[PATCH 2/3] drm/vgem: Fix mmaping

[Chris Wilson <chris@chris-wilson.co.uk>]

The vGEM mmap code has bitrotted slightly and now immediately BUGs.
Since vGEM was last updated, there are new core GEM facilities to
provide more common functions, so let's use those here.

Testcase: igt/vgem_basic/mmap
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/vgem/vgem_drv.c | 163 +++++++++++++++-------------------------
 drivers/gpu/drm/vgem/vgem_drv.h |   6 --
 2 files changed, 61 insertions(+), 108 deletions(-)

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 1b4cc8b27080..4747b7f98e7a 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -42,81 +42,39 @@
 #define DRIVER_MAJOR	1
 #define DRIVER_MINOR	0
 
-void vgem_gem_put_pages(struct drm_vgem_gem_object *obj)
-{
-	drm_gem_put_pages(&obj->base, obj->pages, false, false);
-	obj->pages = NULL;
-}
-
 static void vgem_gem_free_object(struct drm_gem_object *obj)
 {
 	struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);
 
 	drm_gem_free_mmap_offset(obj);
-
-	if (vgem_obj->use_dma_buf && obj->dma_buf) {
-		dma_buf_put(obj->dma_buf);
-		obj->dma_buf = NULL;
-	}
-
 	drm_gem_object_release(obj);
-
-	if (vgem_obj->pages)
-		vgem_gem_put_pages(vgem_obj);
-
-	vgem_obj->pages = NULL;
-
 	kfree(vgem_obj);
 }
 
-int vgem_gem_get_pages(struct drm_vgem_gem_object *obj)
-{
-	struct page **pages;
-
-	if (obj->pages || obj->use_dma_buf)
-		return 0;
-
-	pages = drm_gem_get_pages(&obj->base);
-	if (IS_ERR(pages)) {
-		return PTR_ERR(pages);
-	}
-
-	obj->pages = pages;
-
-	return 0;
-}
-
 static int vgem_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct drm_vgem_gem_object *obj = vma->vm_private_data;
-	loff_t num_pages;
-	pgoff_t page_offset;
-	int ret;
-
 	/* We don't use vmf->pgoff since that has the fake offset */
-	page_offset = ((unsigned long)vmf->virtual_address - vma->vm_start) >>
-		PAGE_SHIFT;
-
-	num_pages = DIV_ROUND_UP(obj->base.size, PAGE_SIZE);
-
-	if (page_offset > num_pages)
-		return VM_FAULT_SIGBUS;
-
-	ret = vm_insert_page(vma, (unsigned long)vmf->virtual_address,
-			     obj->pages[page_offset]);
-	switch (ret) {
-	case 0:
-		return VM_FAULT_NOPAGE;
-	case -ENOMEM:
-		return VM_FAULT_OOM;
-	case -EBUSY:
-		return VM_FAULT_RETRY;
-	case -EFAULT:
-	case -EINVAL:
-		return VM_FAULT_SIGBUS;
-	default:
-		WARN_ON(1);
-		return VM_FAULT_SIGBUS;
+	unsigned long vaddr = (unsigned long)vmf->virtual_address;
+	struct page *page;
+
+	page = shmem_read_mapping_page(file_inode(obj->base.filp)->i_mapping,
+				       (vaddr - vma->vm_start) >> PAGE_SHIFT);
+	if (!IS_ERR(page)) {
+		vmf->page = page;
+		return VM_FAULT_LOCKED;
+	} else switch (PTR_ERR(page)) {
+		case -ENOSPC:
+		case -ENOMEM:
+			return VM_FAULT_OOM;
+		case -EBUSY:
+			return VM_FAULT_RETRY;
+		case -EFAULT:
+		case -EINVAL:
+			return VM_FAULT_SIGBUS;
+		default:
+			WARN_ON_ONCE(PTR_ERR(page));
+			return VM_FAULT_SIGBUS;
 	}
 }
 
@@ -134,57 +92,43 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
 					      unsigned long size)
 {
 	struct drm_vgem_gem_object *obj;
-	struct drm_gem_object *gem_object;
-	int err;
-
-	size = roundup(size, PAGE_SIZE);
+	int ret;
 
 	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
 	if (!obj)
 		return ERR_PTR(-ENOMEM);
 
-	gem_object = &obj->base;
-
-	err = drm_gem_object_init(dev, gem_object, size);
-	if (err)
-		goto out;
-
-	err = vgem_gem_get_pages(obj);
-	if (err)
-		goto out;
-
-	err = drm_gem_handle_create(file, gem_object, handle);
-	if (err)
-		goto handle_out;
+	ret = drm_gem_object_init(dev, &obj->base, roundup(size, PAGE_SIZE));
+	if (ret)
+		goto err_free;
 
