/**
* drm_gem_mmap_obj - memory map a GEM object
* @obj: the GEM object to map
* @obj_size: the object size to be mapped, in bytes
* @vma: VMA for the area to be mapped
*
* Set up the VMA to prepare mapping of the GEM object using the gem_vm_ops
* provided by the driver. Depending on their requirements, drivers can either
* provide a fault handler in their gem_vm_ops (in which case any accesses to
* the object will be trapped, to perform migration, GTT binding, surface
* register allocation, or performance monitoring), or mmap the buffer memory
* synchronously after calling drm_gem_mmap_obj.
*
* This function is mainly intended to implement the DMABUF mmap operation, when
* the GEM object is not looked up based on its fake offset. To implement the
* DRM mmap operation, drivers should use the drm_gem_mmap() function.
*
* drm_gem_mmap_obj() assumes the user is granted access to the buffer while
* drm_gem_mmap() prevents unprivileged users from mapping random objects. So
* callers must verify access restrictions before calling this helper.
*
* NOTE: This function has to be protected with dev->struct_mutex
*
* Return 0 or success or -EINVAL if the object size is smaller than the VMA
* size, or if no gem_vm_ops are provided.
*/
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;
lockdep_assert_held(&dev->struct_mutex);
/* Check for valid size. */
if (obj_size < vma->vm_end - vma->vm_start)
return -EINVAL;
if (!dev->driver->gem_vm_ops)
return -EINVAL;
vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
vma->vm_ops = dev->driver->gem_vm_ops;
vma->vm_private_data = obj;
vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
/* Take a ref for this mapping of the object, so that the fault
* handler can dereference the mmap offset's pointer to the object.
* This reference is cleaned up by the corresponding vm_close
* (which should happen whether the vma was created by this call, or
* by a vm_open due to mremap or partial unmap or whatever).
*/
drm_gem_object_reference(obj);
drm_vm_open_locked(dev, vma);
return 0;
}
/**
* 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_local_map *map = NULL;
struct drm_gem_object *obj;
struct drm_hash_item *hash;
int ret = 0;
if (drm_device_is_unplugged(dev))
return -ENODEV;
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_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
vma->vm_ops = obj->dev->driver->gem_vm_ops;
vma->vm_private_data = map->handle;
vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
/* Take a ref for this mapping of the object, so that the fault
* handler can dereference the mmap offset's pointer to the object.
* This reference is cleaned up by the corresponding vm_close
* (which should happen whether the vma was created by this call, or
* by a vm_open due to mremap or partial unmap or whatever).
*/
drm_gem_object_reference(obj);
drm_vm_open_locked(dev, vma);
out_unlock:
mutex_unlock(&dev->struct_mutex);
return ret;
}
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_local_map *map = NULL;
struct drm_gem_object *obj;
struct drm_hash_item *hash;
int ret = 0;
if (drm_device_is_unplugged(dev))
return -ENODEV;
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;
}
/* */
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;
vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
/*
*/
drm_gem_object_reference(obj);
drm_vm_open_locked(vma);
out_unlock:
mutex_unlock(&dev->struct_mutex);
return ret;
}
void drm_gem_vm_open(struct vm_area_struct *vma)
{
struct drm_gem_object *obj = vma->vm_private_data;
drm_gem_object_reference(obj);
mutex_lock(&obj->dev->struct_mutex);
drm_vm_open_locked(vma);
mutex_unlock(&obj->dev->struct_mutex);
}
int main(void)
{
struct drm_device dev;
drm_vm_open_locked(&dev);
drm_vm_open_locked(&dev);
}
