lguest: assume Switcher text is a single page.

ie. SHARED_SWITCHER_PAGES == 1.  It is well under a page, and it's a
minor simplification: it's nice to have *one* simplification in a
patch series!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index 211d8267992b..4209065b9b1e 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -52,6 +52,13 @@ static __init int map_switcher(void)
          * easy.
          */
 
+        /* We assume Switcher text fits into a single page. */
+        if (end_switcher_text - start_switcher_text > PAGE_SIZE) {
+                printk(KERN_ERR "lguest: switcher text too large (%zu)\n",
+                       end_switcher_text - start_switcher_text);
+                return -EINVAL;
+        }
+
         /*
          * We allocate an array of struct page pointers.  map_vm_area() wants
          * this, rather than just an array of pages.
@@ -326,7 +333,7 @@ static int __init init(void)
                 goto out;
 
         /* Now we set up the pagetable implementation for the Guests. */
-        err = init_pagetables(switcher_pages, SHARED_SWITCHER_PAGES);
+        err = init_pagetables(switcher_pages);
         if (err)
                 goto unmap;