drm/i915: Split i915_gem_execbuffer into its own file.

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / gpu / drm / i915 / i915_gem.c

/*
 * Copyright © 2008 Intel Corporation
 *
 * 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, sublicense,
 * 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 NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS 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:
 *    Eric Anholt <eric@anholt.net>
 *
 */

#include "drmP.h"
#include "drm.h"
#include "i915_drm.h"
#include "i915_drv.h"
#include "i915_trace.h"
#include "intel_drv.h"
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/pci.h>

static int i915_gem_object_flush_gpu_write_domain(struct drm_i915_gem_object *obj,
                                                  struct intel_ring_buffer *pipelined);
static void i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj);
static void i915_gem_object_flush_cpu_write_domain(struct drm_i915_gem_object *obj);
static int i915_gem_object_set_to_cpu_domain(struct drm_i915_gem_object *obj,
                                             bool write);
static int i915_gem_object_set_cpu_read_domain_range(struct drm_i915_gem_object *obj,
                                                     uint64_t offset,
                                                     uint64_t size);
static void i915_gem_object_set_to_full_cpu_read_domain(struct drm_i915_gem_object *obj);
static int i915_gem_object_bind_to_gtt(struct drm_i915_gem_object *obj,
                                       unsigned alignment,
                                       bool map_and_fenceable);
static void i915_gem_clear_fence_reg(struct drm_i915_gem_object *obj);
static int i915_gem_phys_pwrite(struct drm_device *dev,
                                struct drm_i915_gem_object *obj,
                                struct drm_i915_gem_pwrite *args,
                                struct drm_file *file);
static void i915_gem_free_object_tail(struct drm_i915_gem_object *obj);

static int i915_gem_inactive_shrink(struct shrinker *shrinker,
                                    int nr_to_scan,
                                    gfp_t gfp_mask);


/* some bookkeeping */
static void i915_gem_info_add_obj(struct drm_i915_private *dev_priv,
                                  size_t size)
{
        dev_priv->mm.object_count++;
        dev_priv->mm.object_memory += size;
}

static void i915_gem_info_remove_obj(struct drm_i915_private *dev_priv,
                                     size_t size)
{
        dev_priv->mm.object_count--;
        dev_priv->mm.object_memory -= size;
}

int
i915_gem_check_is_wedged(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct completion *x = &dev_priv->error_completion;
        unsigned long flags;
        int ret;

        if (!atomic_read(&dev_priv->mm.wedged))
                return 0;

        ret = wait_for_completion_interruptible(x);
        if (ret)
                return ret;

        /* Success, we reset the GPU! */
        if (!atomic_read(&dev_priv->mm.wedged))
                return 0;

        /* GPU is hung, bump the completion count to account for
         * the token we just consumed so that we never hit zero and
         * end up waiting upon a subsequent completion event that
         * will never happen.
         */
        spin_lock_irqsave(&x->wait.lock, flags);
        x->done++;
        spin_unlock_irqrestore(&x->wait.lock, flags);
        return -EIO;
}

int i915_mutex_lock_interruptible(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        int ret;

        ret = i915_gem_check_is_wedged(dev);
        if (ret)
                return ret;

        ret = mutex_lock_interruptible(&dev->struct_mutex);
        if (ret)
                return ret;

        if (atomic_read(&dev_priv->mm.wedged)) {
                mutex_unlock(&dev->struct_mutex);
                return -EAGAIN;
        }

        WARN_ON(i915_verify_lists(dev));
        return 0;
}

static inline bool
i915_gem_object_is_inactive(struct drm_i915_gem_object *obj)
{
        return obj->gtt_space && !obj->active && obj->pin_count == 0;
}

void i915_gem_do_init(struct drm_device *dev,
                      unsigned long start,
                      unsigned long mappable_end,
                      unsigned long end)
{
        drm_i915_private_t *dev_priv = dev->dev_private;

        drm_mm_init(&dev_priv->mm.gtt_space, start,
                    end - start);

        dev_priv->mm.gtt_total = end - start;
        dev_priv->mm.mappable_gtt_total = min(end, mappable_end) - start;
        dev_priv->mm.gtt_mappable_end = mappable_end;
}

int
i915_gem_init_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file)
{
        struct drm_i915_gem_init *args = data;

        if (args->gtt_start >= args->gtt_end ||
            (args->gtt_end | args->gtt_start) & (PAGE_SIZE - 1))
                return -EINVAL;

        mutex_lock(&dev->struct_mutex);
        i915_gem_do_init(dev, args->gtt_start, args->gtt_end, args->gtt_end);
        mutex_unlock(&dev->struct_mutex);

        return 0;
}

int
i915_gem_get_aperture_ioctl(struct drm_device *dev, void *data,
                            struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_get_aperture *args = data;
        struct drm_i915_gem_object *obj;
        size_t pinned;

        if (!(dev->driver->driver_features & DRIVER_GEM))
                return -ENODEV;

        pinned = 0;
        mutex_lock(&dev->struct_mutex);
        list_for_each_entry(obj, &dev_priv->mm.pinned_list, mm_list)
                pinned += obj->gtt_space->size;
        mutex_unlock(&dev->struct_mutex);

        args->aper_size = dev_priv->mm.gtt_total;
        args->aper_available_size = args->aper_size -pinned;

        return 0;
}

/**
 * Creates a new mm object and returns a handle to it.
 */
int
i915_gem_create_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file)
{
        struct drm_i915_gem_create *args = data;
        struct drm_i915_gem_object *obj;
        int ret;
        u32 handle;

        args->size = roundup(args->size, PAGE_SIZE);

        /* Allocate the new object */
        obj = i915_gem_alloc_object(dev, args->size);
        if (obj == NULL)
                return -ENOMEM;

        ret = drm_gem_handle_create(file, &obj->base, &handle);
        if (ret) {
                drm_gem_object_release(&obj->base);
                i915_gem_info_remove_obj(dev->dev_private, obj->base.size);
                kfree(obj);
                return ret;
        }

        /* drop reference from allocate - handle holds it now */
        drm_gem_object_unreference(&obj->base);
        trace_i915_gem_object_create(obj);

        args->handle = handle;
        return 0;
}

static int i915_gem_object_needs_bit17_swizzle(struct drm_i915_gem_object *obj)
{
        drm_i915_private_t *dev_priv = obj->base.dev->dev_private;

        return dev_priv->mm.bit_6_swizzle_x == I915_BIT_6_SWIZZLE_9_10_17 &&
                obj->tiling_mode != I915_TILING_NONE;
}

static inline void
slow_shmem_copy(struct page *dst_page,
                int dst_offset,
                struct page *src_page,
                int src_offset,
                int length)
{
        char *dst_vaddr, *src_vaddr;

        dst_vaddr = kmap(dst_page);
        src_vaddr = kmap(src_page);

        memcpy(dst_vaddr + dst_offset, src_vaddr + src_offset, length);

        kunmap(src_page);
        kunmap(dst_page);
}

static inline void
slow_shmem_bit17_copy(struct page *gpu_page,
                      int gpu_offset,
                      struct page *cpu_page,
                      int cpu_offset,
                      int length,
                      int is_read)
{
        char *gpu_vaddr, *cpu_vaddr;

        /* Use the unswizzled path if this page isn't affected. */
        if ((page_to_phys(gpu_page) & (1 << 17)) == 0) {
                if (is_read)
                        return slow_shmem_copy(cpu_page, cpu_offset,
                                               gpu_page, gpu_offset, length);
                else
                        return slow_shmem_copy(gpu_page, gpu_offset,
                                               cpu_page, cpu_offset, length);
        }

        gpu_vaddr = kmap(gpu_page);
        cpu_vaddr = kmap(cpu_page);

        /* Copy the data, XORing A6 with A17 (1). The user already knows he's
         * XORing with the other bits (A9 for Y, A9 and A10 for X)
         */
        while (length > 0) {
                int cacheline_end = ALIGN(gpu_offset + 1, 64);
                int this_length = min(cacheline_end - gpu_offset, length);
                int swizzled_gpu_offset = gpu_offset ^ 64;

                if (is_read) {
                        memcpy(cpu_vaddr + cpu_offset,
                               gpu_vaddr + swizzled_gpu_offset,
                               this_length);
                } else {
                        memcpy(gpu_vaddr + swizzled_gpu_offset,
                               cpu_vaddr + cpu_offset,
                               this_length);
                }
                cpu_offset += this_length;
                gpu_offset += this_length;
                length -= this_length;
        }

        kunmap(cpu_page);
        kunmap(gpu_page);
}

/**
 * This is the fast shmem pread path, which attempts to copy_from_user directly
 * from the backing pages of the object to the user's address space.  On a
 * fault, it fails so we can fall back to i915_gem_shmem_pwrite_slow().
 */
static int
i915_gem_shmem_pread_fast(struct drm_device *dev,
                          struct drm_i915_gem_object *obj,
                          struct drm_i915_gem_pread *args,
                          struct drm_file *file)
{
        struct address_space *mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
        ssize_t remain;
        loff_t offset;
        char __user *user_data;
        int page_offset, page_length;

        user_data = (char __user *) (uintptr_t) args->data_ptr;
        remain = args->size;

        offset = args->offset;

        while (remain > 0) {
                struct page *page;
                char *vaddr;
                int ret;

                /* Operation in this page
                 *
                 * page_offset = offset within page
                 * page_length = bytes to copy for this page
                 */
                page_offset = offset & (PAGE_SIZE-1);
                page_length = remain;
                if ((page_offset + remain) > PAGE_SIZE)
                        page_length = PAGE_SIZE - page_offset;

                page = read_cache_page_gfp(mapping, offset >> PAGE_SHIFT,
                                           GFP_HIGHUSER | __GFP_RECLAIMABLE);
                if (IS_ERR(page))
                        return PTR_ERR(page);

                vaddr = kmap_atomic(page);
                ret = __copy_to_user_inatomic(user_data,
                                              vaddr + page_offset,
                                              page_length);
                kunmap_atomic(vaddr);

                mark_page_accessed(page);
                page_cache_release(page);
                if (ret)
                        return -EFAULT;

                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

        return 0;
}

/**
 * This is the fallback shmem pread path, which allocates temporary storage
 * in kernel space to copy_to_user into outside of the struct_mutex, so we
 * can copy out of the object's backing pages while holding the struct mutex
 * and not take page faults.
 */
static int
i915_gem_shmem_pread_slow(struct drm_device *dev,
                          struct drm_i915_gem_object *obj,
                          struct drm_i915_gem_pread *args,
                          struct drm_file *file)
{
        struct address_space *mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
        struct mm_struct *mm = current->mm;
        struct page **user_pages;
        ssize_t remain;
        loff_t offset, pinned_pages, i;
        loff_t first_data_page, last_data_page, num_pages;
        int shmem_page_offset;
        int data_page_index, data_page_offset;
        int page_length;
        int ret;
        uint64_t data_ptr = args->data_ptr;
        int do_bit17_swizzling;

        remain = args->size;

        /* Pin the user pages containing the data.  We can't fault while
         * holding the struct mutex, yet we want to hold it while
         * dereferencing the user data.
         */
        first_data_page = data_ptr / PAGE_SIZE;
        last_data_page = (data_ptr + args->size - 1) / PAGE_SIZE;
        num_pages = last_data_page - first_data_page + 1;

        user_pages = drm_malloc_ab(num_pages, sizeof(struct page *));
        if (user_pages == NULL)
                return -ENOMEM;

        mutex_unlock(&dev->struct_mutex);
        down_read(&mm->mmap_sem);
        pinned_pages = get_user_pages(current, mm, (uintptr_t)args->data_ptr,
                                      num_pages, 1, 0, user_pages, NULL);
        up_read(&mm->mmap_sem);
        mutex_lock(&dev->struct_mutex);
        if (pinned_pages < num_pages) {
                ret = -EFAULT;
                goto out;
        }

        ret = i915_gem_object_set_cpu_read_domain_range(obj,
                                                        args->offset,
                                                        args->size);
        if (ret)
                goto out;

        do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);

        offset = args->offset;

        while (remain > 0) {
                struct page *page;

                /* Operation in this page
                 *
                 * shmem_page_offset = offset within page in shmem file
                 * data_page_index = page number in get_user_pages return
                 * data_page_offset = offset with data_page_index page.
                 * page_length = bytes to copy for this page
                 */
                shmem_page_offset = offset & ~PAGE_MASK;
                data_page_index = data_ptr / PAGE_SIZE - first_data_page;
                data_page_offset = data_ptr & ~PAGE_MASK;

                page_length = remain;
                if ((shmem_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - shmem_page_offset;
                if ((data_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - data_page_offset;

                page = read_cache_page_gfp(mapping, offset >> PAGE_SHIFT,
                                           GFP_HIGHUSER | __GFP_RECLAIMABLE);
                if (IS_ERR(page))
                        return PTR_ERR(page);

                if (do_bit17_swizzling) {
                        slow_shmem_bit17_copy(page,
                                              shmem_page_offset,
                                              user_pages[data_page_index],
                                              data_page_offset,
                                              page_length,
                                              1);
                } else {
                        slow_shmem_copy(user_pages[data_page_index],
                                        data_page_offset,
                                        page,
                                        shmem_page_offset,
                                        page_length);
                }

                mark_page_accessed(page);
                page_cache_release(page);

                remain -= page_length;
                data_ptr += page_length;
                offset += page_length;
        }

out:
        for (i = 0; i < pinned_pages; i++) {
                SetPageDirty(user_pages[i]);
                mark_page_accessed(user_pages[i]);
                page_cache_release(user_pages[i]);
        }
        drm_free_large(user_pages);

        return ret;
}

/**
 * Reads data from the object referenced by handle.
 *
 * On error, the contents of *data are undefined.
 */
int
i915_gem_pread_ioctl(struct drm_device *dev, void *data,
                     struct drm_file *file)
{
        struct drm_i915_gem_pread *args = data;
        struct drm_i915_gem_object *obj;
        int ret = 0;

        if (args->size == 0)
                return 0;

        if (!access_ok(VERIFY_WRITE,
                       (char __user *)(uintptr_t)args->data_ptr,
                       args->size))
                return -EFAULT;

        ret = fault_in_pages_writeable((char __user *)(uintptr_t)args->data_ptr,
                                       args->size);
        if (ret)
                return -EFAULT;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (obj == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Bounds check source.  */
        if (args->offset > obj->base.size ||
            args->size > obj->base.size - args->offset) {
                ret = -EINVAL;
                goto out;
        }

        ret = i915_gem_object_set_cpu_read_domain_range(obj,
                                                        args->offset,
                                                        args->size);
        if (ret)
                goto out;

        ret = -EFAULT;
        if (!i915_gem_object_needs_bit17_swizzle(obj))
                ret = i915_gem_shmem_pread_fast(dev, obj, args, file);
        if (ret == -EFAULT)
                ret = i915_gem_shmem_pread_slow(dev, obj, args, file);

