xen/24171-x86waitqueue_Allocate_whole_page_for_shadow_stack..patch

changeset:   24171:fe80909663c1
user:        Keir Fraser <keir@xen.org>
date:        Tue Nov 22 13:00:21 2011 +0000
files:       xen/common/wait.c
description:
x86,waitqueue: Allocate whole page for shadow stack.

Signed-off-by: Keir Fraser <keir@xen.org>


---
 xen/common/wait.c |   16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

Index: xen-4.1.2-testing/xen/common/wait.c
===================================================================
--- xen-4.1.2-testing.orig/xen/common/wait.c
+++ xen-4.1.2-testing/xen/common/wait.c
@@ -33,7 +33,7 @@ struct waitqueue_vcpu {
      * hypervisor context before sleeping (descheduling), setjmp/longjmp-style.
      */
     void *esp;
-    char stack[3000];
+    char *stack;
 #endif
 };
 
@@ -45,6 +45,15 @@ int init_waitqueue_vcpu(struct vcpu *v)
     if ( wqv == NULL )
         return -ENOMEM;
 
+#ifdef CONFIG_X86
+    wqv->stack = alloc_xenheap_page();
+    if ( wqv->stack == NULL )
+    {
+        xfree(wqv);
+        return -ENOMEM;
+    }
+#endif
+
     memset(wqv, 0, sizeof(*wqv));
     INIT_LIST_HEAD(&wqv->list);
     wqv->vcpu = v;
@@ -63,6 +72,9 @@ void destroy_waitqueue_vcpu(struct vcpu
         return;
 
     BUG_ON(!list_empty(&wqv->list));
+#ifdef CONFIG_X86
+    free_xenheap_page(wqv->stack);
+#endif
     xfree(wqv);
 
     v->waitqueue_vcpu = NULL;
@@ -115,7 +127,7 @@ static void __prepare_to_wait(struct wai
         : "=S" (wqv->esp)
         : "c" (cpu_info), "D" (wqv->stack)
         : "memory" );
-    BUG_ON((cpu_info - (char *)wqv->esp) > sizeof(wqv->stack));
+    BUG_ON((cpu_info - (char *)wqv->esp) > PAGE_SIZE);
 }
 
 static void __finish_wait(struct waitqueue_vcpu *wqv)