[mirror_ubuntu-artful-kernel.git] / drivers / gpu / drm / i915 / i915_gem_execbuffer.c

/*
 * Copyright © 2008,2010 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>
 *    Chris Wilson <chris@chris-wilson.co.uk>
 *
 */

#include "drmP.h"
#include "drm.h"
#include "i915_drm.h"
#include "i915_drv.h"
#include "i915_trace.h"
#include "intel_drv.h"

struct change_domains {
        uint32_t invalidate_domains;
        uint32_t flush_domains;
        uint32_t flush_rings;
};

/*
 * Set the next domain for the specified object. This
 * may not actually perform the necessary flushing/invaliding though,
 * as that may want to be batched with other set_domain operations
 *
 * This is (we hope) the only really tricky part of gem. The goal
 * is fairly simple -- track which caches hold bits of the object
 * and make sure they remain coherent. A few concrete examples may
 * help to explain how it works. For shorthand, we use the notation
 * (read_domains, write_domain), e.g. (CPU, CPU) to indicate the
 * a pair of read and write domain masks.
 *
 * Case 1: the batch buffer
 *
 *      1. Allocated
 *      2. Written by CPU
 *      3. Mapped to GTT
 *      4. Read by GPU
 *      5. Unmapped from GTT
 *      6. Freed
 *
 *      Let's take these a step at a time
 *
 *      1. Allocated
 *              Pages allocated from the kernel may still have
 *              cache contents, so we set them to (CPU, CPU) always.
 *      2. Written by CPU (using pwrite)
 *              The pwrite function calls set_domain (CPU, CPU) and
 *              this function does nothing (as nothing changes)
 *      3. Mapped by GTT
 *              This function asserts that the object is not
 *              currently in any GPU-based read or write domains
 *      4. Read by GPU
 *              i915_gem_execbuffer calls set_domain (COMMAND, 0).
 *              As write_domain is zero, this function adds in the
 *              current read domains (CPU+COMMAND, 0).
 *              flush_domains is set to CPU.
 *              invalidate_domains is set to COMMAND
 *              clflush is run to get data out of the CPU caches
 *              then i915_dev_set_domain calls i915_gem_flush to
 *              emit an MI_FLUSH and drm_agp_chipset_flush
 *      5. Unmapped from GTT
 *              i915_gem_object_unbind calls set_domain (CPU, CPU)
 *              flush_domains and invalidate_domains end up both zero
 *              so no flushing/invalidating happens
 *      6. Freed
 *              yay, done
 *
 * Case 2: The shared render buffer
 *
 *      1. Allocated
 *      2. Mapped to GTT
 *      3. Read/written by GPU
 *      4. set_domain to (CPU,CPU)
 *      5. Read/written by CPU
 *      6. Read/written by GPU
 *
 *      1. Allocated
 *              Same as last example, (CPU, CPU)
 *      2. Mapped to GTT
 *              Nothing changes (assertions find that it is not in the GPU)
 *      3. Read/written by GPU
 *              execbuffer calls set_domain (RENDER, RENDER)
 *              flush_domains gets CPU
 *              invalidate_domains gets GPU
 *              clflush (obj)
 *              MI_FLUSH and drm_agp_chipset_flush
 *      4. set_domain (CPU, CPU)
 *              flush_domains gets GPU
 *              invalidate_domains gets CPU
 *              wait_rendering (obj) to make sure all drawing is complete.
 *              This will include an MI_FLUSH to get the data from GPU
 *              to memory
 *              clflush (obj) to invalidate the CPU cache
 *              Another MI_FLUSH in i915_gem_flush (eliminate this somehow?)
 *      5. Read/written by CPU
 *              cache lines are loaded and dirtied
 *      6. Read written by GPU
 *              Same as last GPU access
 *
 * Case 3: The constant buffer
 *
 *      1. Allocated
 *      2. Written by CPU
 *      3. Read by GPU
 *      4. Updated (written) by CPU again
 *      5. Read by GPU
 *
 *      1. Allocated
 *              (CPU, CPU)
 *      2. Written by CPU
 *              (CPU, CPU)
 *      3. Read by GPU
 *              (CPU+RENDER, 0)
 *              flush_domains = CPU
 *              invalidate_domains = RENDER
 *              clflush (obj)
 *              MI_FLUSH
 *              drm_agp_chipset_flush
 *      4. Updated (written) by CPU again
 *              (CPU, CPU)
 *              flush_domains = 0 (no previous write domain)
 *              invalidate_domains = 0 (no new read domains)
 *      5. Read by GPU
 *              (CPU+RENDER, 0)
 *              flush_domains = CPU
 *              invalidate_domains = RENDER
 *              clflush (obj)
 *              MI_FLUSH
 *              drm_agp_chipset_flush
 */
static void
i915_gem_object_set_to_gpu_domain(struct drm_i915_gem_object *obj,
                                  struct intel_ring_buffer *ring,
                                  struct change_domains *cd)
{
        uint32_t invalidate_domains = 0, flush_domains = 0;

        /*
         * If the object isn't moving to a new write domain,
         * let the object stay in multiple read domains
         */
        if (obj->base.pending_write_domain == 0)
                obj->base.pending_read_domains |= obj->base.read_domains;

