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, 15 insertions, 5 deletions

diff --git a/sys/vm/device_pager.c b/sys/vm/device_pager.c
index 0d762de..c7f5593 100644
--- a/sys/vm/device_pager.c
+++ b/sys/vm/device_pager.c
@@ -93,6 +93,17 @@ dev_pager_init()
 	    UMA_ZONE_NOFREE|UMA_ZONE_VM); 
 }
 
+static __inline int
+dev_mmap(struct cdevsw *csw, struct cdev *dev, vm_offset_t offset,
+    vm_paddr_t *paddr, int nprot, vm_memattr_t *memattr)
+{
+
+	if (csw->d_flags & D_MMAP2)
+		return (csw->d_mmap2(dev, offset, paddr, nprot, memattr));
+	else
+		return (csw->d_mmap(dev, offset, paddr, nprot));
+}
+
 /*
  * MPSAFE
  */
@@ -106,6 +117,7 @@ dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
 	unsigned int npages;
 	vm_paddr_t paddr;
 	vm_offset_t off;
+	vm_memattr_t dummy;
 	struct cdevsw *csw;
 
 	/*
@@ -133,7 +145,7 @@ dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
 	 */
 	npages = OFF_TO_IDX(size);
 	for (off = foff; npages--; off += PAGE_SIZE)
-		if ((*csw->d_mmap)(dev, off, &paddr, (int)prot) != 0) {
+		if (dev_mmap(csw, dev, off, &paddr, (int)prot, &dummy) != 0) {
 			dev_relthread(dev);
 			return (NULL);
 		}
@@ -214,7 +226,6 @@ dev_pager_getpages(object, m, count, reqpage)
 	vm_memattr_t memattr;
 	struct cdev *dev;
 	int i, ret;
-	int prot;
 	struct cdevsw *csw;
 	struct thread *td;
 	struct file *fpop;
@@ -228,12 +239,11 @@ dev_pager_getpages(object, m, count, reqpage)
 	csw = dev_refthread(dev);
 	if (csw == NULL)
 		panic("dev_pager_getpage: no cdevsw");
-	prot = PROT_READ;	/* XXX should pass in? */
-
 	td = curthread;
 	fpop = td->td_fpop;
 	td->td_fpop = NULL;
-	ret = (*csw->d_mmap)(dev, (vm_offset_t)offset << PAGE_SHIFT, &paddr, prot);
+	ret = dev_mmap(csw, dev, (vm_offset_t)offset << PAGE_SHIFT, &paddr,
+	    PROT_READ, &memattr);
 	KASSERT(ret == 0, ("dev_pager_getpage: map function returns error"));
 	td->td_fpop = fpop;
 	dev_relthread(dev);