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/* This is the fast write path which cannot handle
 * page faults in the source data
 */

static inline int
fast_user_write(struct io_mapping *mapping,
                loff_t page_base, int page_offset,
                char __user *user_data,
                int length)
{
        char *vaddr_atomic;
        unsigned long unwritten;

        vaddr_atomic = io_mapping_map_atomic_wc(mapping, page_base);
        unwritten = __copy_from_user_inatomic_nocache(vaddr_atomic + page_offset,
                                                      user_data, length);
        io_mapping_unmap_atomic(vaddr_atomic);
        return unwritten;
}

/* Here's the write path which can sleep for
 * page faults
 */

static inline void
slow_kernel_write(struct io_mapping *mapping,
                  loff_t gtt_base, int gtt_offset,
                  struct page *user_page, int user_offset,
                  int length)
{
        char __iomem *dst_vaddr;
        char *src_vaddr;

        dst_vaddr = io_mapping_map_wc(mapping, gtt_base);
        src_vaddr = kmap(user_page);

        memcpy_toio(dst_vaddr + gtt_offset,
                    src_vaddr + user_offset,
                    length);

        kunmap(user_page);
        io_mapping_unmap(dst_vaddr);
}

/**
 * This is the fast pwrite path, where we copy the data directly from the
 * user into the GTT, uncached.
 */
static int
i915_gem_gtt_pwrite_fast(struct drm_device *dev,
                         struct drm_i915_gem_object *obj,
                         struct drm_i915_gem_pwrite *args,
                         struct drm_file *file)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        ssize_t remain;
        loff_t offset, page_base;
        char __user *user_data;
        int page_offset, page_length;

        user_data = (char __user *) (uintptr_t) args->data_ptr;
        remain = args->size;

        offset = obj->gtt_offset + args->offset;

        while (remain > 0) {
                /* Operation in this page
                 *
                 * page_base = page offset within aperture
                 * page_offset = offset within page
                 * page_length = bytes to copy for this page
                 */
                page_base = (offset & ~(PAGE_SIZE-1));
                page_offset = offset & (PAGE_SIZE-1);
                page_length = remain;
                if ((page_offset + remain) > PAGE_SIZE)
                        page_length = PAGE_SIZE - page_offset;

                /* If we get a fault while copying data, then (presumably) our
                 * source page isn't available.  Return the error and we'll
                 * retry in the slow path.
                 */
                if (fast_user_write(dev_priv->mm.gtt_mapping, page_base,
                                    page_offset, user_data, page_length))

                        return -EFAULT;

                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

        return 0;
}

/**
 * This is the fallback GTT pwrite path, which uses get_user_pages to pin
 * the memory and maps it using kmap_atomic for copying.
 *
 * This code resulted in x11perf -rgb10text consuming about 10% more CPU
 * than using i915_gem_gtt_pwrite_fast on a G45 (32-bit).
 */
static int
i915_gem_gtt_pwrite_slow(struct drm_device *dev,
                         struct drm_i915_gem_object *obj,
                         struct drm_i915_gem_pwrite *args,
                         struct drm_file *file)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        ssize_t remain;
        loff_t gtt_page_base, offset;
        loff_t first_data_page, last_data_page, num_pages;
        loff_t pinned_pages, i;
        struct page **user_pages;
        struct mm_struct *mm = current->mm;
        int gtt_page_offset, data_page_offset, data_page_index, page_length;
        int ret;
        uint64_t data_ptr = args->data_ptr;

        remain = args->size;

        /* Pin the user pages containing the data.  We can't fault while
         * holding the struct mutex, and all of the pwrite implementations
         * want to hold it while dereferencing the user data.
         */
        first_data_page = data_ptr / PAGE_SIZE;
        last_data_page = (data_ptr + args->size - 1) / PAGE_SIZE;
        num_pages = last_data_page - first_data_page + 1;

        user_pages = drm_malloc_ab(num_pages, sizeof(struct page *));
        if (user_pages == NULL)
                return -ENOMEM;

        mutex_unlock(&dev->struct_mutex);
        down_read(&mm->mmap_sem);
        pinned_pages = get_user_pages(current, mm, (uintptr_t)args->data_ptr,
                                      num_pages, 0, 0, user_pages, NULL);
        up_read(&mm->mmap_sem);
        mutex_lock(&dev->struct_mutex);
        if (pinned_pages < num_pages) {
                ret = -EFAULT;
                goto out_unpin_pages;
        }

        ret = i915_gem_object_set_to_gtt_domain(obj, 1);
        if (ret)
                goto out_unpin_pages;

        offset = obj->gtt_offset + args->offset;

        while (remain > 0) {
                /* Operation in this page
                 *
                 * gtt_page_base = page offset within aperture
                 * gtt_page_offset = offset within page in aperture
                 * data_page_index = page number in get_user_pages return
                 * data_page_offset = offset with data_page_index page.
                 * page_length = bytes to copy for this page
                 */
                gtt_page_base = offset & PAGE_MASK;
                gtt_page_offset = offset & ~PAGE_MASK;
                data_page_index = data_ptr / PAGE_SIZE - first_data_page;
                data_page_offset = data_ptr & ~PAGE_MASK;

                page_length = remain;
                if ((gtt_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - gtt_page_offset;
                if ((data_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - data_page_offset;

                slow_kernel_write(dev_priv->mm.gtt_mapping,
                                  gtt_page_base, gtt_page_offset,
                                  user_pages[data_page_index],
                                  data_page_offset,
                                  page_length);

                remain -= page_length;
                offset += page_length;
                data_ptr += page_length;
        }

out_unpin_pages:
        for (i = 0; i < pinned_pages; i++)
                page_cache_release(user_pages[i]);
        drm_free_large(user_pages);

        return ret;
}

/**
 * This is the fast shmem pwrite path, which attempts to directly
 * copy_from_user into the kmapped pages backing the object.
 */
static int
i915_gem_shmem_pwrite_fast(struct drm_device *dev,
                           struct drm_i915_gem_object *obj,
                           struct drm_i915_gem_pwrite *args,
                           struct drm_file *file)
{
        struct address_space *mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
        ssize_t remain;
        loff_t offset;
        char __user *user_data;
        int page_offset, page_length;

        user_data = (char __user *) (uintptr_t) args->data_ptr;
        remain = args->size;

        offset = args->offset;
        obj->dirty = 1;

        while (remain > 0) {
                struct page *page;
                char *vaddr;
                int ret;

                /* Operation in this page
                 *
                 * page_offset = offset within page
                 * page_length = bytes to copy for this page
                 */
                page_offset = offset & (PAGE_SIZE-1);
                page_length = remain;
                if ((page_offset + remain) > PAGE_SIZE)
                        page_length = PAGE_SIZE - page_offset;

                page = read_cache_page_gfp(mapping, offset >> PAGE_SHIFT,
                                           GFP_HIGHUSER | __GFP_RECLAIMABLE);
                if (IS_ERR(page))
                        return PTR_ERR(page);

                vaddr = kmap_atomic(page, KM_USER0);
                ret = __copy_from_user_inatomic(vaddr + page_offset,
                                                user_data,
                                                page_length);
                kunmap_atomic(vaddr, KM_USER0);

                set_page_dirty(page);
                mark_page_accessed(page);
                page_cache_release(page);

                /* If we get a fault while copying data, then (presumably) our
                 * source page isn't available.  Return the error and we'll
                 * retry in the slow path.
                 */
                if (ret)
                        return -EFAULT;

                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

        return 0;
}

/**
 * This is the fallback shmem pwrite path, which uses get_user_pages to pin
 * the memory and maps it using kmap_atomic for copying.
 *
 * This avoids taking mmap_sem for faulting on the user's address while the
 * struct_mutex is held.
 */
static int
i915_gem_shmem_pwrite_slow(struct drm_device *dev,
                           struct drm_i915_gem_object *obj,
                           struct drm_i915_gem_pwrite *args,
                           struct drm_file *file)
{
        struct address_space *mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
        struct mm_struct *mm = current->mm;
        struct page **user_pages;
        ssize_t remain;
        loff_t offset, pinned_pages, i;
        loff_t first_data_page, last_data_page, num_pages;
        int shmem_page_offset;
        int data_page_index,  data_page_offset;
        int page_length;
        int ret;
        uint64_t data_ptr = args->data_ptr;
        int do_bit17_swizzling;

        remain = args->size;

        /* Pin the user pages containing the data.  We can't fault while
         * holding the struct mutex, and all of the pwrite implementations
         * want to hold it while dereferencing the user data.
         */
        first_data_page = data_ptr / PAGE_SIZE;
        last_data_page = (data_ptr + args->size - 1) / PAGE_SIZE;
        num_pages = last_data_page - first_data_page + 1;

        user_pages = drm_malloc_ab(num_pages, sizeof(struct page *));
        if (user_pages == NULL)
                return -ENOMEM;

        mutex_unlock(&dev->struct_mutex);
        down_read(&mm->mmap_sem);
        pinned_pages = get_user_pages(current, mm, (uintptr_t)args->data_ptr,
                                      num_pages, 0, 0, user_pages, NULL);
        up_read(&mm->mmap_sem);
        mutex_lock(&dev->struct_mutex);
        if (pinned_pages < num_pages) {
                ret = -EFAULT;
                goto out;
        }

        ret = i915_gem_object_set_to_cpu_domain(obj, 1);
        if (ret)
                goto out;

        do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);

        offset = args->offset;
        obj->dirty = 1;

        while (remain > 0) {
                struct page *page;

                /* Operation in this page
                 *
                 * shmem_page_offset = offset within page in shmem file
                 * data_page_index = page number in get_user_pages return
                 * data_page_offset = offset with data_page_index page.
                 * page_length = bytes to copy for this page
                 */
                shmem_page_offset = offset & ~PAGE_MASK;
                data_page_index = data_ptr / PAGE_SIZE - first_data_page;
                data_page_offset = data_ptr & ~PAGE_MASK;

                page_length = remain;
                if ((shmem_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - shmem_page_offset;
                if ((data_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - data_page_offset;

                page = read_cache_page_gfp(mapping, offset >> PAGE_SHIFT,
                                           GFP_HIGHUSER | __GFP_RECLAIMABLE);
                if (IS_ERR(page)) {
                        ret = PTR_ERR(page);
                        goto out;
                }

                if (do_bit17_swizzling) {
                        slow_shmem_bit17_copy(page,
                                              shmem_page_offset,
                                              user_pages[data_page_index],
                                              data_page_offset,
                                              page_length,
                                              0);
                } else {
                        slow_shmem_copy(page,
                                        shmem_page_offset,
                                        user_pages[data_page_index],
                                        data_page_offset,
                                        page_length);
                }

                set_page_dirty(page);
                mark_page_accessed(page);
                page_cache_release(page);

                remain -= page_length;
                data_ptr += page_length;
                offset += page_length;
        }

out:
        for (i = 0; i < pinned_pages; i++)
                page_cache_release(user_pages[i]);
        drm_free_large(user_pages);

        return ret;
}

/**
 * Writes data to the object referenced by handle.
 *
 * On error, the contents of the buffer that were to be modified are undefined.
 */
int
i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file)
{
        struct drm_i915_gem_pwrite *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        if (args->size == 0)
                return 0;

        if (!access_ok(VERIFY_READ,
                       (char __user *)(uintptr_t)args->data_ptr,
                       args->size))
                return -EFAULT;

        ret = fault_in_pages_readable((char __user *)(uintptr_t)args->data_ptr,
                                      args->size);
        if (ret)
                return -EFAULT;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (obj == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Bounds check destination. */
        if (args->offset > obj->base.size ||
            args->size > obj->base.size - args->offset) {
                ret = -EINVAL;
                goto out;
        }

        /* We can only do the GTT pwrite on untiled buffers, as otherwise
         * it would end up going through the fenced access, and we'll get
         * different detiling behavior between reading and writing.
         * pread/pwrite currently are reading and writing from the CPU
         * perspective, requiring manual detiling by the client.
         */
        if (obj->phys_obj)
                ret = i915_gem_phys_pwrite(dev, obj, args, file);
        else if (obj->tiling_mode == I915_TILING_NONE &&
                 obj->gtt_space &&
                 obj->base.write_domain != I915_GEM_DOMAIN_CPU) {
                ret = i915_gem_object_pin(obj, 0, true);
                if (ret)
                        goto out;

                ret = i915_gem_object_set_to_gtt_domain(obj, 1);
                if (ret)
                        goto out_unpin;

                ret = i915_gem_gtt_pwrite_fast(dev, obj, args, file);
                if (ret == -EFAULT)
                        ret = i915_gem_gtt_pwrite_slow(dev, obj, args, file);

out_unpin:
                i915_gem_object_unpin(obj);
        } else {
                ret = i915_gem_object_set_to_cpu_domain(obj, 1);
                if (ret)
                        goto out;

                ret = -EFAULT;
                if (!i915_gem_object_needs_bit17_swizzle(obj))
                        ret = i915_gem_shmem_pwrite_fast(dev, obj, args, file);
                if (ret == -EFAULT)
                        ret = i915_gem_shmem_pwrite_slow(dev, obj, args, file);
        }

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/**
 * Called when user space prepares to use an object with the CPU, either
 * through the mmap ioctl's mapping or a GTT mapping.
 */
int
i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
                          struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_set_domain *args = data;
        struct drm_i915_gem_object *obj;
        uint32_t read_domains = args->read_domains;
        uint32_t write_domain = args->write_domain;
        int ret;

        if (!(dev->driver->driver_features & DRIVER_GEM))
                return -ENODEV;

        /* Only handle setting domains to types used by the CPU. */
        if (write_domain & I915_GEM_GPU_DOMAINS)
                return -EINVAL;

        if (read_domains & I915_GEM_GPU_DOMAINS)
                return -EINVAL;

