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 (!numpages)
53		return 0;
54
55	if (start < MODULES_VADDR || start >= MODULES_END)
56		return -EINVAL;
57
58	if (end < MODULES_VADDR || start >= MODULES_END)
59		return -EINVAL;
60
61	data.set_mask = set_mask;
62	data.clear_mask = clear_mask;
63
64	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
65					&data);
66
67	flush_tlb_kernel_range(start, end);
68	return ret;
69}
70
71int set_memory_ro(unsigned long addr, int numpages)
72{
73	return change_memory_common(addr, numpages,
74					__pgprot(L_PTE_RDONLY),
75					__pgprot(0));
76}
77
78int set_memory_rw(unsigned long addr, int numpages)
79{
80	return change_memory_common(addr, numpages,
81					__pgprot(0),
82					__pgprot(L_PTE_RDONLY));
83}
84
85int set_memory_nx(unsigned long addr, int numpages)
86{
87	return change_memory_common(addr, numpages,
88					__pgprot(L_PTE_XN),
89					__pgprot(0));
90}
91
92int set_memory_x(unsigned long addr, int numpages)
93{
94	return change_memory_common(addr, numpages,
95					__pgprot(0),
96					__pgprot(L_PTE_XN));
97}