text: /**************************************************************************
   *
   * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
   * All Rights Reserved.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sub license, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice (including the
   * next paragraph) shall be included in all copies or substantial portions
   * of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
   * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
   * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
   * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
   * USE OR OTHER DEALINGS IN THE SOFTWARE.
   *
   **************************************************************************/
  /*
   * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
   */
  
  #include <ttm/ttm_module.h>
  #include <ttm/ttm_bo_driver.h>
  #include <ttm/ttm_placement.h>
  #include <linux/mm.h>
  #include <linux/rbtree.h>
  #include <linux/module.h>
  #include <linux/uaccess.h>
  
  #define TTM_BO_VM_NUM_PREFAULT 16
  
  static struct ttm_buffer_object *ttm_bo_vm_lookup_rb(struct ttm_bo_device *bdev,
  						     unsigned long page_start,
  						     unsigned long num_pages)
  {
  	struct rb_node *cur = bdev->addr_space_rb.rb_node;
  	unsigned long cur_offset;
  	struct ttm_buffer_object *bo;
  	struct ttm_buffer_object *best_bo = NULL;
  
  	while (likely(cur != NULL)) {
  		bo = rb_entry(cur, struct ttm_buffer_object, vm_rb);
  		cur_offset = bo->vm_node->start;
  		if (page_start >= cur_offset) {
  			cur = cur->rb_right;
  			best_bo = bo;
  			if (page_start == cur_offset)
  				break;
  		} else
  			cur = cur->rb_left;
  	}
  
  	if (unlikely(best_bo == NULL))
  		return NULL;
  
  	if (unlikely((best_bo->vm_node->start + best_bo->num_pages) <
  		     (page_start + num_pages)))
  		return NULL;
  
  	return best_bo;
  }
  
  static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
  {
  	struct ttm_buffer_object *bo = (struct ttm_buffer_object *)
  	    vma->vm_private_data;
  	struct ttm_bo_device *bdev = bo->bdev;
  	unsigned long bus_base;
  	unsigned long bus_offset;
  	unsigned long bus_size;
  	unsigned long page_offset;
  	unsigned long page_last;
  	unsigned long pfn;
  	struct ttm_tt *ttm = NULL;
  	struct page *page;
  	int ret;
  	int i;
  	bool is_iomem;
  	unsigned long address = (unsigned long)vmf->virtual_address;
  	int retval = VM_FAULT_NOPAGE;
  
  	/*
  	 * Work around locking order reversal in fault / nopfn
  	 * between mmap_sem and bo_reserve: Perform a trylock operation
  	 * for reserve, and if it fails, retry the fault after scheduling.
  	 */
  
  	ret = ttm_bo_reserve(bo, true, true, false, 0);
  	if (unlikely(ret != 0)) {
  		if (ret == -EBUSY)
  			set_need_resched();
  		return VM_FAULT_NOPAGE;
  	}
  
  	if (bdev->driver->fault_reserve_notify)
  		bdev->driver->fault_reserve_notify(bo);
  
  	/*
  	 * Wait for buffer data in transit, due to a pipelined
  	 * move.
  	 */
  
  	spin_lock(&bo->lock);
  	if (test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)) {
  		ret = ttm_bo_wait(bo, false, true, false);
  		spin_unlock(&bo->lock);
  		if (unlikely(ret != 0)) {
  			retval = (ret != -ERESTARTSYS) ?
  			    VM_FAULT_SIGBUS : VM_FAULT_NOPAGE;
  			goto out_unlock;
  		}
  	} else
  		spin_unlock(&bo->lock);
  
  
  	ret = ttm_bo_pci_offset(bdev, &bo->mem, &bus_base, &bus_offset,
  				&bus_size);
  	if (unlikely(ret != 0)) {
  		retval = VM_FAULT_SIGBUS;
  		goto out_unlock;
  	}
  
  	is_iomem = (bus_size != 0);
  
  	page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
  	    bo->vm_node->start - vma->vm_pgoff;
  	page_last = ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) +
  	    bo->vm_node->start - vma->vm_pgoff;
  
  	if (unlikely(page_offset >= bo->num_pages)) {
  		retval = VM_FAULT_SIGBUS;
  		goto out_unlock;
  	}
  
  	/*
  	 * Strictly, we're not allowed to modify vma->vm_page_prot here,
  	 * since the mmap_sem is only held in read mode. However, we
  	 * modify only the caching bits of vma->vm_page_prot and
  	 * consider those bits protected by
  	 * the bo->mutex, as we should be the only writers.
  	 * There shouldn't really be any readers of these bits except
  	 * within vm_insert_mixed()? fork?
  	 *
  	 * TODO: Add a list of vmas to the bo, and change the
  	 * vma->vm_page_prot when the object changes caching policy, with
  	 * the correct locks held.
  	 */
  
  	if (is_iomem) {
  		vma->vm_page_prot = ttm_io_prot(bo->mem.placement,
  						vma->vm_page_prot);
  	} else {
  		ttm = bo->ttm;
  		vma->vm_page_prot = (bo->mem.placement & TTM_PL_FLAG_CACHED) ?
  		    vm_get_page_prot(vma->vm_flags) :
  		    ttm_io_prot(bo->mem.placement, vma->vm_page_prot);
  	}
  
