// SPDX-License-Identifier: GPL-2.0-only

  /*
   * page-types: Tool for querying page flags
   *
   * Copyright (C) 2009 Intel corporation

   *
   * Authors: Wu Fengguang <fengguang.wu@intel.com>

   */

  #define _FILE_OFFSET_BITS 64
  #define _GNU_SOURCE

  #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 <assert.h>

  #include <ftw.h>
  #include <time.h>

  #include <setjmp.h>
  #include <signal.h>

  #include <sys/types.h>
  #include <sys/errno.h>
  #include <sys/fcntl.h>

  #include <sys/mount.h>
  #include <sys/statfs.h>

  #include <sys/mman.h>

  #include "../../include/uapi/linux/magic.h"

  #include "../../include/uapi/linux/kernel-page-flags.h"

  #include <api/fs/fs.h>

  #ifndef MAX_PATH
  # define MAX_PATH 256
  #endif
  
  #ifndef STR
  # define _STR(x) #x
  # define STR(x) _STR(x)
  #endif

  /*

   * pagemap kernel ABI bits
   */

  #define PM_ENTRY_BYTES		8
  #define PM_PFRAME_BITS		55
  #define PM_PFRAME_MASK		((1LL << PM_PFRAME_BITS) - 1)
  #define PM_PFRAME(x)		((x) & PM_PFRAME_MASK)

  #define MAX_SWAPFILES_SHIFT	5
  #define PM_SWAP_OFFSET(x)	(((x) & PM_PFRAME_MASK) >> MAX_SWAPFILES_SHIFT)

  #define PM_SOFT_DIRTY		(1ULL << 55)

  #define PM_MMAP_EXCLUSIVE	(1ULL << 56)

  #define PM_FILE			(1ULL << 61)
  #define PM_SWAP			(1ULL << 62)
  #define PM_PRESENT		(1ULL << 63)

  
  /*

   * kernel page flags
   */
  
  #define KPF_BYTES		8
  #define PROC_KPAGEFLAGS		"/proc/kpageflags"

  #define PROC_KPAGECOUNT		"/proc/kpagecount"

  #define PROC_KPAGECGROUP	"/proc/kpagecgroup"

  #define SYS_KERNEL_MM_PAGE_IDLE "/sys/kernel/mm/page_idle/bitmap"

  /* [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

  #define KPF_SOFTDIRTY		40

  #define KPF_ARCH_2		41

  
  /* [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_FILE		61
  #define KPF_SWAP		62

  #define KPF_MMAP_EXCLUSIVE	63

  
  #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 const char * const 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_HWPOISON]		= "X:hwpoison",

  	[KPF_NOPAGE]		= "n:nopage",

  	[KPF_KSM]		= "x:ksm",

  	[KPF_THP]		= "t:thp",

  	[KPF_OFFLINE]		= "o:offline",

  	[KPF_PGTABLE]		= "g:pgtable",

  	[KPF_ZERO_PAGE]		= "z:zero_page",

  	[KPF_IDLE]              = "i:idle_page",

  
  	[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_SOFTDIRTY]		= "f:softdirty",

  	[KPF_ARCH_2]		= "H:arch_2",

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

  
  	[KPF_FILE]		= "F:file",

  	[KPF_SWAP]		= "w:swap",

  	[KPF_MMAP_EXCLUSIVE]	= "1:mmap_exclusive",

  };
  
  
  /*
   * data structures
   */
  
  static int		opt_raw;	/* for kernel developers */
  static int		opt_list;	/* list pages (in ranges) */

  static int		opt_mark_idle;	/* set accessed bit */

  static int		opt_no_summary;	/* don't show summary */
  static pid_t		opt_pid;	/* process to walk */

  const char		*opt_file;	/* file or directory path */

  static uint64_t		opt_cgroup;	/* cgroup inode */
  static int		opt_list_cgroup;/* list page cgroup */

  static int		opt_list_mapcnt;/* list page map count */

  static const char	*opt_kpageflags;/* kpageflags file to parse */

  
  #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_VMAS	10240
  static int		nr_vmas;
  static unsigned long	pg_start[MAX_VMAS];
  static unsigned long	pg_end[MAX_VMAS];

