When ports get advertised as char devices, the buffers will come from
userspace. Equip the send_buf and fill_readbuf functions with the
ability to write to / read from userspace buffers respectively.
Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx>
---
drivers/char/virtio_console.c | 45 ++++++++++++++++++++++++++--------------
1 files changed, 29 insertions(+), 16 deletions(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index c0bc146..35bdd41 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -332,7 +332,8 @@ static ssize_t send_control_msg(struct port *port, unsigned int event,
return 0;
}
-static ssize_t send_buf(struct port *port, const char *in_buf, size_t in_count)
+static ssize_t send_buf(struct port *port, const char *in_buf, size_t in_count,
+ bool from_user)
{
struct scatterlist sg[1];
struct virtqueue *out_vq;
@@ -357,15 +358,19 @@ static ssize_t send_buf(struct port *port, const char *in_buf, size_t in_count)
if (in_count > buf->size)
in_count = buf->size;
- /*
- * Since we're not sure when the host will actually
- * consume the data and tell us about it, we have to
- * copy the data here in case the caller frees the
- * in_buf.
- */
- memcpy(buf->buf, in_buf, in_count);
-
- buf->len = in_count;
+ if (from_user) {
+ ret = copy_from_user(buf->buf, in_buf, in_count);
+ } else {
+ /*
+ * Since we're not sure when the host will actually
+ * consume the data and tell us about it, we have to
+ * copy the data here in case the caller frees the
+ * in_buf.
+ */
+ memcpy(buf->buf, in_buf, in_count);
+ ret = 0; /* Emulate copy_from_user behaviour */
+ }
+ buf->len = in_count - ret;
sg_init_one(sg, buf->buf, buf->len);
ret = out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, buf);
@@ -384,9 +389,11 @@ static ssize_t send_buf(struct port *port, const char *in_buf, size_t in_count)
* 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;
+ ssize_t ret;
unsigned long flags;
if (!out_count || !port_has_data(port))
@@ -396,10 +403,16 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count)
if (out_count > buf->len - buf->offset)
out_count = buf->len - buf->offset;
- memcpy(out_buf, buf->buf + buf->offset, out_count);
+ if (to_user) {
+ ret = copy_to_user(out_buf, buf->buf + buf->offset, out_count);
+ } else {
+ memcpy(out_buf, buf->buf + buf->offset, out_count);
+ ret = 0; /* Emulate copy_to_user behaviour */
+ }
/* Return the number of bytes actually copied */
- buf->offset += out_count;
+ ret = out_count - ret;
+ buf->offset += ret;
if (buf->offset == buf->len) {
/*
@@ -414,7 +427,7 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count)
spin_unlock_irqrestore(&port->inbuf_lock, flags);
}
- return out_count;
+ return ret;
}
/*
@@ -436,7 +449,7 @@ static int put_chars(u32 vtermno, const char *buf, int count)
if (unlikely(early_put_chars))
return early_put_chars(vtermno, buf, count);
- return send_buf(port, buf, count);
+ return send_buf(port, buf, count, false);
}
/*
@@ -457,7 +470,7 @@ static int get_chars(u32 vtermno, char *buf, int count)
/* 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)
--
1.6.2.5
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