1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
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/random.h>
10 #include <linux/io.h>
11
12 #define COLOUR_ALIGN(addr,pgoff) \
13 ((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \
14 (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
15
16 /*
17 * We need to ensure that shared mappings are correctly aligned to
18 * avoid aliasing issues with VIPT caches. We need to ensure that
19 * a specific page of an object is always mapped at a multiple of
20 * SHMLBA bytes.
21 *
22 * We unconditionally provide this function for all cases.
23 */
24 unsigned long
25 arch_get_unmapped_area(struct file *filp, unsigned long addr,
26 unsigned long len, unsigned long pgoff, unsigned long flags)
27 {
28 struct mm_struct *mm = current->mm;
29 struct vm_area_struct *vma;
30 int do_align = 0;
31 struct vm_unmapped_area_info info = {
32 .length = len,
33 .low_limit = mm->mmap_base,
34 .high_limit = TASK_SIZE,
35 .align_offset = pgoff << PAGE_SHIFT
36 };
37
38 /*
39 * We only need to do colour alignment if either the I or D
40 * caches alias.
41 */
42 do_align = filp || (flags & MAP_SHARED);
43
44 /*
45 * We enforce the MAP_FIXED case.
46 */
47 if (flags & MAP_FIXED) {
48 if (flags & MAP_SHARED &&
49 (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
50 return -EINVAL;
51 return addr;
52 }
53
54 if (len > TASK_SIZE)
55 return -ENOMEM;
56
57 if (addr) {
58 if (do_align)
59 addr = COLOUR_ALIGN(addr, pgoff);
60 else
61 addr = PAGE_ALIGN(addr);
62
63 vma = find_vma(mm, addr);
64 if (TASK_SIZE - len >= addr &&
65 (!vma || addr + len <= vm_start_gap(vma)))
66 return addr;
67 }
68
69 info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
70 return vm_unmapped_area(&info);
71 }
72
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