64212ec569
This adds support for highmem pages poisoning and verification to the debug-pagealloc feature for no-architecture support. [akpm@linux-foundation.org: remove unneeded preempt_disable/enable] Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
106 lines
2.1 KiB
C
106 lines
2.1 KiB
C
#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/highmem.h>
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#include <linux/page-debug-flags.h>
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#include <linux/poison.h>
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#include <linux/ratelimit.h>
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static inline void set_page_poison(struct page *page)
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{
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__set_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
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}
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static inline void clear_page_poison(struct page *page)
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{
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__clear_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
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}
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static inline bool page_poison(struct page *page)
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{
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return test_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
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}
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static void poison_page(struct page *page)
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{
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void *addr = kmap_atomic(page);
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set_page_poison(page);
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memset(addr, PAGE_POISON, PAGE_SIZE);
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kunmap_atomic(addr);
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}
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static void poison_pages(struct page *page, int n)
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{
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int i;
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for (i = 0; i < n; i++)
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poison_page(page + i);
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}
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static bool single_bit_flip(unsigned char a, unsigned char b)
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{
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unsigned char error = a ^ b;
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return error && !(error & (error - 1));
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}
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static void check_poison_mem(unsigned char *mem, size_t bytes)
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{
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static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10);
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unsigned char *start;
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unsigned char *end;
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start = memchr_inv(mem, PAGE_POISON, bytes);
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if (!start)
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return;
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for (end = mem + bytes - 1; end > start; end--) {
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if (*end != PAGE_POISON)
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break;
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}
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if (!__ratelimit(&ratelimit))
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return;
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else if (start == end && single_bit_flip(*start, PAGE_POISON))
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printk(KERN_ERR "pagealloc: single bit error\n");
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else
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printk(KERN_ERR "pagealloc: memory corruption\n");
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print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start,
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end - start + 1, 1);
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dump_stack();
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}
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static void unpoison_page(struct page *page)
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{
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void *addr;
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if (!page_poison(page))
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return;
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addr = kmap_atomic(page);
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check_poison_mem(addr, PAGE_SIZE);
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clear_page_poison(page);
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kunmap_atomic(addr);
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}
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static void unpoison_pages(struct page *page, int n)
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{
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int i;
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for (i = 0; i < n; i++)
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unpoison_page(page + i);
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}
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void kernel_map_pages(struct page *page, int numpages, int enable)
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{
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if (!debug_pagealloc_enabled)
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return;
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if (enable)
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unpoison_pages(page, numpages);
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else
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poison_pages(page, numpages);
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}
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