  #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;

  static int		pagemap_fd;

  static int		kpageflags_fd;

  static int		kpagecount_fd = -1;

  static int		kpagecgroup_fd = -1;

  static int		page_idle_fd = -1;

  static int		opt_hwpoison;
  static int		opt_unpoison;

  static const char	*hwpoison_debug_fs;

  static int		hwpoison_inject_fd;
  static int		hwpoison_forget_fd;

  #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; })

  #define max_t(type, x, y) ({			\
  	type __max1 = (x);			\
  	type __max2 = (y);			\
  	__max1 > __max2 ? __max1 : __max2; })

  static unsigned long pages2mb(unsigned long pages)

  {
  	return (pages * page_size) >> 20;
  }

  static void fatal(const char *x, ...)

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

  static int checked_open(const char *pathname, int flags)

  {
  	int fd = open(pathname, flags);
  
  	if (fd < 0) {
  		perror(pathname);
  		exit(EXIT_FAILURE);
  	}
  
  	return fd;
  }

  /*
   * pagemap/kpageflags routines
   */

  static unsigned long do_u64_read(int fd, const char *name,

  				 uint64_t *buf,
  				 unsigned long index,
  				 unsigned long count)
  {
  	long bytes;
  
  	if (index > ULONG_MAX / 8)
  		fatal("index overflow: %lu
  ", index);

  	bytes = pread(fd, buf, count * 8, (off_t)index * 8);

  	if (bytes < 0) {
  		perror(name);
  		exit(EXIT_FAILURE);
  	}
  	if (bytes % 8)
  		fatal("partial read: %lu bytes
  ", bytes);
  
  	return bytes / 8;
  }
  
  static unsigned long kpageflags_read(uint64_t *buf,
  				     unsigned long index,
  				     unsigned long pages)
  {

  	return do_u64_read(kpageflags_fd, opt_kpageflags, buf, index, pages);

  }

  static unsigned long kpagecgroup_read(uint64_t *buf,
  				      unsigned long index,
  				      unsigned long pages)
  {
  	if (kpagecgroup_fd < 0)
  		return pages;

  	return do_u64_read(kpagecgroup_fd, opt_kpageflags, buf, index, pages);

  }

  static unsigned long kpagecount_read(uint64_t *buf,
  				     unsigned long index,
  				     unsigned long pages)
  {
  	return kpagecount_fd < 0 ? pages :
  		do_u64_read(kpagecount_fd, PROC_KPAGECOUNT,
  			    buf, index, pages);
  }

  static unsigned long pagemap_read(uint64_t *buf,
  				  unsigned long index,
  				  unsigned long pages)
  {
  	return do_u64_read(pagemap_fd, "/proc/pid/pagemap", buf, index, pages);
  }
  
  static unsigned long pagemap_pfn(uint64_t val)
  {
  	unsigned long pfn;
  
  	if (val & PM_PRESENT)
  		pfn = PM_PFRAME(val);
  	else
  		pfn = 0;
  
  	return pfn;
  }

  static unsigned long pagemap_swap_offset(uint64_t val)
  {
  	return val & PM_SWAP ? PM_SWAP_OFFSET(val) : 0;
  }

  
  /*
   * page flag names
   */

  static char *page_flag_name(uint64_t flags)

  {
  	static char buf[65];
  	int present;

  	size_t 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("unknown flag bit %d
  ", i);

  			continue;
  		}
  		buf[j++] = present ? page_flag_names[i][0] : '_';
  	}
  
  	return buf;
  }

  static char *page_flag_longname(uint64_t flags)

  {
  	static char buf[1024];

  	size_t 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
   */

  static void show_page_range(unsigned long voffset, unsigned long offset,

  			    unsigned long size, uint64_t flags,
  			    uint64_t cgroup, uint64_t mapcnt)

