Documentation/vm/page-types.c

/*
 * page-types: Tool for querying page flags
 *
 * Copyright (C) 2009 Intel corporation
 * Copyright (C) 2009 Wu Fengguang <fengguang.wu@intel.com>
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <stdarg.h>
#include <string.h>
#include <getopt.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/errno.h>
#include <sys/fcntl.h>


/*
 * kernel page flags
 */

#define KPF_BYTES		8
#define PROC_KPAGEFLAGS		"/proc/kpageflags"

/* copied from kpageflags_read() */
#define KPF_LOCKED		0
#define KPF_ERROR		1
#define KPF_REFERENCED		2
#define KPF_UPTODATE		3
#define KPF_DIRTY		4
#define KPF_LRU			5
#define KPF_ACTIVE		6
#define KPF_SLAB		7
#define KPF_WRITEBACK		8
#define KPF_RECLAIM		9
#define KPF_BUDDY		10

/* [11-20] new additions in 2.6.31 */
#define KPF_MMAP		11
#define KPF_ANON		12
#define KPF_SWAPCACHE		13
#define KPF_SWAPBACKED		14
#define KPF_COMPOUND_HEAD	15
#define KPF_COMPOUND_TAIL	16
#define KPF_HUGE		17
#define KPF_UNEVICTABLE		18
#define KPF_NOPAGE		20

/* [32-] kernel hacking assistances */
#define KPF_RESERVED		32
#define KPF_MLOCKED		33
#define KPF_MAPPEDTODISK	34
#define KPF_PRIVATE		35
#define KPF_PRIVATE_2		36
#define KPF_OWNER_PRIVATE	37
#define KPF_ARCH		38
#define KPF_UNCACHED		39

/* [48-] take some arbitrary free slots for expanding overloaded flags
 * not part of kernel API
 */
#define KPF_READAHEAD		48
#define KPF_SLOB_FREE		49
#define KPF_SLUB_FROZEN		50
#define KPF_SLUB_DEBUG		51

#define KPF_ALL_BITS		((uint64_t)~0ULL)
#define KPF_HACKERS_BITS	(0xffffULL << 32)
#define KPF_OVERLOADED_BITS	(0xffffULL << 48)
#define BIT(name)		(1ULL << KPF_##name)
#define BITS_COMPOUND		(BIT(COMPOUND_HEAD) | BIT(COMPOUND_TAIL))

static char *page_flag_names[] = {
	[KPF_LOCKED]		= "L:locked",
	[KPF_ERROR]		= "E:error",
	[KPF_REFERENCED]	= "R:referenced",
	[KPF_UPTODATE]		= "U:uptodate",
	[KPF_DIRTY]		= "D:dirty",
	[KPF_LRU]		= "l:lru",
	[KPF_ACTIVE]		= "A:active",
	[KPF_SLAB]		= "S:slab",
	[KPF_WRITEBACK]		= "W:writeback",
	[KPF_RECLAIM]		= "I:reclaim",
	[KPF_BUDDY]		= "B:buddy",

	[KPF_MMAP]		= "M:mmap",
	[KPF_ANON]		= "a:anonymous",
	[KPF_SWAPCACHE]		= "s:swapcache",
	[KPF_SWAPBACKED]	= "b:swapbacked",
	[KPF_COMPOUND_HEAD]	= "H:compound_head",
	[KPF_COMPOUND_TAIL]	= "T:compound_tail",
	[KPF_HUGE]		= "G:huge",
	[KPF_UNEVICTABLE]	= "u:unevictable",
	[KPF_NOPAGE]		= "n:nopage",

	[KPF_RESERVED]		= "r:reserved",
	[KPF_MLOCKED]		= "m:mlocked",
	[KPF_MAPPEDTODISK]	= "d:mappedtodisk",
	[KPF_PRIVATE]		= "P:private",
	[KPF_PRIVATE_2]		= "p:private_2",
	[KPF_OWNER_PRIVATE]	= "O:owner_private",
	[KPF_ARCH]		= "h:arch",
	[KPF_UNCACHED]		= "c:uncached",

