Commit 83b8a6f2 authored by Rob Herring's avatar Rob Herring
Browse files

drm/gem: Fix mmap fake offset handling for drm_gem_object_funcs.mmap 



Commit c40069cb ("drm: add mmap() to drm_gem_object_funcs")
introduced a GEM object mmap() hook which is expected to subtract the
fake offset from vm_pgoff. However, for mmap() on dmabufs, there is not
a fake offset.

To fix this, let's always call mmap() object callback with an offset of 0,
and leave it up to drm_gem_mmap_obj() to remove the fake offset.

TTM still needs the fake offset, so we have to add it back until that's
fixed.

Fixes: c40069cb ("drm: add mmap() to drm_gem_object_funcs")
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: default avatarRob Herring <robh@kernel.org>
Acked-by: default avatarGerd Hoffmann <kraxel@redhat.com>
Reviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20191024191859.31700-1-robh@kernel.org
parent 9e62b885

drivers/gpu/drm/drm_gem.c

+3 −0
Original line number Diff line number Diff line
@@ -1106,6 +1106,9 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size, 
		return -EINVAL;



	if (obj->funcs && obj->funcs->mmap) {

		/* Remove the fake offset */

		vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);



		ret = obj->funcs->mmap(obj, vma);

		if (ret)

			return ret;

drivers/gpu/drm/drm_gem_shmem_helper.c

+0 −3
Original line number Diff line number Diff line
@@ -541,9 +541,6 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) 
	vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);

	vma->vm_ops = &drm_gem_shmem_vm_ops;



	/* Remove the fake offset */

	vma->vm_pgoff -= drm_vma_node_start(&shmem->base.vma_node);



	return 0;

}

EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);

drivers/gpu/drm/ttm/ttm_bo_vm.c

+7 −0
Original line number Diff line number Diff line
@@ -480,6 +480,13 @@ EXPORT_SYMBOL(ttm_bo_mmap); 
int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo)

{

	ttm_bo_get(bo);



	/*

	 * FIXME: &drm_gem_object_funcs.mmap is called with the fake offset

	 * removed. Add it back here until the rest of TTM works without it.

	 */

	vma->vm_pgoff += drm_vma_node_start(&bo->base.vma_node);



	ttm_bo_mmap_vma_setup(bo, vma);

	return 0;

}

include/drm/drm_gem.h

+3 −2
Original line number Diff line number Diff line
@@ -159,8 +159,9 @@ struct drm_gem_object_funcs { 
	 *

	 * The callback is used by by both drm_gem_mmap_obj() and

	 * drm_gem_prime_mmap().  When @mmap is present @vm_ops is not

	 * used, the @mmap callback must set vma->vm_ops instead.

	 *

	 * used, the @mmap callback must set vma->vm_ops instead. The @mmap

	 * callback is always called with a 0 offset. The caller will remove

	 * the fake offset as necessary.

	 */

	int (*mmap)(struct drm_gem_object *obj, struct vm_area_struct *vma);

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