/sys/vm/vm_map.h
index c8cb74f..abd809f 100644
--- a/sys/vm/vm_map.h
+++ b/sys/vm/vm_map.h
@@ -221,8 +221,6 @@ struct vmspace {
 	struct vm_map vm_map;	/* VM address map */
 	struct pmap vm_pmap;	/* private physical map */
 	struct shmmap_state *vm_shm;	/* SYS5 shared memory private data XXX */
-/* we copy between vm_startcopy and vm_endcopy on fork */
-#define vm_startcopy vm_swrss
 	segsz_t vm_swrss;	/* resident set size before last swap */
 	segsz_t vm_tsize;	/* text size (pages) XXX */
 	segsz_t vm_dsize;	/* data size (pages) XXX */
@@ -230,7 +228,6 @@ struct vmspace {
 	caddr_t vm_taddr;	/* (c) user virtual address of text */
 	caddr_t vm_daddr;	/* (c) user virtual address of data */
 	caddr_t vm_maxsaddr;	/* user VA at max stack growth */
-#define	vm_endcopy vm_exitingcnt
 	int	vm_exitingcnt;	/* several processes zombied in exit1  */
 	int	vm_refcnt;	/* number of references */
 };