        /*
         * Flush the current write domain if
         * the new read domains don't match. Invalidate
         * any read domains which differ from the old
         * write domain
         */
        if (obj->base.write_domain &&
            (((obj->base.write_domain != obj->base.pending_read_domains ||
               obj->ring != ring)) ||
             (obj->fenced_gpu_access && !obj->pending_fenced_gpu_access))) {
                flush_domains |= obj->base.write_domain;
                invalidate_domains |=
                        obj->base.pending_read_domains & ~obj->base.write_domain;
        }
        /*
         * Invalidate any read caches which may have
         * stale data. That is, any new read domains.
         */
        invalidate_domains |= obj->base.pending_read_domains & ~obj->base.read_domains;
        if ((flush_domains | invalidate_domains) & I915_GEM_DOMAIN_CPU)
                i915_gem_clflush_object(obj);

        /* blow away mappings if mapped through GTT */
        if ((flush_domains | invalidate_domains) & I915_GEM_DOMAIN_GTT)
                i915_gem_release_mmap(obj);

        /* The actual obj->write_domain will be updated with
         * pending_write_domain after we emit the accumulated flush for all
         * of our domain changes in execbuffers (which clears objects'
         * write_domains).  So if we have a current write domain that we
         * aren't changing, set pending_write_domain to that.
         */
        if (flush_domains == 0 && obj->base.pending_write_domain == 0)
                obj->base.pending_write_domain = obj->base.write_domain;

        cd->invalidate_domains |= invalidate_domains;
        cd->flush_domains |= flush_domains;
        if (flush_domains & I915_GEM_GPU_DOMAINS)
                cd->flush_rings |= obj->ring->id;
        if (invalidate_domains & I915_GEM_GPU_DOMAINS)
                cd->flush_rings |= ring->id;
}

struct eb_objects {
        int and;
        struct hlist_head buckets[0];
};

static struct eb_objects *
eb_create(int size)
{
        struct eb_objects *eb;
        int count = PAGE_SIZE / sizeof(struct hlist_head) / 2;
        while (count > size)
                count >>= 1;
        eb = kzalloc(count*sizeof(struct hlist_head) +
                     sizeof(struct eb_objects),
                     GFP_KERNEL);
        if (eb == NULL)
                return eb;

        eb->and = count - 1;
        return eb;
}

static void
eb_reset(struct eb_objects *eb)
{
        memset(eb->buckets, 0, (eb->and+1)*sizeof(struct hlist_head));
}

static void
eb_add_object(struct eb_objects *eb, struct drm_i915_gem_object *obj)
{
        hlist_add_head(&obj->exec_node,
                       &eb->buckets[obj->exec_handle & eb->and]);
}

static struct drm_i915_gem_object *
eb_get_object(struct eb_objects *eb, unsigned long handle)
{
        struct hlist_head *head;
        struct hlist_node *node;
        struct drm_i915_gem_object *obj;

        head = &eb->buckets[handle & eb->and];
        hlist_for_each(node, head) {
                obj = hlist_entry(node, struct drm_i915_gem_object, exec_node);
                if (obj->exec_handle == handle)
                        return obj;
        }

        return NULL;
}

static void
eb_destroy(struct eb_objects *eb)
{
        kfree(eb);
}

static int
i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
                                   struct eb_objects *eb,
                                   struct drm_i915_gem_relocation_entry *reloc)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_gem_object *target_obj;
        uint32_t target_offset;
        int ret = -EINVAL;

        /* we've already hold a reference to all valid objects */
        target_obj = &eb_get_object(eb, reloc->target_handle)->base;
        if (unlikely(target_obj == NULL))
                return -ENOENT;

        target_offset = to_intel_bo(target_obj)->gtt_offset;

        /* The target buffer should have appeared before us in the
         * exec_object list, so it should have a GTT space bound by now.
         */
        if (unlikely(target_offset == 0)) {
                DRM_ERROR("No GTT space found for object %d\n",
                          reloc->target_handle);
                return ret;
        }

        /* Validate that the target is in a valid r/w GPU domain */
        if (unlikely(reloc->write_domain & (reloc->write_domain - 1))) {
                DRM_ERROR("reloc with multiple write domains: "
                          "obj %p target %d offset %d "
                          "read %08x write %08x",
                          obj, reloc->target_handle,
                          (int) reloc->offset,
                          reloc->read_domains,
                          reloc->write_domain);
                return ret;
        }
        if (unlikely((reloc->write_domain | reloc->read_domains) & I915_GEM_DOMAIN_CPU)) {
                DRM_ERROR("reloc with read/write CPU domains: "
                          "obj %p target %d offset %d "
                          "read %08x write %08x",
                          obj, reloc->target_handle,
                          (int) reloc->offset,
                          reloc->read_domains,
                          reloc->write_domain);
                return ret;
        }
        if (unlikely(reloc->write_domain && target_obj->pending_write_domain &&
                     reloc->write_domain != target_obj->pending_write_domain)) {
                DRM_ERROR("Write domain conflict: "
                          "obj %p target %d offset %d "
                          "new %08x old %08x\n",
                          obj, reloc->target_handle,
                          (int) reloc->offset,
                          reloc->write_domain,
                          target_obj->pending_write_domain);
                return ret;
        }

        target_obj->pending_read_domains |= reloc->read_domains;
        target_obj->pending_write_domain |= reloc->write_domain;

        /* If the relocation already has the right value in it, no
         * more work needs to be done.
         */
        if (target_offset == reloc->presumed_offset)
                return 0;

