1999-11-18 Roland McGrath <roland@baalperazim.frob.com>

	* wiring.c (wire_all_memory): Touch pages before wiring.

1 files changed, 31 insertions, 8 deletions

diff --git a/serverboot/wiring.c b/serverboot/wiring.c
index ddcbd373..585a3075 100644
--- a/serverboot/wiring.c
+++ b/serverboot/wiring.c
@@ -1,25 +1,25 @@
-/* 
+/*
  * Mach Operating System
  * Copyright (c) 1991 Carnegie Mellon University
  * All Rights Reserved.
- * 
+ *
  * Permission to use, copy, modify and distribute this software and its
  * documentation is hereby granted, provided that both the copyright
  * notice and this permission notice appear in all copies of the
  * software, derivative works or modified versions, and any portions
  * thereof, and that both notices appear in supporting documentation.
- * 
+ *
  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
- * 
+ *
  * Carnegie Mellon requests users of this software to return to
- * 
+ *
  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  *  School of Computer Science
  *  Carnegie Mellon University
  *  Pittsburgh PA 15213-3890
- * 
+ *
  * any improvements or extensions that they make and grant Carnegie Mellon
  * the rights to redistribute these changes.
  */
@@ -107,7 +107,31 @@ wire_all_memory()
 	    if (MACH_PORT_VALID(object))
 		(void) mach_port_deallocate(this_task, object);
 	    if (protection != VM_PROT_NONE)
-	      wire_memory(address, size, protection);
+	      {
+		/* The VM system cannot cope with a COW fault on another
+		   unrelated virtual copy happening later when we have
+		   wired down the original page.  So we must touch all our
+		   pages before wiring to make sure that only we will ever
+		   use them.  */
+		void *page;
+		if (!(protection & VM_PROT_WRITE))
+		  {
+		    kr = vm_protect(this_task, address, size,
+				    0, max_protection);
+		  }
+		for (page = (void *) address;
+		     page < (void *) (address + size);
+		     page += vm_page_size)
+		  *(volatile int *) page = *(int *) page;
+
+		wire_memory(address, size, protection);
+
+		if (!(protection & VM_PROT_WRITE))
+		  {
+		    kr = vm_protect(this_task, address, size,
+				    0, protection);
+		  }
+	      }
 	    address += size;
 	}
 }
@@ -149,4 +173,3 @@ __vm_allocate (task, address, size, anywhere)
 {
   return vm_allocate (task, address, size, anywhere);
 }
-