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Merge tag 'v4.7-rc6' into x86/mm, to merge fixes before applying new changes
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6a11f75b 1#include <linux/kernel.h>
8c5fb8ea 2#include <linux/string.h>
6a11f75b 3#include <linux/mm.h>
64212ec5 4#include <linux/highmem.h>
e30825f1 5#include <linux/page_ext.h>
6a11f75b 6#include <linux/poison.h>
77311139 7#include <linux/ratelimit.h>
6a11f75b 8
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9static bool __page_poisoning_enabled __read_mostly;
10static bool want_page_poisoning __read_mostly;
e30825f1 11
8823b1db 12static int early_page_poison_param(char *buf)
e30825f1 13{
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14 if (!buf)
15 return -EINVAL;
2a138dc7 16 return strtobool(buf, &want_page_poisoning);
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17}
18early_param("page_poison", early_page_poison_param);
19
20bool page_poisoning_enabled(void)
21{
22 return __page_poisoning_enabled;
23}
24
25static bool need_page_poisoning(void)
26{
27 return want_page_poisoning;
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28}
29
30static void init_page_poisoning(void)
31{
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32 /*
33 * page poisoning is debug page alloc for some arches. If either
34 * of those options are enabled, enable poisoning
35 */
36 if (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC)) {
37 if (!want_page_poisoning && !debug_pagealloc_enabled())
38 return;
39 } else {
40 if (!want_page_poisoning)
41 return;
42 }
031bc574 43
8823b1db 44 __page_poisoning_enabled = true;
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45}
46
47struct page_ext_operations page_poisoning_ops = {
48 .need = need_page_poisoning,
49 .init = init_page_poisoning,
50};
51
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52static inline void set_page_poison(struct page *page)
53{
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54 struct page_ext *page_ext;
55
56 page_ext = lookup_page_ext(page);
f86e4271
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57 if (unlikely(!page_ext))
58 return;
59
e30825f1 60 __set_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
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61}
62
63static inline void clear_page_poison(struct page *page)
64{
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65 struct page_ext *page_ext;
66
67 page_ext = lookup_page_ext(page);
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68 if (unlikely(!page_ext))
69 return;
70
e30825f1 71 __clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
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72}
73
1414c7f4 74bool page_is_poisoned(struct page *page)
6a11f75b 75{
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76 struct page_ext *page_ext;
77
78 page_ext = lookup_page_ext(page);
f86e4271 79 if (unlikely(!page_ext))
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80 return false;
81
e30825f1 82 return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
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83}
84
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85static void poison_page(struct page *page)
86{
64212ec5 87 void *addr = kmap_atomic(page);
6a11f75b 88
6a11f75b 89 set_page_poison(page);
6a11f75b 90 memset(addr, PAGE_POISON, PAGE_SIZE);
64212ec5 91 kunmap_atomic(addr);
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92}
93
94static void poison_pages(struct page *page, int n)
95{
96 int i;
97
98 for (i = 0; i < n; i++)
99 poison_page(page + i);
100}
101
102static bool single_bit_flip(unsigned char a, unsigned char b)
103{
104 unsigned char error = a ^ b;
105
106 return error && !(error & (error - 1));
107}
108
109static void check_poison_mem(unsigned char *mem, size_t bytes)
110{
77311139 111 static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10);
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112 unsigned char *start;
113 unsigned char *end;
114
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115 if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY))
116 return;
117
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118 start = memchr_inv(mem, PAGE_POISON, bytes);
119 if (!start)
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120 return;
121
122 for (end = mem + bytes - 1; end > start; end--) {
123 if (*end != PAGE_POISON)
124 break;
125 }
126
77311139 127 if (!__ratelimit(&ratelimit))
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128 return;
129 else if (start == end && single_bit_flip(*start, PAGE_POISON))
8823b1db 130 pr_err("pagealloc: single bit error\n");
6a11f75b 131 else
8823b1db 132 pr_err("pagealloc: memory corruption\n");
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133
134 print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start,
135 end - start + 1, 1);
136 dump_stack();
137}
138
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139static void unpoison_page(struct page *page)
140{
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141 void *addr;
142
1414c7f4 143 if (!page_is_poisoned(page))
6a11f75b 144 return;
6a11f75b 145
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146 addr = kmap_atomic(page);
147 check_poison_mem(addr, PAGE_SIZE);
148 clear_page_poison(page);
149 kunmap_atomic(addr);
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150}
151
152static void unpoison_pages(struct page *page, int n)
153{
154 int i;
155
156 for (i = 0; i < n; i++)
157 unpoison_page(page + i);
158}
159
8823b1db 160void kernel_poison_pages(struct page *page, int numpages, int enable)
6a11f75b 161{
8823b1db 162 if (!page_poisoning_enabled())
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163 return;
164
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165 if (enable)
166 unpoison_pages(page, numpages);
167 else
168 poison_pages(page, numpages);
169}
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170
171#ifndef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC
172void __kernel_map_pages(struct page *page, int numpages, int enable)
173{
174 /* This function does nothing, all work is done via poison pages */
175}
176#endif