        /* Having something in the write domain implies it's in the read
         * domain, and only that read domain.  Enforce that in the request.
         */
        if (write_domain != 0 && read_domains != write_domain)
                return -EINVAL;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (obj == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        intel_mark_busy(dev, obj);

        if (read_domains & I915_GEM_DOMAIN_GTT) {
                ret = i915_gem_object_set_to_gtt_domain(obj, write_domain != 0);

                /* Update the LRU on the fence for the CPU access that's
                 * about to occur.
                 */
                if (obj->fence_reg != I915_FENCE_REG_NONE) {
                        struct drm_i915_fence_reg *reg =
                                &dev_priv->fence_regs[obj->fence_reg];
                        list_move_tail(&reg->lru_list,
                                       &dev_priv->mm.fence_list);
                }

                /* Silently promote "you're not bound, there was nothing to do"
                 * to success, since the client was just asking us to
                 * make sure everything was done.
                 */
                if (ret == -EINVAL)
                        ret = 0;
        } else {
                ret = i915_gem_object_set_to_cpu_domain(obj, write_domain != 0);
        }

        /* Maintain LRU order of "inactive" objects */
        if (ret == 0 && i915_gem_object_is_inactive(obj))
                list_move_tail(&obj->mm_list, &dev_priv->mm.inactive_list);

        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/**
 * Called when user space has done writes to this buffer
 */
int
i915_gem_sw_finish_ioctl(struct drm_device *dev, void *data,
                         struct drm_file *file)
{
        struct drm_i915_gem_sw_finish *args = data;
        struct drm_i915_gem_object *obj;
        int ret = 0;

        if (!(dev->driver->driver_features & DRIVER_GEM))
                return -ENODEV;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (obj == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Pinned buffers may be scanout, so flush the cache */
        if (obj->pin_count)
                i915_gem_object_flush_cpu_write_domain(obj);

        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/**
 * Maps the contents of an object, returning the address it is mapped
 * into.
 *
 * While the mapping holds a reference on the contents of the object, it doesn't
 * imply a ref on the object itself.
 */
int
i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_mmap *args = data;
        struct drm_gem_object *obj;
        loff_t offset;
        unsigned long addr;

        if (!(dev->driver->driver_features & DRIVER_GEM))
                return -ENODEV;

        obj = drm_gem_object_lookup(dev, file, args->handle);
        if (obj == NULL)
                return -ENOENT;

        if (obj->size > dev_priv->mm.gtt_mappable_end) {
                drm_gem_object_unreference_unlocked(obj);
                return -E2BIG;
        }

        offset = args->offset;

        down_write(&current->mm->mmap_sem);
        addr = do_mmap(obj->filp, 0, args->size,
                       PROT_READ | PROT_WRITE, MAP_SHARED,
                       args->offset);
        up_write(&current->mm->mmap_sem);
        drm_gem_object_unreference_unlocked(obj);
        if (IS_ERR((void *)addr))
                return addr;

        args->addr_ptr = (uint64_t) addr;

        return 0;
}

/**
 * i915_gem_fault - fault a page into the GTT
 * vma: VMA in question
 * vmf: fault info
 *
 * The fault handler is set up by drm_gem_mmap() when a object is GTT mapped
 * from userspace.  The fault handler takes care of binding the object to
 * the GTT (if needed), allocating and programming a fence register (again,
 * only if needed based on whether the old reg is still valid or the object
 * is tiled) and inserting a new PTE into the faulting process.
 *
 * Note that the faulting process may involve evicting existing objects
 * from the GTT and/or fence registers to make room.  So performance may
 * suffer if the GTT working set is large or there are few fence registers
 * left.
 */
int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct drm_i915_gem_object *obj = to_intel_bo(vma->vm_private_data);
        struct drm_device *dev = obj->base.dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        pgoff_t page_offset;
        unsigned long pfn;
        int ret = 0;
        bool write = !!(vmf->flags & FAULT_FLAG_WRITE);

        /* We don't use vmf->pgoff since that has the fake offset */
        page_offset = ((unsigned long)vmf->virtual_address - vma->vm_start) >>
                PAGE_SHIFT;

        /* Now bind it into the GTT if needed */
        mutex_lock(&dev->struct_mutex);

        if (!obj->map_and_fenceable) {
                ret = i915_gem_object_unbind(obj);
                if (ret)
                        goto unlock;
        }
        if (!obj->gtt_space) {
                ret = i915_gem_object_bind_to_gtt(obj, 0, true);
                if (ret)
                        goto unlock;
        }

        ret = i915_gem_object_set_to_gtt_domain(obj, write);
        if (ret)
                goto unlock;

        /* Need a new fence register? */
        if (obj->tiling_mode != I915_TILING_NONE) {
                ret = i915_gem_object_get_fence_reg(obj, true);
                if (ret)
                        goto unlock;
        }

        if (i915_gem_object_is_inactive(obj))
                list_move_tail(&obj->mm_list, &dev_priv->mm.inactive_list);

        obj->fault_mappable = true;

        pfn = ((dev->agp->base + obj->gtt_offset) >> PAGE_SHIFT) +
                page_offset;

        /* Finally, remap it using the new GTT offset */
        ret = vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);
unlock:
        mutex_unlock(&dev->struct_mutex);

        switch (ret) {
        case -EAGAIN:
                set_need_resched();
        case 0:
        case -ERESTARTSYS:
                return VM_FAULT_NOPAGE;
        case -ENOMEM:
                return VM_FAULT_OOM;
        default:
                return VM_FAULT_SIGBUS;
        }
}

/**
 * i915_gem_create_mmap_offset - create a fake mmap offset for an object
 * @obj: obj in question
 *
 * GEM memory mapping works by handing back to userspace a fake mmap offset
 * it can use in a subsequent mmap(2) call.  The DRM core code then looks
 * up the object based on the offset and sets up the various memory mapping
 * structures.
 *
 * This routine allocates and attaches a fake offset for @obj.
 */
static int
i915_gem_create_mmap_offset(struct drm_i915_gem_object *obj)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_gem_mm *mm = dev->mm_private;
        struct drm_map_list *list;
        struct drm_local_map *map;
        int ret = 0;

        /* Set the object up for mmap'ing */
        list = &obj->base.map_list;
        list->map = kzalloc(sizeof(struct drm_map_list), GFP_KERNEL);
        if (!list->map)
                return -ENOMEM;

        map = list->map;
        map->type = _DRM_GEM;
        map->size = obj->base.size;
        map->handle = obj;

        /* Get a DRM GEM mmap offset allocated... */
        list->file_offset_node = drm_mm_search_free(&mm->offset_manager,
                                                    obj->base.size / PAGE_SIZE,
                                                    0, 0);
        if (!list->file_offset_node) {
                DRM_ERROR("failed to allocate offset for bo %d\n",
                          obj->base.name);
                ret = -ENOSPC;
                goto out_free_list;
        }

        list->file_offset_node = drm_mm_get_block(list->file_offset_node,
                                                  obj->base.size / PAGE_SIZE,
                                                  0);
        if (!list->file_offset_node) {
                ret = -ENOMEM;
                goto out_free_list;
        }

        list->hash.key = list->file_offset_node->start;
        ret = drm_ht_insert_item(&mm->offset_hash, &list->hash);
        if (ret) {
                DRM_ERROR("failed to add to map hash\n");
                goto out_free_mm;
        }

        return 0;

out_free_mm:
        drm_mm_put_block(list->file_offset_node);
out_free_list:
        kfree(list->map);
        list->map = NULL;

        return ret;
}

/**
 * i915_gem_release_mmap - remove physical page mappings
 * @obj: obj in question
 *
 * Preserve the reservation of the mmapping with the DRM core code, but
 * relinquish ownership of the pages back to the system.
 *
 * It is vital that we remove the page mapping if we have mapped a tiled
 * object through the GTT and then lose the fence register due to
 * resource pressure. Similarly if the object has been moved out of the
 * aperture, than pages mapped into userspace must be revoked. Removing the
 * mapping will then trigger a page fault on the next user access, allowing
 * fixup by i915_gem_fault().
 */
void
i915_gem_release_mmap(struct drm_i915_gem_object *obj)
{
        if (!obj->fault_mappable)
                return;

        unmap_mapping_range(obj->base.dev->dev_mapping,
                            (loff_t)obj->base.map_list.hash.key<<PAGE_SHIFT,
                            obj->base.size, 1);

        obj->fault_mappable = false;
}

static void
i915_gem_free_mmap_offset(struct drm_i915_gem_object *obj)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_gem_mm *mm = dev->mm_private;
        struct drm_map_list *list = &obj->base.map_list;

        drm_ht_remove_item(&mm->offset_hash, &list->hash);
        drm_mm_put_block(list->file_offset_node);
        kfree(list->map);
        list->map = NULL;
}

static uint32_t
i915_gem_get_gtt_size(struct drm_i915_gem_object *obj)
{
        struct drm_device *dev = obj->base.dev;
        uint32_t size;

        if (INTEL_INFO(dev)->gen >= 4 ||
            obj->tiling_mode == I915_TILING_NONE)
                return obj->base.size;

        /* Previous chips need a power-of-two fence region when tiling */
        if (INTEL_INFO(dev)->gen == 3)
                size = 1024*1024;
        else
                size = 512*1024;

        while (size < obj->base.size)
                size <<= 1;

        return size;
}

/**
 * i915_gem_get_gtt_alignment - return required GTT alignment for an object
 * @obj: object to check
 *
 * Return the required GTT alignment for an object, taking into account
 * potential fence register mapping.
 */
static uint32_t
i915_gem_get_gtt_alignment(struct drm_i915_gem_object *obj)
{
        struct drm_device *dev = obj->base.dev;

        /*
         * Minimum alignment is 4k (GTT page size), but might be greater
         * if a fence register is needed for the object.
         */
        if (INTEL_INFO(dev)->gen >= 4 ||
            obj->tiling_mode == I915_TILING_NONE)
                return 4096;

        /*
         * Previous chips need to be aligned to the size of the smallest
         * fence register that can contain the object.
         */
        return i915_gem_get_gtt_size(obj);
}

/**
 * i915_gem_get_unfenced_gtt_alignment - return required GTT alignment for an
 *                                       unfenced object
 * @obj: object to check
 *
 * Return the required GTT alignment for an object, only taking into account
 * unfenced tiled surface requirements.
 */
static uint32_t
i915_gem_get_unfenced_gtt_alignment(struct drm_i915_gem_object *obj)
{
        struct drm_device *dev = obj->base.dev;
        int tile_height;

        /*
         * Minimum alignment is 4k (GTT page size) for sane hw.
         */
        if (INTEL_INFO(dev)->gen >= 4 || IS_G33(dev) ||
            obj->tiling_mode == I915_TILING_NONE)
                return 4096;

        /*
         * Older chips need unfenced tiled buffers to be aligned to the left
         * edge of an even tile row (where tile rows are counted as if the bo is
         * placed in a fenced gtt region).
         */
        if (IS_GEN2(dev) ||
            (obj->tiling_mode == I915_TILING_Y && HAS_128_BYTE_Y_TILING(dev)))
                tile_height = 32;
        else
                tile_height = 8;

        return tile_height * obj->stride * 2;
}

/**
 * i915_gem_mmap_gtt_ioctl - prepare an object for GTT mmap'ing
 * @dev: DRM device
 * @data: GTT mapping ioctl data
 * @file: GEM object info
 *
 * Simply returns the fake offset to userspace so it can mmap it.
 * The mmap call will end up in drm_gem_mmap(), which will set things
 * up so we can get faults in the handler above.
 *
 * The fault handler will take care of binding the object into the GTT
 * (since it may have been evicted to make room for something), allocating
 * a fence register, and mapping the appropriate aperture address into
 * userspace.
 */
int
i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_mmap_gtt *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        if (!(dev->driver->driver_features & DRIVER_GEM))
                return -ENODEV;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (obj == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        if (obj->base.size > dev_priv->mm.gtt_mappable_end) {
                ret = -E2BIG;
                goto unlock;
        }

        if (obj->madv != I915_MADV_WILLNEED) {
                DRM_ERROR("Attempting to mmap a purgeable buffer\n");
                ret = -EINVAL;
                goto out;
        }

        if (!obj->base.map_list.map) {
                ret = i915_gem_create_mmap_offset(obj);
                if (ret)
                        goto out;
        }

        args->offset = (u64)obj->base.map_list.hash.key << PAGE_SHIFT;

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

static int
i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj,
                              gfp_t gfpmask)
{
        int page_count, i;
        struct address_space *mapping;
        struct inode *inode;
        struct page *page;

        /* Get the list of pages out of our struct file.  They'll be pinned
         * at this point until we release them.
         */
        page_count = obj->base.size / PAGE_SIZE;
        BUG_ON(obj->pages != NULL);
        obj->pages = drm_malloc_ab(page_count, sizeof(struct page *));
        if (obj->pages == NULL)
                return -ENOMEM;

        inode = obj->base.filp->f_path.dentry->d_inode;
        mapping = inode->i_mapping;
        for (i = 0; i < page_count; i++) {
                page = read_cache_page_gfp(mapping, i,
                                           GFP_HIGHUSER |
                                           __GFP_COLD |
                                           __GFP_RECLAIMABLE |
                                           gfpmask);
                if (IS_ERR(page))
                        goto err_pages;

                obj->pages[i] = page;
        }

        if (obj->tiling_mode != I915_TILING_NONE)
                i915_gem_object_do_bit_17_swizzle(obj);

        return 0;

err_pages:
        while (i--)
                page_cache_release(obj->pages[i]);

        drm_free_large(obj->pages);
        obj->pages = NULL;
        return PTR_ERR(page);
}

static void
i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj)
{
        int page_count = obj->base.size / PAGE_SIZE;
        int i;

        BUG_ON(obj->madv == __I915_MADV_PURGED);

        if (obj->tiling_mode != I915_TILING_NONE)
                i915_gem_object_save_bit_17_swizzle(obj);

        if (obj->madv == I915_MADV_DONTNEED)
                obj->dirty = 0;

        for (i = 0; i < page_count; i++) {
                if (obj->dirty)
                        set_page_dirty(obj->pages[i]);

                if (obj->madv == I915_MADV_WILLNEED)
                        mark_page_accessed(obj->pages[i]);

                page_cache_release(obj->pages[i]);
        }
        obj->dirty = 0;

        drm_free_large(obj->pages);
        obj->pages = NULL;
}

void
i915_gem_object_move_to_active(struct drm_i915_gem_object *obj,
                               struct intel_ring_buffer *ring)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        uint32_t seqno = i915_gem_next_request_seqno(dev, ring);

