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 | 51 ++++++++++++++++++++++++++++-------------
1 files changed, 35 insertions(+), 16 deletions(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 56b7cfa..4d55f0f 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -221,7 +221,7 @@ static inline bool is_control(u32 flags)
}
static ssize_t send_buf(struct port *port, const char *in_buf, size_t in_count,
- u32 flags)
+ u32 flags, bool from_user)
{
struct scatterlist sg[1];
struct virtio_console_header header;
@@ -265,15 +265,21 @@ static ssize_t send_buf(struct port *port, const char *in_buf, size_t in_count,
memcpy(buf->buf, &header, header_len);
copy_size -= header_len;
}
- /*
- * 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 + header_len, in_buf + in_offset, copy_size);
-
- buf->len = header_len + copy_size;
+ if (from_user) {
+ ret = copy_from_user(buf->buf + header_len,
+ in_buf + in_offset, copy_size);
+ } 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 + header_len,
+ in_buf + in_offset, copy_size);
+ ret = 0; /* Emulate copy_from_user behaviour */
+ }
+ buf->len = header_len + copy_size - ret;
sg_init_one(sg, buf->buf, buf->len);
spin_lock_irqsave(&port->portdev->write_list_lock, irqf);
@@ -306,14 +312,15 @@ static ssize_t send_control_msg(struct port *port, unsigned int event,
cpkt.event = event;
cpkt.value = value;
return send_buf(port, (char *)&cpkt, sizeof(cpkt),
- VIRTIO_CONSOLE_HDR_CONTROL);
+ VIRTIO_CONSOLE_HDR_CONTROL, false);
}
/*
* Give out the data that's requested from the buffers 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, *buf2;
ssize_t out_offset, ret;
@@ -324,6 +331,8 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count)
* Not taking the port->readbuf_list_lock here relying on the
* fact that buffers are taken out from the list only in this
* function so buf2 should be available all the time.
+ *
+ * Also, copy_to_user() might sleep.
*/
list_for_each_entry_safe(buf, buf2, &port->readbuf_head, list) {
size_t copy_size;
@@ -332,10 +341,20 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count)
if (copy_size > buf->len - buf->offset)
copy_size = buf->len - buf->offset;
- memcpy(out_buf + out_offset, buf->buf + buf->offset, copy_size);
+ if (to_user) {
+ ret = copy_to_user(out_buf + out_offset,
+ buf->buf + buf->offset,
+ copy_size);
+ /* FIXME: Deal with ret != 0 */
+ } else {
+ memcpy(out_buf + out_offset,
+ buf->buf + buf->offset,
+ copy_size);
+ ret = 0; /* Emulate copy_to_user behaviour */
+ }
/* Return the number of bytes actually copied */
- ret = copy_size;
+ ret = copy_size - ret;
buf->offset += ret;
out_offset += ret;
out_count -= ret;
@@ -373,7 +392,7 @@ 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, 0);
+ return send_buf(port, buf, count, 0, false);
}
/*
@@ -397,7 +416,7 @@ static int get_chars(u32 vtermno, char *buf, int count)
if (list_empty(&port->readbuf_head))
return 0;
- 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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