vdso: Defer handling untill all zones are restored

In worst case we might be tryin to proxify vdso zone
when vvar only is remmaped but vdso itself is not yet
(left and right zones shifting). Thus vdso_proxify
will complain that vdso is not yet mapped refusing
to restore.

Thus wait until everything is re-mapped then call
for proxification helper.

Reported: Mr. Jenkins
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

pie/restorer.c

@@ -728,15 +728,6 @@ long __export_restore_task(struct task_restore_args *args)
 		if (vma_remap(vma_premmaped_start(vma_entry),
 				vma_entry->start, vma_entry_len(vma_entry)))
 			goto core_restore_end;
-#ifdef CONFIG_VDSO
-		if (vma_entry_is(vma_entry, VMA_AREA_VDSO) ||
-		    vma_entry_is(vma_entry, VMA_AREA_VVAR)) {
-			if (vdso_proxify("left dumpee", &args->vdso_sym_rt,
-					 args->vdso_rt_parked_at,
-					 i, args->tgt_vmas, args->nr_vmas))
-				goto core_restore_end;
-		}
-#endif
 	}
 
 	/* Shift private vma-s to the right */
@@ -758,15 +749,6 @@ long __export_restore_task(struct task_restore_args *args)
 		if (vma_remap(vma_premmaped_start(vma_entry),
 				vma_entry->start, vma_entry_len(vma_entry)))
 			goto core_restore_end;
-#ifdef CONFIG_VDSO
-		if (vma_entry_is(vma_entry, VMA_AREA_VDSO) ||
-		    vma_entry_is(vma_entry, VMA_AREA_VVAR)) {
-			if (vdso_proxify("right dumpee", &args->vdso_sym_rt,
-					 args->vdso_rt_parked_at,
-					 i, args->tgt_vmas, args->nr_vmas))
-				goto core_restore_end;
-		}
-#endif
 	}
 
 	/*
@@ -789,6 +771,22 @@ long __export_restore_task(struct task_restore_args *args)
 		}
 	}
 
+#ifdef CONFIG_VDSO
+	/*
+	 * Proxify vDSO.
+	 */
+	for (i = 0; i < args->nr_vmas; i++) {
+		if (vma_entry_is(vma_entry, VMA_AREA_VDSO) ||
+		    vma_entry_is(vma_entry, VMA_AREA_VVAR)) {
+			if (vdso_proxify("dumpee", &args->vdso_sym_rt,
+					 args->vdso_rt_parked_at,
+					 i, args->tgt_vmas, args->nr_vmas))
+				goto core_restore_end;
+			break;
+		}
+	}
+#endif
+
 	/*
 	 * Walk though all VMAs again to drop PROT_WRITE
 	 * if it was not there.