s390/hypfs: do not use stack buffers for hardware data

With CONFIG_VMAP_STACK=y the stack is allocated from the vmalloc space.
Data structures passed to a hardware or a hypervisor interface that
requires V=R can not be allocated on the stack anymore.

Use kmalloc to get memory for the hypsfs_diag304 structure.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/hypfs/hypfs_sprp.c

@@ -68,40 +68,44 @@ static int hypfs_sprp_create(void **data_ptr, void **free_ptr, size_t *size)
 
 static int __hypfs_sprp_ioctl(void __user *user_area)
 {
-	struct hypfs_diag304 diag304;
+	struct hypfs_diag304 *diag304;
 	unsigned long cmd;
 	void __user *udata;
 	void *data;
 	int rc;
 
-	if (copy_from_user(&diag304, user_area, sizeof(diag304)))
-		return -EFAULT;
-	if ((diag304.args[0] >> 8) != 0 || diag304.args[1] > DIAG304_CMD_MAX)
-		return -EINVAL;
-
+	rc = -ENOMEM;
 	data = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
-	if (!data)
-		return -ENOMEM;
+	diag304 = kzalloc(sizeof(*diag304), GFP_KERNEL);
+	if (!data || !diag304)
+		goto out;
 
-	udata = (void __user *)(unsigned long) diag304.data;
-	if (diag304.args[1] == DIAG304_SET_WEIGHTS ||
-	    diag304.args[1] == DIAG304_SET_CAPPING)
-		if (copy_from_user(data, udata, PAGE_SIZE)) {
 	rc = -EFAULT;
+	if (copy_from_user(diag304, user_area, sizeof(*diag304)))
+		goto out;
+	rc = -EINVAL;
+	if ((diag304->args[0] >> 8) != 0 || diag304->args[1] > DIAG304_CMD_MAX)
+		goto out;
+
+	rc = -EFAULT;
+	udata = (void __user *)(unsigned long) diag304->data;
+	if (diag304->args[1] == DIAG304_SET_WEIGHTS ||
+	    diag304->args[1] == DIAG304_SET_CAPPING)
+		if (copy_from_user(data, udata, PAGE_SIZE))
 			goto out;
-		}
 
-	cmd = *(unsigned long *) &diag304.args[0];
-	diag304.rc = hypfs_sprp_diag304(data, cmd);
+	cmd = *(unsigned long *) &diag304->args[0];
+	diag304->rc = hypfs_sprp_diag304(data, cmd);
 
-	if (diag304.args[1] == DIAG304_QUERY_PRP)
+	if (diag304->args[1] == DIAG304_QUERY_PRP)
 		if (copy_to_user(udata, data, PAGE_SIZE)) {
 			rc = -EFAULT;
 			goto out;
 		}
 
-	rc = copy_to_user(user_area, &diag304, sizeof(diag304)) ? -EFAULT : 0;
+	rc = copy_to_user(user_area, diag304, sizeof(*diag304)) ? -EFAULT : 0;
 out:
+	kfree(diag304);
 	free_page((unsigned long) data);
 	return rc;
 }