        /* Check that the relocation address is valid... */
        if (unlikely(reloc->offset > obj->base.size - 4)) {
                DRM_ERROR("Relocation beyond object bounds: "
                          "obj %p target %d offset %d size %d.\n",
                          obj, reloc->target_handle,
                          (int) reloc->offset,
                          (int) obj->base.size);
                return ret;
        }
        if (unlikely(reloc->offset & 3)) {
                DRM_ERROR("Relocation not 4-byte aligned: "
                          "obj %p target %d offset %d.\n",
                          obj, reloc->target_handle,
                          (int) reloc->offset);
                return ret;
        }

        /* and points to somewhere within the target object. */
        if (unlikely(reloc->delta >= target_obj->size)) {
                DRM_ERROR("Relocation beyond target object bounds: "
                          "obj %p target %d delta %d size %d.\n",
                          obj, reloc->target_handle,
                          (int) reloc->delta,
                          (int) target_obj->size);
                return ret;
        }

        reloc->delta += target_offset;
        if (obj->base.write_domain == I915_GEM_DOMAIN_CPU) {
                uint32_t page_offset = reloc->offset & ~PAGE_MASK;
                char *vaddr;

                vaddr = kmap_atomic(obj->pages[reloc->offset >> PAGE_SHIFT]);
                *(uint32_t *)(vaddr + page_offset) = reloc->delta;
                kunmap_atomic(vaddr);
        } else {
                struct drm_i915_private *dev_priv = dev->dev_private;
                uint32_t __iomem *reloc_entry;
                void __iomem *reloc_page;

                ret = i915_gem_object_set_to_gtt_domain(obj, 1);
                if (ret)
                        return ret;

                /* Map the page containing the relocation we're going to perform.  */
                reloc->offset += obj->gtt_offset;
                reloc_page = io_mapping_map_atomic_wc(dev_priv->mm.gtt_mapping,
                                                      reloc->offset & PAGE_MASK);
                reloc_entry = (uint32_t __iomem *)
                        (reloc_page + (reloc->offset & ~PAGE_MASK));
                iowrite32(reloc->delta, reloc_entry);
                io_mapping_unmap_atomic(reloc_page);
        }

        /* and update the user's relocation entry */
        reloc->presumed_offset = target_offset;

        return 0;
}

static int
i915_gem_execbuffer_relocate_object(struct drm_i915_gem_object *obj,
                                    struct eb_objects *eb)
{
        struct drm_i915_gem_relocation_entry __user *user_relocs;
        struct drm_i915_gem_exec_object2 *entry = obj->exec_entry;
        int i, ret;

        user_relocs = (void __user *)(uintptr_t)entry->relocs_ptr;
        for (i = 0; i < entry->relocation_count; i++) {
                struct drm_i915_gem_relocation_entry reloc;

                if (__copy_from_user_inatomic(&reloc,
                                              user_relocs+i,
                                              sizeof(reloc)))
                        return -EFAULT;

                ret = i915_gem_execbuffer_relocate_entry(obj, eb, &reloc);
                if (ret)
                        return ret;

                if (__copy_to_user_inatomic(&user_relocs[i].presumed_offset,
                                            &reloc.presumed_offset,
                                            sizeof(reloc.presumed_offset)))
                        return -EFAULT;
        }

        return 0;
}

static int
i915_gem_execbuffer_relocate_object_slow(struct drm_i915_gem_object *obj,
                                         struct eb_objects *eb,
                                         struct drm_i915_gem_relocation_entry *relocs)
{
        const struct drm_i915_gem_exec_object2 *entry = obj->exec_entry;
        int i, ret;

        for (i = 0; i < entry->relocation_count; i++) {
                ret = i915_gem_execbuffer_relocate_entry(obj, eb, &relocs[i]);
                if (ret)
                        return ret;
        }

        return 0;
}

static int
i915_gem_execbuffer_relocate(struct drm_device *dev,
                             struct eb_objects *eb,
                             struct list_head *objects)
{
        struct drm_i915_gem_object *obj;
        int ret;

        list_for_each_entry(obj, objects, exec_list) {
                ret = i915_gem_execbuffer_relocate_object(obj, eb);
                if (ret)
                        return ret;
        }

        return 0;
}

static int
i915_gem_execbuffer_reserve(struct intel_ring_buffer *ring,
                            struct drm_file *file,
                            struct list_head *objects)
{
        struct drm_i915_gem_object *obj;
        int ret, retry;
        bool has_fenced_gpu_access = INTEL_INFO(ring->dev)->gen < 4;
        struct list_head ordered_objects;

        INIT_LIST_HEAD(&ordered_objects);
        while (!list_empty(objects)) {
                struct drm_i915_gem_exec_object2 *entry;
                bool need_fence, need_mappable;

                obj = list_first_entry(objects,
                                       struct drm_i915_gem_object,
                                       exec_list);
                entry = obj->exec_entry;

                need_fence =
                        has_fenced_gpu_access &&
                        entry->flags & EXEC_OBJECT_NEEDS_FENCE &&
                        obj->tiling_mode != I915_TILING_NONE;
                need_mappable =
                        entry->relocation_count ? true : need_fence;

                if (need_mappable)
                        list_move(&obj->exec_list, &ordered_objects);
                else
                        list_move_tail(&obj->exec_list, &ordered_objects);

                obj->base.pending_read_domains = 0;
                obj->base.pending_write_domain = 0;
        }
        list_splice(&ordered_objects, objects);