        BUG_ON(ring == NULL);
        obj->ring = ring;

        /* Add a reference if we're newly entering the active list. */
        if (!obj->active) {
                drm_gem_object_reference(&obj->base);
                obj->active = 1;
        }

        /* Move from whatever list we were on to the tail of execution. */
        list_move_tail(&obj->mm_list, &dev_priv->mm.active_list);
        list_move_tail(&obj->ring_list, &ring->active_list);

        obj->last_rendering_seqno = seqno;
        if (obj->fenced_gpu_access) {
                struct drm_i915_fence_reg *reg;

                BUG_ON(obj->fence_reg == I915_FENCE_REG_NONE);

                obj->last_fenced_seqno = seqno;
                obj->last_fenced_ring = ring;

                reg = &dev_priv->fence_regs[obj->fence_reg];
                list_move_tail(&reg->lru_list, &dev_priv->mm.fence_list);
        }
}

static void
i915_gem_object_move_off_active(struct drm_i915_gem_object *obj)
{
        list_del_init(&obj->ring_list);
        obj->last_rendering_seqno = 0;
        obj->last_fenced_seqno = 0;
}

static void
i915_gem_object_move_to_flushing(struct drm_i915_gem_object *obj)
{
        struct drm_device *dev = obj->base.dev;
        drm_i915_private_t *dev_priv = dev->dev_private;

        BUG_ON(!obj->active);
        list_move_tail(&obj->mm_list, &dev_priv->mm.flushing_list);

        i915_gem_object_move_off_active(obj);
}

static void
i915_gem_object_move_to_inactive(struct drm_i915_gem_object *obj)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        if (obj->pin_count != 0)
                list_move_tail(&obj->mm_list, &dev_priv->mm.pinned_list);
        else
                list_move_tail(&obj->mm_list, &dev_priv->mm.inactive_list);

        BUG_ON(!list_empty(&obj->gpu_write_list));
        BUG_ON(!obj->active);
        obj->ring = NULL;

        i915_gem_object_move_off_active(obj);
        obj->fenced_gpu_access = false;
        obj->last_fenced_ring = NULL;

        obj->active = 0;
        drm_gem_object_unreference(&obj->base);

        WARN_ON(i915_verify_lists(dev));
}

/* Immediately discard the backing storage */
static void
i915_gem_object_truncate(struct drm_i915_gem_object *obj)
{
        struct inode *inode;

        /* Our goal here is to return as much of the memory as
         * is possible back to the system as we are called from OOM.
         * To do this we must instruct the shmfs to drop all of its
         * backing pages, *now*. Here we mirror the actions taken
         * when by shmem_delete_inode() to release the backing store.
         */
        inode = obj->base.filp->f_path.dentry->d_inode;
        truncate_inode_pages(inode->i_mapping, 0);
        if (inode->i_op->truncate_range)
                inode->i_op->truncate_range(inode, 0, (loff_t)-1);

        obj->madv = __I915_MADV_PURGED;
}

static inline int
i915_gem_object_is_purgeable(struct drm_i915_gem_object *obj)
{
        return obj->madv == I915_MADV_DONTNEED;
}

static void
i915_gem_process_flushing_list(struct drm_device *dev,
                               uint32_t flush_domains,
                               struct intel_ring_buffer *ring)
{
        struct drm_i915_gem_object *obj, *next;

        list_for_each_entry_safe(obj, next,
                                 &ring->gpu_write_list,
                                 gpu_write_list) {
                if (obj->base.write_domain & flush_domains) {
                        uint32_t old_write_domain = obj->base.write_domain;

                        obj->base.write_domain = 0;
                        list_del_init(&obj->gpu_write_list);
                        i915_gem_object_move_to_active(obj, ring);

                        trace_i915_gem_object_change_domain(obj,
                                                            obj->base.read_domains,
                                                            old_write_domain);
                }
        }
}

int
i915_add_request(struct drm_device *dev,
                 struct drm_file *file,
                 struct drm_i915_gem_request *request,
                 struct intel_ring_buffer *ring)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_file_private *file_priv = NULL;
        uint32_t seqno;
        int was_empty;
        int ret;

        BUG_ON(request == NULL);

        if (file != NULL)
                file_priv = file->driver_priv;

        ret = ring->add_request(ring, &seqno);
        if (ret)
            return ret;

        ring->outstanding_lazy_request = false;

        request->seqno = seqno;
        request->ring = ring;
        request->emitted_jiffies = jiffies;
        was_empty = list_empty(&ring->request_list);
        list_add_tail(&request->list, &ring->request_list);

        if (file_priv) {
                spin_lock(&file_priv->mm.lock);
                request->file_priv = file_priv;
                list_add_tail(&request->client_list,
                              &file_priv->mm.request_list);
                spin_unlock(&file_priv->mm.lock);
        }

        if (!dev_priv->mm.suspended) {
                mod_timer(&dev_priv->hangcheck_timer,
                          jiffies + msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
                if (was_empty)
                        queue_delayed_work(dev_priv->wq,
                                           &dev_priv->mm.retire_work, HZ);
        }
        return 0;
}

static inline void
i915_gem_request_remove_from_client(struct drm_i915_gem_request *request)
{
        struct drm_i915_file_private *file_priv = request->file_priv;

        if (!file_priv)
                return;

        spin_lock(&file_priv->mm.lock);
        list_del(&request->client_list);
        request->file_priv = NULL;
        spin_unlock(&file_priv->mm.lock);
}

static void i915_gem_reset_ring_lists(struct drm_i915_private *dev_priv,
                                      struct intel_ring_buffer *ring)
{
        while (!list_empty(&ring->request_list)) {
                struct drm_i915_gem_request *request;

                request = list_first_entry(&ring->request_list,
                                           struct drm_i915_gem_request,
                                           list);

                list_del(&request->list);
                i915_gem_request_remove_from_client(request);
                kfree(request);
        }

        while (!list_empty(&ring->active_list)) {
                struct drm_i915_gem_object *obj;

                obj = list_first_entry(&ring->active_list,
                                       struct drm_i915_gem_object,
                                       ring_list);

                obj->base.write_domain = 0;
                list_del_init(&obj->gpu_write_list);
                i915_gem_object_move_to_inactive(obj);
        }
}

static void i915_gem_reset_fences(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        int i;

        for (i = 0; i < 16; i++) {
                struct drm_i915_fence_reg *reg = &dev_priv->fence_regs[i];
                if (reg->obj)
                        i915_gem_clear_fence_reg(reg->obj);
        }
}

void i915_gem_reset(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj;

        i915_gem_reset_ring_lists(dev_priv, &dev_priv->render_ring);
        i915_gem_reset_ring_lists(dev_priv, &dev_priv->bsd_ring);
        i915_gem_reset_ring_lists(dev_priv, &dev_priv->blt_ring);

        /* Remove anything from the flushing lists. The GPU cache is likely
         * to be lost on reset along with the data, so simply move the
         * lost bo to the inactive list.
         */
        while (!list_empty(&dev_priv->mm.flushing_list)) {
                obj= list_first_entry(&dev_priv->mm.flushing_list,
                                      struct drm_i915_gem_object,
                                      mm_list);

                obj->base.write_domain = 0;
                list_del_init(&obj->gpu_write_list);
                i915_gem_object_move_to_inactive(obj);
        }

        /* Move everything out of the GPU domains to ensure we do any
         * necessary invalidation upon reuse.
         */
        list_for_each_entry(obj,
                            &dev_priv->mm.inactive_list,
                            mm_list)
        {
                obj->base.read_domains &= ~I915_GEM_GPU_DOMAINS;
        }

        /* The fence registers are invalidated so clear them out */
        i915_gem_reset_fences(dev);
}

/**
 * This function clears the request list as sequence numbers are passed.
 */
static void
i915_gem_retire_requests_ring(struct drm_device *dev,
                              struct intel_ring_buffer *ring)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        uint32_t seqno;

        if (!ring->status_page.page_addr ||
            list_empty(&ring->request_list))
                return;

        WARN_ON(i915_verify_lists(dev));

        seqno = ring->get_seqno(ring);
        while (!list_empty(&ring->request_list)) {
                struct drm_i915_gem_request *request;

                request = list_first_entry(&ring->request_list,
                                           struct drm_i915_gem_request,
                                           list);

                if (!i915_seqno_passed(seqno, request->seqno))
                        break;

                trace_i915_gem_request_retire(dev, request->seqno);

                list_del(&request->list);
                i915_gem_request_remove_from_client(request);
                kfree(request);
        }

        /* Move any buffers on the active list that are no longer referenced
         * by the ringbuffer to the flushing/inactive lists as appropriate.
         */
        while (!list_empty(&ring->active_list)) {
                struct drm_i915_gem_object *obj;

                obj= list_first_entry(&ring->active_list,
                                      struct drm_i915_gem_object,
                                      ring_list);

                if (!i915_seqno_passed(seqno, obj->last_rendering_seqno))
                        break;

                if (obj->base.write_domain != 0)
                        i915_gem_object_move_to_flushing(obj);
                else
                        i915_gem_object_move_to_inactive(obj);
        }

        if (unlikely (dev_priv->trace_irq_seqno &&
                      i915_seqno_passed(dev_priv->trace_irq_seqno, seqno))) {
                ring->user_irq_put(ring);
                dev_priv->trace_irq_seqno = 0;
        }

        WARN_ON(i915_verify_lists(dev));
}

void
i915_gem_retire_requests(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;

        if (!list_empty(&dev_priv->mm.deferred_free_list)) {
            struct drm_i915_gem_object *obj, *next;

            /* We must be careful that during unbind() we do not
             * accidentally infinitely recurse into retire requests.
             * Currently:
             *   retire -> free -> unbind -> wait -> retire_ring
             */
            list_for_each_entry_safe(obj, next,
                                     &dev_priv->mm.deferred_free_list,
                                     mm_list)
                    i915_gem_free_object_tail(obj);
        }

        i915_gem_retire_requests_ring(dev, &dev_priv->render_ring);
        i915_gem_retire_requests_ring(dev, &dev_priv->bsd_ring);
        i915_gem_retire_requests_ring(dev, &dev_priv->blt_ring);
}

static void
i915_gem_retire_work_handler(struct work_struct *work)
{
        drm_i915_private_t *dev_priv;
        struct drm_device *dev;

        dev_priv = container_of(work, drm_i915_private_t,
                                mm.retire_work.work);
        dev = dev_priv->dev;

        /* Come back later if the device is busy... */
        if (!mutex_trylock(&dev->struct_mutex)) {
                queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, HZ);
                return;
        }

        i915_gem_retire_requests(dev);

        if (!dev_priv->mm.suspended &&
                (!list_empty(&dev_priv->render_ring.request_list) ||
                 !list_empty(&dev_priv->bsd_ring.request_list) ||
                 !list_empty(&dev_priv->blt_ring.request_list)))
                queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, HZ);
        mutex_unlock(&dev->struct_mutex);
}

int
i915_do_wait_request(struct drm_device *dev, uint32_t seqno,
                     bool interruptible, struct intel_ring_buffer *ring)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        u32 ier;
        int ret = 0;

        BUG_ON(seqno == 0);

        if (atomic_read(&dev_priv->mm.wedged))
                return -EAGAIN;

        if (seqno == ring->outstanding_lazy_request) {
                struct drm_i915_gem_request *request;

                request = kzalloc(sizeof(*request), GFP_KERNEL);
                if (request == NULL)
                        return -ENOMEM;

                ret = i915_add_request(dev, NULL, request, ring);
                if (ret) {
                        kfree(request);
                        return ret;
                }

                seqno = request->seqno;
        }

        if (!i915_seqno_passed(ring->get_seqno(ring), seqno)) {
                if (HAS_PCH_SPLIT(dev))
                        ier = I915_READ(DEIER) | I915_READ(GTIER);
                else
                        ier = I915_READ(IER);
                if (!ier) {
                        DRM_ERROR("something (likely vbetool) disabled "
                                  "interrupts, re-enabling\n");
                        i915_driver_irq_preinstall(dev);
                        i915_driver_irq_postinstall(dev);
                }

                trace_i915_gem_request_wait_begin(dev, seqno);

                ring->waiting_seqno = seqno;
                ring->user_irq_get(ring);
                if (interruptible)
                        ret = wait_event_interruptible(ring->irq_queue,
                                i915_seqno_passed(ring->get_seqno(ring), seqno)
                                || atomic_read(&dev_priv->mm.wedged));
                else
                        wait_event(ring->irq_queue,
                                i915_seqno_passed(ring->get_seqno(ring), seqno)
                                || atomic_read(&dev_priv->mm.wedged));

                ring->user_irq_put(ring);
                ring->waiting_seqno = 0;

                trace_i915_gem_request_wait_end(dev, seqno);
        }
        if (atomic_read(&dev_priv->mm.wedged))
                ret = -EAGAIN;

        if (ret && ret != -ERESTARTSYS)
                DRM_ERROR("%s returns %d (awaiting %d at %d, next %d)\n",
                          __func__, ret, seqno, ring->get_seqno(ring),
                          dev_priv->next_seqno);

        /* Directly dispatch request retiring.  While we have the work queue
         * to handle this, the waiter on a request often wants an associated
         * buffer to have made it to the inactive list, and we would need
         * a separate wait queue to handle that.
         */
        if (ret == 0)
                i915_gem_retire_requests_ring(dev, ring);

        return ret;
}

/**
 * Waits for a sequence number to be signaled, and cleans up the
 * request and object lists appropriately for that event.
 */
static int
i915_wait_request(struct drm_device *dev, uint32_t seqno,
                  struct intel_ring_buffer *ring)
{
        return i915_do_wait_request(dev, seqno, 1, ring);
}

/**
 * Ensures that all rendering to the object has completed and the object is
 * safe to unbind from the GTT or access from the CPU.
 */
int
i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
                               bool interruptible)
{
        struct drm_device *dev = obj->base.dev;
        int ret;

