1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/kernel.h>
3 #include <linux/string.h>
5 #include <linux/mmdebug.h>
6 #include <linux/highmem.h>
7 #include <linux/page_ext.h>
8 #include <linux/poison.h>
9 #include <linux/ratelimit.h>
10 #include <linux/kasan.h>
12 bool _page_poisoning_enabled_early
;
13 EXPORT_SYMBOL(_page_poisoning_enabled_early
);
14 DEFINE_STATIC_KEY_FALSE(_page_poisoning_enabled
);
15 EXPORT_SYMBOL(_page_poisoning_enabled
);
17 static int __init
early_page_poison_param(char *buf
)
19 return kstrtobool(buf
, &_page_poisoning_enabled_early
);
21 early_param("page_poison", early_page_poison_param
);
23 static void poison_page(struct page
*page
)
25 void *addr
= kmap_atomic(page
);
27 /* KASAN still think the page is in-use, so skip it. */
28 kasan_disable_current();
29 memset(kasan_reset_tag(addr
), PAGE_POISON
, PAGE_SIZE
);
30 kasan_enable_current();
34 void __kernel_poison_pages(struct page
*page
, int n
)
38 for (i
= 0; i
< n
; i
++)
39 poison_page(page
+ i
);
42 static bool single_bit_flip(unsigned char a
, unsigned char b
)
44 unsigned char error
= a
^ b
;
46 return error
&& !(error
& (error
- 1));
49 static void check_poison_mem(struct page
*page
, unsigned char *mem
, size_t bytes
)
51 static DEFINE_RATELIMIT_STATE(ratelimit
, 5 * HZ
, 10);
55 start
= memchr_inv(mem
, PAGE_POISON
, bytes
);
59 for (end
= mem
+ bytes
- 1; end
> start
; end
--) {
60 if (*end
!= PAGE_POISON
)
64 if (!__ratelimit(&ratelimit
))
66 else if (start
== end
&& single_bit_flip(*start
, PAGE_POISON
))
67 pr_err("pagealloc: single bit error\n");
69 pr_err("pagealloc: memory corruption\n");
71 print_hex_dump(KERN_ERR
, "", DUMP_PREFIX_ADDRESS
, 16, 1, start
,
74 dump_page(page
, "pagealloc: corrupted page details");
77 static void unpoison_page(struct page
*page
)
81 addr
= kmap_atomic(page
);
82 kasan_disable_current();
84 * Page poisoning when enabled poisons each and every page
85 * that is freed to buddy. Thus no extra check is done to
86 * see if a page was poisoned.
88 check_poison_mem(page
, kasan_reset_tag(addr
), PAGE_SIZE
);
89 kasan_enable_current();
93 void __kernel_unpoison_pages(struct page
*page
, int n
)
97 for (i
= 0; i
< n
; i
++)
98 unpoison_page(page
+ i
);
101 #ifndef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC
102 void __kernel_map_pages(struct page
*page
, int numpages
, int enable
)
104 /* This function does nothing, all work is done via poison pages */