Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
6a11f75b | 2 | #include <linux/kernel.h> |
8c5fb8ea | 3 | #include <linux/string.h> |
6a11f75b | 4 | #include <linux/mm.h> |
64212ec5 | 5 | #include <linux/highmem.h> |
e30825f1 | 6 | #include <linux/page_ext.h> |
6a11f75b | 7 | #include <linux/poison.h> |
77311139 | 8 | #include <linux/ratelimit.h> |
4117992d | 9 | #include <linux/kasan.h> |
6a11f75b | 10 | |
8823b1db | 11 | static bool want_page_poisoning __read_mostly; |
e30825f1 | 12 | |
14298d36 | 13 | static int __init early_page_poison_param(char *buf) |
e30825f1 | 14 | { |
8823b1db LA |
15 | if (!buf) |
16 | return -EINVAL; | |
2a138dc7 | 17 | return strtobool(buf, &want_page_poisoning); |
8823b1db LA |
18 | } |
19 | early_param("page_poison", early_page_poison_param); | |
20 | ||
d95f58f4 WW |
21 | /** |
22 | * page_poisoning_enabled - check if page poisoning is enabled | |
23 | * | |
24 | * Return true if page poisoning is enabled, or false if not. | |
25 | */ | |
8823b1db | 26 | bool page_poisoning_enabled(void) |
e30825f1 | 27 | { |
8823b1db | 28 | /* |
bd33ef36 | 29 | * Assumes that debug_pagealloc_enabled is set before |
c6ffc5ca | 30 | * memblock_free_all. |
bd33ef36 VM |
31 | * Page poisoning is debug page alloc for some arches. If |
32 | * either of those options are enabled, enable poisoning. | |
8823b1db | 33 | */ |
bd33ef36 VM |
34 | return (want_page_poisoning || |
35 | (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && | |
36 | debug_pagealloc_enabled())); | |
6a11f75b | 37 | } |
d95f58f4 | 38 | EXPORT_SYMBOL_GPL(page_poisoning_enabled); |
6a11f75b | 39 | |
6a11f75b AM |
40 | static void poison_page(struct page *page) |
41 | { | |
64212ec5 | 42 | void *addr = kmap_atomic(page); |
6a11f75b | 43 | |
4117992d QC |
44 | /* KASAN still think the page is in-use, so skip it. */ |
45 | kasan_disable_current(); | |
6a11f75b | 46 | memset(addr, PAGE_POISON, PAGE_SIZE); |
4117992d | 47 | kasan_enable_current(); |
64212ec5 | 48 | kunmap_atomic(addr); |
6a11f75b AM |
49 | } |
50 | ||
51 | static void poison_pages(struct page *page, int n) | |
52 | { | |
53 | int i; | |
54 | ||
55 | for (i = 0; i < n; i++) | |
56 | poison_page(page + i); | |
57 | } | |
58 | ||
59 | static bool single_bit_flip(unsigned char a, unsigned char b) | |
60 | { | |
61 | unsigned char error = a ^ b; | |
62 | ||
63 | return error && !(error & (error - 1)); | |
64 | } | |
65 | ||
66 | static void check_poison_mem(unsigned char *mem, size_t bytes) | |
67 | { | |
77311139 | 68 | static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10); |
6a11f75b AM |
69 | unsigned char *start; |
70 | unsigned char *end; | |
71 | ||
8823b1db LA |
72 | if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY)) |
73 | return; | |
74 | ||
8c5fb8ea AM |
75 | start = memchr_inv(mem, PAGE_POISON, bytes); |
76 | if (!start) | |
6a11f75b AM |
77 | return; |
78 | ||
79 | for (end = mem + bytes - 1; end > start; end--) { | |
80 | if (*end != PAGE_POISON) | |
81 | break; | |
82 | } | |
83 | ||
77311139 | 84 | if (!__ratelimit(&ratelimit)) |
6a11f75b AM |
85 | return; |
86 | else if (start == end && single_bit_flip(*start, PAGE_POISON)) | |
8823b1db | 87 | pr_err("pagealloc: single bit error\n"); |
6a11f75b | 88 | else |
8823b1db | 89 | pr_err("pagealloc: memory corruption\n"); |
6a11f75b AM |
90 | |
91 | print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start, | |
92 | end - start + 1, 1); | |
93 | dump_stack(); | |
94 | } | |
95 | ||
6a11f75b AM |
96 | static void unpoison_page(struct page *page) |
97 | { | |
64212ec5 AM |
98 | void *addr; |
99 | ||
64212ec5 | 100 | addr = kmap_atomic(page); |
bd33ef36 VM |
101 | /* |
102 | * Page poisoning when enabled poisons each and every page | |
103 | * that is freed to buddy. Thus no extra check is done to | |
104 | * see if a page was posioned. | |
105 | */ | |
64212ec5 | 106 | check_poison_mem(addr, PAGE_SIZE); |
64212ec5 | 107 | kunmap_atomic(addr); |
6a11f75b AM |
108 | } |
109 | ||
110 | static void unpoison_pages(struct page *page, int n) | |
111 | { | |
112 | int i; | |
113 | ||
114 | for (i = 0; i < n; i++) | |
115 | unpoison_page(page + i); | |
116 | } | |
117 | ||
8823b1db | 118 | void kernel_poison_pages(struct page *page, int numpages, int enable) |
6a11f75b | 119 | { |
8823b1db | 120 | if (!page_poisoning_enabled()) |
e30825f1 JK |
121 | return; |
122 | ||
6a11f75b AM |
123 | if (enable) |
124 | unpoison_pages(page, numpages); | |
125 | else | |
126 | poison_pages(page, numpages); | |
127 | } | |
8823b1db LA |
128 | |
129 | #ifndef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC | |
130 | void __kernel_map_pages(struct page *page, int numpages, int enable) | |
131 | { | |
132 | /* This function does nothing, all work is done via poison pages */ | |
133 | } | |
134 | #endif |