  {
  	static uint64_t      flags0;

  	static uint64_t	     cgroup0;

  	static uint64_t      mapcnt0;

  	static unsigned long voff;

  	static unsigned long index;
  	static unsigned long count;

  	if (flags == flags0 && cgroup == cgroup0 && mapcnt == mapcnt0 &&
  	    offset == index + count && size && voffset == voff + count) {

  		count += size;

  		return;
  	}

  	if (count) {
  		if (opt_pid)
  			printf("%lx\t", voff);

  		if (opt_file)
  			printf("%lu\t", voff);

  		if (opt_list_cgroup)
  			printf("@%llu\t", (unsigned long long)cgroup0);

  		if (opt_list_mapcnt)
  			printf("%lu\t", mapcnt0);

  		printf("%lx\t%lx\t%s
  ",

  				index, count, page_flag_name(flags0));

  	}

  
  	flags0 = flags;

  	cgroup0 = cgroup;
  	mapcnt0 = mapcnt;

  	index  = offset;

  	voff   = voffset;

  	count  = size;
  }
  
  static void flush_page_range(void)
  {

  	show_page_range(0, 0, 0, 0, 0, 0);

  }

  static void show_page(unsigned long voffset, unsigned long offset,

  		      uint64_t flags, uint64_t cgroup, uint64_t mapcnt)

  {

  	if (opt_pid)
  		printf("%lx\t", voffset);

  	if (opt_file)
  		printf("%lu\t", voffset);

  	if (opt_list_cgroup)
  		printf("@%llu\t", (unsigned long long)cgroup);

  	if (opt_list_mapcnt)
  		printf("%lu\t", mapcnt);

  	printf("%lx\t%s
  ", offset, page_flag_name(flags));

  }

  static void show_summary(void)

  {

  	size_t i;

  
  	printf("             flags\tpage-count       MB"
  		"  symbolic-flags\t\t\tlong-symbolic-flags
  ");
  
  	for (i = 0; i < ARRAY_SIZE(nr_pages); i++) {
  		if (nr_pages[i])
  			printf("0x%016llx\t%10lu %8lu  %s\t%s
  ",
  				(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
  ",
  			total_pages, pages2mb(total_pages));
  }
  
  
  /*
   * page flag filters
   */

  static 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;
  }

  static uint64_t expand_overloaded_flags(uint64_t flags, uint64_t pme)

  {
  	/* 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);

  	if (pme & PM_SOFT_DIRTY)
  		flags |= BIT(SOFTDIRTY);

  	if (pme & PM_FILE)
  		flags |= BIT(FILE);

  	if (pme & PM_SWAP)
  		flags |= BIT(SWAP);

  	if (pme & PM_MMAP_EXCLUSIVE)
  		flags |= BIT(MMAP_EXCLUSIVE);

  	return flags;
  }

  static 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;
  }

  static uint64_t kpageflags_flags(uint64_t flags, uint64_t pme)

  {

  	if (opt_raw)
  		flags = expand_overloaded_flags(flags, pme);
  	else

  		flags = well_known_flags(flags);
  
  	return flags;
  }

  /*

   * page actions
   */
  
  static void prepare_hwpoison_fd(void)
  {

  	char buf[MAX_PATH + 1];

  	hwpoison_debug_fs = debugfs__mount();

  	if (!hwpoison_debug_fs) {
  		perror("mount debugfs");
  		exit(EXIT_FAILURE);
  	}

  
  	if (opt_hwpoison && !hwpoison_inject_fd) {

  		snprintf(buf, MAX_PATH, "%s/hwpoison/corrupt-pfn",
  			hwpoison_debug_fs);

  		hwpoison_inject_fd = checked_open(buf, O_WRONLY);
  	}
  
  	if (opt_unpoison && !hwpoison_forget_fd) {

  		snprintf(buf, MAX_PATH, "%s/hwpoison/unpoison-pfn",
  			hwpoison_debug_fs);

  		hwpoison_forget_fd = checked_open(buf, O_WRONLY);
  	}
  }
  
  static int hwpoison_page(unsigned long offset)
  {
  	char buf[100];
  	int len;
  
  	len = sprintf(buf, "0x%lx
  ", offset);
  	len = write(hwpoison_inject_fd, buf, len);
  	if (len < 0) {
  		perror("hwpoison inject");
  		return len;
  	}
  	return 0;
  }
  
  static int unpoison_page(unsigned long offset)
  {
  	char buf[100];
  	int len;
  