        /* This function only exists to support waiting for existing rendering,
         * not for emitting required flushes.
         */
        BUG_ON((obj->base.write_domain & I915_GEM_GPU_DOMAINS) != 0);

        /* If there is rendering queued on the buffer being evicted, wait for
         * it.
         */
        if (obj->active) {
                ret = i915_do_wait_request(dev,
                                           obj->last_rendering_seqno,
                                           interruptible,
                                           obj->ring);
                if (ret)
                        return ret;
        }

        return 0;
}

/**
 * Unbinds an object from the GTT aperture.
 */
int
i915_gem_object_unbind(struct drm_i915_gem_object *obj)
{
        int ret = 0;

        if (obj->gtt_space == NULL)
                return 0;

        if (obj->pin_count != 0) {
                DRM_ERROR("Attempting to unbind pinned buffer\n");
                return -EINVAL;
        }

        /* blow away mappings if mapped through GTT */
        i915_gem_release_mmap(obj);

        /* Move the object to the CPU domain to ensure that
         * any possible CPU writes while it's not in the GTT
         * are flushed when we go to remap it. This will
         * also ensure that all pending GPU writes are finished
         * before we unbind.
         */
        ret = i915_gem_object_set_to_cpu_domain(obj, 1);
        if (ret == -ERESTARTSYS)
                return ret;
        /* Continue on if we fail due to EIO, the GPU is hung so we
         * should be safe and we need to cleanup or else we might
         * cause memory corruption through use-after-free.
         */
        if (ret) {
                i915_gem_clflush_object(obj);
                obj->base.read_domains = obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        }

        /* release the fence reg _after_ flushing */
        if (obj->fence_reg != I915_FENCE_REG_NONE)
                i915_gem_clear_fence_reg(obj);

        i915_gem_gtt_unbind_object(obj);
        i915_gem_object_put_pages_gtt(obj);

        list_del_init(&obj->gtt_list);
        list_del_init(&obj->mm_list);
        /* Avoid an unnecessary call to unbind on rebind. */
        obj->map_and_fenceable = true;

        drm_mm_put_block(obj->gtt_space);
        obj->gtt_space = NULL;
        obj->gtt_offset = 0;

        if (i915_gem_object_is_purgeable(obj))
                i915_gem_object_truncate(obj);

        trace_i915_gem_object_unbind(obj);

        return ret;
}

void
i915_gem_flush_ring(struct drm_device *dev,
                    struct intel_ring_buffer *ring,
                    uint32_t invalidate_domains,
                    uint32_t flush_domains)
{
        ring->flush(ring, invalidate_domains, flush_domains);
        i915_gem_process_flushing_list(dev, flush_domains, ring);
}

static int i915_ring_idle(struct drm_device *dev,
                          struct intel_ring_buffer *ring)
{
        if (list_empty(&ring->gpu_write_list) && list_empty(&ring->active_list))
                return 0;

        i915_gem_flush_ring(dev, ring,
                            I915_GEM_GPU_DOMAINS, I915_GEM_GPU_DOMAINS);
        return i915_wait_request(dev,
                                 i915_gem_next_request_seqno(dev, ring),
                                 ring);
}

int
i915_gpu_idle(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        bool lists_empty;
        int ret;

        lists_empty = (list_empty(&dev_priv->mm.flushing_list) &&
                       list_empty(&dev_priv->mm.active_list));
        if (lists_empty)
                return 0;

        /* Flush everything onto the inactive list. */
        ret = i915_ring_idle(dev, &dev_priv->render_ring);
        if (ret)
                return ret;

        ret = i915_ring_idle(dev, &dev_priv->bsd_ring);
        if (ret)
                return ret;

        ret = i915_ring_idle(dev, &dev_priv->blt_ring);
        if (ret)
                return ret;

        return 0;
}

static int sandybridge_write_fence_reg(struct drm_i915_gem_object *obj,
                                       struct intel_ring_buffer *pipelined)
{
        struct drm_device *dev = obj->base.dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        u32 size = obj->gtt_space->size;
        int regnum = obj->fence_reg;
        uint64_t val;

        val = (uint64_t)((obj->gtt_offset + size - 4096) &
                         0xfffff000) << 32;
        val |= obj->gtt_offset & 0xfffff000;
        val |= (uint64_t)((obj->stride / 128) - 1) <<
                SANDYBRIDGE_FENCE_PITCH_SHIFT;

        if (obj->tiling_mode == I915_TILING_Y)
                val |= 1 << I965_FENCE_TILING_Y_SHIFT;
        val |= I965_FENCE_REG_VALID;

        if (pipelined) {
                int ret = intel_ring_begin(pipelined, 6);
                if (ret)
                        return ret;

                intel_ring_emit(pipelined, MI_NOOP);
                intel_ring_emit(pipelined, MI_LOAD_REGISTER_IMM(2));
                intel_ring_emit(pipelined, FENCE_REG_SANDYBRIDGE_0 + regnum*8);
                intel_ring_emit(pipelined, (u32)val);
                intel_ring_emit(pipelined, FENCE_REG_SANDYBRIDGE_0 + regnum*8 + 4);
                intel_ring_emit(pipelined, (u32)(val >> 32));
                intel_ring_advance(pipelined);
        } else
                I915_WRITE64(FENCE_REG_SANDYBRIDGE_0 + regnum * 8, val);

        return 0;
}

static int i965_write_fence_reg(struct drm_i915_gem_object *obj,
                                struct intel_ring_buffer *pipelined)
{
        struct drm_device *dev = obj->base.dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        u32 size = obj->gtt_space->size;
        int regnum = obj->fence_reg;
        uint64_t val;

        val = (uint64_t)((obj->gtt_offset + size - 4096) &
                    0xfffff000) << 32;
        val |= obj->gtt_offset & 0xfffff000;
        val |= ((obj->stride / 128) - 1) << I965_FENCE_PITCH_SHIFT;
        if (obj->tiling_mode == I915_TILING_Y)
                val |= 1 << I965_FENCE_TILING_Y_SHIFT;
        val |= I965_FENCE_REG_VALID;

        if (pipelined) {
                int ret = intel_ring_begin(pipelined, 6);
                if (ret)
                        return ret;

                intel_ring_emit(pipelined, MI_NOOP);
                intel_ring_emit(pipelined, MI_LOAD_REGISTER_IMM(2));
                intel_ring_emit(pipelined, FENCE_REG_965_0 + regnum*8);
                intel_ring_emit(pipelined, (u32)val);
                intel_ring_emit(pipelined, FENCE_REG_965_0 + regnum*8 + 4);
                intel_ring_emit(pipelined, (u32)(val >> 32));
                intel_ring_advance(pipelined);
        } else
                I915_WRITE64(FENCE_REG_965_0 + regnum * 8, val);

        return 0;
}

static int i915_write_fence_reg(struct drm_i915_gem_object *obj,
                                struct intel_ring_buffer *pipelined)
{
        struct drm_device *dev = obj->base.dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        u32 size = obj->gtt_space->size;
        u32 fence_reg, val, pitch_val;
        int tile_width;

        if (WARN((obj->gtt_offset & ~I915_FENCE_START_MASK) ||
                 (size & -size) != size ||
                 (obj->gtt_offset & (size - 1)),
                 "object 0x%08x [fenceable? %d] not 1M or pot-size (0x%08x) aligned\n",
                 obj->gtt_offset, obj->map_and_fenceable, size))
                return -EINVAL;

        if (obj->tiling_mode == I915_TILING_Y && HAS_128_BYTE_Y_TILING(dev))
                tile_width = 128;
        else
                tile_width = 512;

        /* Note: pitch better be a power of two tile widths */
        pitch_val = obj->stride / tile_width;
        pitch_val = ffs(pitch_val) - 1;

        val = obj->gtt_offset;
        if (obj->tiling_mode == I915_TILING_Y)
                val |= 1 << I830_FENCE_TILING_Y_SHIFT;
        val |= I915_FENCE_SIZE_BITS(size);
        val |= pitch_val << I830_FENCE_PITCH_SHIFT;
        val |= I830_FENCE_REG_VALID;

        fence_reg = obj->fence_reg;
        if (fence_reg < 8)
                fence_reg = FENCE_REG_830_0 + fence_reg * 4;
        else
                fence_reg = FENCE_REG_945_8 + (fence_reg - 8) * 4;

        if (pipelined) {
                int ret = intel_ring_begin(pipelined, 4);
                if (ret)
                        return ret;

                intel_ring_emit(pipelined, MI_NOOP);
                intel_ring_emit(pipelined, MI_LOAD_REGISTER_IMM(1));
                intel_ring_emit(pipelined, fence_reg);
                intel_ring_emit(pipelined, val);
                intel_ring_advance(pipelined);
        } else
                I915_WRITE(fence_reg, val);

        return 0;
}

static int i830_write_fence_reg(struct drm_i915_gem_object *obj,
                                struct intel_ring_buffer *pipelined)
{
        struct drm_device *dev = obj->base.dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        u32 size = obj->gtt_space->size;
        int regnum = obj->fence_reg;
        uint32_t val;
        uint32_t pitch_val;

        if (WARN((obj->gtt_offset & ~I830_FENCE_START_MASK) ||
                 (size & -size) != size ||
                 (obj->gtt_offset & (size - 1)),
                 "object 0x%08x not 512K or pot-size 0x%08x aligned\n",
                 obj->gtt_offset, size))
                return -EINVAL;

        pitch_val = obj->stride / 128;
        pitch_val = ffs(pitch_val) - 1;

        val = obj->gtt_offset;
        if (obj->tiling_mode == I915_TILING_Y)
                val |= 1 << I830_FENCE_TILING_Y_SHIFT;
        val |= I830_FENCE_SIZE_BITS(size);
        val |= pitch_val << I830_FENCE_PITCH_SHIFT;
        val |= I830_FENCE_REG_VALID;

        if (pipelined) {
                int ret = intel_ring_begin(pipelined, 4);
                if (ret)
                        return ret;

                intel_ring_emit(pipelined, MI_NOOP);
                intel_ring_emit(pipelined, MI_LOAD_REGISTER_IMM(1));
                intel_ring_emit(pipelined, FENCE_REG_830_0 + regnum*4);
                intel_ring_emit(pipelined, val);
                intel_ring_advance(pipelined);
        } else
                I915_WRITE(FENCE_REG_830_0 + regnum * 4, val);

        return 0;
}

static int i915_find_fence_reg(struct drm_device *dev,
                               bool interruptible)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_fence_reg *reg;
        struct drm_i915_gem_object *obj = NULL;
        int i, avail, ret;

        /* First try to find a free reg */
        avail = 0;
        for (i = dev_priv->fence_reg_start; i < dev_priv->num_fence_regs; i++) {
                reg = &dev_priv->fence_regs[i];
                if (!reg->obj)
                        return i;

                if (!reg->obj->pin_count)
                        avail++;
        }

        if (avail == 0)
                return -ENOSPC;

        /* None available, try to steal one or wait for a user to finish */
        avail = I915_FENCE_REG_NONE;
        list_for_each_entry(reg, &dev_priv->mm.fence_list,
                            lru_list) {
                obj = reg->obj;
                if (obj->pin_count)
                        continue;

                /* found one! */
                avail = obj->fence_reg;
                break;
        }

        BUG_ON(avail == I915_FENCE_REG_NONE);

        /* We only have a reference on obj from the active list. put_fence_reg
         * might drop that one, causing a use-after-free in it. So hold a
         * private reference to obj like the other callers of put_fence_reg
         * (set_tiling ioctl) do. */
        drm_gem_object_reference(&obj->base);
        ret = i915_gem_object_put_fence_reg(obj, interruptible);
        drm_gem_object_unreference(&obj->base);
        if (ret != 0)
                return ret;

        return avail;
}

/**
 * i915_gem_object_get_fence_reg - set up a fence reg for an object
 * @obj: object to map through a fence reg
 *
 * When mapping objects through the GTT, userspace wants to be able to write
 * to them without having to worry about swizzling if the object is tiled.
 *
 * This function walks the fence regs looking for a free one for @obj,
 * stealing one if it can't find any.
 *
 * It then sets up the reg based on the object's properties: address, pitch
 * and tiling format.
 */
int
i915_gem_object_get_fence_reg(struct drm_i915_gem_object *obj,
                              bool interruptible)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_fence_reg *reg = NULL;
        struct intel_ring_buffer *pipelined = NULL;
        int ret;

        /* Just update our place in the LRU if our fence is getting used. */
        if (obj->fence_reg != I915_FENCE_REG_NONE) {
                reg = &dev_priv->fence_regs[obj->fence_reg];
                list_move_tail(&reg->lru_list, &dev_priv->mm.fence_list);
                return 0;
        }

        switch (obj->tiling_mode) {
        case I915_TILING_NONE:
                WARN(1, "allocating a fence for non-tiled object?\n");
                break;
        case I915_TILING_X:
                if (!obj->stride)
                        return -EINVAL;
                WARN((obj->stride & (512 - 1)),
                     "object 0x%08x is X tiled but has non-512B pitch\n",
                     obj->gtt_offset);
                break;
        case I915_TILING_Y:
                if (!obj->stride)
                        return -EINVAL;
                WARN((obj->stride & (128 - 1)),
                     "object 0x%08x is Y tiled but has non-128B pitch\n",
                     obj->gtt_offset);
                break;
        }

        ret = i915_find_fence_reg(dev, interruptible);
        if (ret < 0)
                return ret;

        obj->fence_reg = ret;
        reg = &dev_priv->fence_regs[obj->fence_reg];
        list_add_tail(&reg->lru_list, &dev_priv->mm.fence_list);

        reg->obj = obj;

        switch (INTEL_INFO(dev)->gen) {
        case 6:
                ret = sandybridge_write_fence_reg(obj, pipelined);
                break;
        case 5:
        case 4:
                ret = i965_write_fence_reg(obj, pipelined);
                break;
        case 3:
                ret = i915_write_fence_reg(obj, pipelined);
                break;
        case 2:
                ret = i830_write_fence_reg(obj, pipelined);
                break;
        }

        trace_i915_gem_object_get_fence(obj,
                                        obj->fence_reg,
                                        obj->tiling_mode);
        return ret;
}

