2 files changed, 203 insertions, 25 deletions

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 13a4b9f..39da166 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -50,6 +50,7 @@
 #include <linux/user_namespace.h>
 #include <linux/scatterlist.h>
 #include <linux/uaccess.h>
+#include <linux/dma-mapping.h>
 #include <asm/byteorder.h>
 #include <linux/moduleparam.h>
 
@@ -69,6 +70,7 @@ struct usb_dev_state {
 	spinlock_t lock;            /* protects the async urb lists */
 	struct list_head async_pending;
 	struct list_head async_completed;
+	struct list_head memory_list;
 	wait_queue_head_t wait;     /* wake up if a request completed */
 	unsigned int discsignr;
 	struct pid *disc_pid;
@@ -79,6 +81,17 @@ struct usb_dev_state {
 	u32 disabled_bulk_eps;
 };
 
+struct usb_memory {
+	struct list_head memlist;
+	int vma_use_count;
+	int urb_use_count;
+	u32 size;
+	void *mem;
+	dma_addr_t dma_handle;
+	unsigned long vm_start;
+	struct usb_dev_state *ps;
+};
+
 struct async {
 	struct list_head asynclist;
 	struct usb_dev_state *ps;
@@ -89,6 +102,7 @@ struct async {
 	void __user *userbuffer;
 	void __user *userurb;
 	struct urb *urb;
+	struct usb_memory *usbm;
 	unsigned int mem_usage;
 	int status;
 	u32 secid;
@@ -162,6 +176,111 @@ static int connected(struct usb_dev_state *ps)
 			ps->dev->state != USB_STATE_NOTATTACHED);
 }
 
+static void dec_usb_memory_use_count(struct usb_memory *usbm, int *count)
+{
+	struct usb_dev_state *ps = usbm->ps;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ps->lock, flags);
+	--*count;
+	if (usbm->urb_use_count == 0 && usbm->vma_use_count == 0) {
+		list_del(&usbm->memlist);
+		spin_unlock_irqrestore(&ps->lock, flags);
+
+		usb_free_coherent(ps->dev, usbm->size, usbm->mem,
+				usbm->dma_handle);
+		usbfs_decrease_memory_usage(
+			usbm->size + sizeof(struct usb_memory));
+		kfree(usbm);
+	} else {
+		spin_unlock_irqrestore(&ps->lock, flags);
+	}
+}
+
+static void usbdev_vm_open(struct vm_area_struct *vma)
+{
+	struct usb_memory *usbm = vma->vm_private_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&usbm->ps->lock, flags);
+	++usbm->vma_use_count;
+	spin_unlock_irqrestore(&usbm->ps->lock, flags);
+}
+
+static void usbdev_vm_close(struct vm_area_struct *vma)
+{
+	struct usb_memory *usbm = vma->vm_private_data;
+
+	dec_usb_memory_use_count(usbm, &usbm->vma_use_count);
+}
+
+struct vm_operations_struct usbdev_vm_ops = {
+	.open = usbdev_vm_open,
+	.close = usbdev_vm_close
+};
+
+static int usbdev_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct usb_memory *usbm = NULL;
+	struct usb_dev_state *ps = file->private_data;
+	size_t size = vma->vm_end - vma->vm_start;
+	void *mem;
+	unsigned long flags;
+	dma_addr_t dma_handle;
+	int ret;
+
+	ret = usbfs_increase_memory_usage(size + sizeof(struct usb_memory));
+	if (ret)
+		goto error;
+
+	usbm = kzalloc(sizeof(struct usb_memory), GFP_KERNEL);
+	if (!usbm) {
+		ret = -ENOMEM;
+		goto error_decrease_mem;
+	}
+
+	mem = usb_alloc_coherent(ps->dev, size, GFP_USER, &dma_handle);
+	if (!mem) {
+		ret = -ENOMEM;
+		goto error_free_usbm;
+	}
+
+	memset(mem, 0, size);
+
+	usbm->mem = mem;
+	usbm->dma_handle = dma_handle;
+	usbm->size = size;
+	usbm->ps = ps;
+	usbm->vm_start = vma->vm_start;
+	usbm->vma_use_count = 1;
+	INIT_LIST_HEAD(&usbm->memlist);
+
+	if (remap_pfn_range(vma, vma->vm_start,
+			virt_to_phys(usbm->mem) >> PAGE_SHIFT,
+			size, vma->vm_page_prot) < 0) {
+		dec_usb_memory_use_count(usbm, &usbm->vma_use_count);
+		return -EAGAIN;
+	}
+
+	vma->vm_flags |= VM_IO;
+	vma->vm_flags |= (VM_DONTEXPAND | VM_DONTDUMP);
+	vma->vm_ops = &usbdev_vm_ops;
+	vma->vm_private_data = usbm;
+
+	spin_lock_irqsave(&ps->lock, flags);
+	list_add_tail(&usbm->memlist, &ps->memory_list);
+	spin_unlock_irqrestore(&ps->lock, flags);
+
+	return 0;
+
+error_free_usbm:
+	kfree(usbm);
+error_decrease_mem:
+	usbfs_decrease_memory_usage(size + sizeof(struct usb_memory));
+error:
+	return ret;
+}
+
 static ssize_t usbdev_read(struct file *file, char __user *buf, size_t nbytes,
 			   loff_t *ppos)
 {
@@ -278,8 +397,13 @@ static void free_async(struct async *as)
 		if (sg_page(&as->urb->sg[i]))
 			kfree(sg_virt(&as->urb->sg[i]));
 	}
+
 	kfree(as->urb->sg);
-	kfree(as->urb->transfer_buffer);
+	if (as->usbm == NULL)
+		kfree(as->urb->transfer_buffer);
+	else
+		dec_usb_memory_use_count(as->usbm, &as->usbm->urb_use_count);
+
 	kfree(as->urb->setup_packet);
 	usb_free_urb(as->urb);
 	usbfs_decrease_memory_usage(as->mem_usage);
@@ -893,6 +1017,7 @@ static int usbdev_open(struct inode *inode, struct file *file)
 	INIT_LIST_HEAD(&ps->list);
 	INIT_LIST_HEAD(&ps->async_pending);
 	INIT_LIST_HEAD(&ps->async_completed);
+	INIT_LIST_HEAD(&ps->memory_list);
 	init_waitqueue_head(&ps->wait);
 	ps->discsignr = 0;
 	ps->disc_pid = get_pid(task_pid(current));
@@ -945,6 +1070,7 @@ static int usbdev_release(struct inode *inode, struct file *file)
 		free_async(as);
 		as = async_getcompleted(ps);
 	}
+
 	kfree(ps);
 	return 0;
 }
@@ -1266,6 +1392,31 @@ static int proc_setconfig(struct usb_dev_state *ps, void __user *arg)
 	return status;
 }
 
