Re: [PATCH 1/8] drm: add mmap() to drm_gem_object_funcs

On Fri, Sep 13, 2019 at 02:29:01PM +0200, Gerd Hoffmann wrote:

drm_gem_object_funcs->vm_ops alone can't handle everything which needs to be done for mmap(), tweaking vm_flags for example. So add a new mmap() callback to drm_gem_object_funcs where this code can go to.

Note that the vm_ops field is not used in case the mmap callback is presnt, it is expected that the callback sets vma->vm_ops instead.

drm_gem_mmap_obj() will use the new callback for object specific mmap setup. With this in place the need for driver-speific fops->mmap callbacks goes away, drm_gem_mmap can be hooked instead.

drm_gem_prime_mmap() will use the new callback too to just mmap gem objects directly instead of jumping though loops to make drm_gem_object_lookup() and fops->mmap work.

Signed-off-by: Gerd Hoffmann kraxel@redhat.com

include/drm/drm_gem.h | 14 ++++++++++++++ drivers/gpu/drm/drm_gem.c | 27 ++++++++++++++++++--------- drivers/gpu/drm/drm_prime.c | 9 +++++++++ 3 files changed, 41 insertions(+), 9 deletions(-)

diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index 6aaba14f5972..e71f75a2ab57 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -150,6 +150,20 @@ struct drm_gem_object_funcs { */ void (*vunmap)(struct drm_gem_object *obj, void *vaddr);

• /**

• * @mmap:
  

• *
  

• * Handle mmap() of the gem object, setup vma accordingly.
  

• *
  

• * This callback is optional.
  

• *
  

• * 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.
  

• *
  

• */
  

• int (*mmap)(struct drm_gem_object *obj, struct vm_area_struct *vma);
• /**
  • @vm_ops:

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 6854f5867d51..56f42e0f2584 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -1099,22 +1099,31 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size, struct vm_area_struct *vma) { struct drm_device *dev = obj->dev;

• int ret;

  /* Check for valid size. */ if (obj_size < vma->vm_end - vma->vm_start) return -EINVAL;

• if (obj->funcs && obj->funcs->vm_ops)

• vma->vm_ops = obj->funcs->vm_ops;
  

• else if (dev->driver->gem_vm_ops)

• vma->vm_ops = dev->driver->gem_vm_ops;
  

• else

• return -EINVAL;
  

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

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

• if (ret)
  

• 	return ret;
  

• WARN_ON(!(vma->vm_flags & VM_DONTEXPAND));
  

Yeah I think checking for VM_DONTEXPAND is even better than checking for just VM_SPECIAL.

Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch

• } else {

• if (obj->funcs && obj->funcs->vm_ops)
  

• 	vma->vm_ops = obj->funcs->vm_ops;
  

• else if (dev->driver->gem_vm_ops)
  

• 	vma->vm_ops = dev->driver->gem_vm_ops;
  

• else
  

• 	return -EINVAL;
  

• vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
  

• vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
  

• vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
  

• }

• vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; vma->vm_private_data = obj;

• vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));

• vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);

  /* Take a ref for this mapping of the object, so that the fault

  • handler can dereference the mmap offset's pointer to the object.

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 0a2316e0e812..0814211b0f3f 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -713,6 +713,15 @@ int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) struct file *fil; int ret;

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

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

• if (ret)
  

• 	return ret;
  

• vma->vm_private_data = obj;
  

• drm_gem_object_get(obj);
  

• return 0;
  

• }
• priv = kzalloc(sizeof(*priv), GFP_KERNEL); fil = kzalloc(sizeof(*fil), GFP_KERNEL); if (!priv || !fil) {

-- 2.18.1