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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 | /* gap between mmap and stack */ | |
21 | #define MIN_GAP (128*1024*1024UL) | |
22 | #define MAX_GAP ((TASK_SIZE)/6*5) | |
23 | ||
24 | static int mmap_is_legacy(void) | |
25 | { | |
26 | if (current->personality & ADDR_COMPAT_LAYOUT) | |
27 | return 1; | |
28 | ||
29 | if (rlimit(RLIMIT_STACK) == RLIM_INFINITY) | |
30 | return 1; | |
31 | ||
32 | return sysctl_legacy_va_layout; | |
33 | } | |
34 | ||
35 | static unsigned long mmap_base(unsigned long rnd) | |
36 | { | |
37 | unsigned long gap = rlimit(RLIMIT_STACK); | |
38 | ||
39 | if (gap < MIN_GAP) | |
40 | gap = MIN_GAP; | |
41 | else if (gap > MAX_GAP) | |
42 | gap = MAX_GAP; | |
43 | ||
44 | return PAGE_ALIGN(TASK_SIZE - gap - rnd); | |
45 | } | |
46 | ||
47 | /* | |
48 | * We need to ensure that shared mappings are correctly aligned to | |
49 | * avoid aliasing issues with VIPT caches. We need to ensure that | |
50 | * a specific page of an object is always mapped at a multiple of | |
51 | * SHMLBA bytes. | |
52 | * | |
53 | * We unconditionally provide this function for all cases, however | |
54 | * in the VIVT case, we optimise out the alignment rules. | |
55 | */ | |
56 | unsigned long | |
57 | arch_get_unmapped_area(struct file *filp, unsigned long addr, | |
58 | unsigned long len, unsigned long pgoff, unsigned long flags) | |
59 | { | |
60 | struct mm_struct *mm = current->mm; | |
61 | struct vm_area_struct *vma; | |
62 | int do_align = 0; | |
63 | int aliasing = cache_is_vipt_aliasing(); | |
64 | struct vm_unmapped_area_info info; | |
65 | ||
66 | /* | |
67 | * We only need to do colour alignment if either the I or D | |
68 | * caches alias. | |
69 | */ | |
70 | if (aliasing) | |
71 | do_align = filp || (flags & MAP_SHARED); | |
72 | ||
73 | /* | |
74 | * We enforce the MAP_FIXED case. | |
75 | */ | |
76 | if (flags & MAP_FIXED) { | |
77 | if (aliasing && flags & MAP_SHARED && | |
78 | (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)) | |
79 | return -EINVAL; | |
80 | return addr; | |
81 | } | |
82 | ||
83 | if (len > TASK_SIZE) | |
84 | return -ENOMEM; | |
85 | ||
86 | if (addr) { | |
87 | if (do_align) | |
88 | addr = COLOUR_ALIGN(addr, pgoff); | |
89 | else | |
90 | addr = PAGE_ALIGN(addr); | |
91 | ||
92 | vma = find_vma(mm, addr); | |
93 | if (TASK_SIZE - len >= addr && | |
94 | (!vma || addr + len <= vm_start_gap(vma))) | |
95 | return addr; | |
96 | } | |
97 | ||
98 | info.flags = 0; | |
99 | info.length = len; | |
100 | info.low_limit = mm->mmap_base; | |
101 | info.high_limit = TASK_SIZE; | |
102 | info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0; | |
103 | info.align_offset = pgoff << PAGE_SHIFT; | |
104 | return vm_unmapped_area(&info); | |
105 | } | |
106 | ||
107 | unsigned long | |
108 | arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, | |
109 | const unsigned long len, const unsigned long pgoff, | |
110 | const unsigned long flags) | |
111 | { | |
112 | struct vm_area_struct *vma; | |
113 | struct mm_struct *mm = current->mm; | |
114 | unsigned long addr = addr0; | |
115 | int do_align = 0; | |
116 | int aliasing = cache_is_vipt_aliasing(); | |
117 | struct vm_unmapped_area_info info; | |
118 | ||
119 | /* | |
120 | * We only need to do colour alignment if either the I or D | |
121 | * caches alias. | |
122 | */ | |
123 | if (aliasing) | |
124 | do_align = filp || (flags & MAP_SHARED); | |
125 | ||
126 | /* requested length too big for entire address space */ | |
127 | if (len > TASK_SIZE) | |
128 | return -ENOMEM; | |
129 | ||
