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 #include "i915_mm.h"
31 
32 struct 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 #define use_dma(io) ((io) != -1)
42 
sgt_pfn(const struct remap_pfn * r)43 static inline unsigned long sgt_pfn(const struct remap_pfn *r)
44 {
45 	if (use_dma(r->iobase))
46 		return (r->sgt.dma + r->sgt.curr + r->iobase) >> PAGE_SHIFT;
47 	else
48 		return r->sgt.pfn + (r->sgt.curr >> PAGE_SHIFT);
49 }
50 
remap_sg(pte_t * pte,unsigned long addr,void * data)51 static int remap_sg(pte_t *pte, unsigned long addr, void *data)
52 {
53 	struct remap_pfn *r = data;
54 
55 	if (GEM_WARN_ON(!r->sgt.sgp))
56 		return -EINVAL;
57 
58 	/* Special PTE are not associated with any struct page */
59 	set_pte_at(r->mm, addr, pte,
60 		   pte_mkspecial(pfn_pte(sgt_pfn(r), r->prot)));
61 	r->pfn++; /* track insertions in case we need to unwind later */
62 
63 	r->sgt.curr += PAGE_SIZE;
64 	if (r->sgt.curr >= r->sgt.max)
65 		r->sgt = __sgt_iter(__sg_next(r->sgt.sgp), use_dma(r->iobase));
66 
67 	return 0;
68 }
69 
70 #define EXPECTED_FLAGS (VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)
71 
72 #if IS_ENABLED(CONFIG_X86)
remap_pfn(pte_t * pte,unsigned long addr,void * data)73 static int remap_pfn(pte_t *pte, unsigned long addr, void *data)
74 {
75 	struct remap_pfn *r = data;
76 
77 	/* Special PTE are not associated with any struct page */
78 	set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
79 	r->pfn++;
80 
81 	return 0;
82 }
83 
84 /**
85  * remap_io_mapping - remap an IO mapping to userspace
86  * @vma: user vma to map to
87  * @addr: target user address to start at
88  * @pfn: physical address of kernel memory
89  * @size: size of map area
90  * @iomap: the source io_mapping
91  *
92  *  Note: this is only safe if the mm semaphore is held when called.
93  */
remap_io_mapping(struct vm_area_struct * vma,unsigned long addr,unsigned long pfn,unsigned long size,struct io_mapping * iomap)94 int remap_io_mapping(struct vm_area_struct *vma,
95 		     unsigned long addr, unsigned long pfn, unsigned long size,
96 		     struct io_mapping *iomap)
97 {
98 	struct remap_pfn r;
99 	int err;
100 
101 	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
102 
103 	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
104 	r.mm = vma->vm_mm;
105 	r.pfn = pfn;
106 	r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
107 			  (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
108 
109 	err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
110 	if (unlikely(err)) {
111 		zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
112 		return err;
113 	}
114 
115 	return 0;
116 }
117 #endif
118 
119 /**
120  * remap_io_sg - remap an IO mapping to userspace
121  * @vma: user vma to map to
122  * @addr: target user address to start at
123  * @size: size of map area
124  * @sgl: Start sg entry
125  * @iobase: Use stored dma address offset by this address or pfn if -1
126  *
127  *  Note: this is only safe if the mm semaphore is held when called.
128  */
remap_io_sg(struct vm_area_struct * vma,unsigned long addr,unsigned long size,struct scatterlist * sgl,resource_size_t iobase)129 int remap_io_sg(struct vm_area_struct *vma,
130 		unsigned long addr, unsigned long size,
131 		struct scatterlist *sgl, resource_size_t iobase)
132 {
133 	struct remap_pfn r = {
134 		.mm = vma->vm_mm,
135 		.prot = vma->vm_page_prot,
136 		.sgt = __sgt_iter(sgl, use_dma(iobase)),
137 		.iobase = iobase,
138 	};
139 	int err;
140 
141 	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
142 	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
143 
144 	if (!use_dma(iobase))
145 		flush_cache_range(vma, addr, size);
146 
147 	err = apply_to_page_range(r.mm, addr, size, remap_sg, &r);
148 	if (unlikely(err)) {
149 		zap_vma_ptes(vma, addr, r.pfn << PAGE_SHIFT);
150 		return err;
151 	}
152 
153 	return 0;
154 }
155