virtio: console: Prepare for writing to userspace buffers
When ports get advertised as char devices, the buffers will come from
userspace. Equip the fill_readbuf function with the ability to write
to userspace buffers.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index a70f2b3..8e447e1 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -358,7 +358,8 @@
* Give out the data that's requested from the buffer that we have
* queued up.
*/
-static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count)
+static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count,
+ bool to_user)
{
struct port_buffer *buf;
unsigned long flags;
@@ -367,12 +368,18 @@
return 0;
buf = port->inbuf;
- if (out_count > buf->len - buf->offset)
- out_count = buf->len - buf->offset;
+ out_count = min(out_count, buf->len - buf->offset);
- memcpy(out_buf, buf->buf + buf->offset, out_count);
+ if (to_user) {
+ ssize_t ret;
- /* Return the number of bytes actually copied */
+ ret = copy_to_user(out_buf, buf->buf + buf->offset, out_count);
+ if (ret)
+ return -EFAULT;
+ } else {
+ memcpy(out_buf, buf->buf + buf->offset, out_count);
+ }
+
buf->offset += out_count;
if (buf->offset == buf->len) {
@@ -388,6 +395,7 @@
spin_unlock_irqrestore(&port->inbuf_lock, flags);
}
+ /* Return the number of bytes actually copied */
return out_count;
}
@@ -431,7 +439,7 @@
/* If we don't have an input queue yet, we can't get input. */
BUG_ON(!port->in_vq);
- return fill_readbuf(port, buf, count);
+ return fill_readbuf(port, buf, count, false);
}
static void resize_console(struct port *port)