LXR linux/drivers/gpu/drm/i915/i915

   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
  32struct remap_pfn {
  33        struct mm_struct *mm;
  34        unsigned long pfn;
  35        pgprot_t prot;
  36};
  37
  38static int remap_pfn(pte_t *pte, unsigned long addr, void *data)
  39{
  40        struct remap_pfn *r = data;
  41
  42        /* Special PTE are not associated with any struct page */
  43        set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
  44        r->pfn++;
  45
  46        return 0;
  47}
  48
  49/**
  50 * remap_io_mapping - remap an IO mapping to userspace
  51 * @vma: user vma to map to
  52 * @addr: target user address to start at
  53 * @pfn: physical address of kernel memory
  54 * @size: size of map area
  55 * @iomap: the source io_mapping
  56 *
  57 *  Note: this is only safe if the mm semaphore is held when called.
  58 */
  59int remap_io_mapping(struct vm_area_struct *vma,
  60                     unsigned long addr, unsigned long pfn, unsigned long size,
  61                     struct io_mapping *iomap)
  62{
  63        struct remap_pfn r;
  64        int err;
  65
  66        GEM_BUG_ON((vma->vm_flags &
  67                    (VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)) !=
  68                   (VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP));
  69
  70        /* We rely on prevalidation of the io-mapping to skip track_pfn(). */
  71        r.mm = vma->vm_mm;
  72        r.pfn = pfn;
  73        r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
  74                          (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
  75
  76        err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
  77        if (unlikely(err)) {
  78                zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
  79                return err;
  80        }
  81
  82        return 0;
  83}
  84