  	len = sprintf(buf, "0x%lx
  ", offset);
  	len = write(hwpoison_forget_fd, buf, len);
  	if (len < 0) {
  		perror("hwpoison forget");
  		return len;
  	}
  	return 0;
  }

  static int mark_page_idle(unsigned long offset)
  {
  	static unsigned long off;
  	static uint64_t buf;
  	int len;
  
  	if ((offset / 64 == off / 64) || buf == 0) {
  		buf |= 1UL << (offset % 64);
  		off = offset;
  		return 0;
  	}
  
  	len = pwrite(page_idle_fd, &buf, 8, 8 * (off / 64));
  	if (len < 0) {
  		perror("mark page idle");
  		return len;
  	}
  
  	buf = 1UL << (offset % 64);
  	off = offset;
  
  	return 0;
  }

  /*

   * page frame walker
   */

  static size_t hash_slot(uint64_t flags)

  {

  	size_t k = HASH_KEY(flags);
  	size_t 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?
  ");
  	exit(EXIT_FAILURE);
  }

  static void add_page(unsigned long voffset, unsigned long offset,

  		     uint64_t flags, uint64_t cgroup, uint64_t mapcnt,
  		     uint64_t pme)

  {

  	flags = kpageflags_flags(flags, pme);

  
  	if (!bit_mask_ok(flags))
  		return;

  	if (opt_cgroup && cgroup != (uint64_t)opt_cgroup)
  		return;

  	if (opt_hwpoison)
  		hwpoison_page(offset);
  	if (opt_unpoison)
  		unpoison_page(offset);

  	if (opt_mark_idle)
  		mark_page_idle(offset);

  	if (opt_list == 1)

  		show_page_range(voffset, offset, 1, flags, cgroup, mapcnt);

  	else if (opt_list == 2)

  		show_page(voffset, offset, flags, cgroup, mapcnt);

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

  #define KPAGEFLAGS_BATCH	(64 << 10)	/* 64k pages */

  static void walk_pfn(unsigned long voffset,
  		     unsigned long index,

  		     unsigned long count,
  		     uint64_t pme)

  {

  	uint64_t buf[KPAGEFLAGS_BATCH];

  	uint64_t cgi[KPAGEFLAGS_BATCH];

  	uint64_t cnt[KPAGEFLAGS_BATCH];

  	unsigned long batch;

  	unsigned long pages;

  	unsigned long i;

  	/*
  	 * kpagecgroup_read() reads only if kpagecgroup were opened, but
  	 * /proc/kpagecgroup might even not exist, so it's better to fill
  	 * them with zeros here.
  	 */
  	if (count == 1)
  		cgi[0] = 0;
  	else
  		memset(cgi, 0, sizeof cgi);

  	while (count) {

  		batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH);
  		pages = kpageflags_read(buf, index, batch);
  		if (pages == 0)

  			break;

  		if (kpagecgroup_read(cgi, index, pages) != pages)
  			fatal("kpagecgroup returned fewer pages than expected");

  		if (kpagecount_read(cnt, index, pages) != pages)

  			fatal("kpagecount returned fewer pages than expected");

  		for (i = 0; i < pages; i++)

  			add_page(voffset + i, index + i,
  				 buf[i], cgi[i], cnt[i], pme);

  		index += pages;
  		count -= pages;

  	}
  }

  static void walk_swap(unsigned long voffset, uint64_t pme)
  {
  	uint64_t flags = kpageflags_flags(0, pme);
  
  	if (!bit_mask_ok(flags))
  		return;

  	if (opt_cgroup)
  		return;

  	if (opt_list == 1)

  		show_page_range(voffset, pagemap_swap_offset(pme),
  				1, flags, 0, 0);

  	else if (opt_list == 2)

  		show_page(voffset, pagemap_swap_offset(pme), flags, 0, 0);

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

  #define PAGEMAP_BATCH	(64 << 10)
  static void walk_vma(unsigned long index, unsigned long count)