        /* Attempt to pin all of the buffers into the GTT.
         * This is done in 3 phases:
         *
         * 1a. Unbind all objects that do not match the GTT constraints for
         *     the execbuffer (fenceable, mappable, alignment etc).
         * 1b. Increment pin count for already bound objects.
         * 2.  Bind new objects.
         * 3.  Decrement pin count.
         *
         * This avoid unnecessary unbinding of later objects in order to makr
         * room for the earlier objects *unless* we need to defragment.
         */
        retry = 0;
        do {
                ret = 0;

                /* Unbind any ill-fitting objects or pin. */
                list_for_each_entry(obj, objects, exec_list) {
                        struct drm_i915_gem_exec_object2 *entry = obj->exec_entry;
                        bool need_fence, need_mappable;
                        if (!obj->gtt_space)
                                continue;

                        need_fence =
                                has_fenced_gpu_access &&
                                entry->flags & EXEC_OBJECT_NEEDS_FENCE &&
                                obj->tiling_mode != I915_TILING_NONE;
                        need_mappable =
                                entry->relocation_count ? true : need_fence;

                        if ((entry->alignment && obj->gtt_offset & (entry->alignment - 1)) ||
                            (need_mappable && !obj->map_and_fenceable))
                                ret = i915_gem_object_unbind(obj);
                        else
                                ret = i915_gem_object_pin(obj,
                                                          entry->alignment,
                                                          need_mappable);
                        if (ret)
                                goto err;

                        entry++;
                }

                /* Bind fresh objects */
                list_for_each_entry(obj, objects, exec_list) {
                        struct drm_i915_gem_exec_object2 *entry = obj->exec_entry;
                        bool need_fence;

                        need_fence =
                                has_fenced_gpu_access &&
                                entry->flags & EXEC_OBJECT_NEEDS_FENCE &&
                                obj->tiling_mode != I915_TILING_NONE;

                        if (!obj->gtt_space) {
                                bool need_mappable =
                                        entry->relocation_count ? true : need_fence;

                                ret = i915_gem_object_pin(obj,
                                                          entry->alignment,
                                                          need_mappable);
                                if (ret)
                                        break;
                        }

                        if (has_fenced_gpu_access) {
                                if (need_fence) {
                                        ret = i915_gem_object_get_fence(obj, ring, 1);
                                        if (ret)
                                                break;
                                } else if (entry->flags & EXEC_OBJECT_NEEDS_FENCE &&
                                           obj->tiling_mode == I915_TILING_NONE) {
                                        /* XXX pipelined! */
                                        ret = i915_gem_object_put_fence(obj);
                                        if (ret)
                                                break;
                                }
                                obj->pending_fenced_gpu_access = need_fence;
                        }

                        entry->offset = obj->gtt_offset;
                }

                /* Decrement pin count for bound objects */
                list_for_each_entry(obj, objects, exec_list) {
                        if (obj->gtt_space)
                                i915_gem_object_unpin(obj);
                }

                if (ret != -ENOSPC || retry > 1)
                        return ret;

                /* First attempt, just clear anything that is purgeable.
                 * Second attempt, clear the entire GTT.
                 */
                ret = i915_gem_evict_everything(ring->dev, retry == 0);
                if (ret)
                        return ret;

                retry++;
        } while (1);

err:
        obj = list_entry(obj->exec_list.prev,
                         struct drm_i915_gem_object,
                         exec_list);
        while (objects != &obj->exec_list) {
                if (obj->gtt_space)
                        i915_gem_object_unpin(obj);

                obj = list_entry(obj->exec_list.prev,
                                 struct drm_i915_gem_object,
                                 exec_list);
        }

        return ret;
}

static int
i915_gem_execbuffer_relocate_slow(struct drm_device *dev,
                                  struct drm_file *file,
                                  struct intel_ring_buffer *ring,
                                  struct list_head *objects,
                                  struct eb_objects *eb,
                                  struct drm_i915_gem_exec_object2 *exec,
                                  int count)
{
        struct drm_i915_gem_relocation_entry *reloc;
        struct drm_i915_gem_object *obj;
        int *reloc_offset;
        int i, total, ret;

        /* We may process another execbuffer during the unlock... */
        while (!list_empty(objects)) {
                obj = list_first_entry(objects,
                                       struct drm_i915_gem_object,
                                       exec_list);
                list_del_init(&obj->exec_list);
                drm_gem_object_unreference(&obj->base);
        }

        mutex_unlock(&dev->struct_mutex);

        total = 0;
        for (i = 0; i < count; i++)
                total += exec[i].relocation_count;

        reloc_offset = drm_malloc_ab(count, sizeof(*reloc_offset));
        reloc = drm_malloc_ab(total, sizeof(*reloc));
        if (reloc == NULL || reloc_offset == NULL) {
                drm_free_large(reloc);
                drm_free_large(reloc_offset);
                mutex_lock(&dev->struct_mutex);
                return -ENOMEM;
        }

        total = 0;
        for (i = 0; i < count; i++) {
                struct drm_i915_gem_relocation_entry __user *user_relocs;

                user_relocs = (void __user *)(uintptr_t)exec[i].relocs_ptr;

                if (copy_from_user(reloc+total, user_relocs,
                                   exec[i].relocation_count * sizeof(*reloc))) {
                        ret = -EFAULT;
                        mutex_lock(&dev->struct_mutex);
                        goto err;
                }

                reloc_offset[i] = total;
                total += exec[i].relocation_count;
        }

        ret = i915_mutex_lock_interruptible(dev);
        if (ret) {
                mutex_lock(&dev->struct_mutex);
                goto err;
        }

