drm/i915: Avoid vmallocing a buffer for the relocations
authorChris Wilson <chris@chris-wilson.co.uk>
Thu, 14 Oct 2010 11:10:41 +0000 (12:10 +0100)
committerChris Wilson <chris@chris-wilson.co.uk>
Tue, 19 Oct 2010 08:18:36 +0000 (09:18 +0100)
... perform an access validation check up front instead and copy them in
on-demand, during i915_gem_object_pin_and_relocate(). As around 20% of
the CPU overhead may be spent inside vmalloc for the relocation entries
when submitting an execbuffer [for x11perf -aa10text], the savings are
considerable and result in around a 10% throughput increase [for glyphs].

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
drivers/gpu/drm/i915/i915_gem.c

index 72ab3032300ad6c0b6b10a2b4274d7f39ec814d5..67998e8a2d7010928ce688fd9049f7133d5fcfc7 100644 (file)
@@ -3291,12 +3291,12 @@ i915_gem_object_set_cpu_read_domain_range(struct drm_gem_object *obj,
 static int
 i915_gem_object_pin_and_relocate(struct drm_gem_object *obj,
                                 struct drm_file *file_priv,
-                                struct drm_i915_gem_exec_object2 *entry,
-                                struct drm_i915_gem_relocation_entry *relocs)
+                                struct drm_i915_gem_exec_object2 *entry)
 {
        struct drm_device *dev = obj->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv = to_intel_bo(obj);
+       struct drm_i915_gem_relocation_entry __user *user_relocs;
        int i, ret;
        void __iomem *reloc_page;
        bool need_fence;
@@ -3337,15 +3337,24 @@ i915_gem_object_pin_and_relocate(struct drm_gem_object *obj,
        /* Apply the relocations, using the GTT aperture to avoid cache
         * flushing requirements.
         */
+       user_relocs = (void __user *)(uintptr_t)entry->relocs_ptr;
        for (i = 0; i < entry->relocation_count; i++) {
-               struct drm_i915_gem_relocation_entry *reloc= &relocs[i];
+               struct drm_i915_gem_relocation_entry reloc;
                struct drm_gem_object *target_obj;
                struct drm_i915_gem_object *target_obj_priv;
                uint32_t reloc_val, reloc_offset;
                uint32_t __iomem *reloc_entry;
 
+               ret = __copy_from_user_inatomic(&reloc,
+                                               user_relocs+i,
+                                               sizeof(reloc));
+               if (ret) {
+                       i915_gem_object_unpin(obj);
+                       return -EFAULT;
+               }
+
                target_obj = drm_gem_object_lookup(obj->dev, file_priv,
-                                                  reloc->target_handle);
+                                                  reloc.target_handle);
                if (target_obj == NULL) {
                        i915_gem_object_unpin(obj);
                        return -ENOENT;
@@ -3358,13 +3367,13 @@ i915_gem_object_pin_and_relocate(struct drm_gem_object *obj,
                         "presumed %08x delta %08x\n",
                         __func__,
                         obj,
-                        (int) reloc->offset,
-                        (int) reloc->target_handle,
-                        (int) reloc->read_domains,
-                        (int) reloc->write_domain,
+                        (int) reloc.offset,
+                        (int) reloc.target_handle,
+                        (int) reloc.read_domains,
+                        (int) reloc.write_domain,
                         (int) target_obj_priv->gtt_offset,
-                        (int) reloc->presumed_offset,
-                        reloc->delta);
+                        (int) reloc.presumed_offset,
+                        reloc.delta);
 #endif
 
                /* The target buffer should have appeared before us in the
@@ -3372,89 +3381,89 @@ i915_gem_object_pin_and_relocate(struct drm_gem_object *obj,
                 */
                if (target_obj_priv->gtt_space == NULL) {
                        DRM_ERROR("No GTT space found for object %d\n",
-                                 reloc->target_handle);
+                                 reloc.target_handle);
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
                }
 
                /* Validate that the target is in a valid r/w GPU domain */
-               if (reloc->write_domain & (reloc->write_domain - 1)) {
+               if (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);
+                                 obj, reloc.target_handle,
+                                 (int) reloc.offset,
+                                 reloc.read_domains,
+                                 reloc.write_domain);
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
                }
-               if (reloc->write_domain & I915_GEM_DOMAIN_CPU ||
-                   reloc->read_domains & I915_GEM_DOMAIN_CPU) {
+               if (reloc.write_domain & I915_GEM_DOMAIN_CPU ||
+                   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);
+                                 obj, reloc.target_handle,
+                                 (int) reloc.offset,
+                                 reloc.read_domains,
+                                 reloc.write_domain);
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
                }
-               if (reloc->write_domain && target_obj->pending_write_domain &&
-                   reloc->write_domain != target_obj->pending_write_domain) {
+               if (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,
+                                 obj, reloc.target_handle,
+                                 (int) reloc.offset,
+                                 reloc.write_domain,
                                  target_obj->pending_write_domain);
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
                }
 
