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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> |
56a3271e | 9 | #include <linux/kasan.h> |
6a11f75b | 10 | |
8823b1db | 11 | static bool want_page_poisoning __read_mostly; |
e30825f1 | 12 | |
8823b1db | 13 | static int 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 | ||
21 | bool page_poisoning_enabled(void) | |
e30825f1 | 22 | { |
8823b1db | 23 | /* |
bd33ef36 VM |
24 | * Assumes that debug_pagealloc_enabled is set before |
25 | * free_all_bootmem. | |
26 | * Page poisoning is debug page alloc for some arches. If | |
27 | * either of those options are enabled, enable poisoning. | |
8823b1db | 28 | */ |
bd33ef36 VM |
29 | return (want_page_poisoning || |
30 | (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && | |
31 | debug_pagealloc_enabled())); | |
6a11f75b AM |
32 | } |
33 | ||
6a11f75b AM |
34 | static void poison_page(struct page *page) |
35 | { | |
64212ec5 | 36 | void *addr = kmap_atomic(page); |
6a11f75b | 37 | |
56a3271e QC |
38 | /* KASAN still think the page is in-use, so skip it. */ |
39 | kasan_disable_current(); | |
6a11f75b | 40 | memset(addr, PAGE_POISON, PAGE_SIZE); |
56a3271e | 41 | kasan_enable_current(); |
64212ec5 | 42 | kunmap_atomic(addr); |
6a11f75b AM |
43 | } |
44 | ||
45 | static void poison_pages(struct page *page, int n) | |
46 | { | |
47 | int i; | |
48 | ||
49 | for (i = 0; i < n; i++) | |
50 | poison_page(page + i); | |
51 | } | |
52 | ||
53 | static bool single_bit_flip(unsigned char a, unsigned char b) | |
54 | { | |
55 | unsigned char error = a ^ b; | |
56 | ||
57 | return error && !(error & (error - 1)); | |
58 | } | |
59 | ||
60 | static void check_poison_mem(unsigned char *mem, size_t bytes) | |
61 | { | |
77311139 | 62 | static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10); |
6a11f75b AM |
63 | unsigned char *start; |
64 | unsigned char *end; | |
65 | ||
8823b1db LA |
66 | if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY)) |
67 | return; | |
68 | ||
8c5fb8ea AM |
69 | start = memchr_inv(mem, PAGE_POISON, bytes); |
70 | if (!start) | |
6a11f75b AM |
71 | return; |
72 | ||
73 | for (end = mem + bytes - 1; end > start; end--) { | |
74 | if (*end != PAGE_POISON) | |
75 | break; | |
76 | } | |
77 | ||
77311139 | 78 | if (!__ratelimit(&ratelimit)) |
6a11f75b AM |
79 | return; |
80 | else if (start == end && single_bit_flip(*start, PAGE_POISON)) | |
8823b1db | 81 | pr_err("pagealloc: single bit error\n"); |
6a11f75b | 82 | else |
8823b1db | 83 | pr_err("pagealloc: memory corruption\n"); |
6a11f75b AM |
84 | |
85 | print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start, | |
86 | end - start + 1, 1); | |
87 | dump_stack(); | |
88 | } | |
89 | ||
6a11f75b AM |
90 | static void unpoison_page(struct page *page) |
91 | { | |
64212ec5 AM |
92 | void *addr; |
93 | ||
64212ec5 | 94 | addr = kmap_atomic(page); |
bd33ef36 VM |
95 | /* |
96 | * Page poisoning when enabled poisons each and every page | |
97 | * that is freed to buddy. Thus no extra check is done to | |
98 | * see if a page was posioned. | |
99 | */ | |
64212ec5 | 100 | check_poison_mem(addr, PAGE_SIZE); |
64212ec5 | 101 | kunmap_atomic(addr); |
6a11f75b AM |
102 | } |
103 | ||
104 | static void unpoison_pages(struct page *page, int n) | |
105 | { | |
106 | int i; | |
107 | ||
108 | for (i = 0; i < n; i++) | |
109 | unpoison_page(page + i); | |
110 | } | |
111 | ||
8823b1db | 112 | void kernel_poison_pages(struct page *page, int numpages, int enable) |
6a11f75b | 113 | { |
8823b1db | 114 | if (!page_poisoning_enabled()) |
e30825f1 JK |
115 | return; |
116 | ||
6a11f75b AM |
117 | if (enable) |
118 | unpoison_pages(page, numpages); | |
119 | else | |
120 | poison_pages(page, numpages); | |
121 | } | |
8823b1db LA |
122 | |
123 | #ifndef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC | |
124 | void __kernel_map_pages(struct page *page, int numpages, int enable) | |
125 | { | |
126 | /* This function does nothing, all work is done via poison pages */ | |
127 | } | |
128 | #endif |