1// SPDX-License-Identifier: GPL-2.0
 2// Copyright (C) 2005-2017 Andes Technology Corporation
 3
 4#include <linux/sched.h>
 5#include <linux/mman.h>
 6#include <linux/shm.h>
 7
 8#define COLOUR_ALIGN(addr,pgoff)		\
 9	((((addr)+SHMLBA-1)&~(SHMLBA-1)) +	\
10	 (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
11
12/*
13 * We need to ensure that shared mappings are correctly aligned to
14 * avoid aliasing issues with VIPT caches.  We need to ensure that
15 * a specific page of an object is always mapped at a multiple of
16 * SHMLBA bytes.
17 *
18 * We unconditionally provide this function for all cases, however
19 * in the VIVT case, we optimise out the alignment rules.
20 */
21unsigned long
22arch_get_unmapped_area(struct file *filp, unsigned long addr,
23		       unsigned long len, unsigned long pgoff,
24		       unsigned long flags)
25{
26	struct mm_struct *mm = current->mm;
27	struct vm_area_struct *vma;
28	int do_align = 0;
29	struct vm_unmapped_area_info info;
30	int aliasing = 0;
31	if(IS_ENABLED(CONFIG_CPU_CACHE_ALIASING))
32		aliasing = 1;
33
34	/*
35	 * We only need to do colour alignment if either the I or D
36	 * caches alias.
37	 */
38	if (aliasing)
39		do_align = filp || (flags & MAP_SHARED);
40
41	/*
42	 * We enforce the MAP_FIXED case.
43	 */
44	if (flags & MAP_FIXED) {
45		if (aliasing && flags & MAP_SHARED &&
46		    (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
47			return -EINVAL;
48		return addr;
49	}
50
51	if (len > TASK_SIZE)
52		return -ENOMEM;
53
54	if (addr) {
55		if (do_align)
56			addr = COLOUR_ALIGN(addr, pgoff);
57		else
58			addr = PAGE_ALIGN(addr);
59
60		vma = find_vma(mm, addr);
61		if (TASK_SIZE - len >= addr &&
62		    (!vma || addr + len <= vma->vm_start))
63			return addr;
64	}
65
66	info.flags = 0;
67	info.length = len;
68	info.low_limit = mm->mmap_base;
69	info.high_limit = TASK_SIZE;
70	info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
71	info.align_offset = pgoff << PAGE_SHIFT;
72	return vm_unmapped_area(&info);
73}