  {

  	uint64_t buf[PAGEMAP_BATCH];
  	unsigned long batch;
  	unsigned long pages;
  	unsigned long pfn;
  	unsigned long i;

  	while (count) {
  		batch = min_t(unsigned long, count, PAGEMAP_BATCH);
  		pages = pagemap_read(buf, index, batch);
  		if (pages == 0)
  			break;

  		for (i = 0; i < pages; i++) {
  			pfn = pagemap_pfn(buf[i]);

  			if (pfn)

  				walk_pfn(index + i, pfn, 1, buf[i]);

  			if (buf[i] & PM_SWAP)
  				walk_swap(index + i, buf[i]);

  		}
  
  		index += pages;
  		count -= pages;
  	}

  }
  
  static void walk_task(unsigned long index, unsigned long count)
  {

  	const unsigned long end = index + count;

  	unsigned long start;
  	int i = 0;

  
  	while (index < end) {
  
  		while (pg_end[i] <= index)
  			if (++i >= nr_vmas)
  				return;
  		if (pg_start[i] >= end)
  			return;

  		start = max_t(unsigned long, pg_start[i], index);
  		index = min_t(unsigned long, pg_end[i], end);

  		assert(start < index);
  		walk_vma(start, index - start);

  	}
  }
  
  static void add_addr_range(unsigned long offset, unsigned long size)
  {
  	if (nr_addr_ranges >= MAX_ADDR_RANGES)
  		fatal("too many addr ranges
  ");
  
  	opt_offset[nr_addr_ranges] = offset;
  	opt_size[nr_addr_ranges] = min_t(unsigned long, size, ULONG_MAX-offset);
  	nr_addr_ranges++;
  }

  static void walk_addr_ranges(void)

  {
  	int i;

  	kpageflags_fd = checked_open(opt_kpageflags, O_RDONLY);

  
  	if (!nr_addr_ranges)

  		add_addr_range(0, ULONG_MAX);

  
  	for (i = 0; i < nr_addr_ranges; i++)

  		if (!opt_pid)

  			walk_pfn(opt_offset[i], opt_offset[i], opt_size[i], 0);

  		else
  			walk_task(opt_offset[i], opt_size[i]);

  	if (opt_mark_idle)
  		mark_page_idle(0);

  	close(kpageflags_fd);
  }
  
  
  /*
   * user interface
   */

  static const char *page_flag_type(uint64_t flag)

  {
  	if (flag & KPF_HACKERS_BITS)
  		return "(r)";
  	if (flag & KPF_OVERLOADED_BITS)
  		return "(o)";
  	return "   ";
  }

  static void usage(void)

  {

  	size_t i, j;

  
  	printf(
  "page-types [options]
  "

  "            -r|--raw                   Raw mode, for kernel developers
  "

  "            -d|--describe flags        Describe flags
  "

  "            -a|--addr    addr-spec     Walk a range of pages
  "
  "            -b|--bits    bits-spec     Walk pages with specified bits
  "

  "            -c|--cgroup  path|@inode   Walk pages within memory cgroup
  "

  "            -p|--pid     pid           Walk process address space
  "

  "            -f|--file    filename      Walk file address space
  "

  "            -i|--mark-idle             Mark pages idle
  "

  "            -l|--list                  Show page details in ranges
  "
  "            -L|--list-each             Show page details one by one
  "

  "            -C|--list-cgroup           Show cgroup inode for pages
  "

  "            -M|--list-mapcnt           Show page map count
  "

  "            -N|--no-summary            Don't show summary info
  "

  "            -X|--hwpoison              hwpoison pages
  "
  "            -x|--unpoison              unpoison pages
  "

  "            -F|--kpageflags filename   kpageflags file to parse
  "

  "            -h|--help                  Show this usage message
  "

  "flags:
  "

  "            0x10                       bitfield format, e.g.
  "
  "            anon                       bit-name, e.g.
  "
  "            0x10,anon                  comma-separated list, e.g.
  "

  "addr-spec:
  "

  "            N                          one page at offset N (unit: pages)
  "
  "            N+M                        pages range from N to N+M-1
  "
  "            N,M                        pages range from N to M-1
  "
  "            N,                         pages range from N to end
  "
  "            ,M                         pages range from 0 to M-1
  "

  "bits-spec:
  "

  "            bit1,bit2                  (flags & (bit1|bit2)) != 0
  "
  "            bit1,bit2=bit1             (flags & (bit1|bit2)) == bit1
  "
  "            bit1,~bit2                 (flags & (bit1|bit2)) == bit1
  "
  "            =bit1,bit2                 flags == (bit1|bit2)
  "

