This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / drivers / xen / util.c

diff --git a/drivers/xen/util.c b/drivers/xen/util.c
new file mode 100644 (file)
index 0000000..7fd108b
--- /dev/null
+++ b/drivers/xen/util.c
@@ -0,0 +1,70 @@
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <asm/uaccess.h>
+#include <xen/driver_util.h>
+
+static int f(pte_t *pte, struct page *pmd_page, unsigned long addr, void *data)
+{
+       /* apply_to_page_range() does all the hard work. */
+       return 0;
+}
+
+struct vm_struct *alloc_vm_area(unsigned long size)
+{
+       struct vm_struct *area;
+
+       area = get_vm_area(size, VM_IOREMAP);
+       if (area == NULL)
+               return NULL;
+
+       /*
+        * This ensures that page tables are constructed for this region
+        * of kernel virtual address space and mapped into init_mm.
+        */
+       if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
+                               area->size, f, NULL)) {
+               free_vm_area(area);
+               return NULL;
+       }
+
+       return area;
+}
+EXPORT_SYMBOL_GPL(alloc_vm_area);
+
+void free_vm_area(struct vm_struct *area)
+{
+       struct vm_struct *ret;
+       ret = remove_vm_area(area->addr);
+       BUG_ON(ret != area);
+       kfree(area);
+}
+EXPORT_SYMBOL_GPL(free_vm_area);
+
+void lock_vm_area(struct vm_struct *area)
+{
+       unsigned long i;
+       char c;
+
+       /*
+        * Prevent context switch to a lazy mm that doesn't have this area
+        * mapped into its page tables.
+        */
+       preempt_disable();
+
+       /*
+        * Ensure that the page tables are mapped into the current mm. The
+        * page-fault path will copy the page directory pointers from init_mm.
+        */
+       for (i = 0; i < area->size; i += PAGE_SIZE)
+               (void)__get_user(c, (char __user *)area->addr + i);
+}
+EXPORT_SYMBOL_GPL(lock_vm_area);
+
+void unlock_vm_area(struct vm_struct *area)
+{
+       preempt_enable();
+}
+EXPORT_SYMBOL_GPL(unlock_vm_area);