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      1 /*	$NetBSD: drm_gem_vm.c,v 1.15 2022/07/06 01:12:45 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 1.15 2022/07/06 01:12:45 riastradh Exp $");
     34 
     35 #include <sys/types.h>
     36 #include <sys/file.h>
     37 #include <sys/mman.h>
     38 
     39 #include <uvm/uvm_extern.h>
     40 
     41 #include <drm/drm_drv.h>
     42 #include <drm/drm_gem.h>
     43 #include <drm/drm_legacy.h>
     44 #include <drm/drm_vma_manager.h>
     45 
     46 static int	drm_gem_mmap_object_locked(struct drm_device *, off_t, size_t,
     47 		    int, struct uvm_object **, voff_t *, struct file *);
     48 
     49 void
     50 drm_gem_pager_reference(struct uvm_object *uobj)
     51 {
     52 	struct drm_gem_object *const obj = container_of(uobj,
     53 	    struct drm_gem_object, gemo_uvmobj);
     54 
     55 	drm_gem_object_get(obj);
     56 }
     57 
     58 void
     59 drm_gem_pager_detach(struct uvm_object *uobj)
     60 {
     61 	struct drm_gem_object *const obj = container_of(uobj,
     62 	    struct drm_gem_object, gemo_uvmobj);
     63 
     64 	drm_gem_object_put_unlocked(obj);
     65 }
     66 
     67 int
     68 drm_gem_or_legacy_mmap_object(struct drm_device *dev, off_t byte_offset,
     69     size_t nbytes, int prot, struct uvm_object **uobjp, voff_t *uoffsetp,
     70     struct file *file)
     71 {
     72 	int ret;
     73 
     74 	KASSERT(nbytes > 0);
     75 
     76 	ret = drm_gem_mmap_object(dev, byte_offset, nbytes, prot, uobjp,
     77 	    uoffsetp, file);
     78 	if (ret)
     79 		return ret;
     80 	if (*uobjp != NULL)
     81 		return 0;
     82 
     83 	return drm_legacy_mmap_object(dev, byte_offset, nbytes, prot, uobjp,
     84 	    uoffsetp, file);
     85 }
     86 
     87 int
     88 drm_gem_mmap_object(struct drm_device *dev, off_t byte_offset, size_t nbytes,
     89     int prot, struct uvm_object **uobjp, voff_t *uoffsetp, struct file *file)
     90 {
     91 	int ret;
     92 
     93 	KASSERT(nbytes > 0);
     94 
     95 	mutex_lock(&dev->struct_mutex);
     96 	ret = drm_gem_mmap_object_locked(dev, byte_offset, nbytes, prot,
     97 	    uobjp, uoffsetp, file);
     98 	mutex_unlock(&dev->struct_mutex);
     99 
    100 	return ret;
    101 }
    102 
    103 static int
    104 drm_gem_mmap_object_locked(struct drm_device *dev, off_t byte_offset,
    105     size_t nbytes, int prot __unused, struct uvm_object **uobjp,
    106     voff_t *uoffsetp, struct file *fp)
    107 {
    108 	struct drm_file *file = fp->f_data;
    109 	const unsigned long startpage = (byte_offset >> PAGE_SHIFT);
    110 	const unsigned long npages = (nbytes >> PAGE_SHIFT);
    111 
    112 	KASSERT(mutex_is_locked(&dev->struct_mutex));
    113 	KASSERT(drm_core_check_feature(dev, DRIVER_GEM));
    114 	KASSERT(dev->driver->gem_uvm_ops != NULL);
    115 	KASSERT(prot == (prot & (PROT_READ | PROT_WRITE)));
    116 	KASSERT(0 <= byte_offset);
    117 	KASSERT(byte_offset == (byte_offset & ~(PAGE_SIZE-1)));
    118 	KASSERT(nbytes == (npages << PAGE_SHIFT));
    119 
    120 	struct drm_vma_offset_node *const node =
    121 	    drm_vma_offset_exact_lookup(dev->vma_offset_manager, startpage,
    122 		npages);
    123 	if (node == NULL) {
    124 		/* Fall back to vanilla device mappings.  */
    125 		*uobjp = NULL;
    126 		*uoffsetp = (voff_t)-1;
    127 		return 0;
    128 	}
    129 
    130 	if (!drm_vma_node_is_allowed(node, file))
    131 		return -EACCES;
    132 
    133 	struct drm_gem_object *const obj = container_of(node,
    134 	    struct drm_gem_object, vma_node);
    135 	KASSERT(obj->dev == dev);
    136 
    137 	/* Success!  */
    138 	drm_gem_object_get(obj);
    139 	*uobjp = &obj->gemo_uvmobj;
    140 	*uoffsetp = 0;
    141 	return 0;
    142 }
    143