svn commit: r287846 - stable/10/sys/vm

[Konstantin Belousov]

Author: kib
Date: Wed Sep 16 04:20:39 2015
New Revision: 287846
URL: https://svnweb.freebsd.org/changeset/base/287846

Log:
  MFC r287591:
  There is no reason in the current kernel to disallow write access to
  the COW wired entry if the entry permissions allow it.  Remove the check.

Modified:
  stable/10/sys/vm/vm_map.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/vm/vm_map.c
==============================================================================
--- stable/10/sys/vm/vm_map.c	Wed Sep 16 04:15:46 2015	(r287845)
+++ stable/10/sys/vm/vm_map.c	Wed Sep 16 04:20:39 2015	(r287846)
@@ -3989,12 +3989,10 @@ RetryLookup:;
 		vm_map_unlock_read(map);
 		return (KERN_PROTECTION_FAILURE);
 	}
-	if ((entry->eflags & MAP_ENTRY_USER_WIRED) &&
-	    (entry->eflags & MAP_ENTRY_COW) &&
-	    (fault_type & VM_PROT_WRITE)) {
-		vm_map_unlock_read(map);
-		return (KERN_PROTECTION_FAILURE);
-	}
+	KASSERT((prot & VM_PROT_WRITE) == 0 || (entry->eflags &
+	    (MAP_ENTRY_USER_WIRED | MAP_ENTRY_NEEDS_COPY)) !=
+	    (MAP_ENTRY_USER_WIRED | MAP_ENTRY_NEEDS_COPY),
+	    ("entry %p flags %x", entry, entry->eflags));
 	if ((fault_typea & VM_PROT_COPY) != 0 &&
 	    (entry->max_protection & VM_PROT_WRITE) == 0 &&
 	    (entry->eflags & MAP_ENTRY_COW) == 0) {
@@ -4148,10 +4146,6 @@ vm_map_lookup_locked(vm_map_t *var_map,	
 	fault_type &= VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE;
 	if ((fault_type & prot) != fault_type)
 		return (KERN_PROTECTION_FAILURE);
-	if ((entry->eflags & MAP_ENTRY_USER_WIRED) &&
-	    (entry->eflags & MAP_ENTRY_COW) &&
-	    (fault_type & VM_PROT_WRITE))
-		return (KERN_PROTECTION_FAILURE);
 
 	/*
 	 * If this page is not pageable, we have to get it for all possible