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 */
24unsigned long
25arch_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
33 /*
34 * We only need to do colour alignment if either the I or D
35 * caches alias.
36 */
37 do_align = filp || (flags & MAP_SHARED);
38
39 /*
40 * We enforce the MAP_FIXED case.
41 */
42 if (flags & MAP_FIXED) {
43 if (flags & MAP_SHARED &&
44 (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
45 return -EINVAL;
46 return addr;
47 }
48
49 if (len > TASK_SIZE)
50 return -ENOMEM;
51
52 if (addr) {
53 if (do_align)
54 addr = COLOUR_ALIGN(addr, pgoff);
55 else
56 addr = PAGE_ALIGN(addr);
57
58 vma = find_vma(mm, addr);
59 if (TASK_SIZE - len >= addr &&
60 (!vma || addr + len <= vm_start_gap(vma)))
61 return addr;
62 }
63
64 info.flags = 0;
65 info.length = len;
66 info.low_limit = mm->mmap_base;
67 info.high_limit = TASK_SIZE;
68 info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
69 info.align_offset = pgoff << PAGE_SHIFT;
70 return vm_unmapped_area(info: &info);
71}
72

source code of linux/arch/csky/abiv1/mmap.c