1 #include <linux/kernel.h>
2 #include <linux/string.h>
4 #include <linux/highmem.h>
5 #include <linux/page-debug-flags.h>
6 #include <linux/poison.h>
7 #include <linux/ratelimit.h>
9 static inline void set_page_poison(struct page
*page
)
11 __set_bit(PAGE_DEBUG_FLAG_POISON
, &page
->debug_flags
);
14 static inline void clear_page_poison(struct page
*page
)
16 __clear_bit(PAGE_DEBUG_FLAG_POISON
, &page
->debug_flags
);
19 static inline bool page_poison(struct page
*page
)
21 return test_bit(PAGE_DEBUG_FLAG_POISON
, &page
->debug_flags
);
24 static void poison_page(struct page
*page
)
26 void *addr
= kmap_atomic(page
);
28 set_page_poison(page
);
29 memset(addr
, PAGE_POISON
, PAGE_SIZE
);
33 static void poison_pages(struct page
*page
, int n
)
37 for (i
= 0; i
< n
; i
++)
38 poison_page(page
+ i
);
41 static bool single_bit_flip(unsigned char a
, unsigned char b
)
43 unsigned char error
= a
^ b
;
45 return error
&& !(error
& (error
- 1));
48 static void check_poison_mem(unsigned char *mem
, size_t bytes
)
50 static DEFINE_RATELIMIT_STATE(ratelimit
, 5 * HZ
, 10);
54 start
= memchr_inv(mem
, PAGE_POISON
, bytes
);
58 for (end
= mem
+ bytes
- 1; end
> start
; end
--) {
59 if (*end
!= PAGE_POISON
)
63 if (!__ratelimit(&ratelimit
))
65 else if (start
== end
&& single_bit_flip(*start
, PAGE_POISON
))
66 printk(KERN_ERR
"pagealloc: single bit error\n");
68 printk(KERN_ERR
"pagealloc: memory corruption\n");
70 print_hex_dump(KERN_ERR
, "", DUMP_PREFIX_ADDRESS
, 16, 1, start
,
75 static void unpoison_page(struct page
*page
)
79 if (!page_poison(page
))
82 addr
= kmap_atomic(page
);
83 check_poison_mem(addr
, PAGE_SIZE
);
84 clear_page_poison(page
);
88 static void unpoison_pages(struct page
*page
, int n
)
92 for (i
= 0; i
< n
; i
++)
93 unpoison_page(page
+ i
);
96 void kernel_map_pages(struct page
*page
, int numpages
, int enable
)
99 unpoison_pages(page
, numpages
);
101 poison_pages(page
, numpages
);
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