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drm_gem_vm.c revision 1.12 
      1 /*	$NetBSD: drm_gem_vm.c,v 1.12 2021/12/19 09:49:08 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2013 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Taylor R. Campbell.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __KERNEL_RCSID(0, "$NetBSD: drm_gem_vm.c,v 1.12 2021/12/19 09:49:08 riastradh Exp $");
     34 
     35 #include <sys/types.h>
     36 #include <sys/file.h>
     37 
     38 #include <uvm/uvm_extern.h>
     39 
     40 #include <drm/drmP.h>
     41 #include <drm/drm_gem.h>
     42 #include <drm/drm_legacy.h>
     43 #include <drm/drm_vma_manager.h>
     44 
     45 static int	drm_gem_mmap_object_locked(struct drm_device *, off_t, size_t,
     46 		    int, struct uvm_object **, voff_t *, struct file *);
     47 
     48 void
     49 drm_gem_pager_reference(struct uvm_object *uobj)
     50 {
     51 	struct drm_gem_object *const obj = container_of(uobj,
     52 	    struct drm_gem_object, gemo_uvmobj);
     53 
     54 	drm_gem_object_get(obj);
     55 }
     56 
     57 void
     58 drm_gem_pager_detach(struct uvm_object *uobj)
     59 {
     60 	struct drm_gem_object *const obj = container_of(uobj,
     61 	    struct drm_gem_object, gemo_uvmobj);
     62 
     63 	drm_gem_object_put_unlocked(obj);
     64 }
     65 
     66 int
     67 drm_gem_or_legacy_mmap_object(struct drm_device *dev, off_t byte_offset,
     68     size_t nbytes, int prot, struct uvm_object **uobjp, voff_t *uoffsetp,
     69     struct file *file)
     70 {
     71 	int ret;
     72 
     73 	ret = drm_gem_mmap_object(dev, byte_offset, nbytes, prot, uobjp,
     74 	    uoffsetp, file);
     75 	if (ret)
     76 		return ret;
     77 	if (*uobjp != NULL)
     78 		return 0;
     79 
     80 	return drm_legacy_mmap_object(dev, byte_offset, nbytes, prot, uobjp,
     81 	    uoffsetp, file);
     82 }
     83 
     84 int
     85 drm_gem_mmap_object(struct drm_device *dev, off_t byte_offset, size_t nbytes,
     86     int prot, struct uvm_object **uobjp, voff_t *uoffsetp, struct file *file)
     87 {
     88 	int ret;
     89 
     90 	mutex_lock(&dev->struct_mutex);
     91 	ret = drm_gem_mmap_object_locked(dev, byte_offset, nbytes, prot,
     92 	    uobjp, uoffsetp, file);
     93 	mutex_unlock(&dev->struct_mutex);
     94 
     95 	return ret;
     96 }
     97 
     98 static int
     99 drm_gem_mmap_object_locked(struct drm_device *dev, off_t byte_offset,
    100     size_t nbytes, int prot __unused, struct uvm_object **uobjp,
    101     voff_t *uoffsetp, struct file *fp)
    102 {
    103 	struct drm_file *file = fp->f_data;
    104 	const unsigned long startpage = (byte_offset >> PAGE_SHIFT);
    105 	const unsigned long npages = (nbytes >> PAGE_SHIFT);
    106 
    107 	KASSERT(mutex_is_locked(&dev->struct_mutex));
    108 	KASSERT(drm_core_check_feature(dev, DRIVER_GEM));
    109 	KASSERT(dev->driver->gem_uvm_ops != NULL);
    110 	KASSERT(prot == (prot & (PROT_READ | PROT_WRITE)));
    111 	KASSERT(0 <= byte_offset);
    112 	KASSERT(byte_offset == (byte_offset & ~(PAGE_SIZE-1)));
    113 	KASSERT(nbytes == (npages << PAGE_SHIFT));
    114 
    115 	struct drm_vma_offset_node *const node =
    116 	    drm_vma_offset_exact_lookup(dev->vma_offset_manager, startpage,
    117 		npages);
    118 	if (node == NULL) {
    119 		/* Fall back to vanilla device mappings.  */
    120 		*uobjp = NULL;
    121 		*uoffsetp = (voff_t)-1;
    122 		return 0;
    123 	}
    124 
    125 	if (!drm_vma_node_is_allowed(node, file))
    126 		return -EACCES;
    127 
    128 	struct drm_gem_object *const obj = container_of(node,
    129 	    struct drm_gem_object, vma_node);
    130 	KASSERT(obj->dev == dev);
    131 
    132 	/* Success!  */
    133 	drm_gem_object_get(obj);
    134 	*uobjp = &obj->gemo_uvmobj;
    135 	*uoffsetp = 0;
    136 	return 0;
    137 }
    138