-               target_obj->pending_read_domains |= reloc->read_domains;
-               target_obj->pending_write_domain |= reloc->write_domain;
+               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_obj_priv->gtt_offset == reloc->presumed_offset) {
+               if (target_obj_priv->gtt_offset == reloc.presumed_offset) {
                        drm_gem_object_unreference(target_obj);
                        continue;
                }
 
                /* Check that the relocation address is valid... */
-               if (reloc->offset > obj->size - 4) {
+               if (reloc.offset > obj->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->size);
+                                 obj, reloc.target_handle,
+                                 (int) reloc.offset, (int) obj->size);
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
                }
-               if (reloc->offset & 3) {
+               if (reloc.offset & 3) {
                        DRM_ERROR("Relocation not 4-byte aligned: "
                                  "obj %p target %d offset %d.\n",
-                                 obj, reloc->target_handle,
-                                 (int) reloc->offset);
+                                 obj, reloc.target_handle,
+                                 (int) reloc.offset);
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
                }
 
                /* and points to somewhere within the target object. */
-               if (reloc->delta >= target_obj->size) {
+               if (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);
+                                 obj, reloc.target_handle,
+                                 (int) reloc.delta, (int) target_obj->size);
                        drm_gem_object_unreference(target_obj);
                        i915_gem_object_unpin(obj);
                        return -EINVAL;
@@ -3470,23 +3479,18 @@ i915_gem_object_pin_and_relocate(struct drm_gem_object *obj,
                /* Map the page containing the relocation we're going to
                 * perform.
                 */
-               reloc_offset = obj_priv->gtt_offset + reloc->offset;
+               reloc_offset = obj_priv->gtt_offset + reloc.offset;
                reloc_page = io_mapping_map_atomic_wc(dev_priv->mm.gtt_mapping,
                                                      (reloc_offset &
                                                       ~(PAGE_SIZE - 1)),
                                                      KM_USER0);
                reloc_entry = (uint32_t __iomem *)(reloc_page +
                                                   (reloc_offset & (PAGE_SIZE - 1)));
-               reloc_val = target_obj_priv->gtt_offset + reloc->delta;
+               reloc_val = target_obj_priv->gtt_offset + reloc.delta;
 
                writel(reloc_val, reloc_entry);
                io_mapping_unmap_atomic(reloc_page, KM_USER0);
 
-               /* The updated presumed offset for this entry will be
-                * copied back out to the user.
-                */
-               reloc->presumed_offset = target_obj_priv->gtt_offset;
-
                drm_gem_object_unreference(target_obj);
        }
 
@@ -3551,98 +3555,40 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
 }
 
 static int
-i915_gem_get_relocs_from_user(struct drm_i915_gem_exec_object2 *exec_list,
-                             uint32_t buffer_count,
-                             struct drm_i915_gem_relocation_entry **relocs)
+i915_gem_check_execbuffer(struct drm_i915_gem_execbuffer2 *exec,
+                         uint64_t exec_offset)
 {
-       uint32_t reloc_count = 0, reloc_index = 0, i;
-       int ret;
-
-       *relocs = NULL;
-       for (i = 0; i < buffer_count; i++) {
-               if (reloc_count + exec_list[i].relocation_count < reloc_count)
-                       return -EINVAL;
-               reloc_count += exec_list[i].relocation_count;
-       }
-
-       *relocs = drm_calloc_large(reloc_count, sizeof(**relocs));
-       if (*relocs == NULL) {
-               DRM_ERROR("failed to alloc relocs, count %d\n", reloc_count);
-               return -ENOMEM;
-       }
-
-       for (i = 0; i < buffer_count; i++) {
-               struct drm_i915_gem_relocation_entry __user *user_relocs;
+       uint32_t exec_start, exec_len;
 
-               user_relocs = (void __user *)(uintptr_t)exec_list[i].relocs_ptr;
+       exec_start = (uint32_t) exec_offset + exec->batch_start_offset;
+       exec_len = (uint32_t) exec->batch_len;
 
-               ret = copy_from_user(&(*relocs)[reloc_index],
-                                    user_relocs,
-                                    exec_list[i].relocation_count *
-                                    sizeof(**relocs));
-               if (ret != 0) {
-                       drm_free_large(*relocs);
-                       *relocs = NULL;
-                       return -EFAULT;
-               }
+       if ((exec_start | exec_len) & 0x7)
+               return -EINVAL;
 
