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1/*
2 * linux/arch/arm/mm/mmap.c
3 */
4#include <linux/fs.h>
5#include <linux/mm.h>
6#include <linux/mman.h>
7#include <linux/shm.h>
8#include <linux/sched.h>
9#include <linux/io.h>
10#include <linux/personality.h>
11#include <linux/random.h>
12#include <asm/cachetype.h>
13
14#define COLOUR_ALIGN(addr,pgoff) \
15 ((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \
16 (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
17
18/* gap between mmap and stack */
19#define MIN_GAP (128*1024*1024UL)
20#define MAX_GAP ((TASK_SIZE)/6*5)
21
22static int mmap_is_legacy(void)
23{
24 if (current->personality & ADDR_COMPAT_LAYOUT)
25 return 1;
26
27 if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
28 return 1;
29
30 return sysctl_legacy_va_layout;
31}
32
33static unsigned long mmap_base(unsigned long rnd)
34{
35 unsigned long gap = rlimit(RLIMIT_STACK);
36
37 if (gap < MIN_GAP)
38 gap = MIN_GAP;
39 else if (gap > MAX_GAP)
40 gap = MAX_GAP;
41
42 return PAGE_ALIGN(TASK_SIZE - gap - rnd);
43}
44
45/*
46 * We need to ensure that shared mappings are correctly aligned to
47 * avoid aliasing issues with VIPT caches. We need to ensure that
48 * a specific page of an object is always mapped at a multiple of
49 * SHMLBA bytes.
50 *
51 * We unconditionally provide this function for all cases, however
52 * in the VIVT case, we optimise out the alignment rules.
53 */
54unsigned long
55arch_get_unmapped_area(struct file *filp, unsigned long addr,
56 unsigned long len, unsigned long pgoff, unsigned long flags)
57{
58 struct mm_struct *mm = current->mm;
59 struct vm_area_struct *vma;
60 int do_align = 0;
61 int aliasing = cache_is_vipt_aliasing();
62 struct vm_unmapped_area_info info;
63
64 /*
65 * We only need to do colour alignment if either the I or D
66 * caches alias.
67 */
68 if (aliasing)
69 do_align = filp || (flags & MAP_SHARED);
70
71 /*
72 * We enforce the MAP_FIXED case.
73 */
74 if (flags & MAP_FIXED) {
75 if (aliasing && flags & MAP_SHARED &&
76 (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
77 return -EINVAL;
78 return addr;
79 }
80
81 if (len > TASK_SIZE)
82 return -ENOMEM;
83
84 if (addr) {
85 if (do_align)
86 addr = COLOUR_ALIGN(addr, pgoff);
87 else
88 addr = PAGE_ALIGN(addr);
89
90 vma = find_vma(mm, addr);
91 if (TASK_SIZE - len >= addr &&
92 (!vma || addr + len <= vma->vm_start))
93 return addr;
94 }
95
96 info.flags = 0;
97 info.length = len;
98 info.low_limit = mm->mmap_base;
99 info.high_limit = TASK_SIZE;
100 info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
101 info.align_offset = pgoff << PAGE_SHIFT;
102 return vm_unmapped_area(&info);
103}
104
105unsigned long
106arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
107 const unsigned long len, const unsigned long pgoff,
108 const unsigned long flags)
109{
110 struct vm_area_struct *vma;
111 struct mm_struct *mm = current->mm;
112 unsigned long addr = addr0;
113 int do_align = 0;
114 int aliasing = cache_is_vipt_aliasing();
115 struct vm_unmapped_area_info info;
116
117 /*
118 * We only need to do colour alignment if either the I or D
119 * caches alias.
120 */
121 if (aliasing)
122 do_align = filp || (flags & MAP_SHARED);
123
124 /* requested length too big for entire address space */
125 if (len > TASK_SIZE)
126 return -ENOMEM;
127
128 if (flags & MAP_FIXED) {
129 if (aliasing && flags & MAP_SHARED &&
130 (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
131 return -EINVAL;
132 return addr;
133 }
134
135 /* requesting a specific address */
136 if (addr) {
137 if (do_align)
138 addr = COLOUR_ALIGN(addr, pgoff);
139 else
140 addr = PAGE_ALIGN(addr);
141 vma = find_vma(mm, addr);
142 if (TASK_SIZE - len >= addr &&
143 (!vma || addr + len <= vma->vm_start))
144 return addr;
145 }
146
147 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
148 info.length = len;
149 info.low_limit = FIRST_USER_ADDRESS;
150 info.high_limit = mm->mmap_base;
151 info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
152 info.align_offset = pgoff << PAGE_SHIFT;
153 addr = vm_unmapped_area(&info);
154
155 /*
156 * A failed mmap() very likely causes application failure,
157 * so fall back to the bottom-up function here. This scenario
158 * can happen with large stack limits and large mmap()
159 * allocations.
160 */
161 if (addr & ~PAGE_MASK) {
162 VM_BUG_ON(addr != -ENOMEM);
163 info.flags = 0;
164 info.low_limit = mm->mmap_base;
165 info.high_limit = TASK_SIZE;
166 addr = vm_unmapped_area(&info);
167 }
168
169 return addr;
170}
171
172void arch_pick_mmap_layout(struct mm_struct *mm)
173{
174 unsigned long random_factor = 0UL;
175
176 /* 8 bits of randomness in 20 address space bits */
177 if ((current->flags & PF_RANDOMIZE) &&
178 !(current->personality & ADDR_NO_RANDOMIZE))
179 random_factor = (get_random_int() % (1 << 8)) << PAGE_SHIFT;
180
181 if (mmap_is_legacy()) {
182 mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
183 mm->get_unmapped_area = arch_get_unmapped_area;
184 } else {
185 mm->mmap_base = mmap_base(random_factor);
186 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
187 }
188}
189
190/*
191 * You really shouldn't be using read() or write() on /dev/mem. This
192 * might go away in the future.
193 */
194int valid_phys_addr_range(phys_addr_t addr, size_t size)
195{
196 if (addr < PHYS_OFFSET)
197 return 0;
198 if (addr + size > __pa(high_memory - 1) + 1)
199 return 0;
200
201 return 1;
202}
203
204/*
205 * Do not allow /dev/mem mappings beyond the supported physical range.
206 */
207int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
208{
209 return (pfn + (size >> PAGE_SHIFT)) <= (1 + (PHYS_MASK >> PAGE_SHIFT));
210}
211
212#ifdef CONFIG_STRICT_DEVMEM
213
214#include <linux/ioport.h>
215
216/*
217 * devmem_is_allowed() checks to see if /dev/mem access to a certain
218 * address is valid. The argument is a physical page number.
219 * We mimic x86 here by disallowing access to system RAM as well as
220 * device-exclusive MMIO regions. This effectively disable read()/write()
221 * on /dev/mem.
222 */
223int devmem_is_allowed(unsigned long pfn)
224{
225 if (iomem_is_exclusive(pfn << PAGE_SHIFT))
226 return 0;
227 if (!page_is_ram(pfn))
228 return 1;
229 return 0;
230}
231
232#endif
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 */
29unsigned long
30arch_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
80unsigned long
81arch_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 */
151int 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 */
164int 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 */
180int 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