From cac8399523560e52787028fe124bc03aaecc1ef0 Mon Sep 17 00:00:00 2001
From: niklas <niklas@openbsd.org>
Date: Thu, 18 Apr 1996 15:58:33 +0000
Subject: [PATCH] Support mapping of page zero read-only if
 COMPAT_SVR4_MAP_PAGE_ZERO is used.  Dell SVR4 behaved this way, and some
 binaries rely on such icky behaviour.

---
 sys/kern/exec_elf.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/sys/kern/exec_elf.c b/sys/kern/exec_elf.c
index a32eaabe1b5..b07a0ded462 100644
--- a/sys/kern/exec_elf.c
+++ b/sys/kern/exec_elf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: exec_elf.c,v 1.3 1996/03/03 17:19:37 niklas Exp $	*/
+/*	$OpenBSD: exec_elf.c,v 1.4 1996/04/18 15:58:33 niklas Exp $	*/
 /*	$NetBSD: exec_elf.c,v 1.6 1996/02/09 18:59:18 christos Exp $	*/
 
 /*
@@ -531,6 +531,12 @@ exec_elf_makecmds(p, epp)
 	} else
 		epp->ep_entry = eh->e_entry;
 
+#ifdef COMPAT_SVR4_MAP_PAGE_ZERO
+	/* Dell SVR4 maps page zero, yeuch! */
+	NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, NBPG, 0, epp->ep_vp, 0,
+	    VM_PROT_READ);
+#endif
+
 	free((char *) ph, M_TEMP);
 	epp->ep_vp->v_flag |= VTEXT;
 	return exec_aout_setup_stack(p, epp);
-- 
2.20.1