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
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
|
/*
* Copyright 2002 Andi Kleen, SuSE Labs.
* Thanks to Ben LaHaise for precious feedback.
*/
#include <linux/highmem.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <asm/processor.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
pte_t *lookup_address(unsigned long address, int *level)
{
pgd_t *pgd = pgd_offset_k(address);
pud_t *pud;
pmd_t *pmd;
if (pgd_none(*pgd))
return NULL;
pud = pud_offset(pgd, address);
if (pud_none(*pud))
return NULL;
pmd = pmd_offset(pud, address);
if (pmd_none(*pmd))
return NULL;
*level = 2;
if (pmd_large(*pmd))
return (pte_t *)pmd;
*level = 3;
return pte_offset_kernel(pmd, address);
}
static struct page *
split_large_page(unsigned long address, pgprot_t prot, pgprot_t ref_prot)
{
unsigned long addr;
struct page *base;
pte_t *pbase;
int i;
base = alloc_pages(GFP_KERNEL, 0);
if (!base)
return NULL;
/*
* page_private is used to track the number of entries in
* the page table page that have non standard attributes.
*/
address = __pa(address);
addr = address & LARGE_PAGE_MASK;
pbase = (pte_t *)page_address(base);
paravirt_alloc_pt(&init_mm, page_to_pfn(base));
for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT,
addr == address ? prot : ref_prot));
}
return base;
}
static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
{
unsigned long flags;
struct page *page;
/* change init_mm */
set_pte_atomic(kpte, pte);
if (SHARED_KERNEL_PMD)
return;
spin_lock_irqsave(&pgd_lock, flags);
for (page = pgd_list; page; page = (struct page *)page->index) {
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pgd = (pgd_t *)page_address(page) + pgd_index(address);
pud = pud_offset(pgd, address);
pmd = pmd_offset(pud, address);
set_pte_atomic((pte_t *)pmd, pte);
}
spin_unlock_irqrestore(&pgd_lock, flags);
}
static int __change_page_attr(struct page *page, pgprot_t prot)
{
pgprot_t ref_prot = PAGE_KERNEL;
struct page *kpte_page;
unsigned long address;
pgprot_t oldprot;
pte_t *kpte;
int level;
BUG_ON(PageHighMem(page));
address = (unsigned long)page_address(page);
kpte = lookup_address(address, &level);
if (!kpte)
return -EINVAL;
oldprot = pte_pgprot(*kpte);
kpte_page = virt_to_page(kpte);
BUG_ON(PageLRU(kpte_page));
BUG_ON(PageCompound(kpte_page));
/*
* Better fail early if someone sets the kernel text to NX.
* Does not cover __inittext
*/
BUG_ON(address >= (unsigned long)&_text &&
address < (unsigned long)&_etext &&
(pgprot_val(prot) & _PAGE_NX));
if ((address & LARGE_PAGE_MASK) < (unsigned long)&_etext)
ref_prot = PAGE_KERNEL_EXEC;
ref_prot = canon_pgprot(ref_prot);
prot = canon_pgprot(prot);
if (level == 3) {
set_pte_atomic(kpte, mk_pte(page, prot));
} else {
struct page *split;
split = split_large_page(address, prot, ref_prot);
if (!split)
return -ENOMEM;
/*
* There's a small window here to waste a bit of RAM:
*/
set_pmd_pte(kpte, address, mk_pte(split, ref_prot));
}
return 0;
}
/*
* Change the page attributes of an page in the linear mapping.
*
* This should be used when a page is mapped with a different caching policy
* than write-back somewhere - some CPUs do not like it when mappings with
* different caching policies exist. This changes the page attributes of the
* in kernel linear mapping too.
*
* The caller needs to ensure that there are no conflicting mappings elsewhere.
* This function only deals with the kernel linear map.
*
* Caller must call global_flush_tlb() after this.
*/
int change_page_attr(struct page *page, int numpages, pgprot_t prot)
{
int err = 0, i;
for (i = 0; i < numpages; i++, page++) {
err = __change_page_attr(page, prot);
if (err)
break;
}
return err;
}
EXPORT_SYMBOL(change_page_attr);
int change_page_attr_addr(unsigned long addr, int numpages, pgprot_t prot)
{
int i;
unsigned long pfn = (addr >> PAGE_SHIFT);
for (i = 0; i < numpages; i++) {
if (!pfn_valid(pfn + i)) {
break;
} else {
int level;
pte_t *pte = lookup_address(addr + i*PAGE_SIZE, &level);
BUG_ON(pte && !pte_none(*pte));
}
}
return change_page_attr(virt_to_page(addr), i, prot);
}
static void flush_kernel_map(void *arg)
{
/*
* Flush all to work around Errata in early athlons regarding
* large page flushing.
*/
__flush_tlb_all();
if (boot_cpu_data.x86_model >= 4)
wbinvd();
}
void global_flush_tlb(void)
{
BUG_ON(irqs_disabled());
on_each_cpu(flush_kernel_map, NULL, 1, 1);
}
EXPORT_SYMBOL(global_flush_tlb);
#ifdef CONFIG_DEBUG_PAGEALLOC
void kernel_map_pages(struct page *page, int numpages, int enable)
{
if (PageHighMem(page))
return;
if (!enable) {
debug_check_no_locks_freed(page_address(page),
numpages * PAGE_SIZE);
}
/*
* the return value is ignored - the calls cannot fail,
* large pages are disabled at boot time.
*/
change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
/*
* we should perform an IPI and flush all tlbs,
* but that can deadlock->flush only current cpu.
*/
__flush_tlb_all();
}
#endif
|
