reorder uvm init to avoid use before initialisation.

the particular use before init was in uvm_init step 6, which calls
kmeminit to set up malloc(9), which calls uvm_km_zalloc, which calls
pmap_enter, which calls pool_get, which tries to allocate a page
using km_alloc, which isnt initalised until step 9 in uvm_init.

uvm_km_page_init calls kthread_create though, which uses malloc
internally, so it cant be reordered before malloc init.

to cope with this, uvm_km_page_init is split up. it sets up the
subsystem, and is called before kmeminit. the thread init is moved
to uvm_km_page_lateinit, which is called after kmeminit in uvm_init.

3 files changed, 25 insertions, 9 deletions

diff --git a/sys/uvm/uvm_init.c b/sys/uvm/uvm_init.c
index 9f8300976e0..908031fbdb8 100644
--- a/sys/uvm/uvm_init.c
+++ b/sys/uvm/uvm_init.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_init.c,v 1.39 2015/03/14 03:38:53 jsg Exp $	*/
+/*	$OpenBSD: uvm_init.c,v 1.40 2017/05/11 00:42:05 dlg Exp $	*/
 /*	$NetBSD: uvm_init.c,v 1.14 2000/06/27 17:29:23 mrg Exp $	*/
 
 /*
@@ -114,30 +114,35 @@ uvm_init(void)
 	pmap_init();
 
 	/*
-	 * step 6: init the kernel memory allocator.   after this call the
+	 * step 6: init uvm_km_page allocator memory.
+	 */
+	uvm_km_page_init();
+
+	/*
+	 * step 7: init the kernel memory allocator.   after this call the
 	 * kernel memory allocator (malloc) can be used.
 	 */
 	kmeminit();
 
 	/*
-	 * step 6.5: init the dma allocator, which is backed by pools.
+	 * step 7.5: init the dma allocator, which is backed by pools.
 	 */
 	dma_alloc_init();
 
 	/*
-	 * step 7: init all pagers and the pager_map.
+	 * step 8: init all pagers and the pager_map.
 	 */
 	uvm_pager_init();
 
 	/*
-	 * step 8: init anonymous memory system
+	 * step 9: init anonymous memory system
 	 */
 	amap_init();
 
 	/*
-	 * step 9: init uvm_km_page allocator memory.
+	 * step 10: start uvm_km_page allocator thread.
 	 */
-	uvm_km_page_init();
+	uvm_km_page_lateinit();
 
 	/*
 	 * the VM system is now up!  now that malloc is up we can
diff --git a/sys/uvm/uvm_km.c b/sys/uvm/uvm_km.c
index f76bd87c493..fe733c73353 100644
--- a/sys/uvm/uvm_km.c
+++ b/sys/uvm/uvm_km.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_km.c,v 1.128 2015/09/26 17:55:00 kettenis Exp $	*/
+/*	$OpenBSD: uvm_km.c,v 1.129 2017/05/11 00:42:05 dlg Exp $	*/
 /*	$NetBSD: uvm_km.c,v 1.42 2001/01/14 02:10:01 thorpej Exp $	*/
 
 /* 
@@ -605,6 +605,12 @@ uvm_km_page_init(void)
 	/* nothing */
 }
 
+void
+uvm_km_page_latethread(void)
+{
+	/* nothing */
+}
+
 #else
 /*
  * uvm_km_page allocator, non __HAVE_PMAP_DIRECT archs
@@ -678,7 +684,11 @@ uvm_km_page_init(void)
 	/* tone down if really high */
 	if (uvm_km_pages.lowat > 512)
 		uvm_km_pages.lowat = 512;
+}
 
+void
+uvm_km_page_lateinit(void)
+{
 	kthread_create_deferred(uvm_km_createthread, NULL);
 }
 
diff --git a/sys/uvm/uvm_km.h b/sys/uvm/uvm_km.h
index c851067a0e0..fe7d3951941 100644
--- a/sys/uvm/uvm_km.h
+++ b/sys/uvm/uvm_km.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_km.h,v 1.14 2015/02/07 08:21:24 miod Exp $	*/
+/*	$OpenBSD: uvm_km.h,v 1.15 2017/05/11 00:42:05 dlg Exp $	*/
 /*	$NetBSD: uvm_km.h,v 1.9 1999/06/21 17:25:11 thorpej Exp $	*/
 
 /*
@@ -45,6 +45,7 @@
 
 void uvm_km_init(vaddr_t, vaddr_t, vaddr_t);
 void uvm_km_page_init(void);
+void uvm_km_page_lateinit(void);
 void uvm_km_pgremove(struct uvm_object *, vaddr_t, vaddr_t);
 void uvm_km_pgremove_intrsafe(vaddr_t, vaddr_t);