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
set_page_poison(struct page * page)9 static inline void set_page_poison(struct page *page)
10 {
11 __set_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
12 }
13
clear_page_poison(struct page * page)14 static inline void clear_page_poison(struct page *page)
15 {
16 __clear_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
17 }
18
page_poison(struct page * page)19 static inline bool page_poison(struct page *page)
20 {
21 return test_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
22 }
23
poison_page(struct page * page)24 static 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
poison_pages(struct page * page,int n)33 static 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
single_bit_flip(unsigned char a,unsigned char b)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
check_poison_mem(unsigned char * mem,size_t bytes)48 static 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
unpoison_page(struct page * page)75 static 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
unpoison_pages(struct page * page,int n)88 static 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
kernel_map_pages(struct page * page,int numpages,int enable)96 void 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 }
103