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/kernel.h>
14#include <linux/mm.h>
15#include <linux/module.h>
16#include <linux/sched.h>
17
18#include <asm/pgtable.h>
19#include <asm/tlbflush.h>
20
21struct page_change_data {
22	pgprot_t set_mask;
23	pgprot_t clear_mask;
24};
25
26static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr,
27			void *data)
28{
29	struct page_change_data *cdata = data;
30	pte_t pte = *ptep;
31
32	pte = clear_pte_bit(pte, cdata->clear_mask);
33	pte = set_pte_bit(pte, cdata->set_mask);
34
35	set_pte(ptep, pte);
36	return 0;
37}
38
39static int change_memory_common(unsigned long addr, int numpages,
40				pgprot_t set_mask, pgprot_t clear_mask)
41{
42	unsigned long start = addr;
43	unsigned long size = PAGE_SIZE*numpages;
44	unsigned long end = start + size;
45	int ret;
46	struct page_change_data data;
47
48	if (!IS_ALIGNED(addr, PAGE_SIZE)) {
49		start &= PAGE_MASK;
50		end = start + size;
51		WARN_ON_ONCE(1);
52	}
53
54	if (start < MODULES_VADDR || start >= MODULES_END)
55		return -EINVAL;
56
57	if (end < MODULES_VADDR || end >= MODULES_END)
58		return -EINVAL;
59
60	if (!numpages)
61		return 0;
62
63	data.set_mask = set_mask;
64	data.clear_mask = clear_mask;
65
66	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
67					&data);
68
69	flush_tlb_kernel_range(start, end);
70	return ret;
71}
72
73int set_memory_ro(unsigned long addr, int numpages)
74{
75	return change_memory_common(addr, numpages,
76					__pgprot(PTE_RDONLY),
77					__pgprot(PTE_WRITE));
78}
79
80int set_memory_rw(unsigned long addr, int numpages)
81{
82	return change_memory_common(addr, numpages,
83					__pgprot(PTE_WRITE),
84					__pgprot(PTE_RDONLY));
85}
86
87int set_memory_nx(unsigned long addr, int numpages)
88{
89	return change_memory_common(addr, numpages,
90					__pgprot(PTE_PXN),
91					__pgprot(0));
92}
93EXPORT_SYMBOL_GPL(set_memory_nx);
94
95int set_memory_x(unsigned long addr, int numpages)
96{
97	return change_memory_common(addr, numpages,
98					__pgprot(0),
99					__pgprot(PTE_PXN));
100}
101EXPORT_SYMBOL_GPL(set_memory_x);
102