  "bit-names:
  "
  	);
  
  	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('
  ');
  		}
  	}
  	printf("
                                     "
  		"(r) raw mode bits  (o) overloaded bits
  ");
  }

  static 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
  ", str);
  
  	return n;
  }

  static void parse_pid(const char *str)

  {

  	FILE *file;
  	char buf[5000];

  	opt_pid = parse_number(str);

  	sprintf(buf, "/proc/%d/pagemap", opt_pid);

  	pagemap_fd = checked_open(buf, O_RDONLY);

  
  	sprintf(buf, "/proc/%d/maps", opt_pid);
  	file = fopen(buf, "r");
  	if (!file) {
  		perror(buf);
  		exit(EXIT_FAILURE);
  	}
  
  	while (fgets(buf, sizeof(buf), file) != NULL) {
  		unsigned long vm_start;
  		unsigned long vm_end;
  		unsigned long long pgoff;
  		int major, minor;
  		char r, w, x, s;
  		unsigned long ino;
  		int n;
  
  		n = sscanf(buf, "%lx-%lx %c%c%c%c %llx %x:%x %lu",
  			   &vm_start,
  			   &vm_end,
  			   &r, &w, &x, &s,
  			   &pgoff,
  			   &major, &minor,
  			   &ino);
  		if (n < 10) {
  			fprintf(stderr, "unexpected line: %s
  ", buf);
  			continue;
  		}
  		pg_start[nr_vmas] = vm_start / page_size;
  		pg_end[nr_vmas] = vm_end / page_size;
  		if (++nr_vmas >= MAX_VMAS) {
  			fprintf(stderr, "too many VMAs
  ");
  			break;
  		}
  	}
  	fclose(file);

  }

  static void show_file(const char *name, const struct stat *st)
  {
  	unsigned long long size = st->st_size;
  	char atime[64], mtime[64];
  	long now = time(NULL);
  
  	printf("%s\tInode: %u\tSize: %llu (%llu pages)
  ",
  			name, (unsigned)st->st_ino,
  			size, (size + page_size - 1) / page_size);
  
  	strftime(atime, sizeof(atime), "%c", localtime(&st->st_atime));
  	strftime(mtime, sizeof(mtime), "%c", localtime(&st->st_mtime));
  
  	printf("Modify: %s (%ld seconds ago)
  Access: %s (%ld seconds ago)
  ",
  			mtime, now - st->st_mtime,
  			atime, now - st->st_atime);
  }

  static sigjmp_buf sigbus_jmp;
  
  static void * volatile sigbus_addr;
  
  static void sigbus_handler(int sig, siginfo_t *info, void *ucontex)
  {
  	(void)sig;
  	(void)ucontex;
  	sigbus_addr = info ? info->si_addr : NULL;
  	siglongjmp(sigbus_jmp, 1);
  }
  
  static struct sigaction sigbus_action = {
  	.sa_sigaction = sigbus_handler,
  	.sa_flags = SA_SIGINFO,
  };

  static void walk_file(const char *name, const struct stat *st)
  {
  	uint8_t vec[PAGEMAP_BATCH];
  	uint64_t buf[PAGEMAP_BATCH], flags;

  	uint64_t cgroup = 0;

  	uint64_t mapcnt = 0;

  	unsigned long nr_pages, pfn, i;

  	off_t off, end = st->st_size;

  	int fd;

  	ssize_t len;
  	void *ptr;
  	int first = 1;
  
  	fd = checked_open(name, O_RDONLY|O_NOATIME|O_NOFOLLOW);

  	for (off = 0; off < end; off += len) {
  		nr_pages = (end - off + page_size - 1) / page_size;

  		if (nr_pages > PAGEMAP_BATCH)
  			nr_pages = PAGEMAP_BATCH;
  		len = nr_pages * page_size;
  
  		ptr = mmap(NULL, len, PROT_READ, MAP_SHARED, fd, off);
  		if (ptr == MAP_FAILED)
  			fatal("mmap failed: %s", name);
  
