From 47c22847e26564228c8e5ae7701e7f665e652cca Mon Sep 17 00:00:00 2001
From: ariff <ariff@FreeBSD.org>
Date: Sun, 8 Jul 2007 14:01:11 +0000
Subject: [PATCH] MFC:

New sysctl: "hw.snd.compat_linux_mmap" to allow PROT_EXEC page
mapping, due to recent changes in linux compatibility layer which
require it. All linux applications that using sound + mmap() (mostly games)
require this to be enabled. Disabled by default.
---
 sys/dev/sound/pcm/dsp.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/sys/dev/sound/pcm/dsp.c b/sys/dev/sound/pcm/dsp.c
index 48153350864b..be0140d24997 100644
--- a/sys/dev/sound/pcm/dsp.c
+++ b/sys/dev/sound/pcm/dsp.c
@@ -31,6 +31,10 @@
 
 SND_DECLARE_FILE("$FreeBSD$");
 
+static int dsp_mmap_allow_prot_exec = 0;
+SYSCTL_INT(_hw_snd, OID_AUTO, compat_linux_mmap, CTLFLAG_RW,
+    &dsp_mmap_allow_prot_exec, 0, "linux mmap compatibility");
+
 #define OLDPCM_IOCTL
 
 static d_open_t dsp_open;
@@ -1080,7 +1084,15 @@ dsp_mmap(struct cdev *i_dev, vm_offset_t offset, vm_paddr_t *paddr, int nprot)
 {
 	struct pcm_channel *wrch = NULL, *rdch = NULL, *c;
 
-	if (nprot & PROT_EXEC)
+	/*
+	 * Reject PROT_EXEC by default. It just doesn't makes sense.
+	 * Unfortunately, we have to give up this one due to linux_mmap
+	 * changes.
+	 *
+	 * http://lists.freebsd.org/pipermail/freebsd-emulation/2007-June/003698.html
+	 *
+	 */
+	if ((nprot & PROT_EXEC) && dsp_mmap_allow_prot_exec == 0)
 		return -1;
 
 	getchns(i_dev, &rdch, &wrch, SD_F_PRIO_RD | SD_F_PRIO_WR);