	[KPF_READAHEAD]		= "I:readahead",
	[KPF_SLOB_FREE]		= "P:slob_free",
	[KPF_SLUB_FROZEN]	= "A:slub_frozen",
	[KPF_SLUB_DEBUG]	= "E:slub_debug",
};


/*
 * data structures
 */

static int		opt_raw;	/* for kernel developers */
static int		opt_list;	/* list pages (in ranges) */
static int		opt_no_summary;	/* don't show summary */
static pid_t		opt_pid;	/* process to walk */

#define MAX_ADDR_RANGES	1024
static int		nr_addr_ranges;
static unsigned long	opt_offset[MAX_ADDR_RANGES];
static unsigned long	opt_size[MAX_ADDR_RANGES];

#define MAX_BIT_FILTERS	64
static int		nr_bit_filters;
static uint64_t		opt_mask[MAX_BIT_FILTERS];
static uint64_t		opt_bits[MAX_BIT_FILTERS];

static int		page_size;

#define PAGES_BATCH	(64 << 10)	/* 64k pages */
static int		kpageflags_fd;
static uint64_t		kpageflags_buf[KPF_BYTES * PAGES_BATCH];

#define HASH_SHIFT	13
#define HASH_SIZE	(1 << HASH_SHIFT)
#define HASH_MASK	(HASH_SIZE - 1)
#define HASH_KEY(flags)	(flags & HASH_MASK)

static unsigned long	total_pages;
static unsigned long	nr_pages[HASH_SIZE];
static uint64_t 	page_flags[HASH_SIZE];


/*
 * helper functions
 */

#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))

#define min_t(type, x, y) ({			\
	type __min1 = (x);			\
	type __min2 = (y);			\
	__min1 < __min2 ? __min1 : __min2; })

unsigned long pages2mb(unsigned long pages)
{
	return (pages * page_size) >> 20;
}

void fatal(const char *x, ...)
{
	va_list ap;

	va_start(ap, x);
	vfprintf(stderr, x, ap);
	va_end(ap);
	exit(EXIT_FAILURE);
}


/*
 * page flag names
 */

char *page_flag_name(uint64_t flags)
{
	static char buf[65];
	int present;
	int i, j;

	for (i = 0, j = 0; i < ARRAY_SIZE(page_flag_names); i++) {
		present = (flags >> i) & 1;
		if (!page_flag_names[i]) {
			if (present)
				fatal("unkown flag bit %d\n", i);
			continue;
		}
		buf[j++] = present ? page_flag_names[i][0] : '_';
	}

	return buf;
}

char *page_flag_longname(uint64_t flags)
{
	static char buf[1024];
	int i, n;

	for (i = 0, n = 0; i < ARRAY_SIZE(page_flag_names); i++) {
		if (!page_flag_names[i])
			continue;
		if ((flags >> i) & 1)
			n += snprintf(buf + n, sizeof(buf) - n, "%s,",
					page_flag_names[i] + 2);
	}
	if (n)
		n--;
	buf[n] = '\0';

	return buf;
}


/*
 * page list and summary
 */

void show_page_range(unsigned long offset, uint64_t flags)
{
	static uint64_t      flags0;
	static unsigned long index;
	static unsigned long count;

	if (flags == flags0 && offset == index + count) {
		count++;
		return;
	}

	if (count)
		printf("%lu\t%lu\t%s\n",
				index, count, page_flag_name(flags0));

	flags0 = flags;
	index  = offset;
	count  = 1;
}

void show_page(unsigned long offset, uint64_t flags)
{
	printf("%lu\t%s\n", offset, page_flag_name(flags));
}

void show_summary(void)
{
	int i;

	printf("             flags\tpage-count       MB"
		"  symbolic-flags\t\t\tlong-symbolic-flags\n");

	for (i = 0; i < ARRAY_SIZE(nr_pages); i++) {
		if (nr_pages[i])
			printf("0x%016llx\t%10lu %8lu  %s\t%s\n",
				(unsigned long long)page_flags[i],
				nr_pages[i],
				pages2mb(nr_pages[i]),
				page_flag_name(page_flags[i]),
				page_flag_longname(page_flags[i]));
	}

	printf("             total\t%10lu %8lu\n",
			total_pages, pages2mb(total_pages));
}