130 | if (flags & MAP_FIXED) { | |
131 | if (aliasing && flags & MAP_SHARED && | |
132 | (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)) | |
133 | return -EINVAL; | |
134 | return addr; | |
135 | } | |
136 | ||
137 | /* requesting a specific address */ | |
138 | if (addr) { | |
139 | if (do_align) | |
140 | addr = COLOUR_ALIGN(addr, pgoff); | |
141 | else | |
142 | addr = PAGE_ALIGN(addr); | |
143 | vma = find_vma(mm, addr); | |
144 | if (TASK_SIZE - len >= addr && | |
145 | (!vma || addr + len <= vm_start_gap(vma))) | |
146 | return addr; | |
147 | } | |
148 | ||
149 | info.flags = VM_UNMAPPED_AREA_TOPDOWN; | |
150 | info.length = len; | |
151 | info.low_limit = FIRST_USER_ADDRESS; | |
152 | info.high_limit = mm->mmap_base; | |
153 | info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0; | |
154 | info.align_offset = pgoff << PAGE_SHIFT; | |
155 | addr = vm_unmapped_area(&info); | |
156 | ||
157 | /* | |
158 | * A failed mmap() very likely causes application failure, | |
159 | * so fall back to the bottom-up function here. This scenario | |
160 | * can happen with large stack limits and large mmap() | |
161 | * allocations. | |
162 | */ | |
163 | if (addr & ~PAGE_MASK) { | |
164 | VM_BUG_ON(addr != -ENOMEM); | |
165 | info.flags = 0; | |
166 | info.low_limit = mm->mmap_base; | |
167 | info.high_limit = TASK_SIZE; | |
168 | addr = vm_unmapped_area(&info); | |
169 | } | |
170 | ||
171 | return addr; | |
172 | } | |
173 | ||
174 | unsigned long arch_mmap_rnd(void) | |
175 | { | |
176 | unsigned long rnd; | |
177 | ||
178 | rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); | |
179 | ||
180 | return rnd << PAGE_SHIFT; | |
181 | } | |
182 | ||
183 | void arch_pick_mmap_layout(struct mm_struct *mm) | |
184 | { | |
185 | unsigned long random_factor = 0UL; | |
186 | ||
187 | if (current->flags & PF_RANDOMIZE) | |
188 | random_factor = arch_mmap_rnd(); | |
189 | ||
190 | if (mmap_is_legacy()) { | |
191 | mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; | |
192 | mm->get_unmapped_area = arch_get_unmapped_area; | |
193 | } else { | |
194 | mm->mmap_base = mmap_base(random_factor); | |
195 | mm->get_unmapped_area = arch_get_unmapped_area_topdown; | |
196 | } | |
197 | } | |
198 | ||
199 | /* | |
200 | * You really shouldn't be using read() or write() on /dev/mem. This | |
201 | * might go away in the future. | |
202 | */ | |
203 | int valid_phys_addr_range(phys_addr_t addr, size_t size) | |
204 | { | |
205 | if (addr < PHYS_OFFSET) | |
206 | return 0; | |
207 | if (addr + size > __pa(high_memory - 1) + 1) | |
208 | return 0; | |
209 | ||
210 | return 1; | |
211 | } | |
212 | ||
213 | /* | |
214 | * Do not allow /dev/mem mappings beyond the supported physical range. | |
215 | */ | |
216 | int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) | |
217 | { | |
218 | return (pfn + (size >> PAGE_SHIFT)) <= (1 + (PHYS_MASK >> PAGE_SHIFT)); | |
219 | } | |
220 | ||
221 | #ifdef CONFIG_STRICT_DEVMEM | |
222 | ||
223 | #include <linux/ioport.h> | |
224 | ||
225 | /* | |
226 | * devmem_is_allowed() checks to see if /dev/mem access to a certain | |
227 | * address is valid. The argument is a physical page number. | |
228 | * We mimic x86 here by disallowing access to system RAM as well as | |
229 | * device-exclusive MMIO regions. This effectively disable read()/write() | |
230 | * on /dev/mem. | |
231 | */ | |
232 | int devmem_is_allowed(unsigned long pfn) | |
233 | { | |
234 | if (iomem_is_exclusive(pfn << PAGE_SHIFT)) | |
235 | return 0; | |
236 | if (!page_is_ram(pfn)) | |
237 | return 1; | |
238 | return 0; | |
239 | } | |
240 | ||
241 | #endif |