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 bool in_range(unsigned long start, unsigned long size,
38	unsigned long range_start, unsigned long range_end)
39{
40	return start >= range_start && start < range_end &&
41		size <= range_end - start;
42}
43
44static int change_memory_common(unsigned long addr, int numpages,
45				pgprot_t set_mask, pgprot_t clear_mask)
46{
47	unsigned long start = addr & PAGE_MASK;
48	unsigned long end = PAGE_ALIGN(addr) + numpages * PAGE_SIZE;
49	unsigned long size = end - start;
50	int ret;
51	struct page_change_data data;
52
53	WARN_ON_ONCE(start != addr);
54
55	if (!size)
56		return 0;
57
58	if (!in_range(start, size, MODULES_VADDR, MODULES_END) &&
59	    !in_range(start, size, VMALLOC_START, VMALLOC_END))
60		return -EINVAL;
61
62	data.set_mask = set_mask;
63	data.clear_mask = clear_mask;
64
65	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
66					&data);
67
68	flush_tlb_kernel_range(start, end);
69	return ret;
70}
71
72int set_memory_ro(unsigned long addr, int numpages)
73{
74	return change_memory_common(addr, numpages,
75					__pgprot(L_PTE_RDONLY),
76					__pgprot(0));
77}
78
79int set_memory_rw(unsigned long addr, int numpages)
80{
81	return change_memory_common(addr, numpages,
82					__pgprot(0),
83					__pgprot(L_PTE_RDONLY));
84}
85
86int set_memory_nx(unsigned long addr, int numpages)
87{
88	return change_memory_common(addr, numpages,
89					__pgprot(L_PTE_XN),
90					__pgprot(0));
91}
92
93int set_memory_x(unsigned long addr, int numpages)
94{
95	return change_memory_common(addr, numpages,
96					__pgprot(0),
97					__pgprot(L_PTE_XN));
98}