/*
 * page flag filters
 */

int bit_mask_ok(uint64_t flags)
{
	int i;

	for (i = 0; i < nr_bit_filters; i++) {
		if (opt_bits[i] == KPF_ALL_BITS) {
			if ((flags & opt_mask[i]) == 0)
				return 0;
		} else {
			if ((flags & opt_mask[i]) != opt_bits[i])
				return 0;
		}
	}

	return 1;
}

uint64_t expand_overloaded_flags(uint64_t flags)
{
	/* SLOB/SLUB overload several page flags */
	if (flags & BIT(SLAB)) {
		if (flags & BIT(PRIVATE))
			flags ^= BIT(PRIVATE) | BIT(SLOB_FREE);
		if (flags & BIT(ACTIVE))
			flags ^= BIT(ACTIVE) | BIT(SLUB_FROZEN);
		if (flags & BIT(ERROR))
			flags ^= BIT(ERROR) | BIT(SLUB_DEBUG);
	}

	/* PG_reclaim is overloaded as PG_readahead in the read path */
	if ((flags & (BIT(RECLAIM) | BIT(WRITEBACK))) == BIT(RECLAIM))
		flags ^= BIT(RECLAIM) | BIT(READAHEAD);

	return flags;
}

uint64_t well_known_flags(uint64_t flags)
{
	/* hide flags intended only for kernel hacker */
	flags &= ~KPF_HACKERS_BITS;

	/* hide non-hugeTLB compound pages */
	if ((flags & BITS_COMPOUND) && !(flags & BIT(HUGE)))
		flags &= ~BITS_COMPOUND;

	return flags;
}


/*
 * page frame walker
 */

int hash_slot(uint64_t flags)
{
	int k = HASH_KEY(flags);
	int i;

	/* Explicitly reserve slot 0 for flags 0: the following logic
	 * cannot distinguish an unoccupied slot from slot (flags==0).
	 */
	if (flags == 0)
		return 0;

	/* search through the remaining (HASH_SIZE-1) slots */
	for (i = 1; i < ARRAY_SIZE(page_flags); i++, k++) {
		if (!k || k >= ARRAY_SIZE(page_flags))
			k = 1;
		if (page_flags[k] == 0) {
			page_flags[k] = flags;
			return k;
		}
		if (page_flags[k] == flags)
			return k;
	}

	fatal("hash table full: bump up HASH_SHIFT?\n");
	exit(EXIT_FAILURE);
}

void add_page(unsigned long offset, uint64_t flags)
{
	flags = expand_overloaded_flags(flags);

	if (!opt_raw)
		flags = well_known_flags(flags);

	if (!bit_mask_ok(flags))
		return;

	if (opt_list == 1)
		show_page_range(offset, flags);
	else if (opt_list == 2)
		show_page(offset, flags);

	nr_pages[hash_slot(flags)]++;
	total_pages++;
}

void walk_pfn(unsigned long index, unsigned long count)
{
	unsigned long batch;
	unsigned long n;
	unsigned long i;

	if (index > ULONG_MAX / KPF_BYTES)
		fatal("index overflow: %lu\n", index);

	lseek(kpageflags_fd, index * KPF_BYTES, SEEK_SET);

	while (count) {
		batch = min_t(unsigned long, count, PAGES_BATCH);
		n = read(kpageflags_fd, kpageflags_buf, batch * KPF_BYTES);
		if (n == 0)
			break;
		if (n < 0) {
			perror(PROC_KPAGEFLAGS);
			exit(EXIT_FAILURE);
		}

