[media] V4L1 API has been moved into "legacy" on the linuxtv.org site

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / Documentation / vm / page-types.c

/*
 * page-types: Tool for querying page flags
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; version 2.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should find a copy of v2 of the GNU General Public License somewhere on
 * your Linux system; if not, write to the Free Software Foundation, Inc., 59
 * Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * Copyright (C) 2009 Intel corporation
 *
 * Authors: Wu Fengguang <fengguang.wu@intel.com>
 */

#define _LARGEFILE64_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 <sys/types.h>
#include <sys/errno.h>
#include <sys/fcntl.h>
#include <sys/mount.h>
#include <sys/statfs.h>
#include "../../include/linux/magic.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      sizeof(uint64_t)
#define PM_STATUS_BITS      3
#define PM_STATUS_OFFSET    (64 - PM_STATUS_BITS)
#define PM_STATUS_MASK      (((1LL << PM_STATUS_BITS) - 1) << PM_STATUS_OFFSET)
#define PM_STATUS(nr)       (((nr) << PM_STATUS_OFFSET) & PM_STATUS_MASK)
#define PM_PSHIFT_BITS      6
#define PM_PSHIFT_OFFSET    (PM_STATUS_OFFSET - PM_PSHIFT_BITS)
#define PM_PSHIFT_MASK      (((1LL << PM_PSHIFT_BITS) - 1) << PM_PSHIFT_OFFSET)
#define PM_PSHIFT(x)        (((u64) (x) << PM_PSHIFT_OFFSET) & PM_PSHIFT_MASK)
#define PM_PFRAME_MASK      ((1LL << PM_PSHIFT_OFFSET) - 1)
#define PM_PFRAME(x)        ((x) & PM_PFRAME_MASK)

#define PM_PRESENT          PM_STATUS(4LL)
#define PM_SWAP             PM_STATUS(2LL)


/*
 * 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_HWPOISON            19
#define KPF_NOPAGE              20
#define KPF_KSM                 21

/* [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 const 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_HWPOISON]          = "X:hwpoison",
        [KPF_NOPAGE]            = "n:nopage",
        [KPF_KSM]               = "x:ksm",

        [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",
};


static const char *debugfs_known_mountpoints[] = {
        "/sys/kernel/debug",
        "/debug",
        0,
};

/*
 * 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_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              opt_hwpoison;
static int              opt_unpoison;

static char             hwpoison_debug_fs[MAX_PATH+1];
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, char *name,
                                 uint64_t *buf,
                                 unsigned long index,
                                 unsigned long count)
{
        long bytes;

        if (index > ULONG_MAX / 8)
                fatal("index overflow: %lu\n", index);

        if (lseek(fd, index * 8, SEEK_SET) < 0) {
                perror(name);
                exit(EXIT_FAILURE);
        }

        bytes = read(fd, buf, count * 8);
        if (bytes < 0) {
                perror(name);
                exit(EXIT_FAILURE);
        }
        if (bytes % 8)
                fatal("partial read: %lu bytes\n", bytes);

        return bytes / 8;
}

static unsigned long kpageflags_read(uint64_t *buf,
                                     unsigned long index,
                                     unsigned long pages)
{
        return do_u64_read(kpageflags_fd, PROC_KPAGEFLAGS, 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;
}


/*
 * page flag names
 */

static 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("unknown flag bit %d\n", i);
                        continue;
                }
                buf[j++] = present ? page_flag_names[i][0] : '_';
        }

        return buf;
}

static 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
 */

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

        if (flags == flags0 && offset == index + count &&
            (!opt_pid || voffset == voff + count)) {
                count++;
                return;
        }

        if (count) {
                if (opt_pid)
                        printf("%lx\t", voff);
                printf("%lx\t%lx\t%s\n",
                                index, count, page_flag_name(flags0));
        }

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

static void show_page(unsigned long voffset,
                      unsigned long offset, uint64_t flags)
{
        if (opt_pid)
                printf("%lx\t", voffset);
        printf("%lx\t%s\n", offset, page_flag_name(flags));
}

static 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
 */

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)
{
        /* 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;
}

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)
{
        flags = expand_overloaded_flags(flags);

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

        return flags;
}

/* verify that a mountpoint is actually a debugfs instance */
static int debugfs_valid_mountpoint(const char *debugfs)
{
        struct statfs st_fs;

        if (statfs(debugfs, &st_fs) < 0)
                return -ENOENT;
        else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
                return -ENOENT;

        return 0;
}

/* find the path to the mounted debugfs */
static const char *debugfs_find_mountpoint(void)
{
        const char **ptr;
        char type[100];
        FILE *fp;

        ptr = debugfs_known_mountpoints;
        while (*ptr) {
                if (debugfs_valid_mountpoint(*ptr) == 0) {
                        strcpy(hwpoison_debug_fs, *ptr);
                        return hwpoison_debug_fs;
                }
                ptr++;
        }

