Extend the device pager to support different memory attributes on different

pages in an object.
- Add a new variant of d_mmap() currently called d_mmap2() which accepts
  an additional in/out parameter that is the memory attribute to use for
  the requested page.
- A driver either uses d_mmap() or d_mmap2() for all requests but not both.
  The current implementation uses a flag in the cdevsw (D_MMAP2) to indicate
  that the driver provides a d_mmap2() handler instead of d_mmap().  This
  is done to make the change ABI compatible with existing drivers and
  MFC'able to 7 and 8.

Submitted by:	alc
MFC after:	1 month

1 files changed, 10 insertions, 4 deletions

diff --git a/sys/kern/kern_conf.c b/sys/kern/kern_conf.c
index 8a5577c..8504e48 100644
--- a/sys/kern/kern_conf.c
+++ b/sys/kern/kern_conf.c
@@ -302,7 +302,7 @@ static struct cdevsw dead_cdevsw = {
 #define no_read		(d_read_t *)enodev
 #define no_write	(d_write_t *)enodev
 #define no_ioctl	(d_ioctl_t *)enodev
-#define no_mmap		(d_mmap_t *)enodev
+#define no_mmap		(d_mmap2_t *)enodev
 #define no_kqfilter	(d_kqfilter_t *)enodev
 #define no_mmap_single	(d_mmap_single_t *)enodev
 
@@ -469,7 +469,8 @@ giant_kqfilter(struct cdev *dev, struct knote *kn)
 }
 
 static int
-giant_mmap(struct cdev *dev, vm_offset_t offset, vm_paddr_t *paddr, int nprot)
+giant_mmap(struct cdev *dev, vm_offset_t offset, vm_paddr_t *paddr, int nprot,
+    vm_memattr_t *memattr)
 {
 	struct cdevsw *dsw;
 	int retval;
@@ -478,7 +479,11 @@ giant_mmap(struct cdev *dev, vm_offset_t offset, vm_paddr_t *paddr, int nprot)
 	if (dsw == NULL)
 		return (ENXIO);
 	mtx_lock(&Giant);
-	retval = dsw->d_gianttrick->d_mmap(dev, offset, paddr, nprot);
+	if (dsw->d_gianttrick->d_flags & D_MMAP2)
+		retval = dsw->d_gianttrick->d_mmap2(dev, offset, paddr, nprot,
+		    memattr);
+	else
+		retval = dsw->d_gianttrick->d_mmap(dev, offset, paddr, nprot);
 	mtx_unlock(&Giant);
 	dev_relthread(dev);
 	return (retval);
@@ -614,6 +619,7 @@ prep_cdevsw(struct cdevsw *devsw)
 		if (devsw->d_gianttrick == NULL) {
 			memcpy(dsw2, devsw, sizeof *dsw2);
 			devsw->d_gianttrick = dsw2;
+			devsw->d_flags |= D_MMAP2;
 			dsw2 = NULL;
 		}
 	}
@@ -634,7 +640,7 @@ prep_cdevsw(struct cdevsw *devsw)
 	FIXUP(d_write,		no_write,	giant_write);
 	FIXUP(d_ioctl,		no_ioctl,	giant_ioctl);
 	FIXUP(d_poll,		no_poll,	giant_poll);
-	FIXUP(d_mmap,		no_mmap,	giant_mmap);
+	FIXUP(d_mmap2,		no_mmap,	giant_mmap);
 	FIXUP(d_strategy,	no_strategy,	giant_strategy);
 	FIXUP(d_kqfilter,	no_kqfilter,	giant_kqfilter);
 	FIXUP(d_mmap_single,	no_mmap_single,	giant_mmap_single);