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 | 9 | static bool want_page_poisoning __read_mostly; |
e30825f1 | 10 | |
8823b1db | 11 | static int early_page_poison_param(char *buf) |
e30825f1 | 12 | { |
8823b1db LA |
13 | if (!buf) |
14 | return -EINVAL; | |
2a138dc7 | 15 | return strtobool(buf, &want_page_poisoning); |
8823b1db LA |
16 | } |
17 | early_param("page_poison", early_page_poison_param); | |
18 | ||
19 | bool page_poisoning_enabled(void) | |
e30825f1 | 20 | { |
8823b1db | 21 | /* |
bd33ef36 VM |
22 | * Assumes that debug_pagealloc_enabled is set before |
23 | * free_all_bootmem. | |
24 | * Page poisoning is debug page alloc for some arches. If | |
25 | * either of those options are enabled, enable poisoning. | |
8823b1db | 26 | */ |
bd33ef36 VM |
27 | return (want_page_poisoning || |
28 | (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && | |
29 | debug_pagealloc_enabled())); | |
6a11f75b AM |
30 | } |
31 | ||
6a11f75b AM |
32 | static void poison_page(struct page *page) |
33 | { | |
64212ec5 | 34 | void *addr = kmap_atomic(page); |
6a11f75b | 35 | |
6a11f75b | 36 | memset(addr, PAGE_POISON, PAGE_SIZE); |
64212ec5 | 37 | kunmap_atomic(addr); |
6a11f75b AM |
38 | } |
39 | ||
40 | static void poison_pages(struct page *page, int n) | |
41 | { | |
42 | int i; | |
43 | ||
44 | for (i = 0; i < n; i++) | |
45 | poison_page(page + i); | |
46 | } | |
47 | ||
48 | static bool single_bit_flip(unsigned char a, unsigned char b) | |
49 | { | |
50 | unsigned char error = a ^ b; | |
51 | ||
52 | return error && !(error & (error - 1)); | |
53 | } | |
54 | ||
55 | static void check_poison_mem(unsigned char *mem, size_t bytes) | |
56 | { | |
77311139 | 57 | static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10); |
6a11f75b AM |
58 | unsigned char *start; |
59 | unsigned char *end; | |
60 | ||
8823b1db LA |
61 | if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY)) |
62 | return; | |
63 | ||
8c5fb8ea AM |
64 | start = memchr_inv(mem, PAGE_POISON, bytes); |
65 | if (!start) | |
6a11f75b AM |
66 | return; |
67 | ||
68 | for (end = mem + bytes - 1; end > start; end--) { | |
69 | if (*end != PAGE_POISON) | |
70 | break; | |
71 | } | |
72 | ||
77311139 | 73 | if (!__ratelimit(&ratelimit)) |
6a11f75b AM |
74 | return; |
75 | else if (start == end && single_bit_flip(*start, PAGE_POISON)) | |
8823b1db | 76 | pr_err("pagealloc: single bit error\n"); |
6a11f75b | 77 | else |
8823b1db | 78 | pr_err("pagealloc: memory corruption\n"); |
6a11f75b AM |
79 | |
80 | print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start, | |
81 | end - start + 1, 1); | |
82 | dump_stack(); | |
83 | } | |
84 | ||
6a11f75b AM |
85 | static void unpoison_page(struct page *page) |
86 | { | |
64212ec5 AM |
87 | void *addr; |
88 | ||
64212ec5 | 89 | addr = kmap_atomic(page); |
bd33ef36 VM |
90 | /* |
91 | * Page poisoning when enabled poisons each and every page | |
92 | * that is freed to buddy. Thus no extra check is done to | |
93 | * see if a page was posioned. | |
94 | */ | |
64212ec5 | 95 | check_poison_mem(addr, PAGE_SIZE); |
64212ec5 | 96 | kunmap_atomic(addr); |
6a11f75b AM |
97 | } |
98 | ||
99 | static void unpoison_pages(struct page *page, int n) | |
100 | { | |
101 | int i; | |
102 | ||
103 | for (i = 0; i < n; i++) | |
104 | unpoison_page(page + i); | |
105 | } | |
106 | ||
8823b1db | 107 | void kernel_poison_pages(struct page *page, int numpages, int enable) |
6a11f75b | 108 | { |
8823b1db | 109 | if (!page_poisoning_enabled()) |
e30825f1 JK |
110 | return; |
111 | ||
6a11f75b AM |
112 | if (enable) |
113 | unpoison_pages(page, numpages); | |
114 | else | |
115 | poison_pages(page, numpages); | |
116 | } | |
8823b1db LA |
117 | |
118 | #ifndef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC | |
119 | void __kernel_map_pages(struct page *page, int numpages, int enable) | |
120 | { | |
121 | /* This function does nothing, all work is done via poison pages */ | |
122 | } | |
123 | #endif |