Let the VM system know that on certain arch's that VM_PROT_READ

also implies VM_PROT_EXEC.  We support it that way for now,
since the break system call by default gives VM_PROT_ALL.  Now
we have a better chance of coalesing map entries when mixing
mmap/break type operations.  This was contributing to excessive
numbers of map entries on the modula-3 runtime system.  The
problem is still not "solved", but the situation makes more
sense.

Eventually, when we work on architectures where VM_PROT_READ
is orthogonal to VM_PROT_EXEC, we will have to visit this
issue carefully (esp. regarding security issues.)

3 files changed, 19 insertions, 3 deletions

diff --git a/sys/amd64/include/vmparam.h b/sys/amd64/include/vmparam.h
index 48b570d..5c3774e 100644
--- a/sys/amd64/include/vmparam.h
+++ b/sys/amd64/include/vmparam.h
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)vmparam.h	5.9 (Berkeley) 5/12/91
- *	$Id: vmparam.h,v 1.20 1996/04/30 12:02:12 phk Exp $
+ *	$Id: vmparam.h,v 1.21 1996/05/02 14:20:07 phk Exp $
  */
 
 
@@ -47,6 +47,8 @@
  * Machine dependent constants for 386.
  */
 
+#define VM_PROT_READ_IS_EXEC	/* if you can read -- then you can exec */
+
 /*
  * Virtual memory related constants, all in bytes
  */
diff --git a/sys/i386/include/vmparam.h b/sys/i386/include/vmparam.h
index 48b570d..5c3774e 100644
--- a/sys/i386/include/vmparam.h
+++ b/sys/i386/include/vmparam.h
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)vmparam.h	5.9 (Berkeley) 5/12/91
- *	$Id: vmparam.h,v 1.20 1996/04/30 12:02:12 phk Exp $
+ *	$Id: vmparam.h,v 1.21 1996/05/02 14:20:07 phk Exp $
  */
 
 
@@ -47,6 +47,8 @@
  * Machine dependent constants for 386.
  */
 
+#define VM_PROT_READ_IS_EXEC	/* if you can read -- then you can exec */
+
 /*
  * Virtual memory related constants, all in bytes
  */
diff --git a/sys/vm/vm_mmap.c b/sys/vm/vm_mmap.c
index 3d89951..abd6ff6 100644
--- a/sys/vm/vm_mmap.c
+++ b/sys/vm/vm_mmap.c
@@ -38,7 +38,7 @@
  * from: Utah $Hdr: vm_mmap.c 1.6 91/10/21$
  *
  *	@(#)vm_mmap.c	8.4 (Berkeley) 1/12/94
- * $Id: vm_mmap.c,v 1.55 1996/12/22 23:17:09 joerg Exp $
+ * $Id: vm_mmap.c,v 1.56 1996/12/28 22:40:44 dyson Exp $
  */
 
 /*
@@ -475,6 +475,10 @@ mprotect(p, uap, retval)
 	addr = (vm_offset_t) uap->addr;
 	size = uap->len;
 	prot = uap->prot & VM_PROT_ALL;
+#if defined(VM_PROT_READ_IS_EXEC)
+	if (prot & VM_PROT_READ)
+		prot |= VM_PROT_EXECUTE;
+#endif
 
 	pageoff = (addr & PAGE_MASK);
 	addr -= pageoff;
@@ -927,6 +931,14 @@ vm_mmap(map, addr, size, prot, maxprot, flags, handle, foff)
 		docow = MAP_COPY_ON_WRITE | MAP_COPY_NEEDED;
 	}
 
+#if defined(VM_PROT_READ_IS_EXEC)
+	if (prot & VM_PROT_READ)
+		prot |= VM_PROT_EXECUTE;
+
+	if (maxprot & VM_PROT_READ)
+		maxprot |= VM_PROT_EXECUTE;
+#endif
+
 	rv = vm_map_find(map, object, foff, addr, size, fitit,
 			prot, maxprot, docow);