+static struct usb_memory *
+find_memory_area(struct usb_dev_state *ps, const struct usbdevfs_urb *uurb)
+{
+	struct usb_memory *usbm = NULL, *iter;
+	unsigned long flags;
+	unsigned long uurb_start = (unsigned long)uurb->buffer;
+
+	spin_lock_irqsave(&ps->lock, flags);
+	list_for_each_entry(iter, &ps->memory_list, memlist) {
+		if (uurb_start >= iter->vm_start &&
+				uurb_start < iter->vm_start + iter->size) {
+			if (uurb->buffer_length > iter->vm_start + iter->size -
+					uurb_start) {
+				usbm = ERR_PTR(-EINVAL);
+			} else {
+				usbm = iter;
+				usbm->urb_use_count++;
+			}
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&ps->lock, flags);
+	return usbm;
+}
+
 static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb,
 			struct usbdevfs_iso_packet_desc __user *iso_frame_desc,
 			void __user *arg)
@@ -1421,6 +1572,19 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
 		goto error;
 	}
 
+	as->usbm = find_memory_area(ps, uurb);
+	if (IS_ERR(as->usbm)) {
+		ret = PTR_ERR(as->usbm);
+		as->usbm = NULL;
+		goto error;
+	}
+
+	/* do not use SG buffers when memory mapped segments
+	 * are in use
+	 */
+	if (as->usbm)
+		num_sgs = 0;
+
 	u += sizeof(struct async) + sizeof(struct urb) + uurb->buffer_length +
 	     num_sgs * sizeof(struct scatterlist);
 	ret = usbfs_increase_memory_usage(u);
@@ -1458,29 +1622,35 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
 			totlen -= u;
 		}
 	} else if (uurb->buffer_length > 0) {
-		as->urb->transfer_buffer = kmalloc(uurb->buffer_length,
-				GFP_KERNEL);
-		if (!as->urb->transfer_buffer) {
-			ret = -ENOMEM;
-			goto error;
-		}
+		if (as->usbm) {
+			unsigned long uurb_start = (unsigned long)uurb->buffer;
 