        /* reacquire the objects */
        eb_reset(eb);
        for (i = 0; i < count; i++) {
                obj = to_intel_bo(drm_gem_object_lookup(dev, file,
                                                        exec[i].handle));
                if (obj == NULL) {
                        DRM_ERROR("Invalid object handle %d at index %d\n",
                                   exec[i].handle, i);
                        ret = -ENOENT;
                        goto err;
                }

                list_add_tail(&obj->exec_list, objects);
                obj->exec_handle = exec[i].handle;
                obj->exec_entry = &exec[i];
                eb_add_object(eb, obj);
        }

        ret = i915_gem_execbuffer_reserve(ring, file, objects);
        if (ret)
                goto err;

        list_for_each_entry(obj, objects, exec_list) {
                int offset = obj->exec_entry - exec;
                ret = i915_gem_execbuffer_relocate_object_slow(obj, eb,
                                                               reloc + reloc_offset[offset]);
                if (ret)
                        goto err;
        }

        /* Leave the user relocations as are, this is the painfully slow path,
         * and we want to avoid the complication of dropping the lock whilst
         * having buffers reserved in the aperture and so causing spurious
         * ENOSPC for random operations.
         */

err:
        drm_free_large(reloc);
        drm_free_large(reloc_offset);
        return ret;
}

static int
i915_gem_execbuffer_flush(struct drm_device *dev,
                          uint32_t invalidate_domains,
                          uint32_t flush_domains,
                          uint32_t flush_rings)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        int i, ret;

        if (flush_domains & I915_GEM_DOMAIN_CPU)
                intel_gtt_chipset_flush();

        if (flush_domains & I915_GEM_DOMAIN_GTT)
                wmb();

        if ((flush_domains | invalidate_domains) & I915_GEM_GPU_DOMAINS) {
                for (i = 0; i < I915_NUM_RINGS; i++)
                        if (flush_rings & (1 << i)) {
                                ret = i915_gem_flush_ring(&dev_priv->ring[i],
                                                          invalidate_domains,
                                                          flush_domains);
                                if (ret)
                                        return ret;
                        }
        }

        return 0;
}

static int
i915_gem_execbuffer_sync_rings(struct drm_i915_gem_object *obj,
                               struct intel_ring_buffer *to)
{
        struct intel_ring_buffer *from = obj->ring;
        u32 seqno;
        int ret, idx;

        if (from == NULL || to == from)
                return 0;

        /* XXX gpu semaphores are currently causing hard hangs on SNB mobile */
        if (INTEL_INFO(obj->base.dev)->gen < 6 || IS_MOBILE(obj->base.dev))
                return i915_gem_object_wait_rendering(obj, true);

        idx = intel_ring_sync_index(from, to);

        seqno = obj->last_rendering_seqno;
        if (seqno <= from->sync_seqno[idx])
                return 0;

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

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

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

                seqno = request->seqno;
        }

        from->sync_seqno[idx] = seqno;
        return intel_ring_sync(to, from, seqno - 1);
}

static int
i915_gem_execbuffer_move_to_gpu(struct intel_ring_buffer *ring,
                                struct list_head *objects)
{
        struct drm_i915_gem_object *obj;
        struct change_domains cd;
        int ret;

        cd.invalidate_domains = 0;
        cd.flush_domains = 0;
        cd.flush_rings = 0;
        list_for_each_entry(obj, objects, exec_list)
                i915_gem_object_set_to_gpu_domain(obj, ring, &cd);

        if (cd.invalidate_domains | cd.flush_domains) {
                ret = i915_gem_execbuffer_flush(ring->dev,
                                                cd.invalidate_domains,
                                                cd.flush_domains,
                                                cd.flush_rings);
                if (ret)
                        return ret;
        }

        list_for_each_entry(obj, objects, exec_list) {
                ret = i915_gem_execbuffer_sync_rings(obj, ring);
                if (ret)
                        return ret;
        }

        return 0;
}

static bool
i915_gem_check_execbuffer(struct drm_i915_gem_execbuffer2 *exec)
{
        return ((exec->batch_start_offset | exec->batch_len) & 0x7) == 0;
}

static int
validate_exec_list(struct drm_i915_gem_exec_object2 *exec,
                   int count)
{
        int i;

        for (i = 0; i < count; i++) {
                char __user *ptr = (char __user *)(uintptr_t)exec[i].relocs_ptr;
                int length; /* limited by fault_in_pages_readable() */

                /* First check for malicious input causing overflow */
                if (exec[i].relocation_count >
                    INT_MAX / sizeof(struct drm_i915_gem_relocation_entry))
                        return -EINVAL;

                length = exec[i].relocation_count *
                        sizeof(struct drm_i915_gem_relocation_entry);
                if (!access_ok(VERIFY_READ, ptr, length))
                        return -EFAULT;

                /* we may also need to update the presumed offsets */
                if (!access_ok(VERIFY_WRITE, ptr, length))
                        return -EFAULT;

                if (fault_in_pages_readable(ptr, length))
                        return -EFAULT;
        }

        return 0;
}

static int
i915_gem_execbuffer_wait_for_flips(struct intel_ring_buffer *ring,
                                   struct list_head *objects)
{
        struct drm_i915_gem_object *obj;
        int flips;

