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1 | // SPDX-License-Identifier: GPL-2.0 | |
2 | /* | |
3 | * linux/arch/arm/mm/mmap.c | |
4 | */ | |
5 | #include <linux/fs.h> | |
6 | #include <linux/mm.h> | |
7 | #include <linux/mman.h> | |
8 | #include <linux/shm.h> | |
9 | #include <linux/sched/signal.h> | |
10 | #include <linux/sched/mm.h> | |
11 | #include <linux/io.h> | |
12 | #include <linux/personality.h> | |
13 | #include <linux/random.h> | |
14 | #include <asm/cachetype.h> | |
15 | ||
16 | #define COLOUR_ALIGN(addr,pgoff) \ | |
17 | ((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \ | |
18 | (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1))) | |
19 | ||
20 | /* | |
21 | * We need to ensure that shared mappings are correctly aligned to | |
22 | * avoid aliasing issues with VIPT caches. We need to ensure that | |
23 | * a specific page of an object is always mapped at a multiple of | |
24 | * SHMLBA bytes. | |
25 | * | |
26 | * We unconditionally provide this function for all cases, however | |
27 | * in the VIVT case, we optimise out the alignment rules. | |
28 | */ | |
29 | unsigned long | |
30 | arch_get_unmapped_area(struct file *filp, unsigned long addr, | |
31 | unsigned long len, unsigned long pgoff, unsigned long flags) | |
32 | { | |
33 | struct mm_struct *mm = current->mm; | |
34 | struct vm_area_struct *vma; | |
35 | int do_align = 0; | |
36 | int aliasing = cache_is_vipt_aliasing(); | |
37 | struct vm_unmapped_area_info info; | |
38 | ||
39 | /* | |
40 | * We only need to do colour alignment if either the I or D | |
41 | * caches alias. | |
42 | */ | |
43 | if (aliasing) | |
44 | do_align = filp || (flags & MAP_SHARED); | |
45 | ||
46 | /* | |
47 | * We enforce the MAP_FIXED case. | |
48 | */ | |
49 | if (flags & MAP_FIXED) { | |
50 | if (aliasing && flags & MAP_SHARED && | |
51 | (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)) | |
52 | return -EINVAL; | |
53 | return addr; | |
54 | } | |
55 | ||
56 | if (len > TASK_SIZE) | |
57 | return -ENOMEM; | |
58 | ||
59 | if (addr) { | |
60 | if (do_align) | |
61 | addr = COLOUR_ALIGN(addr, pgoff); | |
62 | else | |
63 | addr = PAGE_ALIGN(addr); | |
64 | ||
65 | vma = find_vma(mm, addr); | |
66 | if (TASK_SIZE - len >= addr && | |
67 | (!vma || addr + len <= vm_start_gap(vma))) | |
68 | return addr; | |
69 | } | |
70 | ||
71 | info.flags = 0; | |
72 | info.length = len; | |
73 | info.low_limit = mm->mmap_base; | |
74 | info.high_limit = TASK_SIZE; | |
75 | info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0; | |
76 | info.align_offset = pgoff << PAGE_SHIFT; | |
77 | return vm_unmapped_area(&info); | |
78 | } | |
79 | ||
80 | unsigned long | |
81 | arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, | |
82 | const unsigned long len, const unsigned long pgoff, | |
83 | const unsigned long flags) | |
84 | { | |
85 | struct vm_area_struct *vma; | |
86 | struct mm_struct *mm = current->mm; | |
87 | unsigned long addr = addr0; | |
88 | int do_align = 0; | |
89 | int aliasing = cache_is_vipt_aliasing(); | |
90 | struct vm_unmapped_area_info info; | |
91 | ||
92 | /* | |
93 | * We only need to do colour alignment if either the I or D | |
94 | * caches alias. | |
95 | */ | |
96 | if (aliasing) | |
97 | do_align = filp || (flags & MAP_SHARED); | |
98 | ||
99 | /* requested length too big for entire address space */ | |
100 | if (len > TASK_SIZE) | |
101 | return -ENOMEM; | |
102 | ||
103 | if (flags & MAP_FIXED) { | |
104 | if (aliasing && flags & MAP_SHARED && | |
105 | (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)) | |
106 | return -EINVAL; | |
107 | return addr; | |
108 | } | |
109 | ||
110 | /* requesting a specific address */ | |
111 | if (addr) { | |
112 | if (do_align) | |
113 | addr = COLOUR_ALIGN(addr, pgoff); | |
114 | else | |
115 | addr = PAGE_ALIGN(addr); | |
116 | vma = find_vma(mm, addr); | |
117 | if (TASK_SIZE - len >= addr && | |
118 | (!vma || addr + len <= vm_start_gap(vma))) | |
119 | return addr; | |
120 | } | |
121 | ||
122 | info.flags = VM_UNMAPPED_AREA_TOPDOWN; | |
123 | info.length = len; | |
124 | info.low_limit = FIRST_USER_ADDRESS; | |
125 | info.high_limit = mm->mmap_base; | |
126 | info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0; | |
127 | info.align_offset = pgoff << PAGE_SHIFT; | |
128 | addr = vm_unmapped_area(&info); | |
129 | ||
130 | /* | |
131 | * A failed mmap() very likely causes application failure, | |
132 | * so fall back to the bottom-up function here. This scenario | |
133 | * can happen with large stack limits and large mmap() | |
134 | * allocations. | |
135 | */ | |
136 | if (addr & ~PAGE_MASK) { | |
137 | VM_BUG_ON(addr != -ENOMEM); | |
138 | info.flags = 0; | |
139 | info.low_limit = mm->mmap_base; | |
140 | info.high_limit = TASK_SIZE; | |
141 | addr = vm_unmapped_area(&info); | |
142 | } | |
143 | ||
144 | return addr; | |
145 | } | |
146 | ||
147 | /* | |
148 | * You really shouldn't be using read() or write() on /dev/mem. This | |
149 | * might go away in the future. | |
150 | */ | |
151 | int valid_phys_addr_range(phys_addr_t addr, size_t size) | |
152 | { | |
153 | if (addr < PHYS_OFFSET) | |
154 | return 0; | |
155 | if (addr + size > __pa(high_memory - 1) + 1) | |
156 | return 0; | |
157 | ||
158 | return 1; | |
159 | } | |
160 | ||
161 | /* | |
162 | * Do not allow /dev/mem mappings beyond the supported physical range. | |
163 | */ | |
164 | int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) | |
165 | { | |
166 | return (pfn + (size >> PAGE_SHIFT)) <= (1 + (PHYS_MASK >> PAGE_SHIFT)); | |
167 | } | |
168 | ||
169 | #ifdef CONFIG_STRICT_DEVMEM | |
170 | ||
171 | #include <linux/ioport.h> | |
172 | ||
173 | /* | |
174 | * devmem_is_allowed() checks to see if /dev/mem access to a certain | |
175 | * address is valid. The argument is a physical page number. | |
176 | * We mimic x86 here by disallowing access to system RAM as well as | |
177 | * device-exclusive MMIO regions. This effectively disable read()/write() | |
178 | * on /dev/mem. | |
179 | */ | |
180 | int devmem_is_allowed(unsigned long pfn) | |
181 | { | |
182 | if (iomem_is_exclusive(pfn << PAGE_SHIFT)) | |
183 | return 0; | |
184 | if (!page_is_ram(pfn)) | |
185 | return 1; | |
186 | return 0; | |
187 | } | |
188 | ||
189 | #endif |