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