  		/* determine cached pages */
  		if (mincore(ptr, len, vec))
  			fatal("mincore failed: %s", name);
  
  		/* turn off readahead */
  		if (madvise(ptr, len, MADV_RANDOM))
  			fatal("madvice failed: %s", name);

  		if (sigsetjmp(sigbus_jmp, 1)) {
  			end = off + sigbus_addr ? sigbus_addr - ptr : 0;
  			fprintf(stderr, "got sigbus at offset %lld: %s
  ",
  					(long long)end, name);
  			goto got_sigbus;
  		}

  		/* populate ptes */
  		for (i = 0; i < nr_pages ; i++) {
  			if (vec[i] & 1)
  				(void)*(volatile int *)(ptr + i * page_size);
  		}

  got_sigbus:

  
  		/* turn off harvesting reference bits */
  		if (madvise(ptr, len, MADV_SEQUENTIAL))
  			fatal("madvice failed: %s", name);
  
  		if (pagemap_read(buf, (unsigned long)ptr / page_size,
  					nr_pages) != nr_pages)
  			fatal("cannot read pagemap");
  
  		munmap(ptr, len);
  
  		for (i = 0; i < nr_pages; i++) {
  			pfn = pagemap_pfn(buf[i]);
  			if (!pfn)
  				continue;
  			if (!kpageflags_read(&flags, pfn, 1))
  				continue;

  			if (!kpagecgroup_read(&cgroup, pfn, 1))
  				fatal("kpagecgroup_read failed");

  			if (!kpagecount_read(&mapcnt, pfn, 1))
  				fatal("kpagecount_read failed");

  			if (first && opt_list) {
  				first = 0;
  				flush_page_range();
  				show_file(name, st);
  			}

  			add_page(off / page_size + i, pfn,

  				 flags, cgroup, mapcnt, buf[i]);

  		}
  	}
  
  	close(fd);
  }
  
  int walk_tree(const char *name, const struct stat *st, int type, struct FTW *f)
  {
  	(void)f;
  	switch (type) {
  	case FTW_F:
  		if (S_ISREG(st->st_mode))
  			walk_file(name, st);
  		break;
  	case FTW_DNR:
  		fprintf(stderr, "cannot read dir: %s
  ", name);
  		break;
  	}
  	return 0;
  }
  
  static void walk_page_cache(void)
  {
  	struct stat st;

  	kpageflags_fd = checked_open(opt_kpageflags, O_RDONLY);

  	pagemap_fd = checked_open("/proc/self/pagemap", O_RDONLY);

  	sigaction(SIGBUS, &sigbus_action, NULL);

  
  	if (stat(opt_file, &st))
  		fatal("stat failed: %s
  ", opt_file);
  
  	if (S_ISREG(st.st_mode)) {
  		walk_file(opt_file, &st);
  	} else if (S_ISDIR(st.st_mode)) {
  		/* do not follow symlinks and mountpoints */
  		if (nftw(opt_file, walk_tree, 64, FTW_MOUNT | FTW_PHYS) < 0)
  			fatal("nftw failed: %s
  ", opt_file);
  	} else
  		fatal("unhandled file type: %s
  ", opt_file);
  
  	close(kpageflags_fd);
  	close(pagemap_fd);

  	signal(SIGBUS, SIG_DFL);

  }

  static void parse_file(const char *name)

  {

  	opt_file = name;

  }

  static void parse_cgroup(const char *path)
  {
  	if (path[0] == '@') {
  		opt_cgroup = parse_number(path + 1);
  		return;
  	}
  
  	struct stat st;
  
  	if (stat(path, &st))
  		fatal("stat failed: %s: %m
  ", path);
  
  	if (!S_ISDIR(st.st_mode))
  		fatal("cgroup supposed to be a directory: %s
  ", path);
  
  	opt_cgroup = st.st_ino;
  }

  static 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
  ",
  							offset, size);
  				size -= offset;
  			}
  		}
  	} else {
  		offset = parse_number(optarg);
  		size   = 1;
  	}
  
  	add_addr_range(offset, size);
  }

  static void add_bits_filter(uint64_t mask, uint64_t bits)