  	/*
  	 * Speculatively prefault a number of pages. Only error on
  	 * first page.
  	 */
  
  	for (i = 0; i < TTM_BO_VM_NUM_PREFAULT; ++i) {
  
  		if (is_iomem)
  			pfn = ((bus_base + bus_offset) >> PAGE_SHIFT) +
  			    page_offset;
  		else {
  			page = ttm_tt_get_page(ttm, page_offset);
  			if (unlikely(!page && i == 0)) {
  				retval = VM_FAULT_OOM;
  				goto out_unlock;
  			} else if (unlikely(!page)) {
  				break;
  			}
  			pfn = page_to_pfn(page);
  		}
  
  		ret = vm_insert_mixed(vma, address, pfn);
  		/*
  		 * Somebody beat us to this PTE or prefaulting to
  		 * an already populated PTE, or prefaulting error.
  		 */
  
  		if (unlikely((ret == -EBUSY) || (ret != 0 && i > 0)))
  			break;
  		else if (unlikely(ret != 0)) {
  			retval =
  			    (ret == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
  			goto out_unlock;
  
  		}
  
  		address += PAGE_SIZE;
  		if (unlikely(++page_offset >= page_last))
  			break;
  	}
  
  out_unlock:
  	ttm_bo_unreserve(bo);
  	return retval;
  }
  
  static void ttm_bo_vm_open(struct vm_area_struct *vma)
  {
  	struct ttm_buffer_object *bo =
  	    (struct ttm_buffer_object *)vma->vm_private_data;
  
  	(void)ttm_bo_reference(bo);
  }
  
  static void ttm_bo_vm_close(struct vm_area_struct *vma)
  {
  	struct ttm_buffer_object *bo =
  	    (struct ttm_buffer_object *)vma->vm_private_data;
  
  	ttm_bo_unref(&bo);
  	vma->vm_private_data = NULL;
  }
  
  static const struct vm_operations_struct ttm_bo_vm_ops = {
  	.fault = ttm_bo_vm_fault,
  	.open = ttm_bo_vm_open,
  	.close = ttm_bo_vm_close
  };
  
  int ttm_bo_mmap(struct file *filp, struct vm_area_struct *vma,
  		struct ttm_bo_device *bdev)
  {
  	struct ttm_bo_driver *driver;
  	struct ttm_buffer_object *bo;
  	int ret;
  
  	read_lock(&bdev->vm_lock);
  	bo = ttm_bo_vm_lookup_rb(bdev, vma->vm_pgoff,
  				 (vma->vm_end - vma->vm_start) >> PAGE_SHIFT);
  	if (likely(bo != NULL))
  		ttm_bo_reference(bo);
  	read_unlock(&bdev->vm_lock);
  
  	if (unlikely(bo == NULL)) {
  		printk(KERN_ERR TTM_PFX
  		       "Could not find buffer object to map.\n");
  		return -EINVAL;
  	}
  
  	driver = bo->bdev->driver;
  	if (unlikely(!driver->verify_access)) {
  		ret = -EPERM;
  		goto out_unref;
  	}
  	ret = driver->verify_access(bo, filp);
  	if (unlikely(ret != 0))
  		goto out_unref;
  
  	vma->vm_ops = &ttm_bo_vm_ops;
  
  	/*
  	 * Note: We're transferring the bo reference to
  	 * vma->vm_private_data here.
  	 */
  
  	vma->vm_private_data = bo;
  	vma->vm_flags |= VM_RESERVED | VM_IO | VM_MIXEDMAP | VM_DONTEXPAND;
  	return 0;
  out_unref:
  	ttm_bo_unref(&bo);
  	return ret;
  }
  EXPORT_SYMBOL(ttm_bo_mmap);
  
  int ttm_fbdev_mmap(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
  {
  	if (vma->vm_pgoff != 0)
  		return -EACCES;
  
  	vma->vm_ops = &ttm_bo_vm_ops;
  	vma->vm_private_data = ttm_bo_reference(bo);
  	vma->vm_flags |= VM_RESERVED | VM_IO | VM_MIXEDMAP | VM_DONTEXPAND;
  	return 0;
  }
  EXPORT_SYMBOL(ttm_fbdev_mmap);
  
