drm: GEM mmap support

Add core support for mapping of GEM objects.  Drivers should provide a
vm_operations_struct if they want to support page faulting of objects.
The code for handling GEM object offsets was taken from TTM, which was
written by Thomas Hellström.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_bufs.c

@@ -261,6 +261,9 @@ static int drm_addmap_core(struct drm_device * dev, unsigned int offset,
 		}
 		DRM_DEBUG("AGP offset = 0x%08lx, size = 0x%08lx\n", map->offset, map->size);
 
+		break;
+	case _DRM_GEM:
+		DRM_ERROR("tried to rmmap GEM object\n");
 		break;
 	}
 	case _DRM_SCATTER_GATHER:
@@ -429,6 +432,9 @@ int drm_rmmap_locked(struct drm_device *dev, drm_local_map_t *map)
 		dmah.size = map->size;
 		__drm_pci_free(dev, &dmah);
 		break;
+	case _DRM_GEM:
+		DRM_ERROR("tried to rmmap GEM object\n");
+		break;
 	}
 	drm_free(map, sizeof(*map), DRM_MEM_MAPS);
 

drivers/gpu/drm/drm_drv.c

@@ -209,6 +209,7 @@ int drm_lastclose(struct drm_device * dev)
 	if (drm_core_check_feature(dev, DRIVER_HAVE_DMA))
 		drm_dma_takedown(dev);
 
+	dev->dev_mapping = NULL;
 	mutex_unlock(&dev->struct_mutex);
 
 	DRM_DEBUG("lastclose completed\n");
@@ -273,6 +274,8 @@ EXPORT_SYMBOL(drm_init);
  */
 static void drm_cleanup(struct drm_device * dev)
 {
+	struct drm_driver *driver = dev->driver;
+
 	DRM_DEBUG("\n");
 
 	if (!dev) {
@@ -304,6 +307,9 @@ static void drm_cleanup(struct drm_device * dev)
 	drm_ht_remove(&dev->map_hash);
 	drm_ctxbitmap_cleanup(dev);
 
+	if (driver->driver_features & DRIVER_GEM)
+		drm_gem_destroy(dev);
+
 	drm_put_minor(&dev->primary);
 	if (drm_put_dev(dev))
 		DRM_ERROR("Cannot unload module\n");

drivers/gpu/drm/drm_fops.c

@@ -133,11 +133,21 @@ int drm_open(struct inode *inode, struct file *filp)
 		spin_lock(&dev->count_lock);
 		if (!dev->open_count++) {
 			spin_unlock(&dev->count_lock);
-			return drm_setup(dev);
+			retcode = drm_setup(dev);
+			goto out;
 		}
 		spin_unlock(&dev->count_lock);
 	}
 
+out:
+	mutex_lock(&dev->struct_mutex);
+	if (dev->dev_mapping == NULL)
+		dev->dev_mapping = inode->i_mapping;
+	else if (dev->dev_mapping != inode->i_mapping)
+		WARN(1, "dev->dev_mapping not inode mapping (%p expected %p)\n",
+		     dev->dev_mapping, inode->i_mapping);
+	mutex_unlock(&dev->struct_mutex);
+
 	return retcode;
 }
 EXPORT_SYMBOL(drm_open);

drivers/gpu/drm/drm_gem.c

@@ -64,6 +64,13 @@
  * up at a later date, and as our interface with shmfs for memory allocation.
  */
 
+/*
+ * We make up offsets for buffer objects so we can recognize them at
+ * mmap time.
+ */
+#define DRM_FILE_PAGE_OFFSET_START ((0xFFFFFFFFUL >> PAGE_SHIFT) + 1)
+#define DRM_FILE_PAGE_OFFSET_SIZE ((0xFFFFFFFFUL >> PAGE_SHIFT) * 16)
+
 /**
  * Initialize the GEM device fields
  */
@@ -71,6 +78,8 @@
 int
 drm_gem_init(struct drm_device *dev)
 {
+	struct drm_gem_mm *mm;
+
 	spin_lock_init(&dev->object_name_lock);
 	idr_init(&dev->object_name_idr);
 	atomic_set(&dev->object_count, 0);
@@ -79,9 +88,41 @@ drm_gem_init(struct drm_device *dev)
 	atomic_set(&dev->pin_memory, 0);
 	atomic_set(&dev->gtt_count, 0);
 	atomic_set(&dev->gtt_memory, 0);
+
+	mm = drm_calloc(1, sizeof(struct drm_gem_mm), DRM_MEM_MM);
+	if (!mm) {
+		DRM_ERROR("out of memory\n");
+		return -ENOMEM;
+	}
+
+	dev->mm_private = mm;
+
+	if (drm_ht_create(&mm->offset_hash, 19)) {
+		drm_free(mm, sizeof(struct drm_gem_mm), DRM_MEM_MM);
+		return -ENOMEM;
+	}
+
+	if (drm_mm_init(&mm->offset_manager, DRM_FILE_PAGE_OFFSET_START,
+			DRM_FILE_PAGE_OFFSET_SIZE)) {
+		drm_free(mm, sizeof(struct drm_gem_mm), DRM_MEM_MM);
+		drm_ht_remove(&mm->offset_hash);
+		return -ENOMEM;
+	}
+
 	return 0;
 }
 
