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
arch_get_unmapped_area(struct file * filp,unsigned long addr,unsigned long len,unsigned long pgoff,unsigned long flags)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
arch_get_unmapped_area_topdown(struct file * filp,const unsigned long addr0,const unsigned long len,const unsigned long pgoff,const unsigned long flags)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  */
valid_phys_addr_range(phys_addr_t addr,size_t size)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  */
valid_mmap_phys_addr_range(unsigned long pfn,size_t size)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