        /* give up and parse /proc/mounts */
        fp = fopen("/proc/mounts", "r");
        if (fp == NULL)
                perror("Can't open /proc/mounts for read");

        while (fscanf(fp, "%*s %"
                      STR(MAX_PATH)
                      "s %99s %*s %*d %*d\n",
                      hwpoison_debug_fs, type) == 2) {
                if (strcmp(type, "debugfs") == 0)
                        break;
        }
        fclose(fp);

        if (strcmp(type, "debugfs") != 0)
                return NULL;

        return hwpoison_debug_fs;
}

/* mount the debugfs somewhere if it's not mounted */

static void debugfs_mount(void)
{
        const char **ptr;

        /* see if it's already mounted */
        if (debugfs_find_mountpoint())
                return;

        ptr = debugfs_known_mountpoints;
        while (*ptr) {
                if (mount(NULL, *ptr, "debugfs", 0, NULL) == 0) {
                        /* save the mountpoint */
                        strcpy(hwpoison_debug_fs, *ptr);
                        break;
                }
                ptr++;
        }

        if (*ptr == NULL) {
                perror("mount debugfs");
                exit(EXIT_FAILURE);
        }
}

/*
 * page actions
 */

static void prepare_hwpoison_fd(void)
{
        char buf[MAX_PATH + 1];

        debugfs_mount();

        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\n", 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\n", offset);
        len = write(hwpoison_forget_fd, buf, len);
        if (len < 0) {
                perror("hwpoison forget");
                return len;
        }
        return 0;
}

/*
 * page frame walker
 */

static 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);
}

static void add_page(unsigned long voffset,
                     unsigned long offset, uint64_t flags)
{
        flags = kpageflags_flags(flags);

        if (!bit_mask_ok(flags))
                return;

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

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

        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 buf[KPAGEFLAGS_BATCH];
        unsigned long batch;
        long pages;
        unsigned long i;

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

                for (i = 0; i < pages; i++)
                        add_page(voffset + i, index + i, buf[i]);

                index += pages;
                count -= 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);
                }

                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\n");

        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(PROC_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(0, opt_offset[i], opt_size[i]);
                else
                        walk_task(opt_offset[i], opt_size[i]);

        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)
{
        int i, j;

        printf(
"page-types [options]\n"
"            -r|--raw                   Raw mode, for kernel developers\n"
"            -d|--describe flags        Describe flags\n"
"            -a|--addr    addr-spec     Walk a range of pages\n"
"            -b|--bits    bits-spec     Walk pages with specified bits\n"
"            -p|--pid     pid           Walk process address space\n"
#if 0 /* planned features */
"            -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 summary info\n"
"            -X|--hwpoison              hwpoison pages\n"
"            -x|--unpoison              unpoison pages\n"
"            -h|--help                  Show this usage message\n"
"flags:\n"
"            0x10                       bitfield format, e.g.\n"
"            anon                       bit-name, e.g.\n"
"            0x10,anon                  comma-separated list, e.g.\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-1\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");
}

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\n", 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\n", 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\n");
                        break;
                }
        }
        fclose(file);
}

static void parse_file(const char *name)
{
}

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\n",
                                                        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\n");

        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)
{
        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);
}

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 describe_flags(const char *optarg)
{
        uint64_t flags = parse_flag_names(optarg, 0);

        printf("0x%016llx\t%s\t%s\n",
                (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' },
        { "describe"  , 1, NULL, 'd' },
        { "list"      , 0, NULL, 'l' },
        { "list-each" , 0, NULL, 'L' },
        { "no-summary", 0, NULL, 'N' },
        { "hwpoison"  , 0, NULL, 'X' },
        { "unpoison"  , 0, NULL, 'x' },
        { "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:lLNXxh", 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 'd':
                        describe_flags(optarg);
                        exit(0);
                case 'l':
                        opt_list = 1;
                        break;
                case 'L':
                        opt_list = 2;
                        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 'h':
                        usage();
                        exit(0);
                default:
                        usage();
                        exit(1);
                }
        }

        if (opt_list && opt_pid)
                printf("voffset\t");
        if (opt_list == 1)
                printf("offset\tlen\tflags\n");
        if (opt_list == 2)
                printf("offset\tflags\n");

        walk_addr_ranges();

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

        if (opt_no_summary)
                return 0;

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

        show_summary();

        return 0;
}