[IA64] Add support for enforcing singleshot mmap() semantics at the

privcmd interface.
From: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Keir Fraser <keir@xensource.com>

linux-2.6-xen-sparse/arch/ia64/xen/hypervisor.c

@@ -546,6 +546,7 @@ struct xen_ia64_privcmd_range {
 };
 
 struct xen_ia64_privcmd_vma {
+	int				is_privcmd_mmapped;
 	struct xen_ia64_privcmd_range*	range;
 
 	unsigned long			num_entries;
@@ -684,12 +685,15 @@ __xen_ia64_privcmd_vma_open(struct vm_area_struct* vma,
 static void
 xen_ia64_privcmd_vma_open(struct vm_area_struct* vma)
 {
+	struct xen_ia64_privcmd_vma* old_privcmd_vma = (struct xen_ia64_privcmd_vma*)vma->vm_private_data;
 	struct xen_ia64_privcmd_vma* privcmd_vma = (struct xen_ia64_privcmd_vma*)vma->vm_private_data;
 	struct xen_ia64_privcmd_range* privcmd_range = privcmd_vma->range;
 
 	atomic_inc(&privcmd_range->ref_count);
 	// vm_op->open() can't fail.
 	privcmd_vma = kmalloc(sizeof(*privcmd_vma), GFP_KERNEL | __GFP_NOFAIL);
+	// copy original value if necessary
+	privcmd_vma->is_privcmd_mmapped = old_privcmd_vma->is_privcmd_mmapped;
 
 	__xen_ia64_privcmd_vma_open(vma, privcmd_vma, privcmd_range);
 }
@@ -724,6 +728,14 @@ xen_ia64_privcmd_vma_close(struct vm_area_struct* vma)
 	}
 }
 
+int
+privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma)
+{
+	struct xen_ia64_privcmd_vma* privcmd_vma =
+		(struct xen_ia64_privcmd_vma *)vma->vm_private_data;
+	return (xchg(&privcmd_vma->is_privcmd_mmapped, 1) == 0);
+}
+
 int
 privcmd_mmap(struct file * file, struct vm_area_struct * vma)
 {
@@ -749,6 +761,8 @@ privcmd_mmap(struct file * file, struct vm_area_struct * vma)
 	if (privcmd_vma == NULL) {
 		goto out_enomem1;
 	}
+	privcmd_vma->is_privcmd_mmapped = 0;
+
 	res = kzalloc(sizeof(*res), GFP_KERNEL);
 	if (res == NULL) {
 		goto out_enomem1;

linux-2.6-xen-sparse/drivers/xen/privcmd/privcmd.c

@@ -35,14 +35,9 @@
 static struct proc_dir_entry *privcmd_intf;
 static struct proc_dir_entry *capabilities_intf;
 
-static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma)
-{
 #ifndef HAVE_ARCH_PRIVCMD_MMAP
-	if (xchg(&vma->vm_private_data, (void *)1) != NULL)
-		return 0;
+static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma);
 #endif
-	return 1;
-}
 
 static int privcmd_ioctl(struct inode *inode, struct file *file,
 			 unsigned int cmd, unsigned long data)
@@ -255,6 +250,11 @@ static int privcmd_mmap(struct file * file, struct vm_area_struct * vma)
 
 	return 0;
 }
+
+static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma)
+{
+	return (xchg(&vma->vm_private_data, (void *)1) == NULL);
+}
 #endif
 
 static struct file_operations privcmd_file_ops = {

linux-2.6-xen-sparse/include/asm-ia64/hypervisor.h

@@ -138,6 +138,7 @@ int direct_remap_pfn_range(struct vm_area_struct *vma,
 			   pgprot_t prot,
 			   domid_t  domid);
 struct file;
+int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma);
 int privcmd_mmap(struct file * file, struct vm_area_struct * vma);
 #define HAVE_ARCH_PRIVCMD_MMAP