| 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 |
|
| 9 | static inline void set_page_poison(struct page *page)
|
| 10 | {
|
| 11 | __set_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
|
| 12 | }
|
| 13 |
|
| 14 | static inline void clear_page_poison(struct page *page)
|
| 15 | {
|
| 16 | __clear_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
|
| 17 | }
|
| 18 |
|
| 19 | static inline bool page_poison(struct page *page)
|
| 20 | {
|
| 21 | return test_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
|
| 22 | }
|
| 23 |
|
| 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 |
|
| 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 |
|
| 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 |
|
| 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 |
|
| 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 |
|
| 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 |
|
| 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 | }
|