diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platforms/cell/spufs/file.c
index 514a1d508035..b4d38cb65f17 100644
--- a/arch/powerpc/platforms/cell/spufs/file.c
+++ b/arch/powerpc/platforms/cell/spufs/file.c
@@ -354,27 +354,54 @@ static int spufs_pipe_open(struct inode *inode, struct file *file)
 	return nonseekable_open(inode, file);
 }
 
+/*
+ * Read as many bytes from the mailbox as possible, until
+ * one of the conditions becomes true:
+ *
+ * - no more data available in the mailbox
+ * - end of the user provided buffer
+ * - end of the mapped area
+ */
 static ssize_t spufs_mbox_read(struct file *file, char __user *buf,
 			size_t len, loff_t *pos)
 {
 	struct spu_context *ctx = file->private_data;
-	u32 mbox_data;
-	int ret;
+	u32 mbox_data, __user *udata;
+	ssize_t count;
 
 	if (len < 4)
 		return -EINVAL;
 
-	spu_acquire(ctx);
-	ret = ctx->ops->mbox_read(ctx, &mbox_data);
-	spu_release(ctx);
-
-	if (!ret)
-		return -EAGAIN;
-
-	if (copy_to_user(buf, &mbox_data, sizeof mbox_data))
+	if (!access_ok(VERIFY_WRITE, buf, len))
 		return -EFAULT;
 
-	return 4;
+	udata = (void __user *)buf;
+
+	spu_acquire(ctx);
+	for (count = 0; count <= len; count += 4, udata++) {
+		int ret;
+		ret = ctx->ops->mbox_read(ctx, &mbox_data);
+		if (ret == 0)
+			break;
+
+		/*
+		 * at the end of the mapped area, we can fault
+		 * but still need to return the data we have
+		 * read successfully so far.
+		 */
+		ret = __put_user(mbox_data, udata);
+		if (ret) {
+			if (!count)
+				count = -EFAULT;
+			break;
+		}
+	}
+	spu_release(ctx);
+
+	if (!count)
+		count = -EAGAIN;
+
+	return count;
 }
 
 static struct file_operations spufs_mbox_fops = {
@@ -430,36 +457,70 @@ void spufs_ibox_callback(struct spu *spu)
 	kill_fasync(&ctx->ibox_fasync, SIGIO, POLLIN);
 }
 
+/*
+ * Read as many bytes from the interrupt mailbox as possible, until
+ * one of the conditions becomes true:
+ *
+ * - no more data available in the mailbox
+ * - end of the user provided buffer
+ * - end of the mapped area
+ *
+ * If the file is opened without O_NONBLOCK, we wait here until
+ * any data is available, but return when we have been able to
+ * read something.
+ */
 static ssize_t spufs_ibox_read(struct file *file, char __user *buf,
 			size_t len, loff_t *pos)
 {
 	struct spu_context *ctx = file->private_data;
-	u32 ibox_data;
-	ssize_t ret;
+	u32 ibox_data, __user *udata;
+	ssize_t count;
 
 	if (len < 4)
 		return -EINVAL;
 
+	if (!access_ok(VERIFY_WRITE, buf, len))
+		return -EFAULT;
+
+	udata = (void __user *)buf;
+
 	spu_acquire(ctx);
 
-	ret = 0;
+	/* wait only for the first element */
+	count = 0;
 	if (file->f_flags & O_NONBLOCK) {
 		if (!spu_ibox_read(ctx, &ibox_data))
-			ret = -EAGAIN;
+			count = -EAGAIN;
 	} else {
-		ret = spufs_wait(ctx->ibox_wq, spu_ibox_read(ctx, &ibox_data));
+		count = spufs_wait(ctx->ibox_wq, spu_ibox_read(ctx, &ibox_data));
+	}
+	if (count)
+		goto out;
+
+	/* if we can't write at all, return -EFAULT */
+	count = __put_user(ibox_data, udata);
+	if (count)
+		goto out;
+
+	for (count = 4, udata++; (count + 4) <= len; count += 4, udata++) {
+		int ret;
+		ret = ctx->ops->ibox_read(ctx, &ibox_data);
+		if (ret == 0)
+			break;
+		/*
+		 * at the end of the mapped area, we can fault
+		 * but still need to return the data we have
+		 * read successfully so far.
+		 */
+		ret = __put_user(ibox_data, udata);
+		if (ret)
+			break;
 	}
 
+out:
 	spu_release(ctx);
 
-	if (ret)
-		return ret;
-
-	ret = 4;
-	if (copy_to_user(buf, &ibox_data, sizeof ibox_data))
-		ret = -EFAULT;
-
-	return ret;
+	return count;
 }
 
 static unsigned int spufs_ibox_poll(struct file *file, poll_table *wait)
@@ -532,32 +593,67 @@ void spufs_wbox_callback(struct spu *spu)
 	kill_fasync(&ctx->wbox_fasync, SIGIO, POLLOUT);
 }
 
+/*
+ * Write as many bytes to the interrupt mailbox as possible, until
+ * one of the conditions becomes true:
+ *
+ * - the mailbox is full
+ * - end of the user provided buffer
+ * - end of the mapped area
+ *
+ * If the file is opened without O_NONBLOCK, we wait here until
+ * space is availabyl, but return when we have been able to
+ * write something.
+ */
 static ssize_t spufs_wbox_write(struct file *file, const char __user *buf,
 			size_t len, loff_t *pos)
 {
 	struct spu_context *ctx = file->private_data;
-	u32 wbox_data;
-	int ret;
+	u32 wbox_data, __user *udata;
+	ssize_t count;
 
 	if (len < 4)
 		return -EINVAL;
 
-	if (copy_from_user(&wbox_data, buf, sizeof wbox_data))
+	udata = (void __user *)buf;
+	if (!access_ok(VERIFY_READ, buf, len))
+		return -EFAULT;
+
+	if (__get_user(wbox_data, udata))
 		return -EFAULT;
 
 	spu_acquire(ctx);
 
-	ret = 0;
+	/*
+	 * make sure we can at least write one element, by waiting
+	 * in case of !O_NONBLOCK
+	 */
+	count = 0;
 	if (file->f_flags & O_NONBLOCK) {
 		if (!spu_wbox_write(ctx, wbox_data))
-			ret = -EAGAIN;
+			count = -EAGAIN;
 	} else {
-		ret = spufs_wait(ctx->wbox_wq, spu_wbox_write(ctx, wbox_data));
+		count = spufs_wait(ctx->wbox_wq, spu_wbox_write(ctx, wbox_data));
 	}
 
-	spu_release(ctx);
+	if (count)
+		goto out;
 
-	return ret ? ret : sizeof wbox_data;
+	/* write aѕ much as possible */
+	for (count = 4, udata++; (count + 4) <= len; count += 4, udata++) {
+		int ret;
+		ret = __get_user(wbox_data, udata);
+		if (ret)
+			break;
+
+		ret = spu_wbox_write(ctx, wbox_data);
+		if (ret == 0)
+			break;
+	}
+
+out:
+	spu_release(ctx);
+	return count;
 }
 
 static unsigned int spufs_wbox_poll(struct file *file, poll_table *wait)