+void
+drm_gem_destroy(struct drm_device *dev)
+{
+	struct drm_gem_mm *mm = dev->mm_private;
+
+	drm_mm_takedown(&mm->offset_manager);
+	drm_ht_remove(&mm->offset_hash);
+	drm_free(mm, sizeof(struct drm_gem_mm), DRM_MEM_MM);
+	dev->mm_private = NULL;
+}
+
 /**
  * Allocate a GEM object of the specified size with shmfs backing store
  */
@@ -419,3 +460,71 @@ drm_gem_object_handle_free(struct kref *kref)
 }
 EXPORT_SYMBOL(drm_gem_object_handle_free);
 
+/**
+ * drm_gem_mmap - memory map routine for GEM objects
+ * @filp: DRM file pointer
+ * @vma: VMA for the area to be mapped
+ *
+ * If a driver supports GEM object mapping, mmap calls on the DRM file
+ * descriptor will end up here.
+ *
+ * If we find the object based on the offset passed in (vma->vm_pgoff will
+ * contain the fake offset we created when the GTT map ioctl was called on
+ * the object), we set up the driver fault handler so that any accesses
+ * to the object can be trapped, to perform migration, GTT binding, surface
+ * register allocation, or performance monitoring.
+ */
+int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	struct drm_file *priv = filp->private_data;
+	struct drm_device *dev = priv->minor->dev;
+	struct drm_gem_mm *mm = dev->mm_private;
+	struct drm_map *map = NULL;
+	struct drm_gem_object *obj;
+	struct drm_hash_item *hash;
+	unsigned long prot;
+	int ret = 0;
+
+	mutex_lock(&dev->struct_mutex);
+
+	if (drm_ht_find_item(&mm->offset_hash, vma->vm_pgoff, &hash)) {
+		mutex_unlock(&dev->struct_mutex);
+		return drm_mmap(filp, vma);
+	}
+
+	map = drm_hash_entry(hash, struct drm_map_list, hash)->map;
+	if (!map ||
+	    ((map->flags & _DRM_RESTRICTED) && !capable(CAP_SYS_ADMIN))) {
+		ret =  -EPERM;
+		goto out_unlock;
+	}
+
+	/* Check for valid size. */
+	if (map->size < vma->vm_end - vma->vm_start) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	obj = map->handle;
+	if (!obj->dev->driver->gem_vm_ops) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	vma->vm_flags |= VM_RESERVED | VM_IO | VM_PFNMAP | VM_DONTEXPAND;
+	vma->vm_ops = obj->dev->driver->gem_vm_ops;
+	vma->vm_private_data = map->handle;
+	/* FIXME: use pgprot_writecombine when available */
+	prot = pgprot_val(vma->vm_page_prot);
+	prot |= _PAGE_CACHE_WC;
+	vma->vm_page_prot = __pgprot(prot);
+
+	vma->vm_file = filp;	/* Needed for drm_vm_open() */
+	drm_vm_open_locked(vma);
+
+out_unlock:
+	mutex_unlock(&dev->struct_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_mmap);

drivers/gpu/drm/drm_hashtab.c

@@ -127,6 +127,7 @@ int drm_ht_insert_item(struct drm_open_hash *ht, struct drm_hash_item *item)
 	}
 	return 0;
 }
+EXPORT_SYMBOL(drm_ht_insert_item);
 
