From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Fri, 23 Sep 2011 19:54:05 +0000 (-0400)
Subject: xen/v86d: Fix /dev/mem to access memory below 1MB
X-Git-Tag: v2.6.39-400.9.0~830^2~2^2~2
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=0cfd8ac8e702db147a9a664212f597f627b3f7e9;p=users%2Fjedix%2Flinux-maple.git

xen/v86d: Fix /dev/mem to access memory below 1MB

We need to provide the VM_IO (and _PAGE_IOMAP) to see the contents
of the memory below 1MB.

Reported-and-Tested-by: Ben Guthro <ben.guthro@virtualcomputer.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 8fc04b4f311f..a1be5259aabb 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -313,9 +313,14 @@ static int mmap_mem(struct file *file, struct vm_area_struct *vma)
 						&vma->vm_page_prot))
 		return -EINVAL;
 
-	vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
-						 size,
-						 vma->vm_page_prot);
+	vma->vm_flags |= VM_RESERVED | VM_IO | VM_PFNMAP | VM_DONTEXPAND;
+	vma->vm_page_prot =  __pgprot(
+			pgprot_val(vm_get_page_prot(vma->vm_flags)) |
+			_PAGE_IOMAP |
+			pgprot_val(phys_mem_access_prot(file,
+				vma->vm_pgoff,
+				size,
+				vma->vm_page_prot)));
 
 	vma->vm_ops = &mmap_mem_ops;