1 files changed, 41 insertions, 18 deletions

diff --git a/arch/s390/lib/uaccess_pt.c b/arch/s390/lib/uaccess_pt.c
index 5efdfe9f5e7..d66215b0fde 100644
--- a/arch/s390/lib/uaccess_pt.c
+++ b/arch/s390/lib/uaccess_pt.c
@@ -302,6 +302,10 @@ static size_t copy_in_user_pt(size_t n, void __user *to,
 	pte_t *pte_from, *pte_to;
 	int write_user;
 
+	if (segment_eq(get_fs(), KERNEL_DS)) {
+		memcpy((void __force *) to, (void __force *) from, n);
+		return 0;
+	}
 	done = 0;
 retry:
 	spin_lock(&mm->page_table_lock);
@@ -361,18 +365,10 @@ fault:
 		     : "0" (-EFAULT), "d" (oparg), "a" (uaddr),		\
 		       "m" (*uaddr) : "cc" );
 
-int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
+static int __futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
 {
 	int oldval = 0, newval, ret;
 
-	spin_lock(&current->mm->page_table_lock);
-	uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
-	if (!uaddr) {
-		spin_unlock(&current->mm->page_table_lock);
-		return -EFAULT;
-	}
-	get_page(virt_to_page(uaddr));
-	spin_unlock(&current->mm->page_table_lock);
 	switch (op) {
 	case FUTEX_OP_SET:
 		__futex_atomic_op("lr %2,%5\n",
@@ -397,17 +393,17 @@ int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
 	default:
 		ret = -ENOSYS;
 	}
-	put_page(virt_to_page(uaddr));
-	*old = oldval;
+	if (ret == 0)
+		*old = oldval;
 	return ret;
 }
 
-int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
+int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
 {
 	int ret;
 
-	if (!current->mm)
-		return -EFAULT;
+	if (segment_eq(get_fs(), KERNEL_DS))
+		return __futex_atomic_op_pt(op, uaddr, oparg, old);
 	spin_lock(&current->mm->page_table_lock);
 	uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
 	if (!uaddr) {
@@ -416,13 +412,40 @@ int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
 	}
 	get_page(virt_to_page(uaddr));
 	spin_unlock(&current->mm->page_table_lock);
-	asm volatile("   cs   %1,%4,0(%5)\n"
-		     "0: lr   %0,%1\n"
-		     "1:\n"
-		     EX_TABLE(0b,1b)
+	ret = __futex_atomic_op_pt(op, uaddr, oparg, old);
+	put_page(virt_to_page(uaddr));
+	return ret;
+}
+
+static int __futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
+{
+	int ret;
+
+	asm volatile("0: cs   %1,%4,0(%5)\n"
+		     "1: lr   %0,%1\n"
+		     "2:\n"
+		     EX_TABLE(0b,2b) EX_TABLE(1b,2b)
 		     : "=d" (ret), "+d" (oldval), "=m" (*uaddr)
 		     : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
 		     : "cc", "memory" );
+	return ret;
+}
+
+int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
+{
+	int ret;
+
+	if (segment_eq(get_fs(), KERNEL_DS))
+		return __futex_atomic_cmpxchg_pt(uaddr, oldval, newval);
+	spin_lock(&current->mm->page_table_lock);
+	uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
+	if (!uaddr) {
+		spin_unlock(&current->mm->page_table_lock);
+		return -EFAULT;
+	}
+	get_page(virt_to_page(uaddr));
+	spin_unlock(&current->mm->page_table_lock);
+	ret = __futex_atomic_cmpxchg_pt(uaddr, oldval, newval);
 	put_page(virt_to_page(uaddr));
 	return ret;
 }