/**
 * i915_gem_clear_fence_reg - clear out fence register info
 * @obj: object to clear
 *
 * Zeroes out the fence register itself and clears out the associated
 * data structures in dev_priv and obj.
 */
static void
i915_gem_clear_fence_reg(struct drm_i915_gem_object *obj)
{
        struct drm_device *dev = obj->base.dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_fence_reg *reg = &dev_priv->fence_regs[obj->fence_reg];
        uint32_t fence_reg;

        switch (INTEL_INFO(dev)->gen) {
        case 6:
                I915_WRITE64(FENCE_REG_SANDYBRIDGE_0 +
                             (obj->fence_reg * 8), 0);
                break;
        case 5:
        case 4:
                I915_WRITE64(FENCE_REG_965_0 + (obj->fence_reg * 8), 0);
                break;
        case 3:
                if (obj->fence_reg >= 8)
                        fence_reg = FENCE_REG_945_8 + (obj->fence_reg - 8) * 4;
                else
        case 2:
                        fence_reg = FENCE_REG_830_0 + obj->fence_reg * 4;

                I915_WRITE(fence_reg, 0);
                break;
        }

        reg->obj = NULL;
        obj->fence_reg = I915_FENCE_REG_NONE;
        list_del_init(&reg->lru_list);
}

/**
 * i915_gem_object_put_fence_reg - waits on outstanding fenced access
 * to the buffer to finish, and then resets the fence register.
 * @obj: tiled object holding a fence register.
 * @bool: whether the wait upon the fence is interruptible
 *
 * Zeroes out the fence register itself and clears out the associated
 * data structures in dev_priv and obj.
 */
int
i915_gem_object_put_fence_reg(struct drm_i915_gem_object *obj,
                              bool interruptible)
{
        struct drm_device *dev = obj->base.dev;
        int ret;

        if (obj->fence_reg == I915_FENCE_REG_NONE)
                return 0;

        /* If we've changed tiling, GTT-mappings of the object
         * need to re-fault to ensure that the correct fence register
         * setup is in place.
         */
        i915_gem_release_mmap(obj);

        /* On the i915, GPU access to tiled buffers is via a fence,
         * therefore we must wait for any outstanding access to complete
         * before clearing the fence.
         */
        if (obj->fenced_gpu_access) {
                ret = i915_gem_object_flush_gpu_write_domain(obj, NULL);
                if (ret)
                        return ret;

                obj->fenced_gpu_access = false;
        }

        if (obj->last_fenced_seqno) {
                ret = i915_do_wait_request(dev,
                                           obj->last_fenced_seqno,
                                           interruptible,
                                           obj->last_fenced_ring);
                if (ret)
                        return ret;

                obj->last_fenced_seqno = false;
        }

        i915_gem_object_flush_gtt_write_domain(obj);
        i915_gem_clear_fence_reg(obj);

        return 0;
}

/**
 * Finds free space in the GTT aperture and binds the object there.
 */
static int
i915_gem_object_bind_to_gtt(struct drm_i915_gem_object *obj,
                            unsigned alignment,
                            bool map_and_fenceable)
{
        struct drm_device *dev = obj->base.dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_mm_node *free_space;
        gfp_t gfpmask = __GFP_NORETRY | __GFP_NOWARN;
        u32 size, fence_size, fence_alignment, unfenced_alignment;
        bool mappable, fenceable;
        int ret;

        if (obj->madv != I915_MADV_WILLNEED) {
                DRM_ERROR("Attempting to bind a purgeable object\n");
                return -EINVAL;
        }

        fence_size = i915_gem_get_gtt_size(obj);
        fence_alignment = i915_gem_get_gtt_alignment(obj);
        unfenced_alignment = i915_gem_get_unfenced_gtt_alignment(obj);

        if (alignment == 0)
                alignment = map_and_fenceable ? fence_alignment :
                                                unfenced_alignment;
        if (map_and_fenceable && alignment & (fence_alignment - 1)) {
                DRM_ERROR("Invalid object alignment requested %u\n", alignment);
                return -EINVAL;
        }

        size = map_and_fenceable ? fence_size : obj->base.size;

        /* If the object is bigger than the entire aperture, reject it early
         * before evicting everything in a vain attempt to find space.
         */
        if (obj->base.size >
            (map_and_fenceable ? dev_priv->mm.gtt_mappable_end : dev_priv->mm.gtt_total)) {
                DRM_ERROR("Attempting to bind an object larger than the aperture\n");
                return -E2BIG;
        }

 search_free:
        if (map_and_fenceable)
                free_space =
                        drm_mm_search_free_in_range(&dev_priv->mm.gtt_space,
                                                    size, alignment, 0,
                                                    dev_priv->mm.gtt_mappable_end,
                                                    0);
        else
                free_space = drm_mm_search_free(&dev_priv->mm.gtt_space,
                                                size, alignment, 0);

        if (free_space != NULL) {
                if (map_and_fenceable)
                        obj->gtt_space =
                                drm_mm_get_block_range_generic(free_space,
                                                               size, alignment, 0,
                                                               dev_priv->mm.gtt_mappable_end,
                                                               0);
                else
                        obj->gtt_space =
                                drm_mm_get_block(free_space, size, alignment);
        }
        if (obj->gtt_space == NULL) {
                /* If the gtt is empty and we're still having trouble
                 * fitting our object in, we're out of memory.
                 */
                ret = i915_gem_evict_something(dev, size, alignment,
                                               map_and_fenceable);
                if (ret)
                        return ret;

                goto search_free;
        }

        ret = i915_gem_object_get_pages_gtt(obj, gfpmask);
        if (ret) {
                drm_mm_put_block(obj->gtt_space);
                obj->gtt_space = NULL;

                if (ret == -ENOMEM) {
                        /* first try to clear up some space from the GTT */
                        ret = i915_gem_evict_something(dev, size,
                                                       alignment,
                                                       map_and_fenceable);
                        if (ret) {
                                /* now try to shrink everyone else */
                                if (gfpmask) {
                                        gfpmask = 0;
                                        goto search_free;
                                }

                                return ret;
                        }

                        goto search_free;
                }

                return ret;
        }

        ret = i915_gem_gtt_bind_object(obj);
        if (ret) {
                i915_gem_object_put_pages_gtt(obj);
                drm_mm_put_block(obj->gtt_space);
                obj->gtt_space = NULL;

                ret = i915_gem_evict_something(dev, size,
                                               alignment, map_and_fenceable);
                if (ret)
                        return ret;

                goto search_free;
        }

        list_add_tail(&obj->gtt_list, &dev_priv->mm.gtt_list);
        list_add_tail(&obj->mm_list, &dev_priv->mm.inactive_list);

        /* Assert that the object is not currently in any GPU domain. As it
         * wasn't in the GTT, there shouldn't be any way it could have been in
         * a GPU cache
         */
        BUG_ON(obj->base.read_domains & I915_GEM_GPU_DOMAINS);
        BUG_ON(obj->base.write_domain & I915_GEM_GPU_DOMAINS);

        obj->gtt_offset = obj->gtt_space->start;

        fenceable =
                obj->gtt_space->size == fence_size &&
                (obj->gtt_space->start & (fence_alignment -1)) == 0;

        mappable =
                obj->gtt_offset + obj->base.size <= dev_priv->mm.gtt_mappable_end;

        obj->map_and_fenceable = mappable && fenceable;

        trace_i915_gem_object_bind(obj, obj->gtt_offset, map_and_fenceable);
        return 0;
}

void
i915_gem_clflush_object(struct drm_i915_gem_object *obj)
{
        /* If we don't have a page list set up, then we're not pinned
         * to GPU, and we can ignore the cache flush because it'll happen
         * again at bind time.
         */
        if (obj->pages == NULL)
                return;

        trace_i915_gem_object_clflush(obj);

        drm_clflush_pages(obj->pages, obj->base.size / PAGE_SIZE);
}

/** Flushes any GPU write domain for the object if it's dirty. */
static int
i915_gem_object_flush_gpu_write_domain(struct drm_i915_gem_object *obj,
                                       struct intel_ring_buffer *pipelined)
{
        struct drm_device *dev = obj->base.dev;

        if ((obj->base.write_domain & I915_GEM_GPU_DOMAINS) == 0)
                return 0;

        /* Queue the GPU write cache flushing we need. */
        i915_gem_flush_ring(dev, obj->ring, 0, obj->base.write_domain);
        BUG_ON(obj->base.write_domain);

        if (pipelined && pipelined == obj->ring)
                return 0;

        return i915_gem_object_wait_rendering(obj, true);
}

/** Flushes the GTT write domain for the object if it's dirty. */
static void
i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj)
{
        uint32_t old_write_domain;

        if (obj->base.write_domain != I915_GEM_DOMAIN_GTT)
                return;

        /* No actual flushing is required for the GTT write domain.   Writes
         * to it immediately go to main memory as far as we know, so there's
         * no chipset flush.  It also doesn't land in render cache.
         */
        i915_gem_release_mmap(obj);

        old_write_domain = obj->base.write_domain;
        obj->base.write_domain = 0;

        trace_i915_gem_object_change_domain(obj,
                                            obj->base.read_domains,
                                            old_write_domain);
}

/** Flushes the CPU write domain for the object if it's dirty. */
static void
i915_gem_object_flush_cpu_write_domain(struct drm_i915_gem_object *obj)
{
        uint32_t old_write_domain;

        if (obj->base.write_domain != I915_GEM_DOMAIN_CPU)
                return;

        i915_gem_clflush_object(obj);
        intel_gtt_chipset_flush();
        old_write_domain = obj->base.write_domain;
        obj->base.write_domain = 0;

        trace_i915_gem_object_change_domain(obj,
                                            obj->base.read_domains,
                                            old_write_domain);
}

/**
 * Moves a single object to the GTT read, and possibly write domain.
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
int
i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write)
{
        uint32_t old_write_domain, old_read_domains;
        int ret;

        /* Not valid to be called on unbound objects. */
        if (obj->gtt_space == NULL)
                return -EINVAL;

        ret = i915_gem_object_flush_gpu_write_domain(obj, NULL);
        if (ret != 0)
                return ret;

        i915_gem_object_flush_cpu_write_domain(obj);

        if (write) {
                ret = i915_gem_object_wait_rendering(obj, true);
                if (ret)
                        return ret;
        }

        old_write_domain = obj->base.write_domain;
        old_read_domains = obj->base.read_domains;

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->base.write_domain & ~I915_GEM_DOMAIN_GTT) != 0);
        obj->base.read_domains |= I915_GEM_DOMAIN_GTT;
        if (write) {
                obj->base.read_domains = I915_GEM_DOMAIN_GTT;
                obj->base.write_domain = I915_GEM_DOMAIN_GTT;
                obj->dirty = 1;
        }

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            old_write_domain);

        return 0;
}

/*
 * Prepare buffer for display plane. Use uninterruptible for possible flush
 * wait, as in modesetting process we're not supposed to be interrupted.
 */
int
i915_gem_object_set_to_display_plane(struct drm_i915_gem_object *obj,
                                     struct intel_ring_buffer *pipelined)
{
        uint32_t old_read_domains;
        int ret;

        /* Not valid to be called on unbound objects. */
        if (obj->gtt_space == NULL)
                return -EINVAL;

        ret = i915_gem_object_flush_gpu_write_domain(obj, pipelined);
        if (ret)
                return ret;

        /* Currently, we are always called from an non-interruptible context. */
        if (!pipelined) {
                ret = i915_gem_object_wait_rendering(obj, false);
                if (ret)
                        return ret;
        }

        i915_gem_object_flush_cpu_write_domain(obj);

        old_read_domains = obj->base.read_domains;
        obj->base.read_domains |= I915_GEM_DOMAIN_GTT;

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            obj->base.write_domain);

        return 0;
}

int
i915_gem_object_flush_gpu(struct drm_i915_gem_object *obj,
                          bool interruptible)
{
        if (!obj->active)
                return 0;

        if (obj->base.write_domain & I915_GEM_GPU_DOMAINS)
                i915_gem_flush_ring(obj->base.dev, obj->ring,
                                    0, obj->base.write_domain);

        return i915_gem_object_wait_rendering(obj, interruptible);
}

/**
 * Moves a single object to the CPU read, and possibly write domain.
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
static int
i915_gem_object_set_to_cpu_domain(struct drm_i915_gem_object *obj, bool write)
{
        uint32_t old_write_domain, old_read_domains;
        int ret;

        ret = i915_gem_object_flush_gpu_write_domain(obj, false);
        if (ret != 0)
                return ret;

        i915_gem_object_flush_gtt_write_domain(obj);

        /* If we have a partially-valid cache of the object in the CPU,
         * finish invalidating it and free the per-page flags.
         */
        i915_gem_object_set_to_full_cpu_read_domain(obj);

        if (write) {
                ret = i915_gem_object_wait_rendering(obj, true);
                if (ret)
                        return ret;
        }

        old_write_domain = obj->base.write_domain;
        old_read_domains = obj->base.read_domains;

        /* Flush the CPU cache if it's still invalid. */
        if ((obj->base.read_domains & I915_GEM_DOMAIN_CPU) == 0) {
                i915_gem_clflush_object(obj);

                obj->base.read_domains |= I915_GEM_DOMAIN_CPU;
        }

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->base.write_domain & ~I915_GEM_DOMAIN_CPU) != 0);

        /* If we're writing through the CPU, then the GPU read domains will
         * need to be invalidated at next use.
         */
        if (write) {
                obj->base.read_domains = I915_GEM_DOMAIN_CPU;
                obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        }

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            old_write_domain);

        return 0;
}

/**
 * Moves the object from a partially CPU read to a full one.
 *
 * Note that this only resolves i915_gem_object_set_cpu_read_domain_range(),
 * and doesn't handle transitioning from !(read_domains & I915_GEM_DOMAIN_CPU).
 */
static void
i915_gem_object_set_to_full_cpu_read_domain(struct drm_i915_gem_object *obj)
{
        if (!obj->page_cpu_valid)
                return;

        /* If we're partially in the CPU read domain, finish moving it in.
         */
        if (obj->base.read_domains & I915_GEM_DOMAIN_CPU) {
                int i;

                for (i = 0; i <= (obj->base.size - 1) / PAGE_SIZE; i++) {
                        if (obj->page_cpu_valid[i])
                                continue;
                        drm_clflush_pages(obj->pages + i, 1);
                }
        }