  {
  	if (nr_bit_filters >= MAX_BIT_FILTERS)
  		fatal("too much bit filters
  ");
  
  	opt_mask[nr_bit_filters] = mask;
  	opt_bits[nr_bit_filters] = bits;
  	nr_bit_filters++;
  }

  static uint64_t parse_flag_name(const char *str, int len)

  {

  	size_t 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);
  }

  static 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;
  }

  static 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);
  }

  static void parse_kpageflags(const char *name)
  {
  	opt_kpageflags = name;
  }

  static void describe_flags(const char *optarg)
  {
  	uint64_t flags = parse_flag_names(optarg, 0);
  
  	printf("0x%016llx\t%s\t%s
  ",
  		(unsigned long long)flags,
  		page_flag_name(flags),
  		page_flag_longname(flags));
  }

  static const struct option opts[] = {

  	{ "raw"       , 0, NULL, 'r' },
  	{ "pid"       , 1, NULL, 'p' },
  	{ "file"      , 1, NULL, 'f' },
  	{ "addr"      , 1, NULL, 'a' },
  	{ "bits"      , 1, NULL, 'b' },

  	{ "cgroup"    , 1, NULL, 'c' },

  	{ "describe"  , 1, NULL, 'd' },

  	{ "mark-idle" , 0, NULL, 'i' },

  	{ "list"      , 0, NULL, 'l' },
  	{ "list-each" , 0, NULL, 'L' },

  	{ "list-cgroup", 0, NULL, 'C' },

  	{ "list-mapcnt", 0, NULL, 'M' },

  	{ "no-summary", 0, NULL, 'N' },

  	{ "hwpoison"  , 0, NULL, 'X' },
  	{ "unpoison"  , 0, NULL, 'x' },

  	{ "kpageflags", 0, NULL, 'F' },

  	{ "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:d:c:CilLMNXxF:h",

  				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 'c':
  			parse_cgroup(optarg);
  			break;
  		case 'C':
  			opt_list_cgroup = 1;
  			break;

  		case 'd':

  			describe_flags(optarg);

  			exit(0);

  		case 'i':
  			opt_mark_idle = 1;
  			break;

  		case 'l':
  			opt_list = 1;
  			break;
  		case 'L':
  			opt_list = 2;
  			break;

  		case 'M':
  			opt_list_mapcnt = 1;
  			break;

  		case 'N':
  			opt_no_summary = 1;
  			break;

  		case 'X':
  			opt_hwpoison = 1;
  			prepare_hwpoison_fd();
  			break;
  		case 'x':
  			opt_unpoison = 1;
  			prepare_hwpoison_fd();
  			break;

  		case 'F':
  			parse_kpageflags(optarg);
  			break;

  		case 'h':
  			usage();
  			exit(0);
  		default:
  			usage();
  			exit(1);
  		}
  	}

  	if (!opt_kpageflags)
  		opt_kpageflags = PROC_KPAGEFLAGS;

  	if (opt_cgroup || opt_list_cgroup)
  		kpagecgroup_fd = checked_open(PROC_KPAGECGROUP, O_RDONLY);

  	if (opt_list && opt_list_mapcnt)
  		kpagecount_fd = checked_open(PROC_KPAGECOUNT, O_RDONLY);

  	if (opt_mark_idle && opt_file)
  		page_idle_fd = checked_open(SYS_KERNEL_MM_PAGE_IDLE, O_RDWR);

  	if (opt_list && opt_pid)
  		printf("voffset\t");

  	if (opt_list && opt_file)
  		printf("foffset\t");

  	if (opt_list && opt_list_cgroup)
  		printf("cgroup\t");

  	if (opt_list && opt_list_mapcnt)
  		printf("map-cnt\t");

  	if (opt_list == 1)

  		printf("offset\tlen\tflags
  ");

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

  	if (opt_file)
  		walk_page_cache();
  	else
  		walk_addr_ranges();

  
  	if (opt_list == 1)

  		flush_page_range();

  
  	if (opt_no_summary)
  		return 0;
  
  	if (opt_list)
  		printf("
  
  ");
  
  	show_summary();

  	if (opt_list_mapcnt)
  		close(kpagecount_fd);

  	if (page_idle_fd >= 0)
  		close(page_idle_fd);

  	return 0;
  }