-		if (!is_in) {
-			if (copy_from_user(as->urb->transfer_buffer,
-					   uurb->buffer,
-					   uurb->buffer_length)) {
-				ret = -EFAULT;
+			as->urb->transfer_buffer = as->usbm->mem +
+					(uurb_start - as->usbm->vm_start);
+		} else {
+			as->urb->transfer_buffer = kmalloc(uurb->buffer_length,
+					GFP_KERNEL);
+			if (!as->urb->transfer_buffer) {
+				ret = -ENOMEM;
 				goto error;
 			}
-		} else if (uurb->type == USBDEVFS_URB_TYPE_ISO) {
-			/*
-			 * Isochronous input data may end up being
-			 * discontiguous if some of the packets are short.
-			 * Clear the buffer so that the gaps don't leak
-			 * kernel data to userspace.
-			 */
-			memset(as->urb->transfer_buffer, 0,
-					uurb->buffer_length);
+			if (!is_in) {
+				if (copy_from_user(as->urb->transfer_buffer,
+						   uurb->buffer,
+						   uurb->buffer_length)) {
+					ret = -EFAULT;
+					goto error;
+				}
+			} else if (uurb->type == USBDEVFS_URB_TYPE_ISO) {
+				/*
+				 * Isochronous input data may end up being
+				 * discontiguous if some of the packets are
+				 * short. Clear the buffer so that the gaps
+				 * don't leak kernel data to userspace.
+				 */
+				memset(as->urb->transfer_buffer, 0,
+						uurb->buffer_length);
+			}
 		}
 	}
 	as->urb->dev = ps->dev;
@@ -1527,10 +1697,14 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
 	isopkt = NULL;
 	as->ps = ps;
 	as->userurb = arg;
-	if (is_in && uurb->buffer_length > 0)
+	if (as->usbm) {
+		unsigned long uurb_start = (unsigned long)uurb->buffer;
+
+		as->urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+		as->urb->transfer_dma = as->usbm->dma_handle +
+				(uurb_start - as->usbm->vm_start);
+	} else if (is_in && uurb->buffer_length > 0)
 		as->userbuffer = uurb->buffer;
-	else
-		as->userbuffer = NULL;
 	as->signr = uurb->signr;
 	as->ifnum = ifnum;
 	as->pid = get_pid(task_pid(current));
@@ -1586,6 +1760,8 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
 	return 0;
 
  error:
+	if (as && as->usbm)
+		dec_usb_memory_use_count(as->usbm, &as->usbm->urb_use_count);
 	kfree(isopkt);
 	kfree(dr);
 	if (as)
@@ -2039,7 +2215,7 @@ static int proc_get_capabilities(struct usb_dev_state *ps, void __user *arg)
 	__u32 caps;
 
 	caps = USBDEVFS_CAP_ZERO_PACKET | USBDEVFS_CAP_NO_PACKET_SIZE_LIM |
-			USBDEVFS_CAP_REAP_AFTER_DISCONNECT;
+			USBDEVFS_CAP_REAP_AFTER_DISCONNECT | USBDEVFS_CAP_MMAP;
 	if (!ps->dev->bus->no_stop_on_short)
 		caps |= USBDEVFS_CAP_BULK_CONTINUATION;
 	if (ps->dev->bus->sg_tablesize)
@@ -2365,6 +2541,7 @@ const struct file_operations usbdev_file_operations = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl =   usbdev_compat_ioctl,
 #endif
+	.mmap =           usbdev_mmap,
 	.open =		  usbdev_open,
 	.release =	  usbdev_release,
 };
diff --git a/include/uapi/linux/usbdevice_fs.h b/include/uapi/linux/usbdevice_fs.h
index 019ba1e..ecbd176 100644
--- a/include/uapi/linux/usbdevice_fs.h
+++ b/include/uapi/linux/usbdevice_fs.h
@@ -134,6 +134,7 @@ struct usbdevfs_hub_portinfo {
 #define USBDEVFS_CAP_NO_PACKET_SIZE_LIM		0x04
 #define USBDEVFS_CAP_BULK_SCATTER_GATHER	0x08
 #define USBDEVFS_CAP_REAP_AFTER_DISCONNECT	0x10
+#define USBDEVFS_CAP_MMAP			0x20
 
 /* USBDEVFS_DISCONNECT_CLAIM flags & struct */