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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 | |
11c9c7ed | 11 | static DEFINE_STATIC_KEY_FALSE_RO(want_page_poisoning); |
e30825f1 | 12 | |
14298d36 | 13 | static int __init early_page_poison_param(char *buf) |
e30825f1 | 14 | { |
11c9c7ed MN |
15 | int ret; |
16 | bool tmp; | |
17 | ||
18 | ret = strtobool(buf, &tmp); | |
19 | if (ret) | |
20 | return ret; | |
21 | ||
22 | if (tmp) | |
23 | static_branch_enable(&want_page_poisoning); | |
24 | else | |
25 | static_branch_disable(&want_page_poisoning); | |
26 | ||
27 | return 0; | |
8823b1db LA |
28 | } |
29 | early_param("page_poison", early_page_poison_param); | |
30 | ||
d95f58f4 WW |
31 | /** |
32 | * page_poisoning_enabled - check if page poisoning is enabled | |
33 | * | |
34 | * Return true if page poisoning is enabled, or false if not. | |
35 | */ | |
8823b1db | 36 | bool page_poisoning_enabled(void) |
e30825f1 | 37 | { |
8823b1db | 38 | /* |
bd33ef36 | 39 | * Assumes that debug_pagealloc_enabled is set before |
c6ffc5ca | 40 | * memblock_free_all. |
bd33ef36 VM |
41 | * Page poisoning is debug page alloc for some arches. If |
42 | * either of those options are enabled, enable poisoning. | |
8823b1db | 43 | */ |
11c9c7ed | 44 | return (static_branch_unlikely(&want_page_poisoning) || |
bd33ef36 VM |
45 | (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && |
46 | debug_pagealloc_enabled())); | |
6a11f75b | 47 | } |
d95f58f4 | 48 | EXPORT_SYMBOL_GPL(page_poisoning_enabled); |
6a11f75b | 49 | |
6a11f75b AM |
50 | static void poison_page(struct page *page) |
51 | { | |
64212ec5 | 52 | void *addr = kmap_atomic(page); |
6a11f75b | 53 | |
4117992d QC |
54 | /* KASAN still think the page is in-use, so skip it. */ |
55 | kasan_disable_current(); | |
6a11f75b | 56 | memset(addr, PAGE_POISON, PAGE_SIZE); |
4117992d | 57 | kasan_enable_current(); |
64212ec5 | 58 | kunmap_atomic(addr); |
6a11f75b AM |
59 | } |
60 | ||
61 | static void poison_pages(struct page *page, int n) | |
62 | { | |
63 | int i; | |
64 | ||
65 | for (i = 0; i < n; i++) | |
66 | poison_page(page + i); | |
67 | } | |
68 | ||
69 | static bool single_bit_flip(unsigned char a, unsigned char b) | |
70 | { | |
71 | unsigned char error = a ^ b; | |
72 | ||
73 | return error && !(error & (error - 1)); | |
74 | } | |
75 | ||
76 | static void check_poison_mem(unsigned char *mem, size_t bytes) | |
77 | { | |
77311139 | 78 | static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10); |
6a11f75b AM |
79 | unsigned char *start; |
80 | unsigned char *end; | |
81 | ||
8823b1db LA |
82 | if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY)) |
83 | return; | |
84 | ||
8c5fb8ea AM |
85 | start = memchr_inv(mem, PAGE_POISON, bytes); |
86 | if (!start) | |
6a11f75b AM |
87 | return; |
88 | ||
89 | for (end = mem + bytes - 1; end > start; end--) { | |
90 | if (*end != PAGE_POISON) | |
91 | break; | |
92 | } | |
93 | ||
77311139 | 94 | if (!__ratelimit(&ratelimit)) |
6a11f75b AM |
95 | return; |
96 | else if (start == end && single_bit_flip(*start, PAGE_POISON)) | |
8823b1db | 97 | pr_err("pagealloc: single bit error\n"); |
6a11f75b | 98 | else |
8823b1db | 99 | pr_err("pagealloc: memory corruption\n"); |
6a11f75b AM |
100 | |
101 | print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start, | |
102 | end - start + 1, 1); | |
103 | dump_stack(); | |
104 | } | |
105 | ||
6a11f75b AM |
106 | static void unpoison_page(struct page *page) |
107 | { | |
64212ec5 AM |
108 | void *addr; |
109 | ||
64212ec5 | 110 | addr = kmap_atomic(page); |
bd33ef36 VM |
111 | /* |
112 | * Page poisoning when enabled poisons each and every page | |
113 | * that is freed to buddy. Thus no extra check is done to | |
dbf7684e | 114 | * see if a page was poisoned. |
bd33ef36 | 115 | */ |
64212ec5 | 116 | check_poison_mem(addr, PAGE_SIZE); |
64212ec5 | 117 | kunmap_atomic(addr); |
6a11f75b AM |
118 | } |
119 | ||
120 | static void unpoison_pages(struct page *page, int n) | |
121 | { | |
122 | int i; | |
123 | ||
124 | for (i = 0; i < n; i++) | |
125 | unpoison_page(page + i); | |
126 | } | |
127 | ||
8823b1db | 128 | void kernel_poison_pages(struct page *page, int numpages, int enable) |
6a11f75b | 129 | { |
8823b1db | 130 | if (!page_poisoning_enabled()) |
e30825f1 JK |
131 | return; |
132 | ||
6a11f75b AM |
133 | if (enable) |
134 | unpoison_pages(page, numpages); | |
135 | else | |
136 | poison_pages(page, numpages); | |
137 | } | |
8823b1db LA |
138 | |
139 | #ifndef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC | |
140 | void __kernel_map_pages(struct page *page, int numpages, int enable) | |
141 | { | |
142 | /* This function does nothing, all work is done via poison pages */ | |
143 | } | |
144 | #endif |