[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_ext.h>
#include <linux/poison.h>
#include <linux/ratelimit.h>

static bool page_poisoning_enabled __read_mostly;

static bool need_page_poisoning(void)
{
	if (!debug_pagealloc_enabled())
		return false;

	return true;
}

static void init_page_poisoning(void)
{
	if (!debug_pagealloc_enabled())
		return;

	page_poisoning_enabled = true;
}

struct page_ext_operations page_poisoning_ops = {
	.need = need_page_poisoning,
	.init = init_page_poisoning,
};

static inline void set_page_poison(struct page *page)
{
	struct page_ext *page_ext;

	page_ext = lookup_page_ext(page);
	__set_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
}

static inline void clear_page_poison(struct page *page)
{
	struct page_ext *page_ext;

	page_ext = lookup_page_ext(page);
	__clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
}

static inline bool page_poison(struct page *page)
{
	struct page_ext *page_ext;

	page_ext = lookup_page_ext(page);
	return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->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 (!page_poisoning_enabled)
		return;

	if (enable)
		unpoison_pages(page, numpages);
	else
		poison_pages(page, numpages);
}
Commit	Line	Data
6a11f75b	1	#include <linux/kernel.h>
8c5fb8ea	2	#include <linux/string.h>
6a11f75b	3	#include <linux/mm.h>
64212ec5	4	#include <linux/highmem.h>
e30825f1	5	#include <linux/page_ext.h>
6a11f75b	6	#include <linux/poison.h>
77311139	7	#include <linux/ratelimit.h>
6a11f75b	8
e30825f1 JK	9	static bool page_poisoning_enabled __read_mostly;
	10
	11	static bool need_page_poisoning(void)
	12	{
031bc574 JK	13	if (!debug_pagealloc_enabled())
	14	return false;
	15
e30825f1 JK	16	return true;
	17	}
	18
	19	static void init_page_poisoning(void)
	20	{
031bc574 JK	21	if (!debug_pagealloc_enabled())
	22	return;
	23
e30825f1 JK	24	page_poisoning_enabled = true;
	25	}
	26
	27	struct page_ext_operations page_poisoning_ops = {
	28	.need = need_page_poisoning,
	29	.init = init_page_poisoning,
	30	};
	31
6a11f75b AM	32	static inline void set_page_poison(struct page *page)
6a11f75b AM	33	{
e30825f1 JK	34	struct page_ext *page_ext;
	35
	36	page_ext = lookup_page_ext(page);
	37	__set_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
6a11f75b AM	38	}
	39
	40	static inline void clear_page_poison(struct page *page)
	41	{
e30825f1 JK	42	struct page_ext *page_ext;
	43
	44	page_ext = lookup_page_ext(page);
	45	__clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
6a11f75b AM	46	}
	47
	48	static inline bool page_poison(struct page *page)
	49	{
e30825f1 JK	50	struct page_ext *page_ext;
	51
	52	page_ext = lookup_page_ext(page);
	53	return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
6a11f75b AM	54	}
6a11f75b AM	55
6a11f75b AM	56	static void poison_page(struct page *page)
6a11f75b AM	57	{
64212ec5	58	void *addr = kmap_atomic(page);
6a11f75b	59
6a11f75b	60	set_page_poison(page);
6a11f75b	61	memset(addr, PAGE_POISON, PAGE_SIZE);
64212ec5	62	kunmap_atomic(addr);
6a11f75b AM	63	}
	64
	65	static void poison_pages(struct page *page, int n)
	66	{
	67	int i;
	68
	69	for (i = 0; i < n; i++)
	70	poison_page(page + i);
	71	}
	72
	73	static bool single_bit_flip(unsigned char a, unsigned char b)
	74	{
	75	unsigned char error = a ^ b;
	76
	77	return error && !(error & (error - 1));
	78	}
	79
	80	static void check_poison_mem(unsigned char *mem, size_t bytes)
	81	{
77311139	82	static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10);
6a11f75b AM	83	unsigned char *start;
	84	unsigned char *end;
	85
8c5fb8ea AM	86	start = memchr_inv(mem, PAGE_POISON, bytes);
8c5fb8ea AM	87	if (!start)
6a11f75b AM	88	return;
	89
	90	for (end = mem + bytes - 1; end > start; end--) {
	91	if (*end != PAGE_POISON)
	92	break;
	93	}
	94
77311139	95	if (!__ratelimit(&ratelimit))
6a11f75b AM	96	return;
	97	else if (start == end && single_bit_flip(*start, PAGE_POISON))
	98	printk(KERN_ERR "pagealloc: single bit error\n");
	99	else
	100	printk(KERN_ERR "pagealloc: memory corruption\n");
	101
	102	print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start,
	103	end - start + 1, 1);
	104	dump_stack();
	105	}
	106
6a11f75b AM	107	static void unpoison_page(struct page *page)
6a11f75b AM	108	{
64212ec5 AM	109	void *addr;
	110
	111	if (!page_poison(page))
6a11f75b	112	return;
6a11f75b	113
64212ec5 AM	114	addr = kmap_atomic(page);
	115	check_poison_mem(addr, PAGE_SIZE);
	116	clear_page_poison(page);
	117	kunmap_atomic(addr);
6a11f75b AM	118	}
	119
	120	static void unpoison_pages(struct page *page, int n)
	121	{
	122	int i;
	123
	124	for (i = 0; i < n; i++)
	125	unpoison_page(page + i);
	126	}
	127
031bc574	128	void __kernel_map_pages(struct page *page, int numpages, int enable)
6a11f75b	129	{
e30825f1 JK	130	if (!page_poisoning_enabled)
	131	return;
	132
6a11f75b AM	133	if (enable)
	134	unpoison_pages(page, numpages);
	135	else
	136	poison_pages(page, numpages);
	137	}