  
  ssize_t ttm_bo_io(struct ttm_bo_device *bdev, struct file *filp,
  		  const char __user *wbuf, char __user *rbuf, size_t count,
  		  loff_t *f_pos, bool write)
  {
  	struct ttm_buffer_object *bo;
  	struct ttm_bo_driver *driver;
  	struct ttm_bo_kmap_obj map;
  	unsigned long dev_offset = (*f_pos >> PAGE_SHIFT);
  	unsigned long kmap_offset;
  	unsigned long kmap_end;
  	unsigned long kmap_num;
  	size_t io_size;
  	unsigned int page_offset;
  	char *virtual;
  	int ret;
  	bool no_wait = false;
  	bool dummy;
  
  	read_lock(&bdev->vm_lock);
  	bo = ttm_bo_vm_lookup_rb(bdev, dev_offset, 1);
  	if (likely(bo != NULL))
  		ttm_bo_reference(bo);
  	read_unlock(&bdev->vm_lock);
  
  	if (unlikely(bo == NULL))
  		return -EFAULT;
  
  	driver = bo->bdev->driver;
  	if (unlikely(!driver->verify_access)) {
  		ret = -EPERM;
  		goto out_unref;
  	}
  
  	ret = driver->verify_access(bo, filp);
  	if (unlikely(ret != 0))
  		goto out_unref;
  
  	kmap_offset = dev_offset - bo->vm_node->start;
  	if (unlikely(kmap_offset >= bo->num_pages)) {
  		ret = -EFBIG;
  		goto out_unref;
  	}
  
  	page_offset = *f_pos & ~PAGE_MASK;
  	io_size = bo->num_pages - kmap_offset;
  	io_size = (io_size << PAGE_SHIFT) - page_offset;
  	if (count < io_size)
  		io_size = count;
  
  	kmap_end = (*f_pos + count - 1) >> PAGE_SHIFT;
  	kmap_num = kmap_end - kmap_offset + 1;
  
  	ret = ttm_bo_reserve(bo, true, no_wait, false, 0);
  
  	switch (ret) {
  	case 0:
  		break;
  	case -EBUSY:
  		ret = -EAGAIN;
  		goto out_unref;
  	default:
  		goto out_unref;
  	}
  
  	ret = ttm_bo_kmap(bo, kmap_offset, kmap_num, &map);
  	if (unlikely(ret != 0)) {
  		ttm_bo_unreserve(bo);
  		goto out_unref;
  	}
  
  	virtual = ttm_kmap_obj_virtual(&map, &dummy);
  	virtual += page_offset;
  
  	if (write)
  		ret = copy_from_user(virtual, wbuf, io_size);
  	else
  		ret = copy_to_user(rbuf, virtual, io_size);
  
  	ttm_bo_kunmap(&map);
  	ttm_bo_unreserve(bo);
  	ttm_bo_unref(&bo);
  
  	if (unlikely(ret != 0))
  		return -EFBIG;
  
  	*f_pos += io_size;
  
  	return io_size;
  out_unref:
  	ttm_bo_unref(&bo);
  	return ret;
  }
  
  ssize_t ttm_bo_fbdev_io(struct ttm_buffer_object *bo, const char __user *wbuf,
  			char __user *rbuf, size_t count, loff_t *f_pos,
  			bool write)
  {
  	struct ttm_bo_kmap_obj map;
  	unsigned long kmap_offset;
  	unsigned long kmap_end;
  	unsigned long kmap_num;
  	size_t io_size;
  	unsigned int page_offset;
  	char *virtual;
  	int ret;
  	bool no_wait = false;
  	bool dummy;
  
  	kmap_offset = (*f_pos >> PAGE_SHIFT);
  	if (unlikely(kmap_offset >= bo->num_pages))
  		return -EFBIG;
  
  	page_offset = *f_pos & ~PAGE_MASK;
  	io_size = bo->num_pages - kmap_offset;
  	io_size = (io_size << PAGE_SHIFT) - page_offset;
  	if (count < io_size)
  		io_size = count;
  
  	kmap_end = (*f_pos + count - 1) >> PAGE_SHIFT;
  	kmap_num = kmap_end - kmap_offset + 1;
  
  	ret = ttm_bo_reserve(bo, true, no_wait, false, 0);
  
  	switch (ret) {
  	case 0:
  		break;
  	case -EBUSY:
  		return -EAGAIN;
  	default:
  		return ret;
  	}
  
  	ret = ttm_bo_kmap(bo, kmap_offset, kmap_num, &map);
  	if (unlikely(ret != 0)) {
  		ttm_bo_unreserve(bo);
  		return ret;
  	}
  
  	virtual = ttm_kmap_obj_virtual(&map, &dummy);
  	virtual += page_offset;
  
  	if (write)
  		ret = copy_from_user(virtual, wbuf, io_size);
  	else
  		ret = copy_to_user(rbuf, virtual, io_size);
  
  	ttm_bo_kunmap(&map);
  	ttm_bo_unreserve(bo);
  	ttm_bo_unref(&bo);
  
  	if (unlikely(ret != 0))
  		return ret;
  
  	*f_pos += io_size;
  
  	return io_size;
  }
  