        /* Check for any pending flips. As we only maintain a flip queue depth
         * of 1, we can simply insert a WAIT for the next display flip prior
         * to executing the batch and avoid stalling the CPU.
         */
        flips = 0;
        list_for_each_entry(obj, objects, exec_list) {
                if (obj->base.write_domain)
                        flips |= atomic_read(&obj->pending_flip);
        }
        if (flips) {
                int plane, flip_mask, ret;

                for (plane = 0; flips >> plane; plane++) {
                        if (((flips >> plane) & 1) == 0)
                                continue;

                        if (plane)
                                flip_mask = MI_WAIT_FOR_PLANE_B_FLIP;
                        else
                                flip_mask = MI_WAIT_FOR_PLANE_A_FLIP;

                        ret = intel_ring_begin(ring, 2);
                        if (ret)
                                return ret;

                        intel_ring_emit(ring, MI_WAIT_FOR_EVENT | flip_mask);
                        intel_ring_emit(ring, MI_NOOP);
                        intel_ring_advance(ring);
                }
        }

        return 0;
}

static void
i915_gem_execbuffer_move_to_active(struct list_head *objects,
                                   struct intel_ring_buffer *ring,
                                   u32 seqno)
{
        struct drm_i915_gem_object *obj;

        list_for_each_entry(obj, objects, exec_list) {
                  u32 old_read = obj->base.read_domains;
                  u32 old_write = obj->base.write_domain;


                obj->base.read_domains = obj->base.pending_read_domains;
                obj->base.write_domain = obj->base.pending_write_domain;
                obj->fenced_gpu_access = obj->pending_fenced_gpu_access;

                i915_gem_object_move_to_active(obj, ring, seqno);
                if (obj->base.write_domain) {
                        obj->dirty = 1;
                        obj->pending_gpu_write = true;
                        list_move_tail(&obj->gpu_write_list,
                                       &ring->gpu_write_list);
                        intel_mark_busy(ring->dev, obj);
                }

                trace_i915_gem_object_change_domain(obj, old_read, old_write);
        }
}

static void
i915_gem_execbuffer_retire_commands(struct drm_device *dev,
                                    struct drm_file *file,
                                    struct intel_ring_buffer *ring)
{
        struct drm_i915_gem_request *request;
        u32 invalidate;

        /*
         * Ensure that the commands in the batch buffer are
         * finished before the interrupt fires.
         *
         * The sampler always gets flushed on i965 (sigh).
         */
        invalidate = I915_GEM_DOMAIN_COMMAND;
        if (INTEL_INFO(dev)->gen >= 4)
                invalidate |= I915_GEM_DOMAIN_SAMPLER;
        if (ring->flush(ring, invalidate, 0)) {
                i915_gem_next_request_seqno(ring);
                return;
        }

        /* Add a breadcrumb for the completion of the batch buffer */
        request = kzalloc(sizeof(*request), GFP_KERNEL);
        if (request == NULL || i915_add_request(ring, file, request)) {
                i915_gem_next_request_seqno(ring);
                kfree(request);
        }
}

static int
i915_gem_do_execbuffer(struct drm_device *dev, void *data,
                       struct drm_file *file,
                       struct drm_i915_gem_execbuffer2 *args,
                       struct drm_i915_gem_exec_object2 *exec)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct list_head objects;
        struct eb_objects *eb;
        struct drm_i915_gem_object *batch_obj;
        struct drm_clip_rect *cliprects = NULL;
        struct intel_ring_buffer *ring;
        u32 exec_start, exec_len;
        u32 seqno;
        int ret, mode, i;

        if (!i915_gem_check_execbuffer(args)) {
                DRM_ERROR("execbuf with invalid offset/length\n");
                return -EINVAL;
        }

        ret = validate_exec_list(exec, args->buffer_count);
        if (ret)
                return ret;

        switch (args->flags & I915_EXEC_RING_MASK) {
        case I915_EXEC_DEFAULT:
        case I915_EXEC_RENDER:
                ring = &dev_priv->ring[RCS];
                break;
        case I915_EXEC_BSD:
                if (!HAS_BSD(dev)) {
                        DRM_ERROR("execbuf with invalid ring (BSD)\n");
                        return -EINVAL;
                }
                ring = &dev_priv->ring[VCS];
                break;
        case I915_EXEC_BLT:
                if (!HAS_BLT(dev)) {
                        DRM_ERROR("execbuf with invalid ring (BLT)\n");
                        return -EINVAL;
                }
                ring = &dev_priv->ring[BCS];
                break;
        default:
                DRM_ERROR("execbuf with unknown ring: %d\n",
                          (int)(args->flags & I915_EXEC_RING_MASK));
                return -EINVAL;
        }

        mode = args->flags & I915_EXEC_CONSTANTS_MASK;
        switch (mode) {
        case I915_EXEC_CONSTANTS_REL_GENERAL:
        case I915_EXEC_CONSTANTS_ABSOLUTE:
        case I915_EXEC_CONSTANTS_REL_SURFACE:
                if (ring == &dev_priv->ring[RCS] &&
                    mode != dev_priv->relative_constants_mode) {
                        if (INTEL_INFO(dev)->gen < 4)
                                return -EINVAL;

                        if (INTEL_INFO(dev)->gen > 5 &&
                            mode == I915_EXEC_CONSTANTS_REL_SURFACE)
                                return -EINVAL;

                        ret = intel_ring_begin(ring, 4);
                        if (ret)
                                return ret;

                        intel_ring_emit(ring, MI_NOOP);
                        intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
                        intel_ring_emit(ring, INSTPM);
                        intel_ring_emit(ring,
                                        I915_EXEC_CONSTANTS_MASK << 16 | mode);
                        intel_ring_advance(ring);

