i915_mm.c revision 1.2 
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	struct sgt_iter sgt;
38	resource_size_t iobase;
39};
40
41#ifdef notyet
42static int remap_pfn(pte_t *pte, unsigned long addr, void *data)
43{
44	struct remap_pfn *r = data;
45
46	/* Special PTE are not associated with any struct vm_page */
47	set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
48	r->pfn++;
49
50	return 0;
51}
52#endif
53
54#define use_dma(io) ((io) != -1)
55
56static inline unsigned long sgt_pfn(const struct remap_pfn *r)
57{
58	if (use_dma(r->iobase))
59		return (r->sgt.dma + r->sgt.curr + r->iobase) >> PAGE_SHIFT;
60	else
61		return r->sgt.pfn + (r->sgt.curr >> PAGE_SHIFT);
62}
63
64#ifdef notyet
65
66static int remap_sg(pte_t *pte, unsigned long addr, void *data)
67{
68	struct remap_pfn *r = data;
69
70	if (GEM_WARN_ON(!r->sgt.pfn))
71		return -EINVAL;
72
73	/* Special PTE are not associated with any struct vm_page */
74	set_pte_at(r->mm, addr, pte,
75		   pte_mkspecial(pfn_pte(sgt_pfn(r), r->prot)));
76	r->pfn++; /* track insertions in case we need to unwind later */
77
78	r->sgt.curr += PAGE_SIZE;
79	if (r->sgt.curr >= r->sgt.max)
80		r->sgt = __sgt_iter(__sg_next(r->sgt.sgp), use_dma(r->iobase));
81
82	return 0;
83}
84
85/**
86 * remap_io_mapping - remap an IO mapping to userspace
87 * @vma: user vma to map to
88 * @addr: target user address to start at
89 * @pfn: physical address of kernel memory
90 * @size: size of map area
91 * @iomap: the source io_mapping
92 *
93 *  Note: this is only safe if the mm semaphore is held when called.
94 */
95int remap_io_mapping(struct vm_area_struct *vma,
96		     unsigned long addr, unsigned long pfn, unsigned long size,
97		     struct io_mapping *iomap)
98{
99	struct remap_pfn r;
100	int err;
101
102#define EXPECTED_FLAGS (VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)
103	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
104
105	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
106	r.mm = vma->vm_mm;
107	r.pfn = pfn;
108	r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
109			  (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
110
111	err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
112	if (unlikely(err)) {
113		zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
114		return err;
115	}
116
117	return 0;
118}
119
120/**
121 * remap_io_sg - remap an IO mapping to userspace
122 * @vma: user vma to map to
123 * @addr: target user address to start at
124 * @size: size of map area
125 * @sgl: Start sg entry
126 * @iobase: Use stored dma address offset by this address or pfn if -1
127 *
128 *  Note: this is only safe if the mm semaphore is held when called.
129 */
130int remap_io_sg(struct vm_area_struct *vma,
131		unsigned long addr, unsigned long size,
132		struct scatterlist *sgl, resource_size_t iobase)
133{
134	struct remap_pfn r = {
135		.mm = vma->vm_mm,
136		.prot = vma->vm_page_prot,
137		.sgt = __sgt_iter(sgl, use_dma(iobase)),
138		.iobase = iobase,
139	};
140	int err;
141
142	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
143	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
144
145	if (!use_dma(iobase))
146		flush_cache_range(vma, addr, size);
147
148	err = apply_to_page_range(r.mm, addr, size, remap_sg, &r);
149	if (unlikely(err)) {
150		zap_vma_ptes(vma, addr, r.pfn << PAGE_SHIFT);
151		return err;
152	}
153
154	return 0;
155}
156
157#endif /* notyet */
158