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
29 #include "i915_drv.h"
30
31 struct remap_pfn {
32 struct mm_struct *mm;
33 unsigned long pfn;
34 pgprot_t prot;
35
36 struct sgt_iter sgt;
37 resource_size_t iobase;
38 };
39
remap_pfn(pte_t * pte,unsigned long addr,void * data)40 static int remap_pfn(pte_t *pte, unsigned long addr, void *data)
41 {
42 struct remap_pfn *r = data;
43
44 /* Special PTE are not associated with any struct page */
45 set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
46 r->pfn++;
47
48 return 0;
49 }
50
51 #define use_dma(io) ((io) != -1)
52
sgt_pfn(const struct remap_pfn * r)53 static inline unsigned long sgt_pfn(const struct remap_pfn *r)
54 {
55 if (use_dma(r->iobase))
56 return (r->sgt.dma + r->sgt.curr + r->iobase) >> PAGE_SHIFT;
57 else
58 return r->sgt.pfn + (r->sgt.curr >> PAGE_SHIFT);
59 }
60
remap_sg(pte_t * pte,unsigned long addr,void * data)61 static int remap_sg(pte_t *pte, unsigned long addr, void *data)
62 {
63 struct remap_pfn *r = data;
64
65 if (GEM_WARN_ON(!r->sgt.pfn))
66 return -EINVAL;
67
68 /* Special PTE are not associated with any struct page */
69 set_pte_at(r->mm, addr, pte,
70 pte_mkspecial(pfn_pte(sgt_pfn(r), r->prot)));
71 r->pfn++; /* track insertions in case we need to unwind later */
72
73 r->sgt.curr += PAGE_SIZE;
74 if (r->sgt.curr >= r->sgt.max)
75 r->sgt = __sgt_iter(__sg_next(r->sgt.sgp), use_dma(r->iobase));
76
77 return 0;
78 }
79
80 /**
81 * remap_io_mapping - remap an IO mapping to userspace
82 * @vma: user vma to map to
83 * @addr: target user address to start at
84 * @pfn: physical address of kernel memory
85 * @size: size of map area
86 * @iomap: the source io_mapping
87 *
88 * Note: this is only safe if the mm semaphore is held when called.
89 */
remap_io_mapping(struct vm_area_struct * vma,unsigned long addr,unsigned long pfn,unsigned long size,struct io_mapping * iomap)90 int remap_io_mapping(struct vm_area_struct *vma,
91 unsigned long addr, unsigned long pfn, unsigned long size,
92 struct io_mapping *iomap)
93 {
94 struct remap_pfn r;
95 int err;
96
97 #define EXPECTED_FLAGS (VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)
98 GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
99
100 /* We rely on prevalidation of the io-mapping to skip track_pfn(). */
101 r.mm = vma->vm_mm;
102 r.pfn = pfn;
103 r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
104 (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
105
106 err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
107 if (unlikely(err)) {
108 zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
109 return err;
110 }
111
112 return 0;
113 }
114
115 /**
116 * remap_io_sg - remap an IO mapping to userspace
117 * @vma: user vma to map to
118 * @addr: target user address to start at
119 * @size: size of map area
120 * @sgl: Start sg entry
121 * @iobase: Use stored dma address offset by this address or pfn if -1
122 *
123 * Note: this is only safe if the mm semaphore is held when called.
124 */
remap_io_sg(struct vm_area_struct * vma,unsigned long addr,unsigned long size,struct scatterlist * sgl,resource_size_t iobase)125 int remap_io_sg(struct vm_area_struct *vma,
126 unsigned long addr, unsigned long size,
127 struct scatterlist *sgl, resource_size_t iobase)
128 {
129 struct remap_pfn r = {
130 .mm = vma->vm_mm,
131 .prot = vma->vm_page_prot,
132 .sgt = __sgt_iter(sgl, use_dma(iobase)),
133 .iobase = iobase,
134 };
135 int err;
136
137 /* We rely on prevalidation of the io-mapping to skip track_pfn(). */
138 GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
139
140 if (!use_dma(iobase))
141 flush_cache_range(vma, addr, size);
142
143 err = apply_to_page_range(r.mm, addr, size, remap_sg, &r);
144 if (unlikely(err)) {
145 zap_vma_ptes(vma, addr, r.pfn << PAGE_SHIFT);
146 return err;
147 }
148
149 return 0;
150 }
151