1 /*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (C) 2011 Wind River Systems,
7 * written by Ralf Baechle <ralf@linux-mips.org>
8 */
9 #include <linux/compiler.h>
10 #include <linux/elf-randomize.h>
11 #include <linux/errno.h>
12 #include <linux/mm.h>
13 #include <linux/mman.h>
14 #include <linux/export.h>
15 #include <linux/personality.h>
16 #include <linux/random.h>
17 #include <linux/sched/signal.h>
18 #include <linux/sched/mm.h>
19
20 unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */
21 EXPORT_SYMBOL(shm_align_mask);
22
23 #define COLOUR_ALIGN(addr, pgoff) \
24 ((((addr) + shm_align_mask) & ~shm_align_mask) + \
25 (((pgoff) << PAGE_SHIFT) & shm_align_mask))
26
27 enum mmap_allocation_direction {UP, DOWN};
28
29 static unsigned long arch_get_unmapped_area_common(struct file *filp,
30 unsigned long addr0, unsigned long len, unsigned long pgoff,
31 unsigned long flags, enum mmap_allocation_direction dir)
32 {
33 struct mm_struct *mm = current->mm;
34 struct vm_area_struct *vma;
35 unsigned long addr = addr0;
36 int do_color_align;
37 struct vm_unmapped_area_info info = {};
38
39 if (unlikely(len > TASK_SIZE))
40 return -ENOMEM;
41
42 if (flags & MAP_FIXED) {
43 /* Even MAP_FIXED mappings must reside within TASK_SIZE */
44 if (TASK_SIZE - len < addr)
45 return -EINVAL;
46
47 /*
48 * We do not accept a shared mapping if it would violate
49 * cache aliasing constraints.
50 */
51 if ((flags & MAP_SHARED) &&
52 ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
53 return -EINVAL;
54 return addr;
55 }
56
57 do_color_align = 0;
58 if (filp || (flags & MAP_SHARED))
59 do_color_align = 1;
60
61 /* requesting a specific address */
62 if (addr) {
63 if (do_color_align)
64 addr = COLOUR_ALIGN(addr, pgoff);
65 else
66 addr = PAGE_ALIGN(addr);
67
68 vma = find_vma(mm, addr);
69 if (TASK_SIZE - len >= addr &&
70 (!vma || addr + len <= vm_start_gap(vma)))
71 return addr;
72 }
73
74 info.length = len;
75 info.align_mask = do_color_align ? (PAGE_MASK & shm_align_mask) : 0;
76 info.align_offset = pgoff << PAGE_SHIFT;
77
78 if (dir == DOWN) {
79 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
80 info.low_limit = PAGE_SIZE;
81 info.high_limit = mm->mmap_base;
82 addr = vm_unmapped_area(&info);
83
84 if (!(addr & ~PAGE_MASK))
85 return addr;
86
87 /*
88 * A failed mmap() very likely causes application failure,
89 * so fall back to the bottom-up function here. This scenario
90 * can happen with large stack limits and large mmap()
91 * allocations.
92 */
93 }
94
95 info.low_limit = mm->mmap_base;
96 info.high_limit = TASK_SIZE;
97 return vm_unmapped_area(&info);
98 }
99
100 unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0,
101 unsigned long len, unsigned long pgoff, unsigned long flags)
102 {
103 return arch_get_unmapped_area_common(filp,
104 addr0, len, pgoff, flags, UP);
105 }
106
107 /*
108 * There is no need to export this but sched.h declares the function as
109 * extern so making it static here results in an error.
110 */
111 unsigned long arch_get_unmapped_area_topdown(struct file *filp,
112 unsigned long addr0, unsigned long len, unsigned long pgoff,
113 unsigned long flags)
114 {
115 return arch_get_unmapped_area_common(filp,
116 addr0, len, pgoff, flags, DOWN);
117 }
118
119 bool __virt_addr_valid(const volatile void *kaddr)
120 {
121 unsigned long vaddr = (unsigned long)kaddr;
122
123 if ((vaddr < PAGE_OFFSET) || (vaddr >= MAP_BASE))
124 return false;
125
126 return pfn_valid(PFN_DOWN(virt_to_phys(kaddr)));
127 }
128 EXPORT_SYMBOL_GPL(__virt_addr_valid);
129
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