[deliverable/linux.git] / mm / debug-pagealloc.c

#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/page-debug-flags.h>
#include <linux/poison.h>
#include <linux/ratelimit.h>

static inline void set_page_poison(struct page *page)
{
	__set_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
}

static inline void clear_page_poison(struct page *page)
{
	__clear_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
}

static inline bool page_poison(struct page *page)
{
	return test_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
}

static void poison_page(struct page *page)
{
	void *addr = kmap_atomic(page);

	set_page_poison(page);
	memset(addr, PAGE_POISON, PAGE_SIZE);
	kunmap_atomic(addr);
}

static void poison_pages(struct page *page, int n)
{
	int i;

	for (i = 0; i < n; i++)
		poison_page(page + i);
}

static bool single_bit_flip(unsigned char a, unsigned char b)
{
	unsigned char error = a ^ b;

	return error && !(error & (error - 1));
}

static void check_poison_mem(unsigned char *mem, size_t bytes)
{
	static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10);
	unsigned char *start;
	unsigned char *end;

	start = memchr_inv(mem, PAGE_POISON, bytes);
	if (!start)
		return;

	for (end = mem + bytes - 1; end > start; end--) {
		if (*end != PAGE_POISON)
			break;
	}

	if (!__ratelimit(&ratelimit))
		return;
	else if (start == end && single_bit_flip(*start, PAGE_POISON))
		printk(KERN_ERR "pagealloc: single bit error\n");
	else
		printk(KERN_ERR "pagealloc: memory corruption\n");

	print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start,
			end - start + 1, 1);
	dump_stack();
}

static void unpoison_page(struct page *page)
{
	void *addr;

	if (!page_poison(page))
		return;

	addr = kmap_atomic(page);
	check_poison_mem(addr, PAGE_SIZE);
	clear_page_poison(page);
	kunmap_atomic(addr);
}

static void unpoison_pages(struct page *page, int n)
{
	int i;

	for (i = 0; i < n; i++)
		unpoison_page(page + i);
}

void kernel_map_pages(struct page *page, int numpages, int enable)
{
	if (enable)
		unpoison_pages(page, numpages);
	else
		poison_pages(page, numpages);
}
Commit	Line	Data
	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	}