		if (n % KPF_BYTES != 0)
			fatal("partial read: %lu bytes\n", n);
		n = n / KPF_BYTES;

		for (i = 0; i < n; i++)
			add_page(index + i, kpageflags_buf[i]);

		index += batch;
		count -= batch;
	}
}

void walk_addr_ranges(void)
{
	int i;

	kpageflags_fd = open(PROC_KPAGEFLAGS, O_RDONLY);
	if (kpageflags_fd < 0) {
		perror(PROC_KPAGEFLAGS);
		exit(EXIT_FAILURE);
	}

	if (!nr_addr_ranges)
		walk_pfn(0, ULONG_MAX);

	for (i = 0; i < nr_addr_ranges; i++)
		walk_pfn(opt_offset[i], opt_size[i]);

	close(kpageflags_fd);
}


/*
 * user interface
 */

const char *page_flag_type(uint64_t flag)
{
	if (flag & KPF_HACKERS_BITS)
		return "(r)";
	if (flag & KPF_OVERLOADED_BITS)
		return "(o)";
	return "   ";
}

void usage(void)
{
	int i, j;

	printf(
"page-types [options]\n"
"            -r|--raw                  Raw mode, for kernel developers\n"
"            -a|--addr    addr-spec    Walk a range of pages\n"
"            -b|--bits    bits-spec    Walk pages with specified bits\n"
#if 0 /* planned features */
"            -p|--pid     pid          Walk process address space\n"
"            -f|--file    filename     Walk file address space\n"
#endif
"            -l|--list                 Show page details in ranges\n"
"            -L|--list-each            Show page details one by one\n"
"            -N|--no-summary           Don't show summay info\n"
"            -h|--help                 Show this usage message\n"
"addr-spec:\n"
"            N                         one page at offset N (unit: pages)\n"
"            N+M                       pages range from N to N+M-1\n"
"            N,M                       pages range from N to M-1\n"
"            N,                        pages range from N to end\n"
"            ,M                        pages range from 0 to M\n"
"bits-spec:\n"
"            bit1,bit2                 (flags & (bit1|bit2)) != 0\n"
"            bit1,bit2=bit1            (flags & (bit1|bit2)) == bit1\n"
"            bit1,~bit2                (flags & (bit1|bit2)) == bit1\n"
"            =bit1,bit2                flags == (bit1|bit2)\n"
"bit-names:\n"
	);

	for (i = 0, j = 0; i < ARRAY_SIZE(page_flag_names); i++) {
		if (!page_flag_names[i])
			continue;
		printf("%16s%s", page_flag_names[i] + 2,
				 page_flag_type(1ULL << i));
		if (++j > 3) {
			j = 0;
			putchar('\n');
		}
	}
	printf("\n                                   "
		"(r) raw mode bits  (o) overloaded bits\n");
}

unsigned long long parse_number(const char *str)
{
	unsigned long long n;

	n = strtoll(str, NULL, 0);

	if (n == 0 && str[0] != '0')
		fatal("invalid name or number: %s\n", str);

	return n;
}

void parse_pid(const char *str)
{
	opt_pid = parse_number(str);
}

void parse_file(const char *name)
{
}

void add_addr_range(unsigned long offset, unsigned long size)
{
	if (nr_addr_ranges >= MAX_ADDR_RANGES)
		fatal("too much addr ranges\n");

	opt_offset[nr_addr_ranges] = offset;
	opt_size[nr_addr_ranges] = size;
	nr_addr_ranges++;
}

void parse_addr_range(const char *optarg)
{
	unsigned long offset;
	unsigned long size;
	char *p;

	p = strchr(optarg, ',');
	if (!p)
		p = strchr(optarg, '+');

	if (p == optarg) {
		offset = 0;
		size   = parse_number(p + 1);
	} else if (p) {
		offset = parse_number(optarg);
		if (p[1] == '\0')
			size = ULONG_MAX;
		else {
			size = parse_number(p + 1);
			if (*p == ',') {
				if (size < offset)
					fatal("invalid range: %lu,%lu\n",
							offset, size);
				size -= offset;
			}
		}
	} else {
		offset = parse_number(optarg);
		size   = 1;
	}

