text: /*
   * SPDX-License-Identifier: MIT
   *
   * Copyright © 2018 Intel Corporation
   */
  
  #include <linux/nospec.h>
  
  #include "i915_drv.h"
  #include "i915_query.h"
  #include <uapi/drm/i915_drm.h>
  
  static int copy_query_item(void *query_hdr, size_t query_sz,
  			   u32 total_length,
  			   struct drm_i915_query_item *query_item)
  {
  	if (query_item->length == 0)
  		return total_length;
  
  	if (query_item->length < total_length)
  		return -EINVAL;
  
  	if (copy_from_user(query_hdr, u64_to_user_ptr(query_item->data_ptr),
  			   query_sz))
  		return -EFAULT;
  
  	if (!access_ok(u64_to_user_ptr(query_item->data_ptr),
  		       total_length))
  		return -EFAULT;
  
  	return 0;
  }
  
  static int query_topology_info(struct drm_i915_private *dev_priv,
  			       struct drm_i915_query_item *query_item)
  {
  	const struct sseu_dev_info *sseu = &RUNTIME_INFO(dev_priv)->sseu;
  	struct drm_i915_query_topology_info topo;
  	u32 slice_length, subslice_length, eu_length, total_length;
  	int ret;
  
  	if (query_item->flags != 0)
  		return -EINVAL;
  
  	if (sseu->max_slices == 0)
  		return -ENODEV;
  
  	BUILD_BUG_ON(sizeof(u8) != sizeof(sseu->slice_mask));
  
  	slice_length = sizeof(sseu->slice_mask);
  	subslice_length = sseu->max_slices *
  		DIV_ROUND_UP(sseu->max_subslices, BITS_PER_BYTE);
  	eu_length = sseu->max_slices * sseu->max_subslices *
  		DIV_ROUND_UP(sseu->max_eus_per_subslice, BITS_PER_BYTE);
  
  	total_length = sizeof(topo) + slice_length + subslice_length + eu_length;
  
  	ret = copy_query_item(&topo, sizeof(topo), total_length,
  			      query_item);
  	if (ret != 0)
  		return ret;
  
  	if (topo.flags != 0)
  		return -EINVAL;
  
  	memset(&topo, 0, sizeof(topo));
  	topo.max_slices = sseu->max_slices;
  	topo.max_subslices = sseu->max_subslices;
  	topo.max_eus_per_subslice = sseu->max_eus_per_subslice;
  
  	topo.subslice_offset = slice_length;
  	topo.subslice_stride = DIV_ROUND_UP(sseu->max_subslices, BITS_PER_BYTE);
  	topo.eu_offset = slice_length + subslice_length;
  	topo.eu_stride =
  		DIV_ROUND_UP(sseu->max_eus_per_subslice, BITS_PER_BYTE);
  
  	if (__copy_to_user(u64_to_user_ptr(query_item->data_ptr),
  			   &topo, sizeof(topo)))
  		return -EFAULT;
  
  	if (__copy_to_user(u64_to_user_ptr(query_item->data_ptr + sizeof(topo)),
  			   &sseu->slice_mask, slice_length))
  		return -EFAULT;
  
  	if (__copy_to_user(u64_to_user_ptr(query_item->data_ptr +
  					   sizeof(topo) + slice_length),
  			   sseu->subslice_mask, subslice_length))
  		return -EFAULT;
  
  	if (__copy_to_user(u64_to_user_ptr(query_item->data_ptr +
  					   sizeof(topo) +
  					   slice_length + subslice_length),
  			   sseu->eu_mask, eu_length))
  		return -EFAULT;
  
  	return total_length;
  }
  
  static int (* const i915_query_funcs[])(struct drm_i915_private *dev_priv,
  					struct drm_i915_query_item *query_item) = {
  	query_topology_info,
  };
  
  int i915_query_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
  {
  	struct drm_i915_private *dev_priv = to_i915(dev);
  	struct drm_i915_query *args = data;
  	struct drm_i915_query_item __user *user_item_ptr =
  		u64_to_user_ptr(args->items_ptr);
  	u32 i;
  
  	if (args->flags != 0)
  		return -EINVAL;
  
  	for (i = 0; i < args->num_items; i++, user_item_ptr++) {
  		struct drm_i915_query_item item;
  		unsigned long func_idx;
  		int ret;
  
  		if (copy_from_user(&item, user_item_ptr, sizeof(item)))
  			return -EFAULT;
  
  		if (item.query_id == 0)
  			return -EINVAL;
  
  		if (overflows_type(item.query_id - 1, unsigned long))
  			return -EINVAL;
  
  		func_idx = item.query_id - 1;
  
  		ret = -EINVAL;
  		if (func_idx < ARRAY_SIZE(i915_query_funcs)) {
  			func_idx = array_index_nospec(func_idx,
  						      ARRAY_SIZE(i915_query_funcs));
  			ret = i915_query_funcs[func_idx](dev_priv, &item);
  		}
  
  		/* Only write the length back to userspace if they differ. */
  		if (ret != item.length && put_user(ret, &user_item_ptr->length))
  			return -EFAULT;
  	}
  
  	return 0;
  }
  