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>

6 files changed, 139 insertions, 3 deletions

diff --git a/drivers/gpu/drm/drm_bufs.c b/drivers/gpu/drm/drm_bufs.c
index dc3ce3e0a0a4..7fb690bcd492 100644
--- a/drivers/gpu/drm/drm_bufs.c
+++ b/drivers/gpu/drm/drm_bufs.c
@@ -262,6 +262,9 @@ 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:
                 if (!dev->sg) {
@@ -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);
 
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 9f04ca37df6d..98a781375f60 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/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");
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index f2285237df49..3a6c439652a5 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/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);
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index ccd1afdede02..b3939de6affd 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/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);
diff --git a/drivers/gpu/drm/drm_hashtab.c b/drivers/gpu/drm/drm_hashtab.c
index 33160673a7b7..af539f7d87dd 100644
--- a/drivers/gpu/drm/drm_hashtab.c
+++ b/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)
 {
diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
index c234c6f24a8d..3ffae021d280 100644
--- a/drivers/gpu/drm/drm_vm.c
+++ b/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;