-	drm_gem_object_unreference_unlocked(gem_object);
+	ret = drm_gem_handle_create(file, &obj->base, handle);
+	drm_gem_object_unreference_unlocked(&obj->base);
+	if (ret)
+		goto err;
 
-	return gem_object;
+	return &obj->base;
 
-handle_out:
-	drm_gem_object_release(gem_object);
-out:
+err_free:
 	kfree(obj);
-	return ERR_PTR(err);
+err:
+	return ERR_PTR(ret);
 }
 
 static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
 				struct drm_mode_create_dumb *args)
 {
 	struct drm_gem_object *gem_object;
-	uint64_t size;
-	uint64_t pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
+	u64 pitch, size;
 
+	pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
 	size = args->height * pitch;
 	if (size == 0)
 		return -EINVAL;
 
 	gem_object = vgem_gem_create(dev, file, &args->handle, size);
-
-	if (IS_ERR(gem_object)) {
-		DRM_DEBUG_DRIVER("object creation failed\n");
+	if (IS_ERR(gem_object))
 		return PTR_ERR(gem_object);
-	}
 
 	args->size = gem_object->size;
 	args->pitch = pitch;
@@ -194,26 +138,26 @@ static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
 	return 0;
 }
 
-int vgem_gem_dumb_map(struct drm_file *file, struct drm_device *dev,
-		      uint32_t handle, uint64_t *offset)
+static int vgem_gem_dumb_map(struct drm_file *file, struct drm_device *dev,
+			     uint32_t handle, uint64_t *offset)
 {
-	int ret = 0;
 	struct drm_gem_object *obj;
+	int ret;
 
 	obj = drm_gem_object_lookup(file, handle);
 	if (!obj)
 		return -ENOENT;
 
+	if (!obj->filp) {
+		ret = -EINVAL;
+		goto unref;
+	}
+
 	ret = drm_gem_create_mmap_offset(obj);
 	if (ret)
 		goto unref;
 
-	BUG_ON(!obj->filp);
-
-	obj->filp->private_data = obj;
-
 	*offset = drm_vma_node_offset_addr(&obj->vma_node);
-
 unref:
 	drm_gem_object_unreference_unlocked(obj);
 
@@ -223,10 +167,26 @@ unref:
 static struct drm_ioctl_desc vgem_ioctls[] = {
 };
 
+static int vgem_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	unsigned long flags = vma->vm_flags;
+	int ret;
+
+	ret = drm_gem_mmap(filp, vma);
+	if (ret)
+		return ret;
+
+	/* Keep the WC mmaping set by drm_gem_mmap() but our pages
+	 * are ordinary and not special.
+	 */
+	vma->vm_flags = flags | VM_DONTEXPAND | VM_DONTDUMP;
+	return 0;
+}
+
 static const struct file_operations vgem_driver_fops = {
 	.owner		= THIS_MODULE,
 	.open		= drm_open,
-	.mmap		= drm_gem_mmap,
+	.mmap		= vgem_mmap,
 	.poll		= drm_poll,
 	.read		= drm_read,
 	.unlocked_ioctl = drm_ioctl,
@@ -248,7 +208,7 @@ static struct drm_driver vgem_driver = {
 	.minor	= DRIVER_MINOR,
 };
 
-struct drm_device *vgem_device;
+static struct drm_device *vgem_device;
 
 static int __init vgem_init(void)
 {
@@ -263,7 +223,6 @@ static int __init vgem_init(void)
 	drm_dev_set_unique(vgem_device, "vgem");
 
 	ret  = drm_dev_register(vgem_device, 0);
-
 	if (ret)
 		goto out_unref;
 
diff --git a/drivers/gpu/drm/vgem/vgem_drv.h b/drivers/gpu/drm/vgem/vgem_drv.h
index e9f92f7ee275..988cbaae7588 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.h
+++ b/drivers/gpu/drm/vgem/vgem_drv.h
@@ -35,12 +35,6 @@
 #define to_vgem_bo(x) container_of(x, struct drm_vgem_gem_object, base)
 struct drm_vgem_gem_object {
 	struct drm_gem_object base;
-	struct page **pages;
-	bool use_dma_buf;
 };
 
-/* vgem_drv.c */
-extern void vgem_gem_put_pages(struct drm_vgem_gem_object *obj);
-extern int vgem_gem_get_pages(struct drm_vgem_gem_object *obj);
-
 #endif
-- 
2.8.1

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