-               reloc_index += exec_list[i].relocation_count;
-       }
+       if (!exec_start)
+               return -EINVAL;
 
        return 0;
 }
 
 static int
-i915_gem_put_relocs_to_user(struct drm_i915_gem_exec_object2 *exec_list,
-                           uint32_t buffer_count,
-                           struct drm_i915_gem_relocation_entry *relocs)
+validate_exec_list(struct drm_i915_gem_exec_object2 *exec,
+                  int count)
 {
-       uint32_t reloc_count = 0, i;
-       int ret = 0;
-
-       if (relocs == NULL)
-           return 0;
-
-       for (i = 0; i < buffer_count; i++) {
-               struct drm_i915_gem_relocation_entry __user *user_relocs;
-               int unwritten;
-
-               user_relocs = (void __user *)(uintptr_t)exec_list[i].relocs_ptr;
+       int i;
 
-               unwritten = copy_to_user(user_relocs,
-                                        &relocs[reloc_count],
-                                        exec_list[i].relocation_count *
-                                        sizeof(*relocs));
+       for (i = 0; i < count; i++) {
+               char __user *ptr = (char __user *)(uintptr_t)exec[i].relocs_ptr;
+               size_t length = exec[i].relocation_count * sizeof(struct drm_i915_gem_relocation_entry);
 
-               if (unwritten) {
-                       ret = -EFAULT;
-                       goto err;
-               }
+               if (!access_ok(VERIFY_READ, ptr, length))
+                       return -EFAULT;
 
-               reloc_count += exec_list[i].relocation_count;
+               if (fault_in_pages_readable(ptr, length))
+                       return -EFAULT;
        }
 
-err:
-       drm_free_large(relocs);
-
-       return ret;
-}
-
-static int
-i915_gem_check_execbuffer (struct drm_i915_gem_execbuffer2 *exec,
-                          uint64_t exec_offset)
-{
-       uint32_t exec_start, exec_len;
-
-       exec_start = (uint32_t) exec_offset + exec->batch_start_offset;
-       exec_len = (uint32_t) exec->batch_len;
-
-       if ((exec_start | exec_len) & 0x7)
-               return -EINVAL;
-
-       if (!exec_start)
-               return -EINVAL;
-
        return 0;
 }
 
@@ -3657,11 +3603,9 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
        struct drm_gem_object *batch_obj;
        struct drm_i915_gem_object *obj_priv;
        struct drm_clip_rect *cliprects = NULL;
-       struct drm_i915_gem_relocation_entry *relocs = NULL;
        struct drm_i915_gem_request *request = NULL;
-       int ret, ret2, i, pinned = 0;
+       int ret, i, pinned = 0;
        uint64_t exec_offset;
-       uint32_t reloc_index;
        int pin_tries, flips;
 
        struct intel_ring_buffer *ring = NULL;
@@ -3670,6 +3614,10 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
        if (ret)
                return ret;
 
+       ret = validate_exec_list(exec_list, args->buffer_count);
+       if (ret)
+               return ret;
+
 #if WATCH_EXEC
        DRM_INFO("buffers_ptr %d buffer_count %d len %08x\n",
                  (int) args->buffers_ptr, args->buffer_count, args->batch_len);
@@ -3722,11 +3670,6 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
                goto pre_mutex_err;
        }
 
-       ret = i915_gem_get_relocs_from_user(exec_list, args->buffer_count,
-                                           &relocs);
-       if (ret != 0)
-               goto pre_mutex_err;
-
        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                goto pre_mutex_err;
@@ -3765,19 +3708,16 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
        /* Pin and relocate */
        for (pin_tries = 0; ; pin_tries++) {
                ret = 0;
-               reloc_index = 0;
 
                for (i = 0; i < args->buffer_count; i++) {
                        object_list[i]->pending_read_domains = 0;
                        object_list[i]->pending_write_domain = 0;
                        ret = i915_gem_object_pin_and_relocate(object_list[i],
                                                               file_priv,
-                                                              &exec_list[i],
-                                                              &relocs[reloc_index]);
+                                                              &exec_list[i]);
                        if (ret)
                                break;
                        pinned = i + 1;
-                       reloc_index += exec_list[i].relocation_count;
                }
                /* success */
                if (ret == 0)
@@ -3967,20 +3907,6 @@ err:
        mutex_unlock(&dev->struct_mutex);
 
 pre_mutex_err:
-       /* Copy the updated relocations out regardless of current error
-        * state.  Failure to update the relocs would mean that the next
-        * time userland calls execbuf, it would do so with presumed offset
-        * state that didn't match the actual object state.
-        */
-       ret2 = i915_gem_put_relocs_to_user(exec_list, args->buffer_count,
-                                          relocs);
-       if (ret2 != 0) {
-               DRM_ERROR("Failed to copy relocations back out: %d\n", ret2);
-
-               if (ret == 0)
-                       ret = ret2;
-       }
-
        drm_free_large(object_list);
        kfree(cliprects);
        kfree(request);