                        dev_priv->relative_constants_mode = mode;
                }
                break;
        default:
                DRM_ERROR("execbuf with unknown constants: %d\n", mode);
                return -EINVAL;
        }

        if (args->buffer_count < 1) {
                DRM_ERROR("execbuf with %d buffers\n", args->buffer_count);
                return -EINVAL;
        }

        if (args->num_cliprects != 0) {
                if (ring != &dev_priv->ring[RCS]) {
                        DRM_ERROR("clip rectangles are only valid with the render ring\n");
                        return -EINVAL;
                }

                cliprects = kmalloc(args->num_cliprects * sizeof(*cliprects),
                                    GFP_KERNEL);
                if (cliprects == NULL) {
                        ret = -ENOMEM;
                        goto pre_mutex_err;
                }

                if (copy_from_user(cliprects,
                                     (struct drm_clip_rect __user *)(uintptr_t)
                                     args->cliprects_ptr,
                                     sizeof(*cliprects)*args->num_cliprects)) {
                        ret = -EFAULT;
                        goto pre_mutex_err;
                }
        }

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                goto pre_mutex_err;

        if (dev_priv->mm.suspended) {
                mutex_unlock(&dev->struct_mutex);
                ret = -EBUSY;
                goto pre_mutex_err;
        }

        eb = eb_create(args->buffer_count);
        if (eb == NULL) {
                mutex_unlock(&dev->struct_mutex);
                ret = -ENOMEM;
                goto pre_mutex_err;
        }

        /* Look up object handles */
        INIT_LIST_HEAD(&objects);
        for (i = 0; i < args->buffer_count; i++) {
                struct drm_i915_gem_object *obj;

                obj = to_intel_bo(drm_gem_object_lookup(dev, file,
                                                        exec[i].handle));
                if (obj == NULL) {
                        DRM_ERROR("Invalid object handle %d at index %d\n",
                                   exec[i].handle, i);
                        /* prevent error path from reading uninitialized data */
                        ret = -ENOENT;
                        goto err;
                }

                if (!list_empty(&obj->exec_list)) {
                        DRM_ERROR("Object %p [handle %d, index %d] appears more than once in object list\n",
                                   obj, exec[i].handle, i);
                        ret = -EINVAL;
                        goto err;
                }

                list_add_tail(&obj->exec_list, &objects);
                obj->exec_handle = exec[i].handle;
                obj->exec_entry = &exec[i];
                eb_add_object(eb, obj);
        }

        /* take note of the batch buffer before we might reorder the lists */
        batch_obj = list_entry(objects.prev,
                               struct drm_i915_gem_object,
                               exec_list);

        /* Move the objects en-masse into the GTT, evicting if necessary. */
        ret = i915_gem_execbuffer_reserve(ring, file, &objects);
        if (ret)
                goto err;

        /* The objects are in their final locations, apply the relocations. */
        ret = i915_gem_execbuffer_relocate(dev, eb, &objects);
        if (ret) {
                if (ret == -EFAULT) {
                        ret = i915_gem_execbuffer_relocate_slow(dev, file, ring,
                                                                &objects, eb,
                                                                exec,
                                                                args->buffer_count);
                        BUG_ON(!mutex_is_locked(&dev->struct_mutex));
                }
                if (ret)
                        goto err;
        }

        /* Set the pending read domains for the batch buffer to COMMAND */
        if (batch_obj->base.pending_write_domain) {
                DRM_ERROR("Attempting to use self-modifying batch buffer\n");
                ret = -EINVAL;
                goto err;
        }
        batch_obj->base.pending_read_domains |= I915_GEM_DOMAIN_COMMAND;

        ret = i915_gem_execbuffer_move_to_gpu(ring, &objects);
        if (ret)
                goto err;

        ret = i915_gem_execbuffer_wait_for_flips(ring, &objects);
        if (ret)
                goto err;

        seqno = i915_gem_next_request_seqno(ring);
        for (i = 0; i < ARRAY_SIZE(ring->sync_seqno); i++) {
                if (seqno < ring->sync_seqno[i]) {
                        /* The GPU can not handle its semaphore value wrapping,
                         * so every billion or so execbuffers, we need to stall
                         * the GPU in order to reset the counters.
                         */
                        ret = i915_gpu_idle(dev);
                        if (ret)
                                goto err;

                        BUG_ON(ring->sync_seqno[i]);
                }
        }

        trace_i915_gem_ring_dispatch(ring, seqno);

        exec_start = batch_obj->gtt_offset + args->batch_start_offset;
        exec_len = args->batch_len;
        if (cliprects) {
                for (i = 0; i < args->num_cliprects; i++) {
                        ret = i915_emit_box(dev, &cliprects[i],
                                            args->DR1, args->DR4);
                        if (ret)
                                goto err;