 /*
  * Just insert an item and return any "bits" bit key that hasn't been
@@ -188,6 +189,7 @@ int drm_ht_remove_item(struct drm_open_hash *ht, struct drm_hash_item *item)
 	ht->fill--;
 	return 0;
 }
+EXPORT_SYMBOL(drm_ht_remove_item);
 
 void drm_ht_remove(struct drm_open_hash *ht)
 {

drivers/gpu/drm/drm_vm.c

@@ -267,6 +267,9 @@ static void drm_vm_shm_close(struct vm_area_struct *vma)
 				dmah.size = map->size;
 				__drm_pci_free(dev, &dmah);
 				break;
+			case _DRM_GEM:
+				DRM_ERROR("tried to rmmap GEM object\n");
+				break;
 			}
 			drm_free(map, sizeof(*map), DRM_MEM_MAPS);
 		}
@@ -399,7 +402,7 @@ static struct vm_operations_struct drm_vm_sg_ops = {
  * Create a new drm_vma_entry structure as the \p vma private data entry and
  * add it to drm_device::vmalist.
  */
-static void drm_vm_open_locked(struct vm_area_struct *vma)
+void drm_vm_open_locked(struct vm_area_struct *vma)
 {
 	struct drm_file *priv = vma->vm_file->private_data;
 	struct drm_device *dev = priv->minor->dev;
@@ -540,7 +543,7 @@ EXPORT_SYMBOL(drm_core_get_reg_ofs);
  * according to the mapping type and remaps the pages. Finally sets the file
  * pointer and calls vm_open().
  */
-static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
+int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
 {
 	struct drm_file *priv = filp->private_data;
 	struct drm_device *dev = priv->minor->dev;

include/drm/drm.h

@@ -173,6 +173,7 @@ enum drm_map_type {
 	_DRM_AGP = 3,		  /**< AGP/GART */
 	_DRM_SCATTER_GATHER = 4,  /**< Scatter/gather memory for PCI DMA */
 	_DRM_CONSISTENT = 5,	  /**< Consistent memory for PCI DMA */
+	_DRM_GEM = 6,		  /**< GEM object */
 };
 
 /**

include/drm/drmP.h

@@ -528,6 +528,7 @@ struct drm_map_list {
 	struct drm_map *map;			/**< mapping */
 	uint64_t user_token;
 	struct drm_master *master;
+	struct drm_mm_node *file_offset_node;	/**< fake offset */
 };
 
 typedef struct drm_map drm_local_map_t;
@@ -567,6 +568,14 @@ struct drm_ati_pcigart_info {
 	int table_size;
 };
 
+/**
+ * GEM specific mm private for tracking GEM objects
+ */
+struct drm_gem_mm {
+	struct drm_mm offset_manager;	/**< Offset mgmt for buffer objects */
+	struct drm_open_hash offset_hash; /**< User token hash table for maps */
+};
+
 /**
  * This structure defines the drm_mm memory object, which will be used by the
  * DRM for its buffer objects.
@@ -584,6 +593,9 @@ struct drm_gem_object {
 	/** File representing the shmem storage */
 	struct file *filp;
 
+	/* Mapping info for this object */
+	struct drm_map_list map_list;
+
 	/**
 	 * Size of the object, in bytes.  Immutable over the object's
 	 * lifetime.
@@ -758,6 +770,9 @@ struct drm_driver {
 	int (*gem_init_object) (struct drm_gem_object *obj);
 	void (*gem_free_object) (struct drm_gem_object *obj);
 
+	/* Driver private ops for this object */
+	struct vm_operations_struct *gem_vm_ops;
+
 	int major;
 	int minor;
 	int patchlevel;
@@ -910,6 +925,8 @@ struct drm_device {
 	struct drm_sg_mem *sg;	/**< Scatter gather memory */
 	int num_crtcs;                  /**< Number of CRTCs on this device */
 	void *dev_private;		/**< device private data */
+	void *mm_private;
+	struct address_space *dev_mapping;
 	struct drm_sigdata sigdata;	   /**< For block_all_signals */
 	sigset_t sigmask;
 
@@ -1026,6 +1043,8 @@ extern int drm_release(struct inode *inode, struct file *filp);
 
 				/* Mapping support (drm_vm.h) */
 extern int drm_mmap(struct file *filp, struct vm_area_struct *vma);
+extern int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma);
+extern void drm_vm_open_locked(struct vm_area_struct *vma);
 extern unsigned long drm_core_get_map_ofs(struct drm_map * map);
 extern unsigned long drm_core_get_reg_ofs(struct drm_device *dev);
 extern unsigned int drm_poll(struct file *filp, struct poll_table_struct *wait);
@@ -1287,10 +1306,12 @@ extern int drm_mm_add_space_to_tail(struct drm_mm *mm, unsigned long size);
 
 /* Graphics Execution Manager library functions (drm_gem.c) */
 int drm_gem_init(struct drm_device *dev);
+void drm_gem_destroy(struct drm_device *dev);
 void drm_gem_object_free(struct kref *kref);
 struct drm_gem_object *drm_gem_object_alloc(struct drm_device *dev,
 					    size_t size);
 void drm_gem_object_handle_free(struct kref *kref);
+int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma);
 
 static inline void
 drm_gem_object_reference(struct drm_gem_object *obj)