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
230
231
232
233
234
235
|
/*
* Copyright 2002 Andi Kleen, SuSE Labs.
* Thanks to Ben LaHaise for precious feedback.
*/
#include <linux/config.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/highmem.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
#include <asm/tlbflush.h>
#include <asm/io.h>
static inline pte_t *lookup_address(unsigned long address)
{
pgd_t *pgd = pgd_offset_k(address);
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
if (pgd_none(*pgd))
return NULL;
pud = pud_offset(pgd, address);
if (!pud_present(*pud))
return NULL;
pmd = pmd_offset(pud, address);
if (!pmd_present(*pmd))
return NULL;
if (pmd_large(*pmd))
return (pte_t *)pmd;
pte = pte_offset_kernel(pmd, address);
if (pte && !pte_present(*pte))
pte = NULL;
return pte;
}
static struct page *split_large_page(unsigned long address, pgprot_t prot,
pgprot_t ref_prot)
{
int i;
unsigned long addr;
struct page *base = alloc_pages(GFP_KERNEL, 0);
pte_t *pbase;
if (!base)
return NULL;
address = __pa(address);
addr = address & LARGE_PAGE_MASK;
pbase = (pte_t *)page_address(base);
for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
pbase[i] = pfn_pte(addr >> PAGE_SHIFT,
addr == address ? prot : ref_prot);
}
return base;
}
static void flush_kernel_map(void *address)
{
if (0 && address && cpu_has_clflush) {
/* is this worth it? */
int i;
for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size)
asm volatile("clflush (%0)" :: "r" (address + i));
} else
asm volatile("wbinvd":::"memory");
if (address)
__flush_tlb_one(address);
else
__flush_tlb_all();
}
static inline void flush_map(unsigned long address)
{
on_each_cpu(flush_kernel_map, (void *)address, 1, 1);
}
struct deferred_page {
struct deferred_page *next;
struct page *fpage;
unsigned long address;
};
static struct deferred_page *df_list; /* protected by init_mm.mmap_sem */
static inline void save_page(unsigned long address, struct page *fpage)
{
struct deferred_page *df;
df = kmalloc(sizeof(struct deferred_page), GFP_KERNEL);
if (!df) {
flush_map(address);
__free_page(fpage);
} else {
df->next = df_list;
df->fpage = fpage;
df->address = address;
df_list = df;
}
}
/*
* No more special protections in this 2/4MB area - revert to a
* large page again.
*/
static void revert_page(unsigned long address, pgprot_t ref_prot)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t large_pte;
pgd = pgd_offset_k(address);
BUG_ON(pgd_none(*pgd));
pud = pud_offset(pgd,address);
BUG_ON(pud_none(*pud));
pmd = pmd_offset(pud, address);
BUG_ON(pmd_val(*pmd) & _PAGE_PSE);
pgprot_val(ref_prot) |= _PAGE_PSE;
large_pte = mk_pte_phys(__pa(address) & LARGE_PAGE_MASK, ref_prot);
set_pte((pte_t *)pmd, large_pte);
}
static int
__change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot,
pgprot_t ref_prot)
{
pte_t *kpte;
struct page *kpte_page;
unsigned kpte_flags;
kpte = lookup_address(address);
if (!kpte) return 0;
kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
kpte_flags = pte_val(*kpte);
if (pgprot_val(prot) != pgprot_val(ref_prot)) {
if ((kpte_flags & _PAGE_PSE) == 0) {
set_pte(kpte, pfn_pte(pfn, prot));
} else {
/*
* split_large_page will take the reference for this change_page_attr
* on the split page.
*/
struct page *split = split_large_page(address, prot, ref_prot);
if (!split)
return -ENOMEM;
set_pte(kpte,mk_pte(split, ref_prot));
kpte_page = split;
}
get_page(kpte_page);
} else if ((kpte_flags & _PAGE_PSE) == 0) {
set_pte(kpte, pfn_pte(pfn, ref_prot));
__put_page(kpte_page);
} else
BUG();
/* on x86-64 the direct mapping set at boot is not using 4k pages */
BUG_ON(PageReserved(kpte_page));
switch (page_count(kpte_page)) {
case 1:
save_page(address, kpte_page);
revert_page(address, ref_prot);
break;
case 0:
BUG(); /* memleak and failed 2M page regeneration */
}
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_addr(unsigned long address, int numpages, pgprot_t prot)
{
int err = 0;
int i;
down_write(&init_mm.mmap_sem);
for (i = 0; i < numpages; i++, address += PAGE_SIZE) {
unsigned long pfn = __pa(address) >> PAGE_SHIFT;
err = __change_page_attr(address, pfn, prot, PAGE_KERNEL);
if (err)
break;
/* Handle kernel mapping too which aliases part of the
* lowmem */
if (__pa(address) < KERNEL_TEXT_SIZE) {
unsigned long addr2;
pgprot_t prot2 = prot;
addr2 = __START_KERNEL_map + __pa(address);
pgprot_val(prot2) &= ~_PAGE_NX;
err = __change_page_attr(addr2, pfn, prot2, PAGE_KERNEL_EXEC);
}
}
up_write(&init_mm.mmap_sem);
return err;
}
/* Don't call this for MMIO areas that may not have a mem_map entry */
int change_page_attr(struct page *page, int numpages, pgprot_t prot)
{
unsigned long addr = (unsigned long)page_address(page);
return change_page_attr_addr(addr, numpages, prot);
}
void global_flush_tlb(void)
{
struct deferred_page *df, *next_df;
down_read(&init_mm.mmap_sem);
df = xchg(&df_list, NULL);
up_read(&init_mm.mmap_sem);
if (!df)
return;
flush_map((df && !df->next) ? df->address : 0);
for (; df; df = next_df) {
next_df = df->next;
if (df->fpage)
__free_page(df->fpage);
kfree(df);
}
}
EXPORT_SYMBOL(change_page_attr);
EXPORT_SYMBOL(global_flush_tlb);
|
