sys/dev/drm/linux_shmem.c

   1 /*-
   2  * Copyright (c) 2011 The FreeBSD Foundation
   3  * Copyright (c) 2014-2020 François Tigeot <ftigeot@wolfpond.org>
   4  * All rights reserved.
   5  *
   6  * Portions of this software were developed by Konstantin Belousov
   7  * under sponsorship from the FreeBSD Foundation.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  *
  30  */
  31
  32 #include <vm/vm.h>
  33 #include <vm/vm_page.h>
  34 #include <vm/vm_page2.h>
  35 #include <vm/vm_pager.h>
  36
  37 #include <linux/err.h>
  38 #include <linux/shmem_fs.h>
  39
  40 /*
  41  * This code is typically called with a normal VM object to access
  42  * data from a userspace shared memory mapping.  However, handle the
  43  * case where it might be called with OBJT_MGTDEVICE anyway.
  44  */
  45 struct page *
  46 shmem_read_mapping_page(vm_object_t object, vm_pindex_t pindex)
  47 {
  48         vm_page_t m;
  49         int rv;
  50
  51         VM_OBJECT_LOCK(object);
  52         if (object->type == OBJT_MGTDEVICE) {
  53                 m = NULL;
  54                 rv = vm_pager_get_page(object, pindex, &m, 1);
  55                 if (m == NULL)
  56                         return ERR_PTR(-ENOMEM);
  57                 if (rv != VM_PAGER_OK) {
  58                         vm_page_free(m);
  59                         return ERR_PTR(-ENOMEM);
  60                 }
  61         } else {
  62                 m = vm_page_grab(object, pindex,
  63                                  VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
  64                 if (m->valid != VM_PAGE_BITS_ALL) {
  65                         if (vm_pager_has_page(object, pindex)) {
  66                                 rv = vm_pager_get_page(object, pindex, &m, 1);
  67                                 m = vm_page_lookup(object, pindex);
  68                                 if (m == NULL)
  69                                         return ERR_PTR(-ENOMEM);
  70                                 if (rv != VM_PAGER_OK) {
  71                                         vm_page_free(m);
  72                                         return ERR_PTR(-ENOMEM);
  73                                 }
  74                         } else {
  75                                 pmap_zero_page(VM_PAGE_TO_PHYS(m));
  76                                 m->valid = VM_PAGE_BITS_ALL;
  77                                 m->dirty = 0;
  78                         }
  79                 }
  80         }
  81         vm_page_wire(m);                /* put_page() undoes this */
  82         vm_page_wakeup(m);
  83         VM_OBJECT_UNLOCK(object);
  84
  85         return (struct page *)m;
  86 }
  87
  88 struct page *
  89 shmem_read_mapping_page_gfp(struct vm_object *mapping,
  90     pgoff_t index, gfp_t gfp_mask)
  91 {
  92         return shmem_read_mapping_page(mapping, index);
  93 }