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#define EXPECTED_FLAGS (VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)
67	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
68
69	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
70	r.mm = vma->vm_mm;
71	r.pfn = pfn;
72	r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
73			  (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
74
75	err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
76	if (unlikely(err)) {
77		zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
78		return err;
79	}
80
81	return 0;
82}