1/*
2 * Copyright (c) 2014, The Linux Foundation. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 and
6 * only version 2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11 * GNU General Public License for more details.
12 */
13#include <linux/mm.h>
14#include <linux/module.h>
15
16#include <asm/pgtable.h>
17#include <asm/tlbflush.h>
18
19struct page_change_data {
20	pgprot_t set_mask;
21	pgprot_t clear_mask;
22};
23
24static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr,
25			void *data)
26{
27	struct page_change_data *cdata = data;
28	pte_t pte = *ptep;
29
30	pte = clear_pte_bit(pte, cdata->clear_mask);
31	pte = set_pte_bit(pte, cdata->set_mask);
32
33	set_pte_ext(ptep, pte, 0);
34	return 0;
35}
36
37static int change_memory_common(unsigned long addr, int numpages,
38				pgprot_t set_mask, pgprot_t clear_mask)
39{
40	unsigned long start = addr;
41	unsigned long size = PAGE_SIZE*numpages;
42	unsigned long end = start + size;
43	int ret;
44	struct page_change_data data;
45
46	if (!IS_ALIGNED(addr, PAGE_SIZE)) {
47		start &= PAGE_MASK;
48		end = start + size;
49		WARN_ON_ONCE(1);
50	}
51
52	if (start < MODULES_VADDR || start >= MODULES_END)
53		return -EINVAL;
54
55	if (end < MODULES_VADDR || start >= MODULES_END)
56		return -EINVAL;
57
58	data.set_mask = set_mask;
59	data.clear_mask = clear_mask;
60
61	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
62					&data);
63
64	flush_tlb_kernel_range(start, end);
65	return ret;
66}
67
68int set_memory_ro(unsigned long addr, int numpages)
69{
70	return change_memory_common(addr, numpages,
71					__pgprot(L_PTE_RDONLY),
72					__pgprot(0));
73}
74
75int set_memory_rw(unsigned long addr, int numpages)
76{
77	return change_memory_common(addr, numpages,
78					__pgprot(0),
79					__pgprot(L_PTE_RDONLY));
80}
81
82int set_memory_nx(unsigned long addr, int numpages)
83{
84	return change_memory_common(addr, numpages,
85					__pgprot(L_PTE_XN),
86					__pgprot(0));
87}
88
89int set_memory_x(unsigned long addr, int numpages)
90{
91	return change_memory_common(addr, numpages,
92					__pgprot(0),
93					__pgprot(L_PTE_XN));
94}
95