1 #include <linux/kernel.h>
2 #include <linux/string.h>
4 #include <linux/highmem.h>
5 #include <linux/page_ext.h>
6 #include <linux/poison.h>
7 #include <linux/ratelimit.h>
9 static bool page_poisoning_enabled __read_mostly
;
11 static bool need_page_poisoning(void)
16 static void init_page_poisoning(void)
18 page_poisoning_enabled
= true;
21 struct page_ext_operations page_poisoning_ops
= {
22 .need
= need_page_poisoning
,
23 .init
= init_page_poisoning
,
26 static inline void set_page_poison(struct page
*page
)
28 struct page_ext
*page_ext
;
30 page_ext
= lookup_page_ext(page
);
31 __set_bit(PAGE_EXT_DEBUG_POISON
, &page_ext
->flags
);
34 static inline void clear_page_poison(struct page
*page
)
36 struct page_ext
*page_ext
;
38 page_ext
= lookup_page_ext(page
);
39 __clear_bit(PAGE_EXT_DEBUG_POISON
, &page_ext
->flags
);
42 static inline bool page_poison(struct page
*page
)
44 struct page_ext
*page_ext
;
46 page_ext
= lookup_page_ext(page
);
47 return test_bit(PAGE_EXT_DEBUG_POISON
, &page_ext
->flags
);
50 static void poison_page(struct page
*page
)
52 void *addr
= kmap_atomic(page
);
54 set_page_poison(page
);
55 memset(addr
, PAGE_POISON
, PAGE_SIZE
);
59 static void poison_pages(struct page
*page
, int n
)
63 for (i
= 0; i
< n
; i
++)
64 poison_page(page
+ i
);
67 static bool single_bit_flip(unsigned char a
, unsigned char b
)
69 unsigned char error
= a
^ b
;
71 return error
&& !(error
& (error
- 1));
74 static void check_poison_mem(unsigned char *mem
, size_t bytes
)
76 static DEFINE_RATELIMIT_STATE(ratelimit
, 5 * HZ
, 10);
80 start
= memchr_inv(mem
, PAGE_POISON
, bytes
);
84 for (end
= mem
+ bytes
- 1; end
> start
; end
--) {
85 if (*end
!= PAGE_POISON
)
89 if (!__ratelimit(&ratelimit
))
91 else if (start
== end
&& single_bit_flip(*start
, PAGE_POISON
))
92 printk(KERN_ERR
"pagealloc: single bit error\n");
94 printk(KERN_ERR
"pagealloc: memory corruption\n");
96 print_hex_dump(KERN_ERR
, "", DUMP_PREFIX_ADDRESS
, 16, 1, start
,
101 static void unpoison_page(struct page
*page
)
105 if (!page_poison(page
))
108 addr
= kmap_atomic(page
);
109 check_poison_mem(addr
, PAGE_SIZE
);
110 clear_page_poison(page
);
114 static void unpoison_pages(struct page
*page
, int n
)
118 for (i
= 0; i
< n
; i
++)
119 unpoison_page(page
+ i
);
122 void kernel_map_pages(struct page
*page
, int numpages
, int enable
)
124 if (!page_poisoning_enabled
)
128 unpoison_pages(page
, numpages
);
130 poison_pages(page
, numpages
);