staging: android: ion: Add ioctl to query available heaps

Ion clients currently lack a good method to determine what
heaps are available and what ids they map to. This leads
to tight coupling between user and kernel space and headaches.
Add a query ioctl to let userspace know the availability of
heaps.

Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 89 insertions, 10 deletions

diff --git a/drivers/staging/android/ion/ion-ioctl.c b/drivers/staging/android/ion/ion-ioctl.c
index 341ba7d83403..7e7431d8d49f 100644
--- a/drivers/staging/android/ion/ion-ioctl.c
+++ b/drivers/staging/android/ion/ion-ioctl.c
@@ -22,6 +22,31 @@
 #include "ion_priv.h"
 #include "compat_ion.h"
 
+union ion_ioctl_arg {
+	struct ion_fd_data fd;
+	struct ion_allocation_data allocation;
+	struct ion_handle_data handle;
+	struct ion_custom_data custom;
+	struct ion_heap_query query;
+};
+
+static int validate_ioctl_arg(unsigned int cmd, union ion_ioctl_arg *arg)
+{
+	int ret = 0;
+
+	switch (cmd) {
+	case ION_IOC_HEAP_QUERY:
+		ret = arg->query.reserved0 != 0;
+		ret |= arg->query.reserved1 != 0;
+		ret |= arg->query.reserved2 != 0;
+		break;
+	default:
+		break;
+	}
+
+	return ret ? -EINVAL : 0;
+}
+
 /* fix up the cases where the ioctl direction bits are incorrect */
 static unsigned int ion_ioctl_dir(unsigned int cmd)
 {
@@ -42,22 +67,27 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	struct ion_handle *cleanup_handle = NULL;
 	int ret = 0;
 	unsigned int dir;
-
-	union {
-		struct ion_fd_data fd;
-		struct ion_allocation_data allocation;
-		struct ion_handle_data handle;
-		struct ion_custom_data custom;
-	} data;
+	union ion_ioctl_arg data;
 
 	dir = ion_ioctl_dir(cmd);
 
 	if (_IOC_SIZE(cmd) > sizeof(data))
 		return -EINVAL;
 
-	if (dir & _IOC_WRITE)
-		if (copy_from_user(&data, (void __user *)arg, _IOC_SIZE(cmd)))
-			return -EFAULT;
+	/*
+	 * The copy_from_user is unconditional here for both read and write
+	 * to do the validate. If there is no write for the ioctl, the
+	 * buffer is cleared
+	 */
+	if (copy_from_user(&data, (void __user *)arg, _IOC_SIZE(cmd)))
+		return -EFAULT;
+
+	ret = validate_ioctl_arg(cmd, &data);
+	if (WARN_ON_ONCE(ret))
+		return ret;
+
+	if (!(dir & _IOC_WRITE))
+		memset(&data, 0, sizeof(data));
 
 	switch (cmd) {
 	case ION_IOC_ALLOC:
@@ -129,6 +159,9 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 						data.custom.arg);
 		break;
 	}
+	case ION_IOC_HEAP_QUERY:
+		ret = ion_query_heaps(client, &data.query);
+		break;
 	default:
 		return -ENOTTY;
 	}
diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index a92804f434cb..396ded52ab70 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -1159,6 +1159,48 @@ int ion_sync_for_device(struct ion_client *client, int fd)
 	return 0;
 }
 
+int ion_query_heaps(struct ion_client *client, struct ion_heap_query *query)
+{
+	struct ion_device *dev = client->dev;
+	struct ion_heap_data __user *buffer = u64_to_user_ptr(query->heaps);
+	int ret = -EINVAL, cnt = 0, max_cnt;
+	struct ion_heap *heap;
+	struct ion_heap_data hdata;
+
+	memset(&hdata, 0, sizeof(hdata));
+
+	down_read(&dev->lock);
+	if (!buffer) {
+		query->cnt = dev->heap_cnt;
+		ret = 0;
+		goto out;
+	}
+
+	if (query->cnt <= 0)
+		goto out;
+
+	max_cnt = query->cnt;
+
+	plist_for_each_entry(heap, &dev->heaps, node) {
+		strncpy(hdata.name, heap->name, MAX_HEAP_NAME);
+		hdata.name[sizeof(hdata.name) - 1] = '\0';
+		hdata.type = heap->type;
+		hdata.heap_id = heap->id;
+
+		ret = copy_to_user(&buffer[cnt],
+				   &hdata, sizeof(hdata));
+
+		cnt++;
+		if (cnt >= max_cnt)
+			break;
+	}
+
+	query->cnt = cnt;
+out:
+	up_read(&dev->lock);
+	return ret;
+}
+
 static int ion_release(struct inode *inode, struct file *file)
 {
 	struct ion_client *client = file->private_data;
@@ -1376,6 +1418,7 @@ void ion_device_add_heap(struct ion_device *dev, struct ion_heap *heap)
 		}
 	}
 
+	dev->heap_cnt++;
 	up_write(&dev->lock);
 }
 EXPORT_SYMBOL(ion_device_add_heap);
diff --git a/drivers/staging/android/ion/ion_priv.h b/drivers/staging/android/ion/ion_priv.h
index 4a78fab80137..3c3b3245275d 100644
--- a/drivers/staging/android/ion/ion_priv.h
+++ b/drivers/staging/android/ion/ion_priv.h
@@ -102,6 +102,7 @@ struct ion_device {
 	struct dentry *debug_root;
 	struct dentry *heaps_debug_root;
 	struct dentry *clients_debug_root;
+	int heap_cnt;
 };
 
 /**
@@ -467,4 +468,6 @@ struct ion_handle *ion_handle_get_by_id(struct ion_client *client,
 
 int ion_handle_put(struct ion_handle *handle);
 
+int ion_query_heaps(struct ion_client *client, struct ion_heap_query *query);
+
 #endif /* _ION_PRIV_H */