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