drivers/gpu/drm/i915/i915_mm.c

   1 /*
   2  * Copyright © 2014 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  */
  24
  25 #include <linux/mm.h>
  26 #include <linux/io-mapping.h>
  27
  28 #include <asm/pgtable.h>
  29
  30 #include "i915_drv.h"
  31
  32 struct remap_pfn {
  33         struct mm_struct *mm;
  34         unsigned long pfn;
  35         pgprot_t prot;
  36 };
  37
  38 static int remap_pfn(pte_t *pte, pgtable_t token,
  39                      unsigned long addr, void *data)
  40 {
  41         struct remap_pfn *r = data;
  42
  43         /* Special PTE are not associated with any struct page */
  44         set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
  45         r->pfn++;
  46
  47         return 0;
  48 }
  49
  50 /**
  51  * remap_io_mapping - remap an IO mapping to userspace
  52  * @vma: user vma to map to
  53  * @addr: target user address to start at
  54  * @pfn: physical address of kernel memory
  55  * @size: size of map area
  56  * @iomap: the source io_mapping
  57  *
  58  *  Note: this is only safe if the mm semaphore is held when called.
  59  */
  60 int remap_io_mapping(struct vm_area_struct *vma,
  61                      unsigned long addr, unsigned long pfn, unsigned long size,
  62                      struct io_mapping *iomap)
  63 {
  64         struct remap_pfn r;
  65         int err;
  66
  67         GEM_BUG_ON((vma->vm_flags &
  68                     (VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)) !=
  69                    (VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP));
  70
  71         /* We rely on prevalidation of the io-mapping to skip track_pfn(). */
  72         r.mm = vma->vm_mm;
  73         r.pfn = pfn;
  74         r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
  75                           (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
  76
  77         err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
  78         if (unlikely(err)) {
  79                 zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
  80                 return err;
  81         }
  82
  83         return 0;
  84 }