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