1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
/*
* Copyright (c) 2014, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/vmalloc.h>
#include <asm/pgtable.h>
#include <asm/set_memory.h>
#include <asm/tlbflush.h>
struct page_change_data {
pgprot_t set_mask;
pgprot_t clear_mask;
};
bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED);
static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr,
void *data)
{
struct page_change_data *cdata = data;
pte_t pte = READ_ONCE(*ptep);
pte = clear_pte_bit(pte, cdata->clear_mask);
pte = set_pte_bit(pte, cdata->set_mask);
set_pte(ptep, pte);
return 0;
}
/*
* This function assumes that the range is mapped with PAGE_SIZE pages.
*/
static int __change_memory_common(unsigned long start, unsigned long size,
pgprot_t set_mask, pgprot_t clear_mask)
{
struct page_change_data data;
int ret;
data.set_mask = set_mask;
data.clear_mask = clear_mask;
ret = apply_to_page_range(&init_mm, start, size, change_page_range,
&data);
flush_tlb_kernel_range(start, start + size);
return ret;
}
static int change_memory_common(unsigned long addr, int numpages,
pgprot_t set_mask, pgprot_t clear_mask)
{
unsigned long start = addr;
unsigned long size = PAGE_SIZE*numpages;
unsigned long end = start + size;
struct vm_struct *area;
int i;
if (!PAGE_ALIGNED(addr)) {
start &= PAGE_MASK;
end = start + size;
WARN_ON_ONCE(1);
}
/*
* Kernel VA mappings are always live, and splitting live section
* mappings into page mappings may cause TLB conflicts. This means
* we have to ensure that changing the permission bits of the range
* we are operating on does not result in such splitting.
*
* Let's restrict ourselves to mappings created by vmalloc (or vmap).
* Those are guaranteed to consist entirely of page mappings, and
* splitting is never needed.
*
* So check whether the [addr, addr + size) interval is entirely
* covered by precisely one VM area that has the VM_ALLOC flag set.
*/
area = find_vm_area((void *)addr);
if (!area ||
end > (unsigned long)area->addr + area->size ||
!(area->flags & VM_ALLOC))
return -EINVAL;
if (!numpages)
return 0;
/*
* If we are manipulating read-only permissions, apply the same
* change to the linear mapping of the pages that back this VM area.
*/
if (rodata_full && (pgprot_val(set_mask) == PTE_RDONLY ||
pgprot_val(clear_mask) == PTE_RDONLY)) {
for (i = 0; i < area->nr_pages; i++) {
__change_memory_common((u64)page_address(area->pages[i]),
PAGE_SIZE, set_mask, clear_mask);
}
}
/*
* Get rid of potentially aliasing lazily unmapped vm areas that may
* have permissions set that deviate from the ones we are setting here.
*/
vm_unmap_aliases();
return __change_memory_common(start, size, set_mask, clear_mask);
}
int set_memory_ro(unsigned long addr, int numpages)
{
return change_memory_common(addr, numpages,
__pgprot(PTE_RDONLY),
__pgprot(PTE_WRITE));
}
int set_memory_rw(unsigned long addr, int numpages)
{
return change_memory_common(addr, numpages,
__pgprot(PTE_WRITE),
__pgprot(PTE_RDONLY));
}
int set_memory_nx(unsigned long addr, int numpages)
{
return change_memory_common(addr, numpages,
__pgprot(PTE_PXN),
__pgprot(0));
}
EXPORT_SYMBOL_GPL(set_memory_nx);
int set_memory_x(unsigned long addr, int numpages)
{
return change_memory_common(addr, numpages,
__pgprot(0),
__pgprot(PTE_PXN));
}
EXPORT_SYMBOL_GPL(set_memory_x);
int set_memory_valid(unsigned long addr, int numpages, int enable)
{
if (enable)
return __change_memory_common(addr, PAGE_SIZE * numpages,
__pgprot(PTE_VALID),
__pgprot(0));
else
return __change_memory_common(addr, PAGE_SIZE * numpages,
__pgprot(0),
__pgprot(PTE_VALID));
}
#ifdef CONFIG_DEBUG_PAGEALLOC
void __kernel_map_pages(struct page *page, int numpages, int enable)
{
set_memory_valid((unsigned long)page_address(page), numpages, enable);
}
#ifdef CONFIG_HIBERNATION
/*
* When built with CONFIG_DEBUG_PAGEALLOC and CONFIG_HIBERNATION, this function
* is used to determine if a linear map page has been marked as not-valid by
* CONFIG_DEBUG_PAGEALLOC. Walk the page table and check the PTE_VALID bit.
* This is based on kern_addr_valid(), which almost does what we need.
*
* Because this is only called on the kernel linear map, p?d_sect() implies
* p?d_present(). When debug_pagealloc is enabled, sections mappings are
* disabled.
*/
bool kernel_page_present(struct page *page)
{
pgd_t *pgdp;
pud_t *pudp, pud;
pmd_t *pmdp, pmd;
pte_t *ptep;
unsigned long addr = (unsigned long)page_address(page);
pgdp = pgd_offset_k(addr);
if (pgd_none(READ_ONCE(*pgdp)))
return false;
pudp = pud_offset(pgdp, addr);
pud = READ_ONCE(*pudp);
if (pud_none(pud))
return false;
if (pud_sect(pud))
return true;
pmdp = pmd_offset(pudp, addr);
pmd = READ_ONCE(*pmdp);
if (pmd_none(pmd))
return false;
if (pmd_sect(pmd))
return true;
ptep = pte_offset_kernel(pmdp, addr);
return pte_valid(READ_ONCE(*ptep));
}
#endif /* CONFIG_HIBERNATION */
#endif /* CONFIG_DEBUG_PAGEALLOC */
|