        /* Free the page_cpu_valid mappings which are now stale, whether
         * or not we've got I915_GEM_DOMAIN_CPU.
         */
        kfree(obj->page_cpu_valid);
        obj->page_cpu_valid = NULL;
}

/**
 * Set the CPU read domain on a range of the object.
 *
 * The object ends up with I915_GEM_DOMAIN_CPU in its read flags although it's
 * not entirely valid.  The page_cpu_valid member of the object flags which
 * pages have been flushed, and will be respected by
 * i915_gem_object_set_to_cpu_domain() if it's called on to get a valid mapping
 * of the whole object.
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
static int
i915_gem_object_set_cpu_read_domain_range(struct drm_i915_gem_object *obj,
                                          uint64_t offset, uint64_t size)
{
        uint32_t old_read_domains;
        int i, ret;

        if (offset == 0 && size == obj->base.size)
                return i915_gem_object_set_to_cpu_domain(obj, 0);

        ret = i915_gem_object_flush_gpu_write_domain(obj, false);
        if (ret != 0)
                return ret;
        i915_gem_object_flush_gtt_write_domain(obj);

        /* If we're already fully in the CPU read domain, we're done. */
        if (obj->page_cpu_valid == NULL &&
            (obj->base.read_domains & I915_GEM_DOMAIN_CPU) != 0)
                return 0;

        /* Otherwise, create/clear the per-page CPU read domain flag if we're
         * newly adding I915_GEM_DOMAIN_CPU
         */
        if (obj->page_cpu_valid == NULL) {
                obj->page_cpu_valid = kzalloc(obj->base.size / PAGE_SIZE,
                                              GFP_KERNEL);
                if (obj->page_cpu_valid == NULL)
                        return -ENOMEM;
        } else if ((obj->base.read_domains & I915_GEM_DOMAIN_CPU) == 0)
                memset(obj->page_cpu_valid, 0, obj->base.size / PAGE_SIZE);

        /* Flush the cache on any pages that are still invalid from the CPU's
         * perspective.
         */
        for (i = offset / PAGE_SIZE; i <= (offset + size - 1) / PAGE_SIZE;
             i++) {
                if (obj->page_cpu_valid[i])
                        continue;

                drm_clflush_pages(obj->pages + i, 1);

                obj->page_cpu_valid[i] = 1;
        }

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->base.write_domain & ~I915_GEM_DOMAIN_CPU) != 0);

        old_read_domains = obj->base.read_domains;
        obj->base.read_domains |= I915_GEM_DOMAIN_CPU;

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            obj->base.write_domain);

        return 0;
}

/* Throttle our rendering by waiting until the ring has completed our requests
 * emitted over 20 msec ago.
 *
 * Note that if we were to use the current jiffies each time around the loop,
 * we wouldn't escape the function with any frames outstanding if the time to
 * render a frame was over 20ms.
 *
 * This should get us reasonable parallelism between CPU and GPU but also
 * relatively low latency when blocking on a particular request to finish.
 */
static int
i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_file_private *file_priv = file->driver_priv;
        unsigned long recent_enough = jiffies - msecs_to_jiffies(20);
        struct drm_i915_gem_request *request;
        struct intel_ring_buffer *ring = NULL;
        u32 seqno = 0;
        int ret;

        spin_lock(&file_priv->mm.lock);
        list_for_each_entry(request, &file_priv->mm.request_list, client_list) {
                if (time_after_eq(request->emitted_jiffies, recent_enough))
                        break;

                ring = request->ring;
                seqno = request->seqno;
        }
        spin_unlock(&file_priv->mm.lock);

        if (seqno == 0)
                return 0;

        ret = 0;
        if (!i915_seqno_passed(ring->get_seqno(ring), seqno)) {
                /* And wait for the seqno passing without holding any locks and
                 * causing extra latency for others. This is safe as the irq
                 * generation is designed to be run atomically and so is
                 * lockless.
                 */
                ring->user_irq_get(ring);
                ret = wait_event_interruptible(ring->irq_queue,
                                               i915_seqno_passed(ring->get_seqno(ring), seqno)
                                               || atomic_read(&dev_priv->mm.wedged));
                ring->user_irq_put(ring);

                if (ret == 0 && atomic_read(&dev_priv->mm.wedged))
                        ret = -EIO;
        }

        if (ret == 0)
                queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, 0);

        return ret;
}

int
i915_gem_object_pin(struct drm_i915_gem_object *obj,
                    uint32_t alignment,
                    bool map_and_fenceable)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        int ret;

        BUG_ON(obj->pin_count == DRM_I915_GEM_OBJECT_MAX_PIN_COUNT);
        WARN_ON(i915_verify_lists(dev));

        if (obj->gtt_space != NULL) {
                if ((alignment && obj->gtt_offset & (alignment - 1)) ||
                    (map_and_fenceable && !obj->map_and_fenceable)) {
                        WARN(obj->pin_count,
                             "bo is already pinned with incorrect alignment:"
                             " offset=%x, req.alignment=%x, req.map_and_fenceable=%d,"
                             " obj->map_and_fenceable=%d\n",
                             obj->gtt_offset, alignment,
                             map_and_fenceable,
                             obj->map_and_fenceable);
                        ret = i915_gem_object_unbind(obj);
                        if (ret)
                                return ret;
                }
        }

        if (obj->gtt_space == NULL) {
                ret = i915_gem_object_bind_to_gtt(obj, alignment,
                                                  map_and_fenceable);
                if (ret)
                        return ret;
        }

        if (obj->pin_count++ == 0) {
                if (!obj->active)
                        list_move_tail(&obj->mm_list,
                                       &dev_priv->mm.pinned_list);
        }
        obj->pin_mappable |= map_and_fenceable;

        WARN_ON(i915_verify_lists(dev));
        return 0;
}

void
i915_gem_object_unpin(struct drm_i915_gem_object *obj)
{
        struct drm_device *dev = obj->base.dev;
        drm_i915_private_t *dev_priv = dev->dev_private;

        WARN_ON(i915_verify_lists(dev));
        BUG_ON(obj->pin_count == 0);
        BUG_ON(obj->gtt_space == NULL);

        if (--obj->pin_count == 0) {
                if (!obj->active)
                        list_move_tail(&obj->mm_list,
                                       &dev_priv->mm.inactive_list);
                obj->pin_mappable = false;
        }
        WARN_ON(i915_verify_lists(dev));
}

int
i915_gem_pin_ioctl(struct drm_device *dev, void *data,
                   struct drm_file *file)
{
        struct drm_i915_gem_pin *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (obj == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        if (obj->madv != I915_MADV_WILLNEED) {
                DRM_ERROR("Attempting to pin a purgeable buffer\n");
                ret = -EINVAL;
                goto out;
        }

        if (obj->pin_filp != NULL && obj->pin_filp != file) {
                DRM_ERROR("Already pinned in i915_gem_pin_ioctl(): %d\n",
                          args->handle);
                ret = -EINVAL;
                goto out;
        }

        obj->user_pin_count++;
        obj->pin_filp = file;
        if (obj->user_pin_count == 1) {
                ret = i915_gem_object_pin(obj, args->alignment, true);
                if (ret)
                        goto out;
        }

        /* XXX - flush the CPU caches for pinned objects
         * as the X server doesn't manage domains yet
         */
        i915_gem_object_flush_cpu_write_domain(obj);
        args->offset = obj->gtt_offset;
out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

int
i915_gem_unpin_ioctl(struct drm_device *dev, void *data,
                     struct drm_file *file)
{
        struct drm_i915_gem_pin *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (obj == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        if (obj->pin_filp != file) {
                DRM_ERROR("Not pinned by caller in i915_gem_pin_ioctl(): %d\n",
                          args->handle);
                ret = -EINVAL;
                goto out;
        }
        obj->user_pin_count--;
        if (obj->user_pin_count == 0) {
                obj->pin_filp = NULL;
                i915_gem_object_unpin(obj);
        }

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

int
i915_gem_busy_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file)
{
        struct drm_i915_gem_busy *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (obj == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Count all active objects as busy, even if they are currently not used
         * by the gpu. Users of this interface expect objects to eventually
         * become non-busy without any further actions, therefore emit any
         * necessary flushes here.
         */
        args->busy = obj->active;
        if (args->busy) {
                /* Unconditionally flush objects, even when the gpu still uses this
                 * object. Userspace calling this function indicates that it wants to
                 * use this buffer rather sooner than later, so issuing the required
                 * flush earlier is beneficial.
                 */
                if (obj->base.write_domain & I915_GEM_GPU_DOMAINS)
                        i915_gem_flush_ring(dev, obj->ring,
                                            0, obj->base.write_domain);

                /* Update the active list for the hardware's current position.
                 * Otherwise this only updates on a delayed timer or when irqs
                 * are actually unmasked, and our working set ends up being
                 * larger than required.
                 */
                i915_gem_retire_requests_ring(dev, obj->ring);

                args->busy = obj->active;
        }

        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

int
i915_gem_throttle_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file_priv)
{
    return i915_gem_ring_throttle(dev, file_priv);
}

int
i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
                       struct drm_file *file_priv)
{
        struct drm_i915_gem_madvise *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        switch (args->madv) {
        case I915_MADV_DONTNEED:
        case I915_MADV_WILLNEED:
            break;
        default:
            return -EINVAL;
        }

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file_priv, args->handle));
        if (obj == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        if (obj->pin_count) {
                ret = -EINVAL;
                goto out;
        }

        if (obj->madv != __I915_MADV_PURGED)
                obj->madv = args->madv;

        /* if the object is no longer bound, discard its backing storage */
        if (i915_gem_object_is_purgeable(obj) &&
            obj->gtt_space == NULL)
                i915_gem_object_truncate(obj);

        args->retained = obj->madv != __I915_MADV_PURGED;

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

struct drm_i915_gem_object *i915_gem_alloc_object(struct drm_device *dev,
                                                  size_t size)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj;

        obj = kzalloc(sizeof(*obj), GFP_KERNEL);
        if (obj == NULL)
                return NULL;

        if (drm_gem_object_init(dev, &obj->base, size) != 0) {
                kfree(obj);
                return NULL;
        }

        i915_gem_info_add_obj(dev_priv, size);

        obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        obj->base.read_domains = I915_GEM_DOMAIN_CPU;

        obj->agp_type = AGP_USER_MEMORY;
        obj->base.driver_private = NULL;
        obj->fence_reg = I915_FENCE_REG_NONE;
        INIT_LIST_HEAD(&obj->mm_list);
        INIT_LIST_HEAD(&obj->gtt_list);
        INIT_LIST_HEAD(&obj->ring_list);
        INIT_LIST_HEAD(&obj->gpu_write_list);
        obj->madv = I915_MADV_WILLNEED;
        /* Avoid an unnecessary call to unbind on the first bind. */
        obj->map_and_fenceable = true;

        return obj;
}

int i915_gem_init_object(struct drm_gem_object *obj)
{
        BUG();

        return 0;
}

static void i915_gem_free_object_tail(struct drm_i915_gem_object *obj)
{
        struct drm_device *dev = obj->base.dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        int ret;

        ret = i915_gem_object_unbind(obj);
        if (ret == -ERESTARTSYS) {
                list_move(&obj->mm_list,
                          &dev_priv->mm.deferred_free_list);
                return;
        }

        if (obj->base.map_list.map)
                i915_gem_free_mmap_offset(obj);

        drm_gem_object_release(&obj->base);
        i915_gem_info_remove_obj(dev_priv, obj->base.size);

        kfree(obj->page_cpu_valid);
        kfree(obj->bit_17);
        kfree(obj);
}

void i915_gem_free_object(struct drm_gem_object *gem_obj)
{
        struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);
        struct drm_device *dev = obj->base.dev;

        trace_i915_gem_object_destroy(obj);

        while (obj->pin_count > 0)
                i915_gem_object_unpin(obj);

        if (obj->phys_obj)
                i915_gem_detach_phys_object(dev, obj);

        i915_gem_free_object_tail(obj);
}

int
i915_gem_idle(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        int ret;

        mutex_lock(&dev->struct_mutex);

        if (dev_priv->mm.suspended) {
                mutex_unlock(&dev->struct_mutex);
                return 0;
        }

        ret = i915_gpu_idle(dev);
        if (ret) {
                mutex_unlock(&dev->struct_mutex);
                return ret;
        }

        /* Under UMS, be paranoid and evict. */
        if (!drm_core_check_feature(dev, DRIVER_MODESET)) {
                ret = i915_gem_evict_inactive(dev, false);
                if (ret) {
                        mutex_unlock(&dev->struct_mutex);
                        return ret;
                }
        }

        i915_gem_reset_fences(dev);

        /* Hack!  Don't let anybody do execbuf while we don't control the chip.
         * We need to replace this with a semaphore, or something.
         * And not confound mm.suspended!
         */
        dev_priv->mm.suspended = 1;
        del_timer_sync(&dev_priv->hangcheck_timer);

        i915_kernel_lost_context(dev);
        i915_gem_cleanup_ringbuffer(dev);

        mutex_unlock(&dev->struct_mutex);

        /* Cancel the retire work handler, which should be idle now. */
        cancel_delayed_work_sync(&dev_priv->mm.retire_work);

        return 0;
}

int
i915_gem_init_ringbuffer(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        int ret;

        ret = intel_init_render_ring_buffer(dev);
        if (ret)
                return ret;

        if (HAS_BSD(dev)) {
                ret = intel_init_bsd_ring_buffer(dev);
                if (ret)
                        goto cleanup_render_ring;
        }

        if (HAS_BLT(dev)) {
                ret = intel_init_blt_ring_buffer(dev);
                if (ret)
                        goto cleanup_bsd_ring;
        }

        dev_priv->next_seqno = 1;

        return 0;

cleanup_bsd_ring:
        intel_cleanup_ring_buffer(&dev_priv->bsd_ring);
cleanup_render_ring:
        intel_cleanup_ring_buffer(&dev_priv->render_ring);
        return ret;
}

void
i915_gem_cleanup_ringbuffer(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;

        intel_cleanup_ring_buffer(&dev_priv->render_ring);
        intel_cleanup_ring_buffer(&dev_priv->bsd_ring);
        intel_cleanup_ring_buffer(&dev_priv->blt_ring);
}

int
i915_gem_entervt_ioctl(struct drm_device *dev, void *data,
                       struct drm_file *file_priv)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        int ret;

        if (drm_core_check_feature(dev, DRIVER_MODESET))
                return 0;

        if (atomic_read(&dev_priv->mm.wedged)) {
                DRM_ERROR("Reenabling wedged hardware, good luck\n");
                atomic_set(&dev_priv->mm.wedged, 0);
        }

        mutex_lock(&dev->struct_mutex);
        dev_priv->mm.suspended = 0;

        ret = i915_gem_init_ringbuffer(dev);
        if (ret != 0) {
                mutex_unlock(&dev->struct_mutex);
                return ret;
        }