                        ret = ring->dispatch_execbuffer(ring,
                                                        exec_start, exec_len);
                        if (ret)
                                goto err;
                }
        } else {
                ret = ring->dispatch_execbuffer(ring, exec_start, exec_len);
                if (ret)
                        goto err;
        }

        i915_gem_execbuffer_move_to_active(&objects, ring, seqno);
        i915_gem_execbuffer_retire_commands(dev, file, ring);

err:
        eb_destroy(eb);
        while (!list_empty(&objects)) {
                struct drm_i915_gem_object *obj;

                obj = list_first_entry(&objects,
                                       struct drm_i915_gem_object,
                                       exec_list);
                list_del_init(&obj->exec_list);
                drm_gem_object_unreference(&obj->base);
        }

        mutex_unlock(&dev->struct_mutex);

pre_mutex_err:
        kfree(cliprects);
        return ret;
}

/*
 * Legacy execbuffer just creates an exec2 list from the original exec object
 * list array and passes it to the real function.
 */
int
i915_gem_execbuffer(struct drm_device *dev, void *data,
                    struct drm_file *file)
{
        struct drm_i915_gem_execbuffer *args = data;
        struct drm_i915_gem_execbuffer2 exec2;
        struct drm_i915_gem_exec_object *exec_list = NULL;
        struct drm_i915_gem_exec_object2 *exec2_list = NULL;
        int ret, i;

        if (args->buffer_count < 1) {
                DRM_ERROR("execbuf with %d buffers\n", args->buffer_count);
                return -EINVAL;
        }

        /* Copy in the exec list from userland */
        exec_list = drm_malloc_ab(sizeof(*exec_list), args->buffer_count);
        exec2_list = drm_malloc_ab(sizeof(*exec2_list), args->buffer_count);
        if (exec_list == NULL || exec2_list == NULL) {
                DRM_ERROR("Failed to allocate exec list for %d buffers\n",
                          args->buffer_count);
                drm_free_large(exec_list);
                drm_free_large(exec2_list);
                return -ENOMEM;
        }
        ret = copy_from_user(exec_list,
                             (struct drm_i915_relocation_entry __user *)
                             (uintptr_t) args->buffers_ptr,
                             sizeof(*exec_list) * args->buffer_count);
        if (ret != 0) {
                DRM_ERROR("copy %d exec entries failed %d\n",
                          args->buffer_count, ret);
                drm_free_large(exec_list);
                drm_free_large(exec2_list);
                return -EFAULT;
        }

        for (i = 0; i < args->buffer_count; i++) {
                exec2_list[i].handle = exec_list[i].handle;
                exec2_list[i].relocation_count = exec_list[i].relocation_count;
                exec2_list[i].relocs_ptr = exec_list[i].relocs_ptr;
                exec2_list[i].alignment = exec_list[i].alignment;
                exec2_list[i].offset = exec_list[i].offset;
                if (INTEL_INFO(dev)->gen < 4)
                        exec2_list[i].flags = EXEC_OBJECT_NEEDS_FENCE;
                else
                        exec2_list[i].flags = 0;
        }

        exec2.buffers_ptr = args->buffers_ptr;
        exec2.buffer_count = args->buffer_count;
        exec2.batch_start_offset = args->batch_start_offset;
        exec2.batch_len = args->batch_len;
        exec2.DR1 = args->DR1;
        exec2.DR4 = args->DR4;
        exec2.num_cliprects = args->num_cliprects;
        exec2.cliprects_ptr = args->cliprects_ptr;
        exec2.flags = I915_EXEC_RENDER;

        ret = i915_gem_do_execbuffer(dev, data, file, &exec2, exec2_list);
        if (!ret) {
                /* Copy the new buffer offsets back to the user's exec list. */
                for (i = 0; i < args->buffer_count; i++)
                        exec_list[i].offset = exec2_list[i].offset;
                /* ... and back out to userspace */
                ret = copy_to_user((struct drm_i915_relocation_entry __user *)
                                   (uintptr_t) args->buffers_ptr,
                                   exec_list,
                                   sizeof(*exec_list) * args->buffer_count);
                if (ret) {
                        ret = -EFAULT;
                        DRM_ERROR("failed to copy %d exec entries "
                                  "back to user (%d)\n",
                                  args->buffer_count, ret);
                }
        }

        drm_free_large(exec_list);
        drm_free_large(exec2_list);
        return ret;
}

int
i915_gem_execbuffer2(struct drm_device *dev, void *data,
                     struct drm_file *file)
{
        struct drm_i915_gem_execbuffer2 *args = data;
        struct drm_i915_gem_exec_object2 *exec2_list = NULL;
        int ret;

        if (args->buffer_count < 1) {
                DRM_ERROR("execbuf2 with %d buffers\n", args->buffer_count);
                return -EINVAL;
        }

        exec2_list = drm_malloc_ab(sizeof(*exec2_list), args->buffer_count);
        if (exec2_list == NULL) {
                DRM_ERROR("Failed to allocate exec list for %d buffers\n",
                          args->buffer_count);
                return -ENOMEM;
        }
        ret = copy_from_user(exec2_list,
                             (struct drm_i915_relocation_entry __user *)
                             (uintptr_t) args->buffers_ptr,
                             sizeof(*exec2_list) * args->buffer_count);
        if (ret != 0) {
                DRM_ERROR("copy %d exec entries failed %d\n",
                          args->buffer_count, ret);
                drm_free_large(exec2_list);
                return -EFAULT;
        }

        ret = i915_gem_do_execbuffer(dev, data, file, args, exec2_list);
        if (!ret) {
                /* Copy the new buffer offsets back to the user's exec list. */
                ret = copy_to_user((struct drm_i915_relocation_entry __user *)
                                   (uintptr_t) args->buffers_ptr,
                                   exec2_list,
                                   sizeof(*exec2_list) * args->buffer_count);
                if (ret) {
                        ret = -EFAULT;
                        DRM_ERROR("failed to copy %d exec entries "
                                  "back to user (%d)\n",
                                  args->buffer_count, ret);
                }
        }

        drm_free_large(exec2_list);
        return ret;
}