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);
71}
72