	add_addr_range(offset, size);
}

void add_bits_filter(uint64_t mask, uint64_t bits)
{
	if (nr_bit_filters >= MAX_BIT_FILTERS)
		fatal("too much bit filters\n");

	opt_mask[nr_bit_filters] = mask;
	opt_bits[nr_bit_filters] = bits;
	nr_bit_filters++;
}

uint64_t parse_flag_name(const char *str, int len)
{
	int i;

	if (!*str || !len)
		return 0;

	if (len <= 8 && !strncmp(str, "compound", len))
		return BITS_COMPOUND;

	for (i = 0; i < ARRAY_SIZE(page_flag_names); i++) {
		if (!page_flag_names[i])
			continue;
		if (!strncmp(str, page_flag_names[i] + 2, len))
			return 1ULL << i;
	}

	return parse_number(str);
}

uint64_t parse_flag_names(const char *str, int all)
{
	const char *p    = str;
	uint64_t   flags = 0;

	while (1) {
		if (*p == ',' || *p == '=' || *p == '\0') {
			if ((*str != '~') || (*str == '~' && all && *++str))
				flags |= parse_flag_name(str, p - str);
			if (*p != ',')
				break;
			str = p + 1;
		}
		p++;
	}

	return flags;
}

void parse_bits_mask(const char *optarg)
{
	uint64_t mask;
	uint64_t bits;
	const char *p;

	p = strchr(optarg, '=');
	if (p == optarg) {
		mask = KPF_ALL_BITS;
		bits = parse_flag_names(p + 1, 0);
	} else if (p) {
		mask = parse_flag_names(optarg, 0);
		bits = parse_flag_names(p + 1, 0);
	} else if (strchr(optarg, '~')) {
		mask = parse_flag_names(optarg, 1);
		bits = parse_flag_names(optarg, 0);
	} else {
		mask = parse_flag_names(optarg, 0);
		bits = KPF_ALL_BITS;
	}

	add_bits_filter(mask, bits);
}


struct option opts[] = {
	{ "raw"       , 0, NULL, 'r' },
	{ "pid"       , 1, NULL, 'p' },
	{ "file"      , 1, NULL, 'f' },
	{ "addr"      , 1, NULL, 'a' },
	{ "bits"      , 1, NULL, 'b' },
	{ "list"      , 0, NULL, 'l' },
	{ "list-each" , 0, NULL, 'L' },
	{ "no-summary", 0, NULL, 'N' },
	{ "help"      , 0, NULL, 'h' },
	{ NULL        , 0, NULL, 0 }
};

int main(int argc, char *argv[])
{
	int c;

	page_size = getpagesize();

	while ((c = getopt_long(argc, argv,
				"rp:f:a:b:lLNh", opts, NULL)) != -1) {
		switch (c) {
		case 'r':
			opt_raw = 1;
			break;
		case 'p':
			parse_pid(optarg);
			break;
		case 'f':
			parse_file(optarg);
			break;
		case 'a':
			parse_addr_range(optarg);
			break;
		case 'b':
			parse_bits_mask(optarg);
			break;
		case 'l':
			opt_list = 1;
			break;
		case 'L':
			opt_list = 2;
			break;
		case 'N':
			opt_no_summary = 1;
			break;
		case 'h':
			usage();
			exit(0);
		default:
			usage();
			exit(1);
		}
	}

	if (opt_list == 1)
		printf("offset\tcount\tflags\n");
	if (opt_list == 2)
		printf("offset\tflags\n");

	walk_addr_ranges();

	if (opt_list == 1)
		show_page_range(0, 0);  /* drain the buffer */

	if (opt_no_summary)
		return 0;

	if (opt_list)
		printf("\n\n");

	show_summary();

	return 0;
}