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> |
f58bd538 | 5 | #include <linux/mmdebug.h> |
64212ec5 | 6 | #include <linux/highmem.h> |
e30825f1 | 7 | #include <linux/page_ext.h> |
6a11f75b | 8 | #include <linux/poison.h> |
77311139 | 9 | #include <linux/ratelimit.h> |
4117992d | 10 | #include <linux/kasan.h> |
6a11f75b | 11 | |
8db26a3d VB |
12 | bool _page_poisoning_enabled_early; |
13 | EXPORT_SYMBOL(_page_poisoning_enabled_early); | |
14 | DEFINE_STATIC_KEY_FALSE(_page_poisoning_enabled); | |
15 | EXPORT_SYMBOL(_page_poisoning_enabled); | |
e30825f1 | 16 | |
14298d36 | 17 | static int __init early_page_poison_param(char *buf) |
e30825f1 | 18 | { |
8db26a3d | 19 | return kstrtobool(buf, &_page_poisoning_enabled_early); |
8823b1db LA |
20 | } |
21 | early_param("page_poison", early_page_poison_param); | |
22 | ||
6a11f75b AM |
23 | static void poison_page(struct page *page) |
24 | { | |
64212ec5 | 25 | void *addr = kmap_atomic(page); |
6a11f75b | 26 | |
4117992d QC |
27 | /* KASAN still think the page is in-use, so skip it. */ |
28 | kasan_disable_current(); | |
aa1ef4d7 | 29 | memset(kasan_reset_tag(addr), PAGE_POISON, PAGE_SIZE); |
4117992d | 30 | kasan_enable_current(); |
64212ec5 | 31 | kunmap_atomic(addr); |
6a11f75b AM |
32 | } |
33 | ||
8db26a3d | 34 | void __kernel_poison_pages(struct page *page, int n) |
6a11f75b AM |
35 | { |
36 | int i; | |
37 | ||
38 | for (i = 0; i < n; i++) | |
39 | poison_page(page + i); | |
40 | } | |
41 | ||
42 | static bool single_bit_flip(unsigned char a, unsigned char b) | |
43 | { | |
44 | unsigned char error = a ^ b; | |
45 | ||
46 | return error && !(error & (error - 1)); | |
47 | } | |
48 | ||
f58bd538 | 49 | static void check_poison_mem(struct page *page, unsigned char *mem, size_t bytes) |
6a11f75b | 50 | { |
77311139 | 51 | static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10); |
6a11f75b AM |
52 | unsigned char *start; |
53 | unsigned char *end; | |
54 | ||
8c5fb8ea AM |
55 | start = memchr_inv(mem, PAGE_POISON, bytes); |
56 | if (!start) | |
6a11f75b AM |
57 | return; |
58 | ||
59 | for (end = mem + bytes - 1; end > start; end--) { | |
60 | if (*end != PAGE_POISON) | |
61 | break; | |
62 | } | |
63 | ||
77311139 | 64 | if (!__ratelimit(&ratelimit)) |
6a11f75b AM |
65 | return; |
66 | else if (start == end && single_bit_flip(*start, PAGE_POISON)) | |
8823b1db | 67 | pr_err("pagealloc: single bit error\n"); |
6a11f75b | 68 | else |
8823b1db | 69 | pr_err("pagealloc: memory corruption\n"); |
6a11f75b AM |
70 | |
71 | print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start, | |
72 | end - start + 1, 1); | |
73 | dump_stack(); | |
f58bd538 | 74 | dump_page(page, "pagealloc: corrupted page details"); |
6a11f75b AM |
75 | } |
76 | ||
6a11f75b AM |
77 | static void unpoison_page(struct page *page) |
78 | { | |
64212ec5 AM |
79 | void *addr; |
80 | ||
64212ec5 | 81 | addr = kmap_atomic(page); |
06b1f855 | 82 | kasan_disable_current(); |
bd33ef36 VM |
83 | /* |
84 | * Page poisoning when enabled poisons each and every page | |
85 | * that is freed to buddy. Thus no extra check is done to | |
dbf7684e | 86 | * see if a page was poisoned. |
bd33ef36 | 87 | */ |
f58bd538 | 88 | check_poison_mem(page, kasan_reset_tag(addr), PAGE_SIZE); |
06b1f855 | 89 | kasan_enable_current(); |
64212ec5 | 90 | kunmap_atomic(addr); |
6a11f75b AM |
91 | } |
92 | ||
8db26a3d | 93 | void __kernel_unpoison_pages(struct page *page, int n) |
6a11f75b AM |
94 | { |
95 | int i; | |
96 | ||
97 | for (i = 0; i < n; i++) | |
98 | unpoison_page(page + i); | |
99 | } | |
100 | ||
8823b1db LA |
101 | #ifndef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC |
102 | void __kernel_map_pages(struct page *page, int numpages, int enable) | |
103 | { | |
104 | /* This function does nothing, all work is done via poison pages */ | |
105 | } | |
106 | #endif |