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1#include <linux/kernel.h>
2#include <linux/mm.h>
3#include <linux/page-debug-flags.h>
4#include <linux/poison.h>
5
6static inline void set_page_poison(struct page *page)
7{
8 __set_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
9}
10
11static inline void clear_page_poison(struct page *page)
12{
13 __clear_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
14}
15
16static inline bool page_poison(struct page *page)
17{
18 return test_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
19}
20
21static void poison_highpage(struct page *page)
22{
23 /*
24 * Page poisoning for highmem pages is not implemented.
25 *
26 * This can be called from interrupt contexts.
27 * So we need to create a new kmap_atomic slot for this
28 * application and it will need interrupt protection.
29 */
30}
31
32static void poison_page(struct page *page)
33{
34 void *addr;
35
36 if (PageHighMem(page)) {
37 poison_highpage(page);
38 return;
39 }
40 set_page_poison(page);
41 addr = page_address(page);
42 memset(addr, PAGE_POISON, PAGE_SIZE);
43}
44
45static 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
53static 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
60static void check_poison_mem(unsigned char *mem, size_t bytes)
61{
62 unsigned char *start;
63 unsigned char *end;
64
65 for (start = mem; start < mem + bytes; start++) {
66 if (*start != PAGE_POISON)
67 break;
68 }
69 if (start == mem + bytes)
70 return;
71
72 for (end = mem + bytes - 1; end > start; end--) {
73 if (*end != PAGE_POISON)
74 break;
75 }
76
77 if (!printk_ratelimit())
78 return;
79 else if (start == end && single_bit_flip(*start, PAGE_POISON))
80 printk(KERN_ERR "pagealloc: single bit error\n");
81 else
82 printk(KERN_ERR "pagealloc: memory corruption\n");
83
84 print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start,
85 end - start + 1, 1);
86 dump_stack();
87}
88
89static void unpoison_highpage(struct page *page)
90{
91 /*
92 * See comment in poison_highpage().
93 * Highmem pages should not be poisoned for now
94 */
95 BUG_ON(page_poison(page));
96}
97
98static void unpoison_page(struct page *page)
99{
100 if (PageHighMem(page)) {
101 unpoison_highpage(page);
102 return;
103 }
104 if (page_poison(page)) {
105 void *addr = page_address(page);
106
107 check_poison_mem(addr, PAGE_SIZE);
108 clear_page_poison(page);
109 }
110}
111
112static void unpoison_pages(struct page *page, int n)
113{
114 int i;
115
116 for (i = 0; i < n; i++)
117 unpoison_page(page + i);
118}
119
120void kernel_map_pages(struct page *page, int numpages, int enable)
121{
122 if (!debug_pagealloc_enabled)
123 return;
124
125 if (enable)
126 unpoison_pages(page, numpages);
127 else
128 poison_pages(page, numpages);
129}
1#include <linux/kernel.h>
2#include <linux/string.h>
3#include <linux/mm.h>
4#include <linux/highmem.h>
5#include <linux/page-debug-flags.h>
6#include <linux/poison.h>
7#include <linux/ratelimit.h>
8
9static inline void set_page_poison(struct page *page)
10{
11 __set_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
12}
13
14static inline void clear_page_poison(struct page *page)
15{
16 __clear_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
17}
18
19static inline bool page_poison(struct page *page)
20{
21 return test_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
22}
23
24static void poison_page(struct page *page)
25{
26 void *addr = kmap_atomic(page);
27
28 set_page_poison(page);
29 memset(addr, PAGE_POISON, PAGE_SIZE);
30 kunmap_atomic(addr);
31}
32
33static void poison_pages(struct page *page, int n)
34{
35 int i;
36
37 for (i = 0; i < n; i++)
38 poison_page(page + i);
39}
40
41static 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
48static void check_poison_mem(unsigned char *mem, size_t bytes)
49{
50 static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10);
51 unsigned char *start;
52 unsigned char *end;
53
54 start = memchr_inv(mem, PAGE_POISON, bytes);
55 if (!start)
56 return;
57
58 for (end = mem + bytes - 1; end > start; end--) {
59 if (*end != PAGE_POISON)
60 break;
61 }
62
63 if (!__ratelimit(&ratelimit))
64 return;
65 else if (start == end && single_bit_flip(*start, PAGE_POISON))
66 printk(KERN_ERR "pagealloc: single bit error\n");
67 else
68 printk(KERN_ERR "pagealloc: memory corruption\n");
69
70 print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start,
71 end - start + 1, 1);
72 dump_stack();
73}
74
75static void unpoison_page(struct page *page)
76{
77 void *addr;
78
79 if (!page_poison(page))
80 return;
81
82 addr = kmap_atomic(page);
83 check_poison_mem(addr, PAGE_SIZE);
84 clear_page_poison(page);
85 kunmap_atomic(addr);
86}
87
88static void unpoison_pages(struct page *page, int n)
89{
90 int i;
91
92 for (i = 0; i < n; i++)
93 unpoison_page(page + i);
94}
95
96void kernel_map_pages(struct page *page, int numpages, int enable)
97{
98 if (enable)
99 unpoison_pages(page, numpages);
100 else
101 poison_pages(page, numpages);
102}