        BUG_ON(!list_empty(&dev_priv->mm.active_list));
        BUG_ON(!list_empty(&dev_priv->render_ring.active_list));
        BUG_ON(!list_empty(&dev_priv->bsd_ring.active_list));
        BUG_ON(!list_empty(&dev_priv->blt_ring.active_list));
        BUG_ON(!list_empty(&dev_priv->mm.flushing_list));
        BUG_ON(!list_empty(&dev_priv->mm.inactive_list));
        BUG_ON(!list_empty(&dev_priv->render_ring.request_list));
        BUG_ON(!list_empty(&dev_priv->bsd_ring.request_list));
        BUG_ON(!list_empty(&dev_priv->blt_ring.request_list));
        mutex_unlock(&dev->struct_mutex);

        ret = drm_irq_install(dev);
        if (ret)
                goto cleanup_ringbuffer;

        return 0;

cleanup_ringbuffer:
        mutex_lock(&dev->struct_mutex);
        i915_gem_cleanup_ringbuffer(dev);
        dev_priv->mm.suspended = 1;
        mutex_unlock(&dev->struct_mutex);

        return ret;
}

int
i915_gem_leavevt_ioctl(struct drm_device *dev, void *data,
                       struct drm_file *file_priv)
{
        if (drm_core_check_feature(dev, DRIVER_MODESET))
                return 0;

        drm_irq_uninstall(dev);
        return i915_gem_idle(dev);
}

void
i915_gem_lastclose(struct drm_device *dev)
{
        int ret;

        if (drm_core_check_feature(dev, DRIVER_MODESET))
                return;

        ret = i915_gem_idle(dev);
        if (ret)
                DRM_ERROR("failed to idle hardware: %d\n", ret);
}

static void
init_ring_lists(struct intel_ring_buffer *ring)
{
        INIT_LIST_HEAD(&ring->active_list);
        INIT_LIST_HEAD(&ring->request_list);
        INIT_LIST_HEAD(&ring->gpu_write_list);
}

void
i915_gem_load(struct drm_device *dev)
{
        int i;
        drm_i915_private_t *dev_priv = dev->dev_private;

        INIT_LIST_HEAD(&dev_priv->mm.active_list);
        INIT_LIST_HEAD(&dev_priv->mm.flushing_list);
        INIT_LIST_HEAD(&dev_priv->mm.inactive_list);
        INIT_LIST_HEAD(&dev_priv->mm.pinned_list);
        INIT_LIST_HEAD(&dev_priv->mm.fence_list);
        INIT_LIST_HEAD(&dev_priv->mm.deferred_free_list);
        INIT_LIST_HEAD(&dev_priv->mm.gtt_list);
        init_ring_lists(&dev_priv->render_ring);
        init_ring_lists(&dev_priv->bsd_ring);
        init_ring_lists(&dev_priv->blt_ring);
        for (i = 0; i < 16; i++)
                INIT_LIST_HEAD(&dev_priv->fence_regs[i].lru_list);
        INIT_DELAYED_WORK(&dev_priv->mm.retire_work,
                          i915_gem_retire_work_handler);
        init_completion(&dev_priv->error_completion);

        /* On GEN3 we really need to make sure the ARB C3 LP bit is set */
        if (IS_GEN3(dev)) {
                u32 tmp = I915_READ(MI_ARB_STATE);
                if (!(tmp & MI_ARB_C3_LP_WRITE_ENABLE)) {
                        /* arb state is a masked write, so set bit + bit in mask */
                        tmp = MI_ARB_C3_LP_WRITE_ENABLE | (MI_ARB_C3_LP_WRITE_ENABLE << MI_ARB_MASK_SHIFT);
                        I915_WRITE(MI_ARB_STATE, tmp);
                }
        }

        /* Old X drivers will take 0-2 for front, back, depth buffers */
        if (!drm_core_check_feature(dev, DRIVER_MODESET))
                dev_priv->fence_reg_start = 3;

        if (INTEL_INFO(dev)->gen >= 4 || IS_I945G(dev) || IS_I945GM(dev) || IS_G33(dev))
                dev_priv->num_fence_regs = 16;
        else
                dev_priv->num_fence_regs = 8;

        /* Initialize fence registers to zero */
        switch (INTEL_INFO(dev)->gen) {
        case 6:
                for (i = 0; i < 16; i++)
                        I915_WRITE64(FENCE_REG_SANDYBRIDGE_0 + (i * 8), 0);
                break;
        case 5:
        case 4:
                for (i = 0; i < 16; i++)
                        I915_WRITE64(FENCE_REG_965_0 + (i * 8), 0);
                break;
        case 3:
                if (IS_I945G(dev) || IS_I945GM(dev) || IS_G33(dev))
                        for (i = 0; i < 8; i++)
                                I915_WRITE(FENCE_REG_945_8 + (i * 4), 0);
        case 2:
                for (i = 0; i < 8; i++)
                        I915_WRITE(FENCE_REG_830_0 + (i * 4), 0);
                break;
        }
        i915_gem_detect_bit_6_swizzle(dev);
        init_waitqueue_head(&dev_priv->pending_flip_queue);

        dev_priv->mm.inactive_shrinker.shrink = i915_gem_inactive_shrink;
        dev_priv->mm.inactive_shrinker.seeks = DEFAULT_SEEKS;
        register_shrinker(&dev_priv->mm.inactive_shrinker);
}

/*
 * Create a physically contiguous memory object for this object
 * e.g. for cursor + overlay regs
 */
static int i915_gem_init_phys_object(struct drm_device *dev,
                                     int id, int size, int align)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_phys_object *phys_obj;
        int ret;

        if (dev_priv->mm.phys_objs[id - 1] || !size)
                return 0;

        phys_obj = kzalloc(sizeof(struct drm_i915_gem_phys_object), GFP_KERNEL);
        if (!phys_obj)
                return -ENOMEM;

        phys_obj->id = id;

        phys_obj->handle = drm_pci_alloc(dev, size, align);
        if (!phys_obj->handle) {
                ret = -ENOMEM;
                goto kfree_obj;
        }
#ifdef CONFIG_X86
        set_memory_wc((unsigned long)phys_obj->handle->vaddr, phys_obj->handle->size / PAGE_SIZE);
#endif

        dev_priv->mm.phys_objs[id - 1] = phys_obj;

        return 0;
kfree_obj:
        kfree(phys_obj);
        return ret;
}

static void i915_gem_free_phys_object(struct drm_device *dev, int id)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_phys_object *phys_obj;

        if (!dev_priv->mm.phys_objs[id - 1])
                return;

        phys_obj = dev_priv->mm.phys_objs[id - 1];
        if (phys_obj->cur_obj) {
                i915_gem_detach_phys_object(dev, phys_obj->cur_obj);
        }

#ifdef CONFIG_X86
        set_memory_wb((unsigned long)phys_obj->handle->vaddr, phys_obj->handle->size / PAGE_SIZE);
#endif
        drm_pci_free(dev, phys_obj->handle);
        kfree(phys_obj);
        dev_priv->mm.phys_objs[id - 1] = NULL;
}

void i915_gem_free_all_phys_object(struct drm_device *dev)
{
        int i;

        for (i = I915_GEM_PHYS_CURSOR_0; i <= I915_MAX_PHYS_OBJECT; i++)
                i915_gem_free_phys_object(dev, i);
}

void i915_gem_detach_phys_object(struct drm_device *dev,
                                 struct drm_i915_gem_object *obj)
{
        struct address_space *mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
        char *vaddr;
        int i;
        int page_count;

        if (!obj->phys_obj)
                return;
        vaddr = obj->phys_obj->handle->vaddr;

        page_count = obj->base.size / PAGE_SIZE;
        for (i = 0; i < page_count; i++) {
                struct page *page = read_cache_page_gfp(mapping, i,
                                                        GFP_HIGHUSER | __GFP_RECLAIMABLE);
                if (!IS_ERR(page)) {
                        char *dst = kmap_atomic(page);
                        memcpy(dst, vaddr + i*PAGE_SIZE, PAGE_SIZE);
                        kunmap_atomic(dst);

                        drm_clflush_pages(&page, 1);

                        set_page_dirty(page);
                        mark_page_accessed(page);
                        page_cache_release(page);
                }
        }
        intel_gtt_chipset_flush();

        obj->phys_obj->cur_obj = NULL;
        obj->phys_obj = NULL;
}

int
i915_gem_attach_phys_object(struct drm_device *dev,
                            struct drm_i915_gem_object *obj,
                            int id,
                            int align)
{
        struct address_space *mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
        drm_i915_private_t *dev_priv = dev->dev_private;
        int ret = 0;
        int page_count;
        int i;

        if (id > I915_MAX_PHYS_OBJECT)
                return -EINVAL;

        if (obj->phys_obj) {
                if (obj->phys_obj->id == id)
                        return 0;
                i915_gem_detach_phys_object(dev, obj);
        }

        /* create a new object */
        if (!dev_priv->mm.phys_objs[id - 1]) {
                ret = i915_gem_init_phys_object(dev, id,
                                                obj->base.size, align);
                if (ret) {
                        DRM_ERROR("failed to init phys object %d size: %zu\n",
                                  id, obj->base.size);
                        return ret;
                }
        }

        /* bind to the object */
        obj->phys_obj = dev_priv->mm.phys_objs[id - 1];
        obj->phys_obj->cur_obj = obj;

        page_count = obj->base.size / PAGE_SIZE;

        for (i = 0; i < page_count; i++) {
                struct page *page;
                char *dst, *src;

                page = read_cache_page_gfp(mapping, i,
                                           GFP_HIGHUSER | __GFP_RECLAIMABLE);
                if (IS_ERR(page))
                        return PTR_ERR(page);

                src = kmap_atomic(page);
                dst = obj->phys_obj->handle->vaddr + (i * PAGE_SIZE);
                memcpy(dst, src, PAGE_SIZE);
                kunmap_atomic(src);

                mark_page_accessed(page);
                page_cache_release(page);
        }

        return 0;
}

static int
i915_gem_phys_pwrite(struct drm_device *dev,
                     struct drm_i915_gem_object *obj,
                     struct drm_i915_gem_pwrite *args,
                     struct drm_file *file_priv)
{
        void *vaddr = obj->phys_obj->handle->vaddr + args->offset;
        char __user *user_data = (char __user *) (uintptr_t) args->data_ptr;

        if (__copy_from_user_inatomic_nocache(vaddr, user_data, args->size)) {
                unsigned long unwritten;

                /* The physical object once assigned is fixed for the lifetime
                 * of the obj, so we can safely drop the lock and continue
                 * to access vaddr.
                 */
                mutex_unlock(&dev->struct_mutex);
                unwritten = copy_from_user(vaddr, user_data, args->size);
                mutex_lock(&dev->struct_mutex);
                if (unwritten)
                        return -EFAULT;
        }

        intel_gtt_chipset_flush();
        return 0;
}

void i915_gem_release(struct drm_device *dev, struct drm_file *file)
{
        struct drm_i915_file_private *file_priv = file->driver_priv;

        /* Clean up our request list when the client is going away, so that
         * later retire_requests won't dereference our soon-to-be-gone
         * file_priv.
         */
        spin_lock(&file_priv->mm.lock);
        while (!list_empty(&file_priv->mm.request_list)) {
                struct drm_i915_gem_request *request;

                request = list_first_entry(&file_priv->mm.request_list,
                                           struct drm_i915_gem_request,
                                           client_list);
                list_del(&request->client_list);
                request->file_priv = NULL;
        }
        spin_unlock(&file_priv->mm.lock);
}

static int
i915_gpu_is_active(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        int lists_empty;

        lists_empty = list_empty(&dev_priv->mm.flushing_list) &&
                      list_empty(&dev_priv->mm.active_list);

        return !lists_empty;
}

static int
i915_gem_inactive_shrink(struct shrinker *shrinker,
                         int nr_to_scan,
                         gfp_t gfp_mask)
{
        struct drm_i915_private *dev_priv =
                container_of(shrinker,
                             struct drm_i915_private,
                             mm.inactive_shrinker);
        struct drm_device *dev = dev_priv->dev;
        struct drm_i915_gem_object *obj, *next;
        int cnt;

        if (!mutex_trylock(&dev->struct_mutex))
                return 0;

        /* "fast-path" to count number of available objects */
        if (nr_to_scan == 0) {
                cnt = 0;
                list_for_each_entry(obj,
                                    &dev_priv->mm.inactive_list,
                                    mm_list)
                        cnt++;
                mutex_unlock(&dev->struct_mutex);
                return cnt / 100 * sysctl_vfs_cache_pressure;
        }

rescan:
        /* first scan for clean buffers */
        i915_gem_retire_requests(dev);

        list_for_each_entry_safe(obj, next,
                                 &dev_priv->mm.inactive_list,
                                 mm_list) {
                if (i915_gem_object_is_purgeable(obj)) {
                        if (i915_gem_object_unbind(obj) == 0 &&
                            --nr_to_scan == 0)
                                break;
                }
        }

        /* second pass, evict/count anything still on the inactive list */
        cnt = 0;
        list_for_each_entry_safe(obj, next,
                                 &dev_priv->mm.inactive_list,
                                 mm_list) {
                if (nr_to_scan &&
                    i915_gem_object_unbind(obj) == 0)
                        nr_to_scan--;
                else
                        cnt++;
        }

        if (nr_to_scan && i915_gpu_is_active(dev)) {
                /*
                 * We are desperate for pages, so as a last resort, wait
                 * for the GPU to finish and discard whatever we can.
                 * This has a dramatic impact to reduce the number of
                 * OOM-killer events whilst running the GPU aggressively.
                 */
                if (i915_gpu_idle(dev) == 0)
                        goto rescan;
        }
        mutex_unlock(&dev->struct_mutex);
        return cnt / 100 * sysctl_vfs_cache_pressure;
}